RU2079148C1 - Multichannel receiver indicator of satellite radionavigational systems - Google Patents

Abstract

FIELD: satellite navigation for determining the vector of condition of users according to the signals of two mutually asynchronized systems. SUBSTANCE: receiver indicator uses antenna 1, receiver 2, reference generator 3, single-channel primary data processing unit, having pseudorandom sequence generator 5, frequency-code correlator 4, integrator unit 6 and radionavigational parameters measurement unit 7, interface unit 8, communication line signal level matching unit 9, navigational parameters vector determining unit 10, two internal storages 11, two permanent storages 12, 16, input-output unit 13, timer 14, indicator 17. EFFECT: enhanced reliability. 2 cl, 16 dwg

Description

 The 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 preamplifier outputs are connected respectively to the first and second inputs of the frequency converter. The outputs of this converter, in turn, are connected respectively to the inputs of the first fourth channels of 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 four satellites in time-sharing mode. The outputs of the first fourth carrier tracking channels and the output of the code delay tracking channel are connected to the corresponding inputs of the control processor. The output of the control processor is connected to the input of the communications unit, the first output of which is connected to the input of the navigation processor, and the second to the input of the control and display unit. The specified receiver-indicator / 1 / also contains a reference thermostated generator and a frequency synthesizer.

 The disadvantage of this device / 1 / is the impossibility of working 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 satellites only the "Navstar" system, which limits the possibility of high-precision continuous navigation measurements, especially when the spacecraft of the specified system is not fully deployed).

In addition, the receiver-indicator / 1 / provides low accuracy in measuring the state vector of navigation parameters, for example, in the code delay tracking channel of a given device, the code delay of the first channel tracking delay code with a frequency of L ₁ is measured first, then the second delay tracking channel code with a frequency of L ₁ , etc. those. the device / 1 / does not ensure the continuity of radio navigation measurements, which leads to a decrease in the accuracy of navigation measurements of the consumer's state vector, especially when installing a receiver indicator on highly dynamic objects.

These shortcomings 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 a synthesizer, a digital correlator, a control device, a code generator, the first digital generator controlled by a digital code (GCC), intended for control a code generator, a 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 measurements of quasidality with time stamps, the third data of measurements of the rate of change of range. 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 block 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 are fed 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 units. 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 uncertainty time frequency and, as a result, reduce the time it takes to receive the first reference, as well as reduce the overall dimensions and power consumption.

 However, the receiver indicator / 2 / has a number of serious disadvantages. First, the device / 2 / operates on the spacecraft signals of the Navstar system only, 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 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 receiver including a module of a two-channel pre-amplifier, outputs which are connected respectively to the first and second inputs of the radio frequency switch; RF signal converter with lowering the range of operating frequencies, frequency synthesizer, adaptive analog-to-digital converter (ADC). The device / 2 / also contains a digital correlator mixer, a pseudo-random sequence generator (PSP), a PSP generator control unit, a digital code controlled generator, a digital carrier frequency generator, a digital signal processing processor, a communication interface, a navigation processor, a floating point coprocessor, Random-access RAM, read-only memory and a thermostatically controlled oscillator.

 The advantage of the prototype device is the modular organization of the constituent parts of the receiver-indicator, which allows implementing the multi-channel principle of constructing consumer equipment (AP) and thereby ensuring the required measurement accuracy 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 has a number of significant drawbacks that worsen its technical characteristics. So, for example, the receiver-indicator provides work only with the signals of the Navar STAR satellite navigation system, which leads to a decrease in the accuracy of measuring the vector of navigation parameters, especially when the systems are not fully deployed or when 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 contains in each receive channel only two tracking rings (for the carrier frequency and code), 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 complex jamming conditions, and in some cases and 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 spacecraft signal reception channel 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;
improving the accuracy of measurements of the consumer state vector by reducing the group delay time of the received signals of the GLONASS and Navstar SRNS;
improving the accuracy, noise immunity and reliability of the inventive receiver indicator due to the introduction of additional circuits for auto tracking on the carrier frequency and code, as well as automatic narrowing of the tracking band.

