CN109361480B - Automatic spread spectrum capture performance test circuit - Google Patents
Automatic spread spectrum capture performance test circuit Download PDFInfo
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- CN109361480B CN109361480B CN201811138575.4A CN201811138575A CN109361480B CN 109361480 B CN109361480 B CN 109361480B CN 201811138575 A CN201811138575 A CN 201811138575A CN 109361480 B CN109361480 B CN 109361480B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/29—Performance testing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
Abstract
The invention provides an automatic spread spectrum capture performance test circuit, and aims to provide a test circuit which is high in test efficiency and can conveniently debug and test a receiver. The invention is realized by the following technical scheme: before testing, the upper computer presets the all-1 position and the frequency testing expected precision to an all-1 testing module; the all-1 test module takes the corresponding signals of all 1 of the analog sources as reference signals, refreshes the test results each time the capture results are received, automatically counts the all-1 position exceeding, overtime and total count according to the corresponding logics of all 1 of the spread spectrum capture and all 1 of the analog sources, sends out the capture results of all 1 exceeding, all 1 overtime and all 1 total count, and reports the capture results to the upper computer for display; and the frequency testing module automatically counts the frequency exceeding and the total count in real time according to the corresponding logics of the capture frequency and the analog source frequency, and reports the frequency performance result to an upper computer for display.
Description
Technical Field
The invention relates to an automatic test circuit for spread spectrum capture performance in a spread spectrum receiver, belonging to the field of aircraft measurement and control.
Background
In the various spread spectrum modes of the spread spectrum communication system in the prior art, the most widely applied is the direct sequence spread spectrum mode (direct sequence spread spectrum, direct spread spectrum for short), for direct sequence spread spectrum communication, the acquisition of a spread spectrum code is a very critical link, the system can track and demodulate data of the spread spectrum code only after the acquisition of the spread spectrum code is completed, and the spread spectrum code acquisition circuit needs to realize the function of reducing the phase difference between a local spread spectrum code and the received spread spectrum code to be within a spread spectrum code element period. In spread spectrum communication, a pseudo-random code (also called pseudo code or PN code) is adopted at a transmitting end to spread an information code, and only when the local pseudo code and the pseudo code in a received signal are synchronized in phase, the information code can be despread at a receiving end. The PN code capturing function is to realize coarse synchronization of the pseudo code phase and provide a phase initial value (which is conventionally called as all 1 in engineering) and carrier Doppler frequency for a subsequent pseudo code tracking link. In an aircraft measurement and control communication circuit, a spread spectrum receiver can capture and track signals only by generating a local pseudo code sequence consistent with the phase of a received signal, carrying out related despreading processing on the signals and increasing the signal power to be higher than the noise power. The premise of normal demodulation of the spread spectrum receiver is that the spread spectrum is firstly despread, and the necessary condition of normal despreading is spread spectrum capture, and the correct initial phase (namely all 1) of a spread spectrum code and the carrier Doppler frequency are given in real time according to signals.
The full 1 position and frequency accuracy given by spread spectrum acquisition is affected by the information rate, the spread spectrum code rate, the number of code bits and the signal-to-noise ratio of the signal. The signal-to-noise ratio of the signal has the greatest influence on the capturing performance, and when the signal-to-noise ratio is low, the all-1 position given by capturing each time can shake back and forth near all-1 positions of the actual signal, and the Doppler frequency error can be increased. When the signal-to-noise ratio is at the acquisition threshold, even the case of acquisition failure occurs, that is, all 1 s are completely deviated from the all 1 s of the actual signal, and the doppler frequency is wrong. When the acquisition results are too biased and erroneous, the receiver will not be able to despread correctly. An important index for evaluating the spread spectrum acquisition performance is the acquisition probability, and a typical acquisition performance requires that the acquisition probability is greater than 90% under the conditions that the precision of all 1 positions is less than or equal to +/-1 chip and the frequency precision is less than or equal to +/-1 kHz. The capture performance is influenced by parameters such as signal-to-noise ratio, information rate and the like, and the capture probability index can be correctly evaluated only by a large amount of test data. Testing the capture performance is therefore a significant effort.
