RU2067771C1 - Receiver/transmitter for satellite navigation systems - Google Patents

Abstract

FIELD: navigation. SUBSTANCE: device has antenna 1, receiver 2, master oscillator 3, preliminary processing units in each channel. Each of said units has frequency-code correlator 4, multiple-function random number generator 3, integrators unit 6 and unit 7 which measures relative distance and velocity. In addition device has interface unit 8, two units 9 and 10 which match levels of signals from communication line, navigation problem solving unit 11, working constellation selection unit 12, two memory units 13, 18, two read-only memory units 14, 19, one re-writing read-only memory unit 15, navigation characteristics input/output unit 16, timer 17 and indicator 20. EFFECT: device receives and processes signals from two satellite navigation systems of "Glonass" or "Navstar" types. 2 cl, 14 dwg

Description

 The present invention relates to the field of satellite radio navigation and can be used to determine the state vector (coordinates, speed and time) of consumers from the signals of two mutually synchronized satellite radio navigation systems (SRNS).

Known receiver SRNS [1] containing a series-connected antenna and pre-amplifiers for two frequency ranges of received signals (L ₁ and L _2, respectively), the outputs of the preamplifiers are connected respectively to the first and second inputs of the frequency converter. The outputs of the specified Converter, in turn, are connected respectively to the inputs of the first or fourth channels for tracking the signal carrier of each of the four satellites and to the input of tracking the delay code, which provides sequential tracking of the signals of the four satellites in time-sharing mode. The outputs of the first and fourth channels for tracking the carrier and the output of the channel for tracking the delay code are connected to the corresponding inputs of the control processor. The output of the control processor is connected to the input of the communication unit, the first output of which is connected to the input of the navigation processor, and the second to the input of the display control unit. The specified receiver-indicator [1] also contains a reference thermostatic generator and a frequency synthesizer.

 The disadvantage of this device [1] is the inability to work with the signals of spacecraft (SC) of two satellite radio navigation systems of the type "Glonass" and "Navstar" at the same time (the receiver-indicator [1] can work on the signals of the satellites of only the Navstar system), which limits the possibility high-precision continuous navigation measurements, especially with incomplete deployment of the spacecraft of the specified system.

In addition, the receiver-indicator [1] provides low accuracy in measuring the state vector of navigation parameters, since in the tracking channel for the code delay of this device, the signal code delay of the first carrier tracking channel with a frequency L ₁ is measured first, then the second carrier tracking channel with a frequency L ₁ etc. those. the device [1] does not ensure the continuity of radio navigation measurements, since the update periods of measurements of code delays with frequencies L ₁ and L ₂ are respectively 250 and 10000 ns. This leads to a decrease in the accuracy of navigation measurements of the consumer state vector, in particular, highly dynamic objects.

These disadvantages are partially eliminated in the receiver-indicator [2] which contains an antenna, preamplifier, two-stage radio frequency converter, a quadrature converter, a reference crystal oscillator and synthesizer, a digital correlator, a control device, a code generator, the first generator controlled by a digital code (GCC), designed to control the generator code, the second GCC, which serves to control the carrier, a control device for selecting a range of operating frequencies L ₁ or L ₂ . The outputs of the digital correlator are connected simultaneously with the input of the bit synchronizer blocks, a filter for the delay tracking circuit, and a carrier tracking filter. From the output of the bit synchronizer, a dedicated navigation message is sent to the first input of the block for solving navigation problems, the second input of the indicated block receives the data of quasidality measurements with time stamps, and the third data of measurements of the rate of range change. In addition, from the output of the control device to the control input of the unit for solving navigation problems, interrupt signals are received. The output of the unit for solving navigation problems is connected to the input of the control device, thereby providing a choice of the operating frequency range L ₁ or L ₂ . The output signals of the control unit go to the input of the reference crystal oscillator and frequency synthesizer, which provide the necessary heterodyne frequencies to the radio path of the device [2] and the clock frequencies of the digital signal processing nodes.

 The advantage of the transceiver [2] is the implementation of the signal processing path (after switching to the intermediate frequency) in digital form. This allows you to increase the stability, accuracy and reliability of the device, to quickly capture the signal in the plane of the uncertainty of the time-frequency and as a result to reduce the time it takes to get the first reference, as well as reduce the overall dimensions and power consumption.

 However, the receiver-indicator [2] has a number of serious drawbacks. First, the device [2] operates on the spacecraft signals only from the Navstar system, which in some cases reduces the accuracy of measuring the parameters of the state vector of the navigation parameters of the consumer. Secondly, to account for the group propagation time of the input signals in the receiver of the device [2], a complex multi-bit frequency synthesizer and calibrator are used, which leads to a significant complication of the receiving path.

The closest in technical essence to the claimed device is a receiver-indicator [3] having a modular structure and including two antennas that provide separate reception of spacecraft signals of the Navstar system in the ranges L ₁ and L ₂ , a module of a two-channel pre-amplifier, the outputs of which are connected respectively to the first and second inputs of the switch of the radio frequency channel, the converter of the radio frequency signal with lowering the range of operating frequencies, thermostatic generator, frequency synthesizer, adapt an analog-to-digital converter (ADC), a digital correlator mixer, a pseudo-random sequence generator (CSP), a control unit for a CSP generator, a digital code controlled generator, a digital carrier frequency generator, a digital signal processing processor, a two-port communication random access memory (RAM), navigation processor, floating point coprocessor, random access RAM and read-only memory (ROM).

 The advantage of the prototype device [3] is the modular organization of the constituent parts of the receiving indicator, which allows for the implementation of the multi-channel principle of constructing consumer equipment (AP) and thereby ensuring the required accuracy of measurement of the vector of navigation parameters. Secondly, the receiver path of this device is constructed in such a way that it does not contain, for example, a Doppler correction elimination scheme or an input signal correlation processing, which allows, in the general case, to implement any number of tracking loops for the measured parameters of the received signals in a digital signal processor, providing the necessary quality and accuracy of measurements.

 However, the prototype device [3] has a number of significant drawbacks that worsen its technical characteristics.

