RU2158933C1 - System for reception and transmission of information messages using radio navigation channel of pulse-phase radio navigation system - Google Patents

Abstract

FIELD: radio navigation aids. SUBSTANCE: device may be used for transmission of service information, for example, monitoring-correction information, in differential systems of satellite navigation systems. Device has transmitter and receiver, which are connected by means of navigation channel. Transmitter has generator of reference signals, antenna transmitting unit, comparison unit, counter, control code register, intermediate storage message writing and encoding units, generator of correction codes, and encoding control unit. Receiver has receiving converter, clock oscillator, counter, units for sample generation, set sampling storage, storage of received message, message decoding and message correction, output storage unit and decoding control unit. In addition, transmitter has units for writing number of lines in message and for control of correction code generation. Receiver has additional units for storage of line samples, detection of message start and control of message correction. Transmitter of system generates pulse sets of radio navigation signal and provides temporal modulation of six last pulses of sets transmitted in messages and correction codes. Receive receives radio navigation signal, detects transmitted messages, detects and corrects errors in received messages. EFFECT: possibility to transmit information messages of varying length, increased speed of information transmission. 2 dwg, 5 tbl

Description

 The invention relates to radio navigation and can be used to transmit and receive service information on the radio navigation channel, pulse-phase radio navigation system (IFRNS), in particular control and corrective information (KKI) when implementing differential subsystems of satellite radio navigation systems (SRNS).

 There are various systems for transmitting information on the radio navigation channel IFRNS.

 In [1, 2], the information transmission system in the LORAN-C IFRS was described, using the 0/1 amplitude “flicker” of the first two pulses in the pulse train of the LORAN-C navigation signal to transmit messages about the output of the IFRNS transmitting station parameters beyond the technological tolerances. This system is characterized by the limited types of messages that can be transmitted, and the relatively low noise immunity of the transmission, due to the chosen type of modulation - simple amplitude manipulation.

 Significantly better characteristics are possessed by the radio navigation channel information transmission system used in the Chaika IFRNS [3]. The system provides for the formation of an additional service pulse to the burst of pulses of the navigation signal, which is manipulated by the phase of the carrier in accordance with the transmitted service message using a Reorth-Miller biorthogonal code to increase the noise immunity. The disadvantages of this system, in addition to the need to form additional service impulses for the transmission of messages, include the low effective information transfer rate, which, given the existing IFRNS characteristics, according to [3], does not exceed 3 baud.

 To some extent, the drawbacks of the system [3] are deprived of the system for transmitting information on the radio-navigation channel IFRNS described in [4]. To transmit information in the system, it is proposed to use temporary (phase) manipulation of ± 1 μs of the last two of the eight pulses of a packet of pulses of a navigation signal LORAN-C. Moreover, in order to reduce losses for the main function of the system - navigation, due to the use of the radio navigation signal to transmit information, it is proposed in [4] to use combinations with zero sum of modulation indices on a group of bursts of pulses of the navigation signal.

 A further development of the system [4] is the EUROFIX system [5, 6], in which three-level (-1, 0, +1) time (phase) modulation with a manipulation level of ± 1 μs of the last six pulses in a burst of pulses of a navigation signal is used to transmit information LORAN-C. The main purpose of the system is to transmit to consumers messages with control and corrective information (CQI) when implementing the differential subsystem of the satellite radio navigation system (SRNS). To reduce losses in the implementation of the navigation function, combinations with zero sum of modulation indices within each group of six pulses are used. To increase the noise immunity of the transmission of information, it is envisaged that each message be accompanied by corrective codes, in particular the Reed-Solomon code, which, when receiving information, will detect and correct erroneously received message elements.

 The EUROFIX system [6], in which information messages are transmitted and received via the IFRNS radio navigation channel, is adopted as a prototype.

 The block diagram of the prototype system is shown in FIG. 1. The prototype system contains a transmitter 1 and a receiver 2. The transmitter 1 includes an antenna-transmitting device (APU) 3, a reference signal shaper (FOS) 4, a counter (MF) 5, a control code register (RCU) 6, a comparison unit (BS) 7, intermediate storage unit (BCH) 8, encoding unit (BC) 9, encoding control unit (BEC) 10, correction code generator (FCC) 11 and message recording unit (BSS) 12. The message input of BPS 12 is informational transmitter input 1. Information inputs and outputs BZS 12, FKK 11, BUK 10, BK 9 and BPH 8 are connected by an information bus onnogo exchange. The output of the control code BPH 8 is connected to the corresponding input of the control switch 6, the outputs of the bits of which are connected to the second inputs of the corresponding bits of the BS 7, the first inputs of the bits of which are connected to the outputs of the corresponding bits of the SC 5, the input of the clock pulses of which is connected to the first output of FOS 4, the second and third the outputs of which are connected respectively to the input of the recording pulse RKU 6 and the driving input BUK 10. The output of the BS 7 is connected to the input of the driving pulses APU 3, the output of the navigation signals which is the output of the radio signals before Atchik 1.

 The composition of the receiver 2 includes a receiving-converting device (PPU) 13, a clock signal shaper (FCS) 14, a sample forming unit (BFO) 15, a counter (MF) 16, a unit for storing sample packets (BHOP) 17, a decoding control unit (ECU) ) 18, a decoding unit (DB) 19, a received message storage unit (BHPS) 20, a message correction unit (BCS) 21 and an output storage unit (WBH) 22. The message output WBH 22 is an information output of the receiver. Information inputs and outputs VBH 22, BKS 21, BHPS 20, BD 19, BUD 18 and BHOP 17 are connected by an information exchange bus. The BHOP code input 17 is connected to the output of the BFD 15, the control and information inputs of which are connected respectively to the output of the signal strobe of the PPU 13 and to the outputs of the corresponding discharges SCh 16. The clock input SCh 16 is connected to the first clock output of the FCS 14, the input of the synchronization signal of which is connected to the output clock pulses PPU 13, and the second clock output of the FCS 14 is connected to the control input of the ECU 18. The input of navigation signals PPU 13 is the input of the radio signals of the receiver 2, which is connected by the radio navigation channel with the radio signal output transmitter 1.

 The prototype system works as follows.

 In accordance with standard procedures described, for example, in [7; 8, p. 311-319; 9, sect. 2.4, 3.2, 3.3, Ch. 4], the transmitter 1 generates at the output of the radio signals the next with a given period bursts of pulses of the navigation signal, which are transmitted via the radio navigation channel to the input of the radio signals of receiver 2.

According to [5, 6], in the prototype system when transmitting messages, combinations with a zero sum of modulation indices within a group of six pulses are used. Accordingly, with the base of the modulation code m = 3 and the sending length n = 6, the number of such combinations is A ₀ (3.6) = 141, which allows using a single packet of pulses of the navigation signal to transmit a word of seven bits (2 ⁷ = 128 <141) . In this regard, in the prototype system, it is assumed that each message (P) consists of 8 words of 7 binary bits in each, a total of 56 bits. In addition, each complete message (W) transmitted via the radio navigation channel contains the information part - P - and correction codes.

