Importance

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Abstract

An amplitude modulated (AM) radio receiver uses a digital signal processor, responsive to in-phase (I) and quadrature-phase (Q) component signals, to compensate for carrier energy removed by a capacitive coupling circuit. A quadrature mixer converts the received AM signal to the I and Q component signals representative of the AM signal, and a signal filter passes a desired frequency segment of the I and Q component signals. A capacitive coupling circuit couples the I and Q component signals to provide representative I and Q signals with no DC bias to the input of an analog-to-digital converter. The analog-to-digital converter converts the representative unbiased I and Q signals to digital I and Q signals for processing by the digital signal processor. The digital signal processor then: (a) determines the absolute values of the I and Q digital signals; (b) compares the absolute value of the I digital signal to the absolute value of the Q digital signal and determines which value is greater; and in response to the outcome of the comparison, provides a digital output word as function of one of the following terms I.times.(1+((2).sup.1/2 -1) .vertline.Q/I.vertline.), Q.times.(1+((2).sup.1/2 -1) .vertline.I/Q.vertline.). A digital-analog converter then converts the digital output word to an analog signal representing the AM demodulated signal.

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First Claim