The spread spectrum acquisition performance mainly comprises two indexes of full 1 position precision and frequency precision. At present, in the field of aircraft measurement and control, a special hardware circuit for automatically testing the capturing performance does not exist, most of tests on the capturing performance are still manually operated, the test result is visually observed, and when the capturing frequency performance of a signal is required to be tested in frequency scanning, the signal is continuously changed in real time due to the frequency in the frequency scanning process, if the capturing frequency performance is tested by manual single sampling, the efficiency is low, and the coverage test of the whole frequency Doppler frequency deviation range is difficult to carry out.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the automatic test circuit for the spread spectrum capturing performance, which has the advantages of full automation in the test process, high test efficiency and convenience in debugging and testing the receiver, and aims to better evaluate the capturing performance in the debugging and testing processes of the spread spectrum receiver.
The above object of the present invention can be achieved by the following technical solutions: the utility model provides an automatic change spread spectrum and catch performance test circuit, includes to the host computer transmission count that exceeds standard 1 totally, 1 overtime count totally and 1 totally the total count all 1 test module, to the host computer transmission frequency count that exceeds standard and the frequency test module of frequency total count, its characterized in that: before the test starts, the all-1 test module is electrified and initialized, and the upper computer presets the all-1 position and the frequency test expected precision to the all-1 test module; after the capture starts, the all-1 test module takes the corresponding signal of the all-1 simulation source as a reference signal, the test result is refreshed immediately after receiving the capture result each time, the all-1 position exceeding, the overtime and the total count are automatically counted according to the corresponding logics of the all-1 spread spectrum capture module and the all-1 simulation source module, the all-1 exceeding count, the all-1 overtime count and the all-1 total count capture result are sent out and reported to the upper computer for display; and the frequency testing module automatically counts the frequency exceeding and the total count in real time according to the corresponding logics of the capture frequency and the analog source frequency, and reports the frequency performance result to an upper computer for display.
Compared with manual operation, the invention has the following beneficial effects:
(1) the testing process is automated. The invention transmits a full 1 test module of full 1 standard exceeding counting, full 1 overtime counting and full 1 total counting to the upper computer, and transmits a frequency test module of frequency standard exceeding counting and frequency total counting to the upper computer, and after a hardware module circuit is electrified, real-time output is started as the analog source full 1 and frequency are electrified. As long as spread spectrum capture starts to normally send out a capture result, the test module immediately refreshes the test result every time the capture result is received, and simultaneously reports the result to the upper computer for display. Compared with manual operation, the manual operation saves labor and time cost.
(2) The testing efficiency is high, and the method is simple and reliable. The invention adopts the all-1 test module and the frequency test module, and has simple structure and reliable transmission. The frequency test module automatically counts the frequency exceeding and the total count in real time according to the corresponding logic of the capture frequency and the analog source frequency, judges the frequency continuously in real time, and reports a frequency performance result to an upper computer for display, the capture frequency performance result of a signal during frequency scanning can be given in real time, and meanwhile, the test result can be automatically reported to the upper computer for display, so that the workload of the spread spectrum capture test is greatly reduced. The problem that the frequency is changed continuously in real time, coverage test is difficult to be carried out on the whole frequency Doppler frequency offset range during frequency scanning is solved, and the pain point that the efficiency is low when the frequency performance test is carried out by manual single sampling and manual test is carried out is overcome.
