CN111596541A - Autonomous controllable multimode anti-interference time system equipment - Google Patents
Autonomous controllable multimode anti-interference time system equipment Download PDFInfo
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- G—PHYSICS
- G04—HOROLOGY
- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
- G04R20/02—Setting the time according to the time information carried or implied by the radio signal the radio signal being sent by a satellite, e.g. GPS
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- G—PHYSICS
- G04—HOROLOGY
- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
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- G—PHYSICS
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- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
- G04R20/02—Setting the time according to the time information carried or implied by the radio signal the radio signal being sent by a satellite, e.g. GPS
- G04R20/04—Tuning or receiving; Circuits therefor
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- G—PHYSICS
- G04—HOROLOGY
- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
- G04R20/08—Setting the time according to the time information carried or implied by the radio signal the radio signal being broadcast from a long-wave call sign, e.g. DCF77, JJY40, JJY60, MSF60 or WWVB
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- G—PHYSICS
- G04—HOROLOGY
- G04R—RADIO-CONTROLLED TIME-PIECES
- G04R20/00—Setting the time according to the time information carried or implied by the radio signal
- G04R20/08—Setting the time according to the time information carried or implied by the radio signal the radio signal being broadcast from a long-wave call sign, e.g. DCF77, JJY40, JJY60, MSF60 or WWVB
- G04R20/10—Tuning or receiving; Circuits therefor
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Abstract
The invention belongs to the technical field of time system equipment, and discloses autonomous controllable multimode anti-interference time system equipment, which comprises a time-frequency signal receiver module, a multimode information fusion module, a time and frequency processing module, a time signal interface protocol module, an interface conversion module, a frequency control module, a man-machine interaction module, a self-checking module and a power supply module, wherein the time-frequency signal receiver module is connected with the time-frequency signal receiver module; the multimode information fusion module comprises a UTC processing submodule, a short wave 1PPS processing submodule, a long wave 1PPS processing submodule and a 1PPS timekeeping submodule, and the 1PPS submodule is synthesized; the anti-deception jamming processing unit comprises a power consistency detection subunit, a power normality detection subunit, a positioning mode switching detection subunit, a pseudo-range change rate detection subunit, an inertial navigation joint detection subunit, a least square redundancy detection subunit and a deception jamming judgment subunit. The invention improves the accuracy of output frequency, and also improves the time keeping precision when three time service modes are unavailable and the precision of internal signal processing.
Description
Technical Field
The invention belongs to the technical field of time system equipment, and particularly relates to autonomous controllable multimode anti-interference time system equipment.
Background
The time frequency plays an important role in national economy, national defense construction and basic scientific research as an important basic physical quantity. A time unification device (simply referred to as a time unification device) is a device that provides a unified standard time signal and a standard frequency signal. The time reference becomes important basic information of the whole national information construction, and the high-precision time service has wide application requirements in the fields of communication, networks, financial securities, radio and television, electric power, national defense, aerospace, basic research and the like. The frequency signal is a necessary signal of all communication, network and electronic equipment; the accuracy and stability of frequency signals play a crucial role in the performance of the systems and equipment (the current development situation and the development prospect analysis of the Chinese time-frequency industry in 2018; the Chinese industry information network (http:// www.chyxx.com/industry/201801/604269.html), and 16.01.16.2018). 7/14 in 2019, the technical failure of the European Galileo satellite navigation positioning system causes the interruption of partial navigation service, namely, the system time system of the system fails, and the whole system is crashed.
The current main time service method mainly comprises a plurality of modes such as short-wave time service, long-wave time service, satellite-based time service mode, network time service and the like. The satellite-based time service mode of the satellite navigation positioning system is adopted, such as Beidou, GPS and Glonass, the time service precision is high and can reach 50ns, the time service response time is short and is generally less than 2 minutes, but the time service is easy to be shielded, interfered and deceived (Zhang politics, Hezhenhua, Zhengpengyu; network time synchronization system construction research based on the Beidou system; the ninth annual meeting of China satellite navigation academic corpus; 2018-05-23; Harbin.). Short wave time service is cheap and convenient, the annual blocking rate is low, generally less than 0.13 per thousand, and the precision is only about +/-lms. The long-wave time service coverage capacity is stronger than that of short waves, the time service precision reaches microsecond level, but only 8 hours of time service are transmitted every day, and the annual blocking rate is higher. The network time service is based on the time service mode of the Internet or the local area network, the time service precision of the local area network can reach 1ms, the precision of the Internet can reach 10ms, the network time service is characterized by being compatible with an Internet protocol, and other auxiliary equipment is not needed for a terminal. At the present stage, most of time management equipment in the market is based on a satellite-based time service mode, and most of time sources for network time service are based on the satellite-based time service mode. However, the continuity, availability and anti-interference of the satellite navigation positioning system still appear to be weak for some important occasions, which is specifically shown in the following: signals of a satellite navigation positioning system are easy to be shielded, an antenna needs to be placed outdoors in a wide area to receive the signals of the satellite, and the satellite navigation positioning system is difficult to be applied indoors; the signal openness of a satellite navigation positioning system enables the satellite navigation positioning system to be easily interfered and deceived by the outside, now, navigation war becomes a hot spot direction of electronic war, and the interference and the deceived become easier and easier; the localization degree is low; although the Beidou I, II and III navigation positioning systems in China are mature, most of the chips of the receivers are foreign chips, the degree of domestic autonomy is low, and certain hidden dangers exist. The characteristics of the four time service modes can be seen that each mode has advantages and disadvantages, if the four time service modes can be fully fused, the disadvantages are complemented and overcome, the advantages are mutually played, and the performance and the reliability of the time management equipment can be multiplied. The multi-mode combination mode time system equipment can improve the robustness and reliability of the system while improving the performance of the system.
