Frequency scale test expansion card of frequency scale comparator and corresponding test method

Abstract

The invention belongs to the technical field of electronic signal measurement, and particularly discloses a frequency scale test expansion card of a frequency scale comparator and a corresponding test method. The frequency scale test expansion card comprises an instruction control module, a signal processing module, a communication interface module and a signal interface module. According to the test method provided by the invention, on the basis of the instruction control module and the signal processing module, combined with necessary process control and data processing, multi-path input frequency signals are selectively output, then the output frequency signals are sent to an external instrument frequency scale comparator for testing, and test results are regularly obtained. And after data processing, a test result is packaged and reported. According to the invention, the cost can be reduced, the efficiency can be improved, the use of a frequency scale comparator can be reduced by times, the frequency test efficiency in the same time range can be improved, and different requirements of small-batch trial production and large-batch mass production can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic signal measurement, and in particular relates to a frequency standard test expansion card of a frequency standard comparator and a corresponding test method. Background Art

[0002] In the defense industry, astronomy, physics, communications, aerospace, instrumentation and other industries, after the products that can generate frequency signals are manufactured, they often need to be tested for their output frequency drift rate characteristics due to the inherent deviation of the physical system inside the product and the different timekeeping performance caused by various application environments, in order to screen out qualified timekeeping products. The frequency drift rate is calculated from the relative average frequency deviation between the output frequency signal of the tested product and the reference standard frequency signal, and the test instrument used to test the relative average frequency deviation is called a frequency standard comparator.

[0003] Frequency standard comparators can be divided into single-channel frequency standard comparators and multi-channel frequency standard comparators. At present, the domestic frequency standard comparators mainly include the XHTF3596K series frequency standard comparators of Chengdu Tianao Electronics Co., Ltd., the SYN5609 frequency standard comparators of Xi'an Synchronous Electronics, the P07D-2 series frequency standard comparators of Shijiazhuang Shuying Instruments, and the TD-45 series frequency standard comparators of Beijing Tiandou Technology Co., Ltd., while the foreign ones mainly include the 3120A series frequency standard comparators of Microsemi in the United States, the VCH-315 series frequency standard comparators of VREMYA-CH in Russia, and the A7 series frequency standard comparators of Quartzlock in the United Kingdom.

[0004] At present, a single-channel frequency standard comparator can only test one product at a time; a multi-channel frequency standard comparator can test multiple products at the same time. However, due to factors such as portability, signal interference, heat dissipation, test accuracy, manufacturing difficulty, and cost, it is divided into 1-channel, 3-channel, 8-channel, 10-channel, and 16-channel inputs according to the number of channels being tested simultaneously. Generally, the 10-channel input model (such as the XHTF3596K series frequency standard comparator of Chengdu Tianao Electronics Co., Ltd.) is the most commonly used. Whether a single-channel frequency standard comparator or a multi-channel frequency standard comparator is used, in the process of mass product testing, many test stations, frequency standard comparators, and corresponding supporting host computer software need to be prepared, which will occupy a large amount of product R&D and testing costs.

[0005] In addition, during the test of the frequency drift rate using the frequency standard comparator, due to the frequency drift rate characteristics, calculation accuracy and confidence requirements, the collected frequency deviation data should be accumulated for a natural time of more than 7 days. At the same time, according to the frequency drift rate calculation characteristics and the principle that data sampling should be as accurate as possible and the amount of data should not be too much, under the premise of uninterrupted frequency signal input, the data sampling time interval of the frequency standard comparator is generally set to 100 seconds (under the same test duration conditions, the smaller the sampling interval, the more data), and then the upper computer software processes and calculates the data to obtain the frequency drift rate. At this time, the frequency standard comparator has a certain degree of hardware resource idleness (the frequency standard comparator test data transmission takes less than 1 second, so most of the time it is in a waiting state). In the process of mass product testing, the more frequency standard comparators are used, the more accumulated idle resources there are, which does not conform to the company's operating principles of reducing costs and increasing efficiency, and reducing carbon emissions. Summary of the invention

[0006] The purpose of the present invention is to provide a frequency standard test expansion card for a frequency standard comparator, which can simultaneously access the frequency signals of multiple products under test, output only the selected frequency signals at the same time, and send them to the frequency standard comparator for frequency standard comparison testing. By reducing the data sampling time interval of the frequency standard comparator, it is ensured that within the same test time range, the number of frequency standard comparators used is reduced exponentially without affecting the final test results. It has the characteristics of low cost and high reliability.

