[0001] The present invention relates to apparatus and methods for detecting use of mobile
communications equipment in moving vehicles. In particular, it relates to method and
apparatus for detecting traffic violations associated with use of mobile communications
in moving vehicles, and , in greatest particularity, is aimed at, but not exclusive
to, detection of the use of mobile telephones in such circumstances.
[0002] Road traffic authorities and police forces are becoming increasingly anxious about
the deleterious effects on driving standards caused by the use of communications equipment,
by a vehicle driver, when the vehicle is in motion. Loss of road-related concentration,
by the driver, as the driver concentrates on the content of the communication, is,
if statistics are to be believed, a contributory, if not an exclusive, cause of a
significant proportion of road traffic accidents. As a consequence, in many jurisdictions,
it has become a moving traffic violation to be proved to be engaged in radio communications
while driving a vehicle.
[0003] A particular problem arises with mobile telephones. Nearly all manufacturers provide
a "hands free" kit whereby a telephone conversation can be conducted without the user
requiring to hold the telephone. Even this is frowned upon by some traffic authorities
because a loss of road concentration has been shown to ensue simply as a result of
concentrating on the call. Anyone familiar with present road conditions will be painfully
aware that a very high proportion of in-vehicle mobile telephone users do not employ
a hands free kit, but simply hold the mobile telephone to their head, while driving
with one free hand. This results in reduced ability to control the vehicle, should
the telephone user be the driver. Worse still, some mobile telephone users cradle
the telephone between their shoulder and their tilted head. If the mobile telephone
user is a driver, the restriction in head mobility and hence road visibility can have
catastrophic consequences.
[0004] Enforcement of restrictions on mobile telephone use is very difficult. Conclusive
evidence that a mobile telephone was in use by a driver, even at the time of an accident,
is hard to acquire. The present invention seeks to provide a means for establishing
use, by a driver, of mobile communications equipment, in a moving vehicle, with sufficient
certainty to bring a caution of conviction, should the authorities so require or desire.
[0005] An apparatus for providing evidence of use of mobile communications in a vehicle,
characterised in that there is provided: a monitor (14) for monitoring emission of
radio signals from the vehicle and operative to provide output indicative thereof;
a controller (26,32), coupled to receive said output from said monitor and operative
to determine whether or not emitted radio signals, from the vehicle, have characteristics
indicative of at least one type, from a predetermined set of types, of mobile communications
activity is in progress in the vehicle; and a camera, (24) operative to acquire an
image of the vehicle, and coupled to be triggered by said controller (32) in the event
that said controller determines that said at least one type of mobile communications
activity is in progress in the vehicle.
[0006] An apparatus, according to claim 1, wherein said monitor (14) comprises a directional
antenna (14) to be aimed at the vehicle, and a radio receiver (26,32,52), operative
to receive signals from said antenna and to demodulate and measure the strength of
signals from said antenna.
By acquiring an image of the vehicle, at the moment of communications use, the present
invention seeks to provide visual evidence which can be used to establish if the driver
was the sole occupant of the vehicle, if the driver, if sole, was employing a hands
free method of communication, if the driver was not the sole vehicle occupant but
was nonetheless visibly engaged in mobile communications, or if there was a certainty
or high probability that another person, in the vehicle, was in fact the communications
user.
[0007] The various aspects provide, for preference, for use of a directional antenna to
be aimed at the vehicle, and a radio receiver, to receive signals from the antenna
and to demodulate and measure the strength of signals from the antenna.
[0008] In this manner, invention seeks to provide, for strong forensic proof, that the individual
vehicle, and no other, is the sole target for monitoring.
[0009] The various aspects further provide for responding to the indication of measured
strength of the signal from the antenna to determine, in a first stage, by a first
criterion, if a predetermined signal strength has been exceeded; and, if the predetermined
signal strength has been exceeded, in a second stage, analysing the demodulated signal
to determine the nature of the signal and to determine, by a second criterion, if
the signal belongs to at least one type of the predetermined set of types of mobile
communications activity , the image being acquired or the camera being triggered if
the first and second criteria are fulfilled. In this manner, a picture is taken of
the vehicle if and only if a targeted type of mobile communications activity is sure
to be taking place in the vehicle.
[0010] In this manner, the invention seeks to provide that a very high probability, or certainty,
of use of mobile communications equipment exists before any action is initiated. Further,
by analysing the type of communications activity, the invention seeks to provide further
forensic certainty through the signal style being identified and matched, if required,
against the type of communications equipment in the vehicle.