 These advantages over the prototype device are achieved due to the fact that the receiver-indicator of satellite radio navigation systems, containing an antenna, a receiver, the synchronization input of which is connected to the output of the reference thermostatically controlled oscillator, a frequency-code correlator, a digital signal processing processor, a communication interface, a navigation microprocessor, RAM , ROM additionally introduced an N-channel block of primary information processing, a trunk adapter, an input-output processor, non-volatile RAM, a second ROM, a time and an indicator. The antenna input is connected to the input of the receiver, the output of which is connected to the information input of the first N-th block of the primary processing of information of the transceiver. Moreover, each channel contains its own frequency-code correlator, a block of integrals and a multifunction generator; the first information inputs of the frequency-code correlators are connected to the information output of the receiver, the outputs of the frequency-code correlators are connected to the information inputs of the integrator blocks, the outputs of which are connected to the data bus of the digital signal processing processor. The bi-directional control bus of this processor is connected respectively to the control inputs of the multifunction generators of the frequency-code correlators and integrator blocks, while the information outputs of the multifunction generators are connected to the corresponding second information inputs of the frequency-code correlators of the first N-th channel of the primary information processing unit. The information output of the digital signal processing processor is connected to the input of the communication interface, the output of which is connected to the first input of the trunk adapter, the output connected to the information input of the navigation microprocessor, the output of which, in turn, is connected to the information buses of the random access memory and the first read-only memory. The second bi-directional input of the adapter is connected to the input of the I / O processor, the first bi-directional output of which is connected simultaneously to a timer, non-volatile RAM and a second ROM, the second information output of the I / O processor being connected to the receiver indicator of satellite radio navigation systems.

 In the claimed device, the solution of the tasks is also achieved due to the new approach to the implementation of the receiver of input signals received from the spacecraft. So, in the signal receiver of satellite navigation systems containing an antenna, a mixer, a first low-noise amplifier, an intermediate-frequency amplifier, an analog-to-digital converter, a reference frequency driver, a broadband filter preselector, a second low-noise amplifier, a first and second band-pass filters, an automatic gain control. The output of the antenna feeder is connected to the input of a broadband filter preselector connected by the output to the first input of the first low-noise amplifier, the output of which is connected to the input of the first low-pass filter, the output connected to the first input of the second low-noise amplifier. The output of this node is connected to the first input of the mixer, the output of which is connected to the input of the second bandpass filter, connected by the output to the input of the intermediate frequency amplifier, the output of which is connected simultaneously with 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 and the second input of the intermediate frequency amplifier, while the input of the reference frequency shaper (FSOCH) is the input of the receiver synchronization, while the first output of the reference grid shaper frequency is connected to the second input of the mixer, the second and third outputs of the FSOCH are connected respectively to the first and second control inputs of the analog-to-digital converter a source of SRNS signals, the fourth output of the FSOC is connected simultaneously with the clock inputs of the frequency-code correlators of integrator blocks, multi-function generators and a digital signal processing processor, the fifth output of the reference frequency former is connected simultaneously with the clock inputs of the trunk adapter, the navigation microprocessor of the multi-channel receiver-indicator of satellite radio navigation systems .

 In FIG. 1 is a functional diagram of a multi-channel receiver indicator of satellite radio navigation systems, FIG. 2 is a functional diagram of a signal receiver of satellite radio navigation systems, FIG. 3 is a structural diagram of a reference frequency driver, and FIG. 4 is a functional diagram of a multi-stage frequency divider of a receiver reference frequency; in Fig.5 a variant of the technical implementation of the analog-to-digital converter of the receiver, in Fig.6 a functional diagram of a frequency-code correlator, in Fig.7 a functional Fig. 8 is a functional diagram of a primary processing unit for receiver signals, in Fig. 10 is a block diagram of a cyclic search algorithm for spacecraft signals, in Fig. 11 is a block diagram of a band narrowing algorithm for tracking with reduced accuracy SRP for the Glonass system (Navstarstar C / A), Fig. 12 is a block diagram of the reduced accuracy tracking algorithm for SRP of the Glonass system, Fig. 13 is a flowchart of a signal tracking failure analysis algorithm KA, on Fig.14 presents a block diagram of the tracking algorithm for the high-precision SRP of the Glonass system, Fig. 15 is a graphical interpretation of the formation of the Doppler shift of the received signal from the SRNS spacecraft; FIG. 16 shows a diagram of the formation of the Doppler shift compensation vector.

 According to the invention, the receiver-indicator of satellite radio navigation systems (FIG. 1) comprises an antenna 1 with an input feeder, an output connected to the input of a receiver 2, which provides simultaneous processing in a wide frequency band of the spacecraft signals of the Glonass and Navstar systems. The reference thermostatically controlled oscillator 3 produces a reference of 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 converting the reference frequency, 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 from 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 digital signal processing processor 7, performs a number of functions 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 communication interface 8 serves to exchange information between the digital signal processing processor 7 and the navigation processor unit, including the main adapter 9, the navigation microprocessor 10, as well as the necessary elements of the organization of the computing process for solving the navigation problem, namely RAM and ROM 12.

 The results of solving the navigation problem are fed to the input of the input-output processor 13, for the functional support of which the timer 14, non-volatile random access memory 15 and ROM 16 are used. The measurement results of the vector of navigation parameters are sent to indicator 17.

