The invention relates to field of radio navigation can also be used in a navigational equipment of the users of satellite radio navigation systems (SRNS) and, mores specifically, in radio receiving equipment performing simultaneous reception of signals, such as SRNS xe2x80x9cGPSxe2x80x9d (USA) and xe2x80x9cGlonassxe2x80x9d (Russian Federation).
It is well known (cf.  less than  less than Onboard Devices of Satellite Radio Navigation) I. V. Kudryavtsev, I. N. Mishchenko, A. I. Volynkin, et al., Ìoscow, Transport Publishers, 1988 pp. 13-15 [1],  less than  less than Network Satellite Radio Navigation Systemsxe2x80x9d, V. S. Shebshaevich, O. O. Dmitriev, N. V. Ivantsevich et al., Moscow, Radio i Svyaz Publishers, 1993, p.35 [2]. The signals, radiated by the navigational artificial satellites of the Earth (NIS)/SRNS xe2x80x9cGPSxe2x80x9d are radio signals modulated by the xe2x80x9cC/Axe2x80x9d and xe2x80x9cPxe2x80x9d in-phase codes: (0, xcfx80) and (+xcfx80/2, xe2x88x92xcfx80/2) respectively. These signals are transmitted on two frequency bands: in a range L1 (carrier frequency 1575.42 MHz) and in a range L2 (carrier frequency 1227.6 MHz). Signals of the frequency band L1 are modulated by the xe2x80x9cC/Axe2x80x9d and xe2x80x9cPxe2x80x9d codes and the signals of the frequency band L2 are modulated by the xe2x80x9cPxe2x80x9d code. The first code (code xe2x80x9cC/Axe2x80x9d) is generated using the law of pseudo-random sequence (PRS) with a period of 1 ms and a clock frequency of 10,023 MHz; the second code (code xe2x80x9cPxe2x80x9d) is generated under the pseudo-random squence law with a period of about 7 days and a clock frequency of 10.23 MHz. The xe2x80x9cC/Axe2x80x9d code transmitted on the frequency band L1 and known as a xe2x80x9cstandard precisionxe2x80x9d code is open for all customers of navigational information and is used in a radio navigational equipment of xe2x80x9cstandard precisionxe2x80x9d, this class including the claimed device, while the xe2x80x9cxe2x80x9d code is used in a special equipment of a higher precision.
To identify the signals radiated by various NIS3 satellites, the code division of the SRNS xe2x80x9cGPSxe2x80x9d signals is used.
In contrast to the SRNS xe2x80x9cGPSxe2x80x9d, in the xe2x80x9cGlonassxe2x80x9d pseudo-random squence (for example, cf. [2], pages 28-30), the frequency division of signals radiated by different NIS3 is accepted. The NIS3 SRNS xe2x80x9cGlonassxe2x80x9d signals are identified by the nominal value of their carrier (xe2x80x9cletteredxe2x80x9d) frequency lying in an assigned frequency range. Two (j=1, 2) frequency band F1 and F2 are provided for the lettered frequencies. The nominals of the lettered frequencies are formed according to the following rule:
fj,i=fj,0+ixcex94fj,
xc3xa3xc3xa4xc3xa5:
fj,i are the nominal of the lettered frequencies;
fj,0 is the zero lettered frequency;
i are the numbers of the letters in each band;
xcex94fj is the interval between the lettered frequencies.
For the frequency F1 (near 1600 MHz)xe2x88x92f1,0=1602 MHz, xcex94f1=0.5625 MHz; for the frequency F2 (near 1240 MHz)xe2x88x92f2,0=1246 MHz, xcex94f2=0.4375 MHz.
The lettered frequencies among the functioning NIS3 satellites are allocated by a special almanac transmitted in the control information frame.
