CN112433231B - Space-time reference equipment of vehicle-mounted platform - Google Patents

Abstract

The invention discloses space-time reference equipment of a vehicle-mounted platform, which comprises a power switch, an LED indicator light, a high-stability power module, a time-frequency processing mainboard, a rubidium atomic clock, a 10MHz low-noise amplifier, a power divider, a directional navigation receiver, a raspberry pi and an RS422 difference module; the high-stability power module is simultaneously electrically connected with the time-frequency processing mainboard and the rubidium atomic clock, the 10MHz low-noise amplifier and the power divider are sequentially electrically connected, and the time-frequency processing mainboard is simultaneously electrically connected with the rubidium atomic clock, the power divider, the directional navigation receiver, the raspberry pie and the RS422 difference module; the high-stability power supply module is also electrically connected with a power supply interface, the directional navigation receiver is also electrically connected with two antenna interfaces, the raspberry pi is electrically connected with a network port, the RS422 differential module is electrically connected with a 1PPS and B code output port, and the power divider is electrically connected with a 10MHz frequency output port; the method has the advantages of improving the positioning precision and providing accurate information to users in various interface forms.

Description

Space-time reference equipment of vehicle-mounted platform

Technical Field

The invention relates to the field of space-time positioning, in particular to space-time reference equipment of a vehicle-mounted platform.

Background

In recent years, vehicle-mounted navigators are rapidly developed in the field of automobiles, great convenience is brought to travel of people, and as long as a driver inputs a travel destination into the vehicle navigator, the navigator can automatically guide the driver to travel to a set destination; meanwhile, the navigator can also provide time, position and other information for a driver, but the conventional vehicle-mounted navigator generally has time delay in the process from receiving the positioning information of the satellite to displaying, is not high enough in precision, and cannot realize real-time positioning.

The present invention therefore provides a space-time reference apparatus for a vehicle platform that addresses the above-identified problems.

Disclosure of Invention

The technical problem to be solved by the invention is that the existing vehicle-mounted navigator generally has time delay in the process from receiving positioning information of a satellite to displaying, and meanwhile, the precision is not high enough, so that real-time positioning cannot be realized; there is provided a space-time reference apparatus of a vehicle-mounted platform, the space-time reference apparatus of the vehicle-mounted platform including:

the device comprises a power switch, an LED indicator light, a high-stability power module, a time-frequency processing mainboard, a rubidium atomic clock, a 10MHz low-noise amplifier, a power divider, a directional navigation receiver, a raspberry pi and an RS422 difference module;

the high-stability power module is simultaneously electrically connected with the time-frequency processing mainboard and the rubidium atomic clock, the 10MHz low-noise amplifier and the power divider are sequentially electrically connected, and the time-frequency processing mainboard is simultaneously electrically connected with the rubidium atomic clock, the power divider, the directional navigation receiver, the raspberry pi and the RS422 difference module;

the high-stability power module is further electrically connected with a power interface, the directional navigation receiver is further electrically connected with two antenna interfaces, the raspberry pi is electrically connected with a network port, the RS422 differential module is electrically connected with a 1PPS and B code output port, and the power divider is electrically connected with a 10MHz frequency output port.

Further, the time-space reference device of the vehicle-mounted platform provided by the application, wherein the time-frequency processing mainboard comprises a multi-mode information fusion module, a multi-phase-locked loop, a frequency control module, a pulse per second generation module and a UTC coding module, the multi-mode information fusion module is electrically connected with the frequency control module, the pulse per second generation module and the UTC coding module at the same time, the input end of the multi-phase-locked loop is electrically connected with the rubidium atomic clock, the output end of the multi-phase-locked loop is electrically connected with the frequency control module, the pulse per second generation module and the UTC coding module are electrically connected with the RS422 difference module at the same time, and the multi-mode information fusion module is electrically connected with the directional navigation receiver.