At present, the main frequency source comprises a quartz crystal oscillator and an atomic clock, and the quartz crystal oscillator is a module containing a quartz crystal and an oscillation circuit and can directly generate oscillation signals to be output. Mainly comprises the following types:
XO, general type (Crystal oscillator);
TCXO Temperature compensated crystal oscillator (Temperature compensated crystal oscillator);
OCXO constant temperature crystal oscillator (Oven-controlled crystal oscillator); the constant temperature crystal oscillator is divided into a single-tank constant temperature crystal oscillator and a double-tank constant temperature crystal oscillator;
VCXO, Voltage-controlled crystal oscillator (Voltage-controlled Crystal oscillator); the voltage-controlled oscillator can adjust the output frequency by controlling the voltage, and the XO, TCXO and OCXO generally have a voltage control function.
The atomic clock is a common name of a frequency measurement standard device for locking the frequency of an external oscillator by using the radiation frequency of energy level transition of atoms or molecules, and is commonly called as a quantum frequency standard or an atomic frequency standard. The material mainly comprises rubidium atomic clock, cesium atomic clock, hydrogen atomic clock and the like according to different materials. The atomic clock has the characteristics of high accuracy and good stability, but the technical difficulty and the cost are also high. At present, the current situation of domestic frequency sources mainly comprises:
the temperature compensated crystal oscillator TCXO is close to the level of international like products;
the performance of the constant temperature crystal oscillator OCXO is difficult to reach the international advanced level, and the volume is larger than that of the constant temperature crystal oscillator OCXO at abroad;
rubidium atomic clock and cesium atomic clock have weak localization capability, large performance index and volume difference and price more than one time higher than that of foreign countries.
From the current situation of time service and frequency source, many domestic time management devices can meet the basic application requirements at the present stage; however, the devices depend on a satellite navigation positioning system excessively, the anti-interference capability is weak, and the localization degree is low; the time-frequency device is difficult to meet the application requirements in complex environments such as high-confrontation period, wartime and the like, and particularly, the time-frequency device is weak at present for some key systems and nodes which are related to information security of national civilization and defense.
At home and abroad have more basesProvided are a time service module and a system of a satellite navigation positioning system. The performance of the time-line equipment developed in China is basically equivalent to that of the foreign equipment. For example, the U-blox-based LEA-M8T design and realization of a rapid high-precision time service system by Changchun optical precision machinery and physical research institute of Chinese academy of sciences, and the time service precision can reach 30ns under the condition of normally receiving satellite signals. The time signal can be output under the condition that only one satellite is seen in severe weather, and the precision of the actually measured synchronous signal is 600 ns. With the development of the Beidou system, some units and companies in China begin to research and develop time service equipment based on the GPS and the Beidou system, for example, a time service positioning device is researched and designed by the second research institute 706 of the Chinese space science and technology group, the time service positioning device not only has various functional characteristics of the Beidou and GPS satellite navigation system mobile terminal, but also combines auxiliary time service functions such as B code and external timing, and in addition, the high-precision self-time-keeping function is realized, and the time-keeping precision is about 24 hours and 1ms of error. A series of Beidou second generation/GPS time service modules and board cards are developed by Chengdu Tianao electronic corporation, a time-frequency signal performance tester is also developed, and the company can independently design and manufacture a rubidium atomic clock and achieves the international advanced level in the aspect of basic performance. The Simian synchronous electronic technology limited company develops complete Beidou second generation/GPS time service system boards and devices, and the time service precision of the rubidium atomic clock based clock synchronization device can reach 10 ns. HJ5435-BD GPS synchronous clock developed by Beijing Taiford electronic technology Limited, the output frequency stability of which is 5 x 10-12S; the error of 1PPS (one pulse per second) in case of normal reception is less than 30 ns.
The main features of these existing devices are as follows:
(1) the time service based on the satellite navigation positioning system is mainly, no backup is provided on the time service source, when the satellite navigation positioning system is unavailable, a frequency source timekeeping method is mostly adopted, and the accumulated error is larger and larger.
(2) The anti-interference capability is poor, and basically, the anti-jamming capability and the anti-deceptive interference capability are not provided.
(3) The localization degree is low, although the performance of the whole machine can reach the performance of similar foreign products, the main processors, frequency sources and the like are foreign chips and devices, the autonomy degree is not high, and certain hidden dangers and risks exist.
(4) In signal processing, when various satellite navigation positioning systems are adopted for time service, only 1PPS in various modes is optimized and supplemented, real data fusion processing is not carried out, and the performance of the whole system is not obviously improved. The control precision of the frequency is not enough, and the highest clock rate of a processor can be achieved generally, and most of devices adopt ARM processors; therefore, the time and frequency accuracy is not high, and the time keeping accuracy is also not high.
Information security is a problem which must be paid great attention to by any country, government, department and industry, and is a national security strategy which cannot be ignored. For time-series equipment, the safety of the time-series equipment directly influences the information safety and the system safety of the application field of the time-series equipment, and if the time-series equipment has problems, a control system of a power grid and a certificate system crash; banking systems, internet systems, and military command systems are all greatly affected. Therefore, the improvement of the anti-interference capability of the time system equipment has important significance on the information security of many systems.