Similarly to the xe2x80x9cGPSxe2x80x9d satellite radio navigation system, each NIS3 of the xe2x80x9cGlonassxe2x80x9d satellite radio navigation system signals in both frequency bands F1 and F2 The SRNS xe2x80x9cGlonassxe2x80x9d signals on the frequency band F1 are modulated by PRS codes of two types: xe2x80x9cstandard precisionxe2x80x9d (with a clock frequency of 0.511 MHz) and xe2x80x9chigh precisionxe2x80x9d (with a clock frequency of 5.11 MHz), i.e. similarly to the xe2x80x9cC/Axe2x80x9d and xe2x80x9cPxe2x80x9d code modulations by codes on the frequency band L1 of the SRNS xe2x80x9cGPSxe2x80x9d signals of the xe2x80x9cGlonassxe2x80x9d SRNS in the frequency band F2 and similarly to the SRNS xe2x80x9cGPSxe2x80x9d signals in the frequency band L2 are modulated only by the high-precision PRS codes. The xe2x80x9cstandard precisionxe2x80x9d code transmitted in the frequency band F1 is open for all users of the navigational information and is used in the xe2x80x9cstandard precisionxe2x80x9d radio navigational equipment whose class includes the claimed device, while the xe2x80x9chigh-accuracyxe2x80x9d code is used, as a rule, in a special high-precision equipment.
The differences existing between the signals of the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d due to the code division at one carrier in the SRNS xe2x80x9cGPSxe2x80x9d and frequency division at several carriers defined by lettered frequencies in the SRNS xe2x80x9cGlonassxe2x80x9d result in differences in technical means used for the reception of the signals of satellite radio navigation systems for conversion them into such a form that enables the subsequent radio navigation measurements to be carried out.
For example, known from the xe2x80x9cGlobal Positioning System (GPS) Receiver RF Front End. Analog-Digital Converter. Rockwell International Proprietary Information Order Number. May 31, 1995 greater than  greater than , FIG. 1 [3] is a device used for reception of signals from the SRNS xe2x80x9cGPSxe2x80x9d, comprising a low-noise amplifier, a filter, a first mixer, a first intermediate frequency amplifier, a quadrature mixer two quantizers for in-phase and quadrature channels, a first heterodyne frequency oscillator (1401.51 MHz), and a divider forming of a second heterodyne frequency signal from the first heterodyne frequency signal.
This device performs the technical task of reception and conversion of the SRNS xe2x80x9cGPSxe2x80x9d signals to a forms permitting the customer to subsequently carry out the corresponding radio navigation measurements. The device does not allow one to receive the SRNS xe2x80x9cGlonassxe2x80x9d signals.
The reference book  less than  less than Satellite Radio Navigation Network Systemsxe2x80x9d, V. S. Shebshaevich, P. P. Dmitriev, H. V. Ivantsevich, et al., Ìoscow, Radio i Syaz Publishers. 1993, pp. 147-148 [2], discloses a device for reception of the SRNS xe2x80x9cGlonassxe2x80x9d signals (xe2x80x9cSingle-Channel Equipment for ASN-37 Customersxe2x80x9d). The device comprises an input filter, a low-noise amplifier, a first mixer, an intermediate-frequency amplifier, a phase demodulator, a second mixer with phase suppression of the mirror channel, a limiter, a lettered-frequency synthesizer, and a local oscillator to generate signals of heterodyne frequencies. The lettered-frequency synthesizer produces its own output signals according to the lettered frequencies of the SRNS xe2x80x9cGlonassxe2x80x9d signals being received. The lettered frequency spacing provided by the synthesizer is 0.125 MHz. The first heterodyne frequency signal is formed as a result of multiplication of the output frequency signal of the synthesizer by a factor of 4, and the signal of the second heterodyne frequency is formed as a result of division of the synthesizer output frequency signal by 2.
This device performs the technical task of reception and conversion of the SRNS xe2x80x9cGlonassxe2x80x9d signals to bring them a form permitting the customer to perform the corresponding radio navigational measurements. The device does not allow one to solve the problem of reception of the SRNS xe2x80x9cGPSxe2x80x9d signals.
In spire of differences existing between the SRNS xe2x80x9cGPSxe2x80x9d and the xe2x80x9cGlonassxe2x80x9d, they have an identical ballistic construction of the orbital group of the NIS3 satellites and allocated frequency band allowing one to state and solve the problems associated with the creation of an integrated navigational equipment for the users of the signals of these two radio navigation systems. The achievable result consists in higher reliability, authenticity and precision of definition of the object location, in particular, due to a possibility of a choice of working constellations of the NIS3 with the best geometrical factors  less than  less than Network Satellite Radio Navigation Systemsxe2x80x9d (V. S. Shebshaevich, P. P. Dmitriev, N. V. Ivantsevich et al., Moscow, Radio i Svyaz Publishers, 1993, p. 160 [2].