[0007] Another object of the present invention is to provide a testing method, which is implemented by using the frequency standard test expansion card of the above-mentioned frequency standard comparator, which can realize automatic control of large-scale tests, solve the problems of repetitive work and low efficiency of personnel, and further improve the efficiency of automated testing.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A frequency standard test expansion card for a frequency standard comparator, comprising a command control module, a signal processing module, a communication interface module and a signal interface module; The signal processing module includes N signal processing submodules, and the signal processing submodule includes a subcontroller, a frequency conversion circuit, and a shunt switch module; N≥2; the shunt switch module includes a multiple-choice shunt switch; The frequency conversion signal output terminal and the channel switching signal output terminal of the command control module are connected to the input terminals of each sub-controller of the signal processing module. The command control module sends instructions to each sub-controller, and the sub-controller further sends instructions to the corresponding frequency conversion circuit and shunt switch module. The frequency conversion circuit and shunt switch module execute the frequency conversion command and switch switching command according to the received instructions. The input end of the signal processing module receives an external signal through the signal receiving end of the signal interface module, and is connected to the signal input end of the external frequency standard comparator through the signal output end of the signal interface module; the frequency conversion circuit performs frequency conversion on the signal received from the signal receiving end of the signal interface module; the branch switch selects one of the signals after the frequency conversion, and sends it to the external frequency standard comparator through the signal output end of the signal interface module; The command control module is connected to the external frequency standard comparator and the host computer through the communication interface module; the command control module obtains the test result from the frequency standard comparator through the communication interface module, encapsulates the test result data packet and sends the encapsulated test result data packet to the host computer through the communication interface module.

[0009] As a limitation, N=10; the branch switch adopts a ten-to-one branch switch.

[0010] As a second limitation, the command control module also includes a communication signal light for indicating whether the connection with the frequency standard comparator is successful.

[0011] As a further limitation of the signal processing module, the signal processing module also includes ten instruction signal lights for indicating the signal selection numbers of all branch switches.

[0012] A test method is implemented by using the frequency standard test expansion card of the above-mentioned frequency standard comparator, and the test method comprises the following steps performed in sequence: S1, power on, initialization; S2, self-check of each module and hardware; S3, start the signal processing module; S4, start the command control module; S5. Setting the frequency conversion circuit in the signal processing module through the instruction control module to set the output frequency of the frequency conversion circuit to a preset value; S6, setting the branch switch in the signal processing module through the command control module; S7, perform the following two operations a. Each branch switch sends the selected frequency signal to the external frequency standard comparator through the signal output terminal of the signal interface module at the set time interval until the entire test process is completed; b. Data processing b1. The command control module sends the query command of the test result to the frequency standard comparator through the communication interface module at regular intervals. b2. Determine whether to switch. If yes, proceed to step S6. Otherwise, loop through step b until the entire test process is completed. In the above process, after the instruction control module sends the query instruction of the test result to the frequency standard comparator through the communication interface module for the first time, during the process of executing step S6 or S7, if the instruction control module receives the test result returned by the frequency standard comparator through the communication interface module, the interrupt program P is entered. Interrupt program P and proceed in the following order: P1, the command control module performs signal jump processing on the received test results, and then encapsulates them into a test result data packet; P2. Send the test result data packet to the host computer through the communication interface module, and then return to the step before the interruption to continue execution.

[0013] As a limitation, after completing step S4 and before executing step S5, the instruction control module executes the following steps: T41, check whether the communication between the instruction control module and the frequency standard comparator is normal, if yes, set the sampling time interval of the frequency standard comparator, and then execute step T42, otherwise directly execute step T42; T42, set the communication signal light to the corresponding state, and then go to step S5.