(3) The debugging and the testing are convenient. The invention adopts an upper computer to preset the all-1 position and the frequency test expected precision to an all-1 test module before the test begins; after the capture starts, the all-1 test module takes the corresponding signal of the all-1 simulation source as a reference signal, the test result is refreshed immediately after receiving the capture result each time, the all-1 position overproof, overtime and total count are automatically counted according to the corresponding logics of the all-1 spread spectrum capture module and the all-1 simulation source capture module, the all-1 overproof count, the all-1 overtime count and the all-1 total count capture result are sent out, and the all-1 overtime count and the overproof count can be given out simultaneously.
The invention is suitable for the working stage of debugging and testing the receiver when the spread spectrum receiver is provided with a corresponding analog source.
Drawings
The invention is further illustrated with reference to the figures and examples.
Fig. 1 is a schematic diagram of the operation principle of the automatic spread spectrum capture performance test circuit of the present invention.
FIG. 2 is a functional illustration of the all 1 test module of FIG. 1.
FIG. 3 is a flow chart of the operation of the all 1 test module of FIG. 1.
Fig. 4 is a flow chart of the operation of the frequency test module of fig. 1.
Detailed Description
See fig. 1. In the embodiments described below, an automated spread spectrum capture performance test module circuit includes a all 1 test module that transmits a all 1 superstandard count, a all 1 overtime count, and a all 1 total count to an upper computer, and a frequency test module that transmits a frequency superstandard count and a frequency total count to the upper computer. Before the test starts, the upper computer presets all 1 position and frequency test expected precision parameters to all 1 test modules; after the capture starts, the all-1 test module takes the corresponding signal of the all-1 simulation source as a reference signal, the test result is refreshed immediately after receiving the capture result each time, the all-1 position exceeding, the overtime and the total count are automatically counted according to the corresponding logics of the all-1 spread spectrum capture module and the all-1 simulation source module, the all-1 exceeding count, the all-1 overtime count and the all-1 total count capture result are sent out and reported to the upper computer for display; and the frequency testing module automatically counts the frequency exceeding and the total count in real time according to the corresponding logics of the capture frequency and the analog source frequency, and reports the frequency performance result to an upper computer for display.
The all 1 test module is internally provided with two counters, one counter is an all 1 superstandard counter, an overtime counter and a total counter which are driven by capturing all 1 arrival, the other counter is a judgment counter which is driven by a system working clock and is used for assisting in judging all 1 superstandard and overtime, and the system working clock continuously counts until a zero clearing signal comes after an initial signal. In the frequency test module, only a frequency superstandard counter and a total counter which are used as driving are refreshed at the capture frequency.
When all 1 exceeds the standard, all 1 capture exceeds the index range, but the capture does not deviate too far, the code ring of the spread spectrum receiver can enter the lock with a certain probability, and when the capture performance cannot be improved through debugging, the code ring can be adapted by adjusting the parameters of the code ring. And the overtime of all 1 indicates that the capture all 1 is far away from the position of the actual signal all 1, the code ring cannot be locked by debugging, and at the moment, the spread spectrum capture needs to be debugged again. For example, the upper computer presets the expected accuracy index of capturing all 1 positions to the all 1 test module to be less than or equal to +/-1 chip, and the over-time accuracy is less than or equal to +/-3 chips, so that the over-time accuracy is +/-3 chips.
The all-1 test module and the frequency test module respectively capture all 1 and frequency sent out by each time of spread spectrum, take analog source corresponding signals as standards, judge by taking the preset expected precision of the upper computer as a boundary, and finally report the test result to the upper computer in real time for display.
See fig. 2. All-1 test module input signals are capture all-1 and analog source all-1, the widths of the capture all-1 and the analog source all-1 are 1 chip width, the capture all-1 and the analog source all-1 should arrive at the same time under an ideal state, but are influenced by factors such as noise and the like, positive and negative offsets exist at the position of the capture all-1 every time, and the positive and negative offsets are main evaluation indexes for the performance of the capture all-1. The analog source sends all 1's of the analog source to all 1's of the test module for each code period, and the capture of all 1's will not send all 1's of the result for each code period because the capture process takes time, typically one capture all 1's of the result for every 20 code periods. So all 1's test module has captured all 1's as a trigger condition for each count. The position of the capture full 1 is advanced and lagged relative to the position of the analog source full 1, and in order to solve the problems of counting and flow when the capture full 1 lags relative to the analog source full 1, the analog source full 1 is obtained after the analog source full 1 is delayed by the number N of system working clocks corresponding to the standard exceeding precision. Such that all capture 1's must arrive before all 1's of analog sources under normal jitter conditions.
