Dual conversion GPS frequency converter and frequency plan for same
First Claim
1. A GPS frequency converter comprising:
- input means for receiving an input signal having an RF frequency and modulated by a code at a preset code rate, said RF frequency being greater than 1000 MHz;
means for producing a first LO signal having a LO frequency, said LO frequency being greater than said RF frequency by a non-zero multiple of a sampling rate, at which said input signal is sampled, plus or minus a non-zero multiple of said code rate; and
first mixer means for receiving said input and first LO signals and for outputting a first intermediate signal having a first IF frequency equaling a difference between said LO and RF frequencies, said difference being less than 30 MHz.
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Abstract
A GPS frequency converter is provided, according to the present invention, to down-convert the frequency of an incoming GPS signal. The converter includes first and second mixers, the former of which receives the incoming RF signal and a signal from a local oscillator. The local oscillator signal is increased by a factor of 98 and then subtracted from the incoming RF signal to produce a first intermediate frequency signal (IF). The first IF signal is then passed to the second mixer which subtracts the frequency of the local oscillator therefrom to produce a second intermediate frequency signal (IF). The second IF signal is passed through a limiter and output as the frequency converted signal.
68 Citations
19 Claims
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1. A GPS frequency converter comprising:
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input means for receiving an input signal having an RF frequency and modulated by a code at a preset code rate, said RF frequency being greater than 1000 MHz; means for producing a first LO signal having a LO frequency, said LO frequency being greater than said RF frequency by a non-zero multiple of a sampling rate, at which said input signal is sampled, plus or minus a non-zero multiple of said code rate; and first mixer means for receiving said input and first LO signals and for outputting a first intermediate signal having a first IF frequency equaling a difference between said LO and RF frequencies, said difference being less than 30 MHz. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A GPS frequency converter comprising:
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input means for receiving an input signal, said input signal being an RF signal having an RF frequency and modulated by a C/A code having a chipping rate of fO ; means for producing a first LO signal having a first LO frequency equaling 98 times a sampling reference frequency of 16*fO ; and first mixing means for receiving said first LO signal and said RF signal and for producing a first IF signal having a IF frequency substantially equal to 28*fO. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification