BACKGROUND
[0001] The present invention, in some embodiments thereof, relates to an alarm system and,
more specifically, but not exclusively, to detecting an attempt at unauthorized disarming
of an alarm system.
[0002] A typical alarm system installed on premises comprises one or more sensors for detecting
motion, presence or intrusion, protecting one or more openings in premises or one
or more areas of the premises. The protected areas may be indoors or outdoors. A gate,
a door and a window are examples of possible openings protected by a sensor. The one
or more sensors are typically connected to a control panel, which may be in communication
with a control center. Upon detection of motion on premises, presence of a person
or object on premises or an attempt at intruding the premises, for example by detecting
opening of a protected opening, at least one of the sensors sends a signal to the
control panel which may transmit a signal to the control center. After processing
the signal, the control center may take one or more actions, for example calling an
emergency center or activating an audio or visual alarm signal.
[0003] Alarm systems are installed in a wide variety of homes, offices, businesses and other
locations. A typical alarm system may be in one of a plurality of possible states,
including fully disabled, fully active, and partially active. For example, an alarm
system may be fully disabled at an office during office business hours. When the alarm
system is fully disabled, the one or more sensors may not detect movement, presence
or intrusion into premises, or the control panel may not transmit a signal to the
control center. An alarm may be fully active at the office after office business hours,
when the office may be empty. When the alarm system is fully active, all of the one
or more sensors may be active to detect movement, presence or intrusion into premises.
At a house, an alarm system may be partially active at night, where some of the one
or more sensors are active and some are disabled. For example, in a possible partially
active state some sensors protecting exterior openings of the house such as windows
and doors may be enabled, whereas other sensors for detecting motion in rooms of the
house may be disabled, to allow persons living in the house to move freely in the
house. Alternatively, the control panel may receive all sensor indications but may
transmit to the control center only the relevant indications.
[0004] In some alarm systems, the plurality of states are controlled using one or more radio
frequency (RF) signals. In such systems, the control panel typically includes a signal
processor to receive one or more RF signals from a control device, for example a key
fob having a plurality of buttons for controlling the state of the alarm system. In
such systems, a person may press one of the plurality of buttons of the key fob to
instruct the alarm system to change state to a requested state, resulting in the key
fob sending an RF signal indicative of the requested state to the signal processor.
Upon reception of the signal, the signal processor processes the signal, identifies
the requested state and instructs changing the state of the alarm system to the requested
state.
SUMMARY
[0005] It is an object of the present invention to provide a system and method for detecting
an attempt at unauthorized disarming of an alarm system.
[0006] The foregoing and other objects are achieved by the features of the independent claims.
Further implementation forms are apparent from the dependent claims, the description
and the figures.
[0007] Aspects and embodiments of the present invention are set out in the appended claims.
These and other aspects and embodiments of the invention are also described herein.
[0008] According to a first aspect of the invention, an alarm system, comprises at least
one radio-frequency (RF) transceiver and at least one signal processor, electrically
connected to the at least one RF transceiver. The at least one RF transceiver is configured
to: receive a first disarm RF signal from an alarm control device; and during a predetermined
delay time after receiving the first disarm RF signal, transmit at least one deception
RF signal during one or more transmission time slots selected from a plurality of
consecutive time slots of the predetermined delay time, and determine whether one
or more receive RF signals are received during one or more receiving time slots selected
from the plurality of consecutive time slots, the one or more receiving time slots
interleaved with the one or more transmission time slots. The at least one signal
processor is configured to determine an alarm system operation according to analysis
of the one or more receive RF signals.
[0009] According to a second aspect of the invention, a method for an alarm system, comprises:
receiving a first disarm RF signal from an alarm control device; during a predetermined
delay time after receiving the first disarm RF signal, transmitting at least one deception
RF signal during one or more transmission time slots selected from a plurality of
consecutive time slots of the predetermined delay time, and determining whether one
or more receive RF signals are received during one or more receiving time slots selected
from the plurality of consecutive time slots, the one or more receiving time slots
interleaved with the one or more transmission time slots; and determining an alarm
system operation according to analysis of the one or more receive RF signals.
[0010] With reference to the first and second aspects, in a first possible implementation
of the first and second aspects of the present invention the analysis comprises: matching
at least one of the one or more receive RF signals with a predefined deception signal
pattern; producing a true deception detection indication for each one of the one or
more receive RF signals matching the predefined deception signal pattern; and selecting
the alarm system operation according to the true deception detection indication. Detecting
one deception signal is sufficient to identify an attempted intrusion.
[0011] With reference to the first and second aspects, in a second possible implementation
of the first and second aspects of the present invention the analysis comprises: producing
a false deception detection indication subject to none of the one or more receive
RF signals being received during the one or more receiving time slots or each one
of the one or more receive RF signals failing to match the predefined deception signal
pattern; and selecting the alarm system operation according to the false deception
detection indication. When no RF signals are detected during the receiving slots,
or when none of the one or more received RF signals match the predefined deception
signal pattern, no deception is detected.
[0012] With reference to the first and second aspects, or to the first and second implementations
of the first and second aspects, in a third possible implementation of the first and
second aspects of the present invention the at least one signal processor is further
configured to: determine the first disarm RF signal is valid, subject to not receiving
any of the one or more receive RF signals or producing only false deception detection
indications; and receive a second disarm RF signal from the alarm control device after
the predetermined delay time. Upon receiving the second disarm RF signal, the alarm
system operation comprises at least one of: instructing disarming the alarm system,
and transmitting an acknowledgement RF signal to the alarm control device via the
at least one RF transceiver. After identifying a valid disarm signal, also the retry
may be considered valid.
[0013] With reference to the first and second aspects, in a fourth possible implementation
of the first and second aspects of the present invention the transmission time slots
are selected at random by the signal processor upon reception of the first disarm
RF signal for transmitting the at least one deception RF signal, and the reception
time slots comprise all of the plurality of consecutive time slots different from
the transmission time slots. Selecting a random pattern of transmitting slots reduces
the probability of repeating the same sequence and increases the probability of detecting
a recorded deception signal in one of the receiving slots. Listening for received
signals during all remaining time slots increases probability of detecting a retransmitted
deception sequence.
[0014] With reference to the first and second aspects, in a fifth possible implementation
of the first and second aspects of the present invention an amount of the transmission
time slots is between 15
% and 30
% of an amount of the plurality of consecutive time slots. This ratio allows a balance
between high probability of detecting a deception and reducing overhead of frequently
changing between transmission and reception.
[0015] With reference to the first and second aspects, in a sixth possible implementation
of the first and second aspects of the present invention the predetermined delay time
is partitioned into 25 consecutive time slots. This amount of consecutive time slots
allows a balance between high probability of detecting a deception and reducing overhead
of frequently changing between transmission and reception.
[0016] With reference to the first and second aspects, in a seventh possible implementation
of the first and second aspects of the present invention the at least one deception
RF signal is protected by an error detecting code being a 16-bit cyclic redundancy
check. Protecting the at least one deception RF signal reduces the probability of
falsely detecting deception. 16-bit cyclic redundancy check is easy to implement and
introduces little overhead to processing and bandwidth.
[0017] With reference to the first and second aspects, in an eighth possible implementation
of the first and second aspects of the present invention the at least one deception
RF signal is encrypted using a method selected from the group of: obfuscation, exclusive-or
with a predefined seed word, and exclusive-or with a random seed word. Encrypting
the at least one deception RF signal reduces the probability of an unauthorized party
distinguishing between the at least one deception RF signal and the disarm RF signal.
Obfuscation and exclusive-or are easy to implement and introduce little overhead to
processing and bandwidth.
[0018] With reference to the first and second aspects, in a ninth possible implementation
of the first and second aspects of the present invention alarm system operation comprises
at least one operation selected from the group comprising: notifying a control center
operatively connected to said at least one signal processor of an attempted intrusion,
subject to producing at least one true deception detection indication and delivering
an electrical current to a device capable of emitting an audio signal or a visual
signal, electrically connected to said at least one signal processor, subject to producing
at least one true deception detection indication.
[0019] With reference to the first and second aspects, or to the first implementation of
the first and second aspects, in a tenth possible implementation of the first and
second aspects of the present invention the at least one deception RF signal comprises
at least one of: an identifier, a time stamp and a random number, for use in identifying
an origin of a recorded deception RF signal. Optionally, the identifier consists of
32 binary bits, the time stamp consists of 32 binary bits, and the random number consists
of 8 binary bits. Optionally, matching the predefined deception signal pattern comprises
detecting in the one received RF signal at least one of: an identifier, a time stamp
and a random number.
[0020] With reference to the first and second aspects, or to the first implementation of
the first and second aspects, in an eleventh possible implementation of the first
and second aspects of the present invention the analysis further comprises: detecting
a packet number in the first disarm RF signal; comparing a difference between the
packet number and a previously stored packet number with a predefined threshold number;
and producing a true deception detection indication when the difference is greater
than the predefined threshold number. Adding a packet number to the disarm RF signal
provides an additional means for detecting resending a recorded signal by detecting
a repeated packet number.