 The receiver 2 signals of satellite radio navigation systems (Fig. 1,2) contains a broadband filter preselector 18, the input of which receives a signal from the output of the feeder antenna 1. The output of the broadband filter preselector 18 is connected to the first input of the first low-noise amplifier 19, connected, in turn, the output with the input of the bandpass filter 20, the output of which is connected to the first input of the second low-noise amplifier 21. The output of the low-noise amplifier 21 is connected to the input of the mixer 22, the second output of which is connected to the second input The holder 23 of the grid of reference frequencies, which in this case acts as a local oscillator. The input of the shaper 23 of the reference frequency grid is connected to the output of the reference thermostatic generator 3. The output of the mixer 22 is connected to the input of the bandpass filter 24, which provides the signals of the spacecraft SRNS Glonass and Navstar at the differential intermediate frequency, the output of the bandpass filter 24 is connected to the first input amplifier 25 intermediate frequency. The output of the intermediate frequency amplifier 25 is connected simultaneously with the input of the analog-to-digital converter 26, the output of which is the digital output of the receiver 2, as well as with the input of the automatic gain control unit 27. The output of the latter is connected to the second input of the intermediate frequency amplifier 25; the second input of the second low-noise amplifier 21 and the second input of the first low-noise amplifier 19. The second and third outputs of the reference frequency driver 23 are connected by a quarter-period offset relative to each other, thereby providing the formation of a quadrature and in-phase component at the output of the ADC 26.

 The generator 23 of the reference frequency grid (Fig. 2, 3) includes a pulse-phase detector 28, the first input of which receives a signal from the output of the thermostated generator 3. The output signal from the output of the thermostated generator 3 also goes to the first input of the frequency detector 29. Output pulse-phase detector 28 and frequency detector 29 are connected respectively to the first and second inputs of the adder 30, the output connected to the input of the low-pass filter 31 (low-pass filter). The output of the low-pass filter 31 is connected to the input of a voltage controlled oscillator (VCO) 32, the output of which, in turn, is connected to the input of the mixer 22, thereby providing a 1440 MHz local oscillator signal, as well as to the input of a multi-stage frequency divider 33, thereby forming a grid of reference frequencies necessary for the operation of microprocessors and other digital circuits.

 The multi-stage frequency divider 33 (Fig. 3, 4) contains a T-trigger 34, the clock input of which is connected to the output of the voltage controlled oscillator 32, and is the input of the multi-stage frequency divider 33. The direct output T of the trigger 34 is connected to the clock input T of the trigger 35, and the inverse to the counter input of the divider 36, 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; from the second output, a sequence of rectangular pulses with a frequency of 12 MHz is taken, which is fed to the input of the clock frequency of blocks 9, 10, 13; the third output of the specified counter is connected respectively to the second inputs of the pulse phase detector 28 and the frequency detector 29.

 The inverse output of the trigger 35 is connected simultaneously with the input T of the trigger 37 and the first input of the 3-I 38 element. The output T of the trigger 37 is connected simultaneously to the input of the T-trigger 39 and the second input of the 3-I 38. The output of the T-trigger 39 is connected simultaneously with the third the input of element 3-I and the first control input of the analog-to-digital converter 26. The direct output of the T-trigger 35 is connected to the synchronization input of the T-trigger 40, the output of which is connected to the synchronization input of the T-trigger 41, the output connected to the second control input of the analog-digital will transform A 26. The output of the 3-I 38 element is connected to the reset inputs of the T-flip-flops 40 and 41. The signals that are removed from the output of the flip-flops 39 and 41 are fed to the corresponding inputs of the analog-to-digital converter 26 with a quarter time offset relative to each other thereby providing quadrature signal processing.

The analog-to-digital Converter 26 (Fig. 2, 5) contains comparators 42, 43, 44, the first input of which receives a signal from an amplifier 25 of an intermediate frequency. The second input of the comparator 42 is connected to a positive potential that determines the threshold comparison voltage (U _por1 ); the second input of the comparator 43 is connected to a negative potential that determines the threshold comparison voltage (U _por2 ); the second input of the comparator 44 is connected to a zero potential, which also determines the threshold comparison voltage (U _por3 ); the outputs of the comparators 42, 43 are connected respectively to the first and second inputs of the OR element 45, the output of which is connected simultaneously with the information inputs of the D-flip-flops 46 and 47. The output of the comparator 44 is connected to the information inputs of the D-flip-flops 48 and 49. The clock inputs of the triggers 46 and 48 simultaneously connected to the output of the T-flip-flop 39, and the clock inputs of the D-flip-flops 47 and 49 are simultaneously connected to the input of the T-flip-flops 46 and 48 form the first (sine) pair of samples I ₁ and I ₂ , and the outputs of the D-flip-flops 47 and 49 - the second (cosine) pair of samples Q ₁ and Q ₂ output information signal.