 The message P to be transmitted is received at the information input of the transmitter 1 and is recorded (with write permission) in the BSS 12 in the form of a block of 8 seven-bit words. Then, by the control commands from the BUK 10, the delay (phase) of the last six pulses in the packets of the radio navigation signal of the transmitter 1 is modulated sequentially by each of the words of the transmitted message, for example, as follows. From the third input of FOS 4, a pulse corresponding to the moment of the end of the second radio pulse from the pulse train of the navigation signal is supplied to the driving input of the BUK 10.

 In BUK 10, the number of symbols (pulses modulated by information delay) to be transmitted is set, η = n = 6, and a command is generated to transmit the first of 8 words from BSS 12 to FKK 11 and to BK 9. In FKK 11, it starts in accordance with algorithms described, for example, in [10, p. 128-133, 224-231, 435-446; 11, p. 304-310, 391-398], the formation of correction codes. In BC 9, each word of 1 = 7 binary bits is associated with an a priori established combination of n • q = 12 binary bits, where n = 6 is the number of characters modulated by the base code m = 3, q = 2 are two bits that describe the state of each of n characters in the ternary system (-1, 0, 1). From BC 9, a combination of n x q characters is recorded in BPH 8.

 From the second and third outputs of FOS 4, the following pulses are received at the input of the write pulse of CGC 6 and the control input of CUK 10, according to which from the output of the control code BPH 8 the first two bits of n pairs are copied to CGC 6. In CUK 10 the number decreases by one symbols η to be transmitted, and the condition η = 0 is checked. For η> 0, the BEECH 10 generates a shift command in the BPH 8 of the combination 1 written in it by two bits, preparing the modulation of the next pulse of the navigation signal. At the same time, the control code recorded in RKU 6 is sent to the second inputs of the corresponding bits of BS 7, where it is compared with the current state of the corresponding bits of SCh 5, the clock pulses of which receive pulses from the first output of FOS 4, providing a conversion period of SCh 5 equal to the pulse repetition interval in the pulse train of the navigation signal of the transmitter 1. With the coincidence of the states of the corresponding bits MF 5 and RKU 6 BS 7 generates pulses arriving at the input of the driving pulses APU 3, which generates on its own During the next navigation signal from the navigation signal pulse burst transmitter 1. In this state change q bits BCCH shift 6 provides the time of formation of the next pulse in the AAP 3 1 microsecond increments within ± 1 microsecond.

 Thus, one character is transmitted.

 Then, the procedure for transmitting the symbol described above is repeated, providing sequential transmission of six modulated pulses to the radio navigation channel, which corresponds to the transmission of one binary word of seven bits.

If the condition η = 0 is fulfilled, the BUK 10 transmits to BPH 8 a command to set the initial code corresponding to the unbiased pulse state in the pulse train of the navigation signal at its output, which is rewritten to FCU 6 at the next pulse from FOS 4, after which FOS 4 stops issuing pulses : to the SCh 5 clock input - before the start of the formation of the next packet of the navigation signal, and to the RKU recording input b and the BUK 10 input - until the end of the formation of the second pulse of the next pack. At the same time, the BUK 10 increases by one the number of transmitted words set in it (λ _i ). Then, the BUK 10 checks successively the fulfillment of the conditions λ _i ≤8 and λ _i ≤λ _o = 30, where according to [5, 6] λ _o is the total number transmitted words in the prototype system, including the actual informational message and corrective codes.

If λ _i <8, then upon the resumption of pulses from FOS 4 to the input input BUK 10, the entire procedure for transmitting the word described above is repeated, and each time the word from message P is transmitted from BSS 12 to FKK 11 and to BK 9, the number of which is set by the value N _i = λ _i-1 +1.
If λ _i = 8, which corresponds to the end of the transmission of the information part of message W of 8 words, then when the impulses from FOS 4 to BUK 10 are resumed, the word transfer procedure is repeated, but the transmission of words from BSS 12 to FKK 11 and to BK 9 stops and FKK 11 at the command of the BUK 10 is transferred from the mode of generating corrective codes to the mode of word-by-word transmission of these codes to BC 9.

If λ _i = 30, then BEECH 10 gives a command to reset FCS 11, sets the value λ = 0 and transmits permission to write the next message of 56 bits to BSS 12, after which the entire procedure for transmitting the next message described above is repeated.

 The bursts of pulses of the navigation signal, in each of which the six last pulses are modulated by the delay (phase) in this way with an information message, from the output of the radio signals of the transmitter 1 through the radio navigation channel are received through the input of the radio signals of the receiver 2 to the input of the navigation signal PPU 13, which, in accordance with the algorithms, described, for example, in [9, p. 121-142], detects and monitors the received signal. At the same time, video pulses are generated at the output of the signal gate of the PPU 13, corresponding to the moments of receiving at the receiver 2 the marker position of each individual pulse from the navigation signal of the transmitter 1, and video pulses are formed at the output of the synchronization pulses of the PPU 13, which track the value of the moments of reception of the marker positions of the navigation pulses averaged over the tracking interval the signal of the transmitter 1 and, consequently, synchronized with the period and the moments of the beginning of reception in the receiver 2 packs of radio pulses of the navigation system drove the transmitter 1. The marker position refers to a priori defined position in each pulse of the navigation signal of transmitter 1, at which the radio navigation parameter is counted in receiver 2.

 The video pulses from the output of the clock pulses of the PPU 13 are fed to the input of the FCS clock signal 14, which generates clock pulses synchronized with these video pulses at the first clock output, which are fed to the clock input of the SCh 16 and provide the formation of the counting period of the SCh 16, synchronous and common-mode with the average reception times the receiver 2 marker positions of the pulses of the navigation signal of the transmitter 1. Cyclically changing code from the outputs of the corresponding bits MF 16 is fed to the information inputs of the BFO 15, in torus at receipt on its control input of a video signal output from the PPU 13 is fixed strobe current state of respective bits Cq 16.

 At the same time, a countdown is formed at the output of the BFO 15, proportional to the delay (-1, 0, +1) μs of a specific pulse from the packet relative to the moments of reception of pulses averaged over the tracking interval from the pulse packets of the navigation signal of transmitter 1.

 Then, according to the control commands from the ECU 18, the received message is decoded, the error in the received message is selected and corrected, and the information part of the message is recorded, for example, as follows.

At the end of the third pulse, a pulse is received from the pulse train of the navigation signal from the FCS 14 to the input input of the ECU 18, after which the ECU 18 generates a command to record the first delay code of the radio navigation signal pulse from the BFO 15 to the BCHOP 17 and increases by one the number of received delay codes η _i . Then, in the ECU 18, the condition η _i ≤ n = 6 is checked, where n is the length of the information package.

If η _i <6, then the procedure described above is repeated, providing a sequential record in BHOP 17 delay codes of the last six pulses from the pulse train of the navigation signal.

