A method for testing access capacity of a multi-target satellite TT&C communication system

Abstract

The application relates to the field of spaceflight measurement and control, and discloses an access capacity testing method suitable for a multi-target satellite measurement and control communication system. A set of multi-target simulation equipment is used to construct the spectrum characteristics of different satellites in a digital domain, to construct different satellite identifiers by automatically generating data frames, and to simulate hundreds of satellites to send access application frames, so as to efficiently and conveniently test the access capacity index. The application greatly reduces the cost and time of testing the access capacity index, and the testing method is economical and efficient.

Description

TECHNICAL FIELD

[0001] The present application relates to an access capacity testing method in the field of spaceflight TT&C (Tracking, Telemetry and Command), and particularly to an access capacity testing method suitable for a multi-target satellite TT&C communication system. BACKGROUND

[0002] With the explosive growth of the number of satellites, how to efficiently perform TT&C communication for a large number of satellites has become an important problem. To solve this problem, by referring to the idea of ground mobile communication, some scholars have proposed a multi-target TT&C communication technology for satellites, which is one of the current research hotspots.

[0003] Access capacity refers to the maximum number of responses to satellite access requests per unit time. The access capacity index is used to evaluate the upper limit of the number of satellite targets and is an important index for measuring system capacity. Since the increase in the number of satellite targets is a gradual process, there is currently no effective testing method for access capacity, and a reasonable and feasible testing and evaluation method needs to be designed.

[0004] In a ground mobile communication system, a typical testing method for system capacity is to determine a traffic model according to the theoretical capacity of the communication system, set the number of call transmissions, the holding time of each call, and the interval time, and evaluate the system capacity value based on the test results. Unlike ground mobile communication systems, a satellite multi-target TT&C communication system can simultaneously process multiple target signals with different spectral characteristics and identify different satellite ID (Identity) in parallel, so the testing method of mobile communication cannot be directly copied, and the parallel processing characteristics of the system need to be considered. SUMMARY

[0005] To solve the problems in the background art, an access capacity testing method suitable for a multi-target satellite TT&C communication system is proposed, which uses a set of multi-target simulation equipment to construct the spectral characteristics of different satellites in the digital domain, generates different satellite IDs automatically, simulates the short-time parallel transmission of access application frames by hundreds of satellites, and achieves the purpose of efficient, convenient, and low-cost testing of the access capacity index.

[0006] The technical solution of the present application is as follows:

[0007] An access capacity testing method suitable for a multi-target satellite TT&C communication system, comprising the following steps:

[0008] (1) By cyclic counting, a plurality of different satellite IDs are generated each time, and corresponding data frames are generated;

[0009] (2) The plurality of data frames are modulated by a spread spectrum code, a multi-spectrum frequency offset, and amplitude adjustment in parallel, and then combined into a signal and up-converted into a radio frequency signal;

[0010] (3) setting the time interval of the two cycles and the total sending time, so that the data sending amount is not less than the product of the access capacity and the test time, and sending the radio frequency signals according to the set time;

[0011] (4) the receiving device acquires and demodulates the multiple signals according to the spectrum characteristics of the received signal, analyzes the satellite ID in the data frame, and automatically generates different response data packets according to different satellite IDs;

[0012] (5) the number of response data packets in the test time is counted to obtain the access capacity index test result.

[0013] Further, the satellite IDs of the N signals sent at the initial time in step (1) are 1-N in turn, and the satellite IDs are cyclically accumulated by N thereafter.

[0014] Further, in step (2), the symbol start phase, Doppler frequency offset and amplitude of the spread spectrum code are adjusted to the range that can be correctly identified by the receiver; wherein the ratio of the maximum signal energy to the sum of the energies of other signals is not greater than the total interference ratio requirement, and the symbol start phase and the Doppler frequency offset are greater than the target resolution requirement.

[0015] Further, in step (3), the total sending time is:

[0016] M=floor{NT / (T f +T d )}>CT

[0017] Wherein, M represents the total sending time, floor{·} represents the down rounding, C represents the access capacity index requirement, T represents the test time, T f represents the duration of each frame, and T d represents the time interval between the two frames.

[0018] Further, the access capacity index test result of step (5) is:

[0019]

[0020] Wherein, is the number of response data packets actually tested and counted in the time T, is the access capacity calculated according to and the test time;

[0021] When , it is judged that the test is qualified.

[0022] Compared with the background art, the present application has the following advantages:

[0023] (i) The present application constructs the spectrum characteristics of different satellites in the digital domain, which is conducive to the testing of the multi-target processing capacity of system access capacity.

[0024] (ii) The present application constructs different satellite identities by automatically generating data frames, which is conducive to the statistics of the number of data packets responding to satellite access requests.

[0025] (iii) The present application simulates hundreds of satellites sending access requests in a short time, which is conducive to the rapid and convenient testing of access capacity indicators, greatly reducing the testing complexity and cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the present application is shown.

