A satellite-ground two-way ranging method based on frequency hopping TDMA communication system

Abstract

The application discloses a kind of satellite-ground two-way ranging methods based on frequency hopping TDMA communication system, comprising: (1) satellite payload sends downlink signal, ground station receives and completes pseudorange measurement.Ground station will be downlink pseudorange measurement value using uplink channel feedback to satellite, at the same time ground station needs to send TOD time adjustment amount of uplink frequency hopping synchronous to satellite;(2) ground station sends uplink signal, satellite payload receives and completes uplink pseudorange measurement, combine the TOD time adjustment amount of ground station, form uplink pseudorange calculation value, and uplink pseudorange calculation result is fed back to ground station using downlink feeder link.The satellite-ground two-way ranging method based on frequency hopping TDMA communication system is used, on the one hand, the satellite-ground two-way ranging is integrated in frequency hopping communication, the integration design of two-way ranging and frequency hopping anti-jamming communication is realized, on the other hand, ground station can carry out code phase compensation to uplink ranging value by satellite-ground frequency hopping synchronization process, the requirement of satellite equipment to ranging function is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a satellite-ground two-way ranging method based on a frequency hopping TDMA communication system and belongs to the technical field of two-way ranging. BACKGROUND

[0002] An information war puts forward higher requirements on the anti-interference capability of electronic countermeasures, and frequency hopping communication naturally has the characteristics of high interference tolerance and strong anti-interference capability, so that the frequency hopping TDMA satellite communication system is widely applied to the technical field of secure communication, but the traditional frequency hopping TDMA satellite communication system can only be used for communication and cannot be used for two-way ranging, if high-precision two-way ranging needs to be performed between communication nodes, other communication links need to be used to solve the problem, which increases the construction cost of the system and reduces the use efficiency of the frequency hopping communication system equipment.

[0003] At present, there is no system that integrates two-way ranging and anti-interference frequency hopping communication, so how to realize the integrated design of anti-interference frequency hopping communication and two-way ranging and embed the ranging process in the application requirement of the frequency hopping TDMA satellite communication system is very urgent.

[0004] In addition, the general two-way ranging system takes the local reference time as the reference time of the local ranging of the equipment, which is generally the 1PPS time, which is not completely applicable in the frequency hopping TDMA satellite communication system. SUMMARY

[0005] The application solves the technical problem of overcoming the deficiencies of the prior art and providing a satellite-ground two-way ranging method based on a frequency hopping TDMA communication system, so that the frequency hopping TDMA satellite communication can be used for two-way ranging.

[0006] The application adopts the following technical scheme:

[0007] A satellite-ground two-way ranging method based on a frequency hopping TDMA communication system comprises the following steps:

[0008] (1) a satellite payload sends a downlink signal, a ground station receives and completes downlink pseudorange measurement, and the ground station feeds back the downlink pseudorange measurement value to the satellite payload through an uplink channel, while the ground station sends a TOD time adjustment amount at the time of uplink frequency hopping synchronization to the satellite payload;

[0009] (2) the ground station sends an uplink signal, the satellite payload receives and completes uplink pseudorange measurement, combines the TOD time adjustment amount of the ground station to form an uplink pseudorange calculation value, and feeds back the uplink pseudorange calculation value to the ground station through a downlink feeder link.

[0010] Further, the ground station receives a downlink signal and completes downlink pseudorange measurement, specifically:

[0011] The satellite uses TOD time as the time base. The TOD counter increments by 1 every 50us, and 1 second equals an increment of 20,000 by the TOD counter.

[0012] The ground station uses its local time to perform ranging for the downlink ranging frame received, corresponding to the satellite's equivalent 1PPS transmission time Mod(Tod_sat, 20000) = 0. This yields the raw downlink pseudorange value, which is then interpolated to the ground station's local 1PPS time to obtain the interpolated pseudorange measurement value. The ground station performs a measurement cycle every 25 received data frames, with each received data frame having a frame period of 40ms. Tod_sat is the recovered satellite TOD time, i.e., the equivalent 1PPS time, with the integer part being a multiple of 20000 and the fractional part being measured by the ground station.

[0013] Furthermore, the downlink raw pseudorange value measured by the ground station is:

[0014]

[0015] Downlink raw pseudorange value This refers to the satellite-to-ground transmission delay of the ranging signal. The downlink raw pseudorange value is the pseudorange measurement value obtained by the ground station at the local time t_re, where t_re is the ground station time corresponding to the arrival time of the satellite ranging signal, and t_re is a non-integer second; c is the speed of light.

