Receiver for pseudo-noise signals from a satellite...

Details Receiver for pseudo-noise signals from a satellite... Receiver for pseudo-noise signals from a satellite...

2000-09-05

2002-08-27

Cuchlinski, Jr., William A. (Department: 3661)

Communications: directive radio wave systems and devices (e.g.,

Directive

Including a satellite

C455S296000, C375S136000

Reexamination Certificate

active

06441780

ABSTRACT:

TECHNICAL FIELD
The invention relates to radio navigation and, more specifically, it relates to receivers of pseudonoise signals of the satellite radio navigation systems (SRNS) GPS (USA) and GLONASS (Russia) performing simultaneous reception of the signals of the C/A codes of these systems in the L
1
frequency range.
BACKGROUND OF THE INVENTION
The receivers of digital pseudonoise signals of the SRNS GLONASS (cf. ‘Global Navigational Satellite System “GLONASS”. Interface Control Document. KNITS VKS Russia “, 1995) [1] and GPS (cf. “Global Position System. Standard Positioning Service. Signal Specification.” USA, 1993) [2] are now widely used for finding the coordinates (latitude, longitude, height), speed of objects, and time. The fundamental distinctions between the SRNS GPS and the GLONASS consist in the use of different, although adjacent, frequencies on the L
1
band, use of different pseudonoise modulating codes and use of both code and frequency division of signals of the different satellites in the system. Thus, during operation on the L
1
frequency band the SRNS GPS satellites transmit signals modulated by different pseudonoise codes on one carrier frequency of 1575.42 MHz while the SRNS GLONASS satellites transmit signals modulated by the same pseudonoise code on different carrier (lettered) frequencies laying in the adjacent frequency zone. The nominal values of the lettered frequencies in the SRNS GLONASS system for the L
1
frequency range are set up according to the following rule:
f
j,i
=f
j,0
+i·&Dgr;f
j
,
where
f
j,i
are the nominal frequency values
f
j,0
is the zero lettered frequency;
i is the number of letters;
&Dgr;f
j
is the spacing between the lettered frequencies.
For the L
1
range f
1,0
=1602 MHz, &Dgr;f
1
=0.5625 MHz.
The distinctions existing between the SRNS GPS and GLONASS signals stipulated by the code division in the SRNS GPS and the frequency division in the SRNS GLONASS result in different hardware used for reception and correlation processing of these SRNS signals to allow one to carry out the radio navigation measurements. Known in the art (for example, from Global Positioning System (GPS) Receiver RF Front End. Analog-Digital Converter, (FIG.
1
), Rockwell International Proprietary Information Order Number. May 31, 1995 [3], is a pseudo-random noise signal receiver comprising a radio-frequency converter including a low-noise amplifier, a filter, a first mixer, a first intermediate frequency amplifier, a quadrature mixer, two quantizers for the inphase and quadrature channels, a signal shaper producing a first heterodyne frequency (1401.51 MHz), a divider producing a signal of a second heterodyne frequency from the signal of the first heterodyne frequency, and a correlation processing unit.
The device solves a technical problem of reception and correlation processing of the SRNS GPS signals for performing the radio navigation measurements. This device does not allow one to solve the problem of reception and correlation processing of the SRNS GLONASS signals.
Also known in the art (cf. FIG. 9.2 on pages 146 to 148 in the book “Network Satellite Systems”, by V. S. Shebshaevich, P. P. Dmitriev, N. V. Ivantsevich, et all. Moscow, “Radio i Syaz”, 1993)[4]) a receiver of the SRNS GLONASS pseudonoise signals (“Single-Channel Users' Apparatus “ACH-
37
” for the GLONASS Systems”). The receiver comprises an antenna, a low-noise amplifier-converter, a radio-frequency converter, a digital processing device, and a navigational processor. The low-noise amplifier-converter includes band-pass filters, an amplifier and a first mixer. The radio-frequency converter includes an intermediate-frequency amplifier, a phase demodulator, a second mixer, with a mirror channel phase suppressor, a limiter and a synthesizer of lettered frequencies operating on the signals of a reference generator. The digital processing device includes a pseudo-random sequence generator (PSG) with a digital clock-signal generator of the PSG system, a digital Doppler carrier drift generator, and a phase-code converter with a storage unit for storing the digital samples. The navigational processor is based on a microprocessor series 1806BM2. The lettered frequency synthesizer generates output signals according to the lettered frequencies of the received SRNS GLONASS signals. The spacing between the lettered frequencies generated by the synthesizer is equal to 0.125 MHz. The first heterodyne frequency signal is produced by multiplying the synthesizer output signal by four, while the second heterodyne frequency signal is produced by dividing the frequency at the output of the frequency synthesizer by two. The receiver solves the technical problem of reception and correlation processing of the SRNS GLONASS signals for the next radio navigation measurements and positioning, however, it does not allow one to solve the problem of reception and correlation processing of the SRNS GPS signals.
In spite of the difference between the SRNS GPS and GLONASS, their similarity on designation, ballistic build-up of the orbital groups of satellites and used frequency range allows one to formulate and solve the problems associated with the creation of the receivers capable of processing the signals of these two systems. The result achieved consists in a high reliability, authenticity and accuracy of defining the location of an object, in particular, due to a possibility of selecting a working constellations of satellites with the best geometrical parameters [4, page 160]. Known among the devices performing the reception and correlation processing of the SRNS GPS and GLONASS signals is a receiver of SRNS GPS and GLONASS signals operating in the L
1
frequency range, described in ([4], page 158-161, FIG. 9.8). The receiver comprises an antenna, a radio-frequency converter, a reference generator and a processor for primary processing. The radio-frequency converter comprises a frequency converter (“duplexer”) performing the frequency division of the SRNS GPS and GLONASS signals, band-pass filters and amplifiers in the GPS and GLONASS channels, a mixer, a switchboard applying the SRNS GPS or GLONASS signals to the signal input of the mixer, a switchboard applying the first heterodyne signal to the reference input mixer for the GPS channel or the GLONASS channel. Due to the appropriate choice of the heterodyne signal frequency, the first intermediate frequency (IF) is constant for the SRNS GPS and GLONASS signals and all subsequent operations of signal processing are common for both systems. The processor for primary signal processing includes a multiplexer with a ROM memory unit, a digital generator of lettered frequencies, a digital correlator, a PSG generator and a microprocessor. A disadvantage of this device is that the reception, conversion and correlation signal processing of each SRNS is carried out in series using the same radio channel thereby increasing the time required for the subsequent processing for obtaining the navigational information. Furthermore, the receiver includes a complicated switched high-frequency synthesizer for generation of two different heterodyne signals used for processing the SRNS GPS and GLONASS signals simultaneously.
Among the integrated receivers of pseudonoise SRNS GPS and GLONASS signals in question there is also known a device described by Riley S., Howard N., Aardoom E., Daly P., Silvestrin P. in “A Combined GPS/GLONASS High Precision Receiver for Space Applications”), Proc. Of ION GPS-95, Palm Springs, Calif., U.S., Sep. 12-15, 1995, pp.835-844) [5] which solves the problem of simultaneous reception of signals of both SRNS types. This receiver is taken as a prior art.
A block diagram of the receiver for reception of the SRNS GPS and GLONASS signals, taken as a prior art, is shown in
FIGS. 1-3
. The prior art receiver (
FIG. 1
) comprises an antenna
1
, a radio-frequency converter
2
, a digitizer
55
and an N-channel digital correlator
3
connected in series,

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