If η _i = 6, then the ECU 18 gives the command to transmit a combination of six delay codes from BHOP 17 to the input of the DB 19, where each such combination is associated with an a priori established combination of 1 = 7 binary bits, which is then written as a separate word of the received messages in the BHPS 20. Then, in the ECU 18, the number of received words of the message λ _{i is} increased by one, after which the ECU 18 sets the initial value of the number of received characters η _i = 0 and checks the condition λ _i ≤ λ ₀ = 30, where λ ₀ is the total the number of words, including the information part - 8 words - and correction codes.

If λ _i <30, then with the start of reception in receiver 2 of the next packet of pulses of the navigation signal from transmitter 1, the above procedure for receiving a word is repeated, and the number of the word recorded in BHPS 20 is set by the value N _i = λ _i-1 +1.
If λ _i = 30, which corresponds to the end of the reception of the complete message W in the prototype system, then the ECU 18 generates a command to transmit the entire received message from the BHPS 20 to the BCS 21, where, in accordance with the algorithms described, for example, in [10, p. . 185-209; 11, p. 315-337, 399-407], the detection and correction of errors in the received message. After the procedure for adjusting the message from BCS 21 to the ECU 18, a sign of the result of the correction (RK) is transmitted.

If RK = 1, which means either the absence of errors or the correction of all detected errors in the received message, then the ECU 18 generates a command, according to which the information part of the received message (P) - the first 8 seven-bit words - are written from BCS 21 to VBKh 22, and accompanies this command by writing to the VBKh 22 a sign of readiness of the message, after which in the ECU 18 the initial value λ _i = 0 is set and BHOP 17, BHPS 20 and BKS 21 are reset.

 If PK = -1, this means that the number of errors in the received message is greater than the correction codes transmitted in it can be corrected. In this case, all the procedures described in the previous paragraph are repeated, but the ECU 18 records in the VBH 22 a sign of an erroneous message reception.

 Then, the above-described procedures for receiving the next message are repeated.

 Thus, in the prototype system, due to modulation of the delay (phase) of the last six pulses in the packet of the radio navigation signal, the transmission and reception of information messages through the radio navigation channel of the IFRS are provided.

Moreover, as indicated in [6], high reliability of transmission is ensured with an average effective speed of V _av = 26.7 baud with losses for the implementation by the IFRNS users of the main navigation function: maximum - not more than 0.79 dB, average - not more than 0 , 41 dB, which corresponds to the average relative energy costs of the IFRNS signal for transmitting information 15.4 • 10 ^-3 dB / baud.

 Since the main purpose of the prototype system is to transmit to consumers messages with control and corrective information (CQI) when implementing the differential subsystem of the SRNS, the message format of 56 bits in the prototype system is unified with the ninth frame of RTCM messages [12].

However, in [12], the minimum recommended transmission rate is 50 baud, while the prototype system provides an average effective transmission rate (V _ex = 26.7 baud) of about 1.85 times less.

 In addition, the prototype system is focused on the transmission of only one message format with a fixed length (56 bits), while in [12] various message formats were recommended, the main one being a frame of the first type being a variable message long.

 The claimed invention is directed to solving the problem of transmitting information messages of variable length while increasing the transmission speed, at least to values that satisfy the recommendations [12].

 The essence of the invention lies in the fact that in a system for transmitting and receiving information messages via an IFRNS radio navigation channel containing a transmitter and a receiver, the transmitter comprises an antenna-transmitting device, the input of which setting pulses is connected to the output of the comparison unit, the first inputs of the bits of which are connected to the outputs of the corresponding bits of the counter, the input of clock pulses of which is connected to the first output of the driver of the reference signals, the second output of which is connected to the input of the recording pulses control code, the outputs of the bits of which are connected to the second inputs of the corresponding bits of the comparison unit, and the third output of the driver of the reference signals is connected to the input of the coding control unit, the information inputs and outputs of which are connected by the bus of information exchange with the information inputs and outputs of the encoding unit, the generator of correction codes , a message recording unit and an intermediate storage unit, the output of the control code of which is connected to the corresponding input of the control code register, In this case, the message input of the message recording unit is the information input of the transmitter, and the output of the navigation signals of the antenna-transmitting device is the output of the radio signals of the transmitter, which is connected by the radio navigation channel to the input of the radio signals of the receiver, which contains a clock signal generator whose input of the synchronization signal is connected to the output of the clock pulses of the receiver-converter devices whose signal strobe output is connected to the control input of the reference unit, info the mating inputs of which are connected to the outputs of the corresponding bits of the counter, the clock input of which is connected to the first clock output of the clock generator, the second clock output of which is connected to the input of the decoding control unit, whose information inputs and outputs are connected to the information inputs and outputs of the decoding unit , a received message storage unit, a message adjustment unit, an output storage unit and a packet sample storage unit, code input for which it is connected to the output of the readout unit, the input of the navigation signals of the receiving and converting device being the input of the radio signals of the receiver, and the message output of the output storage unit is the information output of the receiver, the control unit for generating the correcting codes and the unit for recording the number of message lines, information inputs are entered into the transmitter -the outputs of which are connected to the information exchange bus, and the message inputs of the message recording unit and the message line number recording unit are connected ezhdu themselves, thus introduced into the receiver storage unit line samples, the block selection start messages and messages correction control unit, data inputs and outputs of which are connected to the bus for information exchange.

 The invention, its feasibility, the possibility of industrial application and solving the technical problem are illustrated by the drawings, presented in FIG. 1 and 2, where in FIG. 1 shows a structural diagram of a prototype system, in FIG. 2 is a structural diagram of the inventive system.

 The inventive system for transmitting and receiving information messages over the radio-navigation channel IFRNS in this example implementation contains, see figure 2, the transmitter 1 and receiver 2. The transmitter 1 includes, as in the prototype system, an antenna-transmitting device (APU) 3 , a reference signal shaper (FOS) 4, a counter (MF) 5, a control code register (RCU) 6, a comparison unit (BS) 7, an intermediate storage unit (BPH) 8, an encoding unit (BC) 9, an encoding control unit (BUK) ) 10, the corrective code generator (FCC) 11 and the message recording unit (B C) 12. LES 12 Log messages is data input of the transmitter 1. Information inputs and outputs LES 12, CFC 11, 10 BUK, Wh BPH 9 and 8 are connected to the bus for information exchange. The output of the control code of BPH 8 is connected to the corresponding RCC 6, the outputs of the bits of which are connected to the second inputs of the corresponding bits of BS 7, the first inputs of the bits of which are connected to the outputs of the corresponding bits of SC 5, the input of the clock pulses of which is connected to the first output of FOS 4, the second and third outputs which are connected respectively to the input of the recording pulse RKU 6 and the driving input BUK 10. The output of the BS 7 is connected to the input of the driving pulses APU 3, the output of the navigation signals of which is the output of the radio signals of the transmitter 1.