See fig. 3. The working process of the all-1 test module is as follows:
before the test is started, the all-1 test module is electrified and initialized, the upper computer sends the system clock number M corresponding to the expected accuracy of all-1 positions and the system clock number N corresponding to the standard exceeding accuracy of all-1 positions to the all-1 test module, and all counters of the all-1 test module are cleared.
In the test process, the all-1 test module firstly judges whether the capture all-1 is reached, if yes, the all-1 total count is added with 1, and meanwhile, the judgment counter is started to count from zero, otherwise, the judgment is returned to judge whether the capture all-1 is reached; if all the capture 1 arrives, continuously detecting and judging whether a counter value > N arrives earlier than all the analog sources 1, if so, judging that the result of all the capture 1 is abnormal, namely overtime, counting the overtime value +1, and simultaneously returning to judge whether all the capture 1 arrives; otherwise, continuously detecting and judging whether the counter value is less than or equal to M, if so, judging whether the capture all-1 result reaches the standard, and simultaneously returning to judge whether the capture all-1 result reaches, otherwise, judging that the capture all-1 result exceeds the standard, and judging that the over-standard count value is plus 1, and simultaneously returning to judge whether the capture all-1 result reaches.
See fig. 4. The frequency test module inputs signals of a capture frequency and an analog source frequency. The capturing frequency is influenced by factors such as noise and the like, and has deviation from the actual frequency, and the frequency error is an evaluation index of the performance of the capturing frequency. The capture frequency update period is consistent with the all-1 update period, while the analog source frequency update period is updated once in real time for 1ms, and obviously, the capture frequency update period is slower than the analog source update period.
Before the test is started, the frequency test module is electrified and initialized, the upper computer issues expected frequency precision (typical value is less than or equal to +/-1 kHz) to the frequency test module, and meanwhile, counters of the frequency test module are reset. In the test process, the frequency test module firstly judges whether the capture frequency value is refreshed, if so, a counter is started to count +1, otherwise, the frequency test module returns to judge whether the capture frequency value is refreshed again until a new frequency is detected to be captured. And after the frequency value captured by the frequency testing module is refreshed every time, judging whether the difference value between the capture frequency and the frequency of the analog source is greater than the expected frequency precision value, if so, judging that the capture frequency value exceeds the standard, adding 1 to the frequency exceeding count value, and simultaneously returning to wait for the refresh of the capture frequency value, otherwise, judging that the capture frequency value reaches the standard, and simultaneously returning to wait for the refresh of the capture frequency value.
The invention can greatly reduce the workload of testing the acquisition performance of the spread spectrum, and can be integrated in a spread spectrum receiver or be designed into a module independently.
