Patent ID: 8036311
Filing Date: 2011-10-11
Classification: H03J

Abstract:
1. An apparatus for digitally compensating received radio frequency signals, comprising: an oscillator; a GPS receiver; a downconverter for receiving the received radio frequency signals the downconverter being driven by the oscillator and having a mixer; a frequency monitor adapted to measure the frequency of the oscillator; an analog-to-digital converter driven by the oscillator; a digital receiver driven by the oscillator, the digital receiver having a numerically controlled oscillator and a mixer configured to mix the received radio frequency signals with a radio channel having a center frequency, the center frequency being adjustable under control of the numerically controlled oscillator; a digital demodulator; and a computer adapted to receive the frequency measurement of the oscillator from the frequency monitor, to determine the presence of an error with the oscillator based on at least the frequency measurement of the oscillator from the frequency monitor and GPS based data from the GPS receiver, and to calculate a numerically controlled oscillator setting configured to compensate for the error with the oscillator; wherein the digital receiver is adapted to receive the numerically controlled oscillator setting from the computer to compensate for the error with the oscillator by adjusting the center frequency of the radio channel of the mixer and mixing the received radio frequency signals with the adjusted radio channel, and to cause the digital receiver to transmit a signal of a desired frequency to the digital demodulator.