Further, the space-time reference equipment of the vehicle-mounted platform provided by the application comprises a pulse-per-second phase calibration unit and a UTC time extraction unit, wherein the multimode information fusion module further comprises a pulse-per-second phase calibration unit and a UTC time extraction unit;

the pulse per second phase calibration unit is used for receiving serial port information of the directional navigation receiver, optimizing the serial port information and sending the optimized serial port information to the pulse per second generation module and the frequency control module;

and the UTC time extraction unit is used for receiving the UTC time and ensuring the timely leap second processing.

Further, the application provides a space-time reference device for a vehicle-mounted platform, wherein the multi-phase-locked loop is used for improving the processing accuracy of the frequency control module.

Further, the space-time reference equipment of the vehicle-mounted platform provided by the application is characterized in that the pulse-per-second generation module is used for receiving the serial port information after the optimization processing and generating 1pps based on the serial port information after the optimization processing.

Further, the space-time reference equipment of the vehicle-mounted platform provided by the application is characterized in that the UTC encoding module is used for encoding and performing protocol processing on UTC information.

Further, the space-time reference equipment of the vehicle-mounted platform is provided, wherein the high-stability power module is used for providing power for the space-time reference equipment of the vehicle-mounted platform.

Furthermore, the raspberry group is used for processing data and data protocols, and NTP network time service is realized through the network port;

the raspberry pie is also used for outputting the complete machine state and data of the space-time reference equipment of the vehicle-mounted platform and controlling parameter input.

Further, the application provides a space-time reference equipment of vehicle platform, wherein, directional navigation receiver is high accuracy PTK location orientation device.

The implementation of the invention has the following beneficial effects:

1. the invention adopts a high-power linear power supply, ensures output power and simultaneously has good efficiency and ripple characteristics, adopts a multi-phase-locked loop, can improve the processing precision of a frequency control module, adopts a high-performance rubidium atomic clock as a frequency source, adopts double antennas for direction finding, and can provide accurate information such as position, time, speed, course, posture and the like for users in a plurality of interface forms.

Drawings

FIG. 1 is a block diagram of a space-time reference device of a vehicle platform according to the present invention;

FIG. 2 is a block diagram of a time-frequency processing motherboard of the time-space reference device of the vehicle-mounted platform according to the present invention;

FIG. 3 is a flow chart of the accuracy of the processing of the multiphase phase locked loop enhanced frequency control module in the space-time reference device of the vehicle platform according to the present invention;

FIG. 4 is a same-frequency multi-phase clock diagram generated by a phase-locked loop in the space-time reference device of the vehicle-mounted platform according to the present invention.

Wherein: 1. a power switch; 2. an LED indicator light; 3. a high-stability power supply module; 4. a time-frequency processing mainboard; 401. a multimode information fusion module; 4011. a pulse per second phase calibration unit; 4012. a UTC time extraction unit; 402. a multi-phase-locked loop; 403. a frequency control module; 404. a pulse per second generation module; 405. a UTC encoding module; 5. a rubidium atomic clock; 6. a 10MHz low noise amplifier; 7. a power divider; 8. a directional navigation receiver; 9. a raspberry pie; 10. RS422 difference module.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

Examples

In the embodiment, referring to fig. 1 to 4 of the specification, the technical problem to be solved in the embodiment is that the existing vehicle-mounted navigator generally has a time delay in the process from receiving positioning information of a satellite to displaying, and meanwhile, the accuracy is not high enough, so that real-time positioning cannot be realized; there is provided a space-time reference apparatus of a vehicle-mounted platform, the space-time reference apparatus of the vehicle-mounted platform including:

the device comprises a power switch 1, an LED indicator lamp 2, a high-stability power module 3, a time-frequency processing mainboard 4, a rubidium atomic clock 5, a 10MHz low-noise amplifier 6, a power divider 7, a directional navigation receiver 8, a raspberry pi 9 and an RS422 difference module 10;

the high-stability power module 3 is simultaneously and electrically connected with the time-frequency processing mainboard 4 and the rubidium atomic clock 5, the 10MHz low-noise amplifier 6 and the power divider 7 are sequentially and electrically connected, and the time-frequency processing mainboard 4 is simultaneously and electrically connected with the rubidium atomic clock 5, the power divider 7, the directional navigation receiver 8, the raspberry pie 9 and the RS422 difference module 10;

