Muting signal recovery and processing arrangement for RDS car radio

摘要

The arrangement includes a bandpass filter (1), logarithmic operator (2), diode (3), and low pass filter (4). The input signal (MPX) is passed through these to produce a signal (S2). This signal is then operated on separately by an adder (5), which increases the signal level (pref. by 0.6V), and by two independent time-constant delay circuits (6,7). The outputs of each of these circuits are fed to respective inputs of a level comparator (8) with the adder output being fed to the reference input (A). The comparator output (S6), which is essentially a negative pulse of short time span (pref. about 8 ms), is then fed to a radio muting circuit.