[0021] Other systems, methods, features, and advantages of the present disclosure will be
or become apparent to one with skill in the art upon examination of the following
drawings and detailed description. It is intended that all such additional systems,
methods, features, and advantages be included within this description, be within the
scope of the present disclosure, and be protected by the accompanying claims.
[0022] Unless otherwise defined, all technical and/or scientific terms used herein have
the same meaning as commonly understood by one of ordinary skill in the art to which
the invention pertains. Although methods and materials similar or equivalent to those
described herein can be used in the practice or testing of embodiments of the invention,
exemplary methods and/or materials are described below. In case of conflict, the patent
specification, including definitions, will control. In addition, the materials, methods,
and examples are illustrative only and are not intended to be necessarily limiting.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0023] Some embodiments of the invention are herein described, by way of example only, with
reference to the accompanying drawings. With specific reference now to the drawings
in detail, it is stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of embodiments of the invention. In this regard,
the description taken with the drawings makes apparent to those skilled in the art
how embodiments of the invention may be practiced.
[0024] In the drawings:
FIG. 1 is a schematic illustration of an exemplary system according to some embodiments
of the present invention;
FIGs. 2A, 2B, 2C, and 2D are schematic illustrations of exemplary RF signals with
respect to time, according to some embodiments of the present invention;
FIG. 3 is a flowchart schematically representing an optional flow of operations for
detecting an intrusion attempt using interleaved transmission and reception of a deception
signal, according to some embodiments of the present invention;
FIG. 4 is a flowchart schematically representing an optional flow of operations for
detecting an intrusion attempt using RF signal imperfections of a signal, according
to some embodiments of the present invention;
FIG. 5 is a flowchart schematically representing another optional flow of operations
for detecting an intrusion attempt using RF signal imperfections of a signal, according
to some embodiments of the present invention;
FIG. 6 is a flowchart schematically representing an optional flow of operations for
producing reference signal imperfections, according to some embodiments of the present
invention; and
FIGs. 7A and 7B are time sequences schematically representing an optional flow of
operations for detecting an intrusion attempt using an invalid instruction, according
to some embodiments of the present invention.
DETAILED DESCRIPTION
[0025] The present invention, in some embodiments thereof, relates to an alarm system and,
more specifically, but not exclusively, to detecting an attempt at unauthorized disarming
of an alarm system.
[0026] As used herein, the term "disarm" means "instructing to change to a disabled or a
partially active state" and the term "signal" means "RF signal".
[0027] Attempts to intrude into a premises protected by an alarm system may include attempts
to break through any component of the alarm system.
[0028] A typical RF signal may be detected and recorded in an identified range of distances
from a device sending the RF signal. In an alarm system controlled using one or more
radio frequency (RF) signals, a person unauthorized to access the premises may record
a legitimate signal sent by an alarm control device instructing to disarm the alarm
system, and retransmit the recorded signal at a later time. A typical alarm system
cannot distinguish between the original legitimate signal and the recorded signal,
and upon reception of the recorded signal the alarm system's signal processer may
instruct disarming the alarm system. Thus, a recorded signal may be used to gain unauthorized
access to premises.
[0029] Authentication solutions using encrypted signals or including predefined information
in one or more signals transmitted by an alarm control device are limited in that
they require replacing multiple existing alarm control devices, for example replacing
existing key fobs with alarm control devices supporting encryption or predefined information.
In addition, alarm control devices supporting encryption or sending predefined information
may be more expensive than existing simple alarm control devices such as existing
key fobs.
[0030] The present invention, in some embodiments thereof, enables an alarm system to distinguish
between a legitimate signal and retransmission of a previously recorded signal, without
requiring a specially configured alarm control device, by changing the way the signal
processor operates.
[0031] In some embodiments of the present invention, the signal processor, after receiving
a disarm signal from an alarm control device, sends one or more deception signals.
An attempt to record the disarm signal will record the one or more deception signals
as well. When transmitting the recorded signal, the one or more deception signals
are transmitted as well and may be received by the signal processor. In these embodiments,
the signal processor interchangeably transmits the one or more deception signals and
checks for reception of one or more other signals. When one or more of the other signals
are determined to be deception signals, the signal processor determines an attempt
at unauthorized intrusion.
[0032] In other embodiments of the present invention, the signal processor analyzes the
RF signal imperfections of a received disarm signal for imperfections. A typical signal
transmitted by an alarm control device comprises a sequence of digital bits encoded
in an analog carrier signal comprising a plurality of sinus signal components. When
an RF transceiver encodes digital bits in an analog carrier signal and transmits the
resulting RF signal, the transceiver introduces noise into the transmitted signal,
including at least one of a frequency imperfection of a sinus signal, a phase imperfection
of a sinus signal and an amplitude imperfection of a sinus signal. For example: carrier
frequency offset, phase noise, in-phase and quadrature (IQ) imbalance and signal nonlinearity
(that is, nonlinear changes in an output signal strength in response to an input signal
strength). Such noise, referred to as RF signal imperfections, is signal imperfection
of the RF transceiver and may be quantified, combined and normalized, resulting for
example in a number between 0 and 1. Two RF transceivers are typically characterized
by distinctively different RF signal imperfections. A recorded disarm signal typically
comprises a recorded sequence of digital bits. When an unauthorized alarm control
device transmits a recorded disarm signal, the unauthorized alarm control device re-encodes
the recorded sequence of digital bits in a new analog carrier signal. The RF signal
imperfections of the signal transmitted by the unauthorized alarm control device will
be different from the RF signal imperfections of the original disarm signal, resulting
in the RF imperfections of the signal transmitted by the unauthorized alarm control
device being different from the RF imperfections of the original disarm signal. In
these embodiments, the signal processor compares the RF imperfections of a received
preamble signal to a predetermined set of RF imperfections associated with legitimate
transmitters. When the RF imperfections of the received preamble signal do not comply
with the predetermined set of RF imperfections, the signal processor determines in
these embodiments an attempt at unauthorized intrusion.
[0033] In other embodiments of the present invention, the alarm control device is configured
to send a signal indicating an event, and receive a signal including an identification
of a function to be executed by the alarm control device. For example the alarm control
device may be a key fob, configured to send a signal indicating a button pressed and
a duration, for example "short press on button 1", and receive a signal including
an encoding of an identification of a function, for example "function 3". A possible
function is to turn on a light emitting diode (LED) for a predetermined period of
time. Optionally, upon receiving a signal including an encoding of an identification
of a function unrecognized by the alarm control device, the alarm control device sends
an error message indicating an error and the identification of the unrecognized function.
In these embodiments, the signal processor, after receiving a disarm signal from an
alarm control device, sends a deception signal including a randomly selected identifier
of an invalid function. An attempt to record the disarm signal will record the deception
signal as well. When transmitting the recorded signal, the deception signal is transmitted
as well and may be received by the signal processor. In these embodiments, after transmitting
a deception signal including an invalid-function identifier, the signal processor
checks for reception of another signal. When another signal is received, the received
signal is processed to extract a possible unknown-function identifier. When an unknown-function
identifier is extracted, the extracted identifier is compared with the invalid-function
identifier. When the extracted identifier is other than the invalid-function identifier,
the signal processor determines in these embodiments an attempt at unauthorized intrusion,
since the extracted identifier is assumed to be the result of a pre-recorded signal.
[0034] Before explaining at least one embodiment of the invention in detail, it is to be
understood that the invention is not necessarily limited in its application to the
details of construction and the arrangement of the components and/or methods set forth
in the following description and/or illustrated in the drawings and/or the Examples.
The invention is capable of other embodiments or of being practiced or carried out
in various ways.
[0035] The present invention may be a system, a method, and/or a computer program product.
The computer program product may include a computer readable storage medium (or media)
having computer readable program instructions thereon for causing a processor to carry
out aspects of the present invention.
[0036] The computer readable storage medium can be a tangible device that can retain and
store instructions for use by an instruction execution device. The computer readable
storage medium may be, for example, but is not limited to, an electronic storage device,
a magnetic storage device, an optical storage device, an electromagnetic storage device,
a semiconductor storage device, or any suitable combination of the foregoing.
[0037] Computer readable program instructions described herein can be downloaded to respective
computing/processing devices from a computer readable storage medium or to an external
computer or external storage device via a network, for example, the Internet, a local
area network, a wide area network and/or a wireless network.
[0038] The computer readable program instructions may execute entirely on the user's computer,
partly on the user's computer, as a stand-alone software package, partly on the user's
computer and partly on a remote computer or entirely on the remote computer or server.
In the latter scenario, the remote computer may be connected to the user's computer
through any type of network, including a local area network (LAN) or a wide area network
(WAN), or the connection may be made to an external computer (for example, through
the Internet using an Internet Service Provider). In some embodiments, electronic
circuitry including, for example, programmable logic circuitry, field-programmable
gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable
program instructions by utilizing state information of the computer readable program
instructions to personalize the electronic circuitry, in order to perform aspects
of the present invention.