the high-stability power module 3 is further electrically connected with a power interface, the directional navigation receiver 8 is further electrically connected with two antenna interfaces, the raspberry pi 9 is electrically connected with a network port, the RS422 differential module 10 is electrically connected with a 1PPS and B code output port, and the power divider 7 is electrically connected with a 10MHz frequency output port;

the video processing mainboard provided by the embodiment is mainly a time-frequency processing mainboard which is independently designed based on a 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), and the requirement of indexes on time precision is met. Meanwhile, irig-B codes are coded, and an 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;

in order to ensure the stability and reliability of the power supply of the whole machine, the embodiment adopts a high-power linear power supply, so that the output power is ensured, and meanwhile, the high-power linear power supply has good efficiency and ripple characteristics;

the 10MHz low noise amplifier in the embodiment amplifies the power of 10MHz frequency input by the rubidium atomic clock to 16.5-18 dBm, and then outputs a frequency signal through the power divider;

the Raspberry Pi computer board is used for processing data and data protocols, realizing NTP network time service through a 100M/1000M self-adaptive network port, and carrying out interaction such as output of the whole machine state and data, input of control parameters and the like.

In a specific embodiment, the time-frequency processing motherboard 4 includes a multi-mode information fusion module 401, a multi-phase-locked loop 402, a frequency control module 403, a pulse per second generation module 404, and a UTC coding module 405, the multi-mode information fusion module 401 is electrically connected to the frequency control module 403, the pulse per second generation module 404, and the UTC coding module 405 at the same time, an input end of the multi-phase-locked loop 402 is electrically connected to the rubidium atomic clock 5, an output end of the multi-phase-locked loop is electrically connected to the frequency control module 403, the pulse per second generation module 404 and the UTC coding module 405 are electrically connected to the RS422 difference module 10 at the same time, and the multi-mode information fusion module 401 is electrically connected to the directional navigation receiver 8.

In a specific embodiment, the multimode information fusion module 401 further includes a pulse per second phase calibration unit 4012 and a UTC time extraction unit 4011;

the pulse per second phase calibration unit 4012 is configured to first determine whether 1pps generated by the GPS/beidou time service type navigation receiver is available; receiving serial port information of an NMEA protocol from a GPS/Beidou time service type navigation receiver, judging whether the receiver has received enough satellite signals or not through the serial port information, and finishing positioning and timing work, wherein if the positioning and timing are finished and the GDOP of a satellite for positioning and timing is less than 5, 1pps available information generated by the GPS/Beidou time service type navigation receiver is given, and if not, the information is unavailable;

performing fusion processing on available 1pps, performing balance filtering processing on 1pps signals of each module to reduce random errors, and then performing adjustment optimization on 1pps signals from a plurality of modules by adopting a least square algorithm to obtain more accurate phase 1pps signals to serve as the basis of subsequent processing;

the UTC time extraction unit is used for comparing UTC time from the modules to ensure the accuracy of UTC, and integrating and comparing leap second information from the modules to ensure timely leap second processing.

In a specific embodiment, the multi-phase-locked loop is configured to perform frequency multiplication on a 10MHz frequency signal generated by a high-stability constant-temperature crystal oscillator by using a phase-locked loop inside an FPGA, and generate a plurality of same-frequency phase-shifted clocks as shown in fig. 4 by using a characteristic that the phase-locked loop can generate a plurality of phases with the same frequency. The method comprises the steps of utilizing the count average value to count 1pps after phase correction all the time simultaneously, then averaging the technical values to obtain a count average value, utilizing the count average value to be used as an actual count value and a theoretical count value to compare to obtain a count error, for example, a 200MHz clock which is multiplied by frequency by 20 to 4 phases of an input frequency of 10MHz, wherein due to inaccuracy of frequency generated by a crystal oscillator, the count values of 4 clocks to the input 1pps are 200000010, 200000011, 200000011 and 200000011 respectively, then the average count value is 200000010.75, and the ideal count value is 200000000, then the count error value is 10.75, obtaining a high-precision voltage control value for controlling the frequency of the crystal oscillator after a plurality of historical count values pass through a loop filter, converting the high-precision count value into a DA control quantity, sending the DA control quantity to a high-precision DA, converting a control signal into a voltage signal to control the frequency of the high-stability crystal oscillator, gradually adjusting the frequency of the crystal oscillator until the count error reaches the requirement, actually, and carrying out a dynamic constant-temperature adjustment process is carried out.

