RU109872U1 - SATELLITE NAVIGATION SYSTEM RECEIVER - Google Patents

Abstract

 1. A device for receiving signals from a satellite navigation system, comprising an antenna connected to the input of the receiving radio frequency path; ! a demodulator that provides the selection of signals containing signals of navigation satellites in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, an era signal generator, the duration of the intervals between which is equal to the era of the satellite navigation system; ! made with relatively low power consumption blocks for tracking signals generated by navigation satellites, each of the tracking blocks determining the time of arrival of a signal from one navigation satellite to the receiving radio frequency path; ! hypothesis generator and hypothesis test unit, made with relatively high power consumption; moreover, the hypothesis is presented in a machine-readable form, the data providing the formation of a sequence of test signals corresponding to a sequence of signals generated by one of the satellites of the satellite navigation system, and the hypothesis test unit is configured to detect the presence and position, relative to signals of an era, of a sequence of test signals in signals, allocated by the demodulator in at least two eras, with that! the hypothesis test unit is configured to transmit the tested hypothesis, together with data on the indicated position, to the corresponding tracking unit for the signal of the corresponding navigation satellite, which provides continuous determination of the position of the hypotheses

Description

The utility model relates to the field of reception and processing of signals from satellite navigation systems and can be used in navigators that provide routes for vehicles and other moving objects, as well as for accelerated location determination in conditions of high level of interference, frequent loss of satellite navigation signals or multiple reflections of signals from various kinds of objects.

Currently, there are two orbital constellations of satellites that allow navigation, these are global positioning systems such as American GPS and Russian GLONASS. The commercial navigation receivers used today involve the use of open codes of one or both of them in the frequency ranges L1 and / or L2. With the advent of a new element base of two standard, dual-band receivers using all the capabilities of the visible constellation of satellites of both systems become more and more accessible and in demand among the mass consumer.

The main problem to be solved in modern navigation receivers is the fast detection and stable reception of signals, providing quick determination of the user's location and uninterrupted tracking of his subsequent movement. This task is especially relevant under difficult reception conditions, such as the high speed of movement of the object and / or the presence of many obstacles that violate the direct visibility of satellites and lead to a quick change in their visible grouping (for example, such as dense urban areas). Another aspect of building modern navigation devices is the struggle to minimize their energy consumption. One of the most resource-intensive in terms of hardware costs and power consumption of the blocks is a device that correlates the received signal with a reference pseudo-random sequence (PSP). On the one hand, to speed up the search, such a correlation processing unit should have as many parallel correlation channels as possible, and on the other hand, in order to reduce power consumption, the number of parallel channels must be minimized. Thus, the optimal receiver for solving this controversial task will be a device that allows you to quickly and accurately capture satellite signals, accurately track visible satellites and optimize power consumption, using the most suitable set of receiving channels and disconnecting modules that are not currently in use.

Known from the prior art, US patent No. 6441780, published August 27, 2002. This invention is a multi-channel dual-standard GPS-GLONASS receiver of the L1 range. The main task solved by the known device is the fight against multipath propagation of a signal received from a satellite. To assess the effect of multipath and its compensation, in addition to the correlation subchannels P (Prompt, fine tuning of the PSP) and EML (differential estimation of time synchronization using the code combination Early Minus Late - leading and retarded PSP), an additional correlation subchannel is introduced to estimate the strobe offset of the SRP of the received signal, and the code sequence supplied to the EML channel can be summed with the correcting sequence of characters. The disadvantages of this device include the relatively low speed of satellite signal capture, since the search is performed by sequentially sorting all code delays using the available set of parallel channels.

US Pat. No. 5,101,416, published March 31, 1992, proposes a receiver structure with a radio frequency path, an input signal quantizer, comprising an AGC and a block for calculating a probability density function for each of the signal levels after quantization, N signal receiving channels, and a control processor. All blocks are interconnected via a channel data bus and control signals. The processing of the useful signal in each of the N channels is performed using two correlators. In capture mode, one of them is tuned to the E sequence, and the other to the L sequence. In the signal reception mode, the first correlator is configured to receive the signal without delay (P sequence), and the second is used for convolution with the differential E-L sequence. The disadvantage of this invention, as well as the previous one, can be considered a channel structure limited in functionality and sequential enumeration of hypotheses in each of the available channels, leading to a long search time.

The solution proposed in US patent No. 6208291, published March 27, 2001, is aimed at reducing the resource consumption of the correlator. It consists in the fact that several parallel reception channels are used, in each of which all possible signal delays of a given satellite are analyzed for the detection and time synchronization using K subchannels (in the case of GPS with 1023 counting GPS, with 2 samples per chip this amounts to K = 2046 code positions), and to reduce the dimensions, the accumulation is performed using a multi-input multiplexer, one adder and a memory block to store all the results of accumulations operating at a frequency several times higher than the processing frequency ny in subchannels. This structure allows for very quick time synchronization, but it is redundant in the signal tracking mode, which inevitably entails excessive power consumption.

