CN110687561A - Hidden satellite navigation positioning system - Google Patents
Hidden satellite navigation positioning system Download PDFInfo
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- CN110687561A CN110687561A CN201911125855.6A CN201911125855A CN110687561A CN 110687561 A CN110687561 A CN 110687561A CN 201911125855 A CN201911125855 A CN 201911125855A CN 110687561 A CN110687561 A CN 110687561A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/421—Determining position by combining or switching between position solutions or signals derived from different satellite radio beacon positioning systems; by combining or switching between position solutions or signals derived from different modes of operation in a single system
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
Abstract
A hidden satellite navigation positioning system comprises a hidden satellite constellation, a hidden navigation positioning signal, a hidden navigation positioning ground main control station, an intelligent receiver and a passive orbit determination station; the hidden satellite constellation is a universal GEO communication satellite constellation and consists of a C/Ku frequency band GEO commercial communication satellite, an SIGSO small-inclination angle synchronous orbit satellite and an IGSO inclined orbit satellite; the hidden navigation positioning signal is hidden under the original service signal of the generic GEO communication satellite, the signal power is less than one percent of the full load power of a satellite transponder, the bandwidth of the navigation signal is more than 40MHz, and the reduction amplitude of the signal-to-noise ratio of the original signal is not more than 0.3 dB; the hidden navigation positioning ground main control station is a fixedly arranged hidden navigation positioning fixed station or a hidden navigation positioning vehicle-mounted static through station capable of moving along with a vehicle; the intelligent receiver comprises an antenna module, a radio frequency module, a baseband processor module and an autonomous navigation module; the passive orbit determination station comprises at least four orbit determination reference stations positioned on the earth surface, a receiver of the orbit determination reference station collects satellite signals, the position correction quantity of the measured satellite is calculated, the orbit determination precision is counted, the satellite position correction quantity information is arranged in a navigation message, and the satellite is injected into the ground main control station through hidden navigation positioning for a user to use when the user positions.
Description
Technical Field
The invention belongs to the field of satellite navigation, and particularly relates to a hidden satellite navigation positioning system.
Background
Currently, the satellite navigation technology is developed, such as GPS in the united states, GLONASS in surussia, Galileo in europe, and beidou satellite navigation system (BDS) in china. In addition to the four major global navigation systems, many countries are developing their own regional positioning systems, including QZSS, japan and IRNSS, india. The system is largely the same as or different from the GPS, and has no essential difference. The GPS with extremely strong effect is extremely susceptible to interference. The satellite signal is attenuated by a path of approximately 2 ten thousand kilometers and the power reaching the ground is extremely weak (of the order of only 10-16 watts). In particular, GPS is only split into 3 narrow fixed L-bands in the International Telecommunications Union (ITU). During the period of the Meisu confrontation, Su Russian finds that the GPS is very easy to interfere, and develops an inexpensive GPS jammer to compete with the Meisu. And forgo GLONASS as the top priority system for military deployment. GPS has had many tragic failures in confrontation and war: (1) in the second gulf war, iraq bought a GPS jammer from Russia to induce a plurality of army precision guidance missiles to deviate from the orbit; (2) in 2011 iran declared capture of the united states "sentinel" unmanned aerial vehicle and stated that passwords were mastered. In fact, the islander uses the GPS jammer to cause the unmanned aerial vehicle to fall down and pick up the unmanned aerial vehicle; (3) the GPS jammer is deployed in 'three-eight lines' in Korea, so that the large-scale GPS in Hancheng fails. The united states Defense Advanced Research Program Agency (DARPA) points out: GPS is revolutionary, however it also has limitations. GPS signals cannot be received underground, underwater, and signals are significantly degraded or even unusable during solar storms. Even more feared are interfering signals from the adversary. GPS is vital, but its limitations in some environments make it a fatal weakness if soldiers rely on GPS as the sole source of PNT (positioning, navigation and timing) information.
GPS-like systems are extremely vulnerable to interference. This vulnerability was discovered in the united states early in GPS development and is believed to be a common and inherent vulnerability of GPS and other similar navigation systems. The reasons for this weakness are: the GPS satellite has only a transmission power of several tens of watts, and the signal power reaching the ground is very weak through propagation over about twenty thousand kilometers. And the jammer is close to the ground receiving terminal, and the arrival power can be very high. Much more powerful than GPS, to the ground. And the deceptive interference is added, so that the GPS-like system is very easy to interfere.
The navigation positioning systems have the following characteristics: in order to realize miniaturization and convenient use of the positioning receiver, the antenna of the positioning receiver generally adopts an omnidirectional antenna, so that the positioning receiver can receive positioning signals of more than 4 satellites no matter how the attitude of the carrier changes. In order to ensure that the omnidirectional antenna can successfully receive signals of the satellite and ensure that the omnidirectional antenna has enough carrier-to-noise ratio, the power of signals transmitted by the satellite is about dozens of watts. And the orbit parameter of the used satellite, the working frequency used, and even the detail information such as the ranging code rate of the civil signal are all open and can be obtained. Even if the information is not disclosed, the satellite signals are received by an antenna with a larger caliber, the satellite signals can be received by a spectrum analyzer, and the working frequency points and the bandwidth of the signals can be easily acquired. These systems therefore suffer from the problem of being susceptible to interference in use.