 So, for example, the receiver-indicator [3] provides work only with the signals of the spacecraft of the SRNS Navstar, which leads to a decrease in the accuracy of the measurement of the vector of navigation parameters, especially when the system is not fully deployed or some satellites fail. In addition, the presence in the receiver of the device [3] of the radio frequency channel switch leads to a decrease in the signal-to-noise ratio by about 1.5 dB per one receiving channel. And finally, the device [3] contains only two tracking rings (for the carrier frequency and code) in each receiving channel, which can lead to a breakdown in auto tracking if this receiver-indicator is used to measure the state vector of the navigation parameters of highly dynamic objects or in difficult jamming conditions, and in some cases to the loss of operability of the device.

In the inventive device, the ability to solve the following problems:
the ability to simultaneously receive and process signals from the GLONASS and Navstar spacecraft using the same receiving path, i.e. without switching reception channels,
the implementation of the reception channel of the spacecraft signals using a single frequency conversion in order to enable digital processing of signals in a wide frequency band, as well as eliminate additional spectral components that occur with double frequency conversion in the receiver,
increasing the accuracy of measurements of the consumer state vector by reducing the group delay time of the received GLONASS and Navstar SRNS signals.

 improving the accuracy and reliability of the inventive receiver-indicator due to the introduction of additional circuits for auto tracking on the carrier frequency and code.

Figure 1 presents the functional diagram of the receiver-indicator of satellite radio navigation systems; figure 2 is a functional diagram of a receiver of signals from satellite radio navigation systems; figure 3 is a structural diagram of a frequency synthesizer receiver; figure 4 is a functional diagram of a multi-stage frequency divider synthesizer frequency receiver; figure 5 (a, b, c), respectively, the amplitude-frequency and phase-frequency characteristics, as well as the characteristic time of the group delay of the aqueous broadband filter-preselector of the receiver; in FIG. 6 amplitude-frequency characteristic of the band-pass filter of the intermediate frequency path of the receiver; Fig.7 embodiment of a technical implementation of the analog-to-digital Converter receiver; in Fig.8
functional diagram of the frequency-code correlator; Fig.9 is a functional diagram of a block of integrators; figure 10 functional diagram of a multifunctional generator; in FIG. 11 is a functional diagram of a primary information processing path of a transceiver; on Fig graphic interpretation of the determination of the amplitude value of the envelope of the complex signal; on Fig graphic interpretation of the formation of the Doppler shift of the received signal from the spacecraft SRNS; on Fig diagram of the formation of the anti-vector Doppler shift.

 According to the invention, the receiver-indicator of satellite radio navigation systems (Fig. 1) contains an antenna with an input feeder 1, an output connected to the input of the receiver 2, which provides simultaneous processing in a wide frequency band of the satellite signals of the Glonass and Navstar systems. The reference thermostatic generator 3 generates reference highly stable oscillations with a frequency of 10 MHz and is connected to the control input of the receiver 2. In the receiver 2, after conversion, a grid of operating clock frequencies is provided to ensure the operability of a number of other nodes and blocks of the receiver indicator. The receiver 2 also provides the supply of m-bit digital signals to the first information inputs of the frequency-code correlator 4, thereby providing digital processing of the input information with the support of internal mathematical software.

 The signals received from the spacecraft are modulated by pseudo-random sequences and a navigation message. In the receiver-indicator, it is necessary to generate copies of these SRPs for each of the spacecraft signals, coordinate them according to the temporary position, restore the suppressed carrier taking into account the Doppler shift, and issue a navigation message. For this, the multifunctional generator 5 includes PSP generators that generate sequences, each of which is unique to any of the satellites of the two spacecraft systems. The signals of the pseudo-random sequences ("earlier", "norm", "later") in various combinations for the two spacecraft systems are fed to the second group of information inputs of the frequency-code correlator 4, which, together with the integrator unit 6 and the pseudorange and pseudo-speed calculation unit 7, performs a series functions of the primary processing of information, for example, tracking the code, tracking the frequency shift, estimating the signal-to-noise ratio, initializing and searching for the code, etc.

 The two-port communication OZK 8 serves to exchange information between the signal processing unit 7 and the navigation processor unit, including signal level matching units, a navigation task solution unit 11 and a working constellation selection unit 12, as well as necessary elements of the computing process organization for solving the navigation problem, namely, OZK 13, ROM 14 and RPZU 15.

 The results of solving the navigation problem are fed to the input of the I / O block 16, for the functional support of the operability of which is a timer 17, non-volatile random access memory 18 and ROM 19. The measurement results of the vector of navigation parameters are sent to indicator 20.

 The receiver 2 signals of satellite radio navigation systems (1, 2) contains a broadband filter preselector 21, the input of which receives a signal from the output of the antenna feeder 1. The output of the broadband filter preselector 21 is connected to the first input of the first low-noise amplifier 22, connected to its turn, the output with the input of the band-pass filter 23, the output of which is connected to the first input of the second low-noise amplifier 24. The output of the low-noise amplifier 24 is connected to the input of the mixer 25, to the second input of which the first output of the synthesizer is connected mash 26 frequencies, acting as a local oscillator in this case. The input of the frequency synthesizer 26 is connected to the output of the reference thermostatic generator 3. The output of the mixer 25 is connected to the input of the band-pass filter 27, which provides the separation of signals from the GLONASS and Navstar spacecraft at the differential intermediate frequency. The output of the bandpass filter 27 is connected to the first input of the intermediate frequency amplifier 28. The output of the intermediate frequency amplifier 28 is connected simultaneously with the input of the analog-to-digital converter 29, the output of which is the digital output of the receiver 2, as well as with the input of the automatic gain control unit 30. The output of the latter is connected to the first input of the intermediate frequency amplifier 28, the second input of the second low-noise amplifier 24 and the second input of the first low-noise amplifier 22. The second and third outputs of the frequency synthesizer 26 are connected with a quarter-period shift, thereby providing the formation of a quadrature and common-mode component at the output of the block ADC 29.

