Importance

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Abstract

A variable frequency RF passband filter is calibrated to maximize the sensitivity of a radio receiver using reference frequencies applied based on the clock operation of a digital processor within the receiver. The reference frequency passing through the variable passband filter is mixed to the intermediate frequency of the receiver and its level is detected. A frequency counter verifies that a measureable reference frequency signal has in fact been mixed to the intermediate frequency in order to avoid errors. The correct control voltage signal for the variable passband filter corresponding to each receiver frequency can thus be conveniently and inexpensively determined and stored for use during normal operation of the receiver.

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First Claim