A method to improve the accuracy of earth observation by atmospheric detection payload

Abstract

The present invention provides a method for improving the accuracy of earth observation by atmospheric detection payloads, comprising the following steps: synchronously correcting different atmospheric detection payloads; synchronously correcting multiple detection channels of atmospheric detection payloads; and synchronously correcting the observation angle, data collection time, and satellite parameters of atmospheric detection payloads. Beneficial effects of the present invention: observation scanning of the same observation target by different atmospheric detection payloads of commercial satellites adopts a method of eliminating errors by synchronizing multiple physical signals and monitoring software, thereby eliminating the delay of time broadcasting by different detection payloads of traditional satellites through CAN bus or 1553 bus, the time observation error caused by data reception, and the observation error between different detection channels and different collection points, thereby improving the accuracy of data acquisition of the same observation target by different detection payloads.

Description

Technical Field

[0001] The invention belongs to the technical field of earth observation accuracy of atmospheric detection payloads, and in particular relates to a method for improving the earth observation accuracy of atmospheric detection payloads. Background Art

[0002] Atmospheric temperature, humidity and atmospheric water vapor are important parameters for weather analysis and weather forecasting. Obtaining high-precision atmospheric temperature, humidity and water vapor parameters not only helps to achieve accurate numerical weather forecasts, but also can achieve real-time forecasts of severe convective weather. Since atmospheric temperature, humidity and atmospheric water vapor detection are detected by different remote sensing detection payloads, the resolution of different detection payloads and the range of ground scanning are inconsistent. Weather analysis and weather forecasting require two payloads to jointly process and invert the data of atmospheric parameters observed at the same time. At present, different detection payloads use the method of aligning the broadcast time on the satellite to keep the scanning synchronization of the two instruments and equipment. There are transmission delays and reception delays in the on-board broadcast time. On the other hand, with the continuous improvement of the resolution of ground observation, the channels for atmospheric temperature, humidity and atmospheric water vapor detection payloads are constantly increasing, and there are also sampling timing deviations between different detection channels, which leads to deviations in ground observation. On the other hand, different observation points for ground observation need to use angle information to mark the specific observation location. There are also deviations in the angle information of different observation points and the acquisition time of the observation points. The above deviations will lead to observation deviations between different detection channels, different acquisition points and different payloads. As the resolution of commercial satellite earth observation continues to improve, the problems caused by the above deviations have become increasingly prominent. It is necessary to adopt a method to improve earth observation and reduce the impact of the above deviations. Summary of the invention

[0003] In view of this, the present invention aims to propose a method for improving the accuracy of earth observation by atmospheric sounding payloads, so as to solve the problem that as the resolution of earth observation by commercial satellites continues to increase, the observation deviations between different detection channels, different collection points and different payloads of atmospheric temperature and humidity, atmospheric water vapor in commercial atmospheric sounding satellites have an increasingly serious impact on the accuracy of joint inversion of data processing and the accuracy of weather forecasts.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for improving the earth observation accuracy of an atmospheric detection payload comprises the following steps:

[0006] S1. Synchronous correction of different atmospheric detection payloads;

[0007] S2. Synchronize and correct multiple channels of atmospheric detection payloads;

[0008] S3, synchronously correcting the observation angle, data collection time, and satellite parameters of the atmospheric detection payload; in step S1, synchronously correcting different atmospheric detection payloads, including:

[0009] Define two atmospheric detection payloads, namely atmospheric detection payload A and atmospheric detection payload B;

[0010] A The atmospheric detection payload uses a constant temperature crystal oscillator to generate a 100M clock to collect the on-board time pulses sent by the satellite and the time information broadcast by the satellite;

[0011] Generate a 100M clock based on the local constant temperature crystal oscillator, generate a scan synchronization pulse and maintain an A atmospheric detection payload local time, and generate a scan synchronization pulse cycle based on the periodic scanning mode;

[0012] After receiving the scanning synchronization pulse generated by the A atmospheric detection payload, the B atmospheric detection payload uses a constant temperature crystal oscillator to generate a 100M clock, collects the scanning synchronization pulse, and simultaneously collects the time signal broadcast on the satellite to generate the scanning start pulse of the B atmospheric detection payload. The B atmospheric detection payload starts at T delayb Then start the observation scan;

[0013] At the same time, the B atmospheric detection payload will receive the scanning synchronization pulse generated by the A atmospheric detection payload and send the signal back to the A atmospheric detection payload. The A atmospheric detection payload will collect the transmission delay of the synchronization pulse sent and received by the A atmospheric detection payload, and generate the scanning start signal of the A atmospheric detection payload after time correction. The A atmospheric detection payload will start scanning at T delaya Then start the observation scan.