 The frequency-code correlator 4 (Fig. 1 and Fig. 6) contains a device 50 multiplication (UP), the first fourth inputs of which receive signals from the output of the ADC 26 of the receiver, and the fifth eighth inputs of the UP 50 receive signals from the output of the generator 51 with digital control, the input of which in turn receives the calculation data from the data bus of the digital signal processing processor 7. The output of UP 50 is connected to the corresponding inputs of block 52 of logical multiplication, while the second inputs of this device receive the values of pseudo-random sequences from the output of multifunction generator 5. The results of logical multiplication are fed to the inputs of accumulating adders 53, 54, 55, 56, 57, and 58. Pulse the outputs of the six accumulating adders listed above are connected to the clock inputs of the binary counters 59, 60, 61, 62, 63 and 64. The reset outputs of these counters are interconnected and connected to the reset control output digital processor 7 signal processing.

 Block 6 integrators (Fig. 1 and Fig. 7) contains N-adequate channels, each of which includes on-off keys 65 70, the first inputs of which receive signals I normal, Q normal, I earlier, I later, Q earlier, Q later, from the outputs of the binary counters 59 64 of the frequency-code correlator 4. The second inputs of the on-off keys 65 70 receive information from the output of the digital signal processing processor 7; the choice of the operating mode is carried out by supplying the control potential from the control bus of the digital processor 7. The outputs of these on-off keys are connected to the clock inputs of the drive counters 71 76, respectively. The installation outputs of these drive counters are interconnected and connected to the first output of the control unit 77, 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 the registers 78 83, the clock inputs of which are interconnected and connected to the second output of the control unit 77. The outputs of these registers are connected to the information inputs of the multiplexer 84, the control inputs of which receive signals from the third eighth outputs of the control unit 77. The outputs of the first N-th channel of the block 6 integrators are connected to the information inputs of the multiplexer 84, which is controlled using the node 85 priority interruptions. The output of the interface unit 86 is connected to the control input of the interface 8, and the output of the key unit 87 is connected to the data bus input of the digital signal processing processor 7.

 Multifunction generator 5 (Fig. 1 and Fig. 8) contains a frequency divider 88, the first fifth outputs of which are connected to the corresponding inputs of the generator 89 clock frequencies. The second input of the clock frequency generator 89 is supplied from the first output of the pseudo-random sequence control unit 90, the input of which is connected to the control bus of the digital signal processing processor 7. The first output of the clock frequency generator 89 is connected to the synchronization input of the low-accuracy (ПП) alternator of the Glonass system and the general-use ПС generator of the Navstar system, which are based on the ПТ / СА 91 generator. The generator operating mode is selected by connecting the second output of the PSP control unit 90 to the control input of the unit 91 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 91, and when working with the SC of the system of Navstar, it is 1.023 MHz. The second output of the clock frequency generator 89 is connected to the synchronization input of a high-precision SRP generator (VTcode), which is based on block 92. In the case of operation of block 92, a frequency signal of 5.11 MHz arrives at its synchronization input. The information output of block 92 is connected to the third output of the pseudo-random sequence control block 90, thereby providing the possibility of programmatically changing the operating mode of the PSP generator 92. The information outputs of blocks 91 and 92 are connected respectively to the first and second inputs of multiplexer 93, the first and second control inputs of which are connected respectively with the fourth and fifth outputs of block 90. At the outputs of the multiplexer 93, depending on the combination of input signals, pseudo-random sequence signals are generated her CAP "before," PSP "norm" PSP "later" Signal spacecraft systems "Glonass" and "Navstar" respectively. The control outputs of blocks 91 and 92 are connected respectively to the first and second control inputs of the pseudorange counter 94, the clock input of which is connected to the clock input of the multifunction generator 5. The information input of the pseudorange counter 94 is connected to the sixth output of the PSP control unit 90, providing the initial pseudorange vector. The information output of the specified counter 94 is connected to the data bus of the digital signal processing processor 7.

 The primary information processing section (Fig. 9) 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 95, the first output which is connected to interface 8, and the second to the programmable block 96 of the arctangent phase detector of the carrier phase tracking loop (block 36, digital filter 97, register 8, digital controlled oscillator 51) and the carrier frequency error (subtractor 99, digital oh filter 97, register 98 and digitally controlled oscillator 51). The third and fourth outputs of the parameter estimation block 95 are connected respectively to the first and second inputs of the digital filter 100, thereby ensuring the implementation of the circuits behind the code delay and the code delay error by connecting to the second input of the register 98, the output of the frequency-code correlator 4 connected to the input of the block 51.