Application for the grant of US patent No. 20070160121, published July 12, 2007, offers an alternative approach to reducing hardware resources when building a multi-channel receiver. According to this invention, in each of the channels, a partial correlation is made for a block of symbols of length X, and the subsequent summation of the results of accumulation Y of such blocks, where X * Y is equal to the length of the SRP. In the search mode, the clock frequency in the channels can be increased several times relative to the tracking mode to improve accuracy, and partial coherent accumulations at adjacent time intervals can be used to estimate the Doppler frequency shift. Despite the increased accuracy of tuning in the channels, the search in such a device is still performed by sequentially sorting out all possible hypotheses using the existing set of channels, which leads to a long search time. In addition, the inability to turn off the excess correlators during tracking leads to increased energy consumption of such a device.

Presented in the application for the grant of US patent No. 2000096668, published April 16, 2009, the approach involves a consistent approximation of the receiver tuning accuracy to the received signal, the emphasis in this technical solution being on the Doppler frequency shift, and it is proposed to use FFT to estimate the shift, which makes this approach is not applicable for the time domain.

Another well-known solution is the solution disclosed in the application for the grant of US patent No.20050276316, published December 15, 2005, dedicated to the construction of multi-channel receivers in which the SRP is generated in one of the channels and transmitted for use in other channels in a chain, from one to another, and to obtain a code shift of one character at the input of each channel, a delay element is installed. In addition, the patent discusses the use of such a structure for receiving a GPS signal of the ranges L1 and L2. As can be seen from the description, such a solution is not aimed at speeding up the search and the accuracy of tuning in frequency and time.

The solution proposed in US patent No. 7061972, published on 06/13/2006, uses a search channel containing data memory and a set of parallel correlation channels to track satellite signals. A channel with memory allows you to write a sample of data of arbitrary length into the memory and analyze it at high speed using the correlator in the channel, the tracking channels are switched off at this time. After detecting the signal, the channel with memory is turned off, and reception is carried out using tracking channels. A drawback of this architecture is that the correlation core of the tracking channels in the capture mode is also used to process the signal recorded in memory, i.e. It is switched off from signal reception and does not allow simultaneous high-speed search and effective tracking / tuning of already found satellite signals.

The idea of recording a sample of a signal and then searching for a recorded sample is also discussed in US Pat. No. 6,091,785, published April 18, 2000. The invention provides for hardware disjoint devices for fast signal detection and a set of tracking channels. A quick search is performed by writing a replica of the received signal to the memory and comparing it with the replicas of the code in all possible combinations of frequency shift and bandwidth delay. The number of replicas stored in the memory in this case will be equal to the number of possible code shifts, which leads to the use of a large memory element that replaces the traditional memory bandwidth generator and local oscillator used in this solution to compensate for the Doppler frequency shift. Tracking channels use tracking using parallel correlators and the E, P, and L bandwidth codes to search. In addition to the large resource-intensive, it is focused only on the reception of a GPS signal, which can also be considered a disadvantage of the device described in the description of the invention.

The closest device from a technical point of view is proposed in RF patent 2341898, published December 20, 2008, on a satellite navigation receiver with a device for fast search of navigation signals in conditions of high object dynamics.

The known invention relates to radio navigation, in particular, to receivers of signals from satellite radio navigation systems GPS and GLONASS open source frequency range L1. The technical result is to reduce the search time of the signal. The receiver contains a radio frequency converter, an N channel digital correlator with a quick search device and a time stamp signal generator, and a calculator in which the quick search device contains an input GPS / GLONASS signal multiplexer, a digital carrier generator, a carrier mixer, a shift register of a signal, a code register, M multiplexers the signal, M code multiplexers, M code mixers, M-input adder, integrator, unit square calculator, second adder, RAM, a rez RAM, maximum selection unit, and a threshold device synchronizer. The quick search device provides coherent signal accumulation over an interval of 1 ms with subsequent incoherent accumulation during the time specified by the calculator depending on the expected signal-to-noise ratio. The operation of the receiver is controlled by a microprocessor (CPU), which uses ROM to store the program, for storing intermediate data, random access memory (RAM) and interacts with the rest of the receiver blocks using the data bus and the exchange unit. Data exchange with external devices relative to the receiver is carried out using the external interface unit.

The known device is designed to speed up the search and does not solve the tasks of tracking and optimizing energy consumption.