In summary, the multi-mode time system technology based on the satellite navigation positioning system, the long wave, short wave and other time service technologies, the suppression and deception interference resisting technology of the time system equipment, the autonomous controllable technology and the like are broken through; the research and realization of the time-domain equipment with high localization degree, strong robustness and strong anti-interference capability have important practical significance.
Disclosure of Invention
The invention provides an autonomous controllable multimode anti-interference time system device, aiming at a series of problems of overhigh dependence degree, weaker anti-interference capability, low autonomous controllable degree and the like of the conventional time system device on a satellite navigation positioning system.
In order to achieve the purpose, the invention adopts the following technical scheme:
an autonomous controllable multimode anti-interference time system device comprises a time-frequency signal receiver module, a multimode information fusion module, a time and frequency processing module, a time signal interface protocol module, an interface conversion module, a frequency control module, a man-machine interaction module, a self-checking module and a power supply module;
the time-frequency signal receiver module is used for receiving the time information of the short wave, the long wave and the navigation satellite, wherein the time information comprises 1PPS, UTC and state information, and inputting the time information into the multimode information fusion module;
the multimode information fusion module is used for fusing the time information, and comprises UTC time signal comparison and 1PPS time signal fusion and optimization;
the time and frequency processing module is used for correcting the frequency by using the optimized 1 PPS;
the time signal interface protocol module is used for converting UTC and 1PPS time signal interface protocols according to requirements;
the interface conversion module is used for realizing level conversion and network interface functions;
the frequency control module is used for controlling the frequency information output by the time and frequency processing module;
the human-computer interaction module comprises a display control module and a touch screen and is used for human-computer interaction;
the self-checking module is used for realizing detection of each module and formation of error codes in the starting and working processes, and the detection result is displayed through the display control module;
the power module is used for converting an input 220VAC signal into a 24VDC signal for the whole device to use.
Furthermore, the time-frequency signal receiver module comprises a short wave receiver submodule, a long wave receiver submodule and a time service type receiver submodule, the short wave receiver submodule comprises a short wave receiver, the long wave receiver submodule comprises a long wave receiver, the time service type receiver submodule comprises a time service type receiver, an anti-interference antenna and an anti-cheating interference processing unit, and the anti-cheating interference processing unit is used for detecting cheating interference through post-processing of output information of the time service type receiver and outputting alarm information to the outside.
Furthermore, the multimode information fusion module comprises a UTC processing submodule, a short wave 1PPS processing submodule, a long wave 1PPS processing submodule and a 1PPS timekeeping submodule, and the 1PPS submodule is synthesized;
the UTC processing submodule is used for checking and comparing the universal coordination time obtained by the three receivers, selecting correct UTC and outputting the state whether the UTC time of the three receivers is consistent to the outside;
the short wave 1PPS processing submodule is used for correcting the error of the 1PPS of the short wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the short wave receiver through smooth filtering, outputting 1PPS of the short wave receiver after correcting the error, and giving a confidence coefficient parameter of the short wave receiver according to the stability of the error for a subsequent 1PPS synthesis submodule to use;
the long wave 1PPS processing submodule is used for correcting the error of the 1PPS of the long wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the long wave receiver through smooth filtering, outputting 1PPS of the long wave receiver after correcting the error, and providing a confidence coefficient parameter of the long wave receiver for a subsequent synthesis 1PPS sub-module according to the stability of the error;
the 1PPS time keeping submodule is used for keeping time for the 1PPS acquired by the time service type receiver, and when the time service type receiver is invalid, counting and keeping the time service type receiver by adopting a disciplined accurate clock;
the synthesis 1PPS submodule is used for selecting 1PPS input by three receivers, the first selection is 1PPS output by a time service type receiver, the second selection and the third selection are respectively to select 1PPS output by a long wave receiver after error correction and 1PPS output by a short wave receiver after error correction according to confidence coefficient parameters of the long wave receiver and the short wave receiver, and the fourth selection is 1PPS output by a 1PPS time keeping submodule; the synthesize 1PPS sub-module is also used to smooth filter the selected 1PPS with the exact clock that has been disciplined.
Further, the frequency control module comprises a high-precision DA, a crystal oscillator/atomic clock, an amplifier and a power divider, and the high-precision DA, the crystal oscillator/atomic clock, the amplifier and the power divider are connected in sequence.
Furthermore, the anti-spoofing interference processing unit comprises a power consistency detection subunit, a power normality detection subunit, a positioning mode switching detection subunit, a pseudo-range change rate detection subunit, an inertial navigation joint detection subunit, a least square redundancy detection subunit and a spoofing interference judgment subunit.
Furthermore, the time and frequency processing module comprises a multi-phase-locked loop sub-module, a multi-phase counter and a loop filter.
Further, the time and frequency processing module and the frequency control module specifically perform processing of the frequency signal as follows:
a. amplifying a frequency signal output by a crystal oscillator/atomic clock by using a low-noise amplifier, and shunting the frequency signal by using a power divider, wherein one path is supplied to a multi-phase-locked loop submodule, and the other paths are output to the outside;
b. the frequency signal input to the multi-phase-locked loop submodule is subjected to frequency multiplication, and the multi-phase-locked loop submodule simultaneously outputs a plurality of clock signals with different phases;
c. inputting a plurality of clock signals with different phases into a multi-phase counter, and counting the externally input original 1PPS respectively;
d. averaging the counting values of different phase frequencies to obtain a counting average value;
e. calculating the error of the counting value through the counting average value and the ideal counting value;
f. the error value of the count value is averaged for a long time through a loop filter to obtain the correction quantity of the frequency parameter;
g. converting the correction quantity of the frequency parameter into a DA control quantity;
h. outputting the DA control quantity to a high-precision DA;
i. the high-precision DA generates an analog voltage control signal, controls the frequency of the crystal oscillator/atomic clock, and changes the output frequency until the error of the count value approaches 0.