Known among such devices ( less than  less than Network Satellite Radio Navigation Systemsxe2x80x9d (V. S. Shebshaevich,, P. P. Dmitriev, N. V. Ivantsevich et al., Moscow, Radio i Svyaz Publishers, 1993, pp.158-161 [2], FIG. 9.8.xe2x80x9d) is a device performing the task of reception of the SRNS xe2x80x9cGPSxe2x80x9d signals in the frequency band L1 and the xe2x80x9cGlonassxe2x80x9d signals in the frequency band F1 and converting them to a form permitting one, using a digital processor (primary and navigational processors) to carry out the subsequent radio navigational measurements and definition of the location of the object. Such a known device comprises a frequency divider (xe2x80x9cdiplexerxe2x80x9d) performing frequency division of the of the xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals, satellite radio navigation system, band-pass filters and low-noise amplifiers of xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d channels, a mixer, a SHF switch feeding the SRNS xe2x80x9cGPSxe2x80x9d or xe2x80x9cGlonassxe2x80x9d signals to the signal input of the mixer, a SHF switch feeding the first heterodyne signal of the xe2x80x9cGPSxe2x80x9d channel or xe2x80x9cGlonassxe2x80x9d channel to the reference input of the mixer. Due to the corresponding frequency shaping of the heterodyne signal the first intermediate frequency is constant for the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals and the entire following channel of the device is realized as common for these signals.
A specific feature of such a device is that the reception and conversion of the SRNS signals is effected in time in succession using the same radio channel, and this increases the time consumed for the subsequent processing in order to obtain the navigational information. Besides, the implementation of the device requires a complex high-frequency switched frequency synthesizer to produce two different heterodyne signals used for conversion of the signals SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d respectively.
Also known in the art is a device for reception of the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals described in  less than  less than Riley S., Howard N., Aardoom E., Daly P., Silvestrin P. xe2x80x9cA Combined GPS/GLONASS High Precision Receiver for Space Applicationsxe2x80x9d/Proc. of ION GPS-95, Palm Springs, Calif., US, Sep. 12-15, 1995 greater than  greater than  pp. 835-844, FIG. 2 [4], which performs simultaneous reception of SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals. The functionally completed part of this device solving the problem of reception of the SRNS xe2x80x9cGPSxe2x80x9d signals on the frequency band L1 and the xe2x80x9cGlonassxe2x80x9d signals on the frequency band F1 and producing output signals to be used for the navigational measurements is taken as a prior art.
The block diagram of the prior art device is shown in FIG. 1.
The device taken as a prior art, comprises (FIG. 1) an input unit 1 whose input is a signal input of the device, a unit 2 of the first signal frequency converter comprising a first amplifier 3, a mixer 4 and a second amplifiers 5 connected in series, a first channel 6 and a second channel 7 of the second signal frequency converter, and a module 8 producing clock signals and heterodyne frequency signals said module comprising an independent clock generator and three units or frequency synthesizers used for producing signals of heterodyne frequencies . (not shown in FIG. 1).
The channel 6 of the second signal frequency converter comprises a filter 9 and a mixer 10 connected in series.
The channel 7 of the second signal frequency converter comprises a filter 11 and mixer 12 connected in series.
The inputs of the filters 9 and 11 are respectively inputs of the first 6 and second 7 channels of the second signal frequency converter and are connected to the output of the amplifier 5, i.e. to the output of the unit of the first signal frequency converter 2. The input of the amplifier 3, i.e. the input of the unit 2, is connected to the output of the unit 1. The reference input of the mixer 4 of the unit 2 of the first signal frequency converter is connected to the signal output of the first heterodyne frequency of the module 8 formed by the signal outputs of the first heterodyne frequency (not shown in FIG. 1). The reference inputs of the mixers 10 and 12 of the first 6 and second 7 channels of the second signal frequency converter are connected respectively to the outputs of the signals of the second and third heterodyne frequencies of the module 8, formed by the outputs of the corresponding units producing the signals of the second and third heterodyne frequencies (not shown in FIG. 1).