Disclosure of Invention
In order to solve the problem that a satellite navigation system is easy to be identified and interfered, the invention aims to provide a hidden satellite navigation positioning system, the system does not need to transmit a special navigation satellite, but hides a navigation signal on a common communication satellite, the navigation positioning function is realized under the state that the system and the signal are hidden, the system is not easy to be found or interfered, and the hidden navigation positioning system can still normally work under the condition of fighting against enemies; in addition, the system can also realize three modes of changing stars, changing frequencies, changing codes and the like to actively avoid potential or existing interference, and has important military significance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a hidden satellite navigation positioning system comprises a hidden satellite constellation, a hidden navigation positioning signal, a hidden navigation positioning ground main control station, an intelligent receiver and a passive orbit determination station;
the hidden satellite constellation is a universal GEO communication satellite constellation and consists of a C/Ku frequency band GEO commercial communication satellite, an SIGSO small-inclination angle synchronous orbit satellite and an IGSO inclined orbit satellite, the working mode is that IGSO satellite navigation signal direct emission and GEO and SIGSO satellite forwarding are combined, the hidden navigation signal is sent to a user receiver, and the functions of positioning, time service, speed measurement and the like of the user receiver are realized;
the hidden navigation positioning signal is hidden under the original service signal of the generic GEO communication satellite, the signal power is less than one percent of the full load power of a satellite transponder, the bandwidth of the navigation signal is more than 40MHz, and the reduction amplitude of the signal-to-noise ratio of the original signal is not more than 0.3 dB;
the hidden navigation positioning ground main control station is a fixed hidden navigation positioning fixed station or a hidden navigation positioning vehicle-mounted static through station capable of moving along with a vehicle, and comprises an antenna system, radio frequency equipment, a hidden navigation signal comprehensive baseband, system time frequency generation and distribution equipment and a master control system, and is used for completing the generation, emission, reception, processing, monitoring and evaluation of hidden navigation signals of satellites in corresponding frequency bands, and synchronizing satellite-ground time and annotating information of the satellites;
the intelligent receiver comprises an antenna module, a radio frequency module, a baseband processor module and an autonomous navigation module, wherein the antenna module receives a navigation signal from a covert satellite constellation, the radio frequency module receives a covert navigation signal from the antenna module, the covert navigation signal is amplified by a low-noise amplifier and subjected to frequency conversion by a down converter and then is sent to the baseband processor module, the autonomous navigation module receives a signal from the baseband processor module, and when the system needs to switch a navigation mode, the autonomous navigation module is started to realize uninterrupted navigation;
the passive orbit determination station comprises at least four orbit determination reference stations positioned on the earth surface, a receiver of the orbit determination reference station collects satellite signals, the position correction quantity of the measured satellite is calculated, the orbit determination precision is counted, the satellite position correction quantity information is arranged in a navigation message, and the satellite is injected into the ground main control station through hidden navigation positioning for a user to use when the user positions.
The hidden navigation positioning ground main control station is a fixed set of hidden navigation positioning fixed stations, the number of the hidden navigation positioning fixed stations is about 8, and the aperture of the antenna is more than 3.7 meters.
The hidden navigation positioning ground master control station is a movable vehicle-mounted static center-through station, is loaded on a movable vehicle, is about 8 sets in number, and has the antenna aperture of about 2 meters.
The antenna module of the intelligent receiver adopts an anti-interference digital multi-beam electric scanning antenna, the antenna module is provided with more than 6 beams with adjustable pointing directions, and the maximum gain of each beam is 20 dBi.
And each high-precision ranging receiver corresponds to one satellite.
And the power of the hidden navigation positioning signal is one second hundredth of the full load power of the satellite transponder.
And the power of the hidden navigation positioning signal is one fourth percent of the full load power of the satellite transponder.
The technical scheme of the invention overcomes the technical problem that the existing satellite navigation system is easy to be interfered, and has the following advantages:
(1) the emission power of the hidden navigation signal is low: the concealed pilot signal power is 20dB lower than the full-load transmit power of the transponder (equivalent to occupying less than 1% of the transponder power).
(2) A wider band signal is used with higher spreading gain. The hidden navigation signal adopts the ranging code with the speed of 20Mcps and above, the signal bandwidth is 40MHz and above, the signal bandwidth is improved by 13dB compared with the GPS coarse code, and the signal bandwidth is improved by 3dB compared with the GPS fine code, so the anti-interference capability is stronger, and the ranging precision is higher.
(3) Communication satellites are utilized for free. The covert navigation signal can be hidden on a commercial communication satellite without transmitting a dedicated navigation satellite or renting or buying a satellite, and theoretically all transparent transponded communication satellites above the earth can be utilized by the covert navigation system. Therefore, the system investment is greatly reduced.
(4) The distance measurement precision of the hidden satellite navigation system can reach within 10 cm, the positioning precision of the hidden satellite navigation system can reach the sub-meter level, and the hidden satellite navigation system can be used for precision attack military operations such as missile guidance and the like.
(5) The system has very flexible functions of changing stars, changing frequency, changing codes and the like. When the situation that the satellite used by the system in a hidden way is interfered occurs, the system can select other satellites in proper positions to replace the satellites; if the originally concealed working frequency point is attacked maliciously, the system can be replaced by another working frequency point; if the original ranging code is interfered, the original ranging code can be replaced by other preselected ranging codes.