[0011] The range of signal strengths can be very large. A mobile telephone, close to a receiver
and generating full power, can easily overload the receiver. On the other hand, even
weak signals require to be monitored on occasions. The range of signal strengths is
enormous. Forensic certainty requires that the invention always functions in a correct
manner, and cannot be overloaded.
[0012] To this end, the various aspects of the invention provide that the receiver comprises
plural automatic gain control amplifier stages for accommodating the wide range of
signal strengths from the antenna, and further provides that the analysis of the type
of radio communications activity involves feedback to control the gain of at least
one of the stages. In this manner the invention seeks to ensure proper linearity of
the analysis by keeping signal levels within acceptable ranges of amplitude.
[0013] Band planning ensures that mobile communications occur on a limited number of frequency
band allocations. For example, at the present time most mobile telephones are to be
found, in the United Kingdom, around 900 MHz and 1800 MHz, while PMR (private mobile
radio) and amateur radio is to be found on a scattering of bands in the VHF and UHF
allocations. It would result in a degradation of the quality of evidence due to unwanted
radio interference, and possible "false detection", if a wide band approach were adopted.
[0014] The various aspects of the present invention seek to overcome this objection by providing
that the receiver is band limited to receive only that band or those bands of radio
signals wherein the predetermined set of types of mobile communications activity are
expected to occur.
[0015] For further forensic benefit, the various aspects of the invention provide that,
when triggering the camera or acquiring the image, details are appended to the acquired
image, indicative of the type and time of detected radio communications activity.
This seeks to strengthen the evidential value of any image, later relied upon for
proof.
[0016] In one preferred embodiment of the invention, the various aspects of the invention
provide for incorporation in a portable apparatus where the antenna can be pointed
into the path of an oncoming vehicle. In this manner, the invention seeks to provide
means, much like the "speed guns", employed to detect speeding drivers, but directed
to the purpose of the invention.
[0017] In another preferred embodiment of the invention, the various aspects provide that
the antenna is suspended above a road surface. This permits the invention to be installed
on existing structures, such as highway bridges or gantries, and existing power sources
and resources where present.
[0018] In another preferred embodiment of the invention, the various aspects provide that
image acquisition is achieved by a camera, which provides a secondary function as
a roadway speed detection camera. In this manner the present invention seeks two advantages.
Firstly, since speed detection cameras automatically append time and vehicle speed
indication to an acquired image, and show vehicle registration plates, evidence is
provided that the vehicle was actually in motion at the time of mobile communications
use and substantiate identification. Secondly, since many speed detection cameras
already exist on roads and highways, there is the economic possibility of installing
the invention in association with already present cameras and simply giving a secondary
source of triggering to the speed detection camera.
[0019] The various aspects of the invention further provide that the predetermined set of
types of radio communications activity includes the use of one or more types of mobile
telephone, in which case the one or more types of mobile telephone include one or
more of types using TDMA, CDMA, or GSM. In this manner, the invention seeks to target
the main cause of concern over mobile communications from moving vehicles.
[0020] Where targeted types of mobile communications activity exist on separate bands of
frequencies, it is again a source of detection error if the signals from two or more
bands are allowed to interfere with each other. To overcome this problem the various
aspects of the present invention provide that, where the predetermined set of bands
whereon the predetermined set of types of radio communications activity are expected
to occur comprises a plurality of bands, the receiver switches from one to another
of the plurality of bands. In this manner, the present invention seeks to provide
accurate and proper analysis of radio emissions in each band in turn..
[0021] While the various aspects and features of the invention, as so far described, allow
for the forensically sound acquisition of an image of a vehicle wherein targeted mobile
communications activity is in progress, the invention further seeks to provide utility
by enabling improved administrative process, or instant or rapid action to be taken
on the basis of the acquired image.
[0022] To this end, the various aspects of the invention provide that the acquired image
can be transmitted to another location.
[0023] By this means, the image can be sent to a waiting enforcement vehicle, which can
catch the violator in the act and, if required, levy an instant penalty. Equally,
the image can be sent ahead to a highway toll station, where a ticket of instant penalty
can be imposed. In a similar vein, the image can be sent directly to an administrative
centre where data processing can be used to commence any penalty procedure.
