Fast and sensitive simultaneous measurement of many signals by means of multi-channel coherent receiver is described. All received signals are of different modulating frequencies, synchronous to one reference frequency. The ratio of all modulating signals periods to reference period is an integer. Two practical applications of multi-channel coherent receiver are given: multipoint measurement of electromagnetic field distribution with MST method and two-channel EPR spectrometer

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The use of a new signal, a multi-frequency coherent signal is presented for measurement of inter-modulation components caused by nonlinearity of transmission channel. This signal allows the use of digital coherent demodulation for measurement of inter-modulation components. It makes possible measurement of very weak signals, undetectable by noncoherent measurement.

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