[0039] Aspects of the present invention are described herein with reference to flowchart
illustrations and/or block diagrams of methods, apparatus (systems), and computer
program products according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block diagrams, and combinations
of blocks in the flowchart illustrations and/or block diagrams, can be implemented
by computer readable program instructions.
[0040] The flowchart and block diagrams in the Figures illustrate the architecture, functionality,
and operation of possible implementations of systems, methods, and computer program
products according to various embodiments of the present invention. In this regard,
each block in the flowchart or block diagrams may represent a module, segment, or
portion of instructions, which comprises one or more executable instructions for implementing
the specified logical function(s). In some alternative implementations, the functions
noted in the block may occur out of the order noted in the figures. For example, two
blocks shown in succession may, in fact, be executed substantially concurrently, or
the blocks may sometimes be executed in the reverse order, depending upon the functionality
involved. It will also be noted that each block of the block diagrams and/or flowchart
illustration, and combinations of blocks in the block diagrams and/or flowchart illustration,
can be implemented by special purpose hardware-based systems that perform the specified
functions or acts or carry out combinations of special purpose hardware and computer
instructions.
[0041] Reference is now made to FIG. 1, showing a schematic illustration of an exemplary
system 100 according to some embodiments of the present invention. In such embodiments,
system 100 comprises one or more sensors 111, for detecting motion within premises,
presence within the premises or intrusion into an opening of the premises. One or
more sensors 110 may be connected to a control panel 106 comprising alarm controller
110 comprising at least one hardware processor. Optionally, alarm controller 110 is
configured to instruct activation of the one or more sensors and disabling the one
or more sensors.
[0042] In addition, in such embodiments system 100 comprises a signal processor 101 connected
to alarm controller 110 for controlling the system. Signal processor 101 may be electrically
connected to alarm controller 110. Optionally, signal processor 101 is connected to
alarm controller 110 via a digital communication network, such as a Local Area Network.
Optionally, signal processor 101 is electrically connected to alarm controller 110.
[0043] Optionally, signal processor 101 is electrically connected to an RF transceiver 102,
for communicating with one or more alarm control devices 103 such as key fobs. Optionally,
signal processor 101 comprises at least one hardware processor. In such embodiments
RF transceiver 102 receives one or more RF signals from alarm control device 103.
Optionally, each of the one or more RF signals encodes a sequence of digital bits
in an analog carrier signal. Optionally, one or more of the RF signals is a disarm
message, sent from alarm control device 103 to signal processor 101 to instruct disarming
alarm system 100. Optionally, signal processor 101 processes the disarm message to
determine whether the message is a valid message received from an authorized alarm
control device, or an unauthorized intrusion attempt. Upon determining a valid disarm
message, signal processor 101 may instruct disarming alarm system 100. Optionally,
signal processor 101 instructs alarm controller 110 to disarm the system.
[0044] In some embodiments, signal processor 101 is electrically connected to one or more
alarm devices 105 capable of emitting an audio signal such as an alarm sound, and/or
a visual signal such as a flashing light, to attract the attention of a person close
enough to one or more alarm devices 105 to notice the alarm signal or visual signal.
Optionally, upon detecting an intrusion attempt, signal processor 101 drives an electrical
current to one or more alarm devices 105 to emit the audio or visual signal. In some
embodiments, signal processor 101 is connected to one or more control centers 104,
comprising at least one hardware processor. Optionally, upon detecting an intrusion
attempt, signal processor 101 notifies control center 104 of the intrusion attempt
detection. Following receiving notification of an intrusion attempt detection, control
center 104may perform one or more actions such as call a designated person, record
an event to an event log, etc.
[0045] In some embodiments, signal processor 101 is electrically connected to a non-volatile
digital storage 112 such as a hard disk or an electrically erasable programmable memory,
for the purpose of storing reference data used to determine validity of a received
message.
[0046] To determine whether a received message is valid, system 100 may implement one or
more of the following methods.
[0047] A possible method to detect an intrusion attempt uses interleaved transmission and
reception of a deception signal.
[0048] Reference is now made also to FIG. 2A, showing a schematic illustration of an exemplary
RF disarm signal transmitted by an alarm control device 103 to a signal processor
101, according to some embodiments of the present invention. Following time line 210,
at time 211 alarm control device 103 transmits in such embodiments a first disarm
message 201. Optionally, time 212 indicates the time at which alarm control device
103 completed transmission of disarm message 201. Optionally, after a predetermined
delay time after time 212, if alarm control device 103 does not receive an acknowledgement
signal from signal processor 101 alarm control device 103 transmits a second disarm
message 202 at time 214.
[0049] Upon receiving a disarm message, in some embodiments of the present invention signal
processor 101 transmits a deception signal. Reference is now made also to FIG. 2B,
showing a schematic illustration of a possible deception RF signal transmitted by
a signal processor 101 via an RF transceiver 102, according to some embodiments of
the present invention. In such embodiments, the predetermined delay time is partitioned
into a plurality of consecutive time slots. A non-limiting example of an amount of
time slots is 25 time slots. Optionally, time 213 indicates the earliest time at which
RF transceiver 102 receiving disarm message 201 can start transmitting. Optionally,
signal processor 101 selects a group of transmission time slots from the plurality
of consecutive time slots and transmits one or more deception sequences 220 by transmitting
in each of the transmission time slots one deception sequence. A recorder recording
the signals transmitted to signal processor 101 will record both disarm message 201
and the one or more deception sequences 220. Reference in now made also to FIG. 2C,
showing a schematic illustration of a possible recorded RF signal, according to some
embodiments of the present invention. In such embodiments, the recorded signal 230
comprises disarm message 201, and the one or more deception sequences 220 transmitted
by signal processor 101.
[0050] Optionally, the group of transmission slots is selected at random by signal processor
101 upon receiving a disarm message, and comprises fewer slots than the plurality
of consecutive time slots. For example, the amount of transmission slots is between
15
% and 30
% of the amount of slots in the plurality of consecutive time slots. For example, the
amount of transmission slots is 25
% of the amount of slots in the plurality of consecutive time slots. For example, when
the predetermined delay time is partitioned into 25 time slots, the amount of transmission
time slots may be 5.
[0051] In some embodiments, an unauthorized alarm control device transmitting a recorded
signal transmits the disarm message originally transmitted by an authorized alarm
control device, followed by the one or more disarm sequences as previously transmitted
by the signal processor.
[0052] Reference is now made also to FIG. 2D, showing a schematic illustration of a possible
retransmitted recorded RF signal, compared to a new deception signal, according to
some embodiments of the present invention. In such embodiments, an alarm control device
105 transmits at time 241 a recorded signal 250, comprising a disarm signal 201 originally
transmitted by an authorized alarm control device. Optionally, transmission of disarm
signal 201 ends at time 242. Upon reception of disarm message 201, signal processor
101 selects a new group of transmit slots from the plurality of consecutive time slots
between time 243 and time 244, and transmits via RF transceiver 102 one or more deception
signals 260. The new group of transmit slots may be different from the group of transmit
slots in the recorded signal. Optionally, RF transceiver 102 listens for received
signals in a group of receive time slots selected from the plurality of consecutive
time slots such that the receive time slots are different from the new group of transmit
time slots and are interleaved with the new group of transmit time slots. In some
embodiments the receive time slots are all of the plurality of consecutive time slots
not in the new transmit time slots. When transmit time slots are selected at random,
there is a probability greater than zero that the new group of transmit time slots
is different from the group of time slots in the recorded signal. Depending on the
number of time slots and the number of transmit time slots, the probability can exceed
0.99. As a result, signal processor 101 optionally detects one or more recorded deception
sequences during the receive time slots, for example in slot 262. Optionally, one
or more time slots are both in the new group of transmit time slots and in the group
of transmit time slots in the recorded signal, for example slot 261. In such slots,
signal processor 101 cannot detect a deception signal, since transceiver 102 is transmitting.
[0053] Detecting a deception signal in a receive time slot indicates a high probability
that the disarm signal is a recorded signal retransmitted by an unauthorized alarm
control device. Depending on the amount of time slots in the plurality of consecutive
time slots and the amount of transmit time slots, detecting no deception signal in
any of the receive time slots indicates a high probability that the disarm signal
was transmitted by an authorized alarm control device. For example, when the plurality
of consecutive time slots comprises 25 time slots and the group of transmit time slots
comprises 5 time slots, the probability of repeating the exact same group of time
slots is less than 1 in 50,000. Using fewer time slots in the plurality of consecutive
time slots increases the probability of repeating an exact same group of time slots.
A greater amount of time slots in the plurality of consecutive time slots or a greater
amount of transmit slots may increase security by reducing the probability of repeating
an exact same group of time slots, but in addition might increase power consumption
due to more frequently switching the RF transceiver between transmitting and receiving.
[0054] Following is an optional method implemented by system 100 in some embodiments of
the present invention, to detect an intrusion attempt using interleaved transmission
and reception of a deception signal.