 The frequency synthesizer 26 (figure 2, 3) includes a pulse-phase detector 31, the first input of which receives a signal from the output of the thermostatic generator 3. The output signal from the output of the thermostatic generator 3 also goes to the first input of the frequency detector 32. The outputs of the pulse phase detector 21 and frequency detector 32 are connected respectively to the first and second inputs of the adder 33, the output connected to the input of the low-pass filter 34 (low-pass filter). The output of the low-pass filter 34 is connected to the input of a voltage controlled oscillator (VCO) 35, the output of which, in turn, is connected to the input of the mixer 25, thereby providing a 1440 MHz local oscillator signal, as well as with the input of a multi-stage frequency divider 36, thereby forming active frequency synthesizer.

 The multi-stage frequency divider 36 (FIGS. 2, 4) contains a T-flip-flop 37, whose clock input is connected to the output of the voltage-controlled generator 35, and is the input of a multi-stage frequency divider 36.

 The direct output of the T-flip-flop 37 is connected to the clock input of the T-flip-flop 38, and the inverse is connected to the input of the counter-divider 39, from the first output of which a sequence of rectangular pulses with a frequency of 20 MHz is taken and fed to the clock inputs of blocks 4, 5, 6, 7, a second output, a sequence of rectangular pulses with a frequency of 12 MHz is taken, which is fed to the inputs of the clock frequency of blocks 9, 10, 11, 12, the third output of the specified counter is connected respectively to the second inputs of the pulse phase detector 31 and the frequency detector 32. Inverse to trigger stroke 38 is connected simultaneously with the input of the T-trigger 40 and the first input of the 3 AND 41 element. The output of the T-trigger 40 is connected simultaneously to the T-trigger 42 and the second input of the 3 AND 41 element. The output of the T-trigger 42 is connected simultaneously with the third input of the element 3 and 41 and the first control input of the analog-to-digital converter 29. The direct output of the T-trigger 38 is connected to the synchronization input of the T-trigger 43, the output of which is connected to the synchronization input of the T-trigger 44, the output connected to the second control input of the analog-to-digital converter 29 Out d element 3 And 41 is connected to the reset inputs of the T-flip-flop 43 and 44. The signals that are removed from the output of the flip-flops 42 and 44 are fed to the corresponding inputs of the analog-to-digital Converter 29 with a quarter-period offset relative to each other, thereby ensuring quadrature signal processing.

 Figure 5 a, b, c shows, respectively, the amplitude-frequency, phase-frequency characteristics, as well as the time delay characteristic of the group delay of the broadband filter preselector 21 (filter-preselector Cauer).

 Figure 6 presents the amplitude-frequency characteristic of the cascade bandpass filter 27, which provides filtering of the mirror noise of the radio path and the separation (selectivity) of the signals of the spacecraft systems "Glonass" and "Navstar".

The analog-to-digital Converter 29 (Fig.2, 7) contains comparators 45, 46, 47, the first input of which receives a signal from an amplifier 28 of an intermediate frequency. The second input of the comparator 45 is connected to a positive potential that determines the comparison threshold voltage (U _por1 , the second input of the comparator 46 is connected to a negative potential that determines the comparison threshold voltage (U _por2 ), the second input of the comparator 47 is connected to a zero potential that also determines the comparison threshold voltage ( U _por3 ), the outputs of the comparators 45, 46 are connected respectively to the first and second inputs of the OR element 48, the output of which is connected simultaneously with the information inputs of the D-flip-flops 49 and 50. Output the comparator 47 is connected to the information inputs of the D-flip-flops 51 and 52. The clock inputs of the flip-flops 49 and 50 are simultaneously connected to the output of the T-flip-flop 42, the clock inputs of the D-flip-flops 51 and 52 are simultaneously connected to the output of the T-flip-flop 44. The outputs of the D-flip-flops 49 and 51 form the first (sine) pair of samples I ₁ and I ₂ and the outputs of the D-flip-flops 50 and 51 the second (cosine) pair of samples Q ₁ and Q _{2 of the} output information signal.

 The frequency-code correlator 4 (Fig. 1 and Fig. 8) contains a read-only memory 53, to the first-fourth address inputs of which signals from the output of the ADC 29 of the receiver are received, and to the fifth or eighth address inputs of the ROM 53, signals from the output of the generator with digital control 54, the input of which, in turn, receives the calculation data from the data bus of the digital signal processing processor 7. The outputs of the ROM 53 are connected to the corresponding inputs of the multiplying device 55, while the second inputs of this device receive the values of the pseudorandom sequences from the output of the multifunction generator 5. The multiplication results are received at the inputs of the accumulating adders 56, 57, 58, 59, and the three least significant bits of the output of the multiplying device 55 are connected to the inputs of the accumulating adders 56 and 57, and the oldest to the inputs of the accumulating adders 58 and 59. The transfer outputs of the four listed accumulating adders are connected to striation inputs binary counters 60, 61, 62, 63. The reset inputs of said counters are combined with each other and connected to the discharge control output digital signal processing processor 7.

The integrator block 6 (Fig. 11 and Fig. 9) contains N-adequate channels, each of which contains, in turn, on-off keys 64, 65, 66, 67, the first inputs of which receive signals I _n , Q _n , I _E , I _L from the outputs of the binary counters 60, 61, 62, 63 of the frequency-code correlator 4. The second inputs of the on-off keys 64, 65, 66, 67 receive information from the output of the digital processor 7 of the signal processing, the operation mode is selected by supplying a control potential from the control bus of the digital processor 7. The outputs of these on-off keys soy ineny with the clock input of the counter drives 68, 69, 70, 71, respectively. The installation inputs of these drive counters are interconnected and connected to the first output of the control unit 72, the input of which receives a clock frequency of 20 MHz from the control output of the receiver 2. The outputs of these drive counters are connected to the input of registers 73, 74, 75, 76 the inputs of which are interconnected and connected to the second output of the control unit 72. The outputs of these registers are connected to the information inputs of the multiplexer 77, the control inputs of which receive signals from the third to sixth outputs of the control unit 72. The outputs of the first N-th channel of the unit 6 integrators are connected to the information inputs of the multiplexer 78, which is controlled using the node Zh79 priority interruptions, one of the outputs of which is connected to the input of the control unit 72. The input of the priority interrupt unit 79, as well as the input of the ROM control unit 80 and the interface unit 81, receives information from the address and control buses of unit 7. The outputs of the multiplexer 78 and the read-only memory 82 are connected to the input of the key unit 83, which is controlled by the unit 79 priority interrupts. The input of the ROM 82 is connected to the output of the ROM control unit 80. The output of the interface unit 81 is connected to the control input of the dual-port communication RAM 8, and the output of the key unit 83 is connected to the data bus input of the digital signal processing processor 7.