The conventional satellite navigation system is suitable for use scenes with low requirements on safety and reliability, and needs strong viability, anti-interference capability, stability and concealment for some special industries such as military application. The covert satellite navigation system can generate a broadband weak navigation signal with low power spectral density by using a ground main control station, realizes a covert navigation function by using repeaters of all visible communication satellites, and has an important application prospect. The method comprises the steps of generating a weak navigation signal of a broadband (40MHz and above) by using a ground navigation master control station, selecting and using a plurality of on-orbit communication satellites above the earth for transfer, wherein the power of the hidden navigation signal is more than 20dB lower than the full-load transmitting power of a transponder, the navigation signal reaching the transponder cannot interfere with the original communication service signal, and an intelligent receiver on the ground receives the weak navigation signal forwarded by 4 or more communication satellites to realize the functions of navigation and positioning.
The hidden navigation system based on the communication satellite realizes navigation and positioning by utilizing a commercial communication satellite, and a navigation signal of the hidden navigation system is transmitted by a ground navigation main control station and is forwarded to a navigation receiver through a satellite transponder. Because the navigation signal is generated on the ground instead of the traditional satellite, the navigation signal has the convenient conditions of satellite changing, frequency changing and code changing. This has obvious advantages for developing covert navigation. The hidden navigation technology has the characteristics of weak signals, low power spectral density and difficult discovery by enemies or other monitoring equipment, so that a positioning receiver with a high-gain self-adaptive navigation receiving antenna is needed. The method can be suitable for satellite frequency bands with abundant satellite resources such as C, Ku, Ka and the like.
Drawings
FIG. 1 is a schematic diagram of the working principle of the covert satellite navigation positioning system of the present invention;
FIG. 2 is a schematic diagram of the components of a covert satellite constellation of the present invention;
FIG. 3 is a schematic diagram of the hidden navigation positioning ground main control station of the present invention;
fig. 4 is a schematic diagram of the intelligent receiver according to the present invention.
The system comprises a hidden satellite constellation 1, a hidden navigation positioning signal 2, a hidden navigation positioning ground main control station 3, an intelligent receiver 4, a passive orbit determination station 5, an antenna system 6, a radio frequency device 7, a hidden navigation signal comprehensive baseband 8, a system time frequency generating and distributing device 9, a master control system 10, an antenna module 11, a radio frequency module 12, a baseband processor module 13 and an autonomous navigation module 14.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention aims to provide a covert satellite navigation positioning system with excellent anti-interference characteristic. Referring to fig. 1, the system comprises a covert satellite constellation 1, a covert navigation positioning signal 2, a covert navigation positioning ground main control station 3, an intelligent receiver 4 and a passive orbit determination station 5.
Referring to fig. 2, the covert satellite constellation 1 is a generic GEO communication satellite constellation, and is composed of a C/Ku frequency band GEO commercial communication satellite, an SIGSO small-inclination angle synchronous orbit satellite and an IGSO inclined orbit satellite, and the working mode is that the IGSO satellite navigation signal is directly transmitted and the GEO and SIGSO satellite are transmitted and combined, and the covert navigation signal is directly transmitted or transmitted to a user receiver, so that the functions of positioning, time service, speed measurement and the like of the user receiver are realized.
The hidden navigation positioning signal 2 is hidden under the generic GEO satellite original service signal, the navigation signal power is one percent or less, preferably one two percent or more preferably one four percent of the full load power of a satellite transponder, the bandwidth of the navigation signal reaches more than 40MHz, the power spectral density is very low, and the reduction amplitude of the signal-to-noise ratio of the original signal is caused to be not more than 0.3 dB.
Referring to fig. 3, the hidden navigation positioning ground main control station 3 may be a fixed hidden navigation positioning fixed station, or may be a hidden navigation positioning vehicle-mounted stationary-center communication station capable of moving along with a vehicle, and includes an antenna system 6 (including a servo control system), a radio frequency device 7 (including a high power amplifier, a low noise amplifier, an up converter, a down converter), a hidden navigation signal comprehensive baseband 8, a system time frequency generating and distributing device 9 and a master control system 10, for completing generation, transmission, reception, processing, monitoring and evaluation of a satellite hidden navigation signal of a corresponding frequency band, and completing satellite-ground time synchronization and information uploading of the satellite.
The hidden navigation signal comprehensive baseband 8 edits and generates navigation messages, and encrypts and corrects the messages; meanwhile, the message is recovered, and the message to be sent and the message to be recovered are compared and verified; then, the generated navigation message is encoded, spread and modulated to generate various intermediate frequency signals, and the intermediate frequency signals are sent to a radio frequency channel to be subjected to up-conversion and amplification processing and then uplink to a corresponding satellite; and receiving a downlink navigation signal, amplifying the downlink navigation signal by a low noise amplifier, carrying out frequency conversion by a down converter, and sending the downlink navigation signal to a hidden navigation signal comprehensive baseband 8 for data processing such as despreading, demodulation, pseudorange and Doppler measurement, text analysis and the like.