The above detailed description of the embodiments of the present invention, and the detailed description of the embodiments of the present invention used herein, is merely intended to facilitate the understanding of the methods and apparatuses of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (9)
1. The utility model provides an automatic change spread spectrum and catch performance test circuit, includes to the host computer transmission count that exceeds standard 1 totally, 1 overtime count totally and 1 totally the total count all 1 test module, to the host computer transmission frequency count that exceeds standard and the frequency test module of frequency total count, its characterized in that: before the test starts, the all-1 test module is electrified and initialized, and the upper computer presets the all-1 position and the frequency test expected precision to the all-1 test module; after the capture starts, the all-1 test module takes a corresponding signal of the simulation source all-1 as a reference signal, the test result is immediately refreshed after receiving the all-1 capture result each time, the all-1 test module and the frequency test module respectively capture all 1 and frequency sent out by spread spectrum capture each time, the corresponding signal of the simulation source is taken as a standard, meanwhile, the judgment is carried out by taking the expected precision preset by the upper computer as a boundary, the all-1 position exceeding, the overtime and the total count are automatically counted according to the corresponding logics of the all-1 spread spectrum capture and the all-1 simulation source, the all-1 exceeding count, the all-1 overtime count and the all-1 total count capture result are sent out, and the test result is reported to the upper computer for display; and the frequency testing module automatically counts the frequency exceeding and the total count in real time according to the corresponding logics of the capture frequency and the analog source frequency, and reports the frequency performance result to an upper computer for display.
2. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: the all-1 test module is internally provided with two counters, wherein one counter is an all-1 standard exceeding counter, an overtime counter and a total counter which are driven by capturing all-1 arrival, the other counter is a judging counter which is driven by a system working clock and is used for assisting in judging all-1 standard exceeding and overtime, and the system working clock continuously counts until a zero clearing signal comes.
3. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: the frequency test module is internally provided with a frequency superstandard counter and a total counter which are driven by the capture frequency refreshing.
4. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: the input signal of the all-1 test module is capture all 1 and analog source all 1 with the width of 1 chip, the capture all 1 and the analog source all 1 arrive at the same time under an ideal state, and the all-1 test module takes the capture all 1 as a trigger condition of each counting.
5. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: in order to solve the problems of counting and flow when the capture all 1 lags relative to the capture all 1 of the analog source, the analog source is delayed by the number N of system working clocks corresponding to the standard exceeding precision of all 1 of the analog source, and the obtained analog source is delayed by all 1.
6. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: before the test is started, the all-1 test module is electrified and initialized, the upper computer sends the system clock number M corresponding to the expected accuracy of all-1 positions and the system clock number N corresponding to the standard exceeding accuracy of all-1 positions to the all-1 test module, and all counters of the all-1 test module are cleared.
7. The automated spread spectrum acquisition performance test circuit of claim 6, wherein: the all-1 test module firstly judges whether all the capture 1 is reached, if yes, the all-1 total count is added with 1, and meanwhile, the judgment counter is started to count from zero, otherwise, the judgment is returned to judge whether all the capture 1 is reached; if all the capture 1 arrives, continuously detecting and judging whether a counter value > N arrives earlier than all the analog sources 1, if so, judging that the result of all the capture 1 is abnormal, namely overtime, counting the overtime value +1, and simultaneously returning to judge whether all the capture 1 arrives; otherwise, continuously detecting and judging whether the counter value is less than or equal to M, if so, judging whether the capture all-1 result reaches the standard, and simultaneously returning to judge whether the capture all-1 result reaches, otherwise, judging that the capture all-1 result exceeds the standard, and judging that the over-standard count value is plus 1, and simultaneously returning to judge whether the capture all-1 result reaches.
8. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: the frequency test module firstly judges whether the capture frequency value is refreshed, if so, a counter is started, the total count is +1, otherwise, the frequency test module returns to judge whether the capture frequency value is refreshed again until a new frequency given by capture is detected.
9. The automated spread spectrum acquisition performance test circuit of claim 1, wherein: and after the frequency value captured by the frequency testing module is refreshed every time, judging whether the difference value between the capture frequency and the frequency of the analog source is greater than the expected frequency precision value, if so, judging that the capture frequency value exceeds the standard, adding 1 to the frequency exceeding count value, and simultaneously returning to wait for the refresh of the capture frequency value, otherwise, judging that the capture frequency value reaches the standard, and simultaneously returning to wait for the refresh of the capture frequency value.
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| US7684473B2 (en) * | 2005-06-01 | 2010-03-23 | Qualcomm Incorporated | Receiver for wireless communication network with extended range |
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