The multi-function generator 5 (FIG. 1 and FIG. 10) comprises a frequency divider 84, the first to fifth outputs of which are connected to the corresponding inputs of the control unit 85, the input of which receives an external potential signal “master / slave”. The output of the control unit 85 is connected to the first input of the clock generator 86, as well as to the other N-channels of the multifunction generator 5. The second input of the clock generator 86 receives a signal from the first output of the pseudo-random sequence control unit 87, the input of which is connected to the control bus of the digital processor 7 signal processing. The first output of the clock frequency driver 86 is connected to the synchronization input of the GLPASS low-precision (ПП) generator and the general-use ПСА generator of the Navstar system, which are based on the ПТ / СА 88 generator. The generator operating mode is selected by connecting the second output of the PSP control unit 87 to the control input of the block 88 and supplying a potential Navstar / Glonass signal depending on the type of spacecraft. In the case of working with the SC of the Glonass system, a signal with a frequency of 511 kHz is received at the input of block 88, and when working with the SC of the system of Navstar, it is 1.023 MHz. The second output of the clock frequency driver 86 is connected to the synchronization input of a high-precision SRP generator (BT code), which is based on block 89. In the case of operation of block 89, a 5.11 MHz signal is received at the synchronization input of block 89. The information input of block 89 is connected to the third output of the pseudo-random sequence control block 87, thereby making it possible to programmatically change the operating mode of the PSP 89 generator. The information inputs of blocks 88 and 89 are connected to the first and second inputs of the multiplexer 90, respectively, the first and second control inputs of which are connected with the fourth and fifth outputs of block 87. At the outputs of the multiplexer 90, depending on the combination of input signals, pseudo-random sequence signals are generated s:
a) for the spacecraft system "Navstar": C / A (norm), CA (earlier), C / A (later),
b) for the Glonass spacecraft system: Fri (normal), Fri (earlier), Fri (later),
for the Glonass spacecraft system: VT (normal), VT (earlier), VT (later).

 The indicated signals of the pseudo-random sequences are fed to the input of the multiplying device 55 of the frequency-code correlator 4. The control outputs of the blocks 88 and 89 are connected respectively to the first and second control inputs of the pseudo-range counter 91, the clock input of which is connected to the 20 MHz clock input of the multifunction generator 5. Information input a pseudo-range counter 91 is connected to the sixth output of the SRP control unit 87, providing an initial pseudo-range vector. The information output of the specified counter 91 is connected to the data bus of block 7.

 The primary information processing section includes a frequency-code correlator 4, an integrator unit 6 and a number of nodes based on a digital signal processing processor 7, while the outputs of the integrator unit 6 are connected to the input of the parameter estimation unit 92, the first output of which is connected to the information input dual-port RAM 8, and the second with ROM control unit 80, the output of which is connected to the address input of ROM 82, on the basis of which an arctangent phase detector of the phase carrier tracking loop is implemented (block 82, digital fil rt 93, register 94, digital control generator 54) and for the carrier frequency error (subtractor 95, digital filter 93, register 94, multifunction generator 5 and frequency-code correlator 4). The third and fourth outputs of the parameter estimation unit 92 are connected respectively to the first and second inputs of the digital filter 96, thereby providing loops for the code delay and a code delay error by connecting to the second input of the register 94, the output of the frequency-code correlator 4 connected to the input of the block 54 .

 In FIG. 12 is a graphical interpretation of the code phase estimate from three envelopes.

для определения псевдодальности от потребителя к i-ому КА.In FIG. 13 gives a graphical interpretation of the accumulation of the Doppler shift, which subsequently must be compensated by counter-rotation of the vector

to determine the pseudorange from the consumer to the i-th spacecraft.

реализованная на основе ПЗУ 53 частотно-кодового коррелятора 4.On Fig presents a structural diagram of the calculation of the phase of the vector of counter-rotation

implemented on the basis of ROM 53 frequency-code correlator 4.

The claimed device operates as follows. At the input of the antenna 1 of the receiver 2 of the satellite radio navigation systems of the receiver, signals from the spacecraft of two satellite radio navigation systems, namely, Glonass and Navstar Si, which are emitted in the L ₁ band and have the form
Si • L ₁ (t) Pi (t) • Di (t) • Cos (ω ₁ • L ₁ • t + Φ _i • L ₁ (1)
where Pi (t) PSP envelope of the i-th spacecraft, i = 1, n;
Di (t) navigation message of the i-th spacecraft;
Φ _i • L ₁ initial phases of the received signals;
ω _i • L ₁ carrier frequencies of the i-th spacecraft,
t current time.

 The frequency response of the receive path is determined by the frequency spectra of the received signals. The signal spectrum of the spacecraft system Navstar according to the general-use C / A code is (1575.42-1) MHz, and the signal spectrum of the spacecraft SRNS Glonass when working according to the general-use code CA and high-precision R-code is (1602.1620.6) MHz This means that the total frequency band of the received signals is 1574.42≅Δf≅1620.6 MHz, i.e. The occupied frequency band Δf is approximately 50 MHz.