 The composition of the receiver 2 includes, as in the prototype system, a receiving-converting device (PPU) 13, a clock signal shaper (FCS) 14, a sample forming unit (BFD) 15, a counter (MF) 16, a unit for storing sample readings (BHOP ) 17, the decoding control unit (ECU) 18, the decoding unit (OBD) 19, the received message storage unit (BHPS) 20, the message correction unit (BCS) 21 and the output storage unit (VBH) 22. The message output VBK 22 is an information output receiver. Information inputs and outputs VBH 22, BKS 21, BHPS 20, BD 19, BUD 18 and BHOP 17 are connected by an information exchange bus. The BHOP code input 17 is connected to the output of the BFD 15, the control input of which is connected to the output of the signal gate of the PPU 13, and the information inputs of the BFD 15 are connected to the outputs of the corresponding bits SCh 16. The clock input SCh 16 is connected to the first clock output of the FCS 14, the input of the synchronization signal of which connected to the clock output of the PPU 13, and the second clock output of the FCS 14 is connected to the control input of the ECU 18. The input of the navigation signals of the PPU 13 is the radio signal input of the receiver 2, which is connected by the radio navigation channel to the radio signal output Transmitter Fishing 1.

 In contrast to the prototype system in the inventive system, a control unit for generating corrective codes (BUFC) 23 and a unit for recording the number of message lines (BCHS) 24, information inputs and outputs of which are connected to the information exchange bus of transmitter 1, and a message input for BCHS are introduced into the transmitter 1 24 is connected to the message input of the BSS 12, and a string sample storage unit (BCHS) 25, a message start highlighting unit (BVN) 26 and a message correction control unit (BUKS) 27, the information input-outputs of which are connected to the information bus, are introduced into the receiver 2 receiver exchange 2.

 All elements of the inventive system can be implemented using standard or well-known blocks, devices, systems.

 As APU 3, FOS 4, MF 5, RKU 6 and BS 7 of the transmitter 1, the corresponding blocks of the modular transmitting station "Chaika UM" described in [7] can be used.

 The remaining functional blocks of transmitter 1 are BPH 8, BK 9, BUK 10, FKK11, BZS 12, BUFK 23 and BZChS 24 can be implemented using the computer of the central control panel [7] using the appropriate user programs as part of its mathematical software. Algorithms that implement the functions of the respective blocks are discussed below, when describing the operation of the claimed system.

 As PPU 13, FCS 14, BFO 15 and MF 16 of receiver 2, the corresponding functional blocks of the standard IFRNS indicator described, for example, in [13, p. 82 - 86] or in [14] can be used.

 The rest of the functional blocks of receiver 2 are BKHOP 17, BUD 18, BD 19, BHPS 20, BKS 21, VBKh 22, BHOS 25, BVN 26 and BUKS 27 can be implemented using the receiver-transmitter calculator [14] using the corresponding user programs as part of its software -math software. Algorithms that implement the functions of the respective blocks are discussed below, when describing the operation of the claimed system.

 Bus information exchange and the corresponding inputs and outputs of the functional blocks of the transmitter 1 and receiver 2 can be implemented in the form of a computer system bus type class ISA or PSA.

 The input of the control code RKU 6 and the corresponding output BPH 8, which defines the inputs of the BUK 10 and BUD 18, as well as the output of the BFD 15 and the code input of the BHOP 17 can be performed using an interface like S-232 or according to GOST 18977-79, or according to GOST 26765.52-87.

 The inputs of the messages BZS 12 and BZChS 24 and the output of messages VBH 22 can be implemented using standard COM ports of the RS-232 type.

 The inventive system operates as follows.

 In accordance with standard procedures described, for example, in [7], the transmitter 1 generates at its output of the radio signals periodically the following bursts of pulses of the navigation signal, which are transmitted via the radio navigation channel to the input of the radio signals of receiver 2.

The claimed system uses combinations with a zero sum of modulation indices within a row of four groups of six pulses (n = 24) based on a modulation code m = 5 and the value of the time shift between adjacent positions in the signal alphabet (minimum energy distance) d = 0, 7. Accordingly, the number of such combinations is A ₀ (5.24) ≈ 3.409 • 10 ¹⁵ , which allows one binary bit of information to be transmitted using one line of four packets of navigation pulses 51 (2 ⁵¹ <3.409 • 10 ¹⁵ ). In this regard, in the inventive system it is accepted that each information message (P) consists of λ _inf words with 51 binary bits each, total of λ _inf • 51 bits. Moreover, the number of words λ _inf = var, and each complete message (W) transmitted via the radio navigation channel contains the information part - P - and correction codes.

The message P to be transmitted is received at the information input of the transmitter 1 and is recorded (if there is write permission) in the BSS 12 in the form of a block of λ _inf 51-bit words. At the same time, the number of information words in the message λ _{inf is} recorded in the BCHS 24. The value λ _inf recorded in the BCHS 24 is transmitted to the BUK 10 and to the BUKF 23. In the BUK 10, a priori specified number of words of the complete transmitted message (W) λ _p is set according to this value , including information words (λ _inf ) and corrective codes (λ _k ). In BUFK 23, in accordance with the value of λ _p , an a priori defined command for controlling the structure of FCC 11 is established. This command is transmitted to FCC 11, where, in accordance with it, elements of FCC 11 are switched to generate correction codes in the amount of λ _k = λ _p -λ _inf corresponding to the number of words of the correction codes in the transmitted message. Then, by control commands from the BUK 10, the delay (phase) of the last six pulses in the pulse packets of the navigation signal of the transmitter 1 is modulated sequentially by each of the words of the transmitted message, for example, as follows.

From the third output of FOS 4, a pulse corresponding to the moment of the end of the second pulse from the pulse train of the navigation signal is supplied to the input input of the BUK 10. In BUK 10, the number of characters to be transmitted is set, η = n = 24, and a command is generated to transmit the first of λ _inf words from BSS 12 to FKK 11 and to FK 9. In FKK 11, it starts in accordance with the algorithms described, for example, in [10, p. 128-133, 224-231, 435-446; 11, p. 304-310, 391-398], the formation of correction codes. In BC 9, each word from 1 = 51 binary bits is associated with an a priori established combination of n • q = 72 binary bits, where n = 24 is the number of characters (pulses modulated by information delay) modulated by the base code m = 5, q = 3 - three bits describing the state of each of the n characters in the quaternary system (-2, -1, 0, 1, 2). From BC 9, a combination of n • q characters is recorded in BPH 8.