[0055] Reference is now made also to FIG. 3, showing a flowchart schematically representing
an optional flow of operations 300 for detecting an intrusion attempt using interleaved
transmission and reception of a deception signal, according to some embodiments of
the present invention.
[0056] In such embodiments, an RF transceiver 102 electrically connected to a signal processor
101 receives at 301 a first disarm RF signal from an alarm control device 103. Optionally,
after transmitting the first disarm RF message, alarm control device 103 waits for
an acknowledgement from signal processor 101 for a predetermined delay time. Optionally,
signal processor 101 partitions the predetermined delay time into a plurality of consecutive
time slots, for example 25 time slots. During the predetermined delay time, optionally
signal processor 101 transmits at 302 one or more deception RF signals during transmission
time slots selected from the plurality of consecutive time slots. Optionally, each
of the one or more deception RF signals comprises at least one of an identifier, a
time stamp and a random number. An identifier may be used to identify the origin of
a deception RF signal, and in particular a recorded RF signal. A time stamp may be
used to identify an original time of a recorded deception RF signal. A random number
may be used to detect repeated deception RF signals, having the same random number.
A time stamp and an identifier may each consist of 32 digital bits. A random number
may consist of 8 digital bits. Optionally, each of the one or more deception RF signals
comprises a packet number in a sequence of packet numbers. The packet number may consist
of an 8 bit digital number. When the packet number consists of 8 digital bits, the
packet number is a number in a sequence modulo 256.
[0057] In addition, during the predetermined delay time, signal processor 101 optionally
intercepts at 303 a plurality of RF signals during receiving time slots selected from
the plurality of consecutive time slots and interleaved with the transmission time
slots. When one or more receive RF signals are detected in the receive time slots,
RF transceiver 102 optionally sends the one or more RF signals to signal processor
101. Optionally, signal processor 101 receives the one or more RF signals and analyzes
the first disarm RF signal and the one or more RF signals to produce at least one
deception detection indication. In some embodiments, analyzing the one or more RF
signals comprises matching at 304 at least one of the one or more RF signals with
a predefined deception signal pattern. In embodiments where the one or more deception
sequences comprise at least one of an identifier, a time stamp and a random number,
matching one of the RF signals with the predefined deception signal pattern comprises
detecting in the one RF signal at least one of an identifier, a time stamp and a random
number. When one of the RF signals matches the predefined deception signal pattern,
signal processor 101 produces at 305 a true deception detection indication. In embodiments
where the first disarm RF message comprises a packet number, signal processor 101
may store a last packet number received. In such embodiments, analyzing the first
disarm RF message comprises detecting a packet number in the first disarm RF message
and comparing a difference between the stored packet number and the detected packet
number with a predefined threshold number. When the difference is greater than the
predefined threshold number, signal processor 101 optionally produces a true deception
detection indication.
[0058] At 314, signal processor 101 optionally determines an alarm system operation according
to the at least one deception detection indication. Examples of an alarm system operation
are processing a message, sending an acknowledgement signal, instructing disarming
the alarm system, sounding an alarm and notifying a control center. When at least
one true deception detection indication is produced, signal processor 101 optionally
determines an intrusion attempt at 308. Optionally, signal processor 101 next notifies
control center 104 at 309. Optionally, at 310 signal processor 101 delivers an electrical
current to one or more alarm devices 105 capable of emitting an audio signal or a
visual signal.
[0059] When no true deception detection indication is produced, signal processor 101 optionally
determines a valid first disarm RF signal. Optionally, signal processor 101 determines
a valid first disarm RF signal when no RF signals are received in the receive time
slots. In some embodiments, after the predefined delay time alarm control device 103
sends a second disarm RF signal. Optionally, signal processor 101 receives the second
disarm signal via RF transceiver 102 at 311 after determining a valid first disarm
RF signal, and at 312 optionally sends alarm control device 103 an acknowledgment
RF signal. Optionally, signal processor 101 instructs disarming the alarm system at
313.
[0060] In some embodiments the at least one deception RF signal is protected by an error
detecting code. Optionally, the error detecting code is a 16-bit cyclic-redundancy-check.
In some embodiments the at least one deception RF signal is encrypted. Optionally,
the at least one deception RF signal is encrypted using obfuscation. Optionally, the
at least one deception RF signal is encrypted using exclusive-or with a predefined
seed word or with a random seed word.
[0061] Up to a predetermined number of RF signals received during one or more of the receive
time slots and not recognized as a deception RF signal may be discarded and ignored
by signal processor 101.
[0062] Another possible method to detect an intrusion attempt uses RF imperfections of a
signal. Following is an optional method implemented by the system in some embodiments
of the present invention, to detect an intrusion attempt using RF imperfections of
a signal.
[0063] Reference is now made also to FIG. 4, showing a flowchart schematically representing
an optional flow of operations 400 for detecting an intrusion attempt using RF imperfections
of a signal, according to some embodiments of the present invention. In some embodiments,
a signal transmitted by an alarm control device comprises a sequence of digital bits
encoded in an analog carrier signal. Optionally, the signal comprises a preamble and/or
a code word before a message. Optionally, an RF transceiver 102 receives at 401 a
preamble RF signal from an alarm control device 103. The preamble RF signal comprises
a sequence of preamble digital bits encoded in an analog preamble carrier signal.
Optionally, RF transceiver 102 sends the received preamble RF signal to a signal processor
101 and at 402 signal processor 101 analyzes the preamble RF signal to determine a
plurality of preamble imperfections of the analog preamble carrier signal. Examples
of preamble imperfections are an offset of a frequency of the analog preamble carrier
signal, a phase noise in the analog preamble carrier signal, an IQ imbalance in the
analog preamble carrier signal, and nonlinearity on the analog preamble carrier signal.
For example, a level of sinus signal inaccuracy in the sinuses making up the analog
preamble carrier signal's (that is, an offset of a frequency of the analog preamble
carrier signal) may be expressed as a normalized range of numbers. For example, a
sub-range between 0 and 1, for example 0.7-0.72. At 403, the signal processor optionally
compares the plurality of preamble imperfections to a plurality of reference preamble
imperfections to determine preamble compliance. In some embodiments signal processor
101 uses a correlator having a sample rate of 16 bits per second to compare the plurality
of preamble imperfections to the plurality of reference preamble imperfections. At
404 signal processor 101 optionally selects an alarm system operation to perform according
to the preamble compliance. When the plurality of preamble imperfections do not comply
with the plurality of reference preamble imperfections, signal processor 101 optionally
determines an intrusion attempt at 407. Optionally, signal processor 101 next notifies
a control center 104 at 410. Optionally, at 411 signal processor 101 delivers an electrical
current to one or more alarm devices 105 capable of emitting an audio signal or a
visual signal.
[0064] When the plurality of preamble signal imperfections comply with the reference plurality
of preamble signal imperfections, signal processor 101 optionally determines a valid
message. When a message is received at 408 after determining a valid message, signal
processor 101 at 409 optionally processes the message. When the message is a disarm
message, signal processor 101 optionally instructs disarming the alarm system, for
example by instructing an alarm controller 110.
[0065] Optionally, RF transceiver 102 receives a synchronization word (sync-word) after
the preamble. Reference is now made also to FIG. 5, showing a flowchart schematically
representing another optional flow of operations 500 for detecting an intrusion attempt
using RF signal imperfections of a signal, according to some embodiments of the present
invention. In such embodiments, after receiving the preamble RF signal, signal processor
101 receives via RF transceiver 102 a sync-word RF signal at 501. The sync-word RF
signal comprises a sequence of sync-word digital bits encoded in an analog sync-word
carrier signal. Optionally, at 502 signal processor 101 analyzes the sync-word RF
signal to determine a plurality of sync-word signal imperfections of the analog sync-word
carrier signal. Examples of sync-word signal imperfections are an offset of a frequency
of the analog sync-word carrier signal, a phase noise in the analog sync-word carrier
signal, an IQ imbalance in the analog sync-word carrier signal and nonlinearity on
the analog sync-word carrier signal. For example, a level of sinus signal inaccuracy
in the sinuses making up the analog sync-word carrier signal's (that is, an offset
of a frequency of the analog code-word carrier signal) may be expressed as a range.
For example, a sub-range between 0 and 1, for example 0.7-0.72. At 506, signal processor
101 optionally compares the plurality of sync-word signal imperfections to a plurality
of reference sync-word signal imperfections to determine sync-word compliance. In
some embodiments signal processor 101 uses a correlator having a sample rate of 16
bits per second to compare the plurality of sync-word signal imperfections to the
plurality of reference sync-word signal imperfections. At 503 signal processor 101
optionally selects an alarm system operation to perform according to the sync-word
compliance. When the plurality of sync-word signal imperfections do not comply with
the plurality of reference sync-word signal imperfections, signal processor 101 optionally
determines an intrusion attempt at 407. Optionally, signal processor 101 next notifies
control center 104 at 410. Optionally, at 411 signal processor 101 delivers an electrical
current to one or more alarm devices 105 capable of emitting an audio signal or a
visual signal.