[0024] The invention is further described, by way of example, by the following description,
taken in association with the appended drawings, in which:
[0025] Figure 1 is a projected view of one embodiment of the invention, installed on a highway
gantry and illustrating various aspects thereof.
[0026] Figure 2 is a schematic diagram of the various parts of a first illustrative form
of the invention, functioning according to a plural band requirement.
[0027] Figure 3 is a schematic diagram of a second illustrative form of the invention, functioning
according to a simplified, lower cost and lower performance single band requirement.
[0028] Figure 4 is a flow chart giving an example of the control activities, which take
place within the embodiments of figures 2 and 3.
and
[0029] Figure 5 is a projected view of one manner in which the invention can be incorporated
into a portable apparatus.
[0030] Referring to Figure 1, a gantry 10, across a highway 12, supports a plurality of
radio antennas 14, for monitoring radio signals from vehicles passing the gantry each
antenna 14 having a directional cone of coverage 16 restricted to a part (in this
case a lane 18) of the highway 12 and facing oncoming traffic 20 . The antennas 14
can comprise directional reflectors, absorbent beam-limiting baffles, phased active
or parasitic arrays, or any combination of any known technique. All that is required
of the antennas 14, within the present invention, is that the cone 16 of coverage
should be directional. In particular, it is desirable that the directionality of the
cone 16 should provide significant attenuation to any competing fixed sources of potentially
interfering radio signals, such as a mobile telephone base station 22, which has the
potential to generate blocking and radio super heterodyne image interference (not
to be confused with the visual image, hereafter described)
[0031] Also mounted on the gantry 10 is a camera 24, facing the oncoming traffic 20. In
one preferred embodiment, the camera 24 is simply an already existing speed detection
camera, which is further triggered by detection of mobile phone activity in the oncoming
traffic 20. In a second preferred embodiment, the camera 24 is a dedicated part of
the invention, similarly triggered. The manner of triggering the camera is described
below. When triggered, the camera 24 acquires an image of the front of the oncoming
vehicle 20 where the potential exists to record the identity of the vehicle 20 and
the identity and activity of the driver.
[0032] The camera 10 can be a simple photographic film camera, or a video camera, or a digital
stills picture camera. According to the present invention, all that is required of
the camera 24 is that it can acquire an image which is capable of storage and, for
preference, can be transmitted to another location. For preference again, the acquired
image should be capable of having evidential data added or appended thereto.
[0033] Attention is next drawn to Figure 2, showing a schematic diagram of the functional
elements of a plural band embodiment of the invention.
[0034] A first radio frequency front end 26A receives signals in the range 1800 MHz to 1900
MHz, corresponding to current transmission frequency allocations for one group of
subscriber units (mobile telephones). Equally, a second radio frequency front end
26B receives signals in the range 800 MHz to 900 MHz, corresponding to a second current
transmission frequency allocation for another group of subscriber units. While only
two front ends 26A 26B are shown in Figure 2, the present invention also encompasses
the presence of three or more front ends 26. The invention, described in Figures 2,
shows the front ends 26A 26B being switched at an intermediate frequency. It is to
be understood that the front ends 26A 26B can also be switched at radio frequency.
One beneficial embodiment includes front ends 26 having frequency ranges of 2400 MHz
to 2500 MHz and 5725 MHz to 5875 MHz.
[0035] Each front end 26A 26B comprises a respective mechanical or passive electrical first
band pass filter 28A 28B which limits unwanted signals presented to a respective low
noise amplifier (LNA) 30A 30B which receives an automatic gain control signal (LNA
GAIN CNTL) from a processor 32, whose function is further described below. After the
respective low noise amplifiers 30A 30B, the respective signals are provided to a
second respective band pass filter 34A 34B and then to a respective radio frequency
mixer 36A 36B which is provided with a respective beat frequency oscillation from
a respective radio frequency variable frequency oscillator (RF VCO) 38A 38B, each
controlled by a respective synthesiser 40A 40B which, in turn, derives its frequency
reference from a respective crystal oscillator (TCXO) 42A 42B. The respective radio
frequency mixers 36A 36 B each generate an intermediate frequency centred on 280MHz
which is filtered by respective third band pass filters 44A 44B. This choice of intermediate
frequency ensures acceptable radio super heterodyne image rejection.
[0036] Each front end 26A 26B further comprises a respective intermediate frequency variable
frequency oscillator (IF VCO) 46A 46B, used, as later described, to beat the intermediate
frequency signal down to base band, and locked in sympathy with their respective radio
frequency variable frequency oscillators 38A 38B at twice the intermediate frequency
for phase and quadrate demodulation, as described below.
[0037] The outputs of the respective third band pass filters 44A 44B are coupled as respective
first and second inputs to a first intermediate frequency switch 48, operated by the
controller 32 (via signal X) to select either the output of the first front end 26A,
or the output of the second front end 26B, for provision to a fourth band pass filter
50 whose output provides input to an intermediate frequency stage 52 at a second gain
controlled amplifier 54 which in turn provides input to a phase demodulator 56 and
a quadrate demodulator 58. Phase and quadrate demodulation are here used together
to improve the signal to noise ratio and resolution over that which would be obtained
using a single demodulator,
[0038] The output of the first front end intermediate frequency variable frequency oscillator
46A is coupled as a first input to a second intermediate frequency switch 60. The
output of the second front end intermediate frequency variable frequency oscillator
46B is coupled as a second input to the second intermediate frequency switch 60. The
second intermediate frequency switch 60 is controlled by the processor 32 (via signal
X) in sympathy with the first intermediate frequency switch 48 such that, when the
output from the first front end 26A is coupled as the input to the fourth band pass
filter 50, the output from the first front end intermediate frequency variable frequency
oscillator 46A is coupled as the output of the second intermediate frequency switch
60, and when the output of the second front end 26B is coupled as the input to the
fourth band pass filter 50, the output of the second front end intermediate frequency
variable frequency oscillator 46B is coupled as the output of the second intermediate
frequency switch 60. The front ends 26A 26B thus provide their respective outputs,
together with the outputs of their respective intermediate frequency variable frequency
oscillators 46A 46B, in turn, to the intermediate frequency stage as the controller
32 causes switching between them (via signal X).
[0039] The output of the second intermediate frequency switch 60 is first divided by two
at 62 to bring it down to the intermediate frequency and reduce oscillator phase noise
and then provided directly as input to the phase demodulator 56, and, after a ninety
degree phase shift 64, as input to the quadrate demodulator 58. The phase and quadrate
demodulators each beat the intermediate frequency down to base band with a spectrum
stretching from DC to 8.8 MHz. The outputs of the phase 56 and quadrate 58 demodulators
are provided as input to respective low pass filters 66A 66B each with cut off frequency
of 8.8 MHz, and thence as input to respective phase 68A and quadrate 68B analogue
to digital converters whose outputs, a sequence of digital representations of the
instant amplitude of their analogue inputs, are coupled as selectable inputs to the
bus of the processor 32.
[0040] An analogue indication of the coarse received signal strength (RSSI), as determined
by the measurement of current passing through the second gain control amplifier 54,
is converted by a signal strength analogue to digital converter 70 into digital form,
in turn coupled as a selectable input to the bus of the controller 32.
[0041] Bus buffers 72 receive and hold instructions from the bus of the controller 32, in
particular the gain control signal (LNA GAIN CTRL) for the respective low noise amplifiers
30A 30B in the front ends 26A 26B, and the control signal (X) for the first 48 and
second 60 intermediate frequency switches. The buffers 72 also allow the processor
32 to control the camera 24 to trigger image acquisition, to add information to the
image, and to receive a representation of the acquired image, from the camera 24,
for onward transmission, by a communications interface 74, also on the buffers of
the processor 32 to another location. It is to be understood, in the description of
Figure 2, of Figure 3, and in the following claims, that the invention encompasses
the processor 32 comprising a second processor, whose specified functions include
image acquisition from the camera 24 and/or onward transmission of the image.The communications
interface 74 can be for radio, landline or cable use, dependently upon the permanency
and/or disposition of the site of use of the invention.
[0042] A gain control digital to analogue converter 76 receives a gain control digital signal
from the bus of the controller 32 to control the gain of the second gain control amplifier
54. Finally, non-volatile read only memory (EPROM) and random access memory (NVRAM)
are coupled to the processor 32 to provide the program and operational memory for
the processor 32.