Compared with the prior art, the invention has the following beneficial effects:
(1) time service technology based on integration of satellite navigation positioning system and three time service modes of long wave and short wave
The reliability and the stability of the whole equipment can be improved by the three time service modes. In the design process, the short-wave time service and the long-wave time service are corrected by using the satellite navigation time service with the highest precision instead of simple three-mode selection, so that error parameters of the two time service modes with the poor precision are obtained, and the confidence coefficients of the two time service modes are given according to the stability of errors. The best second selection can be selected when satellite navigation time service is unavailable. Meanwhile, high-speed and high-precision frequency signal processing is carried out, the accuracy of output frequency is improved, and the time keeping precision and the internal signal processing precision when three time service modes are unavailable are also improved.
(2) Integrated anti-interference technology based on antenna, signal processing and data post-processing
The time-domain equipment takes the anti-interference technology as a key point, and systematically designs an anti-interference scheme. The method adopts the array antenna technology to form the beam zero point from the airspace to resist the strong suppression interference, and selects the time service type receiver submodule capable of inhibiting the narrow-band interference from the frequency domain in the selection of the time service type navigation module. For the deception jamming which is most sensitive to the satellite navigation positioning system, the deception jamming detection is carried out by adopting six modes of power consistency detection, power normality detection, positioning mode switching detection, pseudo-range change rate detection, inertial navigation joint detection, least square redundancy detection and the like so as to prevent the whole system from being deceased due to deception of the first selected satellite navigation time service.
Drawings
Fig. 1 is a schematic diagram of an architecture of an autonomous controllable multimode anti-interference time system device according to an embodiment of the present invention;
fig. 2 is a schematic view of a multimode information fusion structure of an autonomous controllable multimode anti-interference time system device according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a spoofing interference resistant processing unit of an autonomous controllable multimode interference resistant time system device according to an embodiment of the present invention;
FIG. 4 is a graph of satellite power received by a receiver with spoofed interference generated by software radio in accordance with an embodiment of the present invention;
fig. 5 is a schematic diagram of a frequency signal processing flow of an autonomous controllable multimode anti-interference time system device according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a hardware architecture of an autonomous controllable multimode anti-interference time system device according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in fig. 1, an autonomous controllable multimode interference-resistant time system device includes:
an autonomous controllable multimode anti-interference time system device comprises a time-frequency signal receiver module, a multimode information fusion module, a time and frequency processing module, a time signal interface protocol module, an interface conversion module, a frequency control module, a man-machine interaction module, a self-checking module and a power supply module;
the time-frequency signal receiver module is used for receiving time information (including 1PPS, UTC and state information, wherein the state information mainly includes whether the time is effective or not, signal quality (signal-to-noise ratio and the like)) of the short wave, the long wave and the navigation satellite and inputting the time information into the multimode information fusion module;
the multimode information fusion module is used for fusing the time information, and comprises the comparison of UTC (universal coordinated time) time signals and the fusion and optimization of 1PPS (pulse per second) time signals;
the time and frequency processing module is mainly used for correcting the frequency by utilizing an optimized time signal 1PPS, and adopts a multi-phase-locked loop technology and is combined with a high-speed FPGA processor. By utilizing the characteristic of good long-stability characteristic of 1PPS, the frequency of 10MHz output by a crystal oscillator or an atomic clock is acclimatized by the 1PPS, a control signal of the crystal oscillator/the atomic clock is output, the frequency of the crystal oscillator/the atomic clock is corrected by the control signal, and the frequency of the crystal oscillator/the atomic clock is corrected in a closed loop for many timesHas an accuracy error of better than 10-11Magnitude above;
the time signal interface protocol module is used for converting UTC and 1PPS time signal interface protocols according to requirements, and comprises the steps of converting UTC time signals into a UART serial format and converting 1PPS and UTC into a format of a commonly used Irig-B DC code, so that the time signal interface protocol module is convenient for a user to use;
the interface conversion module comprises a level conversion function and a network interface function, and the level conversion can generate different level signals such as TTL level, RS232 level, RS422 differential level and the like according to the needs of a user; the network interface function is mainly to generate a network time service protocol signal NTP network time service signal according to given 1PPS and UTC time information; specifically, the level conversion function of the interface conversion module is realized by an RS422 differential chip; as an implementation mode, the RS422 differential chip is a CBM3485AS chip which is independently developed by Bai microelectronics (Beijing) Co., Ltd;
the frequency control module is used for controlling the frequency information output by the time and frequency processing module;
the human-computer interaction module comprises a display control module and a touch screen and is used for human-computer interaction; the method mainly comprises the steps of outputting parameters such as the state of the whole machine, time information, position information, time service source information and the like; a user can input control parameters through the touch screen to control the parameters of the whole machine;
the self-checking module is used for realizing detection of each module and formation of error codes in the starting and working processes, and the detection result is displayed through the display control module;