[0016] Furthermore, the original downlink pseudorange value is interpolated, specifically as follows:

[0017] Suppose the measurement sequence of the downlink raw pseudorange values ​​is: Using a third-order or higher Lagrange interpolation algorithm, the downlink original pseudorange value sequence is interpolated, and the corrected pseudorange measurement value at integer seconds is:

[0018] ρ down,t0 ρ down,t0+1 …ρ down,t0+n

[0019] in ρ represents the sequence of downlink raw pseudorange measurements taken by the ground station at different n+1 recovered on-board ranging signal transmission times. down,t0 ρ down,t0+1 …ρ down,t0+n This is a sequence of pseudorange measurements for consecutive n+1 integer seconds obtained by the ground station using an interpolation algorithm.

[0020] Furthermore, the ground station will adjust the TOD time during uplink frequency hopping synchronization and send the adjustment amount to the satellite payload, specifically as follows:

[0021] The ground station adjusts the local frequency hopping signal transmission time so that when the frequency hopping signal arrives at the satellite port, the TOD time carried in its communication frame is exactly the same as the satellite's local TOD time, which facilitates the on-board equipment to complete the signal demodulation of the multi-user TDMA system.

[0022] Let PR_C be the TOD time adjustment amount at the time of transmission of the uplink frequency hopping signal from the ground station. It is the difference between the TOD time carried in the uplink communication frame and the local 1PPS time of the ground station. When the TOD time carried in the communication frame is ahead of the local 1PPS time, PR_C is a positive value, and otherwise it is a negative value.

[0023] Furthermore, the ground station sends uplink signals, which the satellite payload receives and completes uplink pseudorange measurement, specifically as follows:

[0024] The uplink signal contains 25 data frames per second. The start time of the 0th frame sent by the ground station corresponds to the moment when the modulus of the transmitted signal TOD modulo 20000 equals 0. The uplink uses the 0th frame for measurement, that is, the moment when the frame count value modulo 25 is 0 and TOD modulo 20000 is 0, the ground station sends the measurement signal. The on-board equipment uses the corresponding moment when the local Mod(Tod_sat, 20000) = 0 for ranging. The moment when the satellite TOD modulo 20000 equals 0 is equivalent to 1PPS, thus obtaining the raw pseudorange measurement value PR of the uplink. sat_meas .

[0025] Furthermore, the satellite payload combines the uplink raw pseudorange measurement value PR sat_meas The actual pseudorange measurement value is calculated from the uplink frequency hopping signal TOD time adjustment amount PR_C sent by the ground station:

[0026] PR up =PR sat_meas +PR_C

[0027] Among them, PR up To recover the true uplink pseudorange measurement, PR sat_meas The PR value is the raw pseudorange measurement obtained by the onboard equipment. When the onboard frequency hopping ranging sampling time is ahead of or earlier than the uplink ranging signal recovery time, sat_meas If positive, then negative.

[0028] Furthermore, during downlink or uplink communication, the specific data frame format is as follows:

[0029] Every 25 data transmission frames correspond to one full second, and each frame lasts for 40ms. The measurement sequence is inserted once in each data frame for a duration of 100us. The communication data field is following the measurement sequence in the data frame and is used for frequency hopping communication.

[0030] The present invention also proposes a storage medium comprising a stored program, wherein, when the program is executed, the device containing the storage medium executes the satellite-to-ground two-way ranging method based on the frequency-hopping TDMA communication system.

[0031] The present invention also proposes a processor for running a program, wherein the program executes the aforementioned satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) This invention integrates the satellite-to-ground two-way ranging method into the frequency hopping TDMA communication system, and integrates anti-interference frequency hopping communication with two-way ranging into a single design, thereby improving the application efficiency of the frequency hopping TDMA system and reducing the system construction cost;

[0034] (2) The present invention has specially designed the ranging process and method. The ground station needs to adjust the TOD time of its uplink frequency hopping signal transmission time and send the adjustment amount to the satellite, which reduces the requirements of the satellite equipment for ranging function. Attached Figure Description

[0035] Figure 1 This is a flowchart of the satellite-to-ground two-way ranging process based on the frequency-hopping TDMA communication system of the present invention;