[0014] As a further limitation, step S6 includes the following steps performed in sequence: S61, set the switching order number of the branch switch to order; order∈[1,10], and the initial value is 1; S62, set the branch switch number to no, no∈[1,10], and the initial value to 1; S63, setting the branch switch numbered no to switch to the order road; S64, determine whether the branch switch number no is equal to 10, if yes, execute step S65, otherwise, increment the branch switch number no by 1 and return to step S63; S65, setting the initialization data processing start time and data processing end time; S66, determine whether the current time distance data processing start time reaches the set value A, if yes, execute step S67, otherwise, execute step S66 again; S67. Go to step S7.

[0015] As a further limitation of step S7, in step S7, before the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S71 is first executed, and after the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S72 is executed; S71, determine whether the time from the current time to the end time of data processing reaches the set value A, if yes, send a query instruction of the test result to the frequency standard comparator through the communication interface module, otherwise continue to execute step S71; S72, updating the data processing end time to the current time; The method for determining whether the switch needs to be switched in step S7 is performed in the following order: S73, determine whether the current time distance data processing start time reaches the set value B, if yes, execute step S74, otherwise re-enter step S7; S74, determine whether the order of the branch switch is equal to 10, if so, assign order to 1 and return to step S61, otherwise, order is incremented by 1 and return to step S61; Among them, B>A.

[0016] As a further limitation on the test result data packet, the data in the test result data packet includes the branch switch number no, the branch switch switching sequence number order, and the test result.

[0017] As a further limitation of step S61, in step S61, after setting the branch switch switching sequence number to order, a corresponding instruction signal light is set.

[0018] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art: (1) The present invention can simultaneously access the frequency signals of multiple products under test, output only the selected frequency signals at the same time, and connect the output frequency signals to the frequency standard comparator for frequency standard comparison test. By reducing the data sampling time interval of the frequency standard comparator, it is ensured that within the same test time range, the number of frequency standard comparators used is reduced exponentially without affecting the final test results. It has the characteristics of low cost and high reliability. (2) The present invention uses a frequency conversion circuit and a 10-to-1 branch switch as the basis, combined with data processing, to select and output 10 frequency signals from 100 input frequency signals, use an external instrument frequency standard comparator to perform frequency deviation test on the frequency signal, and obtain the test results regularly. After signal jump processing and data packet encapsulation and reporting, the test efficiency within the same time range is improved; (3) The frequency test expansion card provided by the present invention is easy to use and operate, does not require additional configuration, and runs fully automatically, thereby reducing the overall hardware investment cost; the introduction of an automated switching switch and a method for obtaining test results realizes automated control of large-scale tests, solves the problems of repeated labor and low efficiency of personnel, and further improves the efficiency of automated testing; (4) The present invention can meet the different needs of small-batch trial production and large-scale mass production; (5) Since the 10-to-1 branch switch may cause a sudden jump in the frequency signal (less than 3 seconds) when performing signal switching, the present invention calls the data processing module branch program to perform signal sudden jump processing when receiving the data returned by the frequency standard comparator after the switch switching is completed, so as to avoid reporting abnormal data packets and thus affecting the final test results; (6) The present invention is provided with ten instruction signal lights for indicating the signal selection numbers of all branch switches, which can intuitively display the selected signal output sequence numbers of all current branch switches, which is helpful for the staff to understand the working status of the frequency standard test expansion card, eliminate faults in time, and improve the detection efficiency; (7) The present invention includes a communication signal light for indicating whether the connection with the frequency standard comparator is successful, which can intuitively display the connection status between the current frequency standard test expansion card and the frequency standard comparator, which is helpful for the staff to understand the software and hardware status in time and improves the usability of the device.

[0019] The invention belongs to the technical field of electronic signal measurement and can improve the efficiency of automatic testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0021] In the attached picture: Figure 1 This is a hardware principle block diagram of Embodiment 1 of the present invention; Figure 2 is an overall flow chart of Embodiment 2 of the present invention; Figure 3 This is a workflow diagram of some steps of Example 2 of the present invention; Figure 4 It is a comparison diagram of the signal timing diagrams received by the time-frequency standard comparator using Example 2 and not using Example 2. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] Embodiment 1 A frequency standard test expansion card for a frequency standard comparator like Figure 1 As shown, this embodiment includes a command control module, a signal processing module, a communication interface module and a signal interface module.