From the second and third outputs of FOS 4, the following pulses are received at the input of the write pulse of RKU 6 and the driving input of BUK 10, according to which the first three bits of n triples are copied from the output of the BPK 8 control code to RKU 6. In the BUK 10, the number decreases symbols η ,, to be transmitted, and the condition η _i = 0 is checked. For η ₁ > 0. BEECH 10 generates a shift command in BPH 8 of the three-bit combination recorded in it, preparing the modulation of the next pulse of the navigation signal. At the same time, the control code recorded in RKU 6 is sent to the second inputs of the corresponding bits of BS 7, where it is compared with the current state of the corresponding bits of SCh 5, to the clock input of which pulses from FOS 4 are received, providing a counting period of SCh 5 equal to the pulse repetition interval in the pulse train transmitter navigation signal 1. When the states of the corresponding discharges MF 5 and RKU 6 coincide, BS 7 generates pulses arriving at the input of the driving pulses APU 3, which generates a navigation signal at its output the next impulse from the pulse train of the navigation signal of transmitter 1 is caught. In this case, a change in the state of q bits of the ECG 6 provides a shift in the moment of formation of the next impulse in the control unit 3 with a step of 0.7 μs within ± 1.4 μs.

 Thus, one character is transmitted.

 Then, the symbol transmission procedure described above is repeated, providing a sequential transmission of six modulated pulses to the radio navigation channel.

When the condition η _i = 18, 12, 6, 0 is fulfilled, BUK 10 transmits to BPH 8 a command to set at its output a control code of the initial code corresponding to the unbiased state of the pulse in the pulse train of the navigation signal, which is rewritten to RKU by the next pulse from FOS 4 6, after which FOS 4 stops issuing pulses: to the SCh 5 clock input until the formation of the next burst of pulses of the navigation signal, and to the RKU 6 recording input and the BUK 10 input, until the formation of the second pulse of the next burst. When the condition η _i = 0 is fulfilled, which corresponds to the end of the transmission of a string of 24 characters (binary word of 51 bits), BEECH 10 increases by one the number of transmitted words installed in it (λ _i ). Then, in BUK 10, successive checks are carried out to satisfy the conditions λ _i ≤ λ _inf and λ _i ≤ λ _p , where λ _p is the total number of transmitted words in the inventive system, including the actual information message and correcting codes.

If λ _i <λ _inf , then when resuming the arrival of pulses from FOS 4 to the input BUK 10, the entire procedure for transmitting the word described above is repeated, and each time the word from message P, the number of which is set, is transmitted from BSS 12 to FKK 11 and to BK 9 the value of N _i = λ _i-1 +1.
If λ _i = λ _inf , which corresponds to the end of the transmission of the information part of the message W from λ _inf words, then when the impulses from FOS 4 to the BUK 10 are resumed, the word transfer procedure is repeated, but the word transmission from the BSS 12 to the FCC 11 and to the BC 9 is stopped and FKK 11 at the command of the BUK 10 is transferred from the mode of generating corrective codes to the mode of word-by-word transmission of these codes to BC 9.

If λ _i = λ _p , then BUK 10 gives a command to reset FCK 11, BZCHS 24 and BUFK 23, sets the value λ = 0 and sends permission to write the next message to BZK 12, after which the procedure for transmitting the next message described above is repeated.

 The bursts of pulses of the navigation signal, in each of which the six last pulses are modulated by the delay (phase) in this way by an information message, from the output of the radio signals of the transmitter 1 via the radio navigation channel are received through the input of the radio signals of the receiver 2 to the input of the navigation signal PPU 13, which, in accordance with the algorithms, described, for example, in [9, p. 121-142], it detects and tracks the received signal.

 At the same time, video pulses are generated at the output of the signal gate of the PPU 13, corresponding to the moments of receiving at the receiver 2 the marker position of each individual pulse from the pulse train of the navigation signal of the transmitter 1, and video pulses are formed at the output of the synchronization pulses of the PPU 13, which track the average values of the moments of reception of marker positions averaged over the tracking interval radio pulses of the navigation signal of the transmitter 1 and, therefore, synchronized with the period and moments of the beginning of reception in the receiver of 2 packs of radio pulses of the navigation signal of the transmitter 1. The marker position refers to a priori defined position in each pulse of the navigation signal of the transmitter 1, at which the radio navigation parameter is counted in the receiver 2.

 The video pulses from the output of the clock pulses of the PPU 13 are fed to the input of the FCS clock signal 14, which generates clock pulses synchronized with these video pulses at the first clock output, which are fed to the clock input of the SCh 16 and provide the formation of the counting period of the SCh 16, synchronous and common-mode with the average reception times the receiver 2 marker positions of the pulses of the navigation signal of the transmitter 1. A cyclically changing code from the outputs of the corresponding bits MF 16 is fed to the information inputs of the BFO 15, in torus at receipt on its control input of a video signal output from the PPU 13 is fixed strobe current state of respective bits Cq 16.

 At the same time, a countdown is formed at the output of BFO 15, proportional to the delay (-1.4; -0.7; 0; +0.7; +1.4) μs of a specific pulse from the packet relative to the moments of reception of pulses of the navigation signal averaged over the tracking interval transmitter 1.

 Then, according to the control commands from the ECU 18, the received message is decoded, the errors in the received message are selected and corrected, and the information part of the message is recorded, for example, as follows.

At the end of the third pulse, a pulse is received from the pulse train of the navigation signal from the FCS 14 to the input input of the ECU 18, after which the ECU 18 generates a command to record the first delay code of the radio navigation signal pulse from the BFO 15 to the BCHOP 17 and increases by one the number of received delay codes η _i . Then, in the ECU 18, the condition η _i ≤ n = 24 is checked, where n is the string length in the inventive system.

If η _i <6, 12, 18, 24, then the procedure described above is repeated, providing sequential recording in the BHOP 17 delay codes of the last six pulses from the pulse train of the navigation signal.

If η _i = 6, 12, 18, 24, then the ECU 18 gives the command to transmit combinations of six delay codes from BHOP 17 to BHOS 25, where a combination of delay codes for navigation pulses is sequentially generated within one line of four packages (packs) of six pulses in each.

If η _i = 24, then the ECU 18 gives a command to transmit a combination of delay codes from BHOS 25 to the input of the OBD 19, where each such line is associated with an a priori established combination (word) of 1 = 51 binary bits. The resulting word is transmitted to BVN 26, where it is analyzed to detect the preamble at the beginning of the word — a special code message with which, in accordance with [12], each informational message begins.

If the preamble is not found, then the sign of this is transmitted from the BVN 26 to the ECU 18, where in this case the value η _i = 18 is set and a command is generated in the BHOS 25, according to which six delay codes received first are erased in the BHOS 25, the remaining codes are shifted accordingly six positions to the right, after which the above-described procedures for receiving the delay codes of the last six pulses from the next burst of pulses of the navigation signal, forming the word in BHOS 25 and detecting the preamble are repeated.

If a preamble is found, then in the BVN 26 the procedure is performed for extracting the number of information words of the message λ _inf , which, in accordance with [12], is transmitted in the first word of each message, after which the detection sign of the preamble and the value of λ _inf are transmitted from the BVN 26 to the ECU 18 and BUKS 27. In the BUDS 18, in accordance with this value, an a priori specified number of words of the complete transmitted message λ _p = λ _inf + λ _{k is established} , including information words and correction codes. In BUKS 27 in accordance with the value of λ is set a priori defined _inf control command BCS structure 21.

