Patent ID: 7877073
Filing Date: 2011-01-25
Classification: H04B

Abstract:
1. A superheterodyne radio receiver comprising: at least one local oscillator for generating a local oscillator signal over a range of frequencies; a mixer stage in which a RF signal received at a selected frequency is mixed with a local oscillator signal at a corresponding frequency to downconvert the received RF signal to an intermediate frequency signal containing substantially identical intelligence as the received RF signal, said mixer stage employing low-side injection if the selected RF signal falls generally within a lower half of the passband, and high-side injection if the selected RF signal falls generally within an upper half of the passband; and image rejection circuitry employing a passband with a used portion that is about four times the fixed intermediate frequency, said used portion passing a desired signal received on any of multiple channels within a broadcast band, but rejecting an image signal at an unselected frequency that is associated with the desired signal due to sideband ambiguity inherent in the signal mixing process, which image signal would otherwise be converted to an interfering signal at the same intermediate frequency.