EP0079689A2
Expired / Lapsed
EP
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Global positioning system receiver
Assignee: Unisys Corp
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Filing: 1982-10-20
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Granted: —
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Expires: 2002-10-20
Abstract
Abstract In a Global Positioning System type of navigation system, a biphase modulated radio frequency input signal is applied to the "front end" (11) of a double heterodyne receiver having a second intermediate frequency stage which operates in the audio frequency range. The audio output signal is phase locked to a 1 KHz reference signal and is applied to a microprocessor (24) for processing via an interface circuit which includes a relatively simple amplitude detector (51) and a biphase detector (54). The microprocessor (24) also controls the phase shifting of a pseudorandom noise code generator (70) whose output is modulated with the output of the first intermediate frequency stage of the receiver.
Inventors
- 👤 Reuben Edwin Maine
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 05:45
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/32; G01S19/24; G01S19/26
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
221 words
A receiver for use in a navigation system characterised in that it comprises a voltage controlled oscillator (28); means (15) for generating a plurality of signals having phase locked frequencies responsive to the voltage controlled oscillator; first mixing means (14) responsive to a biphase modulated radio frequency input signal and a first signal from the phased locked signal generator means (15); second mixing means (21) responsive to the output of the first mixing means (14) and a second signal from the phase locked signal generator means (15), the output of the second mixing means being in the audio frequency range; audio processing circuit means (50), responsive to a reference signal phase locked to the voltage controlled oscillator (28) and to the audio output signal of the second mixing means (21), including means (51) for detecting the amplitude of the audio output signal, means (53-56, 64) for providing a fast frequency control signal for the voltage controlled oscillator (28), and means (19) for phase shifting the reference signal; and processing means (24), responsive to the output of the audio processing circuit means (50), for providing a coarse frequency signal which is summed with the fast frequency control signal and applied to the voltage controlled oscillator (28) for controlling the phase shifting means (191, and for obtaining data from the audio output signal.
Claim 2
Dependent Claim
221 words
A receiver for use in a navigation system characterised in that it comprises a voltage controlled oscillator (28); means (15) for generating a plurality of signals having phase locked frequencies responsive to the voltage controlled oscillator; first mixing means (14) responsive to a biphase modulated radio frequency input signal and a first signal from the phased locked signal generator means (15); second mixing means (21) responsive to the output of the first mixing means (14) and a second signal from the phase locked signal generator means (15), the output of the second mixing means being in the audio frequency range; audio processing circuit means (50), responsive to a reference signal phase locked to the voltage controlled oscillator (28) and to the audio output signal of the second mixing means (21), including means (51) for detecting the amplitude of the audio output signal, means (53-56, 64) for providing a fast frequency control signal for the voltage controlled oscillator (28), and means (19) for phase shifting the reference signal; and processing means (24), responsive to the output of the audio processing circuit means (50), for providing a coarse frequency signal which is summed with the fast frequency control signal and applied to the voltage controlled oscillator (28) for controlling the phase shifting means (191, and for obtaining data from the audio output signal.
Claim 3
Dependent Claim
56 words
A receiver according to claim 1, characterised in that it further includes correlator means (17), coupled between the first and second mixing means (14, 21), for modulating the output of the first mixing means with the output of local coding means which is responsive to the processing means (24) and to the phase shifting means (19).
Claim 4
Dependent Claim
41 words
A receiver according to claim 1 or 2, characterised in that it further includes gain control means (62, 63) responsive to the processing means (24) for controlling the gain of a wideband amplifier (16) associated with the first mixing means (14).
Claim 5
Dependent Claim
29 words
A receiver according to any of the preceding claims, characterised in that the amplitude detecting means (51) includes a diode detector and filter coupled to an analogue-to-digital converter (62).
Claim 6
Dependent Claim
59 words
A receiver according to any of the preceding claims, characterised in that the audio processing circuit means (50) further includes biphase detector means (54) responsive to the audio output signal and to the reference signal, and in that the error signal of the biphase detector is amplified by a d.c. amplifier (56) to provide the fast frequency control signal.
Claim 7
Dependent Claim
30 words
A receiver according to claim 5, characterised in that the audio processing circuit means (50) further includes a threshold detector (61) responsive to the output of the d.c. amplifier (56).
Claim 8
Dependent Claim
30 words
A receiver according to any of the preceding claims, characterised in that the second mixing means (21) further includes a narrow band amplifier (201 and a tuned audio amplifier (22).
Claim 9
Dependent Claim
38 words
A receiver according to any of the preceding claims, characterised in that the means (15) for generating a plurality of signals having phase locked frequencies includes a plurality of frequency multipliers responsive to the voltage controlled oscillator (28).
References Cited (Backward Citations)
No citation records indexed.
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