Signal-to-noise ratio measurement of intermittent signals

摘要

The signal-to-noise ratio of intermittent reception by a radio receiver from a push-to-talk transmitter is measured by comparing AGC voltage levels derived from a signal period with levels derived from the prior no-signal period containing noise only. The AGC voltages are applied to a pair of integrators having corresponding time constants and therefore normally having equal outputs. When a valid signal period is recognized, the output of one integrator is held to represent an integration of voltage levels during the prior no-signal period. The integrated signal thus held is thereafter compared with the running output of the other.