[0027] Figure 2 The principle diagram of the present application for generating satellite ID by loop counting is shown. DETAILED DESCRIPTION

[0028] The present application will be further described in combination with specific implementation steps:

[0029] A kind of access capacity test method suitable for multi-target satellite TT&C communication system, refer to Figure 1 , specific steps include:

[0030] (1) by loop counting, generate a plurality of different satellite IDs every time counting, and generate corresponding data frames;

[0031] As shown in Figure 2 , the satellite ID of N-way signal transmission at the initial moment is 1~N in turn, and thereafter ID is accumulated by loop counting by the number of ways N, the satellite ID (k, n) of the nth branch transmitted for the k (k=1, …, M) time is expressed as:

[0032]

[0033] In the formula, M is the total number of transmissions, and the maximum value of N is limited by the maximum parallel capture capability of the receiving equipment.

[0034] (2) the N data frames are parallelly modulated by spread spectrum code, multi-spectrum frequency offset and amplitude adjustment, then merged into a signal, and up-converted into a radio frequency signal;

[0035] Wherein, the sum of N-way digital signals, and the expression after normalization is:

[0036]

[0037] In the formula, t represents the time, n represents the nth (n=1, …, N) digital branch, d n (t) represents data, An represents the amplitude, c(t) represents the spread spectrum code modulation (the spread spectrum code of all targets is the same), T cn represents the start time of the spread spectrum code symbol, f dn represents the Doppler frequency offset, θ n represents the initial phase of the carrier.

[0038] When parallel processing, the symbol start phase of the spread spectrum code, the Doppler frequency offset and the amplitude are respectively adjusted to the range that can be correctly identified by the receiver; wherein the ratio of the maximum signal energy to the total sum of the energies of other signals is not greater than the total interference to signal ratio requirement, that is:

[0039]

[0040] wherein, without loss of generality, represents the maximum signal energy, represents the total sum of the energies of other signals, and ISR represents the total interference to signal ratio requirement.

[0041] and the symbol start phase and the Doppler frequency offset are greater than the target resolution requirement.

[0042] (3) Set the time interval of the two cycles before and after and the total transmission time, so that the data transmission amount is not less than the product of the access capacity and the test time, and transmit the radio frequency signal according to the set time;

[0043] The total transmission times M can be calculated by the formula:

[0044] M = floor{NT / (T f + T d )} > CT

[0045] Wherein, M represents the total transmission times, floor{·} represents the down rounding, C represents the access capacity index requirement, T represents the test time, T f represents the duration of each frame, T d represents the time interval between the two frames.

[0046] (4) The receiving device acquires and demodulates the multiple signals from the received signal according to the spectral characteristics, parses the satellite ID in the data frame, and automatically generates different response data packets according to different satellite IDs.

[0047] (5) The number of response data packets in the test time is counted to obtain the access capacity index test result; wherein the access capacity index test result is:

[0048]

[0049] Wherein, is the number of response data packets actually tested and counted in the time T, is calculated according to and the test time;

[0050] When , it is judged that the test is qualified.

[0051] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, and they should all be covered in the scope of the claims of the present application.

Claims

1. A method for testing the access capacity of a multi-target satellite telemetry, tracking, and command (TT&C) communication system, characterized in that, Includes the following steps: (1) By cyclic counting, multiple different satellite IDs are generated each time a count is made, and corresponding data frames are generated; (2) Each data frame is modulated with spreading code, Doppler frequency offset and amplitude adjustment, and then multiple data frames are merged into one signal and upconverted to radio frequency signal; (3) Set the time interval between the two consecutive counts and the total transmission time so that the amount of data transmitted is not less than the product of the access capacity and the test time, and send the radio frequency signal according to the set time. (4) The receiving device captures and demodulates multiple signals from the received signal based on the spectrum characteristics, parses the satellite ID in the data frame, and automatically generates different response data packets based on different satellite IDs; (5) Count the number of response data packets within the test time to obtain the test results of the access capacity index; In step (2), the symbol start phase, Doppler frequency offset and amplitude of the spreading code are adjusted to the range that the receiver can correctly identify; wherein, the ratio of the maximum amplitude signal energy to the sum of the energy of other signals is not greater than the total interference-to-signal ratio requirement, and the symbol start phase and Doppler frequency offset are greater than the target resolution requirement.

2. The access capacity testing method for a multi-target satellite telemetry, tracking, and command communication system according to claim 1, characterized in that, In step (1), the satellite IDs of the N signals sent at the initial moment are 1 to N in sequence, and thereafter the satellite IDs are accumulated by N in a loop according to the number of channels.

3. The access capacity testing method for a multi-target satellite telemetry, tracking, and command communication system according to claim 1, characterized in that, The total number of times the message is sent in step (3) is: M=floor{NT / (T f +T d )}>CT In the formula, M represents the total number of transmissions, floor{·} represents rounding down, C represents the access capacity requirement, and T represents the test time. f T represents the duration of each frame. d This indicates the time interval between two consecutive frames.

4. The access capacity testing method for a multi-target satellite telemetry, tracking, and command communication system according to claim 1, characterized in that, The test results for the access capacity index in step (5) are as follows: In the formula, This represents the number of response data packets obtained from actual testing statistics within time T. It is based on The access capacity is calculated based on the test time; when When the time is right, the test is considered to be qualified.

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