The system time frequency generating and distributing device 9 generates a time frequency reference signal with high stability and high reliability, provides a system time and frequency signal which is traced to the national standard time UTC (NTSC) for the hidden navigation positioning ground main control station 3 and the passive orbit determination station 5, and realizes the synchronous operation of each station device in the system.
The master control system 10 completes centralized monitoring control of the working state of the hidden navigation positioning ground master control station 3, unified management of data and networks of the hidden navigation positioning ground master control station 3, and system decision of interaction, satellite changing, frequency changing and code changing of external data of the hidden navigation positioning ground master control station 3.
Referring to fig. 4, the intelligent receiver 4 includes an antenna module 11, a radio frequency module 12, a baseband processor module 13 and an autonomous navigation module 14, where the antenna module employs an anti-interference digital multi-beam electrically swept antenna and receives a navigation signal from a covert satellite constellation 1, and the radio frequency module 12 receives the covert navigation signal from the antenna module 11, amplifies the signal by a low noise amplifier, performs frequency conversion by a down converter, and sends the signal to the baseband processor module 13; the autonomous navigation module 14 receives the signal from the baseband processor module 13, and when the system needs to switch the navigation mode, the autonomous navigation module 14 is started to realize uninterrupted navigation. The autonomous navigation module 14 contains a barometric altimeter module and an atomic clock, and positioning can be realized by only two satellites even under the worst condition.
The anti-interference digital multi-beam electric scanning antenna module 11 directs each beam to a corresponding satellite according to a satellite constellation specified by a system, receives a hidden navigation signal from the corresponding satellite and amplifies the hidden navigation signal, has self-adaptive anti-interference capability, can form null in an interference incoming wave direction, and has inhibition capability on an interference signal; the radio frequency module 12 can automatically switch the working frequency point under the system control command. The baseband processor module 13 is used for capturing and tracking the hidden navigation positioning signal, and can switch the ranging code under the system control command. The autonomous navigation module 14 can achieve continuous switching of the escape, the escape frequency, and the escape within a short transition time (about 30 seconds).
The passive orbit determination station 5 comprises at least 4 orbit determination reference stations positioned on the surface of the earth, a receiver of the orbit determination reference station collects satellite signals, calculates the position correction quantity of the measured satellite, counts the orbit determination precision, arranges the satellite position correction quantity information into a navigation message, and injects the satellite into the ground main control station 3 through hidden navigation positioning for the user to use during positioning.
The working process of the hidden satellite positioning system is that the hidden navigation positioning ground main control station 3 can be a fixed hidden navigation positioning fixed station or a hidden navigation positioning vehicle-mounted static center communication station which can move along with a vehicle, the number of the hidden navigation positioning ground main control stations is more than 8, and hidden navigation positioning signals 2 are transmitted to a preselected hidden satellite constellation 1 by each hidden navigation positioning ground main control station and are transparently forwarded and received by an intelligent receiver 4 with an anti-interference digital multi-beam electric scanning antenna, so that the functions of telegraph demodulation, distance measurement, positioning calculation and the like are realized. The hidden navigation ground main control station generates an orbit determination signal, the orbit determination signal goes up to a hidden satellite constellation 1, the passive orbit determination receiver of the passive orbit determination station 5 receives the signal after the signal is forwarded by the hidden satellite constellation, the data is returned to the hidden navigation ground main control station, and the orbit determination of the satellite is completed by the orbit calculation center.
The hidden satellite navigation positioning system does not need to transmit a special navigation satellite. The covert satellite constellation consists of a universal GEO communication satellite and comprises three satellites, as shown in fig. 2. First, GEO geosynchronous geostationary orbit satellites; second, a sigso (suspended incorporated Geostationary orbit) satellite, which is a GEO satellite that is retired and reused. When only the position maintenance in the east-west direction is retained and the position maintenance in the north-south direction is abandoned, a small-inclination inclined orbit geostationary satellite, i.e., SIGSO satellite, whose inclination angle increases by 0.9 degrees on average per year, whose service life depends on the amount of the remaining orbit-adjusting fuel, e.g., the remaining year fuel, can be used for 10 years, can be formed. The price is only about one tenth of the original normal use price; third, the IGSO satellite is a geosynchronous orbit satellite with an inclination angle of about 60 °, and a large inclination angle generates a small geometric factor, which is the key to obtain high positioning accuracy. The constellation formed by the three earth orbit satellites has the core star of IGSO, and the DOP value determining the positioning precision is close to that of the GPS. One of the two characteristics of this "universal GEO communication satellite" is that it is distributed around the equatorial plane, and currently there are 363 worldwide, 348 including the C and Ku frequency bands, 273 available for covert navigation, besides the non-transparent transponder star and military star, plus 30 purchased retired stars SIGSO and 333 available for the special IGSO to be launched. While there are only about 30 GPS-enabled satellites per system. This shows that the hidden navigation can use more than 10 times of the satellite, and has strong anti-hit ability. When the hidden satellite navigation system is attacked or interfered, the advantages of more satellite resources can be utilized to implement anti-interference measures such as satellite changing (navigation satellite changing), frequency changing (navigation frequency point changing), code changing (navigation ranging code changing) and the like.