The traditional frequency control method is that a common-frequency clock with a plurality of phases is sampled to count 1pps at the same time, the counting mode is equivalent to the mode of increasing the counting frequency, for example, 4 multiphase clocks with 200MHz are used for counting, and one clock with 800MHz is used for counting, so that the counting precision is greatly improved, and the control precision of a crystal oscillator is correspondingly improved.

In a specific embodiment, the pulse-per-second generation module is configured to regenerate 1pps with high precision and high stability based on the corrected 1pps and the high-accuracy frequency signal. When 1pps of the navigation receiver is available and multimode correction is carried out, the 1pps is used as a basic phase source, a high-precision frequency is used as a counting source at intervals of 1pps, and new 1pps is generated, wherein the 1pps has the characteristics of accurate phase and accurate interval.

Under the condition that satellite navigation signals are normal, the system can obtain a more accurate phase of 1pps after working for a period of time, and controls the error of the high-stability constant-temperature crystal oscillator within a smaller range, namely after the crystal oscillator is acclimated, the system informs the outside that the time can be conserved. In this case, if all the satellite navigation receiver signals are blocked or interfered and 1pps thereof is not available, the system enters a time keeping state, the second pulse generating and holding module enters a time keeping mode, 1pps is generated at the existing phase and frequency of 1pps, and the exterior is informed that the time keeping mode is currently adopted.

In a specific embodiment, the UTC encoding module is configured to perform different encoding and protocol processing on UTC information to adapt to different external interfaces, and the main encoding module includes a network interface of an NTP protocol for network time service; IRIG-B and NMEA are encoded serially.

In a specific embodiment, the high-stability power module is used for supplying power to the space-time reference device of the vehicle-mounted platform.

In a specific embodiment, the directional navigation receiver selects a BDS/GPS/GLONASS/Galileo high-precision RTK positioning and orientation module. Adopting an FPGA to discipline the 1PPS pair rubidium atomic clock given by the navigation module to an accurate frequency; then, a new 1PPS is generated again by using the accurate frequency of the rubidium atomic clock, and the precision of the 1PPS with the precision of 20ns (RMS) output by the navigation module can be improved to be within 10ns (RMS) (the actual measurement is less than 6ns (RMS)).

The implementation principle is as follows:

the directional navigation receiver receives satellite signals of Beidou/GPS/GLONASS to realize positioning, timing and directional functions, the directional navigation receiver realizes the directional function through two antennas, and the module sends information such as position, time, 1PPS (pulse per second), direction and the like to the time-frequency processing mainboard.

The method comprises the steps that 1PPS is smoothed by a time-frequency processing main board and then sent to a rubidium atomic clock, the rubidium atomic clock utilizes the 1PPS to calibrate frequency and output an accurate 10MHz frequency signal, meanwhile, the selected rubidium atomic clock can also output the corrected and smoothed 1PPS, the stability and accuracy of the 1PPS are superior to those of the 1PPS originally output by a navigation module, and the 1PPS with the precision of 20ns (RMS) output by the navigation module can be improved to be within 10ns (RMS). And 1PPS output by the rubidium atomic clock is input into a time frequency processing mainboard.

And combining the externally input 1PPS initial phase correction parameter to serve as the finally output 1PPS, and inputting the 1PPS into an RS422 difference module to realize the RS422 or TTL output of the 1PPS. And in the time-frequency processing mainboard, IRIG-B DC coding is carried out according to the time information and 1PPS, and the IRIG-B DC coding is input into an RS422 differential module to realize RS422 or TTL output of IRIG-B codes.