The technical result achieved by the implementation of this utility model is to reduce the ratio of energy consumed by the device to the speed of the search for signals from navigation satellites.

The technical result is achieved due to the fact that in the device for receiving signals from a satellite navigation system, the tracking blocks for satellite navigation signals are made with relatively low power consumption, and the hypothesis testing unit for the presence of a satellite navigation signal in the received radio frequency signal is made with relatively high power consumption, wherein the device comprises an antenna connected to the input of the receiving radio frequency path, a demodulator made providing the selection of the signal in, containing signals of navigation satellites, in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, an era signal generator, the duration of the intervals between which is equal to the era of the satellite navigation system, tracking blocks for signals generated by navigation satellites, each of the tracking blocks made determining the time of arrival of a signal from one navigation satellite to the receiving radio frequency path, hypothesis generator and hypothesis test unit, m hypothesis is a data presented in a machine-readable form, providing the formation of a sequence of signals being tested, corresponding to a sequence of signals generated by one of the satellites of the satellite navigation system, and the hypothesis testing unit is configured to detect the presence and position, relative to signals of an era, of a sequence of signals being tested in signals, allocated by the demodulator for at least two epochs, while the hypothesis test unit is configured to transmit and the tested hypothesis, together with data on the indicated position, to the corresponding tracking unit for the signal of the corresponding navigation satellite, which provides continuous determination of the position of the hypothesis relative to the signal of the era, and the hypothesis testing unit is also able to request a new hypothesis after checking the hypothesis, as if and in the absence of a sequence of checked signals in the signals allocated by the demodulator.

In one embodiment of the hypothesis generation unit, the hypothesis contains data presented in a machine-readable form corresponding to the Doppler frequency shift of the signal of the corresponding satellite, and the hypothesis test unit is configured to scale in time a digital sequence in accordance with the given hypothesis by the Doppler shift.

In the particular case of the implementation of the utility model, each of the signal tracking units contains a separate additional demodulator designed to extract signals containing navigation satellite signals in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, with the possibility of setting the carrier frequency, taking into account the Doppler bias, while the quick search block can be made in the form of a matched filter made in the form of a clocked shift register of the signal navigation satellites and a programmable code register, with the possibility of conducting coherent and / or incoherent correlation detection by comparing, at each step, the individual bits of the code register code and the corresponding individual bits of the shift register code, and, when a predetermined correlation value is detected, the transmission of the tested hypothesis is ensured , together with data on the indicated position corresponding to the measure at which the correlation was detected, and for other values of the correlation it is considered that There is no validity of the tested signals in the signals allocated by the demodulator.

Also, the utility model may contain at least two quick search blocks made with separate or with one common clock shift signal register of navigation satellites.

In the particular case of the invention, a predetermined correlation value can be set by a hardware method by indicating a range of correlation values that satisfy the search conditions. Moreover, as the detected correlation value, you can select the maximum found correlation value, provided that it is in the specified range. The utility model can be implemented with the possibility of accumulation of correlation data for at least two epochs.

Also, in the particular case, part of the tracking blocks for signals generated by navigation satellites is made by providing the indicated blocks with increased accuracy of determining the time of arrival of the signal of one navigation satellite in the receiving radio frequency path, and if the predetermined correlation value is less than the second predetermined correlation value, the transmission of the tested hypothesis, together with data on the indicated position corresponding to the beat, to the signal tracking unit, providing increased constant accuracy. The signal generator of the era in one embodiment of the utility model can be made in the form of a frequency divider of the signals generated by the clock generator common to all blocks of the device, in addition, the hypothesis generation unit can be executed by generating the signal of the absence of hypotheses, after enumerating all possible hypotheses, and the block hypothesis testing is made with the possibility of disconnecting from the power supply circuits when forming the specified signal.

A block diagram of a utility model comprising a satellite navigation receiver with a correlation processing unit for navigation signals is shown in FIG.

Figure 2 shows an input interface unit used in conjunction with a utility model.

The structure of a simulator designed to verify the health of a utility model is presented in FIG. 3.

Functional diagram of the channel is presented in Fig.4.

The channel structure of increased accuracy is shown in FIG.

One embodiment of a programmable delay line implemented in a utility model is disclosed in FIG. 6.

7 shows a channel for direct reading of data intended for the implementation of program search methods.

Fig. 8 discloses one embodiment of a hypothesis test block according to a utility model.

The receiver shown in FIG. 1 is primarily intended for receiving three types of signals: GLONASS signals of the L1 and L2 range and GPS signal of the L1 range.