[0024] The signal processing module includes 10 signal processing submodules, which include a subcontroller, a frequency conversion circuit, and a shunt switch module; the shunt switch module includes a 10-choose-1 shunt switch, and the signal processing module also includes ten LED command signal lights for indicating the selection numbers of all shunt switch signals. The command control module includes an LED communication signal light for indicating whether the connection with the frequency standard comparator is successful.

[0025] The frequency conversion signal output terminal and channel switching signal output terminal of the instruction control module are connected to the input terminals of each sub-controller of the signal processing module. The instruction control module sends instructions to each sub-controller, and the sub-controller further sends instructions to the corresponding frequency conversion circuit and shunt switch module. The frequency conversion circuit executes the frequency conversion command according to the received instruction, and the shunt switch module executes the switch switching command according to the received instruction and sets the corresponding LED instruction signal light status.

[0026] The input end of the frequency conversion circuit in the signal processing module is connected to the signal input end of the signal interface module. The signal output end after the shunt switch is selected is the signal output end of the signal interface module, and the signal output end of the signal interface module is connected to the signal input end of the external frequency standard comparator; the multi-channel frequency signals to be measured pass through the signal interface input end and reach the frequency conversion circuit. After the frequency signals are converted into signals of specified frequency points, they reach the shunt switch, and then are selected and output by the shunt switch, and finally are sent to the external frequency standard comparator through the signal output end of the signal interface module.

[0027] The command control module is also connected to the external frequency standard comparator and the host computer through the communication interface module for communication; the command control module obtains the test results from the frequency standard comparator through the communication interface module, and after performing signal jump processing, encapsulates it into a test result data packet, and finally sends the result data packet to the host computer through the communication interface module.

[0028] In this embodiment, the communication interface module uses two RS232 communication interfaces to communicate with the external frequency standard comparator and the host computer respectively; the signal interface module has a 100-way SMA interface signal input terminal and a 10-way SMA interface signal output terminal; the core circuit of the instruction control module uses the commercially available ARM microcontroller STM32F407; the signal processing module uses a frequency conversion chip with model Si5351 to construct a frequency conversion circuit, uses a chip with model xc7s25 to construct a 10-to-1 branch switch, and uses a chip with model SGM48751 to construct a sub-controller.

[0029] In this embodiment, the frequency conversion circuit is built on the basis of a chip with a frequency conversion function, which can convert the measured frequency signals of different frequency points into frequency signals of the frequency points supported by the external frequency standard comparator. The branch switch is composed of ten ten-choose-one branch switches, each branch switch selects the frequency signals of 10 inputs, outputs only one, and the switch switching function is performed by the sub-controller. The switch sequence numbers of the 10 control branch switches at the same time point are all the same. The signal processing module also includes ten LED command signal lights that correspond one to one with the switch sequence numbers of the branch switches.

[0030] The communication interface module is used to communicate with the frequency standard comparator and the host computer respectively, perform necessary data interaction, and thus obtain and report the final test results. The signal interface module is used for the transmission of the measured frequency signal.

[0031] The instruction control module is the core control module of this embodiment, which stores relevant instructions for communicating with the frequency mark comparator, the host computer and internal program control, including setting the test sampling time of the frequency mark comparator, obtaining the frequency difference test result of the frequency mark comparator, returning the current switch sequence number and the corresponding frequency difference test result, executing switch switching of the control branch switch, controlling the frequency conversion circuit to execute frequency conversion, and controlling the status of the corresponding LED instruction signal light; at the same time, it serves as the operation and control core of the frequency mark test expansion card.

[0032] The frequency test expansion card provided in this embodiment is simple to use and operate, does not require additional configuration, and runs fully automatically, thereby reducing the overall hardware investment cost; the introduction of an automated switching switch and a method for obtaining test results realizes automated control of large-scale tests, solves the problems of repetitive work and low efficiency of personnel, and further improves the efficiency of automated testing.