the power supply module is used for converting an input 220VAC signal into a 24VDC signal for the whole equipment to use; as an implementable mode, in order to ensure the stability and reliability of the power supply of the whole machine, a high-power precise linear power supply 4 NIC-X7224V 3A power supply of aerospace Long-Peak Chaoyang Power Limited is adopted, the power supply has good efficiency and ripple characteristics while ensuring the output power, and the implementable mode has the main characteristics of low noise, low ripple and high control reliability of an integrated chip; the low voltage difference circuit has small design power consumption and large design allowance; other voltages in the equipment adopt linear power supply modules, so that the output power is ensured, and meanwhile, the power supply module has good efficiency and ripple wave characteristics, adopts 24VDC (direct current) input from the outside as input, and respectively generates 12V, 9V, 5V, 3.3V and 1.2V direct current power supplies for all modules of the whole equipment;
specifically, the time-frequency signal receiver module comprises a short wave receiver submodule (short wave time service), a long wave receiver submodule (long wave time service) and a (Beidou, GPS and Glonass) time service type receiver submodule (satellite navigation (positioning system) time service), the short wave receiver submodule comprises a short wave receiver and a corresponding antenna, the long wave receiver submodule comprises a long wave receiver and a corresponding antenna, the time service type receiver submodule comprises a time service type receiver, an anti-interference antenna, an anti-cheating interference processing unit and an inertial navigation module, and the anti-cheating interference processing unit is used for detecting cheating interference through post-processing of output information of the time service type receiver and outputting alarm information to the outside. The time service type navigation receiver has the main functions of receiving satellite navigation signals of multiple systems and realizing time service and positioning; at the present stage, a plurality of localization modules capable of realizing the functions are provided, and anti-interference design is required; therefore, the type selection and design are mainly performed from the anti-interference perspective. As an implementation mode, the anti-interference antenna selects an US7760 antenna of Beijing and Chixingtong science and technology Limited company as an antenna of the time service type navigation receiver; selecting a full-system GNSS high-precision board UB4B0 developed by Beijing and Xinxingtong technology Limited company based on a new generation of Nebulis-II high-performance SoC chip as a time service receiver; the long-wave time service receiver adopts a Wessey radio wall clock movement independently developed by Xian Gao Huake technology Limited; the short wave receiver selects an SSD033A short wave CPCI board card type receiver of the same-party electronic technology limited company (national 713 th factory) to perform customized transformation, and the main parameters are as follows: the working frequency range is as follows: 0.1 MHz-30 MHz; frequency resolution: 1 Hz; demodulation method: USB, LSB, ISB, CW, AM, FM.
Specifically, the multimode information fusion module comprises a UTC processing submodule, a short wave 1PPS processing submodule, a long wave 1PPS processing submodule and a 1PPS timekeeping submodule, and the 1PPS submodule is synthesized; as shown in fig. 2.
The UTC processing submodule is used for checking and comparing the universal coordination time obtained by the three receivers, selecting correct UTC to prevent the time of error of one of the three receivers, and outputting the state whether the UTC time of the three receivers is consistent to the outside;
due to the influence of factors such as ionosphere disturbance, the precision of 1PPS obtained by short-wave time service is only millisecond level, and the precision of 1PPS obtained by a time service type receiver can reach 50 ns. The short wave 1PPS processing submodule is used for correcting the error of the 1PPS of the short wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the short wave receiver through smooth filtering, outputting 1PPS of the short wave receiver after correcting the error, and giving a confidence coefficient parameter of the short wave receiver according to the stability of the error for a subsequent 1PPS synthesis submodule to use;
the long wave 1PPS processing submodule is used for correcting the error of the 1PPS of the long wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the long wave receiver through smooth filtering, outputting 1PPS of the long wave receiver after correcting the error, and providing a confidence coefficient parameter of the long wave receiver for a subsequent synthesis 1PPS sub-module according to the stability of the error;
the 1PPS timekeeping submodule is used for timekeeping the 1PPS acquired by the time service type receiver, and when the time service type receiver is invalid, the 1PPS timekeeping submodule is used for counting and keeping the time service by adopting a disciplined accurate clock, so that the basic accuracy of outputting the 1PPS can be ensured in a short time even if the satellite navigation positioning receiver cannot position the time service, for example, if a rubidium atomic clock is used for timekeeping, the error of one hour is less than 300ns, but the accumulated error of timekeeping is larger and larger;
the synthesis 1PPS submodule is used for selecting 1PPS input by three receivers, the first selection is 1PPS output by a time service type receiver, the second selection and the third selection are respectively to select 1PPS output by a long wave receiver after error correction and 1PPS output by a short wave receiver after error correction according to confidence coefficient parameters of the long wave receiver and the short wave receiver, and the fourth selection is 1PPS output by a 1PPS time keeping submodule; the synthesize 1PPS sub-module is also used to smooth filter the selected 1PPS with the exact clock that has been disciplined to reduce the random jitter of the original 1 PPS.
Specifically, the frequency control module comprises a high-precision DA, a crystal oscillator/atomic clock, an amplifier and a power divider, frequency control words output by the time and frequency processing module are input into the high-precision DA, the DA converts the control words into analog voltage, the voltage controls the output frequency of the crystal oscillator/atomic clock, the output 10MHz frequency is amplified by the low-noise amplifier and then input into the power divider, the power divider outputs frequency signals in multiple paths, one path of the frequency signals is input into the time and frequency processing module to form a frequency adjustment closed loop, and the other paths of the frequency signals are output to the outside for users; as an implementation mode, an XHTF1011 rubidium atomic clock independently developed by Youtian Olympic electronic corporation is selected, an HG511F low-noise amplifier independently developed by Youhua Rui microelectronic corporation is selected as an amplifier to amplify the power of the frequency, and an LPD8S-DC-3 power divider independently developed by Suzhou Laier microwave technology Limited is selected as a power divider.