The hidden navigation positioning signal has the characteristics that: the signal power is very low. There is extensive interference from the space and ground on "pan GEO communication satellites". The international telecommunications union stipulates that interference below 2% of full scale is not blamed. The hidden satellite navigation positioning system utilizes the characteristic to 'borrow' (utilize without compensation) the normally used satellite and additionally transmit the additional weak signal with one percent, two percent or even four percent of power to transmit navigation information. I.e., a very low power, covert signal is added during normal communication signal broadcast, or a very low power, navigation signal is added by the ground station during transparent relay communication. In addition, the hidden navigation positioning signal adopts a pseudo noise ranging code with a higher rate, the rate of the ranging code is 20Mcps and above, the signal bandwidth is as high as 40MHz and above, and the power spectral density of the hidden satellite navigation signal is very low because the power of the hidden navigation signal is lower than that of a conventional signal by more than 20 dB. The navigation signal is hidden in the conventional service signal, even can be hidden in noise, the signal is hidden, so the transmitting position and the transmitting mode are hidden, the transmitting and forwarding frequency is hidden, the transmitting code is hidden, the transmitting and forwarding satellite is hidden, and the direction and the range of the satellite are also hidden. In the signal receiving part, the receiver and associated antenna system are also concealed. This concealment is a seven-dimensional concealment. The antenna polarization of the receiver is covert, as is the antenna form.
On a 'universal GEO communication satellite' which can be utilized without compensation, there is a conventional full-scale original service signal. This is also a strong disturbance for concealing the navigation signal. However, because the hidden satellite navigation signal adopts the broadband spread spectrum technology, the interference can be weakened by more than one thousand times by the uncorrelated characteristic of the navigation ranging code and the original service signal after entering the intelligent receiver for correlation demodulation. Therefore, the covert navigation signal is not affected by the original service signal. Therefore, the hidden navigation positioning system and the original service signal of the utilized 'generic GEO communication satellite' can realize mutual noninterference and can keep respective normal operation.
The hidden navigation positioning ground main control station mainly comprises an antenna system (including a servo control system), radio frequency equipment, a hidden navigation signal comprehensive baseband, system time frequency generation and distribution equipment and main control system equipment. The antenna system comprises a C/Ku dual-band feed network, the caliber of the antenna of the fixed station is more than 3.7 meters, and the caliber of the antenna of the vehicle-mounted static through station is about 2 meters. In order to realize the rapid switching of the directional satellite so as to realize the function of changing the satellite, the fixed station antenna adopts a turntable type seat frame; in order to realize high-precision tracking of the SIGSO satellite and the IGSO satellite, the antenna adopts a single-pulse tracking mode.
The radio frequency equipment is divided into C, Ku frequency bands, including a high-power amplifier, an up-converter, a down-converter and a low-noise amplifier of a C frequency band, a high-power amplifier, an up-converter, a down-converter and a low-noise amplifier of a Ku frequency band, etc. The radio frequency equipment can adjust the working frequency point under the instruction of the master control system so as to realize the frequency conversion function.
The hidden navigation signal comprehensive baseband edits and generates a navigation message, and the message is encrypted and corrected; meanwhile, the message is recovered, and the message to be sent and the message to be recovered are compared and verified; then, the generated navigation message is encoded, spread and modulated to generate various intermediate frequency signals, and the intermediate frequency signals are sent to a radio frequency channel to be subjected to up-conversion and amplification processing and then uplink to a corresponding satellite; and receiving a downlink navigation signal, amplifying the downlink navigation signal by a low-noise amplifier, carrying out frequency conversion by a down converter, and then sending the downlink navigation signal to a comprehensive baseband for data processing such as despreading, demodulation, pseudo-range and Doppler measurement, text analysis and the like.
The master control system equipment completes centralized monitoring control of the working state of the navigation ground master control station and stores system operation logs; completing unified management of navigation ground main control station data and network; finishing the interaction of external data of the navigation ground main control station; and completing system decision of satellite changing, frequency changing and code changing. The master control system has a data processing function and comprises navigation message data processing, measurement rail data processing and signal analysis processing. Each function respectively applies a corresponding data analysis algorithm, provides various navigation and time service information for the hidden navigation positioning ground main control station through data analysis and processing, and calculates to obtain data information such as satellite phase correction quantity, frequency correction quantity, clock error correction quantity, ephemeris correction quantity and the like; the master control system combines the received orbit determination data with satellite loop time delay, carrier frequency and Doppler frequency obtained by self measurement, as well as receiving channel time delay, frequency deviation measurement data and comprehensive baseband transmission frame mark pulse and system second pulse time difference data, and calculates virtual clock time parameters and frequency parameters and corresponding code frequency, code phase, carrier frequency and carrier phase adjustment quantity; and sending the measured orbit data, the virtual clock parameters, the differential correction data, the air pressure height measurement data, the frequency correction quantity and the like to the hidden navigation comprehensive baseband.