[0033] Example 2 A test method This embodiment is implemented by using embodiment 1. Figure 2 As shown, this embodiment includes the following steps performed in sequence: S1, power on, initialization; S2, self-check of each module and hardware; S3, start the signal processing module; S4, start the command control module; S5, setting the frequency conversion circuit in the signal processing module through the instruction control module, setting the output frequency of the frequency conversion circuit to a preset value, which is positively correlated with the input frequency value of the frequency standard comparator; S6, setting the branch switch in the signal processing module through the command control module; S7, perform the following two operations; a. Each branch switch sends the selected frequency signal to the external frequency standard comparator through the signal output terminal of the signal interface module at the set time interval until the entire test process is completed; b. Data processing b1. The command control module sends the query command of the test result to the frequency standard comparator through the communication interface module at regular intervals. b2. Determine whether to switch. If yes, proceed to step S6. Otherwise, loop through step b until the entire test process is completed. In the above process, after the instruction control module sends the query instruction of the test result to the frequency standard comparator through the communication interface module for the first time, during the process of executing step S6 or S7, if the instruction control module receives the test result returned by the frequency standard comparator through the communication interface module, the interrupt program P is entered. Interrupt program P and proceed in the following order: P1, the command control module performs signal jump processing on the received test results, and then encapsulates them into a test result data packet; P2. Send the test result data packet to the host computer through the communication interface module, and then return to the step before the interruption to continue execution.

[0034] like Figure 3 As shown, after completing step S4 and before executing step S5, the instruction control module executes the following steps: T41, check whether the communication between the instruction control module and the frequency standard comparator is normal, if yes, set the sampling time interval of the frequency standard comparator, and then execute step T42, otherwise directly execute step T42; T42, set the communication signal light to the corresponding state, and then go to step S5.

[0035] As a further limitation, step S6 includes the following steps performed in sequence: S61, set the switching order number of the branch switch to order, and set the corresponding signal indicator light; order∈[1,10], and the initial value is 1; S62, set the branch switch number to no, no∈[1,10], and the initial value to 1; S63, setting the branch switch numbered no to switch to the order road; S64. Determine whether the branch switch number no is equal to 10. If so, execute step S65; otherwise, increment the branch switch number no by 1 and return to step S63.

[0036] S65, setting the initialization data processing start time start_time and the data processing end time end_time; S66, determine whether the current time distance data processing start time start_time reaches the set value A, if yes, execute step S67, otherwise, execute step S66 again; S67. Go to step S7.

[0037] like Figure 3 As shown, in step S7, before the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S71 is first executed, and after the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S72 is executed; S71, determine whether the duration from the current time to the end time of data processing end_time reaches the set value A, if so, send a query instruction of the test result to the frequency standard comparator through the communication interface module, otherwise continue to execute step S71; S72. Update the data processing end time end_time to the current time.

[0038] The method for determining whether the switch needs to be switched in step S7 is performed in the following order: S73, determine whether the current time distance data processing start time start_time reaches the set value B, if yes, execute step S74, otherwise re-enter step S7; S74, determine whether the order of the branch switch is equal to 10, if so, assign order to 1 and return to step S61, otherwise, order is incremented by 1 and return to step S61; Among them, B>A.

[0039] In this embodiment, the data in the test result data packet includes the branch switch number no, the branch switch switching sequence number order, and the test result.

[0040] In this embodiment, A=1 second, B=10 seconds.

[0041] The test method of this embodiment is compared with the prior art, and the test parameters and results obtained are shown in Table 1 below: The daily drift rate calculations in Table 1 are all calculated and captured by the Stable32 tool software commonly used in the time-frequency field. Through test verification results, this embodiment is applicable to products with a daily drift rate index ≥ 1E-12.

[0042] During the test, the six tested products all output two 10MHz frequency signals at the same time. The first frequency signal of each tested product is sent directly to the frequency standard comparator A without passing through the frequency standard test expansion card, and connected to interfaces 1 to 6 respectively; the second frequency signal of each tested product uses the frequency standard test expansion card, and is sent to the frequency standard comparator B after passing through the frequency standard test expansion card, and is only connected to interface 1. At the same time, the corresponding host computer software is started for data collection. The test lasts about 9 days.