[0036] Figure 2 This is a schematic diagram of the timing relationship of the downlink ranging signal of the present invention;

[0037] Figure 3 This is a schematic diagram of the timing relationship of the uplink ranging signal of the present invention;

[0038] Figure 4 This is a schematic diagram of the uplink and downlink transmission data frame format of the present invention. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Traditional frequency-hopping TDMA satellite communication systems are only used for communication and cannot be used for two-way ranging. If high-precision two-way ranging between communication nodes is required, additional communication links are needed, increasing the system's construction cost. This invention, based on a satellite-to-ground two-way ranging method for frequency-hopping TDMA communication systems, effectively solves this problem. It integrates anti-interference frequency-hopping communication with two-way ranging, improving the application efficiency of the frequency-hopping TDMA system. Furthermore, the ranging process and method are specifically designed to suit the characteristics of frequency-hopping TDMA satellite communication systems.

[0041] In frequency-hopping TDMA satellite communication systems, the satellite payload uses the local TOD time as the time reference for ranging. The ground station also needs to adjust the TOD time of its uplink frequency-hopping signal transmission time so that when the signal arrives at the satellite port, the TOD time carried in its communication frame is exactly the same as the satellite's local TOD time. By adjusting the TOD time through the ground station, the requirements of the on-board equipment for ranging functions are reduced, which is different from the traditional ranging process and methods.

[0042] like Figure 1 As shown, this invention proposes a two-way satellite-to-ground ranging method based on a frequency-hopping TDMA communication system, which mainly includes two steps: downlink pseudorange measurement and uplink pseudorange measurement.

[0043] The specific steps are as follows:

[0044] (1) The satellite payload sends downlink signals, the ground station receives and completes downlink pseudorange measurement, and the ground station feeds back the downlink pseudorange measurement value to the satellite payload through the uplink channel. At the same time, the ground station sends the TOD time adjustment amount during uplink frequency hopping synchronization to the satellite payload.

[0045] (2) The ground station sends uplink signals, the satellite payload receives and completes uplink pseudorange measurement, and combines the TOD time adjustment of the ground station to form uplink pseudorange calculation value, and feeds back the uplink pseudorange calculation value to the ground station through the downlink feeder link.

[0046] like Figure 2 As shown, the ground station receives the downlink signal to complete the downlink pseudorange measurement, specifically as follows:

[0047] The satellite uses TOD time as its time base. The TOD counter increments by 1 every 50us, and 1 second equals an increment of 20000 from the TOD counter.

[0048] The main function of TOD is to assist in completing uplink and downlink frequency hopping synchronization and to perform satellite-to-ground frequency hopping communication. To facilitate the use of the satellite-to-ground frequency hopping system, the ground station uses the satellite equivalent 1PPS transmission time [Mod(Tod_sat, 20000) = 0] corresponding to the downlink ranging frame received, and performs ranging using the local time of the ground station. The ranging value is then interpolated to the local 1PPS time of the ground station. Every 25 received data frames constitute a measurement cycle for the ground station, and the frame period of each received data frame is 40ms.

[0049] The downlink raw pseudorange value measured by the ground station is:

[0050]

[0051] Original pseudorange value That is Figure 2 The ranging signal satellite-to-ground transmission delay is represented by the original pseudorange value, which is the pseudorange measurement value obtained by the ground station at the local time t_re. t_re is the ground station time corresponding to the arrival time of the satellite ranging signal. Generally, t_re is a non-integer second. TOD_Sat is the recovered satellite TOD time (i.e., the equivalent 1PPS time, with the integer part being an integer multiple of 20000 and the fractional part being obtained by the ground station measurement). In order to obtain the ranging value of the ground station at the local integer second, the original pseudorange value needs to be interpolated.

[0052] Let the measurement sequence of the original pseudorange be: Using a third-order or higher Lagrange interpolation algorithm, the original pseudorange sequence is interpolated, and the corrected pseudorange measurement values ​​at integer seconds are:

[0053] ρ down,t0 ρ down,t0+1 …ρ down,t0+n

[0054] in ρ represents the sequence of downlink raw pseudorange measurements taken by the ground station at different n+1 recovered on-board ranging signal transmission times. down,t0 ρ down,t0+1 …ρ down,t0+n It is a sequence of pseudorange measurements for consecutive integer seconds (n+1 seconds) obtained by ground stations through interpolation algorithms.