The receiver comprises a schematic antenna connected to the input of the receiving radio frequency (RF) path, comprising a demodulator, for example, a local oscillator type and / or using digital filtering and the selection of a modulating signal. The demodulator provides the selection of signals containing signals of navigation satellites in a predetermined range of carrier frequencies, for example, GLONASS signals of the L1 and L2 range and GPS signal of the L1 range from the output signal of the receiving radio frequency path.

An epoch signal generator or a timeline generator, shown in FIG. 1 as a separate block and functionally corresponding inputs of other blocks and utility model modules associated with it, generates signals whose interval duration is equal to the era of the satellite navigation system. The timeline generator generates a receiver timeline, which is a pulse of the millisecond Epoch era with a duration of one clock cycle clk and a period of 1 ms, and generates the clock signal clk itself, which is necessary to synchronize the operation of all blocks and modules of the receiver.

The device also contains shown in FIG. 1 blocks for tracking signals generated by navigation satellites, made in the form of tracking channels and / or channels of high accuracy, made with relatively low power consumption. Each of the tracking blocks is mainly made determining the time of arrival of the signal of one navigation satellite to the receiving radio frequency path or otherwise determining the position of the satellite signal relative to the generated signal of the era, and accumulating the convolution of the signal with the reference code sequence for a duration of one era to extract the received information.

Reduced power consumption of signal tracking units is achieved by reducing the number and / or frequency of operations necessary to determine the time parameters of the signal of the corresponding navigation satellite. In particular, the tracking unit can be configured to determine the signal position of the corresponding navigation satellite, based on the signal-to-noise ratio of the received signal, the multipath propagation medium of the signal, the final velocity of the object on which the utility model is installed, and other features of the operation of the device. Accordingly, under good reception conditions, the position of the signal is determined in a predetermined time range, and therefore the region of uncertainty and the accuracy of the analysis during time synchronization can be reduced by turning off some of the correlators in the block. T.O. part of the period of operation of the tracking unit may be in rest mode when, minimally sufficient functionality is saved and energy consumption is significantly reduced or completely stopped.

In the event that the Doppler shift can significantly degrade the reception of the satellite navigation signal, each of the signal tracking units contains a separate additional demodulator designed to extract signals containing navigation satellite signals in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, with the possibility setting the carrier frequency, taking into account the Doppler shift.

Signal tracking blocks can be of various types, both with minimal functionality, allowing only to keep synchronization with the detected satellite signal and highlight a useful signal, and with advanced functionality (channels of increased accuracy), which allow additional signal search in poor reception conditions.

In one embodiment, the tracking unit may be a direct data reading channel providing accumulation, necessary preliminary processing, for example, such as correction of the Doppler frequency shift, and outputting data upon request of external devices.

The device also contains a hypothesis generator, in a particular case, made in the form of a pseudo-random sequence generator or code generator. The hypothesis test block, implemented, for example, as a quick search block, is made with relatively high energy consumption, this, in particular, is due to the fact that the hypothesis test block should be able to check for a minimum time the presence of a satellite signal (or SRP) in the received RF signal , determine the time shift of the satellite signal relative to the signal of the era, and also, if possible, determine the Doppler frequency shift caused by the mutual movement of the satellite and the object on which the receiver a. The solution to this problem requires a large number of operations. Including parallel ones, so it is impractical to constantly use a large number of hypothesis test blocks, and, in the absence of the need to test hypotheses, this block can be de-energized. The hypothesis itself may contain only the SRP of one of the satellites, and may also contain additional data, for example, the Doppler frequency shift, based on the estimated speed of the object relative to the satellite. The hypothesis test unit provides the ability to detect the presence and position, relative to signals of an era, of a sequence of signals being tested in the signals allocated by the demodulator for at least two epochs.

The hypothesis test unit is connected to the data, address and control bus of the device, which makes it possible to transmit the tested hypothesis, together with data on the indicated position, to one of the blocks for tracking the signal of the detected navigation satellite, which provides continuous determination and adjustment of the hypothesis position relative to the signal of the epoch and providing, thus, the optimal allocation of the received signal. Also, the hypothesis test unit is configured to query and / or install through the data bus, addresses and controls, a new hypothesis after testing the hypothesis, both in the presence and absence of a sequence of signals being tested in the signals allocated by the demodulator. The hypothesis testing unit can provide both independent generation of several Doppler bias values, providing parallel verification of signals taking into account the bias, and receive them from the outside, for example, the formation of the Doppler bias value can be provided by the hypothesis generating unit. In any case, the hypothesis test unit may provide the ability to scale over time a digital sequence, in accordance with a given Doppler shift. For the simple realization of this possibility, the hypothesis test block can operate at a clock frequency that is significantly higher than the frequency of the PSD bits or have a set of identical blocks providing a parallel analysis of all or only part of the uncertainty region in frequency and time, which also increases its energy consumption.