The outputs of the mixers 10 and 12 the first of 6 and second 7 channels of the second signal frequency converter and the output of the clock-frequency signal of the module 8 produced at the output of the clock-frequency signal generator (not shown in FIG. 1) are the outputs of the device taken as a prior art.
The prior art device operates as follows.
The SRNS xe2x80x9cGPSxe2x80x9d signals of the frequency band L1 and the xe2x80x9cGlonassxe2x80x9d signals of the frequency band F1 from the antenna (not shown in FIG. 1) through the input unit 1 performing frequency filtering of the signals of the given frequency band are applied to the input of the unit of 2 the first signal frequency converter.
In the unit 2 the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals of the frequency band L1 (F1) are amplified in the first amplifier 3, converted by frequency in the mixer 4 and are amplified in the second amplifier 5 (intermediate-frequency amplifier).
For the first frequency conversion performed in the unit 2, device makes use of the signal of the first heterodyne frequency fxc3xa31=1416 MHz fed from the corresponding output of the module 8. In the module 8 the signal of the first heterodyne frequency fxc3xa31 is synthesized with the help of an independent unit producing the signal of the first heterodyne frequencyxe2x80x94the first frequency synthesizer (not shown in FIG. 1).
The SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals of the frequency band L1 (F1) converted in the unit 2 are applied to the inputs of the first channel 6 and second channel 7 of the second signal frequency converter, i.e. to the inputs of the filters 9 and 11. Each of these filters processes the signals of one of the SRNS, namely, the filter 9 is used for filtering the SRNS xe2x80x9cGPSxe2x80x9d signals and the filter 11 is used for filtering the SRNS xe2x80x9cGlonassxe2x80x9d. signals.
The frequency-converted signals are filtered with the help of the filters 9 and 11 to remove the out-of-band interference and allocated in the systems (xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d) in each of the channels 6 and 7 are fed to the signal inputs of the mixers 10 and 12 respectively.
For the second frequency conversion performed in the channels 6 and 7 the prior art device makes use of the signals of the second and third heterodyne frequencies fxc3xa32=173.9 MHz and fxc3xa33=178.8 MHz synthesized with the help of the corresponding independent units generating signals of the second and third heterodyne frequenciesxe2x80x94the second and third frequency synthesizers (not shown in FIG. 1) incorporated into the module 8. Thus, the signal of the second heterodyne frequency fxc3xa32=173.9 MHz is used for conversion of SRNS xe2x80x9cGPSxe2x80x9d signals in the mixer 10 of the first channels 6 and the signal of the third heterodyne frequency fxc3xa33=178,8 MHz is used for conversion of SRNS xe2x80x9cGlonassxe2x80x9d signals in the mixer 12 of the second channels 7.
The SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals converted with the help of the mixers 10 and 12 are applied to the outputs of the channels 6 and 7 respectively.
The SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals, converted by frequency in the channels 6 and 7, as well as the clock signal generated in the module 8 with the help of an independent clock generator, for example, a quartz-controlled oscillator (not shown in FIG. 1) form the output signals of the devices taken as a prior art.
The output signals of the prior art device are used for performing the radio navigational measurements to obtain the corresponding navigational information. In so doing the output signals are subjected to digital processing, at first in 4-bit analog-to-digital converters (ADC), then in dedicated digital filters and in a special calculator (not shown in FIG. 1). The clock signal generated in the device is used in this case as a clock signal setting the sampling rate with time when effecting the analog-digital conversion.
To carry out the digital processing without any loss of the navigational information, the output signals of the prior art device are matched by their frequency and spectrum. The matching is provided by selecting definite clock and heterodyne frequencies. When doing this in the prior art device, the clock frequency of the next analog-digital conversion, i.e. the time-dependent sampling rate is selected as fò=57.0 MHz. Taking this frequency into account, the agreed values of heterodyne frequencies fxc3xa32=173.9 MHz and fxc3xa33=178.8 MHz for the second frequency conversion of signals are selected, so that the average frequency of SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals on the second intermediate frequency would be close to 14.25 MHz. It ensures a possibility of digital processing in the 4-bit ADC, in which the clock frequency is selected equal to fõ=57.0 MHz (4xc3x9714.25 MHz) and dedicated digital filters are used to allocate the two-bit in-phase and quadrature samples with a frequency of 28.5 MHz (2xc3x9714.25 MHz) [4, page 837].