Specifically, the anti-spoofing interference processing unit comprises a power consistency detection subunit, a power normality detection subunit, a positioning mode switching detection subunit, a pseudo-range change rate detection subunit, an inertial navigation joint detection subunit, a least square redundancy detection subunit and a spoofing interference judgment subunit; as shown in fig. 3.
The input information of the anti-spoofing interference processing unit includes the following:
basic information of NMEA-0183 protocol; the information is output through a serial port and mainly comprises basic information such as position information, time information, satellite information and the like;
navigation message information; generally outputting the navigation message demodulated by the received satellite through an SPI (serial peripheral interface);
positioning observed quantity information; generally outputting through an SPI (Serial peripheral interface), wherein pseudo-range observed quantity and carrier observed quantity information are mainly output;
nine-axis information output by the inertial navigation module; and outputting through a serial port, wherein the direction information in three directions, the speed information of three axes and the attitude information of three dimensions are mainly used.
Specifically, the function of the anti-spoofing interference processing unit is realized in an embedded processor orange pie, and the functions of each subunit are as follows:
(1) power consistency detection subunit
The power of the normally received signals of each in-orbit satellite is greatly different, and the deception jamming signals are amplified by the same power amplifier, are transmitted by the same antenna and reach the same distance to the user; therefore, if a very detailed power control process is not performed on a spoofing interference source (each satellite performs power control independently, the cost is greatly increased), the power of each satellite received by the receiver is greatly consistent, as shown in fig. 4, when the spoofing interference generated by a software radio manner interferes with the receiver, the power of the satellite signal received by the receiver is highly consistent as shown in fig. 4, which shows that the signal power of the GPS satellite and the beidou satellite are highly consistent. Therefore, when the power consistency of the received satellite is too high, the power consistency can be used as a criterion for deceptive jamming.
(2) Power normality detection subunit
Through the satellite position and the local approximate position in the navigation message information, the maximum carrier-to-noise ratio of the satellite signal reaching the receiver can be calculated initially according to the satellite signal transmitting power and the free space attenuation. If the maximum carrier-to-noise ratio is exceeded to a certain extent, it can be used as criterion for deceptive interference. As shown in fig. 4, it is not possible for the power of the signal of each satellite to be so large because the satellites are not as close to the user.
(3) Positioning mode switching detection subunit
The time service type receiver selected by the invention can support various navigation positioning systems such as Beidou, GPS, Glonass, Galileo, QZSS and the like, and support to select one or more systems for positioning. At present, deception jamming mostly deceives GPS and Beidou signals, and deception of Glonass, Galileo and QZSS systems is less common. The system can be used for positioning by ordering the control receiver to poll and adopt the above systems alone, if the positions are consistent, the signals are normal, and if the positions specified by different systems have large deviation (for example, more than 10 kilometers), the satellite signals of some systems can be considered as deceptive signals.
(4) Pseudo-range rate of change detection subunit
Since spoofed sources of interference are generally fixed, the pseudorange observations, while modeling the motion of the satellites, are difficult to predict changes in pseudorange observations made to the user because of uncertainty in the position of the user relative to the pseudorange observations. Therefore, detailed analysis of the change of the pseudo-range observed quantity of a plurality of satellites can judge whether the deception jamming exists according to whether the change accords with the movement direction of the satellite relative to the receiver.
(5) Inertial navigation joint detection subunit
The inertial navigation module can output nine-axis motion information of the equipment in real time, and speed information in three directions output by inertial navigation is extracted and compared with speed information output by a navigation receiver, and inertial navigation is difficult to cheat; therefore, if the receiver is spoofed, there may be errors or mistakes in the navigation receiver obtaining velocity information from the position difference of the position fixes at different times. A certain error threshold may be set to detect whether spoofed interference is present.
(6) Least squares redundancy detection subunit
A spoofing interferer typically does not transmit all of the navigation satellite signals, but may selectively transmit some of the satellite signals; at this point, both the spoofed signal and the true signal are received by the receiver. The four satellites can realize positioning and time service by adopting a least square algorithm, and because the receivable satellite signals can normally reach dozens of satellites, if the satellite signals are real signals, the positioning results of any four satellites are not very different. If there are true signals and also spoofed signals, the positioning result is inconsistent, and whether there is spoofing interference is detected by determining a position every four satellites and calculating the position for multiple times in a redundant manner.
(7) Spoofing jammer decision subunit
According to the detection results of the six detection subunits, the risk level with deception interference is comprehensively judged and given out, and the risk level is output to the outside through alarm information for a user to make a decision, for example, the user can adopt processing modes of abandoning a satellite navigation positioning system, selecting timing results of a short wave system and a long wave system, and the like.
Specifically, the time and frequency processing module comprises a multi-phase-locked loop sub-module, a multi-phase counter and a loop filter; the multiphase phase-locked loop sub-module is used for generating a plurality of frequency signals with different phases.
As an implementable mode, the functions of the multimode information fusion module, the time and frequency processing module and the time signal interface protocol module are realized by an FPGA processor, and the FPGA adopts the domestic Shanghai Redan microelectronic FMK 50. The time-frequency processing mainboard is independently designed based on the high-speed FPGA, and the processing and coding of internal time information adopt a full FPGA processing realization mode; the problem of instability after the embedded processor and the like load the operating system can be avoided, and the stability and the reliability of the equipment are improved. A high-performance time frequency processing algorithm is adopted; the high-speed multi-order phase locking technology is adopted, and multi-phase clock signals are combined to process time and frequency, so that the precision and the performance of the equipment are improved. Adopting a high-speed processing clock rate; the internal processing clock reaches 320MHz, so that the precision of the equipment is ensured. The main board has the most important function that 1PPS given by the navigation module is used for taming the rubidium atomic clock, then the accurate frequency of the rubidium atomic clock is adopted to regenerate new 1PPS, and through the processing, the precision of the 1PPS with the precision of 20ns (RMS) output by the navigation module can be improved to be within 10ns (RMS), so that the requirement of indexes on time precision is met. Meanwhile, Irig-B codes are coded, and FPGA is adopted for coding, so that the real-time property and the accuracy of coding and the synchronism of each output can be ensured.