[0014] Furthermore, in step S1, the periodic scanning method includes:

[0015] Set the scanning period of the atmospheric detection payload A to M / N seconds, the scanning period of the atmospheric detection payload B to M seconds, and M seconds as the synchronization pulse period;

[0016] In this way, after every N ground scans, the A atmospheric detection payload and the B atmospheric detection payload will perform a scanning synchronization.

[0017] Furthermore, in step S1, the ground observation accuracy of atmospheric detection payload A and atmospheric detection payload B can be improved to the order of 0.5us, and the error of atmospheric detection payload A and atmospheric detection payload B is ±2 meters. Furthermore, in step S2, synchronous correction is performed between multiple channels of the atmospheric detection payload, including: the atmospheric detection payload uses a pair of ground observation antennas and simultaneously separates multi-channel detection signals;

[0018] Method for synchronous sampling and sampling error elimination of multi-channel ADC of multi-channel atmospheric detection payload;

[0019] The errors between multi-channel observations of atmospheric detection payloads and between multi-channel ADC sampling are eliminated by the quadratic error elimination method.

[0020] Furthermore, in step S2, the registration accuracy of the multi-channel observation signal of the atmospheric detection payload can be improved to ±0.001°.

[0021] Furthermore, in step S2, the sampling error elimination method includes:

[0022] The clock phase compensation correction is performed on the sampling clocks of multiple ADCs. Multiple ADCs sample the same type of observation targets and evaluate the delay of different sampling channels.

[0023] The delay information of different channels and the input of the ADC sampling clock delay circuit for different channels are sent to the atmospheric detection payload to start the observation scanning time T delaya , T delayb Correct the scan start time.

[0024] Further, in step S2, the secondary error elimination method includes:

[0025] The multi-channel ADC samples a ground observation point multiple times at a sampling rate i times higher than the normal sampling rate;

[0026] According to the relationship between different sampling points and the center position of this sampling point and after multiple calculations on the calibration source and the ground observation scan value, the weight value W of each sampling is set i ;

[0027] The sampling result C of each earth observation i And the corresponding weight value W i After multiplication, take the average of the operations and use the result as the result of this sampling C j At the same time, the angle and time information values ​​of the (i-1) / 2th sampling in the i sampling of this earth observation are used as the position and time mark of this earth observation.

[0028] Furthermore, in step S3, the observation angle of the atmospheric detection payload, the data collection time, and various satellite parameters are synchronously corrected, including:

[0029] Earth observation uses an angle measurement sensor with a 25-bit resolution. The angle measurement sensor has a conversion time T when measuring the angle. C At the same time, there is a transmission delay T in the process of the angle sensor transmitting to the earth observation acquisition control circuit. d ;

[0030] There is also a time delay T from ADC sampling to the remote sensing data packet packaging circuitADC , the parameters transmitted by the satellite also have a time error T sat ;

[0031] The remote sensing data packet packaging circuit generates a 100MHz clock based on the local constant temperature crystal oscillator, collects the angle information transmitted by the angle sensor, and converts the T C +T d To correct the time, collect the on-board time synchronization pulse sent by the satellite, and collect the time information broadcast by the satellite to maintain the local clock. Use this clock to collect the observation information transmitted by the ADC for time error T ADC Correction: the error T of each parameter information transmitted by the satellite sat make corrections;

[0032] The observation angle and observation position are corrected on the ground using the corresponding satellite parameter information.

[0033] Furthermore, in step S3, the satellite parameters include attitude information, position, and speed information. Compared with the prior art, the method for improving the earth observation accuracy of the atmospheric detection payload of the present invention has the following advantages:

[0034] (1) The method of improving the earth observation accuracy of atmospheric detection payloads described in the present invention adopts a method of multiple physical signal synchronization plus software monitoring error elimination for observation scanning of the same observation target by different atmospheric detection payloads of commercial satellites, thereby eliminating the delay of time broadcast through the CAN bus or 1553 bus of different detection payloads of traditional satellites and the time observation error caused by data reception, thereby improving the accuracy of data acquisition of the same observation target by different detection payloads.

