Spectrum analyzer
AssigneeTakeda Riken Kogyo Kabushikikaisha
InventorHitoshi Ashida
Life of this patent
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Abstract
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.
Claims22
A spectrum analyzer for analyzing the amplitude and phase characteristics of a device under test as a function of frequency, said device being connected between a measuring signal output terminal and an input terminal of the spectrum analyzer, said analyzer comprising:
- means for repeatedly generating a sweep control signal,
- a sweep oscillator controlled by the sweep control signal to repeat a continuous sweeping of its oscillation frequency to repeatedly output a frequency swept signal,
- a first frequency converter connected to the output of the sweep oscillator, for frequency mixing said frequency swept signal and an input signal from said device under test applied to said input terminal, and to output a corresponding signal;
- a first detector connected via a first path to the output of the first frequency converter for detecting a signal corresponding to the amplitude of the output of the first frequency converter;
- a first oscillator outputting an oscillating signal at a frequency equal to the frequency of a signal in said first path;
- a second frequency converter for frequency mixing a signal corresponding to the output from said first oscillator and said frequency swept signal, and for producing a measuring signal to be supplied to said measuring signal output terminal, said second signal having the same frequency as said output from said first frequency converter;
- and
- a second detector for detecting the phase difference between two inputs thereto, these inputs being a signal that is taken-out from said first path and corresponds to said output of said first frequency converter and a reference signal of the same frequency as said taken-out signal, said reference signal being derived from the output of said first oscillator.
Dependencies are inferred from the claim text.