FREQUENCY DISCRIMINATOR AND HETERODYNE RECEIVER PROVIDED WITH THE FREQUENCY DISCRIMINATOR FOR COHERENT LIGHTWAVE COMMUNICATIONS

摘要

In a frequency discriminator in which it isadapted such that a signal to be subjected to frequencydiscrimination is divided into two signals and mixedtogether after one of the divided signals has been givena delay time, the frequency discriminator disclosed isadditionally provided with a filter, of which cutofffrequency is set up according to the delay time,disposed in the front stage and, thereby, bothimprovement of accuracy in frequency identification andexpansion of the capture range can be attained.