This command is transmitted to BCS 21, where, in accordance with it, the elements are switched to ensure detection and correction of errors in the transmitted message with a volume of λ _p words. Then, the ECU 18 increases by one the number of received words of the message λ _i and gives the command to transmit the word of the received message from the BHOS 25 to the BHPS 20, after which the ECU 18 sets the initial value of the number of received symbols η _i = 0 and checks the condition λ _i ≤ λ _p .
If λ _i <λ _p , then with the start of reception in receiver 2 of the next packet of pulses of the navigation signal from transmitter 1, the above procedure for receiving a word and writing it to the BHPS 20, excluding the search and detection algorithm for the preamble, is repeated, and the number of the word recorded in the BHPS 20 is set by the value of N _i = λ _i-1 +1.
If λ _i = λ _p , then corresponds to the end of reception of the complete message W in the claimed system, then the ECU 18 generates a command to transmit the entire received message from the BHPS 20 to the BCS 21, where in accordance with the algorithms described, for example, in [10, p. . 185-209; 11, p. 315-337, p. 399-407], the detection and correction of errors in the received message. After the procedure for adjusting the message from BCS 21 to the ECU 18, a sign of the result of the correction (RK) is transmitted.

If RK = 1, which means either the absence of errors or the correction of all detected errors in the received message, then the ECU 18 generates a command by which the information part of the received message (P) - the first λ _inf words - are written from BCS 21 to VBKh 22, and accompanies this command by writing to the VBKh 22 the message ready sign, after which in the ECU 18 the initial value λ _i = 0 is set and BHOP 17, BHPS 20, BKS 21 and BHOS 25 are reset.

 If PK = -1, this means that the number of errors in the received message is greater than the correction codes transmitted in it can be corrected. Then, all the procedures described in the previous paragraph are repeated, but the ECU 18 records in the VBH 22 a sign of erroneous reception of the message.

 Then, the above-described procedures for receiving the next message are repeated.

 Thus, in the inventive system due to modulation of the delay (phase) of the last six pulses in the pulse train of the navigation signal, the transmission and reception of information messages via the radio navigation channel IFRNS is provided.

Moreover, the average effective information transfer rate in the inventive system (V _z.s. ) due to the use of variable length messages, the base of the modulation code m = 5 and the length of the information packet n = 24 when transmitting messages is increased compared to the prototype system (V _ave. ) ξ _Σ = (2.77 - 5.96) times.

 To confirm this effect, let us consider in more detail the principles of organizing the transmission of information messages in the claimed system.

The initial premises in the formation of the prototype system were the following requirements:
- ensuring high reliability and reliability of the transmission of CCI to all consumers in the working area of a specific differential GPS subsystem;
- preservation of blinking (flickering) of the first two pulses from the LORAN-C packet;
- minimization of quality loss of navigation definitions by the consumer using IFRNS indicators for them.

 Based on the conditions for the preservation of these requirements and the practical implementation of the principle of temporary (phase) manipulation of the last six pulses of the packet of the navigation signal, we consider ways to increase the transmission speed of the KKI over the IFRS radio navigation channel using the following assumptions.

 First, while maintaining the general principle of the implementation in each word of n pulses of combinations with zero sum of modulation indices, we consider the use of words longer than six.

 Secondly, while maintaining the principle of using small modulation coefficients, we consider the application of modulation codes with a base of more than three.

причем a₀ может отсутствовать (четные m = 2М) или присутствовать (нечетные m = 2М +1),
n - длина строки,
m - основание кода модуляции,
a_k - число повторений символа k в строке.To determine the volumes of binary combinations transmitted by strings with zero sum of modulation indices for an arbitrary base of the modulation code and an arbitrary string length, we consider the following combinatorial problem: determine the total number of sets of integers {a _-M , Λ, a _{+ M} } satisfying the constraints:

moreover, a ₀ may be absent (even m = 2M) or present (odd m = 2M +1),
n is the length of the string,
m is the base of the modulation code,
a _k is the number of repetitions of the character k in the string.

строк.For a given collection {a _-M , Λ, a _{+ M} } there exists

lines.

Сумма распространяется по всем наборам при выполнении (1).The total number of rows satisfying condition (1) will be

The amount is distributed over all sets when (1) is fulfilled.

Не трудно видеть, что она совпадает с (2). Выражение (3) легко преобразуется к виду

Заменой t _→ e^iθ (4) приводится к виду

Эти интегралы с высокой степенью точности вычисляются численными методами при умеренных m и n (по функциям трапеций).We introduce the complex variables z and t and consider the formal sum

It is not difficult to see that it coincides with (2). Expression (3) is easily converted to

By substituting t _ → e ^iθ (4), we ^obtain

These integrals are calculated with a high degree of accuracy by numerical methods for moderate m and n (according to the trapezoid functions).

Рассмотрим поведение скорости передачи информации:

где 1^(m,n) - число двоичных бит информации, передаваемых одной строкой при соответствующих m и n.For large n, we give the asymptotics

Consider the behavior of the information transfer rate:

where 1 ^{(m, n)} is the number of binary bits of information transmitted by one line for the corresponding m and n.

При умеренных n рассмотрим отношение скоростей V(m₁,n)/V(m₂,n) для различных пар m₁ и m₂. Из (7) видно, что скорость передачи информации, во-первых, с ростом n стремится к постоянной, зависящей от основания кода модуляции (при этом выигрыш при переходе к большим n уменьшается с ростом n), и, во-вторых, скорость возрастает с увеличением основания кода модуляции при больших n по логарифмическому закону, поэтому и здесь выигрыш будет падать" с ростом основания кода модуляции. Соответствующие результаты сведены в таблицу 1 (представлена ниже), где V(3,6) - скорость передачи информации в системе-прототипе.It is clear from the asymptotics that

For moderate n, we consider the ratio of the velocities V (m ₁ , n) / V (m ₂ , n) for different pairs of m ₁ and m ₂ . It can be seen from (7) that the information transfer rate, firstly, with increasing n tends to a constant depending on the base of the modulation code (in this case, the gain in going to large n decreases with increasing n), and secondly, the speed increases with an increase in the base of the modulation code for large n according to the logarithmic law, therefore, here the gain will fall "with an increase in the base of the modulation code. The corresponding results are summarized in table 1 (presented below), where V (3,6) is the information transfer rate in the system prototype.

 From table 1 it is seen that a significant gain in the information transfer rate is provided with an increase in m and n only in the region of relatively small m ≤ 6 and n ≤ 30.

 As mentioned above, the average effective transmission rate in the prototype system (26.7 bit / s) is approximately 1.85 times less than the minimum acceptable according to the RTCM recommendations, the effective transmission rate of the CRP is 50 bit / s. From the analysis it follows that the minimum allowable effective transmission rate for m = 4 is not achieved within the scope of the review, for m = 5 it is provided for n = 24 and for m = 6 it is provided for n = 12.