(I', Q') для определения псевдодальности от потребителя к i-ому КА.In FIG. 10 gives a graphical interpretation of the accumulation of the Doppler shift, which should subsequently be compensated by the counter-rotation of the vector

(I ', Q') to determine the pseudorange from the consumer to the i-th spacecraft.

(I', Q'), реализованная на основе блока 52 логического умножения частотно-кодового коррелятора 4.Figure 11 presents the structural diagram of the calculation of the phase of the counter-rotation vector

(I ', Q'), implemented on the basis of block 52 of the logical multiplication of the frequency-code correlator 4.

где P_i(t) ПСП-огибающая i-го КА,
D_i(t) навигационное сообщение i-го КА,
Φ_i•L₁ начальные фазы принимаемых сигналов,
ω_i•L₁ несущие частоты i-го КА,
t текущее время.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, are received simultaneously, which are emitted in the L ₁ range and have the form

where P _i (t) PSP envelope of the i-th spacecraft,
D _i (t) navigation message of the i-th spacecraft,
Φ _i • L _{1 the} 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 ARNS Glonass when working according to the general-use code SA and high-precision P-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 quarter-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 18, 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 an elliptic band filter KAUERA 5th order.

 From the output of the filter preselector 18, the signal goes to the input of a low-noise amplifier 19, the output of which is connected to the input of a band-pass filter 20, the signal from the output of which goes to the input of a second low-noise amplifier 21. The band-pass filter 20 serves to eliminate additional ripples in the obstacle band of the broadband filter-preselector 18, as well as for isolation between low-noise amplifiers 19 and 21. The main force of the receiving path is provided by low-noise amplifiers 19 and 21, which are based on gallium arsenide transistors with a Schottky barrier. The parameters of low-noise amplifiers 19 and 21: 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 21 is fed to the input of the mixer 22, made according to the balanced scheme and representing a linear frequency shift converter, i.e. at the output of block 22, a difference frequency signal f _pr f _with f _{g is extracted} , and linearity and constancy of the group delay time τ for all received signals are maintained.

The output of the mixer 22 is connected to the input of the band-pass filter 24. It is two sequential third-order Bessel filters with a linear phase-frequency characteristic tuned to the frequencies of the signals of the spacecraft of the Navstar system, that is, to the frequency (133 137 MHz) and the system Glonass, i.e., at a frequency (157,181 MHz), thereby providing processing of input information in a wide frequency band. The output of the bandpass filter 524 is connected to the first input of the intermediate frequency amplifier 25 to further amplify the input signal. To ensure constant gain within specified limits, an automatic gain control unit 27 is used, covering the LNA 19 and 21, an intermediate frequency amplifier 25. The output signal of the intermediate frequency amplifier 25 is fed to the input of an analog-to-digital converter 26, which implements quadrature processing of the input information by supplying to the control inputs of this node of rectangular pulses with a frequency of 90 MHz with a shift by a quarter of the period, 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 a multifunction generator 5, or a block for solving a navigation problem.

The next problem, which is solved with the support of internal mathematical support, is the choice of the optimal working spacecraft creation 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 in ROM 12 (figure 1), and for the Navstar system in non-volatile RAM 15 (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, can also be 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 the first time the inventive device is turned on, internal MO (software) issues the command "update the almanac" or "search for the spacecraft blindly." In this case, a sequential search of signals is carried out on N-physical channels in the general case of one SC of the Glonass and Navstar systems, and a navigation message is read. Ephemeris information is also determined at the same time, 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. In the case of using outdated almanac information, the results of the first measurement of the state vectors of navigation parameters can be obtained with a sufficiently large error. Knowing these initial data, the sign of SRNS K _{i is} initially formed, i.e. if, for example, the signal of the Navstar system is received in the ith channel, then K _i 0 and K _i 1, if the signal from the descent of the Glonass system is received in the i-th channel.

 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 the claimed device has a physical channel number of 8, the optimal constellation includes 8 spacecraft of the Glonass and Navstar systems. Since all the physical channels of the primary processing of information are identical, let us consider the detailed operation of one of them using the example of the operation of the GLONASS spacecraft. 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, that is, the principle of operation by the Glonass spacecraft system is the most common.