[0035] (2) A method for improving the accuracy of earth observation of an atmospheric detection payload described in the present invention, wherein different channels of the atmospheric detection payload of a commercial satellite adopt a multi-channel ADC synchronous sampling and sampling error elimination method to ensure the sampling time accuracy of the same observation target between different channels, thereby reducing the earth observation error caused by the sampling time deviation of different channels, and ensuring the pointing accuracy and alignment accuracy of observations of different observation channels. (3) A method for improving the accuracy of earth observation of an atmospheric detection payload described in the present invention, wherein the commercial satellite atmospheric detection payload improves the accuracy of the earth scanning control motor at different observation points of the earth, and corrects the deviation of the transmitted angle information and the ADC sampling time, thereby further improving the consistency of the time information and angle information of the commercial satellite atmospheric detection payload at different observation points of the earth, and ensuring the accuracy of observation collection at different points. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of A / B atmospheric detection payload synchronization according to an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of synchronous correction of multi-channel sampling of an atmospheric detection payload according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the observation angle, collected data, and synchronous correction of various satellite parameters of the atmospheric detection payload according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] like Figures 1 to 3As shown, a method for improving the earth observation accuracy of an atmospheric detection payload comprises the following steps:

[0045] 1. Traditionally, different detection payloads synchronize the sampling time of different observation payloads through time broadcasting via the CAN bus or 1553 bus. The time broadcasting accuracy is 0.1ms. As the resolution of commercial satellite earth observations continues to improve, the time broadcasting accuracy and the time observation errors caused by data reception will lead to an error of 200 meters for earth observations at 530 km. This has a greater impact on atmospheric detection payloads with a resolution better than 100 meters. If two similar observation payloads are not synchronized, the error between the two atmospheric detection payloads will be ±200 meters, and the deviation range will be 400 meters, which will bring great difficulties to the subsequent data preprocessing. The observation scanning of the same observation target by different atmospheric detection payloads of commercial satellites adopts the method of multiple physical signal synchronization plus software monitoring error elimination to eliminate the delay of time broadcasting and data reception caused by different detection payloads of traditional satellites through the CAN bus or 1553 bus, thereby improving the accuracy of data acquisition of the same observation target by different detection payloads. Figure 1 As shown, first, the A atmospheric detection payload uses a short-term high-stability constant temperature crystal oscillator to generate a 100M clock to collect the on-board time pulses sent by the satellite, and at the same time collects the time information broadcast by the satellite. According to the local short-term high-stability constant temperature crystal oscillator, a 100M clock is generated to generate a scanning synchronization pulse and maintain a local time of the A atmospheric detection payload. The period of the scanning synchronization pulse is generated according to the following method. The scanning period of the A atmospheric detection payload is M / N seconds, and the scanning period of the B atmospheric detection payload is M seconds, with M seconds as the synchronization pulse period. In this way, after every N ground scans, the A atmospheric detection payload and the B atmospheric detection payload will perform a scanning synchronization. After the B atmospheric detection payload receives the scanning synchronization pulse generated by the A atmospheric detection payload, the B atmospheric detection payload uses a short-term high-stability constant temperature crystal oscillator to generate a 100M clock to collect the scanning synchronization pulse, and at the same time collects the time signal broadcast on the satellite to generate the scanning start pulse of the B atmospheric detection payload. The B atmospheric detection payload starts scanning at T delayb At the same time, the B atmospheric detection payload will receive the scanning synchronization pulse generated by the A atmospheric detection payload and send the signal back to the A atmospheric detection payload. The A atmospheric detection payload will collect the transmission delay of the synchronization pulse sent and received by the A atmospheric detection payload, and generate the scanning start signal of the A atmospheric detection payload after time correction. The A atmospheric detection payload will start scanning at T delaya Then the observation scan begins. The above method allows the atmospheric detection payload A and the atmospheric detection payload B to be synchronized after every N scans. Through the method of synchronizing multiple physical signals and eliminating software monitoring errors, the ground observation accuracy of the atmospheric detection payloads A and B can be improved to the 0.5us level, and the error of the two atmospheric detection payloads is ±2 meters.

[0046] 2. If Figure 2 The commercial satellite atmospheric detection payload shown uses a pair of earth observation antennas and simultaneously separates multiple detection signals, rather than using multiple observation antennas for observation, to eliminate the errors of the mechanical axis and antenna optical axis caused by different observation antennas from the source. The registration accuracy of the multi-channel observation signals can be improved to ±0.001°. On the above basis, the multi-channel ADC is synchronously sampled and the sampling error elimination method is performed to ensure the sampling time accuracy of the same observation target between different channels, thereby reducing the earth observation error caused by the sampling time deviation of different channels. The sampling clocks of the multi-channel ADCs are compensated and corrected for the clock phase. The multi-channel ADCs sample the same type of observation targets, evaluate the delay of different sampling channels, and input the delay information of different channels and the ADC sampling clock delay circuit for different channels. At the same time, the delay information is sent to the atmospheric detection payload to start the observation scan time T delaya , T delayb Based on the above error elimination method, the multi-channel ADC samples a ground observation point multiple times at a sampling rate i times higher than the normal sampling rate. According to the specific relationship between different sampling points and the center position of this sampling point and after multiple calculations on the calibration source and the ground observation scan value, the weight value W of each sampling is set. i , the sampling result C of each earth observation i And the corresponding weight value W i After multiplication, take the average of the operations and use the result as the result of this sampling C j At the same time, the angle and time information values ​​of the (i-1) / 2th sampling in the i sampling of this earth observation are used as the position and time mark of this earth observation. The above method further eliminates the errors between multi-channel observations and multi-channel ADC sampling, and further improves the registration accuracy between different channels of the earth. The earth observation accuracy of different channels can be improved to 0.5us level, and the error is controlled within ±2 meters.