[0066] When the plurality of sync-word signal imperfections comply with the reference plurality
of sync-word signal imperfections, signal processor 101 optionally determines a valid
message. When a message is received at 408 after determining a valid message, signal
processor 101 at 409 optionally processes the message. When the message is a disarm
message, signal processor 101 optionally instructs disarming the alarm system, for
example by instructing alarm controller 110.
[0067] In some other embodiments, signal processor 101 determines a valid message when only
one of the sync-word compliance and preamble compliance is true.
[0068] In some embodiments, reference signal imperfections are produced by analyzing a reference
signal transmitted by an authorized alarm control device. Reference is now made to
FIG. 6, showing a flowchart schematically representing an optional flow of operations
600 for producing reference signal imperfections, according to some embodiments of
the present invention. In such embodiments, signal processor 101 may receive at 601
via RF transceiver 102 a reference RF signal, encoding a sequence of reference digital
bits in an analog reference carrier signal. Signal processor 101 optionally processes
the analog reference carrier signal at 602 to obtain a plurality of reference preamble
signal imperfections, and at 603 optionally stores the plurality of reference preamble
signal imperfections in non-volatile storage 112. Similarly, to produce a plurality
of sync-word signal imperfections, signal processor 101 optionally processes the analog
reference carrier signal at 602 to obtain a plurality of sync-word preamble signal
imperfections, and at 603 optionally stores the plurality of reference sync-word signal
imperfections in non-volatile storage 112.
[0069] Another possible method to detect an intrusion attempt uses unsupported alarm control
device instructions. Following is an optional method implemented by the system in
some embodiments of the present invention, to detect an intrusion attempt using unsupported
alarm control device instructions.
[0070] Reference is now made also to FIGs. 7A and 7B, showing time sequences schematically
representing an optional flow of operations for detecting an intrusion attempt using
an unsupported instruction, according to some embodiments of the present invention.
In such embodiments the alarm control device has a predefined set of supported instructions.
An unsupported instruction is an instruction not in the predefined set of supported
instructions. When the alarm control device receives a signal from the signal processor
instructing an unsupported instruction, the alarm control device optionally transmits
to the signal processor an error RF signal message including an indication of the
unsupported instruction. This protocol is used in some embodiments to create a deception
signal.
[0071] Reference is now made also to FIG. 7A, showing a time sequence schematically representing
an optional flow of operations for detecting an intrusion attempt using an unsupported
instruction with regard to an authorized alarm control device, according to some embodiments
of the present invention. In such embodiments, RF transceiver 702 receives at 710
a first disarm RF signal from an alarm control device 701, and transmits at 711 a
deception RF signal comprising an unsupported instruction X selected from a group
of predefined instructions known to be unsupported by alarm control device 701. Optionally,
unsupported instruction X is selected at random from the group of predefined unsupported
instructions. When alarm control device 701 is authorized, the alarm control device
optionally transmits at 712 an error RF response comprising the unsupported instruction
X received from RF transceiver 702. The RF transceiver optionally sends the error
RF response to signal processor 703 at 713. Optionally, signal processor 703 receives
the error RF response and extracts at 714 the returned unsupported instruction. At
715 signal processor 703 optionally compares the returned unsupported instruction
to the unsupported instruction X. Next, signal processor 703 optionally selects an
alarm system operation to output according to the unsupported instruction compliance.
When the returned unsupported instruction complies with X, for example is equal to
X, at 716 signal processor 703 optionally determines a valid disarm message. Optionally,
at 717 signal processor 703 sends alarm control device 701 via RF transceiver 702
a response RF signal comprising a supported instruction selected from the alarm control
device's predefined set of supported instructions. Optionally, signal processor 703
instructs disarming the alarm system, for example by instructing an alarm controller.
[0072] A sequence of signals including a disarm message and an RF response signal indicating
an erroneous instruction may be recorded and retransmitted by an unauthorized alarm
control device. Reference is now made also to FIG. 7B, showing a time sequence schematically
representing an optional flow of operations for detecting an intrusion attempt using
an unsupported instruction with regard to an unauthorized alarm control device, according
to some embodiments of the present invention. In such embodiments, in response to
received recorded first disarm RF signal at 710, signal processor 703 transmits at
721 a deception RF signal comprising another unsupported instruction Y selected from
a group of predefined instructions known to be unsupported by alarm control device
701. Optionally, unsupported instruction Y is selected at random from the group of
predefined unsupported instructions. When alarm control device 701 is unauthorized,
the alarm control device optionally transmits at 712 a recorded error RF response
comprising the recorded unsupported instruction X. The RF transceiver optionally sends
the error RF response to signal processor 703 at 713. Optionally, signal processor
703 receives the error RF response and extracts at 714 the returned unsupported instruction.
At 715 signal processor 703 optionally compares the returned unsupported instruction
to the unsupported instruction Y. Next, signal processor 703 optionally selects an
alarm system operation to output according to the unsupported instruction compliance.
When the returned unsupported instruction (X) does not comply with Y, for example
is different from Y, at 724 signal processor 703 optionally determines an intrusion
attempt. Optionally, the signal processor next notifies a control center. Optionally,
the signal processor delivers an electrical current to one or more alarm devices capable
of emitting an audio signal or a visual signal.
[0073] Typically, an alarm control device supports only several functions, typically fewer
than 100. When the unsupported instruction is represented by a 16-bit digital word
and an unsupported instruction transmitted by the transceiver to the alarm control
device is selected at random, the probability of selecting the same unsupported instruction
recorded is close to 2^16. Comparing a received unsupported instruction indication
to a transmitted unsupported instruction indication has a high probability of detecting
a recorded error RF signal.
[0074] A possible alarm system comprises at least one radio-frequency (RF) transceiver configured
to receive a preamble RF signal from an alarm control device, the preamble RF signal
comprising a sequence of preamble digital bits encoded in an analog preamble carrier
signal; and at least one signal processor electrically connected to the at least one
RF transceiver, configured to: analyze the preamble RF signal to determine a plurality
of preamble signal imperfections of the analog preamble carrier signal, the preamble
signal imperfections comprising at least one of a frequency imperfection of a sinus
signal, an amplitude imperfection of a sinus signal and a phase imperfection of a
sinus signal; compare the plurality of preamble signal imperfections with a plurality
of reference preamble signal imperfections to determine a preamble compliance; receive
via the at least one RF transceiver a message RF signal from the alarm control device,
the message RF signal comprising a sequence of message digital bits encoded in an
analog message carrier signal; and perform an alarm system operation according to
the preamble compliance.
[0075] Optionally, the at least one signal processor is further configured to determine
an intrusion attempt, subject to at least one of the plurality of preamble signal
imperfections failing to comply with the plurality of reference preamble signal imperfections.
[0076] Optionally, the at least one signal processor is further configured to determine
a valid message subject to the plurality of preamble signal imperfections complying
with the plurality of reference preamble signal imperfections; and wherein the alarm
system operation comprises processing the message RF signal.
[0077] Optionally, the plurality of reference preamble signal imperfections comprises at
least one preamble characteristic selected from the group of: a carrier frequency
offset, a phase noise, an in-phase and quadrature imbalance (IQ imbalance), and a
signal nonlinearity.
[0078] Optionally, the at least one signal processor is further configured to: receive via
the at least one RF transceiver after the preamble signal a synchronization-word (sync-word)
RF signal from the alarm control device, the sync-word RF signal comprising a sequence
of sync-word digital bits encoded in an analog sync-word carrier signal; analyze the
analog sync-word carrier signal to determine a plurality of sync-word signal imperfections
of the sync-word signal, the sync-word signal imperfections comprising at least one
of a frequency imperfection of a sinus signal, an amplitude imperfection of a sinus
signal and a phase imperfection of a sinus signal; compare the plurality of sync-word
signal imperfections with a plurality of reference sync-word signal imperfections
to determine a sync-word compliance; and perform the alarm system operation according
to the preamble compliance and the sync-word compliance.
[0079] Optionally, the at least one signal processor is further configured to determine
an intrusion attempt, subject to at least one of the plurality of sync-word signal
imperfections failing to comply with the plurality of reference sync-word signal imperfections,
or at least one of the plurality of signal imperfections failing to comply with the
plurality of reference signal imperfections.
[0080] Optionally, the at least one signal processor is further configured to determine
a valid message subject to the plurality of preamble signal imperfections complying
with the plurality of reference preamble signal imperfections and the plurality of
sync-word signal imperfections complying with the plurality of reference sync-word
signal imperfection, and the alarm system operation comprises processing the message
RF signal.
[0081] Optionally, the plurality of reference sync-word signal imperfections comprises at
least one sync-word characteristic selected from the group of: a carrier frequency
offset, a phase noise, an IQ imbalance, and a signal nonlinearity.
[0082] Optionally, the alarm system operation comprises notifying a control center comprising
at least one hardware processor upon the attempted intrusion being determined.
[0083] Optionally, the alarm system further comprises a device capable of emitting an audio
signal or a visual signal, electrically connected to the at least one signal processor;
and the alarm system operation comprises delivering an electrical current to the device
upon the attempted intrusion being determined.