Organization of the computational process of the operation of the receiver indicator is carried out using the control program manager, which is located in the navigation (system) microprocessor 10. After the procedure for selecting the optimal working constellation of the spacecraft, which are used to measure the vector of navigation parameters, the corresponding drivers for controlling the information processing channels are turned on, which communication: microprocessor 10, adapter 9 trunk, interface 8 and digital processor 7 signal processing, produce t Kim way initial transmission data packet to the first channel N-th primary data processing unit. Among them must be transmitted:
a) the command "start a cyclic search for spacecraft signals";
b) type of code PSP (PT, VT, C / A) by which the signal is searched;
c) the magnitude of the search step in frequency and pseudorange;
d) the values of the nominal carrier frequencies of the spacecraft of the Glonass and Navstar systems, as well as their numbers;
d) a priori preset value of the Doppler frequency.

A simplified flowchart of a sequential cyclic procedure for searching for a spacecraft signal in the plane of the parametric uncertainty of time — the frequency of representation in FIG. 10. Its essence consists in sequentially viewing the plane of uncertainty, which is divided into NN unit cells, accumulating the input signal module in the observation interval T _n and comparing its value with the previously calculated lower A and upper B thresholds, which are set, for example, depending on the probability false detection of a and skipping of signal b, as well as the number of elementary cells NN studied. If the accumulated value of the output signal module SUM exceeds the upper threshold B (program block 6), then a signal is detected, the sign “signal is” (program block 8) is set, and the frequency and pseudorange values are sent via interface 8 and main adapter 9 to the navigation microprocessor 10 for further processing, and the information processing channel goes into the tracking mode for the parameters of the carrier frequency and code.

 If the value of the accumulated module is less than the lower threshold A (block 7, Fig. 10), then the signal in the cell under study is absent and it is necessary to perform a frequency shift and repeat the search procedure (block 8, Fig. 10). This controls the pre-calculated number of steps L in frequency (block 10, Fig. 10) and pseudorange M (block 13, Fig. 10).

 If the injected value of the SUM module satisfies the inequality B> SUM> A, then the accumulation of the input signal continues until one of the results is obtained (“signal is”) SUM> B or “signal is not” SUM <A), and, if necessary, shift along the SRP in order to exit with a given probability to the peak of the cross-correlation function between the SRP of the input signal and the MFG of the generator 5. The spacecraft signal in the plane of a priori uncertainty occurs cyclically; the exit from the program can be forced by interruption, for example, from the manager program of the navigation microprocessor 10.

 To ensure highly reliable addition of the reduced accuracy code for the Glonass system, it is necessary to realize the possibility of narrowing the contour strip of the servo-indicator tracking system. At the same time, as calculations show, the band of the tracking loop for the phase of the SC carrier should be narrowed to 20 Hz.

The block diagram of the band narrowing algorithm is shown in FIG. 11. When implementing this mode in the program, the signal-to-noise ratio q _i is calculated, the value of which must exceed the previously calculated threshold value B (block 7, Fig. 11). Exceeding this value confirms the stable addition of the spacecraft signal. After that, the program calculates the current value of the strip of the tracking loop B, achieving its narrowing to 20 Hz (blocks 8, 10, Fig. 11). If the required width of the tracking band is provided, the subroutine "front search" of the navigation message is called up and transition to tracking along the SRP of the GLONASS system is carried out (Fig. 12).

и фазы

, которые получены в контуре слежения за несущей частотой и фазой ПСП (блок 2, фиг. 13). Если, например, в i + 1 момент восстановлен сигнал КА, причем время срыва сопровождения t_ср не больше заранее рассчитанной величины t_max (блок 4 и 6, фиг. 13), производится дальнейший поиск фронта ПСП пониженной точности "Глонасс", вычисление и анализ значения текущей полосы сопровождения (блоки 8, 10, 14 и 16 соответственно, фиг. 12), а в дальнейшем переход в режим слежения по коду высокой точности. В случае, если t_ср > t_max (блок 6, фиг. 13) подпрограмма осуществляет один из видов поиска сигнала КА, например, в полосе 250 Гц.In some cases, for example, with high dynamics of consumer movement or spacecraft shadowing, it is possible to disrupt the tracking of its signal. In this case, the signal-to-noise ratio q _{i is} less than the threshold value B (block 6, Fig. 12). In this case, the equipment switches to the mode of analysis of the breakdown of tracking (block 7, Fig. 12). The block diagram of the tracking failure analysis algorithm is shown in FIG. 13. In this case, the digital processor 7 of the signal processing captures the initial moment of failure of the tracking t _cf t _n (block 1, Fig. 13), as well as the last (before the failure) frequency values

and phases

, which are obtained in the tracking loop for the carrier frequency and the phase of the SRP (block 2, Fig. 13). If, for example, the spacecraft signal is restored at i + 1 moment, and the tracking interruption time t _{cf is} not greater than the previously calculated value t _max (block 4 and 6, Fig. 13), a further search is made for the front of the Glonass low-accuracy SRP, calculation and analysis of the value of the current tracking band (blocks 8, 10, 14 and 16, respectively, Fig. 12), and then the transition to the tracking mode by high accuracy code. If t _av > t _max (block 6, Fig. 13), the subroutine performs one of the types of search for the spacecraft signal, for example, in the band of 250 Hz.

