Radio receiver circuit displaying preset transmit frequencies - has programmable fixed value memory for transmit frequencies, interrogated by clock pulse generator and counter

摘要

The circuit containing a radio receiver has manual oscillator tuning. A programmable fixed value memory (10) stores the preset transmit frequencies, and is interrogated by a clock pulse generator (11) and a counter (12) in such a manner that all stored transmit frequencies appear sequentially during a period of the clock pulse generator at the output (10A) of the memory in a cyclic manner. A frequency counter (17) measures the oscillator (16) generated frequency which also corresponds to the received transmit frequency. A comparator (13) treats the stored and received frequencies and generates a signal, on coincidence, triggering the optical or acoustic display (19). Between the frequency counter and the comparator is pref. incorporated a memory (18), set at the end of each measuring period by the frequency counter generated pulse. It also stores, during the measuring period of the frequency counter, the received transmit frequency.