Abstract :
A `long loop¿ v.h.f. phase-locked a.m. receiver with synchronous detector is described. The effect of the narrow-band Chebyshev i.f. filter on receiver lock-in range, hold-in range and capture time is investigated as a function of carrier level, ¿60 to ¿120 dBV, for a range of low-pass filter time-constants. The transient response of the Chebyshev filter and instantaneous limiting in the i.f. strip are shown to play a crucial role in determining the time which the receiver takes to lock onto the carrier. The receiver is not significantly more complex or expensive than sets currently in use and has the advantage that it may also be used to demodulate double-sideband diminished carrier (d.s.b.d.c.) signals.