In the case of working with the high-precision code of the Glonass system, the system (navigation) microprocessor 10 issues a command to the multifunction generator 5 to set the necessary initial data. In this case, the width of the tracking band according to the high-precision code can be fractions of a hertz. In this mode, the navigation message is also read (block 11, Fig. 14) for subsequent processing in the navigation microprocessor 10. Note that the carrier phase tracking loop (Fig. 9) is implemented on the basis of programmable block 96 (arc tangent phase detector), programmable second-order digital filter 97, register 98, frequency-code correlator 4, integrator unit 6, parameter estimation unit 95. The carrier frequency error tracking loop also includes a subtractor 99, which calculates the difference between the angles of the measured phase of the carrier Dv = Φ _{n + 1} - Φ _n , while ensuring that the carrier frequency error is monitored.

 Such an approach significantly increases the reliability and accuracy of the radio engineering measurements of the device in question, especially in the conditions of dynamic overloads, complex jamming conditions, or partial shading of spacecraft.

Аппаратно данная реализация выполнена в устройстве 50 перемножения частотно-кодового коррелятора 4 (фиг. 16), при этом угол антивращения ω•M•T реализуется с помощью генератора 51 с цифровым управлением и представлен М-битными словами.It is noteworthy 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 motion relative to each other of the spacecraft and the inventive transceiver. During the accumulation of samples I and Q of the received signal, the value of the Doppler phase shift also tends to accumulate (Fig. 15). 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 turned in the opposite direction (antivector) in the plane I, j Q. Analytically, this operation can be represented as follows:

This implementation is implemented in hardware in the device 50 for multiplying the frequency-code correlator 4 (Fig. 16), while the anti-rotation angle ω • M • T is realized using a digitally controlled generator 51 and is represented by M-bit words.

Thus, when tuning the generator 51 with digital control of the frequency-code correlator 4 and the SRP generator of the multifunction generator 5, respectively, to the frequency and envelope of the signal of the selected spacecraft and when the temporary position of the SRP with the envelope P _i (t) coincides within the main lobe of the cross-correlation functions at the output of the parameter estimation block 95, a narrow-band signal S _i (t) of the selected spacecraft with a restored carrier and compensated Doppler shift is formed
S _i (t) = D _i (t) • cos (ω _i • t + Φ _i ) (2)
where D _i (t) navigation offset.

(мгновенное состояние дискретной фазы в петле слежения за задержкой соответствует псевдодальности, а мгновенное состояние фазы в петле слежения за несущей псевдоскорости) поступают через интерфейс 8 в блок решения навигационной задачи, где происходит дешифрация навигационного сообщения D_i(t), причем программно реализованные дешифраторы навигационных сообщений КА систем "Глонасс" и "Навстар" индивидуальны для каждого вида спутников, так как структуры навигационных сообщений указанных СРНС отличаются друг от друга.From the output of parameter estimation block 95, the signal S _i (t), pseudorange ρ to the i-th spacecraft, pseudo-speed

(the instantaneous state of the discrete phase in the delay tracking loop corresponds to the pseudorange, and the instantaneous state of the phase in the tracking loop of the pseudo-speed carrier) is transmitted via interface 8 to the block for solving the navigation problem, where the decryption of the navigation message D _i (t) takes place, moreover, the software implemented navigation decryptors Messages of the spacecraft of the Glonass and Navstar systems are individual for each type of satellites, since the structure of the navigation messages of the indicated SRNSs are different from each other.

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

 Work with the spacecraft of the Navstar system is carried out only using 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.

где ρ_i измеренная псевдодальность до i-го КА;
n размерность вектора состояния потребителя;
C скорость света,

X вектор состояния без учета относительно временного сдвига СРНС.Since spacecraft of various systems are usually located in the working constellation, it is first necessary to determine the shift Δτ of the system time scale of the Navstar satellites of the SRNS satellites relative to the Glonass SRNS timeline and only then determine the current consumer state vector. To this end, in the navigation microprocessor 10, the equation of measurements of the form is solved

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

X state vector without regard to the time shift of the SRNS.

где ρ_m вектор измерений псевдодальностей;
δ_м 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:

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.