A hidden satellite constellation resource library is arranged in a master control system database of the hidden navigation positioning ground master control station. The resource library stores detailed information of the hidden satellite constellation, including satellite name, orbit position, whether there is an inclination angle, the size of the inclination angle, available transponder number, available frequency point, available transponder bandwidth, available navigation ranging code number, etc. The master control system can calculate the DOP value of the hidden satellite navigation geometric accuracy factor according to the range of the navigation service area, select the constellation combination which enables the DOP value to be as small as possible so as to achieve higher positioning accuracy, further select specific navigation frequency points and navigation ranging codes on the group of satellites, and broadcast the specific navigation frequency points and navigation ranging codes as system control instructions to various intelligent receivers. After each intelligent receiver receives the instruction, the antenna beam of the receiver can be pointed to the satellite to be used, the working frequency point of the radio frequency module is adjusted to the frequency point to be used, and the local navigation ranging code of the baseband processor is replaced by the ranging code to be used. Therefore, the strong anti-interference capability of changing stars, frequencies and codes is realized. Therefore, the hidden navigation positioning signal is a navigation communication integrated signal. Besides the navigation message, the signal structure of the hidden navigation positioning signal also has a 'system control command' message.
The passive orbit determination station provides high-precision and real-time satellite orbit position and orbit correction value for a hidden navigation positioning system consisting of a universal GEO communication satellite, and a user can select and use the orbit position and the orbit correction value as required. The method mainly comprises the following steps: the device comprises at least 4 measuring rail reference stations positioned on the surface of the earth and 1 data processing center, wherein the distance between the reference stations is as large as possible, and the reference stations are distributed in several directions in a positioning coverage range so as to obtain higher measuring rail precision. And 3 high-precision ranging receivers are distributed in each passive orbit determination reference station and respectively correspond to 3 satellites. The aperture of the passive measurement rail station antenna can be selected to be about 1.2 meters. Each antenna is provided with a servo tracking system so as to well track the SIGSO and IGSO satellites and realize the polling task of all covert satellite constellations. The clocks of these receivers are provided by a system time frequency generation and distribution device in the covert navigation positioning ground master control station. Establishing a data processing center at a hidden navigation positioning ground main control station, wherein main equipment is a high-performance data processing server to process satellite signals acquired by a reference station receiver, mainly comprises code phase and carrier phase data, calculates the position correction quantity of a measured satellite, and counts the orbit determination precision; the data processing center transmits the calculated satellite position correction quantity to a master control system in the hidden navigation master control station through the internet network, arranges the information into a navigation message, and injects the information into the satellite through the uplink station for the user to use when positioning.
The system time frequency generating and distributing equipment generates a time frequency reference signal with high stability and high reliability, provides a system time and frequency signal which is traced to national standard time UTC (NTSC) for the hidden navigation positioning ground main control station and the passive orbit determination station, and realizes the synchronous operation of equipment of each station in the system. The two atomic clocks are complementary to each other to form reliable time frequency signal generation. The clock group generates system time, remote high-precision comparison with national standard time is realized through a satellite, and the output of a main clock in the clock group is controlled according to a comparison result so as to keep synchronization with the standard time. The remote time comparison link is a key link for supporting each navigation positioning ground master control station to keep time synchronization, and according to the importance of the remote time comparison link, a set of comparison links is designed for the standby clock, so that the reliability of the comparison links is improved through redundancy configuration, and support data are provided for self-monitoring of the integrity of the system time to assist in judging whether the system time is normal or not.
The intelligent receiver has the software and hardware functions of receiving multi-dimension, multi-frequency and multi-signal channel and intelligently selecting and judging. The intelligent receiver adopts a mode of combining the generic GEO satellite navigation and the autonomous navigation (inertial navigation, geomagnetic navigation and barometric altitude measurement), and utilizes the autonomous navigation module to keep the continuity of navigation during switching, and meanwhile, the autonomous navigation module can improve the navigation sampling rate and realize the sampling requirement of characteristic equipment.
Typically, a navigation positioning receiver cannot demodulate a signal that is 100-200 times lower in power than conventional navigation. The intelligent hidden satellite navigation and positioning receiver adopts an anti-interference digital multi-beam electric scanning antenna, and has a gain of about 20dBi in a plurality of satellite directions used for positioning. Therefore, the receiver has enough signal-to-noise ratio to realize demodulation, pseudo range and telegraph text are obtained, and the intelligent receiver can realize positioning. Meanwhile, the bandwidth of the concealed navigation signal is more than 2 times of that of the GPS precise code, and the positioning precision of the system is improved.
In order to realize the receiving function of multi-satellite, multi-frequency and multi-signal, the intelligent receiver adopts a high-gain anti-interference digital multi-beam electric scanning antenna. Because the hidden navigation signal is very weak, the traditional omnidirectional antenna cannot be used, and a high-gain directional antenna must be designed. For satellite navigation, three-dimensional positioning needs to be achieved, at least signals of more than four satellites need to be received simultaneously, and in order to improve navigation positioning accuracy, the satellites need to be distributed in different directions, so that for an intelligent receiver antenna, multiple beams are needed to be self-adaptively aligned to each satellite. According to the system link budget, in order to enable the signal-to-noise ratio of the navigation signals from each satellite to reach the ground to be close, the power transmitted by the hidden navigation ground main control station can be intelligently adjusted according to the requirement. If the intelligent receiver is installed on a mobile carrier, the position and the direction of the antenna can change at any time, so that the antenna needs to have a real-time automatic satellite alignment function. When the system switches the concealed satellite, the anti-interference digital multi-beam electric scanning antenna can point the beam to the satellite to be used according to the system indication, and the 'satellite changing' function of concealed satellite navigation is realized.
