A system is provided wherein a primary radio signal and a redundant radio signal
are transmitted from a transmitter subsystem and received by a receiver subsystem.
The output of an audio source is coupled to a modulator for modulating a radio
frequency signal for coupling to a transmit antenna. A second output of audio source
is coupled to a delay circuit, for adding a predetermined time delay thereto. The
delayed audio source signal is coupled to a modulator for modulating a second radio
frequency signal that is also coupled to the transmit antenna. The receiver subsystem
receives both the primary radio signal and the delayed redundant radio signal and
couples each to a respective demodulator. At least one demodulator includes a circuit
for determining the degradation in the primary radio signal and provides a quality
measurement output signal to a blend control circuit.