где C скорость распространения сигнала;
ρ_i псевдодальность до i-го КА,
x_i, y_i, z_i неизвестные из навигационного сообщения D_i(t) координаты КА;

известные из навигационного сообщения 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 приемоиндикатора относительно опорного генератора СРНС;
Δτ временное рассогласование между шкалами времени СРНС двух систем.Subsequently, in the block of the navigation microprocessor 10, 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

where C is the signal propagation speed;
ρ _i pseudorange to the i-th spacecraft,
x _i , y _i , z _i unknown from the navigation message D _i (t) coordinates of the spacecraft;

spacecraft speeds known from the navigation message;

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 generator of the receiver indicator relative to the reference generator of the SRNS;
Δτ is the temporary mismatch between the SRNS time scales of the two systems.

который выводится из индикатора 17. Среднеквадратичная ошибка G оценки координат и времени равна

где s_x, σ_y, σ_z, σ_t среднеквадратичная ошибка по трем координатам и времени;
σ_ρ среднеквадратичная ошибка измерения псевдодальностей;
M геометрический фактор.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

which is derived from indicator 17. The standard error of the coordinate and time estimates G is

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

Compared with the prototype device / 3 / in the inventive device, the following advantages are achieved:
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 for the purpose of further digital processing of signals received from the spacecraft in a wide frequency band. In this case, there are no additional noise on the mirror channel, which occurs during double frequency conversion. The supply of local oscillator signals, gating signals of 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 with the help of one shaper of the reference frequency grid. The use of pulse phase and frequency detectors in the grid driver of the reference frequencies protects the device from false captures at multiple frequencies of the generator controlled by voltage, 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 receiving 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 reliability in operation 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 code or carrier, for example, in the presence of deliberate interference or during installation receiver indicator on highly dynamic objects,
e) the use of two radionavigation 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 posed to the invention are fulfilled.

Claims (2)

 A multi-channel 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 thermostated generator, a primary information processing unit, an interface unit, a navigation parameter vector determination unit, random access memory, read-only memory, characterized in that the input unit coordination of signal levels of the communication line, input / output unit of navigation parameters, second random access memory property, a second permanent storage device and an indicator, the antenna output being connected to the input of the receiver, the information output of which is connected to the information inputs of the first N-th channel of the primary information processing unit, each channel containing its own frequency-code correlator, integrator unit, multi-function generator pseudorandom sequences, the information output of the receiver is connected to the first information inputs of the frequency-code correlators of the first N-th channel of the primary sample block information blocks, the information outputs of which are connected to the information inputs of integrator blocks, the outputs of the vector of radio navigation parameters connected to the data bus, the bi-directional control bus of which is connected respectively to the control inputs of multi-function pseudorandom sequence generators, frequency-code correlators and integrator blocks, moreover, information outputs of multi-function pseudorandom sequence generators of each channel of the lane block primary information processing are connected respectively to the second information inputs of the frequency-code correlators, while the information output of the measurement unit of the vector of radio navigation parameters of the N-channel information processing unit is connected to the first input of the interface unit, the output of which is connected to the first input of the main signal level matching unit communication connected by the output to the first information bidirectional input of the unit for determining the vector of navigation parameters, information this bi-directional input is connected simultaneously with the information inputs of the first read-only memory and the first random access memory, the second bi-directional input of the signal line matching unit of the communication line connected to the information input of the input / output unit of navigation parameters, the first bi-directional output of which is connected simultaneously with the timer, the second operational a storage device and a second read-only memory device, wherein the information output is and the input-output of the block of navigation parameters is connected to the indicator, the first output of the clock synchronization of the receiver is connected to the clock inputs of the frequency-code correlators, integrator blocks, multi-function pseudorandom sequence generators and the radio navigation parameter measurement unit of the first N-th channel of the primary information processing unit, the second the receiver clock synchronization output is connected to the clock synchronization inputs of the signal trunk matching unit and the vector detecting unit and navigation parameters multichannel 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, moreover, the input of the broadband filter preselector is connected to the output of the antenna feeder, and the output is from the first input of the first low-noise amplifier, the output connected to the input of the first band-pass filter, the output of which is connected inen with the first input of the second low-noise amplifier, the output connected to the first input of the mixer, the output of which is connected to the input of the second band-pass filter, 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, moreover, 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 the amplifier and the second input of the intermediate frequency amplifier, while 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 the frequency synthesizer is connected simultaneously to the clock inputs of the frequency-code correlators, integrator blocks, multi-function pseudo generators ray sequences of the first N-th channel of the primary information processing unit and to the clock synchronization input of the vector of radio navigation parameters measurement unit, the fifth output of the frequency synthesizer is connected simultaneously with the clock synchronization inputs of the signal line matching unit of the communication highways and the unit for determining the vector of navigation parameters.

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