[0043] Combined with Table 1 Figure 4 From the test results, it can be seen that when conducting daily drift rate index test on products with daily drift rate index ≥ 1E-12, using the frequency standard test expansion card provided in Example 1 in combination with the test method of this embodiment can greatly save the hardware expenditure of the frequency standard comparator without affecting the final index.

[0044] It can be seen that the present embodiment realizes the conversion of 100 input frequency signals into 10 output frequency signals, which are sent to the frequency standard comparator for testing, and a connection is established with the frequency standard comparator through the serial port to obtain the test results and report them; after a certain period of time, another 10 signals are automatically output, the results are obtained and reported, and this cycle is repeated continuously. Ultimately, within the same test cycle, the result of testing only 10 signals can be increased to 100 signals, thereby doubling the test efficiency.

[0045] This example uses a command control module to program all frequency conversion circuits, with the aim of converting input signals of different frequencies into frequency signals (generally 10 MHz) that can be used by the frequency standard comparator, thereby further expanding the scope of application of the frequency standard test expansion card of Example 1.

[0046] In this embodiment, the command control module performs program automation control on each control branch switch. After the power-on initialization is completed, all control branch switches are switched to the 1st route by default. After running for a specified time (default: 10 seconds), all switches are switched to the 2nd route, and so on. After the 10th route runs for a specified time, it is switched back to the 1st route. Because the frequency signal will jump (less than 3 seconds) when the switch is switched, the signal jump processing is performed in the data processing branch program of the command control module to ensure that the final test result is not affected.

[0047] This embodiment uses a mature, reliable and stable ARM single-chip microcomputer, a frequency conversion chip, a shunt switch, a signal interface and a communication interface as the basis, combined with necessary operation control and data processing, to realize the cyclic selection and output of 10 frequency signals among the 100 input frequency signals, and uses an external instrument frequency standard comparator to perform frequency deviation test on the frequency signal, and obtains the test results regularly, and reports the results after secondary data packaging. When the frequency standard test expansion card of the embodiment is not used, 100 frequency signal tests for one week require 10 frequency standard comparators. After using the frequency standard test expansion card of embodiment 1 and combining it with the method provided in this embodiment, 100 frequency signal tests for one week only require 1 frequency standard comparator, which greatly reduces hardware expenditure and improves the test efficiency within the same time range.

Claims

1. A frequency standard test expansion card for a frequency standard comparator, characterized in that: It includes a command control module, a signal processing module, a communication interface module and a signal interface module; The signal processing module includes N signal processing submodules, and the signal processing submodule includes a subcontroller, a frequency conversion circuit, and a shunt switch module; N≥2; the shunt switch module includes a multiple-choice shunt switch; The frequency conversion signal output terminal and the channel switching signal output terminal of the command control module are connected to the input terminals of each sub-controller of the signal processing module. The command control module sends instructions to each sub-controller, and the sub-controller further sends instructions to the corresponding frequency conversion circuit and shunt switch module. The frequency conversion circuit and shunt switch module execute the frequency conversion command and switch switching command according to the received instructions. The input end of the signal processing module receives an external signal through the signal receiving end of the signal interface module, and is connected to the signal input end of the external frequency standard comparator through the signal output end of the signal interface module; the frequency conversion circuit performs frequency conversion on the signal received from the signal receiving end of the signal interface module; the branch switch selects one of the signals after the frequency conversion, and sends it to the external frequency standard comparator through the signal output end of the signal interface module; The command control module is connected to the external frequency standard comparator and the host computer through the communication interface module; the command control module obtains the test result from the frequency standard comparator through the communication interface module, encapsulates the test result data packet and sends the encapsulated test result data packet to the host computer through the communication interface module.

2. The frequency standard test expansion card of the frequency standard comparator according to claim 1, characterized in that: N=10; the branch switch adopts a ten-to-one branch switch.

