A New Digital Coherent Demodulator

A coherent demodulator is described which is particularly well suited to digital implementation. Its important features are that no low-pass filter is required to eliminate double-frequency terms and that the passband signal need be sampled at only twice the highest frequency of the baseband signal, rather than at twice the highest frequency of the passband signal. A demodulator of this type will be useful in those systems that do not require passband digital signal processing for other purposes.