Robert Boschgmbh

Blaupunkt-werke Gmbh

Dieter Heiss

Uwe Matzold

To decode control signals from a mixture of signals including audio signals, such as music, voice or speech, in which the control signals are within the audio range, for example 2,350 Hz, on which a low-frequency signal, for example in the 100-200 Hz range is modulated, the control signal in the form of a control tone is filtered and demodulated by band pass filters (1,3), demodulators and rectifiers (2,4), and then applied to a timing circuit (5) which provides an output signal if and only if the demodulated control tone is continuously applied during the timing interval thereof. Suitable timing intervals are about 1 second, to provide an output signal which can switch a flipflop (7) on, for example to command radiation of a particular type of recognition signal by the transmitter (13), the setting of the flipflop (FF) (7) being fed back to the timing circuit to change the timing interval thereof to a lesser amount, for example 1/2 seconds, to provide for a shorter signal to cause resetting of the FF (7). A second timing circuit (9) is provided to turn OFF the FF (7) in case it is overlooked to generate a 0.5 turn OFF signal and apply it to the first timing circuit (5).

Remote control system, particularly for remote radio transmitter control

To permit mass-production of coders selectively usable in various types of transmitter installations, and regardless of whether designed for stereophonic or monophonic transmission, in which a subcarrier of non-audible frequency (57 kHz) is radiated, amplitude modulated by separate recognition signals characterizing intelligence information (AR, or announcement recognition) and a specific transmitter (region or radio station recognition, RR), a memory element (36) such as a PROM is provided, connected to a selector switch, the memory element having stored therein data representative of

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Hildesheim, Germany

Dieter Heiss