In the diagram shown in FIG. 1, the hypothesis test block is a quick search block, which is made in the form of a matched filter made in the form of a clock shift shift register of the navigation satellite signal and a programmable code register, with the possibility of conducting coherent and / or incoherent correlation detection by comparison , at each beat, of the individual bits of the code register code and the corresponding individual bits of the code shift register. The use of incoherent accumulation in this unit can significantly increase the probability of detecting a satellite signal in an adverse interference environment. The transmission of the tested hypothesis, upon detection of a predetermined correlation value, together with data on the indicated position corresponding to the clock at which the correlation was detected, and, if necessary, the Doppler shift value is provided either via the common address and control data bus, or via the corresponding interfaces .

The receiver depicted in FIG. 1 may be operated under the control of an external control unit, which may consist of a central processor, program memory such as, for example, ROM, and random access memory for storing intermediate and final data. At the same time, the integration of all blocks into a single functionally complete device is performed by means of an exchange unit that provides the necessary exchange of data and control commands.

To exchange data with external devices that are relatively useful to the model, the input interface blocks and the external interface block are used, while the input interface block is designed to convert the incoming signal into the format of computer-readable data used in the utility model, and the external interface block performs the inverse transformation necessary for data exchange with external devices.

In the future, some embodiments of the device are disclosed in more detail.

The solution to the problem of quick search, tracking and optimization of energy consumption is solved using the Correlation Processing Unit (BKO). BKO is, from a functional point of view, a multichannel correlator (MCC) with various types of channels, consisting of Q Quick Search Block (BBP), Z Channels of Increased Accuracy (CBT), N Tracking Channels (SC), Kapala Direct Data Reading (CPCH) ), Input Interface Unit (BVI), Exchange Unit (BO), Signal Simulator (IS) and Timeline Generator (GVS). For greater clarity of the drawings, many identical parallel channels and their interblock connections are shown on the example of one block of this type, and the signals transmitted from block to block are multi-bit buses, which include all signals transmitted between these blocks.

The input interface unit is designed to organize the interaction between the BKO and the radio path, as well as connect the inputs of the correlation channels to the output of the signal simulator in the self-test mode.

The signals to be processed in the BKO are fed to its input from three radio frequency ones. paths of the analog receiving-amplifying part of the navigation receiver: LI GPS (SA), L1 GLONASS (ST) and L2 GLONASS (ST). Each of the three input signals is complex. The real and imaginary components of the signals can be single-bit or two-bit in the sign-amplitude format.

From the BVI output, the signals are fed to the inputs of the search and tracking channels, as well as the direct channel, where they are processed in accordance with the specified settings for each channel. In operating mode, the IWC functions in conjunction with the navigation processor (CPU). The CPU, through the Exchange Unit, reads the results of the correlation processing from the channels and writes the channel control data to the corresponding channel registers. The clock signals necessary for synchronous multi-channel correlation processing are generated in the Timeline Generator.

Consider the device of individual blocks and their interaction in the process of work in more detail:

As can be seen from the drawing, the input interface block shown in Figure 2, in addition to three multiplexers (MUX GN1, MUX GN2 and MUX GP1), which switch the input of the BKO into the self-test mode and back to the operating mode, it implements counters of input signal levels (Counter GN1, GN2 Counter and GP1 Counter). Counters are designed to calculate the average level of signals coming from the radio frequency part. To assess the level of signals in each subchannel, over a given interval, the number of unit states of each of the bits of the input signals is accumulated. At the end of the accumulation, the result is transmitted to the output of the device and can be used to adjust the level of the input AGC. For self-testing, the GPS (MUX GP1) or GLONASS (MUX GN1 and MUX GN2) signals are sent to the corresponding inputs of the multiplexers.

The simulator is designed to generate a signal that repeats with sufficient accuracy the signal of one of the GPS or GLONASS satellites. This signal can be used instead of the input signal from the radio part in the receiver, which allows you to check the operation of the modules included in its composition.

The composition of the simulator shown in Fig. 3 includes a signal generator, a bandwidth generator, a modulator, a Doppler local oscillator, a multiplier, a noise generator with a scaling multiplier, and an adder.

The SRP generator is used to set the reference SRP simulating the satellite SRP. The modulator is used to superimpose a meander with a frequency of 50 Hz generated by the signal generator on the output signal of the PSP generator. This simulates information sequence bits that modulate satellite bandwidth. The Doppler local oscillator serves to form the reference signal, which is used to transfer the SRP from zero frequency to the Doppler frequency. Noise level is set by scaling factor Кш. After the formation of the required mixture of signal and noise in the adder, the received signal is limited by a limiter to the input bit depth of the Correlation Processing Unit.

