Receiver for satellite navigational positioning system

• US 4,232,389 A
• Filed: 04/09/1979
• Issued: 11/04/1980
• Est. Priority Date: 04/09/1979
• Status: Expired due to Term

• Current Assignee: JMR Instruments Incorporated
• Original Assignee: JMR Instruments Incorporated
• Inventors: Loiler, Roger D.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US06/028,266
• Time in Patent Office: 575 Days
• Field of Search: 178/67, 178/69.1, 325/329, 325/330, 325/419, 329/50, 329/122, 329/123, 455/12
• US Class Current: 455/3.02
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence

Abstract

A receiver which responds to United States Navy Satellite Navigational Positioning System (NNSS) transmissions for precise geodetic location of a position on the earth'"'"'s surface is provided. The receiver of the invention is constructed to use the radio frequency carrier of the phase modulated signals transmitted by the Transit satellites in the NNSS system to recover accurate time interval data.

Claims

1. A receiver for use in a satellite system, said system comprising a plurality of satellites each of which includes means for producing a radio frequency carrier and a clock having a frequency related to the frequency of the carrier, said carrier being phase-modulated with digital data, and said clock being adjustable in response to injection signals from a ground station to provide a precise repeatable time interval during which the digital data is transmitted, said receiver including:

a receiver system phase-locked with the radio frequency carrier from the satellite and including a heterodyne mixer for receiving the radio frequency carrier, means connected to said heterodyne mixer and including a phase detector for recovering the digital data from the carrier, a stable local oscillator for supplying a reference signal to said phase detector, first circuit means including a voltage controlled oscillator connected to the phase detector and responsive to a phase error signal from the phase detector for supplying a heterodyne signal to the mixer having a predetermined frequency relationship with the carrier, and second circuit means connected to said stable local oscillator and to said first circuit means for producing an output timing signal having a frequency which is a predetermined sub-multiple of the frequency of said carrier.

2. The receiver defined in claim 1, in which said first circuit means includes a frequency multiplier interposed between the output of the voltage controlled oscillator, and the heterodyne mixer for multiplying the frequency of the output of the voltage controlled oscillator by a predetermined multiplier N.

3. The receiver defined in claim 2, in which said second circuit means includes an adder circuit connected to the output of the voltage controlled oscillator, and a frequency divider circuit connected to the output of the stable local oscillator and to the adder for supplying a signal to the adder whose frequency is 1/N of the frequency of the local oscillator.

4. The receiver defined in claim 3, in which said second circuit means includes a divider circuit connected to the output of the adder to divide the frequency of the output signal from the adder by a divisor K.

5. The receiver defined in claim 4, and which includes means for deriving a Doppler frequency output from the output of the voltage controlled oscillator.

6. The receiver defined in claim 4, and which includes a phase-locked loop connected to the phase detector and responsive to the detected output thereof, for recovering the satellite clock signal.

7. A receiver for use in a satellite system which comprises a plurality of satellites each including means for producing a radio frequency carrier and a clock having a frequency related to the frequency of the carrier, said carrier being phase modulated with digital data, and said clock being adjustable in response to injection of signals from a ground station to provide a precise repeatable time interval during which the digital data is transmitted, said receiver including:

circuitry for receiving the radio frequency carrier, phase detector means coupled to said circuitry for recovering the digital data which is phase modulated on the carrier; and

further circuitry connected to said first-named circuitry and responsive to the radio frequency carrier received thereby for producing a timing signal having a predetermined frequency relationship with said carrier.

8. The receiver defined in claim 7, in which said first-named circuitry includes a local oscillator, and in which said further circuitry includes circuit means for rendering the frequency of the timing signal produced thereby independent of frequency drifts of said local oscillator.