где Δφ_cp - среднее смещение фазы несущей импульса сигнала ИФРНС за счет модуляции.Taking into account the obtained estimates of the effective transmission speed of the CRP, we consider the loss for the radionavigation function when modulating by a temporary (phase) shift six pulses of the IFRNS signal burst based on the modulation code m = 5, 6. With a line length of n _o = 6, the losses will be determined by a decrease in the transconductance in reference point of the radio navigation parameter and can be described by the expression

where Δφ _cp is the average phase shift of the carrier pulse of the IFRNS signal due to modulation.

Table 2 (presented below) shows H _s from (8) for m = 5, 6 for various resolution bases d, which determine the magnitude of the time shift between adjacent positions in the signal alphabet (minimum energy distance).

For comparison, we indicate that for the prototype system (d = 1 μs, m = 3) H _s ≈ 0.41 dB.

When using strings with a zero sum of modulation indices of length n = μn ₀ , where μ = 1, 2, ..., for transmitting the CQI, additional losses occur due to random biases of the RNP count, firstly, due to the non-repeated averaging interval in the receiver indicator IFRNS line duration and, secondly, due to the asynchrony of the moments of formation of the RNP reference from the beginning of the line.

где σ_пи - СКО единичных измерений РНП в приемоиндикаторе ИФРНС при отсутствии информационной модуляции,

Δ_max - максимальное смещение импульса сигнала ИФРНС за счет модуляции,
c = T_сгл•T_сл ^-1,
T_сгл - постоянная времени измерителя РНП в приемоиндикаторе ИФРНС,
T_сл ^-1 - период следования пачек импульсов сигнала ИФРНС.To a first approximation, these losses can be defined as

where σ _pi is the standard deviation of single measurements of RNP in the IFRNS indicator in the absence of information modulation,

Δ _max - the maximum shift of the pulse of the IFRNS signal due to modulation,
c = T _smg • T _sl ^-1 ,
T _sgl - time constant of the RNP meter in the IFRNS indicator,
T _SL ^-1 - the period of the following bursts of pulses of the signal IFRNS.

Table 3 (presented below) shows the values of σ _cm and H _cm at d = 0.8; 0.7; 0.6 μs and typical for modern transceivers σ _pi ≈ 50 ns and s = 40 for positions in which the minimum permissible effective transmission speed of the CCS is achieved: m = 5, n = 24 and m = 6, n = 12.

Accordingly, the total losses for the radionavigation function due to the use of the IFRNS signal for transmitting information using strings of length n> 6 will be determined as
H _Σ = H _s + H _see (eleven)
From the analysis of the data given in table. 2 and tab. 3, it can be seen that the minimum admissible effective transmission rate is ensured for equal d at m = 5 and n = 24 with less losses than at m = 6 and n = 12.

Table 4 (presented below) shows the values of H _Σ for m / n = 5/24 and m / n = 6/12 for d = 0.7 and 0.6.

где W - коэффициент затухания, который для S ≈ 600 км над типовой сушей равен [13, стр.41-43] W₆₀₀ ≈0,45.Consider the probability of an error in the reception of a single package P ₀ at d = 0.7; 0.6 for a special case of receiving CQI at a distance of 600 km from the IFRNS station, which approximately corresponds to the typical boundary of the working area of the differential subsystem of the SRNS. The radiation power of the transmitting station is assumed to be equal to P _rad = 150 kW, which corresponds to the minimum radiated power of the IFRNS Chaika and LORAN-C stations. Then, at the distance S, the field strength of the useful signal is [9, p. 208, 209]

where W is the attenuation coefficient, which for S ≈ 600 km above a typical land is [13, p. 41-43] W ₆₀₀ ≈0.45.

Затем, используя типовое для диапазона ИФРНС f= 100 кГц значение напряженности поля атмосферных шумов [15, стр. 108] в полосе Δf = 28 кГц Е_шАТМ ≈0,2 мВ>/м, получим среднее значение отношения сигнал/шум в точке приема сигнала:

Согласно [16] для случая различения фазоманипулированных сигналов

где Φ - интеграл вероятности,
φ_M - разность фаз различаемых сигналов.Then, substituting in (12) the corresponding values of P _rad in kW and S in km, we obtain

Then, using the atmospheric noise field strength typical for the IFRNS range f = 100 kHz [15, p. 108] in the band Δf = 28 kHz E _wATM ≈0.2 mV> / m, we obtain the average signal-to-noise ratio at the receiving point signal:

According to [16], for the case of distinguishing phase-shifted signals

where Φ is the probability integral,
φ _M is the phase difference of the distinguished signals.

For d = 0.7 and d = 0.6, we obtain, respectively
P ₀ ^(0.7) ≈1.3 • 10 ^-5 , (16)
P ₀ ^(0.6) ≈1.4 • 10 ^-4 , (17)
Given the subsequent increase in the reliability of the transmission of CQI through the use, as is done in the prototype system, corrective codes such as Reed-Solomon and P ₀ ^(0.7) , and P ₀ ^(0.6) are satisfactory. But, given the possibility of providing an increase in the zone of the differential subsystem of the SRNS, one can give preference to the use of modulation with d = 0.7 μs. In this case, the relative losses in the signal energy during the implementation of the navigation function due to the use of the radio navigation signal to transmit information will be equal to: in the prototype system - 15.4 • 10 ^-3 dB / baud, in the inventive system - 14.2 • 10 ^-3 dB / baud

Moreover, in accordance with (5) and the data in Table. 1, the average effective data transmission speed in the inventive system (V _ZS) by providing transmission modulation code information base m = 5 and n = length of line 24 is increased in comparison with the prototype system (V _pr) in
ξ1 ≈ 1.82 (times). (18)
As mentioned above, the main purpose of the system under consideration is the transmission of messages from CCI to consumers during the implementation of the differential SRNS subsystem.

 Moreover, as follows from the description of its work, the claimed system, in contrast to the prototype system, provides the transmission and reception of messages of variable length. This allows you to use in the inventive system for transmitting a CCI not a rigidly defined frame of 56 bits, as in the prototype system, but a frame of variable length corresponding to the frame of the first type recommended in [12].

 The implementation of the differential subsystem of the SRNS requires the transmission of the spacecraft monitoring system over all spacecraft (spacecraft) of the space monitoring system, visible from the position of the transmitter. According to, for example, [17], the average number of simultaneously visible spacecraft when working on one of the two existing SRNSs (GPS and GLONASS) is 8.

Thus, in the case of use in the prototype system for transmitting UCI for each individual message spacecraft rigidly predetermined length (56 bits) for transmission over 8 SC information need l _ave. = 56 x 8 = 448 bits. If for the same purposes we use a message of variable length, similar to the first type of frame [12], then we will need to transmit along with the message header, including according to [12], including the preamble and the number of information words of the message, l _z.s. = (48 + 40 x 8) = 368 bits. All things being equal, this provides a reduction in the time required to transmit a given amount of information, which is equivalent to an increase in V _s.s. compared with V _ave. in
ξ ₂ = l _pr / l _s.c ≈ 1.23 (times) (19)
Due to the fact that the claimed system, unlike the prototype system provides the transmission of messages of variable length (λ _p = var), a closer look at the choice of the number of words _in lambda depending on the number of words lambda _inf. At the same time, as in the prototype system, we use Reed-Solomon cyclic codes as correcting ones, since they have the least redundancy and practically implementable schemes of encoders and decoders have been developed for them [11, pp. 391–407].