The anti-interference digital multi-beam electric scanning antenna is a closed-loop feedback control system formed from antenna array and real-time self-adaptive signal receiving processor, and is characterized by that it uses feedback control method to automatically regulate directional diagram of antenna array, and makes the main beam be directed at satellite so as to make it form null or lower power directional diagram gain in the interference direction, and offset the interference signal, and can make the useful signal be strengthened so as to attain the goal of resisting interference. The specific technical indexes are as follows: receiving gain: about 20 dBi; frequency band: C/Ku band; the functions are as follows: according to the selected satellite constellation, the main beam direction of the receiving antenna is adjusted in a self-adaptive manner, and automatic satellite alignment is carried out; the antenna structure is as follows: a low profile, microstrip array patch antenna; the number of the paired stars is: at least more than 6 communication satellites are tracked simultaneously.
In the intelligent receiver, a hidden navigation positioning signal enters a radio frequency low noise amplifier through an antenna and an external band-pass radio frequency filter, enters a frequency mixer, reaches analog intermediate frequency after frequency conversion, is further amplified and filtered, and then is output through an analog or digital port and supplied to a baseband processor for processing. The baseband processor tracks and captures the received intermediate frequency digital signals, despreads and demodulates the intermediate frequency digital signals, and can switch the radio frequency and the ranging code according to requirements, thereby realizing frequency conversion and code conversion hidden satellite navigation positioning.
Example 1
By adopting the covert satellite navigation positioning system, the frequency band is C-band, the covert navigation positioning main control station is 5 (4 main and 1 standby) vehicle-mounted static central station, the caliber of each vehicle-mounted antenna is 1.8 m, and the configured power amplification power of the C-band is 25W. The power of the concealed navigation positioning signal occupying the satellite is one percent of the full load power. One static center-through vehicle-mounted station is provided with a high-precision atomic clock to generate navigation system time, and is provided with a high-precision time frequency system to enable the time of 5 navigation signals going to the stations to be synchronous and uniform. The satellite constellation selects 5 of C-band communication satellites within a visible range, of which there are 2 low dip tilt orbit satellites with a DOP value of 50. The antenna of the positioning receiver is an adaptive antenna with 5 beams, and the antenna gain is 19 dBi. The distance measurement precision of the system is 0.10 meter, and the positioning precision is 5 meters.
Example 2
By adopting the hidden satellite navigation positioning system, the frequency band is Ku wave band, the hidden navigation positioning main control station is 8 (7 main and 1 standby) fixed ground stations, the aperture of each antenna is 16 meters, and the configured power amplifier power of the Ku wave band is 20W. The covert navigation signal occupies one-two-hundredth of the full-load power of the satellite. The hidden navigation positioning master control station is internally provided with a high-precision atomic clock for generating navigation system time and is provided with a high-precision time frequency distribution system, so that the time of 8 navigation signal uplink stations is synchronized and unified. The satellite constellation selects 8 Ku-band communication satellites in a visual range, wherein 2 SIGSO small-dip angle inclined orbit satellites and 1 IGSO inclined orbit satellite have a DOP value of 10. The antenna of the positioning receiver is an adaptive antenna with 8 beams, and the antenna gain is 21 dBi. The distance measurement precision of the system is 0.10 meter, and the positioning precision is 1 meter.
Example 3
By adopting the hidden satellite navigation positioning system, the frequency band is C-band, the hidden navigation positioning main control station comprises 8 (7 main and 1 standby) fixed ground stations, the aperture of each antenna is 3.7 m, and the configured power amplifier power of the C-band is 200W. The covert navigation signal occupies one fourth hundredth of the full load power of the satellite. The hidden navigation positioning master control station is internally provided with a high-precision atomic clock for generating navigation system time and is provided with a high-precision time frequency system, so that the time of 8 navigation signal uplink stations is synchronized and unified. The satellite constellation selects 8C-band communication satellites within a visual range, wherein 1 SIGSO small-dip angle inclined orbit satellite and 1 IGSO inclined orbit satellite have a DOP value of 20. The antenna of the positioning receiver is an adaptive antenna with 8 beams, and the antenna gain is 25 dBi. The distance measurement precision of the system is 0.10 meter, and the positioning precision is 2 meters.