3. The frequency standard test expansion card of the frequency standard comparator according to claim 1, characterized in that: The command control module also includes a communication signal light for indicating whether the connection with the frequency standard comparator is successful.

4. A frequency standard test expansion card for a frequency standard comparator according to claim 2, characterized in that: The signal processing module also includes ten instruction signal lights for indicating the selection numbers of all branch switch signals.

5. A test method, implemented by using a frequency standard test expansion card of a frequency standard comparator according to any one of claims 1 to 4, characterized in that: The test method comprises the following steps which are performed in sequence: S1, power on, initialization; S2, self-check of each module and hardware; S3, start the signal processing module; S4, start the command control module; S5. Setting the frequency conversion circuit in the signal processing module through the instruction control module to set the output frequency of the frequency conversion circuit to a preset value; S6, setting the branch switch in the signal processing module through the command control module; S7, perform the following two operations a. Each branch switch sends the selected frequency signal to the external frequency standard comparator through the signal output terminal of the signal interface module at the set time interval until the entire test process is completed; b. Data processing b1. The command control module sends the query command of the test result to the frequency standard comparator through the communication interface module at regular intervals. b2. Determine whether to switch. If yes, proceed to step S6. Otherwise, loop through step b until the entire test process is completed. In the above process, after the instruction control module sends the query instruction of the test result to the frequency standard comparator through the communication interface module for the first time, during the process of executing step S6 or S7, if the instruction control module receives the test result returned by the frequency standard comparator through the communication interface module, the interrupt program P is entered. Interrupt program P and proceed in the following order: P1, the command control module performs signal jump processing on the received test results, and then encapsulates them into a test result data packet; P2. Send the test result data packet to the host computer through the communication interface module, and then return to the step before the interruption to continue execution.

6. The test method according to claim 5, wherein the command control module further comprises a communication signal light for indicating whether the connection with the frequency standard comparator is successful, characterized in that: After completing step S4 and before executing step S5, the instruction control module executes the following steps: T41, check whether the communication between the instruction control module and the frequency standard comparator is normal, if yes, set the sampling time interval of the frequency standard comparator, and then execute step T42, otherwise directly execute step T42; T42, set the communication signal light to the corresponding state, and then go to step S5.

7. The test method according to claim 5, wherein the signal processing module comprises ten signal processing submodules; the branch switch adopts a ten-to-one branch switch, characterized in that: The step S6 comprises the following steps which are performed in sequence: S61, set the switching order number of the branch switch to order; order∈[1,10], and the initial value is 1; S62, set the branch switch number to no, no∈[1,10], and the initial value to 1; S63, setting the branch switch numbered no to switch to the order road; S64, determine whether the branch switch number no is equal to 10, if yes, execute step S65, otherwise, increment the branch switch number no by 1 and return to step S63; S65, setting the initialization data processing start time and data processing end time; S66, determine whether the current time distance data processing start time reaches the set value A, if yes, execute step S67, otherwise, execute step S66 again; S67. Go to step S7.

8. The testing method according to claim 7, characterized in that: In step S7, before the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S71 is first executed, and after the instruction control module sends a query instruction of the test result to the frequency standard comparator through the communication interface module each time, step S72 is executed; S71, determine whether the time from the current time to the end time of data processing reaches the set value A, if yes, send a query instruction of the test result to the frequency standard comparator through the communication interface module, otherwise continue to execute step S71; S72, updating the data processing end time to the current time; The method for determining whether the switch needs to be switched in step S7 is performed in the following order: S73, determine whether the current time distance data processing start time reaches the set value B, if yes, execute step S74, otherwise re-enter step S7; S74, determine whether the order of the branch switch is equal to 10, if so, assign order to 1 and return to step S61, otherwise, order is incremented by 1 and return to step S61; Among them, B>A.

9. The testing method according to claim 7 or 8, characterized in that: The data in the test result data packet includes the branch switch number no, the branch switch switching sequence number order, and the test result.

10. The test method according to claim 7 or 8, wherein the signal processing module further comprises ten instruction signal lights for indicating the selection numbers of all branch switch signals, characterized in that: In the step S61, after setting the branch switch switching sequence number to order, the corresponding command signal light is set.

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