Specifically, as shown in fig. 5, the time and frequency processing module and the frequency control module perform processing on the frequency signal as follows:
a. the frequency output by the crystal oscillator/atomic clock is not only used by the FPGA, but also multiplexed to the outside; therefore, firstly, a low-noise amplifier is adopted to amplify the frequency signal output by the crystal oscillator/atomic clock, a power divider is adopted to divide the frequency signal, one path is sent to a multi-phase-locked loop sub-module (FPGA), and the other paths are output to the outside;
b. the 10MHz frequency signal input into the FPGA enters a multi-phase-locked loop in the FPGA, and is multiplied to 320MHz (the higher the frequency is, the higher the precision is; the 320MHz is the higher frequency which can be stably operated by the selected FPGA). The multi-phase-locked loop simultaneously outputs a plurality of 320MHz frequency signals with different phases, such as 6 frequency signals with different phases of 0 phase, 60 phase, 120 phase, 180 phase, 240 phase and 300 phase, and simultaneously outputs a path of 320MHz frequency signal to other modules in the FPGA, such as a multi-mode information fusion module;
c. inputting a plurality of clock signals with different phases into a multi-phase counter, and counting the externally input original 1PPS respectively;
d. averaging the counting values of different phase frequencies to obtain a counting average value;
e. calculating the error of the counting value through the counting average value and the ideal counting value; if both frequency and 1PPS are ideal, then the count value should be 320M (0-319999999 counts), so the ideal count value should be 320M. However, due to the frequency and inaccuracy of 1PPS, the count value is not an ideal value, and for 1PPS, although it is not accurate every time, its average value is accurate over a long period of time. Therefore, the difference between the average value of the count and the ideal count value in the long term is caused by frequency inaccuracy, and the difference is the error of the count value;
f. the error value of the count value is averaged for a long time through a loop filter to obtain the correction quantity of the frequency parameter;
g. converting the correction quantity of the frequency parameter into DA control quantity through a certain proportion; specifically, the ratio differs depending on each crystal oscillator;
h. outputting the DA control quantity to a high-precision DA;
i. the high-precision DA generates an analog voltage control signal, controls the frequency of the crystal oscillator/atomic clock, changes the output frequency, and corrects the frequency value of the closed loop until the error of the count value approaches to 0.
Through the process, the frequency of an external crystal oscillator or rubidium atomic clock is corrected to be more accurate 10MHz, so that a high-precision and high-accuracy frequency signal can be provided for the outside; meanwhile, the frequency signals inside the FPGA are accurate and reliable, and the performance of the system can be ensured when 1PPS fusion processing and timekeeping are carried out.
As an implementable embodiment, the hardware architecture of the present invention is as shown in fig. 6, and mainly includes a front panel, a host, a rear panel, and the like, where the front panel mainly includes a power switch, an LED indicator for indicating a basic operating state, and an interface for outputting time and frequency signals to the outside. The function and design of the modules are as described in the above embodiments.
In conclusion, the invention has the following beneficial effects:
(1) time service technology based on integration of satellite navigation positioning system and three time service modes of long wave and short wave
The reliability and the stability of the whole equipment can be improved by the three time service modes. In the design process, the short-wave time service and the long-wave time service are corrected by using the satellite navigation time service with the highest precision instead of simple three-mode selection, so that error parameters of the two time service modes with the poor precision are obtained, and the confidence coefficients of the two time service modes are given according to the stability of errors. The best second selection can be selected when satellite navigation time service is unavailable. Meanwhile, high-speed and high-precision frequency signal processing is carried out, the accuracy of output frequency is improved, and the time keeping precision and the internal signal processing precision when three time service modes are unavailable are also improved.
(2) Integrated anti-interference technology based on antenna, signal processing and data post-processing
The time-domain equipment takes the anti-interference technology as a key point, and systematically designs an anti-interference scheme. The method adopts the array antenna technology to form the beam zero point from the airspace to resist the strong suppression interference, and selects the time service type receiver submodule capable of inhibiting the narrow-band interference from the frequency domain in the selection of the time service type navigation module. For the deception jamming which is most sensitive to the satellite navigation positioning system, the deception jamming detection is carried out by adopting six modes of power consistency detection, power normality detection, positioning mode switching detection, pseudo-range change rate detection, inertial navigation joint detection, least square redundancy detection and the like so as to prevent the whole system from being deceased due to deception of the first selected satellite navigation time service.
(3) Highly autonomous controllable technology based on localization of main module
The invention starts from the architecture of software and hardware, comprehensively and carefully designs a localization scheme, and initially selects the type of components. The quantity and price ratio of the domestic components reach more than 90 percent.
The above shows only the preferred embodiments of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.
