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Dual down conversion GPS receiver with single local oscillator

  • US 5,108,334 A
  • Filed: 06/01/1989
  • Issued: 04/28/1992
  • Est. Priority Date: 06/01/1989
  • Status: Expired due to Fees
First Claim
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1. A receiver for receiving a 1540 f0 frequency GPS satellite signal, said receiver comprising in combination:

  • an antenna for receiving the signal;

    m stages where m is an integer of at least three, including,a first stage having,means for filtering and amplifying the received signal,a local oscillator for generating a first local oscillator signal, anda first mixer connected to said received signal filtering and amplifying means and to said local oscillator, said first mixer for mixing said first local oscillator signal with said filtered and amplified receive signal to down-convert frequency of said filtered and amplified received signal to a first IF frequency,a second stage having,means for filtering and amplifying said first IF frequency received signal,a first frequency divider connected to said local oscillator, said first frequency divider for dividing by two the frequency of said first local oscillator signal to develop a second local oscillator signal, anda second mixer connected to said first IF frequency received signal filtering and amplifying means and to said first frequency divider, said second mixer for mixing said second local oscillator signal with said filtered and amplified first IF frequency received signal to down-convert the frequency of said filtered and amplified first IF frequency received signal to a second IF frequency,an (m-1)st stage having,means for filtering and amplifying a (m-2)nd IF frequency received signal,a (m-1)st frequency divider for dividing by two the frequency of a (m-2)nd local oscillator signal to develop an (m-1)st local oscillator signal, andan (m-1)st mixer connected to said (m-1)st IF frequency received signal filtering and amplifying means and to said (m-1)st frequency divider, said (m-1)st mixer for mixing said (m-1)st local oscillator signal with a filtered and amplified (m-2)nd IF frequency received signal to down-convert the frequency of said filtered and amplified (m-2)nd IF frequency received signal to a (m-1)st IF frequency,an mth stage having,means for filtering and amplifying said (m-1)st IF frequency received signal, anda mth mixer connected to said (m-1)st IF frequency received signal filtering and amplifying means and to said (m-1)st frequency divider, said mth mixer for mixing said (m-1)st local oscillator signal with said filtered and amplified (m-1)st IF frequency received signal to down-convert the frequency of said filtered and amplified (m-1) IF frequency received signal to an output frequency; and

    means for filtering and amplifying said output frequency received signal and wherein said first local oscillator signal has frequency equal to one half the difference in frequency between said 1540 f0 frequency and said output frequency.

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