[0043] The action of automatic gain control from the processor 32 is best illustrated by
an example of how the embodiment of Figure 2 can be made to perform. At a minimum
input signal level of -110dBm, the system is "wide open" and maximum gain applied
(around 80dB) between the antenna 14 and the processor. At -40dBm input, all intermediate
frequency (IF) analogue gain control (in 54) is applied to minimise the gain of the
second gain control amplifier 54. At -20dBm input, the low noise amplifier 30A 30B
is bypassed (Odb gain). At -10dBm input, the second gain control amplifier 54 is bypassed
to give an overall system gain of -10dB, which is still within the limit that the
controller 32 can accept, and with acceptable signal to noise ratios at all levels
to ensure linearity of processor 32 operation. By use of multiple gain control strategies,
the system can operate over a very wide range of inputs, in this example, theoretically
100dB (and practically around 90dB). Put simply, this represents a power range of
received signals having a ratio of ten billions to one over which the embodiment will
operate.
[0044] While only two front ends 26A 26B have been shown in this example, it is to be appreciated
that more than two front ends 26A 26B can be switched in the same manner for their
received signals to be examined in turn. It is also to be appreciated that a front
end 26A 26B can be switched between different antennae to scan different target areas
in turn.
[0045] Attention is next drawn to Figure 3, showing a schematic diagram of the functional
parts of a simplified, single band embodiment of the invention. Like numbers denote
like elements, with any slight differences explained.
[0046] A third radio frequency front end 26C, the sole front end in this embodiment, has
its first band pass filter 28C covering the range 800 MHz to 2700 MHz, thereby spanning
the range of mobile telephone coverage, and other styles of service, mentioned in
relation to Figure 2. Apart from the change in frequency range, all is as in the first
and second front ends 26A 26B, with the exception that a simple diode detector 80,
for preference a Schottky diode detector, in view of the high frequencies involved,
acts as a direct demodulator. The receiver, in this instance, is not a super heterodyne
receiver but a wide band "Tuned Radio Frequency" (TRF) receiver. The expense of variable
frequency oscillators 46A 46B 38A 38B, radio frequency mixers 36A 36B, phase locked
loop components 40A 40B 42A 42B and demodulator components 62 64 56 58 is avoided.
The signal strength digital to analogue converter 70A derives its analogue input,
in this instance, directly from the diode detector 80, and only a single signal digital
to analogue converter 68C provides input to the processor 32 bus, after an analogue
processing stage 82 has modified the output from the diode detector 80. The receiver
of Figure 3 needs no alignment and can be accommodated on a single, compact circuit
card.
[0047] The analogue processing stage 82 comprises base band filters, which limit noise,
and can comprise autonomous automatic gain control stages to control the level of
signal presented to the input of the signal analogue to digital converter 68C. The
processor 32 is a digital signal processor and, when the Received signal strength
indication (RSSI) from the signal strength digital to analogue converter 70A exceeds
a predetermined limit, the processor 32 performs a Fast Fourier Transform (FFT) on
the output data stream from the signal analogue to digital converter 68C to establish
the spectrum of the signal arriving at the antenna 14, The processor 32 then compares
the spectrum with different types of spectrum which belong to a set of spectral types
which would cause the camera 24 to trigger. If a match is found, the camera 24 is
triggered. The processor 32, in Figure 2, can operate in the same manner, though it
is to be appreciated that any system of operation for the processor 32 which permits
identification of at least one type, or of several types, of signal , can be applied
in the present invention. For example, it may be sufficient to identify TDMA (Time
Division Multiple Access) transmission slots to establish the use of a GSM style mobile
telephone.
[0048] Attention is now drawn to figure 4, which shows a flow chart of the activity of the
processor 32, applicable to both Figures 2 and 3.
[0049] In a first activity 84, the receiver simply scans the band or bands for signals.
In the case of the Figure 2 embodiment, the controller 32 operates the intermediate
frequency switches 48 60 to look at the signals from each front end 26A 26B in turn.
In the case of the Figure 3 embodiment, the processor 32 can scan the output of the
analogue processor stage 82, or simply wait for activation. A first test 86 has the
processor 32 examine the output from the signal strength analogue to digital converter
70 70A. If a predetermined amplitude limit has not been exceeded, control passes back
to the first activity. If the predetermined limit if received signal strength indication
(RSSI) has been exceeded, control passes to a second activity 88 where the controller
32 examines the base band signal presented to its bus to determine the nature of the
signal being received. In the case of the Figure 2 embodiment, the processor 32 created
the vector sum of the outputs of the phase demodulator 56 and the quadrate demodulator
58 to give an enhanced signal to noise ration, and examines the result. In the case
of the Figure 3 embodiment, the processor 32 examines only the output of the analogue
processing stage 82. A second test 90 then checks to see if a match can be found between
the type of signal being received and any targeted type of signal for which the camera
24 should be activated. If no match is found, control returns to the first activity
84. If a match is found, control passes to a third activity 92 where the processor
32 triggers the camera 24, appends any details to the image, and subsequently transmits
the image to another place, while, for preference, retaining a permanent record of
the image. Control then passes back to the first activity 84.