[0047] 3. Such as Figure 3 The commercial satellite atmospheric detection payload shown in the figure improves the accuracy of the ground scanning control motor at different observation points on the ground, and the deviation of the transmitted angle information and the ground observation time needs to be corrected. The ground observation uses a high-precision 25-bit resolution angle measurement sensor. The angle measurement sensor has a conversion time T when measuring the angle. C At the same time, there will be a transmission delay T when the angle sensor is transmitted to the earth observation acquisition control circuit. d There is a time deviation between the moment of a certain observation point and the angle transmitted by the angle sensor, the attitude information, position, speed, time information transmitted by the satellite, etc. in the telemetry data packet packaging circuit of the acquisition circuit. The angle information transmitted by the angle sensor in the telemetry data packet is TC +T d If the above angle information is used for earth observation, the remote sensing information of earth observation will be inconsistent with the angle information of earth observation, which will lead to the accuracy of later data processing. There is also a time delay T from ADC sampling to remote sensing data packet packaging circuit. ADC , the attitude information, position, and speed information transmitted by the satellite also have a time error T sat The remote sensing data packet packaging circuit generates a 100MHz clock based on the local short-term high-stability constant temperature crystal oscillator to collect the angle information transmitted by the angle sensor and transmits the T C +T d Perform time correction, collect the on-board time synchronization pulse sent by the satellite, and collect the time information broadcast by the satellite to maintain the local clock, and use the clock to correct the time error of the observation information transmitted by the ADC acquisition circuit. ADC Correction: the error T of the attitude information, position and speed information transmitted by the satellite sat After the above errors are corrected, the angle information of different observation points of earth observation, the sampling information of different observation points, the attitude and speed of the satellite at the corresponding observation point and other information are kept consistent. The angle and position of observation are further corrected on the ground through the attitude and speed of the corresponding satellite, so as to improve the accuracy of earth observation at different observation points. After correction, the earth observation error of different observation points can be controlled within ±2 meters.

[0048] Advantages of the present invention:

[0049] The observation scans of the same observation target by different atmospheric detection payloads of commercial satellites adopt the method of multiple physical signal synchronization and software monitoring error elimination, eliminating the delay of time broadcast and time observation error caused by data reception through the CAN bus or 1553 bus of different detection payloads of traditional satellites, thereby improving the accuracy of data acquisition of the same observation target by different detection payloads.

[0050] Different channels of commercial satellite atmospheric detection payloads use multi-channel ADC synchronous sampling and sampling error elimination methods to ensure the sampling time accuracy of the same observation target between different channels, thereby reducing the ground observation error caused by the sampling time deviation of different channels and ensuring the pointing accuracy and alignment accuracy of observations from different observation channels.

[0051] While improving the accuracy of the ground scanning control motor of commercial satellite atmospheric detection payloads at different observation points on the ground, the deviation of the transmitted angle information and ADC sampling time is corrected, thereby further improving the consistency of the time information and angle information of the commercial satellite atmospheric detection payloads at different observation points on the ground, and ensuring the accuracy of observation collection at different points.