When using the inventive system for its main purpose, that is, for transmitting CCI in the differential subsystem of the SRNS, the most stringent requirements for the reliability of message transmission are imposed in the case (limiting for operation under conditions of restrictions [12]) of aircraft landing in the 1st category. In particular, according to [18], the probability of an error in transmitting a CCI in this case should not exceed
P _Osh ≤P _add = 3.3 • 10 ^-7 . (20)
According to [17], the number of simultaneously visible SRNS SCs varies from 4 to 10. Therefore, the amount of information transmitted in a message corresponding to a frame of the first type [12] varies from l ₄ = 40 x 4 + 48 = 188 bits to l ₁₀ = 40 x 10 + 48 = 448 bits. In the inventive system for the transfer of such volumes of information will require λ _inf = 4 - 9 words. In addition, [12] provides for the use of other message frames with a volume of (60 - 150) bits, for the transmission of which in the inventive system it is required to use λ _inf ≥ 2 words. Therefore, in the subsequent analysis, we consider the values of λ _p that ensure the transmission of both 2 ≤ λ _inf ≤ 10 words and the corresponding values of λ _to words for which condition (20) is fulfilled for this message.

То есть, ошибки приема сообщения после его коррекции в БКС 12 заявляемой системы будут иметь место тогда, когда кратность ошибок превысит К. Соответственно, вероятность такой ситуации при приеме сообщений длиной λ_p слов будет равна [19]

В таблице 5 (представлена ниже) приведены значения P_ош(λ_p, k) при λ_p = 4-15 и k = 1-4.Each word in the inventive system is transmitted in a line of 24 pulses. In accordance with (16), the probability of an erroneous reception of one pulse is P ₀ ≤ 1.3 • 10 ^-5 . Then the probability of error when receiving one line of 24 pulses will be equal to [19, p. 444]
P _c = 1- (1-P ₀ ) ²⁴ ≈3.12 • 10 ^-4 . (21)
When receiving messages containing Reed-Solomon correcting codes, all erroneously received words will be corrected, provided that the number of such words (error rate) does not exceed [10, 11]

That is, errors in receiving a message after correction in BCS 12 of the claimed system will occur when the error rate exceeds K. Accordingly, the probability of such a situation when receiving messages with a length of λ _p words will be equal to [19]

Table 5 (presented below) shows the values of P _Ош (λ _p , k) for λ _p = 4-15 and k = 1-4.

From the analysis of the data table. 5, taking into account (22), it follows that when transmitting λ _inf = 2-10 words, condition (20) is satisfied if λ _k and λ _{p are} not less than the values given in table 6 (presented below).

In the fourth row of the table. 6 shows the values of V _{C. S.} when transmitting messages with a length of λ _p words. The fifth row also contains the values of the overall coefficient of increase in the average effective information transfer rate in the inventive system with respect to the prototype system (ξ _Σ ).
From the analysis of the data table. 5 and tab. 6 it follows that the claimed system, in contrast to the prototype system in all cases provides, with the necessary reliability, an effective information transfer rate that meets the recommendations [12]. At the same time, with respect to the prototype system, the information transfer rate increases by ξ _Σ = (2.77 - 5.96) times.

 Thus, the introduction of new blocks and new connections between them in the inventive system ensures the transmission of messages of variable length while increasing the effective information transfer rate to values that satisfy the recommendations [12].

 The combination of these positive features of the claimed system provides the expansion of opportunities for its use, the transmission of messages of variable length and increase the speed of information transfer.

 From the review it is clear that the claimed system is technically feasible, solves the tasks and can find application in the differential subsystems of the SRNS, in communication systems, in transmission systems of telemetric information, etc.

SOURCES OF INFORMATION
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 11. Peterson W., Weldon E. Codes for correcting errors. - M .: "World", 1976.

 12. RTCM Recommendet Standards for Differential NAVSTAR GPS Service. Version 2.2, January 3,1996.

 13. Bykov V.I., Nikitenko Yu.I. Ship radio navigation devices. - M .: "Transport", 1976.

 14. Frank P.L. Modern developments on the LORAN-S system // TIIER, vol. 71, N10, October 1983, pp. 8-23 / Per. from English M .: "World".

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 17. Lowe D., Walsh D., Capaccio St., Daly P. et al. Real time differential positioning of aircraft using GPS and GLONASS // Proc. ION - 96, 19-21 Yune, 1996.

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Claims (1)

 A system for transmitting and receiving information messages on the radio navigation channel of a pulse-phase radio navigation system, comprising a transmitter and a receiver, the transmitter comprising an antenna-transmitting device, the input of which is set to the output of the comparison unit, the first inputs of the bits of which are connected to the outputs of the corresponding bits of the counter, the input clock pulses which is connected to the first output of the reference signal shaper, the second output of which is connected to the input of the register write pulses to a control ode, the outputs of the bits of which are connected to the second inputs of the corresponding bits of the comparison unit, and the third output of the driver of the reference signals is connected to the master input of the coding control unit, the information inputs and outputs of which are connected by the information exchange bus to the information inputs and outputs of the coding unit, the generator of correction codes, a message recording unit and an intermediate storage unit, the output of the control code of which is connected to the corresponding input of the control code register, m the message input of the message recording unit is the information input of the transmitter, and the output of the navigation signals of the antenna-transmitting device is the output of the radio signals of the transmitter, which is connected by the radio navigation channel to the input of the radio signals of the receiver, which contains a clock shaper, the input of the synchronization signal of which is connected to the output of the clock pulses of the receiver-converter devices, the output of the signal strobe of which is connected to the control input of the reference unit, information whose inputs are connected to the outputs of the corresponding bits of the counter, the clock input of which is connected to the first clock output of the clock generator, the second clock output of which is connected to the input of the decoding control unit, whose information inputs and outputs are connected to the information inputs and outputs of the decoding unit , a received message storage unit, a message adjustment unit, an output storage unit, and a packet sample storage unit, a code input to It is connected to the output of the readout unit, the input of the navigation signals of the receiver-converter device being the input of the radio signals of the receiver, and the message output of the output storage unit is the information output of the receiver, characterized in that a control unit for generating corrective codes and a unit for recording the number of message lines are entered into the transmitter the information inputs and outputs of which are connected to the information exchange bus, and the message inputs of the message recording unit and the message line number recording unit The communications are interconnected, while the receiver contains a block for storing the samples of the line, a block for allocating the beginning of the message, and a block for controlling the correction of messages, the information inputs and outputs of which are connected to the data exchange bus.

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