[0050] During the third activity 92, the nature of the image can take many forms. If the
camera 24 is a speed detection camera, details of the vehicle velocity will automatically
be appended without intervention by the processor 32, thereby showing that the vehicle
was in motion. If the camera 24 is not a speed detection camera, the image can comprise
two or more frames taken at known intervals to demonstrate that the vehicle was in
motion against a fixed background. In the final instance, the image can comprise a
series of frames, in the form of a video image. When linked to a video camera in an
enforcement vehicle, or on a video surveillance camera, the triggering of the camera
can take the form of marking frames of video footage, if the camera is running, to
show that mobile communications are in progress, together with starting the camera
if it happens not to be running at the time.
[0051] Attention is next drawn to Figure 5, showing one way in which a portable version
of the invention can be implemented.
[0052] A housing 94, comprising a pistol grip 96 for an operator to hold and aim the device
and having a trigger 98 for the operator to activate the device, serves as a mounting
for a directional antenna 14 and a camera 24, looking past but in the same direction
as the directional antenna 14. The housing also incorporates one or other of the embodiments
of Figure 2 or Figure 3. In use, the operator simply points the directional antenna
14 into the path of an oncoming vehicle and, if mobile communications activity is
detected, the camera 24 is activated. The image can then be sent to another place
via a radio link antenna 100.
[0053] For the purpose of clarity and completeness, the items indicated AL in Figure 2 and
3 are amplitude limiters, whose function is solely to protect against excessive signals
or transients damaging the receiver (s).
[0054] The invention is further clarified by the following claims.
1. An apparatus for providing evidence of use of mobile communications in a vehicle,
characterised in that there is provided: a monitor (14) for monitoring emission of radio signals from the
vehicle and operative to provide output indicative thereof; a controller (26,32),
coupled to receive said output from said monitor and operative to determine whether
or not emitted radio signals, from the vehicle, have characteristics indicative of
at least one type, from a predetermined set of types, of mobile communications activity
is in progress in the vehicle; and a camera, (24) operative to acquire an image of
the vehicle, and coupled to be triggered by said controller (32) in the event that
said controller determines that said at least one type of mobile communications activity
is in progress in the vehicle.
2. An apparatus, according to claim 1, wherein said monitor (14) comprises a directional
antenna (14) to be aimed at the vehicle, and a radio receiver (26,32,52), operative
to receive signals from said antenna and to demodulate and measure the strength of
signals from said antenna.
3. An apparatus, according to claim 2, wherein said controller (32) is operative to respond
to the indication of measured strength of the signal from said antenna (14) to determine,
in a first stage (84,86), by a first criterion, if a predetermined signal strength
has been exceeded (86); and, if said predetermined signal strength has been exceeded,
is operative, in a second stage (88), to analyse the demodulated signal to determine
the nature of the signal and to determine, by a second criterion, if the signal belongs
to said at least one type of said predetermined set of types of mobile communications
activity , said controller (32) triggering said camera (24) if said first and second
criteria are fulfilled.
4. An apparatus, according to claim 2 or claim 3 wherein said receiver (26,32,52) comprises
plural automatic gain control amplifier stages (30) for accommodating a wide range
of signal strengths from said antenna (14).
5. An apparatus, according to claim 4, wherein said controller (32,72) is operative to
control the gain of at least one of said stages.
6. An apparatus, according to claim 2, 3 or 4 wherein said receiver is band limited (26c)
to receive only that band or those bands of radio signals wherein said predetermined
set of types of mobile communications activity are expected to occur.
7. An apparatus, according to claim 1, 2, 3, 4, 5 or 6, wherein said controller (32),
when triggering said camera (24), is operative (72,74) to append details to the acquired
image, indicative of the type and time of detected radio communications activity.
8. An apparatus, according to claim 1, 2, 3, 4, 5, 6, or 7 wherein said apparatus is
portable (94) and wherein said antenna (14) can be pointed into the path of an oncoming
vehicle.
