Abstract: A waveform measuring apparatus having a dummy readout circuit which applies first read signals of a same period as sampling signals to a read clock terminal of a FIFO memory during an interval between a first moment that a trigger enable signal is outputted from a prepoint counter when digital samples have been stored in the FIFO memory up to a predetermined number (a prepoint value) and a second moment that a trigger signal is generated by a trigger signal generating circuit. Concurrent reading from and writing to the FIFO memory is thereby permitted with a difference between the write pointer value and the read pointer value kept equal to the prepoint value. When a trigger signal is generated, digital data are written into the FIFO memory until the write pointer value catches up with the read pointer value and digital data are read from the FIFO memory by second read signals applied to it by a control unit. A display unit displays the waveform of the measured signal.

Abstract: A measurement unit U100 measures an input signal to be measured by sweeping frequencies in a measurement range having a predetermined frequency band so as to obtain waveform data to be developed on the frequency axis such as spectrum data in, e.g., a spectrum analyzer. The waveform data obtained by the measurement of the measurement unit U100 is displayed by a display device 500 via a display data processor U20 included in a control unit U200 to be described later to be developed on the frequency axis of the display device, i.e., in correspondence with the measurement frequencies.

Abstract: A measurement unit U100 measures an input signal to be measured by sweeping frequencies in a measurement range having a predetermined frequency band so as to obtain waveform data to be developed on the frequency axis such as spectrum data in, e.g., a spectrum analyzer. The waveform data obtained by the measurement of the measurement unit U100 is displayed by a display device 500 via a display data processor U20 included in a control unit U200 to be described later to be developed on the frequency axis of the display device, i.e., in correspondence with the measurement frequencies.

Abstract: A frequency converter receives a signal to be measured and a local oscillation signal supplied from a local oscillator and ouputs an intermediate frequency signal. A phase detector detects a phase of the intermediate frequency signal. An A/D converter outputs a digital value corresponding to a phase detection output. A memory stores a plurality of aperture values. Each of the aperture values is read out with a predetermined frequency band which is incremented at a predetermined step. A first controller causes the local oscillator to oscillate signals having first and second frequencies separated from each other by the aperture value in the vicinity of a desired measurement frequency. An arithmetic unit calculates a group delay time of the signal to be measured in accordance with the two digital values and the aperture value corresponding to the respective phase detection outputs when the local oscillator oscillates the signals having the first and second frequencies.