After the 10Mhz frequency signal after being domesticated is amplified by a low-noise amplifier, 10 paths are divided by a power divider, 1 path is input into the FPGA, 8 paths are output to the outside, and 1 path is not used for absorption.

The implementation of the invention has the following beneficial effects:

1. the invention adopts a high-power linear power supply, ensures output power and has good efficiency and ripple characteristics, adopts a multi-phase-locked loop, can improve the processing precision of a frequency control module, adopts a high-performance rubidium atomic clock as a frequency source, adopts double antennas for direction finding, and can provide accurate information such as position, time, speed, course, posture and the like for users in various interface forms.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (8)

1. A space-time reference apparatus for a vehicle-mounted platform, comprising: the device comprises a power switch (1), an LED indicator lamp (2), a high-stability power module (3), a time-frequency processing mainboard (4), a rubidium atomic clock (5), a 10MHz low-noise amplifier (6), a power divider (7), a directional navigation receiver (8), a raspberry pie (9) and an RS422 difference module (10);

the high-stability power module (3) is simultaneously and electrically connected with the time-frequency processing mainboard (4) and the rubidium atomic clock (5), the 10MHz low-noise amplifier (6) and the power divider (7) are sequentially and electrically connected, and the time-frequency processing mainboard (4) is simultaneously and electrically connected with the rubidium atomic clock (5), the power divider (7), the directional navigation receiver (8), the raspberry pie (9) and the RS422 difference module (10);

the high-stability power supply module (3) is also electrically connected with a power supply interface, the directional navigation receiver (8) is also electrically connected with two antenna interfaces, the raspberry pi (9) is electrically connected with a network port, the RS422 difference module (10) is electrically connected with a 1PPS and B code output port, and the power divider (7) is electrically connected with a 10MHz frequency output port;

the directional navigation receiver is a high-precision PTK positioning and directional device.

2. The space-time reference equipment of the vehicle-mounted platform according to claim 1, wherein the time-frequency processing mainboard (4) comprises a multi-mode information fusion module (401), a multi-phase-locked loop (402), a frequency control module (403), a pulse per second generation module (404) and a UTC coding module (405), the multi-mode information fusion module (401) is electrically connected with the frequency control module (403), the pulse per second generation module (404) and the UTC coding module (405) at the same time, an input end of the multi-phase-locked loop (402) is electrically connected with the rubidium atomic clock (5), an output end of the multi-phase-locked loop is electrically connected with the frequency control module (403), the pulse per second generation module (404) and the UTC coding module (405) are electrically connected with the RS422 difference module (10) at the same time, and the multi-mode information fusion module (401) is electrically connected with the directional navigation receiver (8).

3. The space-time reference device of the on-board platform according to claim 2, wherein the multimode information fusion module (401) further comprises a pulse-per-second phase calibration unit (4012) and a UTC time extraction unit (4011);

the second pulse phase calibration unit (4012) is used for receiving serial port information of the directional navigation receiver (8), optimizing the serial port information, and sending the optimized serial port information to the second pulse generation module and the frequency control module;

and the UTC time extraction unit (4011) is used for receiving UTC time and ensuring that leap second processing is carried out in time.

4. The space-time reference device of the vehicle-mounted platform according to claim 3, wherein the multi-phase-locked loop is used for improving the processing accuracy of the frequency control module.

5. The space-time reference device of the vehicle-mounted platform according to claim 4, wherein the pulse-per-second generation module is configured to receive the optimized serial port information and generate 1pps based on the optimized serial port information.

6. The space-time reference apparatus of an in-vehicle platform according to claim 5, wherein the UTC encoding module is configured to encode and protocol UTC information.

7. The space-time reference device of vehicle-mounted platform as claimed in claim 6, wherein the high-stability power module is used for providing power to the space-time reference device of vehicle-mounted platform.

8. The space-time reference device of the vehicle-mounted platform according to claim 7, wherein the raspberry pi is used for processing data and data protocols, and NTP network time service is realized through the network port;

the raspberry pie is also used for outputting the complete machine state and data of the space-time reference equipment of the vehicle-mounted platform and controlling parameter input.

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