[0084] Optionally, the alarm system further comprises a non-volatile digital storage electrically
coupled with the at least one signal processor; and the at least one signal processor
is further configured to: receiving via the at least one RF transceiver a reference
RF signal, encoding a sequence of reference digital bits in an analog reference carrier
signal; process the analog reference carrier signal to obtain the plurality of reference
preamble signal imperfections; and store the reference preamble signal imperfections
in the non-volatile digital storage.
[0085] Optionally, the compare is using a correlator having a sample rate of 16 bits per
second.
[0086] A possible method for an alarm system comprises: receiving a preamble RF signal from
an alarm control device, the preamble RF signal comprising a sequence of preamble
digital bits encoded in an analog preamble carrier signal; analyzing the preamble
RF signal to determine a plurality of preamble signal imperfections of the analog
preamble carrier signal, the preamble signal imperfections comprising at least one
of a frequency imperfection of a sinus signal, an amplitude imperfection of a sinus
signal and a phase imperfection of a sinus signal; comparing the plurality of preamble
signal imperfections with a plurality of reference preamble signal imperfections to
determine a preamble compliance; receiving via the at least one RF transceiver a message
RF signal from the alarm control device, the message RF signal comprising a sequence
of message digital bits encoded in an analog message carrier signal; and performing
an alarm system operation according to the preamble compliance.
[0087] A possible alarm system, comprises at least one radio-frequency (RF) transceiver
configured to: receive a first disarm RF signal from an alarm control device; transmit,
after receiving the first disarm RF signal, a deception RF signal to the alarm control
device, the deception RF signal comprising an unsupported instruction selected from
a group of predefined instructions unsupported by the alarm control device; and receive
an error RF response from said alarm control device, the error RF response comprising
an indication of a returned unsupported instruction; and at least one signal processor
electrically connected to the at least one RF transceiver, configured to: receive
the error RF response from the RF transceiver; extract the returned unsupported instruction
from the error RF response; compare the returned unsupported instruction to the unsupported
instruction to determine a compliance; and output an alarm system operation according
to the compliance.
[0088] Optionally, the at least one signal processor is further configured to determine
an intrusion attempt, subject to the returned unsupported instruction differing from
with the unsupported instruction.
[0089] Optionally, the at least one signal processor is further configured to determine
a valid disarm message subject to subject to the returned unsupported instruction
being equal to the unsupported instruction; and the alarm system operation comprises
at least one of a group of: instructing disarming said alarm system and transmitting
via said at least one RF transceiver a response RF signal comprising a supported instruction.
[0090] Optionally, the alarm system operation comprises notifying a control center comprising
at least one hardware processor upon the attempted intrusion being detected.
[0091] Optionally, the alarm system further comprises a device capable of emitting an audio
signal or a visual signal, electrically connected to the at least one signal processor;
and the alarm system operation comprises delivering an electrical current to the device
upon the attempted intrusion being detected.
[0092] Optionally, the unsupported instruction is selected at random from the group of predefined
instructions; and the unsupported instruction is represented as a 16 bit digital word.
[0093] A possible method for an alarm system comprises: receiving a first disarm RF signal
from an alarm control device; transmitting, after receiving the first disarm RF signal,
a deception RF signal to the alarm control device, the deception RF signal comprising
an unsupported instruction selected from a group of predefined instructions unsupported
by the alarm control device; receiving an error RF response from the alarm control
device, the error RF response comprising an indication of a returned unsupported instruction;
extracting the returned unsupported instruction from the error RF response; comparing
the returned unsupported instruction to the unsupported instruction to determine a
compliance; and outputting an alarm system operation according to the compliance.
[0094] The descriptions of the various embodiments of the present invention have been presented
for purposes of illustration, but are not intended to be exhaustive or limited to
the embodiments disclosed. Many modifications and variations will be apparent to those
of ordinary skill in the art without departing from the scope and spirit of the described
embodiments. The terminology used herein was chosen to best explain the principles
of the embodiments, the practical application or technical improvement over technologies
found in the marketplace, or to enable others of ordinary skill in the art to understand
the embodiments disclosed herein.
[0095] It is expected that during the life of a patent maturing from this application many
relevant alarm control devices will be developed and the scope of the term "alarm
control device" is intended to include all such new technologies a priori.
[0096] As used herein the term "about" refers to ± 10
%.
[0097] The terms "comprises", "comprising", "includes", "including", "having" and their
conjugates mean "including but not limited to". This term encompasses the terms "consisting
of" and "consisting essentially of".
[0098] The phrase "consisting essentially of" means that the composition or method may include
additional ingredients and/or steps, but only if the additional ingredients and/or
steps do not materially alter the basic and novel characteristics of the claimed composition
or method.
[0099] As used herein, the singular form "a", "an" and "the" include plural references unless
the context clearly dictates otherwise. For example, the term "a compound" or "at
least one compound" may include a plurality of compounds, including mixtures thereof.
[0100] The word "exemplary" is used herein to mean "serving as an example, instance or illustration".
Any embodiment described as "exemplary" is not necessarily to be construed as preferred
or advantageous over other embodiments and/or to exclude the incorporation of features
from other embodiments.
[0101] The word "optionally" is used herein to mean "is provided in some embodiments and
not provided in other embodiments". Any particular embodiment of the invention may
include a plurality of "optional" features unless such features conflict.
[0102] Throughout this application, various embodiments of this invention may be presented
in a range format. It should be understood that the description in range format is
merely for convenience and brevity and should not be construed as an inflexible limitation
on the scope of the invention. Accordingly, the description of a range should be considered
to have specifically disclosed all the possible subranges as well as individual numerical
values within that range. For example, description of a range such as from 1 to 6
should be considered to have specifically disclosed subranges such as from 1 to 3,
from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual
numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless
of the breadth of the range.
[0103] Whenever a numerical range is indicated herein, it is meant to include any cited
numeral (fractional or integral) within the indicated range. The phrases "ranging/ranges
between" a first indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are used herein interchangeably
and are meant to include the first and second indicated numbers and all the fractional
and integral numerals therebetween.
[0104] It is appreciated that certain features of the invention, which are, for clarity,
described in the context of separate embodiments, may also be provided in combination
in a single embodiment. Conversely, various features of the invention, which are,
for brevity, described in the context of a single embodiment, may also be provided
separately or in any suitable subcombination or as suitable in any other described
embodiment of the invention. Certain features described in the context of various
embodiments are not to be considered essential features of those embodiments, unless
the embodiment is inoperative without those elements.
[0105] All publications, patents and patent applications mentioned in this specification
are herein incorporated in their entirety by reference into the specification, to
the same extent as if each individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein by reference. In
addition, citation or identification of any reference in this application shall not
be construed as an admission that such reference is available as prior art to the
present invention. To the extent that section headings are used, they should not be
construed as necessarily limiting.
[0106] It will be understood that the invention has been described above purely by way of
example, and modifications of detail can be made within the scope of the invention.
[0107] Each feature disclosed in the description, and (where appropriate) the claims and
drawings may be provided independently or in any appropriate combination.
[0108] Reference numerals appearing in the claims are by way of illustration only and shall
have no limiting effect on the scope of the claims.
1. An alarm system (100), comprising:
at least one radio-frequency (RF) transceiver (102) configured to:
receive a first disarm RF signal (201) from an alarm control device (103);
during a predetermined delay time after receiving said first disarm RF signal, transmit
at least one deception RF signal (220) during one or more transmission time slots
selected from a plurality of consecutive time slots of said predetermined delay time,
and determine whether one or more receive RF signals (250) are received during one
or more receiving time slots selected from said plurality of consecutive time slots,
said one or more receiving time slots interleaved with said one or more transmission
time slots; and
at least one signal processor (101), electrically connected to said at least one RF
transceiver, configured to:
determine an alarm system operation according to analysis of said one or more receive
RF signals.
2. The system (100) of claim 1, wherein said analysis comprises:
matching at least one of said one or more receive RF signals (250) with a predefined
deception signal pattern;
producing a true deception detection indication for each one of said one or more receive
RF signals matching said predefined deception signal pattern; and
selecting said alarm system operation according to said true deception detection indication.
3. The system (100) of claim 1 or 2, wherein said analysis comprises:
producing a false deception detection indication subject to none of said one or more
receive RF signals (250) being received during said one or more receiving time slots
or each one of said one or more receive RF signals failing to match said predefined
deception signal pattern ; and
selecting said alarm system operation according to said false deception detection
indication.
4. The system (100) of any preceding claim, wherein said at least one signal processor
(101) is further configured to:
determine said first disarm RF signal (201) is valid, subject to not receiving any
of said one or more receive RF signals (250) or producing only false deception detection
indication; and
receive a second disarm RF signal (202) from said alarm control device (103) after
said predetermined delay time;
wherein, upon receiving said second disarm RF signal, said alarm system operation
comprises at least one of: instructing disarming said alarm system, and transmitting
an acknowledgement RF signal to said alarm control device via said at least one RF
transceiver (102).