 The received signals pass through the antenna and the input feeder, which is part of the antenna and is a 1/4-wave segment of the coaxial line closed on one side and serves to coordinate the parameters of the antenna and the input circuits of the receiver. From the output of the feeder antenna 1, the signals are fed to the input of a broadband filter preselector 21, which serves to limit the frequency band of the received signals in the range of 1574.42.1621 MHz. The specified filter, made on microwave lines, implements a 5th order elliptical Cauer bandpass filter. Figure 5 a presents the amplitude-frequency characteristic of this filter, and figure 5 b its phase-frequency characteristic. As can be seen from Fig.5b, the broadband filter preselector 31 has an important advantage, namely, an almost linear phase in the passband of the filter, which is a great advantage when working with complex phase-shifted signals received from satellites. This leads, for example, to the fact that the filter preselector 21 has the same linear group delay time τ in the passband equal to about 2.5 ns (Fig. 5 c). Such an implementation leads to the fact that there is no need to use a special calibrator to ensure the same group delay time t for all signals received from the spacecraft. From the output of the filter preselector 21, the signal is fed to the input of a low-noise amplifier 22, the output of which is connected to the input of a band-pass filter 23, the output signal of which is fed to the input of a second low-noise amplifier 24. The band-pass filter 23 serves to eliminate additional ripples in the obstacle band of the broadband filter-preselector 21, as well as for isolation between low-noise amplifiers 22 and 24. The main amplification of the receiving path is provided by low-noise amplifiers 22 and 24, which are made on the basis of gallium arsenide transistors moat with a schottky barrier. The parameters of low-noise amplifiers 22 and 24, a gain of 35 dB, a range of received frequencies of 1.8 GHz with uneven amplitude-frequency characteristics of 1 dB and a noise figure of 1.1 dB.

In the future, the signal from the output of the LNA 24 is fed to the input of the mixer 25, made according to the balanced circuit and representing a linear frequency shift converter, i.e. at the output of block 25, the difference frequency signal f _pr = f _c -f _{g is} extracted _, and the linearity of the group delay time t for all received signals is preserved.

The output of the mixer 25 is connected to the input of the band-pass filter 27, the amplitude-frequency characteristic of which is presented in Fig.6. It consists of two third-order Bessel filters in series with a linear phase-frequency characteristic tuned to the frequencies of the signals of the spacecraft of the Navstar system, i.e. on the frequency (133-137 MHz) and the Glonass system, i.e. frequency (157-181 MHz), thereby providing processing of input information in a wide frequency band. The output of the bandpass filter 27 is connected to the first input of the intermediate frequency amplifier 28 to further amplify the input signal. To ensure the constancy of the gain within the specified limits, an automatic gain control unit 30 is used, covering the LNA 22 and 24 of the intermediate frequency amplifier 28. The output signal of the intermediate frequency amplifier 28 is fed to the input of an analog-to-digital converter 29, in which quadrature processing of the input information is implemented by supplying to the control inputs of this node rectangular pulses with a frequency of 90 MHz with a quarter-period shift, while at the outputs I ₁ , I ₂ , a sine is formed, and at the outputs Q ₁ , Q _{2, the} cosine component of the input complex information signal.

 Further operation of the receiver-indicator is supported by internal mathematical support (MO). After passing the test programs and confirming the operability of the main nodes, the transceiver goes into interrupt standby mode, for example, from the multifunction generator 5 or from the block for solving the navigation problem.

The next problem, which is solved with the support of internal mathematical support, is the choice of the optimal working spacecraft constellation from the total number of radio-visible at a given time. The initial selection of the working constellation of the spacecraft is made according to the current almanacs of two systems that are stored in the inventive device: for the Glonass spacecraft system in RPZU 15 (figure 1), and for the Navstar system in non-volatile RAM 18 (figure 1). In this case, the approximate coordinates of the consumer’s place and the current time of the day, which are entered from the keyboard, are also taken into account. In this case, the unit for solving the navigation problem recalculates the current almanac at the current time in order to determine the radio visibility of each spacecraft at a particular time. If the almanac is outdated, or when the inventive device is turned on for the first time, the internal MO (mathematical support) issues the command "update the almanac" or "search for the spacecraft blindly." In this case, a sequential search is carried out on N-physical channels in the general case for one spacecraft of the Glonass and Navstar systems, and a navigation message is read. At the same time, ephemeral information is determined, i.e. the number of operating satellites of the two systems at a given time, their coordinates and the predicted Doppler shift relative to the consumer are determined. It should be noted that this procedure takes tens of minutes in time. In the case of using ephemeral information according to the almanac, the results of the first measurement of the state vector of the navigation parameters can be obtained in some cases with a rather large error. Knowing these initial data, the sign of SRNS K _{i is} initially formed i.e. if, for example, in the i-th channel signal is received system "Navstar" then K _i = 0 and K _i = 1 if the i-th channel signal is received from the satellite system "Glonass".

 Subsequently, from all the satellites currently operating at a given time, the optimal spacecraft constellation of the two systems is selected (for example, based on the criterion of the minimum geometric factor), while the true position of each of the satellites included in the optimal constellation is known. Since in the claimed device the number of physical channels is N = 8, then the 8 constellation of the Glonass and Navstar systems is included in the optimal constellation. Since all the physical channels of the primary processing of information are identical, let us consider in detail the operation of one of them using the example of the operation of the spacecraft of the Glonass system. This choice is explained only by the fact that the reception and processing of signals by the Glonass system is carried out according to two codes, while in the case of using the Navstar system only by the general application code, i.e. The operating principle of the GLONASS spacecraft system is more general.

I раньше,

I норма,

I позже,

Q раньше,

Q норма,

Q позже. Накопленные суммы проходят последовательно через мультиплексоры 77, 78 блок ключей 83 на блок 92 оценки параметров цифрового процессора 7 обработки сигналов.Upon receipt of a control signal from the output of the spacecraft number decoder, the operation of the tracking channel and measuring the signal parameters of this spacecraft is initialized. The receiver indicator in this case works as follows: the calculating unit 7 resets the counters 60-63 and 73 and 76, the block 7 allows the interruption of the multifunction generator 5, from the output of which 90 to the input of the multiplying device 55 of the frequency-code correlator 4 are received PSP sequences of the common code applications C earlier, C norm, C later on the second input of the device 55, in this case, read the phase readings from the ROM 53. The outputs of the multiplier 55 are connected to the accumulating adders 56-59, the outputs of which are connected to the inputs of the binary counter in 60-63 connected via binary inputs with keys 64-67 meters drives 68-71, the output of which timesharing six values are accumulated sums

I used to be

I norm

I later

Q before

Q is the norm

Q later. The accumulated amounts pass sequentially through the multiplexers 77, 78 block of keys 83 to block 92 evaluation of the parameters of the digital processor 7 signal processing.

