Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
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
C455S269000, C375S136000
Reexamination Certificate
active
06441781
ABSTRACT:
FIELD OF TECHNOLOGY
The invention relates to radio navigation and, more specifically, it relates to digital correlators of receivers used for reception of the pseudo-noise 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 L1 frequency range.
STATE OF THE ART
The receivers of pseudo-noise (noise-like) 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 establishing 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 L1 band, use of different pseudo-noise modulating codes and use of both code and frequency division of signals of the different satellites in the system. Thus, during operation on the L1 frequency band the SRNS GPS satellites transmit signals modulated by different pseudo-noise codes on one carrier frequency 1575.42 MHz while the SRNS GLONASS satellites transmit signals modulated by the same pseudo-noise code on different carrier (letter) frequencies laying in the adjacent frequency zone.
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.
The typical SRNS receiver operates with a complex noise-like signal (NLS) consisting of a plurality of radio signals radiated by the SRNS satellites, a noise component, as well as a component due to the interference caused by the repeated reflection of the signals from various surface areas, buildings, etc.
Known in the art is a SRNS GPS receiver of pseudo-noise signals (cf.
FIG. 1
in the “Global Positioning System (GPS) Receiver RF Front End. Analog-Digital Converter”, Rockwell International Proprietary Information Order Number. May 31, 1995) [3], 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 signal for the purpose of consequent radio navigation measurements, however, it 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 146-148 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 pseudo-noise signals (“Single-Channel Users' Equipment ‘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 mixer. The radio-frequency converter includes an amplifier, a phase demodulator, a second mixer, a limiter and a lettered frequency synthesizer operating on the signals of a reference generator. The device includes a pseudorandom sequence generator (PSG) with a digital clock-signal generator of the PSG, a digital Doppler carrier drift generator, and a phase-code converter with a storage unit for storing the digital samples. The lettered frequency synthesizer generates output signals according to the lettered frequencies of the received SRNS GLONASS signals. The spacing of 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 to provide the consequent 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 existing 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 in the art 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 L1 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 dupleyer performing frequency division of the SRNS GPS and GLONASS signals, band-pass filters and amplifiers of the GPS and GLONASS channels, a mixer, a switch applying the SRNS GPS or GLONASS signals to the signal input of the mixer, a switch applying the first heterodyne signal to the reference input mixer for the GPS channel or the GLONASS channel. Due to the respective frequency shaping of the heterodyne signal, the first intermediate frequency 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 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 sequence.
Also known in the art is a receiver of the SRNS GPS and GLONASS signals in the L1 frequency range (cf. “Riley S., Howard N., Aardoom E., Daly P., Silvestrin P. “A Combined GPS/GLONASS High Precision Receiver for Space Applications”, Palm Springs, CA, US, Sept. 12-15, 1995, pp.835-844) [5], which solves the problem of simultaneous reception of signals of both types of SRNS and the parallel correlation processing of these signals. The receiver of SRNS signals described in [5] comprises an antenna, a radio-frequency converter with a digitizer and N digital correlators connected in series. The receiver described in [5], performs procedures of reception, search (detection) and tracing of signals typical for the SRNS receivers. These procedures consist in the following. For detection, tracing and determination of parameters of the received SRNS signals, these signals are amplified, converted into IF-signals and digitized in the radio-frequency unit of the receiver and, finally, the signals are demodulated using the digital correlation technique in the N correlators processing the signals of individual SRNS satellites. The typical procedures performed by the digital correlator of the SRNS signal receiver consist in correlation of the received NLS signal by multiplying its digital readouts by the local copy of the sought signal generated inside the c
Fedotov Boris Dmitrievich
Ivanov Vladimir N.
Korotkov Alexander N.
Malashin Viktor I.
Pisarev Serguey B.
Cuchlinski Jr. William A.
Nguyen Thu
Samsung Electronics Co,. Ltd.
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