[0052] The present invention adopts a comprehensive method to reduce the observation deviation between different detection channels, different collection points and different payloads, thereby ensuring the accuracy, stability and consistency of atmospheric detection payload observation data, and ensuring the important role of commercial satellite atmospheric detection payload observation data in numerical weather forecast observation.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the accuracy of earth observation by an atmospheric detection payload, characterized in that: The following steps are involved: S1. Synchronous correction of different atmospheric detection payloads; S2. Synchronize and correct multiple channels of atmospheric detection payloads; S3, synchronously correct the observation angle, data collection time and satellite parameters of the atmospheric detection payload; In step S1, different atmospheric detection payloads are synchronously corrected, including: Define two atmospheric detection payloads, namely atmospheric detection payload A and atmospheric detection payload B; A The atmospheric detection payload uses a constant temperature crystal oscillator to generate a 100M clock to collect the on-board time pulses sent by the satellite and the time information broadcast by the satellite; Generate a 100M clock based on the local constant temperature crystal oscillator, generate a scan synchronization pulse and maintain an A atmospheric detection payload local time, and generate a scan synchronization pulse cycle based on the periodic scanning mode; After receiving the scanning synchronization pulse generated by the A atmospheric detection payload, the B atmospheric detection payload uses a constant temperature crystal oscillator to generate a 100M clock, collects the scanning synchronization pulse, and simultaneously collects the time signal broadcast on the satellite to generate the scanning start pulse of the B atmospheric detection payload. The B atmospheric detection payload starts at T delayb Then start the observation scan; At the same time, the B atmospheric detection payload will receive the scanning synchronization pulse generated by the A atmospheric detection payload and send the signal back to the A atmospheric detection payload. The A atmospheric detection payload will collect the transmission delay of the synchronization pulse sent and received by the A atmospheric detection payload, and generate the scanning start signal of the A atmospheric detection payload after time correction. The A atmospheric detection payload will start scanning at T delaya Then start the observation scan; In step S3, the satellite parameters include attitude information, position, and speed information.

2. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 1, characterized in that: In step S1, the periodic scanning method includes: Set the scanning period of the atmospheric detection payload A to M / N seconds, the scanning period of the atmospheric detection payload B to M seconds, and M seconds as the synchronization pulse period; In this way, after every N ground scans, the A atmospheric detection payload and the B atmospheric detection payload will perform a scanning synchronization.

3. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 1, characterized in that: In step S1, the ground observation accuracy of atmospheric detection payload A and atmospheric detection payload B can be improved to the order of 0.5us, and the error of atmospheric detection payload A and atmospheric detection payload B is ±2 meters.

4. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 1, characterized in that: In step S2, synchronous correction is performed between multiple channels of the atmospheric detection payload, including: The atmospheric detection payload uses a pair of earth observation antennas and simultaneously separates multi-channel detection signals; Method for synchronous sampling and sampling error elimination of multi-channel ADC of multi-channel atmospheric detection payload; The errors between multi-channel observations of atmospheric detection payloads and between multi-channel ADC sampling are eliminated by the quadratic error elimination method.

5. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 1, characterized in that: In step S2, the registration accuracy of the multi-channel observation signal of the atmospheric detection payload can be improved to ±0.001°.

6. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 4, characterized in that: In step S2, the sampling error elimination method includes: The clock phase compensation correction is performed on the sampling clocks of multiple ADCs. Multiple ADCs sample the same type of observation targets and evaluate the delay of different sampling channels. The delay information of different channels and the input of the ADC sampling clock delay circuit for different channels are sent to the atmospheric detection payload to start the observation scanning time T delaya , T delayb Correct the scan start time.

7. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 4, characterized in that: In step S2, the secondary error elimination method includes: The multi-channel ADC samples a ground observation point multiple times at a sampling rate i times higher than the normal sampling rate; According to the relationship between different sampling points and the center position of this sampling point and after multiple calculations on the calibration source and the ground observation scan value, the weight value W of each sampling is set i ; The sampling result C of each earth observation i And the corresponding weight value W i After multiplication, take the average of the operations and use the result as the result of this sampling C j At the same time, the angle and time information values ​​of the (i-1) / 2th sampling in the i sampling of this earth observation are used as the position and time mark of this earth observation.

8. The method for improving the earth observation accuracy of an atmospheric detection payload according to claim 1, characterized in that: In step S3, the observation angle of the atmospheric detection payload, the data collection time, and various satellite parameters are synchronously corrected, including: Earth observation uses an angle measurement sensor with a 25-bit resolution. The angle measurement sensor has a conversion time T when measuring the angle. C At the same time, there is a transmission delay T in the process of the angle sensor transmitting to the earth observation acquisition control circuit. d ; There is also a time delay T from ADC sampling to the remote sensing data packet packaging circuit ADC , the parameters transmitted by the satellite also have a time error T sat ; The remote sensing data packet packaging circuit generates a 100MHz clock based on the local constant temperature crystal oscillator, collects the angle information transmitted by the angle sensor, and converts the T C +T d To correct the time, collect the on-board time synchronization pulse sent by the satellite, and collect the time information broadcast by the satellite to maintain the local clock. Use this clock to collect the observation information transmitted by the ADC for time error T ADC Correction: the error T of each parameter information transmitted by the satellite sat make corrections; The observation angle and observation position are corrected on the ground using the corresponding satellite parameter information.

Images