Abstract: A phase locked loop (10) comprising: a tuneable oscillator (12); a mixer-based phase sensitive detector (18) to receive input signals from the tuneable oscillator (12) and a reference signal (20); a cycle slip detector (26) to receive input signals from the tuneable oscillator (12) and the reference signal (20), the cycle slip detector (26) being configured to generate an output signal when two consecutive pulses are present in one of its input signals without an intervening pulse in the other of its input signals; coarse tune signal means (32, 34) to receive the output signal generated by the cycle slip detector; and adding means (24) for adding a signal output by the coarse signal means (32, 34) to a signal output by the phase sensitive detector (18) to control the frequency of the tuneable oscillator (12).

Abstract: A phase locked loop (10) comprising: a tuneable oscillator (12); a mixer-based phase sensitive detector (18) to receive input signals from the tuneable oscillator (12) and a reference signal (20); a cycle slip detector (26) to receive input signals from the tuneable oscillator (12) and the reference signal (20), the cycle slip detector (26) being configured to generate an output signal when two consecutive pulses are present in one of its input signals without an intervening pulse in the other of its input signals; coarse tune signal means (32, 34) to receive the output signal generated by the cycle slip detector; and adding means (24) for adding a signal output by the coarse signal means (32, 34) to a signal output by the phase sensitive detector (18) to control the frequency of the tuneable oscillator (12).

Abstract: A spectrum analyser that includes means (8) for converting, at each of a series of frequency settings, a received radio frequency signal into an intermediate frequency signal, each intermediate frequency signal being derivable from more than one nominal received radio frequency signal. The spectrum analyser carries out a frequency analysis (14) of each intermediate frequency signal to produce a power spectrum thereof and constructs a composite received radio frequency signal power spectrum corresponding to each intermediate frequency signal power spectrum. The composite radio frequency signal power spectrums are then operated on by the spectrum analyser to provide the actual power spectrum of the received radio frequency signal.