можно получить оценки фазы кода ПСП последовательности входного сигнала
(I₁, Q₁ соответствует ψ₁
(I₁,Q₂)-ψ₂+π
(I₃,Q₃)-ψ₁+2π
По трем комплексным отсчетам соответствующие значения огибающих вычисляются в блоке 92 так

(2)
Используя значения трех комплексных огибающих, можно получить общую огибающую с помощью следующего аналитического выражения

(3)
Из рассчитанных огибающих Е₁, E₂, E₃ выбираем наибольшую, к примеру, как показано на фиг. 12, это Е₂. Затем в блоке 92 определяется максимальная амплитуда из двух соседних значений, на фиг.12 это Е₁. Это означает, что сигналы Е₁ и Е₂ определяют концевые точки для поиска максимума амплитудного значения огибающей комплексного сигнала. Используя метод деления пополам, определяем значение ψ_пик, которое удовлетворяет условию ψ₁≅ ψ_пик≅ ψ₂.Having received, for example, three complex readings of the indicated amounts

it is possible to obtain estimates of the phase of the code code of the input signal sequence
(I ₁ , Q ₁ corresponds to ψ ₁
(I ₁ , Q ₂ ) -ψ ₂ + π
(I ₃ , Q ₃ ) -ψ ₁ + 2π
For three complex samples, the corresponding values of the envelopes are calculated in block 92 so

(2)
Using the values of the three complex envelopes, one can obtain the general envelope using the following analytical expression

(3)
From the calculated envelopes E ₁ , E ₂ , E _3, choose the largest, for example, as shown in FIG. 12, this is E ₂ . Then, in block 92, the maximum amplitude is determined from two adjacent values, in FIG. 12 it is E ₁ . This means that the signals E ₁ and E ₂ determine the end points to search for the maximum amplitude value of the envelope of the complex signal. Using the method of halving, we determine the value of ψ _peak , which satisfies the condition ψ ₁ ≅ ψ _peak ≅ ψ ₂ .

(4)

Тогда оценка сдвига фаз

с целью выхода на пик взаимнокорреляционной функции выглядит так

(5)
На основании полученной оценки происходит выдача команды в блок 87 управления ПСП многофункционального генератора 5 с целью сдвига в сторону увеличения/уменьшения сдвига ПСП для минимизации сдвига фаз и выхода на пик взаимно-корреляционной функции между огибающей принимаемого сигнала и местной ПСП. Данная задача решается с помощью контура слежения, состоящего из блоков: регистра 94, частотно-кодового коррелятора 4, блока 6 интеграторов, блока 92 оценки параметров, находящегося в составе блока 7 вычислении и цифрового фильтра 96 третьего порядка (фиг.11). Второй контур слежения за ошибкой по задержке кода собран на основе тех же блоков, однако в этом случае в блоке 92 вычисляется ошибка по задержке кода на основе аналитического выражения

(6)
Из выражения (6), видно, что в случае отсутствия ошибки, т.е. совпадения местной ПСП с ПСП, входящей в состав сигнала КА, числитель его равен нулю, что подтверждает выход на максимум взаимно-корреляционной функции между огибающей принимаемого сигнала и местной ПСП.Based on FIG. 11, it can be stated that ψ at the point j _peak is the best estimate of the code phase, the relative position of the code phase is determined by subtracting the phase peak from ψ ₂ i.e. ψ _rel = ψ ₂ -ψ _peak
The code phase shift estimate for I (ψ = ψ _peak ), Q (ψ = ψ _peak ) is defined as follows:

(4)

Then the phase shift estimate

in order to reach the peak of the cross-correlation function, it looks like this

(5)
Based on the obtained estimate, a command is issued to the PSP control unit 87 of the multifunction generator 5 with the aim of shifting to increase / decrease the shift of the SRP to minimize phase shift and reaching the peak of the cross-correlation function between the envelope of the received signal and the local SRP. This problem is solved by using a tracking loop, consisting of blocks: register 94, frequency-code correlator 4, integrator block 6, parameter estimation block 92, which is part of the calculation block 7 and a third-order digital filter 96 (Fig. 11). The second code delay error tracking loop is assembled on the basis of the same blocks, however, in this case, in block 92, the code delay error is calculated based on the analytical expression

(6)
From the expression (6), it is seen that in the absence of an error, i.e. if the local PSP coincides with the PSP that is part of the spacecraft signal, its numerator is zero, which confirms the maximum cross-correlation function between the envelope of the received signal and the local PSP.

In-phase and quadrature samples coinciding with the correlation peak are used to generate an error signal of the carrier phase tracking loop using an arctangent type phase detector based on ROM 82. In addition to ROM 82, the loop includes a control unit 80, a second-order digital filter 93, register 94, frequency-code correlator 4, integrator unit 6, parameter estimation unit 92. The retention band of such a loop is approximately 20 Hz. Such a narrow band, necessary to ensure the required accuracy of tracking the phase of the carrier, has a significant drawback, since in the case of high dynamic loads of the receiver equipment or in difficult jamming conditions, a delay band of 20 Hz can occur. In order to eliminate this drawback, the inventive device introduced a frequency error tracking loop, which includes, in addition to the blocks of the carrier phase tracking loop, a subtractor 96, which calculates the difference between the angles of the measured phase of the carrier ΔΦ = Φ _{n + 1} -Φ _n providing thereby tracking the carrier frequency error. The loop holding band is 250 Hz, which increases the accuracy of measurements and the reliability of the inventive device, especially in the above-mentioned difficult operating conditions of the receiver.

Аппаратно данная реализация выполнена в ПЗУ 53 частотно-кодового коррелятора 4 (фиг.14). В ПЗУ 53 хранятся соответствующим образом рассчитанные дискретные значения фазы обрабатываемого сигнала, при этом угол антивращения ωмт реализуется с помощью цифрой управляемого генератора 54 и представлен М-битными словами.Note that the measured value of the carrier ω _i differs by the magnitude of the Doppler shift Ω, which is formed due to the mutual movement relative to each other of the spacecraft and the inventive transceiver. In the process of accumulation of samples I and Q of the received signal, the value of the Doppler phase shift also tends to accumulate (Fig.13). To compensate for the effect of phase rotation in the tracking phase of the carrier phase, the accumulated Doppler shift vector must be compensated, i.e. must be multiplied by a vector rotated in the opposite direction (antivector) in the plane I, jQ. Similarly, this operation can be represented as

Hardware this implementation is made in ROM 53 of the frequency-code correlator 4 (Fig.14). The ROM 53 stores appropriately calculated discrete phase values of the processed signal, while the anti-rotation angle ωmt is realized using the digit of the controlled generator 54 and is represented by M-bit words.

