(57) A control system wherein a central control station (4) is connected, by means of
a bipolar cable (9), to at least one peripheral station (7), coupled with at least
one railroad signal (11), provided with three light sources (13r, 13y, 13g), respectively,
red, yellow and green, obtained from incandescence lamps. Each incandescence lamp
(13r, 13y, 13g) is capable of being supplied by a respective band-pass filter (31,
32, 33), receiving, at its input, the signal sent from cable (9). Central station
(4) is fitted with a signal generator (18), capable of supplying on cable (9) a periodic
alternating signal, whose frequency (Fl, F2, F3) can be chosen among three different
frequencies (Fl, F2, F3), each whereof corresponds to the central frequency of a respective
band-pass filter (31, 32, 33) of peripheral station (7).
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