9. An apparatus, according to claim 2, 3, 4, 5, 6, 7 or 8 wherein said antenna (14) is
adapted for suspension above a road surface.
10. An apparatus, according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 wherein said camera (24)
provides a secondary function as a roadway speed detection camera.
11. An apparatus, according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wherein said predetermined
set of types of radio communications activity includes the use of one or more types
of mobile telephone.
12. An apparatus, according to claim 11, wherein said one or more types of mobile telephone
include one or more of those operating with TDMA, CDMA, GSM, DCS, PCS, NADC, AMPS,
TACS, CDPD, DECT or ISM..
13. An apparatus, according to claim 6, or according to claim 7, 8, 9, 10, 11 or 12 when
dependent upon claim 6, wherein said predetermined band or set of bands whereon said
predetermined set of types of radio communications activity are expected to occur
comprises a plurality of bands, and wherein said receiver is operative to switch (48,60)
from one to another of said plurality of bands.
14. An apparatus, according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13 wherein
said controller (32) is operative to transmit the acquired image to a another location.
15. An method for providing evidence of use of mobile communications in a vehicle, characterised
by the steps of: monitoring emission of radio signals from the vehicle (14,84) and
providing output indicative thereof; examining (26,32,52,84,86) said output, indicative
of radio emission from the vehicle and determining whether or not emitted radio signals,
from the vehicle, have characteristics indicative of at least one type, from a predetermined
set of types, of mobile communications activity being in progress in the vehicle;
and acquiring an image (24,92) of the vehicle in the event that said at least one
type of mobile communications activity is in progress in the vehicle.
16. An method, according to claim 15, wherein said step (16) of monitoring the vehicle
includes the use a directional antenna (14) to be aimed at the vehicle, and the use
of a radio receiver (26,32,52) to receive signals from said antenna (14) and to demodulate
and to measure the strength of signals from said antenna
17. An method, according to claim 16, wherein said step of examining said output indicative
of radio emissions includes the steps of: examining an indication of measured strength
of the signal from said antenna and determining, in a first stage (84,86), by a first
criterion, if a predetermined signal strength has been exceeded; if said predetermined
signal strength has been exceeded, in a second stage (88,90), analysing the demodulated
signal to determine the nature of the signal and to determine, by a second criterion,
if the signal belongs to said at least one type of said predetermined set of types
of mobile communications activity; and acquiring (92,24) said image if said first
and second criteria are fulfilled.
18. A method, according to claim 16 or claim 17, for use where said receiver (26,32,52)
comprises plural automatic gain control amplifier stages (30) for accommodating a
wide range of signal strengths from said antenna (14).
19. A method, according to claim 18, wherein said step of examining said outputs includes
employing an analysis of said outputs to control the gain of at least one of said
stages.
20. A method, according to any one of claims 16, 17 or 19, for use where said receiver
is band limited (26c) to receive only that band or those bands of radio signals wherein
said predetermined set of types of mobile communications activity are expected to
occur.
21. A method, according to any one of claims 15 to 20, including the step (72,74) of appending
details to the acquired image, indicative of the type and time of detected radio communications
activity.
22. A method, according to any one of claims 15 to 21, for use in a portable apparatus
(Figure 5) and wherein said antenna (14) can be pointed into the path of an oncoming
vehicle.
23. A method, according to any one of claim 15 to 22, including the step of suspending
said antenna above a road surface.
24. A method, according to any one of claims 15 to 23, wherein said step of acquiring
said image includes use of a camera (24), where said camera provides a secondary function
as a roadway speed detection camera.
25. A method, according to any one of claims 15 to 24, wherein said predetermined set
of types of radio communications activity includes the signals emitted by of one or
more types of mobile telephone.
26. A method, according to claim 25, wherein said one or more types of mobile telephone
include one or more of those operating with : TDMA, CDMA, GSM, DCS, PCS, NADC, AMPS,
TACS, CDPD, DECT or ISM..
27. A method, according to claim 20, or any one of claims 21 to 26 when dependent upon
claim 20, wherein said predetermined band or set of bands (25A, 26B, 26C) whereon
said predetermined set of types of radio communications activity are expected to occur
comprises a plurality of bands, and wherein said step of monitoring emission of radio
signals includes causing said receiver (48, 60) to switch from one to another of said
plurality of bands.
28. A method, according to any one of claims 15 to 27, including the step (72,74) of transmitting
the acquired image to a another location.