Thus, in the prior art device the following signals of clock and heterodyne frequencies are generated: a clock frequency of 57.0 MHz, a first heterodyne frequency of 1416 MHz, a second heterodyne frequency of 173.9 MHz, the third heterodyne frequency of 178.8 MHz.
The generation of the above signals of heterodyne frequencies is carried out in the prior art device by means of local oscillators whose complexity is stipulated by the fact that none of the heterodyne frequencies can be obtained from another heterodyne frequency used in the prior art device by simple multiplication or division. Therefore, the heterodyne frequencies are synthesized with the help of three independent synthesizers of heterodyne frequencies which are built-in the module 8 (not shown in FIG. 1), each of which represents an independent radio component whose complexity is stipulated by the high requirements imposed on the stability of the synthesized frequencies (relative frequency instability is 10xe2x88x9211 to 10xe2x88x9212 per second. [5]), since this has a significant effect on the output characteristics of the receiving device as a whole.
The use of complex heterodyne equipment (three independent frequency synthesizers) in the prototype device and a high clock frequency (57.0 MHz) complicates the digitizing equipment and makes it difficult to use the prior art device as a portable (pocket) receiver for determining the position by means of the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals
In this connection, the task of simplifying the equipment generating the clock and heterodyne signals, for example, a decrease of the number of frequency synthesizers is obvious. The possibility of creation of small-size receiver-indicators convenient for use and defining the location by the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals depends on the solution of this problem, and this is especially important, for example, for the case of portable (pocket) receiver-indicators intended for general use by a wide circle of customers.
The basic object of the claimed invention is to the create a device realizing simultaneous reception and conversion of the SRNS xe2x80x9cGPSxe2x80x9dsignals on the frequency band L1 and xe2x80x9cGlonassxe2x80x9d on the frequency band F1 using one common synthesizer for producing the signals of clock and heterodyne frequencies, the clock frequency of the produced signal being matched to the spectrum of the SRNS xe2x80x9cGPSxe2x80x9d and xe2x80x9cGlonassxe2x80x9d signals converted in the device.
This object of the invention is attained by providing a device for reception of signals of satellite radio navigation systems comprising a input whose input is a signal input of the device and the output signals are fed to the first frequency converter comprising a first amplifier whose input is an input of the unit of the first signal frequency converter, a mixer and a second amplifier connected in series to the output of the second amplifier of the first frequency converter, a first channel and a second channel of the second signal frequency converter, each of which comprises a filter whose input is an input of the corresponding channel of the second signal frequency converter and a mixer connected in series, a generator generating a signal of the first heterodyne frequency, and a module producing the signals of the clock and heterodyne frequencies. The signal output of the first heterodyne frequency is connected to the reference input of the mixer of the first signal frequency converter and signal output of the second heterodyne frequency is connected to the reference input of the mixer of the first channel of the second signal frequency converter; the outputs of the channels of the second signal frequency converter and the signal output of the clock and heterodyne frequencies are the outputs of the claimed device, the unit producing the signal of clock and heterodyne frequencies is connected to the output of the unit producing signals of a first heterodyne frequency; units for the first and a second frequency division, respectively, by eight and by 2N, where N=1, 2, 3. The outputs of this unit make, respectively, a signal output of the second heterodyne frequency and a signal output of the clock frequency of the unit producing the signals of the clock and heterodyne frequencies, in which case said signal output of the second heterodyne frequency is connected also to the reference input of the mixer of the second channel of the second signal frequency converter, while in each of the channels of the second signal frequency converter the mixer output is connected to the output of the channel through an controlled-gain amplifier and a threshold device connected in series.
In the device for reception of signals of satellite radio navigation systems the input unit in made as a module including a first band-pass filter, a gain-controlled amplifier and a second band-pass filter connected in series; the control inputs of the gain-controlled amplifiers and control inputs of the threshold devices of both channels of the second signal frequency converter are connected to the outputs of the corresponding digital-to-analog converters whose inputs are control inputs of the device, and the threshold devices of both channels of the second signal frequency converter are made in the form of level-controlled two-bit quantizers.