The exchange unit, in the most general case, is a microcontroller connected to the CPU by a data bus. When transmitting control signals from the CPU to the BKO blocks, the microcontroller receives control signals from the CPU, decodes them, reads the necessary data from the RAM memory and transfers them to the corresponding blocks. When transferring data from blocks to the CPU, the microcontroller performs the reverse operation, reading the received data from the outputs of the blocks and writing them to RAM for further processing in the CPU. Another implementation option for the BO can be a block of registers, which is a dual-port RAM that stores the current settings of the channels and the results of their work, access to the elements of which on the one hand is available for all BKO units, and on the other hand, for the CPU.

The timeline generator generates a receiver timeline, which is a pulse of the millisecond Epoch era with a duration of one clock cycle clk and a period of 1 ms, and generates the clock signal clk itself, which is necessary to synchronize the operation of all blocks and modules of the receiver.

Tracking channels (SC) are designed to track the signal of GPS L1 / GLONASS L1 / GLONASS L2 satellites. The channel includes the Prompt (P) direct signal subchannel and the Early-Minus-Late (EML) differential subchannel. In the Prompt subchannel, the convolution of the signal transferred to the zero frequency from the IF (taking into account the Doppler frequency) from the given satellite bandwidth is calculated. In the EML subchannel, the signal at zero frequency is collapsed with another, differential PSP, which is a product of the early and late versions of the PSP. This gives a convolution with a differential correlation characteristic having peaks of different signs, respectively, for the early and late SRP. The monitoring process is controlled by the CPU, periodically reading the calculated convolutions of the direct and differential channels and giving corrections of the PSP phase depending on the size and sign of the convolutions of the direct and differential subchannels. From the side of the CPU, the local oscillator frequency, the chip frequency of the PSP and their initial phases are set, and the PSP itself formed in the channel is also set.

At the input of the channel shown in Fig. 4, using a multiplexer (MUX) controlled by a CPU signal S (Select), a choice is made between GPS signals L1 / GLONASS L1 / GLONASS L2, after which the selected signal is multiplied by the reference local oscillator signal (Gen. carried). Then the signal from the output of the multiplexer is fed into two subchannels: Prompt and EML. In the Prompt subchannel, the signal is multiplied by the reference SRP, after which it is accumulated in the integrator (Int. P) for the duration of the epoch. In the EML subchannel, the signal is multiplied by the differential SRP, after which it is also accumulated in the corresponding integrator (Int.EML) for the duration of the epoch. The PSP generator is common to two subchannels; it generates a reference PSP, from which a differential PSP is formed using the delay line and a subtractor.

Channels of increased accuracy (KPT) can also be used as tracking channels GPS L1 / GLONASS L1 / GLONASS L2. At the same time, a greater number of subchannels providing greater tracking accuracy make them most effective when tracking satellites with a small signal to noise ratio or in conditions of strong multipath signal propagation.

Another purpose of high accuracy channels in the device is to search for a useful signal in cases where the satellite signal is detected by a hypothesis test unit (quick search unit), but the accuracy of tracking it is still insufficient according to some criteria of the signal detection algorithm.

Each of the channels of increased accuracy, presented in Figure 5, consists of L subchannels with adjustable detuning according to the time of arrival of the input signal, from 0 to t cycles of the sampling frequency. The channel transfers the signal from the IF taking into account the Doppler frequency to zero (similar to the CS channels), after which it turns it off from the IF and accumulates the result for a given time (from 1 to 32 epochs). Thus, in each subchannel, it is possible to obtain an estimate of the received signal for a duration exceeding the duration of the era.

The operation of each subchannel in the CBT channel is allowed by writing a unit to the corresponding bit of the L-bit Status Register. If the subchannel is disabled, it switches to low power mode. Thus, by prohibiting the operation of all L subchannels, the entire channel is deactivated.

The results of the channel’s work are accumulations in integrators over the duration of an era (Int.1) and the duration of several eras (Int.2). The duration of accumulation is set by the CPU through the BO as a number from 0 to 31, which determines the number of epochs during which accumulations will be made.

The formation of the reference SRP for each of the subchannels is performed using one Code Generator and a Programmable Delay Line (PLZ) with L-1 taps. The number of taps is one less than the number of subchannels, since the reference channel is fed to the first channel without delay.

In one of the variants of the programmable delay line (PLZ), shown in Fig. 6, to connect any element of the Delay Line that stores the SRP samples to any of the L-1 outputs of the PLZ, L-1 switches are used, each of which is connected to the elements by its inputs delay lines. The switching of the switches is controlled by the Delay Control Unit, which receives the control signal from the exchange unit and decodes it into the control signals of the switches.