5. The system (100) of any preceding claim, wherein said transmission time slots are
selected at random by said signal processor (101) upon reception of said first disarm
RF signal (201) for transmitting said at least one deception RF signal (220); and
wherein said reception time slots comprise all of said plurality of consecutive time
slots different from said transmission time slots.
6. The system (100) of any preceding claim, wherein an amount of said transmission time
slots is between 15% and 30% of an amount of said plurality of consecutive time slots.
7. The system (100) of any preceding claim, wherein said predetermined delay time is
partitioned into 25 consecutive time slots.
8. The system (100) of any preceding claim,, wherein at least one deception RF signal
(220) comprises at least one of: an identifier, a time stamp and a random number,
for use in identifying an origin of a recorded deception RF signal.
9. The system (100) of claim 8, wherein said identifier consists of 32 binary bits,
wherein said time stamp consists of 32 binary bits, and
wherein said random number consists of 8 binary bits.
10. The system (100) of claim 8 or 9, wherein said matching said predefined deception
signal pattern comprises detecting in said one received RF signal (250) at least one
of: an identifier, a time stamp and a random number.
11. The system (100) of any preceding claim, wherein said at least one deception RF signal
(220) is protected by an error detecting code being a 16-bit cyclic redundancy check.
12. The system (100) of any preceding claim, wherein said at least one deception RF signal
(220) is encrypted using a method selected from the group of: obfuscation, exclusive-or
with a predefined seed word, and exclusive-or with a random seed word.
13. The system (100) of any preceding claim,, wherein said analysis further comprises:
detecting a packet number in said first disarm RF signal (201);
comparing a difference between said packet number and a previously stored packet number
with a predefined threshold number; and
producing a true deception detection indication when said difference is greater than
said predefined threshold number.
14. The system (100) of any preceding claim,, wherein said alarm system operation comprises
at least one operation selected from the group comprising: notifying a control center
(104) operatively connected to said at least one signal processor (101) of an attempted
intrusion, subject to producing at least one true deception detection indication and
delivering an electrical current to a device (105) capable of emitting an audio signal
or a visual signal, electrically connected to said at least one signal processor (101),
subject to producing at least one true deception detection indication.
15. A method for an alarm system (100), comprising:
receiving a first disarm RF signal (201) from an alarm control device (103);
during a predetermined delay time after receiving said first disarm RF signal, transmitting
at least one deception RF signal (220) during one or more transmission time slots
selected from a plurality of consecutive time slots of said predetermined delay time,
and determining whether one or more receive RF signals (250) are received during one
or more receiving time slots selected from said plurality of consecutive time slots,
said one or more receiving time slots interleaved with said one or more transmission
time slots; and
determining an alarm system operation according to analysis of said one or more receive
RF signals.
1. Alarmsystem (100), umfassend:
mindestens einen Hochfrequenz (HF)-Sender-Empfänger (102), der ausgelegt ist zum:
Empfangen eines ersten Entschärfungs-HF-Signals (201) von einer Alarmsteuervorrichtung
(103);
während einer vorbestimmten Verzögerungszeit nach dem Empfangen des ersten Entschärfungs-HF-Signals,
Übertragen mindestens eines Täuschungs-HF-Signals (220) während eines oder mehrerer
Übertragungszeitschlitzen, ausgewählt aus mehreren aufeinanderfolgenden Zeitschlitzen
der vorbestimmten Verzögerungszeit, und Bestimmen, ob ein oder mehrere Empfangs-HF-Signale
(250) während eines oder mehrerer Empfangszeitschlitze, ausgewählt aus den mehreren
aufeinanderfolgenden Zeitschlitzen, empfangen werden, wobei der eine oder die mehreren
Empfangszeitschlitze mit dem einen oder den mehreren Übertragungszeitschlitzen verschachtelt
sind; und
mindestens einen Signalprozessor (101), der elektrisch mit dem mindestens einen HF-Sender-Empfänger
verbunden ist und ausgelegt ist zum:
Bestimmen eines Alarmsystem-Betriebs gemäß der Analyse des einen oder der mehreren
Empfangs-HF-Signale.
2. System (100) nach Anspruch 1, wobei die Analyse umfasst:
Anpassen mindestens eines der einen oder mehreren Empfangs-HF-Signale (250) mit einem
vordefiniertes Täuschungssignalmuster;
Erzeugen einer echten Täuschungsdetektionsanzeige für jedes der einen oder mehreren
Empfangs-HF-Signale, die dem vordefinierten Täuschungssignalmuster entsprechen; und
Auswählen des Alarmsystembetriebs gemäß der Anzeige für die Erkennung wahrer Täuschung.
3. System (100) nach Anspruch 1 oder 2, wobei die Analyse umfasst:
Erzeugen einer Anzeige zur Erkennung falscher Täuschung, wenn keines der einen oder
mehreren Empfangs-HF-Signale (250) während des einen oder der mehreren Empfangszeitschlitze
empfangen wird oder jedes der einen oder mehreren Empfangs-HF-Signale nicht dem vordefinierten
Täuschungssignalmuster entspricht; und
Auswählen des Alarmsystembetriebs gemäß der Anzeige zur Erkennung falscher Täuschung.
4. System (100) von einem der vorhergehenden Ansprüche, wobei der mindestens eine Signalprozessor
(101) ferner ausgelegt ist zum:
Bestimmen, dass das erste Entschärfungs-HF-Signal (201) gültig ist, vorbehaltlich
des Nicht-Empfangs eines oder mehrerer Empfangs-HF-Signale (250) oder der Erzeugung
einer nur falschen Täuschungserkennungsanzeige; und
Empfangen eines zweiten Entschärfungs-HF-Signals (202) von der Alarmsteuervorrichtung
(103) nach der vorbestimmten Verzögerungszeit;
wobei nach dem Empfangen des zweiten Entschärfungs-HF-Signals der Betrieb des Alarmsystems
umfasst: Anweisen des Entschärfens des Alarmsystems und/oder Übertragen eines Bestätigungs-HF-Signals
an die Alarmsteuervorrichtung über den mindestens einen HF-Sender-Empfänger (102).
5. System (100) nach einem der vorhergehenden Ansprüche, wobei die Übertragungszeitschlitze
nach dem Zufallsprinzip durch den Signalprozessor (101) beim Empfang des ersten Entschärfungs-HF-Signals
(201) zum Übertragen des mindestens einen Täuschungs-HF-Signals (220) ausgewählt werden;
und
wobei die Empfangszeitschlitze alle der mehreren aufeinanderfolgenden Zeitschlitze
umfassen, die sich von den Übertragungszeitschlitzen unterscheiden.
6. System (100) nach einem der vorhergehenden Ansprüche, wobei eine Menge der Übertragungszeitschlitze
zwischen 15% und 30% einer Menge der mehreren aufeinanderfolgenden Zeitschlitze beträgt.
7. System (100) nach einem der vorhergehenden Ansprüche, wobei die vorbestimmte Verzögerungszeit
in 25 aufeinanderfolgende Zeitschlitze unterteilt ist.
8. System (100) nach einem der vorhergehenden Ansprüche, wobei mindestens ein Täuschungs-HF-Signal
(220) umfasst: eine Kennung und/oder einen Zeitstempel und/oder eine Zufallszahl zur
Verwendung beim Identifizieren eines Ursprungs eines aufgezeichneten Täuschungs-HF-Signals.
9. System (100) nach Anspruch 8, wobei die Kennung aus 32 binären Bits besteht, wobei
der Zeitstempel aus 32 binären Bits besteht, und
wobei die Zufallszahl aus 8 binären Bits besteht.
10. System (100) nach Anspruch 8 oder 9, wobei das Anpassen des vordefinierten Täuschungssignalmusters
das Erfassen in dem einen empfangenen HF-Signal (250) umfasst: eine Kennung und/oder
einen Zeitstempel und/oder eine Zufallszahl.
11. System (100) nach einem der vorhergehenden Ansprüche, wobei das mindestens eine Täuschungs-HF-Signal
(220) durch einen Fehlererkennungscode geschützt ist, der eine 16-Bit zyklische Redundanzprüfung
ist.
12. System (100) nach einem der vorhergehenden Ansprüche, wobei das mindestens eine Täuschungs-HF-Signal
(220) unter Verwendung eines Verfahrens verschlüsselt wird, das aus folgender Gruppe
ausgewählt ist: Verschleierung, Exklusiv oder mit einem vordefinierten Startwort und
Exklusiv oder mit einem zufälligen Startwort.
13. System (100) nach einem der vorhergehenden Ansprüche, wobei die Analyse ferner umfasst:
Erfassen einer Paketnummer in dem ersten Entschärfungs-HF-Signal (201);
Vergleichen eines Unterschieds zwischen der Paketnummer und einer zuvor gespeicherten
Paketnummer mit einer vordefinierten Schwellenwertnummer; und
Erzeugen einer echten Täuschungserfassungsanzeige, wenn der Unterschied größer als
die vordefinierte Schwellenwertzahl ist.
