Digital demodulation system having independently operating

Abstract

In a digital radio transmission in which first- and second-channel radio frequency digital signals are transmitted respectively on othogonally polarized radiowaves and first and second IF signals are derived respectively from the first- and second-channel RF signals. The second IF signal is proportioned in response to a control signal and subtractively combined with the first IF signal. A main digital demodulator provides demodulation on the combined IF signals to generate a main (N+1)-bit output and derives an N-bit data signal from N higher significant bits of the (N+1)-bit output and an error component from the LSB of the main (N+1)-bit output. An auxiliary digital demodulator provides demodulation of the second IF signal to generate an auxiliary (N+1)-bit output and derives a data component of the second channel from the MSB of the auxiliary (N+1)-bit output. The derived error and data components are supplied to a correlator to generate the control signal.