Claims (7)
1. An autonomous controllable multimode anti-interference time system device is characterized by comprising a time-frequency signal receiver module, a multimode information fusion module, a time and frequency processing module, a time signal interface protocol module, an interface conversion module, a frequency control module, a man-machine interaction module, a self-checking module and a power supply module;
the time-frequency signal receiver module is used for receiving the time information of the short wave, the long wave and the navigation satellite, wherein the time information comprises 1PPS, UTC and state information, and inputting the time information into the multimode information fusion module;
the multimode information fusion module is used for fusing the time information, and comprises UTC time signal comparison and 1PPS time signal fusion and optimization;
the time and frequency processing module is used for correcting the frequency by using the optimized 1 PPS;
the time signal interface protocol module is used for converting UTC and 1PPS time signal interface protocols according to requirements;
the interface conversion module is used for realizing level conversion and network interface functions;
the frequency control module is used for controlling the frequency information output by the time and frequency processing module;
the human-computer interaction module comprises a display control module and a touch screen and is used for human-computer interaction;
the self-checking module is used for realizing detection of each module and formation of error codes in the starting and working processes, and the detection result is displayed through the display control module;
the power module is used for converting an input 220VAC signal into a 24VDC signal for the whole device to use.
2. The autonomous controllable multimode anti-interference time system device according to claim 1, wherein the time-frequency signal receiver module comprises a short-wave receiver submodule, a long-wave receiver submodule and a time-service receiver submodule, the short-wave receiver submodule comprises a short-wave receiver, the long-wave receiver submodule comprises a long-wave receiver, the time-service receiver submodule comprises a time-service receiver, an anti-interference antenna and an anti-spoofing interference processing unit, and the anti-spoofing interference processing unit is configured to detect spoofing interference through post-processing of output information of the time-service receiver and output alarm information to the outside.
3. The autonomous controllable multimode anti-interference time system device according to claim 2, wherein said multimode information fusion module comprises a UTC processing sub-module, a short wave 1PPS processing sub-module, a long wave 1PPS processing sub-module, a 1PPS timekeeping sub-module, a synthesis 1PPS sub-module;
the UTC processing submodule is used for checking and comparing the universal coordination time obtained by the three receivers, selecting correct UTC and outputting the state whether the UTC time of the three receivers is consistent to the outside;
the short wave 1PPS processing submodule is used for correcting the error of the 1PPS of the short wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the short wave receiver through smooth filtering, outputting 1PPS of the short wave receiver after correcting the error, and giving a confidence coefficient parameter of the short wave receiver according to the stability of the error for a subsequent 1PPS synthesis submodule to use;
the long wave 1PPS processing submodule is used for correcting the error of the 1PPS of the long wave receiver by using the 1PPS of the time service type receiver when the 1PPS of the time service type receiver is effective; obtaining an accumulative average error value of 1PPS of the long wave receiver through smooth filtering, outputting 1PPS of the long wave receiver after correcting the error, and providing a confidence coefficient parameter of the long wave receiver for a subsequent synthesis 1PPS sub-module according to the stability of the error;
the 1PPS time keeping submodule is used for keeping time for the 1PPS acquired by the time service type receiver, and when the time service type receiver is invalid, counting and keeping the time service type receiver by adopting a disciplined accurate clock;
the synthesis 1PPS submodule is used for selecting 1PPS input by three receivers, the first selection is 1PPS output by a time service type receiver, the second selection and the third selection are respectively to select 1PPS output by a long wave receiver after error correction and 1PPS output by a short wave receiver after error correction according to confidence coefficient parameters of the long wave receiver and the short wave receiver, and the fourth selection is 1PPS output by a 1PPS time keeping submodule; the synthesize 1PPS sub-module is also used to smooth filter the selected 1PPS with the exact clock that has been disciplined.
4. The autonomous controllable multimode anti-interference time system device according to claim 1, wherein the frequency control module comprises a high-precision DA, a crystal oscillator/atomic clock, an amplifier, and a power divider, and the high-precision DA, the crystal oscillator/atomic clock, the amplifier, and the power divider are connected in sequence.
5. The autonomous controllable multimode interference-resistant time system device according to claim 2, wherein the anti-spoofing interference processing unit comprises a power consistency detection subunit, a power normality detection subunit, a positioning mode switching detection subunit, a pseudo-range change rate detection subunit, an inertial navigation joint detection subunit, a least square redundancy detection subunit, and a spoofing interference decision subunit.
6. An autonomous controllable multimode interference rejection time system device according to claim 4, characterized in that said time and frequency processing module comprises a multi-phase-locked loop sub-module, a multi-phase counter and a loop filter.
7. The autonomous controllable multimode interference rejection time system device according to claim 6, wherein said time and frequency processing module and said frequency control module perform frequency signal processing specifically as follows:
a. amplifying a frequency signal output by a crystal oscillator/atomic clock by using a low-noise amplifier, and shunting the frequency signal by using a power divider, wherein one path is supplied to a multi-phase-locked loop submodule, and the other paths are output to the outside;
b. the frequency signal input to the multi-phase-locked loop submodule is subjected to frequency multiplication, and the multi-phase-locked loop submodule simultaneously outputs a plurality of clock signals with different phases;
c. inputting a plurality of clock signals with different phases into a multi-phase counter, and counting the externally input original 1PPS respectively;
d. averaging the counting values of different phase frequencies to obtain a counting average value;
e. calculating the error of the counting value through the counting average value and the ideal counting value;
f. the error value of the count value is averaged for a long time through a loop filter to obtain the correction quantity of the frequency parameter;
g. converting the correction quantity of the frequency parameter into a DA control quantity;
h. outputting the DA control quantity to a high-precision DA;
i. the high-precision DA generates an analog voltage control signal, controls the frequency of the crystal oscillator/atomic clock, and changes the output frequency until the error of the count value approaches 0.
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