[0055] To achieve frequency hopping synchronization, the ground station needs to adjust the transmission time of its local frequency hopping signal so that when the signal arrives at the satellite port, the TOD time carried in its communication frame is exactly the same as the satellite's local TOD time, which facilitates the onboard equipment to complete the signal demodulation of the multi-user TDMA system.

[0056] The ground station needs to send the TOD time adjustment to the satellite to assist the satellite payload in completing the uplink pseudorange measurement. Let the TOD time adjustment at the time of transmission of the uplink frequency hopping signal by the ground station be PR_C, which is the difference between the TOD time carried in the uplink communication frame and the local 1PPS time of the ground station. When the TOD time carried in the communication frame is ahead of the local 1PPS time, PR_C is a positive value, and otherwise it is a negative value.

[0057] like Figure 3 As shown, the ground station sends uplink signals, and the satellite payload receives the frequency-hopping signals and completes the uplink pseudorange measurement, specifically as follows:

[0058] The uplink signal also consists of 25 data frames per second. The start time of the 0th frame sent by the ground station corresponds to the moment when the modulus of the transmitted signal TOD modulo 20000 equals 0. The uplink uses the 0th frame for measurement, that is, the moment when the frame count value modulo 25 is 0 and TOD modulo 20000 is 0, the ground station sends the measurement signal. The onboard equipment uses the corresponding moment [Mod(Tod_sat), 20000) = 0] for ranging. The satellite TOD modulo 20000 equaling 0 can be equivalent to 1 PPS, thus obtaining the raw pseudorange measurement value PR of the uplink. sat_meas .

[0059] Satellite payload combined with uplink raw pseudorange measurements PR sat_meas The actual pseudorange measurement value can be calculated from the uplink frequency hopping signal TOD time adjustment amount PR_C sent by the ground station:

[0060] PR up =PR sat_meas +PR_C

[0061] Among them PR up To recover the true uplink pseudorange measurement, PR sat_meas The raw pseudorange measurement value obtained by on-board equipment, i.e. Figure 3 The signal delay estimate in the PR value is calculated when the on-board frequency hopping ranging sampling time precedes or precedes the uplink ranging signal recovery time (or in other words, the on-board equipment's local TOD time precedes the TOD time carried by the uplink ranging signal). sat_meas positive ( Figure 3 (This is exactly the case), otherwise it is negative.

[0062] like Figure 4 As shown, in the satellite-to-ground two-way ranging method based on frequency-hopping TDMA communication system, the specific uplink and downlink transmission data frame formats are as follows:

[0063] Every 25 data transmission frames correspond to one full second, and each frame lasts for 40ms. The measurement sequence is inserted once in each data frame for a duration of 100us. The communication data field is following the measurement sequence in the data frame, which is mainly used for frequency hopping communication. The data frame realizes the integrated design of bidirectional ranging and frequency hopping anti-interference communication.

[0064] Compared with existing technologies, this invention integrates a two-way ranging method into the frequency-hopping TDMA communication system, combining anti-interference frequency-hopping satellite communication with two-way ranging into a single design. This improves the application efficiency of the frequency-hopping TDMA communication system and reduces system construction costs. Furthermore, it specifically designs the ranging process and method. The ground station needs to adjust the TOD time of its uplink frequency-hopping signal transmission and send the adjustment amount to the satellite, reducing the requirements of the satellite equipment on the ranging function. In summary, the method proposed in this invention can significantly improve the application efficiency of the frequency-hopping TDMA satellite communication system.

[0065] The method of this invention can meet the requirements of the integrated design of satellite-to-ground two-way ranging and TDMA frequency hopping communication in anti-interference satellite systems, reduce the requirements of on-board equipment for ranging functions, and has broad market application prospects.

[0066] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system, characterized in that... include: The satellite payload transmits downlink signals, the ground station receives and completes downlink pseudorange measurement, and the ground station feeds back the downlink pseudorange measurement value to the satellite payload using the uplink channel. At the same time, the ground station sends the TOD time adjustment amount during uplink frequency hopping synchronization to the satellite payload. The ground station transmits the TOD time adjustment amount during uplink frequency hopping synchronization to the satellite payload. Specifically, the ground station adjusts the local frequency hopping signal transmission time so that when the frequency hopping signal arrives at the satellite interface, the TOD time carried in its communication frame is exactly the same as the satellite's local TOD time, facilitating onboard equipment to complete signal demodulation for the multi-user TDMA system. Let the TOD time adjustment amount at the ground station's uplink frequency hopping signal transmission time be... This refers to the difference between the TOD time carried in the uplink communication frame and the local 1PPS time at the ground station. When the TOD time carried in the communication frame precedes the local 1PPS time... A positive value indicates a positive value, and vice versa; The ground station sends uplink signals, the satellite payload receives and completes uplink pseudorange measurement, combines the TOD time adjustment of the ground station to form uplink pseudorange calculation value, and feeds back the uplink pseudorange calculation value to the ground station through the downlink feeder link.

2. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to claim 1, characterized in that: The ground station receives the downlink signal and completes the downlink pseudorange measurement, specifically as follows: The satellite uses TOD time as the time base. The TOD counter increments by 1 every 50us, and 1 second equals an increment of 20,000 by the TOD counter. The ground station uses the local time of the ground station to perform ranging, obtaining the raw downlink pseudorange value, and interpolates the raw downlink pseudorange value to the local 1PPS time of the ground station to obtain the interpolated pseudorange measurement value. Every 25 received data frames constitute a measurement cycle for the ground station, and the frame period of each received data frame is 40ms. The recovered onboard TOD time, which is equivalent to 1 PPS time, has an integer part that is a multiple of 20,000, and a fractional part that is measured by the ground station.

3. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to claim 2, characterized in that: The downlink raw pseudorange value measured by the ground station is: Downlink raw pseudorange value This refers to the satellite-to-ground transmission delay of the ranging signal. The downlink raw pseudorange value is the local distance of the ground station. The pseudorange measurement value obtained at time 10:

00. The ground station time corresponding to the arrival time of the satellite ranging signal and For moments that are not whole seconds; It is the speed of light.

4. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to claim 3, characterized in that: Interpolate the raw downlink pseudorange values ​​as follows: Suppose the measurement sequence of the downlink raw pseudorange values ​​is: Using a third-order or higher Lagrange interpolation algorithm, the downlink original pseudorange value sequence is interpolated. The corrected pseudorange measurement values ​​at integer seconds are then: in This is a sequence of downlink raw pseudorange measurements taken by the ground station at different n+1 recovered satellite ranging signal transmission times. It is a sequence of pseudorange measurements for consecutive integer seconds (n+1 seconds) obtained by ground stations through interpolation algorithms.

5. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to claim 2, characterized in that: The ground station sends uplink signals, which are received by the satellite payload, which then completes the uplink pseudorange measurement. Specifically: One second of uplink signal contains 25 data frames. The start time of frame 0 sent by the ground station corresponds to the moment when the modulus of TOD modulo 20000 of the transmitted signal equals 0. The uplink uses frame 0 for measurement, that is, the ground station sends the measurement signal when the frame count modulo 25 is 0 and the modulus of TOD modulo 20000 is 0. The on-board equipment uses the corresponding moment when the local Mod(Tod_sat, 20000) = 0 for ranging. The moment when the satellite's TOD modulo 20000 equals 0 is equivalent to 1 PPS, thus obtaining the raw pseudorange measurement value of the uplink. .

6. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to claim 5, characterized in that: Satellite payload combined with uplink raw pseudorange measurements TOD time adjustment amount of uplink frequency hopping signal sent by ground station The calculated true pseudorange measurement value is: in, To recover the true uplink pseudorange measurement, The raw pseudorange measurement value obtained by the on-board equipment is the uplink value. When the on-board frequency hopping ranging sampling time is ahead of or earlier than the uplink ranging signal recovery time, If positive, then negative.

7. The satellite-to-ground two-way ranging method based on a frequency-hopping TDMA communication system according to any one of claims 1-6, characterized in that: During downlink or uplink communication, the specific data frame format is as follows: Every 25 data transmission frames correspond to one full second, and each frame lasts for 40ms. The measurement sequence is inserted once in each data frame for a duration of 100us. The communication data field is following the measurement sequence in the data frame and is used for frequency hopping communication.

8. A storage medium, characterized in that: The storage medium includes a stored program, wherein, when the program is executed, it controls the device where the storage medium is located to execute the satellite-to-ground two-way ranging method based on the frequency hopping TDMA communication system as described in claim 7.

9. A processor, characterized in that: The processor is used to run a program, wherein the program executes the satellite-to-ground two-way ranging method based on the frequency hopping TDMA communication system as described in claim 7.

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