According to the embodiment, the hidden satellite navigation system adopts the generic GEO communication satellite as a navigation constellation, and can still realize high-precision positioning under the condition that the power of a hidden navigation signal is only one percent or less than the full load power of the satellite, and the positioning precision can reach the meter level, so that accurate hidden navigation can be realized.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. A hidden satellite navigation positioning system is characterized by comprising a hidden satellite constellation (1), a hidden navigation positioning signal (2), a hidden navigation positioning ground main control station (3), an intelligent receiver (4) and a passive orbit determination station (5);
the hidden satellite constellation (1) is a universal GEO communication satellite constellation, and consists of a C/Ku frequency band GEO commercial communication satellite, an SIGSO small-inclination angle synchronous orbit satellite and an IGSO inclined orbit satellite, the working mode is that IGSO satellite navigation signal direct emission and GEO and SIGSO satellite forwarding are combined, and the hidden navigation signal is sent to a user receiver, so that the functions of positioning, time service, speed measurement and the like of the user receiver are realized;
the hidden navigation positioning signal (2) is hidden under the original service signal of the generic GEO communication satellite, the signal power is less than one percent of the full load power of a satellite transponder, the bandwidth of the navigation signal is more than 40MHz, and the reduction amplitude of the signal-to-noise ratio of the original signal is not more than 0.3 dB;
the hidden navigation positioning ground main control station (3) is a fixed hidden navigation positioning fixed station or a hidden navigation positioning vehicle-mounted static through station capable of moving along with a vehicle, and comprises an antenna system (6), a radio frequency device (7), a hidden navigation signal comprehensive baseband (8), a system time frequency generating and distributing device (9) and a master control system (10) for completing the generation, transmission, reception, processing, monitoring and evaluation of hidden navigation signals of satellites in corresponding frequency bands, and performing satellite-ground time synchronization and information annotation on the satellites;
the intelligent receiver (4) comprises an antenna module (11), a radio frequency module (12), a baseband processor module (13) and an autonomous navigation module (14), wherein the antenna module (11) receives a navigation signal from a covert satellite constellation (1), the radio frequency module (12) receives the covert navigation signal from the antenna module (11), the covert navigation signal is amplified by a low noise amplifier and subjected to frequency conversion by a down converter and then is sent to the baseband processor module (13), the autonomous navigation module (14) receives the signal from the baseband processor module (13), and when the system needs to switch a navigation mode, the autonomous navigation module (14) is started to realize uninterrupted navigation;
the passive orbit determination station (5) comprises at least four orbit determination reference stations positioned on the earth surface, a receiver of the orbit determination reference station collects satellite signals, calculates the position correction quantity of the measured satellite, counts the orbit determination precision, arranges the satellite position correction quantity information into navigation messages, and injects the satellite into the ground main control station (3) through hidden navigation positioning for the user to use during positioning.
2. The covert satellite navigation and positioning system of claim 1, wherein said covert navigation and positioning ground master control station (3) is a set of covert navigation and positioning fixed stations, the number of which is about 8, and the aperture of the antenna is more than 3.7 meters.
3. The covert satellite navigation and positioning system of claim 1, wherein said covert navigation and positioning ground master control station (3) is a mobile vehicle-mounted stationary central station, which is loaded on a mobile vehicle, the number of said stations is about 8, and the aperture of said antenna is about 2 meters.
4. Covert satellite navigational positioning system according to claim 1, wherein the antenna module (11) of the smart receiver (4) employs an interference-immune digital multi-beam electronically swept antenna having more than 6 steerable beams, each beam having a maximum gain of 20 dBi.
5. The covert satellite navigation and positioning system of claim 1, wherein each orbit determination reference station has three high accuracy ranging receivers, one for each satellite.
6. Covert satellite navigational positioning system as claimed in claim 1, wherein said covert navigational positioning signal (2) has a power of one two hundredth of the full load power of a satellite transponder.
7. Covert satellite navigational positioning system as claimed in claim 6, wherein said covert navigational positioning signal (2) has a power of one fourth percent of the full load power of a satellite transponder.
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| CN111308511A (en) * | 2020-03-05 | 2020-06-19 | 中国科学院微小卫星创新研究院 | Autonomous health management system and method for navigation satellite load subsystem |
| CN112698373A (en) * | 2020-12-10 | 2021-04-23 | 中国科学院国家授时中心 | Device and method for realizing precise distance measurement of navigation signals generated on ground |
| CN112946705A (en) * | 2021-02-01 | 2021-06-11 | 中国人民解放军63923部队 | System and method for positioning forwarding interference of satellite transponder |
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| CN113489587A (en) * | 2021-07-30 | 2021-10-08 | 南京信息工程大学 | Covert communication method, system, storage medium and computing device |
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| CN111308511A (en) * | 2020-03-05 | 2020-06-19 | 中国科学院微小卫星创新研究院 | Autonomous health management system and method for navigation satellite load subsystem |
| CN112698373A (en) * | 2020-12-10 | 2021-04-23 | 中国科学院国家授时中心 | Device and method for realizing precise distance measurement of navigation signals generated on ground |
| CN112946705A (en) * | 2021-02-01 | 2021-06-11 | 中国人民解放军63923部队 | System and method for positioning forwarding interference of satellite transponder |
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| CN113009528B (en) * | 2021-02-07 | 2023-07-25 | 成都市精准时空科技有限公司 | Multi-frequency multi-mode satellite positioning communication device and hybrid positioning information control method |
| CN113489587A (en) * | 2021-07-30 | 2021-10-08 | 南京信息工程大学 | Covert communication method, system, storage medium and computing device |
| CN113489587B (en) * | 2021-07-30 | 2023-05-16 | 南京信息工程大学 | Covert communication method, covert communication system, storage medium and computing device |
| CN115079237A (en) * | 2022-08-16 | 2022-09-20 | 长沙金维信息技术有限公司 | RTK positioning method and navigation method based on frequency point selection |
| CN115079237B (en) * | 2022-08-16 | 2023-01-06 | 长沙金维信息技术有限公司 | RTK positioning method and navigation method based on frequency point selection |
| CN116609807A (en) * | 2023-07-10 | 2023-08-18 | 中国科学院国家天文台 | Method for calculating pseudo-range measurement error of hidden satellite navigation system |
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