 Thus, when the digitally tuned generator 54 of the frequency-code correlator 4 and the PSP generator of the multifunction generator 5 are tuned to the frequency and envelope of the signal of the selected spacecraft, respectively, and when the time position of the PSP and the envelope Pi (t) coincide within the main lobe of the cross-correlation function, the output of block 92 produces a narrowband signal Si (t) of the selected spacecraft with a restored carrier and compensated Doppler shift.

Si (t) = Di (t) • cos (ω _i t + Φ _i ) (7)
where: Di (t) navigation message.

(мгновенное состояние дискретной фазы в петле слежения за задержкой соответствует псевдодальности а мгновенное состояние фазы в петле слежения за несущей псевдоскорости) поступают через двухпортовое коммуникационное ОЗУ 8 в блок 11 решения навигационной задачи, где происходи дешифрация навигационного сообщения Di(t) причем программно реализованные дешифраторы навигационных сообщений КА систем "Глонасс" и "Навстар" индивидуальные для каждого вида спутников, так как структура навигационного сообщения указанных СРНС отличается друг от друга.From the output of block 92, the signal Si (t) pseudorange ρ to the N-th spacecraft, pseudo-velocity

(the instantaneous state of the discrete phase in the tracking loop of the delay corresponds to the pseudorange and the instantaneous state of the phase in the loop of tracking the carrier of the pseudo-speed) is received via the dual-port communication RAM 8 to the block 11 for solving the navigation problem, where the decoding of the navigation message Di (t) takes place, and the software implemented navigation decryptors Messages of the spacecraft of the Glonass and Navstar systems are individual for each type of satellite, since the structure of the navigation message of the indicated SRNS differs from others ha.

 It should be noted that the general application codes of the GLONASS system PTs and high-precision codes are tied to the same time with an error of Dt = 5 ns; therefore, the PT signal serves as a key for accelerated synchronization with the BT code. This means that the initial synchronization is carried out according to the code of general application of PT to a special keyword, which is contained in the navigation message and the distance to which is known from its structure, after which accelerated entry into synchronism by BT code is carried out. The structure and principle of operation of tracking meters does not change.

 Work with the spacecraft of the Navstar system is carried out only by the C / A code, while the accuracy of navigation measurements is reduced and the development of special models of the propagation of radio waves to account for the ionospheric and tropospheric delays of the received signals is required.

(9)
где ρ_i измеренная псевдодальность до i-го КА;
n размерность вектора состояния потребителя;
c скорость света,

1, если i-ый КА принадлежит СРНС "Глонасс",
х вектор состояния без учета относительно временного сдвига СРНС.Since spacecraft of various systems are usually located in the working constellation, it is necessary first of all to determine the magnitude of the shift in the system time scale of the Navstar satellites relative to the Glonass SRNS time scale and only after this the current consumer state vector. For this purpose, in blocks 11 and 12, the equation of measurements of the form

(9)
where ρ _i measured pseudorange to the i-th spacecraft;
n dimension of the consumer state vector;
c is the speed of light

1, if the i-th spacecraft belongs to the Glonass SRNS,
x state vector without regard to the time shift of the SRNS.

10
где ρ_m вектор измерений псевдодальностей,
δ_m вектор признаков принадлежности КА к данной СРНС.Then the system of measurement equations for the case of work on the constellation, including the spacecraft of two different systems, has the form:

ten
where ρ _{m is the} vector of measurements of pseudorange,
δ _{m is the} vector of signs of spacecraft belonging to this SRNS.

 Having solved this system of equations, we obtain the exact value of the time shift Δτ of the time scale of the GLONASS SRNS relative to the Navstar SRNS.

(11)
где C скорость распространения сигнала;
ρ_i псевдодальность до i-го КА;
Xi, Yi, Zi известные из навигационного сообщения Di(t) координаты, КА;

известные из навигационного сообщения Di(t) скорости КА;

неизвестные координаты и составляющие вектора скорости объекта;
ω_oi номинальная частота несущей i-го КА, постоянная величина;
ω_i измеренная частота несущей i-го КА;

расстройка частоты опорного генератора ПИ относительно опорного генератора РСНС;
Δτ временное рассогласование между шкалами времени СРНС двух систем,
Решив данную систему уравнений для случая, когда число наблюдаемых СРНС не менее 4, получим результирующий вектор состояния объекта

(12)
который выводится на индикатор 20. Среднеквадратичная ошибка G оценки координат и времени равна

(13)
где σ_x, σ_y, σ_z, σ_t среднеквадратичная ошибка по трем координатам и времени,
σρ cреднеквадратичная ошибка измерения псевдодальностей;
M геометрический фактор.Subsequently, in block 11, the following system of equations is solved using one of the methods for optimal estimation of the state vector, for example, the least squares method

(eleven)
where C is the signal propagation speed;
ρ _i pseudorange to the i-th spacecraft;
Xi, Yi, Zi coordinates known from the navigation message Di (t), spacecraft;

spacecraft speeds known from the navigation message Di (t);

unknown coordinates and components of the object's velocity vector;
ω _{oi is the} nominal carrier frequency of the i-th spacecraft, constant;
ω _i measured carrier frequency of the i-th spacecraft;

detuning the frequency of the reference PI generator relative to the reference RSNS generator;
Δτ is the temporary mismatch between the SRNS time scales of the two systems,
Having solved this system of equations for the case when the number of observed SRNSs is at least 4, we obtain the resulting state vector of the object

(12)
which is displayed on indicator 20. The standard error of the coordinate and time estimates G is

(thirteen)
where σ _x , σ _y , σ _z , σ _{t the} mean square error in three coordinates and time,
σρ is the standard error of the measurement of pseudorange;
M is a geometric factor.