The direct data reading channel (Fig. 7) is designed to implement software search methods using FFT or other software search and tracking algorithms. It includes an input multiplexer, a local oscillator for signal transfer from the inverter and Doppler shift compensation, an integrator with a programmable accumulation duration and a data buffer of the FIFO type.

Initially, the input data falls into the multiplexer, which, depending on the settings, selects one of the inputs. Then the data is transferred from the IF to the zero frequency by multiplying by the local oscillator signal. The multiplication result is accumulated in the integrator, the accumulation results are stored in a FIFO type data buffer with a depth of 2048 samples, from where the CPU can read them through the BO.

The hypothesis test block, for example, the BBP shown in Fig. 8, operates as follows:

Quick search blocks are designed to search for satellite signals in the GPS L1 / GLONASS L1 / GLONASS L2 bands. The search is performed for all hypotheses on the delay of the SRP at a given SRP and Doppler frequency, in connection with which this block is, in fact, a block for testing the hypothesis. The search result is the amplitude of the maximum received correlation peak and its position relative to the epoch signal in chips and fractions of a chip with a half-chip discrete.

The BBP calculates the cross-correlation function (WKF) of the input signal and SRP at 2046 (GPS) / 2044 (GLONASS) SRP positions relative to the signal.

The choice of the reference SRP used for the search is carried out by applying the control signal “GP / GN”, which switches the code register storing the reference sequences from the GPS search mode to the GLONASS search mode. Correlation values coherently accumulate over the duration of 1–16 epochs, after which the result of coherent accumulation is taken into account in incoherent accumulation from 1 to 16 times.

The UPS can be in standby mode and in search mode. In standby mode, processing of incoming data is not performed, the results of the last search are stored in the RAM unit and are available to the CPU through the exchange unit. At the command of the CPU, the Quick Search Box switches to search mode or stops. This is done by applying a start / stop signal to the corresponding input of the control unit.

The control unit controls the overall operation of the device and generates all the necessary signals for operation. The block generates the necessary for the operation of the Code Multiplexers (MUXc 1 - MUXc M) and the Signal Multiplexers (MUXs 1 -MUXs M), as well as the Code Mixers (Mix Code 1 - Mix Code M), a synchronization signal (Synchro). Stopping this signal stops the operation of these units. In addition, the control unit generates an on / off signal (Enable, shown by a dashed line for greater clarity of the drawing), by means of which the on / off of the most power-consuming power supply units is turned on / off. Thus, using the “Synchro” and “EPAe” signals, energy savings are achieved when the device is turned off, and at the same time, the availability of its RAM for the CPU. In addition, the control unit manages the settings for coherent and incoherent accumulations, switching the key for outputting information from RAM KN to the CIC filter, changing the order of the CIC filter and addressing the data in RAM when writing / reading.

In the search mode, the block input signals from the antenna and the radio frequency path are sent to the multiplexer (MUX), where one of the three input signals is selected for processing. Then the signal is multiplied by the reference signal of the Doppler local oscillator, the frequency of which is set by the CPU. The result of multiplication is decimated n times (if necessary, until 2 samples per GPS chip and 4 samples per GLONASS chip are reached) and stored in the delay line. Thus, 2046 (GPS) / 2044 (GLO) results are stored, after which the BPS starts calculating the WKF of the samples of the stored signal from the memory bandwidth stored in the memory. The calculated complex VKF is accumulated in the buffer of coherent accumulations at the address corresponding to the analyzed position of the signal relative to the SRP (at the initial moment, at address 0). At the first coherent accumulation, the number is loaded into RAM KN (RAM of coherent accumulation), with the rest - accumulation.

After that, the sample stored in the delay line is cyclically shifted, the VKF is again calculated and accumulated in the RAM of the SC at the following address. This is repeated 2046/2044 times, which gives the VKF for all the mutual positions of the data regarding the SRP. To obtain coherent accumulation over a period of several epochs, this calculation process is repeated several times, the results of subsequent complex VKF are summed up with the previous ones in RAM of the SC. The number of repetitions is set by the CPU.

The generated coherent estimates of all positions of the shift of the reference code are issued through a key controlled by the Control Unit to the input of the FIR filter with unit coefficients (CIC). Since the signal is processed at a frequency higher than the chip one, the use of filtering allows one to collect the energy of several chips into one and thus maximize the true correlation peak. The order of the filter changes depending on the settings transmitted from the Control Unit (for GPS 2nd, for GLONASS 4th).

