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US 3,932,814 AGranted
Heterodyne receiver system
AssigneeTakeda Riken Kogyo Kabushikikaisha
InventorShoji Niki
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AssigneeTakeda Riken Kogyo Kabushikikaisha
InventorShoji Niki
Estimating the term…
An input signal and a local oscillator signal are supplied to a harmonic mixer. The local oscillator signal is swept over a frequency range. The output from the harmonic mixer is supplied to an intermediate frequency filter having a preselected frequency response, which provides an output signal when the difference formed by subtracting one of the input signal frequency and one harmonic frequency of the local oscillator signal from the other is equal to the intermediate frequency or when the difference formed by subtracting the other frequency from said one frequency is equal to the intermediate frequency as the local oscillator frequency is swept. By choosing a time interval between the times when the pair of intermediate frequency output signals are obtained, the order of that harmonic of the local oscillator signal with which the intermediate frequency output signal is obtained is determined depending on the frequency of the input signal. Thus, with a chosen time interval, when the frequency sweep of the local oscillator signal is interrupted with the later occurring one of the pair of the intermediate frequency output signals, the frequency of the local oscillator permits, together with the order of selected harmonic which corresponds to the chosen time interval and the direction of the frequency sweep, the frequency of the input signal to be determined. By using a definite time interval between the pair of intermediate frequency signals obtained and adjusting the rate of the frequency sweep, the order of the harmonic which is effective to obtain the intermediate frequency signals can be varied.
A heterodyne receiver system for determining the frequency of an input signal, comprising means for receiving an input signal the frequency of which is to be determined, a frequency swept local oscillator for generating a local oscillator signal and harmonics thereof, a frequency converter responsive to said local oscillator signal and to said input signal and operative to provide a frequency mixing of the input signal frequency with the local oscillator signal frequency and its harmonic frequency, an intermediate frequency filter coupled to said converter for passing those outputs of the frequency converter which are of a predetermined intermediate frequency, an intermediate frequency detector coupled to said filter for detecting the occurrence of signals at said intermediate frequency, said filter producing a pair of time spaced signals at said intermediate frequency at different times in response to a same input signal and for a given order of harmonics of the local oscillator signal, means for extracting one signal of said pair of signals, which occurs at a given time interval after a first occurring one of said intermediate frequency signals thereby to elect said one of said pair of intermediate frequency signals which occurs later in time, and means response to the occurrence of said elected signal within said given time interval for determining the frequency of said input signal.
Dependencies are inferred from the claim text.