Compared with the device prototype 3 in the inventive device achieved the following advantages:
a) the possibility of receiving and processing signals of two SRNS of two systems "Glonass" and "Navstar" using one receiving path, i.e. without resorting to multiplexing or duplication of the reception channels, thereby achieving a significant simplification of the receiving equipment,
b) the implementation of the receiver is carried out using one conversion to an intermediate frequency with the aim of further digital processing of signals received from the spacecraft in a wide frequency band, in this case there is no additional interference to the mirror channel, which have a meso in double frequency conversion. The supply of local oscillator signals, an analog-to-digital converter, as well as clock frequencies of 90 MHz, 20 MHz, 12 MHz to ensure the operability of the digital part of the transceiver occurs using a single frequency synthesizer. The use of a pulsed phase and frequency detectors in the frequency synthesizer protects the device from false captures at multiple frequencies of a voltage-controlled generator and thereby ensures high reliability and accuracy of the circuit,
c) the inventive device provides higher accuracy of reproducing input information through the use of filters with elliptic approximation and linear frequency conversion, which allows to obtain a linear phase-frequency characteristic of the receive path, and, as a result, the same and minimum group delay time for all received spacecraft signals . In this case, there is no need to use a special calibrator for averaging the group delay time.

d) higher accuracy of measurements and operational reliability due to the introduction of additional tracking loops due to carrier frequency error, code delay and code shift, which ensures reliable operation when tracking is disrupted by the code or carrier, for example, in the case of intentional interference or during installation receiver indicator on highly dynamic objects,
e) the use of the two radio navigation systems Glonass and Navstar to determine the vector of measured parameters of spacecraft makes it possible to measure the state vector of parameters of consumer equipment at any time of the day, even if one of the systems is not fully deployed or some satellites fail,
f) the inventive device due to the multi-channel organization of the computational measurement process ensures operability in the conditions of partial shadowing of the spacecraft (for example, on city streets with high-rise buildings or deciduous forest, when there is a multipath factor).

 Thus, the tasks set for the invention are fulfilled. Tsa

Claims (2)

 1. The receiver indicator of satellite radio navigation systems, comprising an antenna, a receiver, the synchronization input of which is connected to the output of the reference thermostatic generator, a pseudorange and pseudo-speed calculation unit, an interface unit, a navigation task solution unit, a spacecraft constellation selection unit, random access memory, read-only memory characterized in that the N-channel block for primary processing of information, the first and second blocks according signal levels of the communication line, input / output unit for navigation parameters, a second random access memory, a second read-only memory, a programmable read-only memory, a timer and an indicator, the antenna output is connected to the input of the receiver, the information output of which is connected to the information inputs of the N-channels of the unit primary information processing, each channel containing a frequency-code correlator, a block of integrators and a multifunctional pseudo-random message generator Sequences, the information output of the receiver is connected to the first information inputs of the frequency-code correlators of the N channels of the primary information processing unit, the outputs of which are connected to the information inputs of the integrator block, the outputs of which are connected to the data bus of the pseudo-range and pseudo-speed calculation unit, whose bi-directional control bus is connected respectively to the control inputs multifunctional pseudo-random sequence generators, frequency-code correlators and integ blocks speakers, the information outputs of the multifunctional pseudorandom sequence generators of each channel of the primary information processing unit are connected respectively to the second information inputs of the frequency-code correlators, the information output of the pseudorange and pseudo-speed calculation unit is connected to the first input of the interface unit, the output of which is connected to the first input of the first signal level matching unit communication line connected by the output to the first input of the second block matching ur of the signals of the communication line connected to the information input of the block for solving the navigation problem, the output of which is connected to the information input of the block for selecting the working constellation of spacecraft, the output of which is connected simultaneously with the information inputs of the first read-only memory, the first random access memory and programmable read-only memory, the second bidirectional input of the first block matching signal levels of the communication line is connected to the information input of the input / output unit of the navigation parameters, the first bi-directional output of which is connected simultaneously with the timer, the second random access memory and the second permanent memory device, the information output of the input / output unit of the navigation parameters is connected to the indicator, the first output of the receiver clock synchronization is connected to the clock inputs synchronization of frequency-code correlators, integrator blocks, multi-function pseudo-random sequence generators N channels of the primary information processing unit and the pseudorange and pseudo-speed calculation unit, the second output of the receiver clock synchronization is connected to the clock synchronization inputs of the first and second blocks of signal level matching of the communication trunk, the block for solving the navigation problem and the block for selecting the working constellation of the spacecraft receiver-indicator of satellite radio navigation systems.  2. The receiving indicator according to claim 1, characterized in that the receiver comprises a mixer, first and second low-noise amplifiers, an intermediate frequency amplifier, an analog-to-digital converter, a reference frequency synthesizer, a broadband filter preselector, first and second bandpass filters, an automatic gain control unit , the input of the broadband filter preselector is connected to the output of the antenna feeder, and the output to the first input of the first low-noise amplifier, the output of which is connected to the input of the first band-pass filter, the output of which is connected with the first input of the second low-noise amplifier, the output of which is connected to the first input of the mixer, the output of which is connected to the input of the second band-pass filter, the output of which is connected to the input of the intermediate frequency amplifier, the output of which is connected simultaneously to the information input of the analog-to-digital converter and the input of the automatic gain control unit , the output of the automatic gain control unit is connected simultaneously with the second input of the first low-noise amplifier, the second input of the second low-noise amplifier amplifier and the second input of the intermediate frequency amplifier, the input of the frequency synthesizer is the input of the receiver synchronization, the first output of the frequency synthesizer is connected to the second input of the mixer, the second and third outputs of the frequency synthesizer are connected respectively to the first and second control inputs of the analog-to-digital converter of the receiver, the fourth output of the frequency synthesizer connected simultaneously to the clock inputs of the frequency-code correlators, integrator blocks, multi-function pseudorandom generators sequences of N channels of the primary information processing unit and to the clock synchronization input of the pseudo-range and pseudo-speed calculation unit, the fifth output of the frequency synthesizer is connected simultaneously with the clock synchronization inputs of the first and second blocks of signal level matching of the communication trunk, the block for solving the navigation problem, and the block for selecting the working constellation of the spacecraft of the receiver indicator .

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