Based on the accumulation of a given number of coherent accumulations and filtering, the quick search unit produces incoherent accumulation: calculates the power for each position of coherent accumulation and accumulates them in the RAM NKN (incoherent accumulations). At the first access to the NKN RAM, data is loaded into the RAM, while the rest is accumulated.

The entire cycle above is repeated as many times as the signal from the CPU sets incoherent accumulations. From the results of the ICH, the maximum is selected and its position is remembered; if there are several highs, the first one of them is remembered. In addition, the results of the ICH throughout the duration of the BBP operation are compared with the threshold for early termination of the search (Threshold device). If any accumulation exceeds this threshold, the search stops, and the accumulation position is stored in the maximum search block. At the end of all operations, the machine switches to standby mode. The above search procedure applies to both GPS and GLONASS.

The technical result from the implementation of the device is that energy consumption is optimized due to the optimal on / off correlation channels most suitable for solving the current problem (BBP, SC and KPT). Expanding the accuracy and speed of searching for new satellites due to coherently incoherent accumulation in BBP Increased tracking capabilities of a multipath signal through the use of CBT. The ability to accurately additional search for signals using CBT. The ability to evaluate the raw signal in the correlators by using the Channel for direct reading of data.

Claims (11)

1. A device for receiving signals from a satellite navigation system, comprising an antenna connected to the input of the receiving radio frequency path; a demodulator that provides the selection of signals containing signals of navigation satellites in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, an era signal generator, the duration of the intervals between which is equal to the era of the satellite navigation system; made with relatively low power consumption blocks for tracking signals generated by navigation satellites, each of the tracking blocks determining the time of arrival of a signal from one navigation satellite to the receiving radio frequency path; hypothesis generator and hypothesis test unit, made with relatively high power consumption; moreover, the hypothesis is presented in a machine-readable form, the data providing the formation of a sequence of test signals corresponding to the sequence of signals generated by one of the satellites of the satellite navigation system, and the hypothesis test unit is configured to detect the presence and position, relative to the signals of the era, of the sequence of test signals in the signals, allocated by the demodulator in at least two eras, while the hypothesis test unit is configured to transmit the tested hypothesis, together with data on the indicated position, to the corresponding tracking unit for the signal of the corresponding navigation satellite, which provides continuous determination of the position of the hypothesis relative to the signal of the era, and the hypothesis test unit is also configured to request a new hypothesis after the hypothesis is tested both in the presence and in the absence of a sequence of tested signals in the signals allocated by the demodulator. 2. The device according to claim 1, in which the hypothesis generator is made forming a hypothesis, further containing data presented in a machine-readable form corresponding to the Doppler frequency shift of the signal of the corresponding satellite, and the hypothesis testing unit is configured to scale in time a digital sequence in accordance with the specified Doppler hypothesis offset. 3. The device according to claim 2, in which each of the signal tracking units contains a separate additional demodulator, configured to extract signals containing navigation satellite signals in a predetermined range of carrier frequencies from the output signal of the receiving radio frequency path, with the possibility of setting the carrier frequency, with Doppler shift. 4. The device according to claim 3, characterized in that a quick search unit is implemented in it, made in the form of a matched filter made in the form of a clock shift register of the navigation satellite signal and a programmable code register, with the possibility of conducting coherent and / or incoherent detection of correlation by comparing, at each step, individual bits of the code register code and the corresponding individual bits of the code shift register, and upon detection of a predetermined correlation value is provided tested the hypothesis with the data about the specified position corresponding to tact, which has a correlation, and for other values of the correlation is considered that the sequence of scanned signals into signals extracted by the demodulator, is absent. 5. The device according to claim 4, containing at least two quick search blocks made with separate or with one common clock shift shift register of the navigation satellite signal. 6. The device according to claim 4, in which the quick search unit is configured to set a predetermined correlation value by indicating a range. 7. The device according to claim 6, in which the quick search unit is configured to select the maximum correlation value as the detected correlation value, provided that it is in the specified range. 8. The device according to claim 4, configured to accumulate correlation data for at least two eras. 9. The device according to claim 4, in which some of the blocks for tracking signals generated by navigation satellites are designed to provide increased accuracy in determining the time of arrival of a signal from one navigation satellite to the receiving radio frequency channel; moreover, if the predetermined correlation value is less than the second predetermined correlation value, the tested hypothesis is transmitted, together with data on the indicated position corresponding to the clock, to the signal tracking unit with increased accuracy. 10. The device according to claim 1, in which the signal generator of the era is made in the form of a frequency divider of the signals generated by the clock generator common to all blocks of the device. 11. The device according to claim 1, in which the hypothesis generation unit is configured to generate a signal of the absence of hypotheses after enumerating all possible hypotheses, and the hypothesis testing unit is configured to disconnect from power circuits when generating the specified signal.