14. System (100) nach einem der vorhergehenden Ansprüche, wobei der Betrieb des Alarmsystems
mindestens einen Betrieb umfasst, der aus der folgenden Gruppe ausgewählt ist:
Benachrichtigen einer Steuerzentrale (104), die funktionsfähig mit dem mindestens
einen Signalprozessor (101) verbunden ist, über einen versuchten Einbruch, vorbehaltlich
des Erzeugens mindestens einer echten Täuschungserfassungsanzeige und des Liefern
eines elektrischen Stroms an eine Vorrichtung (105), die in der Lage ist, ein Audiosignal
oder ein visuelles Signal zu emittieren, die elektrisch mit dem mindestens einen Signalprozessor
(101) verbunden ist, vorbehaltlich des Erzeugens mindestens einer wahren Täuschungserfassungsanzeige.
15. Verfahren für ein Alarmsystem (100), umfassend:
Empfangen eines ersten Entschärfungs-HF-Signals (201) von einer Alarmsteuervorrichtung
(103);
während einer vorbestimmten Verzögerungszeit nach dem Empfangen des ersten Entschärfungs-
HF-Signals, Übertragen mindestens eines Täuschungs-HF-Signals (220) während eines
oder mehrerer Übertragungszeitschlitze, ausgewählt aus mehreren aufeinanderfolgenden
Zeitschlitzen der vorbestimmten Verzögerungszeit, und Bestimmen, ob ein oder mehrere
Empfangs-HF-Signale (250) während eines oder mehrerer Empfangszeitschlitze, ausgewählt
aus den mehreren aufeinanderfolgenden Zeitschlitzen, empfangen werden, wobei der eine
oder die mehreren Empfangszeitschlitze mit dem einen oder den mehreren Übertragungszeitschlitzen
verschachtelt sind; und
Bestimmen eines Alarmsystem-Betriebs gemäß der Analyse des einen oder der mehreren
Empfangs-HF-Signale.
1. Système d'alarme (100), comprenant :
au moins un émetteur-récepteur (102) radiofréquence (RF) configuré pour :
recevoir un premier signal RF de désarmement (201) en provenance d'un dispositif de
commande d'alarme (103) ;
pendant un temps de retard prédéterminé après réception dudit premier signal RF de
désarmement, émettre au moins un signal RF de dissimulation (220) pendant un ou plusieurs
créneaux temporels d'émission sélectionnés parmi une pluralité de créneaux temporels
consécutifs dudit temps de retard prédéterminé, et déterminer si un ou plusieurs signaux
RF de réception (250) sont reçus pendant un ou plusieurs créneaux temporels de réception
sélectionnés parmi ladite pluralité de créneaux temporels consécutifs, lesdits un
ou plusieurs créneaux temporels de réception étant entrelacés avec lesdits un ou plusieurs
créneaux temporels d'émission ; et
au moins un processeur de signal (101), électriquement connecté audit au moins un
émetteur-récepteur RF, configuré pour :
déterminer une opération du système d'alarme conformément à une analyse desdits un
ou plusieurs signaux RF de réception.
2. Système (100) selon la revendication 1, dans lequel ladite analyse consiste à :
mettre en correspondance au moins l'un desdits un ou plusieurs signaux RF de réception
(250) avec un motif de signal de dissimulation prédéfini ;
produire une indication de vraie détection de dissimulation pour chacun desdits un
ou plusieurs signaux RF de réception correspondant audit motif de signal de dissimulation
prédéfini ; et
sélectionner ladite opération du système d'alarme conformément à ladite indication
de vraie détection de dissimulation.
3. Système (100) selon la revendication 1 ou 2, dans lequel ladite analyse consiste à
:
produire une indication de fausse détection de dissimulation sous réserve qu'aucun
desdits un ou plusieurs signaux RF de réception (250) ne soit reçu pendant lesdits
un ou plusieurs créneaux temporels de réception ou que chacun desdits un ou plusieurs
signaux RF de réception ne correspondent pas audit motif de signal de dissimulation
prédéfini ; et
sélectionner ladite opération du système d'alarme conformément à ladite indication
de fausse détection de dissimulation.
4. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ledit
au moins un processeur de signal (101) est en outre configuré pour :
déterminer que ledit premier signal RF de désarmement (201) est valide, sous réserve
de ne recevoir aucun desdits un ou plusieurs signaux RF de réception (250) ou de ne
produire qu'une indication de fausse détection de dissimulation ; et
recevoir un second signal RF de désarmement (202) en provenance dudit dispositif de
commande d'alarme (103) après ledit temps de retard prédéterminé ;
dans lequel, lors de la réception dudit second signal RF de désarmement, ladite opération
du système d'alarme comprend au moins l'une des opérations suivantes : ordonner le
désarmement dudit système d'alarme, et transmettre un signal RF d'acquittement audit
dispositif de commande d'alarme par l'intermédiaire dudit au moins un émetteur-récepteur
RF (102).
5. Système (100) selon l'une quelconque des revendications précédentes, dans lequel lesdits
créneaux temporels d'émission sont sélectionnés aléatoirement par ledit processeur
de signal (101) lors de la réception dudit premier signal RF de désarmement (201)
pour émettre ledit au moins un signal RF de dissimulation (220) ; et
dans lequel lesdits créneaux temporels de réception comprennent la totalité de ladite
pluralité de créneaux temporels consécutifs différents desdits créneaux temporels
d'émission.
6. Système (100) selon l'une quelconque des revendications précédentes, dans lequel une
quantité desdits créneaux temporels d'émission est comprise entre 15% et 30% d'une
quantité de ladite pluralité de créneaux temporels consécutifs.
7. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ledit
temps de retard prédéterminé est divisé en 25 créneaux temporels consécutifs.
8. Système (100) selon l'une quelconque des revendications précédentes, dans lequel au
moins un signal RF de dissimulation (220) comprend au moins l'un :
d'un identificateur, d'un marqueur temporel et d'un nombre aléatoire, destinés à être
utilisés pour identifier l'origine d'un signal RF de dissimulation enregistré.
9. Système (100) selon la revendication 8, dans lequel ledit identificateur est constitué
de 32 bits binaires, dans lequel ledit marqueur temporel est constitué de 32 bits
binaires, et dans lequel ledit nombre aléatoire est constitué de 8 bits binaires.
10. Système (100) selon la revendication 8 ou 9, dans lequel ladite mise en correspondance
dudit motif de signal de dissimulation prédéfini consiste à détecter dans ledit un
signal RF reçu (250) au moins l'un : d'un identificateur, d'un marqueur temporel et
d'un nombre aléatoire.
11. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ledit
au moins un signal RF de dissimulation (220) est protégé par un code de détection
d'erreur qui est un contrôle de redondance cyclique à 16 bits.
12. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ledit
au moins un signal RF de dissimulation (220) est crypté à l'aide d'un procédé choisi
dans le groupe comprenant : un obscurcissement, un ou exclusif avec un mot de germe
prédéfini, et un ou exclusif avec un mot de germe aléatoire.
13. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ladite
analyse consiste en outre à :
détecter un nombre de paquets dans ledit premier signal RF de désarmement (201) ;
comparer une différence entre ledit nombre de paquets et un nombre de paquets précédemment
stocké à un nombre seuil prédéfini ; et
produire une indication de vraie détection de dissimulation lorsque ladite différence
est supérieure audit nombre seuil prédéfini.
14. Système (100) selon l'une quelconque des revendications précédentes, dans lequel ladite
opération du système d'alarme comprend au moins une opération sélectionnée dans le
groupe comprenant :
le signalement à un centre de commande (104) fonctionnellement connecté audit au moins
un processeur de signal (101) d'une tentative d'intrusion, sous réserve de produire
au moins une indication de vraie détection de dissimulation et la fourniture d'un
courant électrique à un dispositif (105) capable d'émettre un signal audio ou un signal
visuel, qui est électriquement connecté audit au moins un processeur de signal (101),
sous réserve de produire au moins une indication de vraie détection de dissimulation.
15. Procédé destiné à un système d'alarme (100), consistant à :
recevoir un premier signal RF de désarmement (201) en provenance d'un dispositif de
commande d'alarme (103) ; pendant un temps de retard prédéterminé après réception
dudit premier signal RF de désarmement, émettre au moins un signal RF de dissimulation
(220) pendant un ou plusieurs créneaux temporels d'émission sélectionnés parmi une
pluralité de créneaux temporels consécutifs dudit temps de retard prédéterminé, et
déterminer si un ou plusieurs signaux RF de réception (250) sont reçus pendant un
ou plusieurs créneaux temporels de réception sélectionnés parmi ladite pluralité de
créneaux temporels consécutifs, lesdits un ou plusieurs créneaux temporels de réception
étant entrelacés avec lesdits un ou plusieurs créneaux temporels d'émission ; et
déterminer une opération du système d'alarme conformément à une analyse desdits un
ou plusieurs signaux RF de réception.