Patent GB-1474427-A (GB)
Title: Tunable radio receiving set
IPC: G08G1/09
Filed: 1974-08-02
Abstract: 1474427 Radio signalling and receiver tuning and muting INTERNATIONAL STANDARD ELECTRIC CORP 2 Aug 1974 [2 Aug 1973] 34151/74 Headings H4L and H3Q In a radio for receiving identification waves simultaneously with special information, such as road traffic information, and together with normal radio programme material the identification waves are extracted from a pilot wave by a demodulator 11, a frequency selective identification wave switch 12 has individual selectorswitches 15-17 for selection of the identification waves, an arrangement 20-22 is responsive to the operation of an information selector switch 18, for selecting a periodically transmitted special information wave, to inhibit drive of a tuning device 8 and to inhibit further operation of the frequency selective identification wave switch 15-17 and a muting device 19 is disabled on reception of the information identification to permit selective reception of the special information wave. Pressing switch 13 provides normal FM reception, and cancels the muting effect of circuit 19. If a pilot wave occurs it is indicated by a lamp or LED 26. Selector switch 14 selects all transmitters modulated with a 57 kHz pilot whereas by selector switches 15-17 the transmitters are selected according to their continuous identification waves by selecting the resonant frequency of the selective identification wave switch 12 to the frequency of the selected continuous identification wave. Only one of the push button switches 13-17 can be actuated at a time and when one is pressed the others are released. When one of the switches 14-17 is actuated, only when a transmitter with the selected identification is received whilst tuning the receiver, is the muting effect of the muting circuit 19 cancelled. A selector switch 18 is coupled to a locking device 20 which locks the settings of the selector switches 13 to 17 and operates a disconnecting device 21 for a clutch 22 to disconnect a tuning drive knob 9 from a tuning element 8. The operation of the switch 18 to be locked position is indicated by a lamp or LED 24. When the switch 13 is selected for normal FM reception a locking device prevents the information selector switch 18 from being actuated. In a modified embodiment (Fig. 2, not shown) a pawl 35 is forced between the teeth of a toothed disc 29 attached to the tuning drive knob 9 when the selector switch 18 is actuated. In a further embodiment (Fig. 3, not shown) the tuning device 8 includes a digital counter (8a), driven by a pulse generator (9a) until stopped by a stop circuit (9b) of a digital automatic station search arrangement on output of a received signal from the IF demodulator 5 when selector switch 13 is activated or from the pilot selector switch 14 or from the frequency selective identification wave switch 12 as selected by switches 15-17. During automatic station search the stop circuit (9b) cuts out the a.f., stage 6 over line 36. When one of the selector switches 14-17 is operated a connection via (39, 40 and 18e) ensures that the a.f. stage 6 transmits information to the output only if an information identification wave is present.