Abstract: An FM signal generator generates an FM signal obtained by frequency-modulating a reference frequency signal with a modulating frequency signal. A first mixer mixes the FM signal and an input signal having a predetermined carrier frequency and outputs a pair of frequency signals having sum and difference frequencies thereof. A first signal extracting unit extracts one of the pair of frequency signals as an intermediate frequency signal. A delay circuit delays the extracted intermediate frequency signal by a predetermined time. A second mixer mixes the delayed intermediate frequency signal and the FM signal and outputs a pair of frequency signals having sum and difference frequencies. A second signal extracting unit extracts the frequency signal of the pair of frequency signals which corresponds to the carrier frequency component as a phase-modulated signal. The modulation degree and modulation frequency in phase modulation for the phase-modulated signal can be set in wide ranges.

Abstract: A target signal input to a mixer circuit of a frequency converter is frequency-converted to have a low frequency by a signal obtained by frequency-multiplying an output signal from the voltage-controlled crystal oscillator by M. The frequency-converted output is compared with the output signal from the voltage-controlled crystal oscillator by a phase/frequency comparator. A loop filter receives an error signal based on the phase/frequency comparison and performs loop control to lock the phase of the output signal from the voltage-controlled crystal oscillator to the phase of the output signal from the frequency converter. The jitter component of the target signal exhibiting phase variations at a frequency higher than a loop band contained in the error signal is output from a jitter detection filter before the loop filter via a branching circuit. Even if the target signal having a high frequency undergoes a great frequency change, stable, accurate jitter measurements can be performed following the change.

Abstract: A frequency marker display system for displaying markers on a display device such as a cathode ray tube includes means for generating gating pulses whereby only a desired pair of frequency markers, appearing on each side of a center frequency marker, are displayed. Selection of the side frequency markers is accomplished by an operator-actuated switch which produces a DC signal, this DC signal being compared with the level of a sweep repetition rate controlling signal, and said gating pulses are produced when the levels of said DC signal and that of said sweep repetition rate controlling signal coincide.