Abstract: A measuring unit converts a measuring signal into an intermediate frequency band of a predetermined bandwidth and detects the intermediate frequency band while a reception frequency is set variable by variably controlling a local oscillation frequency of a local oscillator. A waveform memory stores the magnitude of a detection signal output from the measuring unit in correspondence with the frequency. An analyzing unit analyzes a frequency component included in a signal to be measured, on the basis of a storage value of the waveform memory. An analysis target frequency data setting unit sets frequency data of a desired analysis target frequency or interval frequency data thereof.

Abstract: A spectrum analyzer comprising various components. In the analyzer, a high-frequency signal processing circuit frequency-converts an object signal including waves recurring for a short period of time, into an intermediate-frequency signal, by using a local oscillation signal swept continuously over a desired range of frequencies, and thereby outputs a frequency spectrum of the object signal. A demodulator demodulates the frequency spectrum output by the high-frequency signal processing circuit. A selection signal supplying section supplies a selection signal for selecting that portion of the spectrum output by the demodulator, which lies waves to be analyzed. A control section outputs said portion of the spectrum output by the demodulator, in accordance with the selection signal output from the selection signal supplying section. A display displays the frequency spectrum output by the control section.

Abstract: A frequency conversion section sweeps an object signal within a desired measurement frequency range, thereby frequency-converting the object signal. A peak detector detects a peak of an output from the frequency converting section. A measurement detector measures and detects the output from the frequency conversion section simultaneously with the peak detection by the peak detector. The measurement detector has an output characteristic lower than an output characteristic of the peak detector. A display displays an output from the peak detector and an output from the measurement detector on a single display screen, in synchronism with the sweeping by the frequency conversion section, with these outputs of the peak detector and the measurement detector being plotted along an axis representative of frequencies. In another mode of the invention, an alarm device indicates the fact that an output from the peak detector has exceeded a predetermined allowable limit level.