Takeda Riken Kogyo Kabushiki Kaisha

Hitoshi Ashida

In a spectrum analyzer, an intermediate-frequency oscillator and the outputs from a sweep oscillator are frequency mixed to obtain a measuring signal, which is provided to a device under test. The intermediate-frequency signal and the output from the intermediate-frequency oscillator are supplied to a phase detector to detect a phase difference between them. A signal representing the detected phase difference and the output from a detector are selectively applied by a switch to a display.

Spectrum analyzer

A digital frequency measuring device in which pulses of an input signal are counted for a certain period of time under the control of a gate signal and the count value is displayed in a digital form. A fraction detector circuit is provided for measuring the time interval or difference .DELTA.T.sub.1 between the leading edge of the gate signal and an input pulse arriving after it, the time interval or difference .DELTA.T.sub.2 between the trailing edge of the gate signal and an input pulse arriving after it and the unit period T of the input pulse signal, and performing an operation corresponding to (.DELTA.T.sub.1 - .DELTA.T.sub.2 /T. The result of operation is converted into the corresponding digital value, which is displayed as a fraction value of the abovesaid count value.

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Gyoda, Japan

Hitoshi Ashida