Abstract: In order to automatically set a predetermined frequency component of a voltage-controlled oscillator of a spectrum analyzer which is swept by a sweep voltage to a prescribed point of a frequency coordinate on a display device, the oscillator is connected into a phase control loop of a frequency synthesizer as its oscillator. This connection is by way of one switch position of a transfer switch, in which the tuning voltage supplied by a phase comparator of the control loop is supplied to a storage element and, in the other switch position, the phase control loop is opened and the output of the network connected to the storage element is connected to the control input of the oscillator. The network is controllable by way of a control voltage such that the stored tuning voltage may be supplied to the control input of the oscillator as a reference voltage for the sweep voltage.

Abstract: A device for inspecting an individual high frequency signal selected according to frequency from a broad frequency band comprises a voltage controlled oscillator which can be controlled with respect to frequency by a periodic sweep voltage, in particular a linear sawtooth voltage, in such a manner that all signals occurring in the frequency band can be displayed as a spectrum in the picture screen of a cathode ray tube. The device further comprises a frequency marker generator which has a device for generating a frequency mark voltage and a voltage comparator for, given sweep operation and equality between an adjusted frequency marker voltage and a momentary sweep voltage, generating a frequency mark on the picture screen which is adjustable to identify a corresponding fixed frequency after termination of the sweep operation for inspecting an individual frequency-selected signal.