A Spectrum Spurious Test Method for Multi-Local Oscillation Frequency Point Microwave Frequency Converters

Abstract

The present invention provides a method for testing the spectral spurs of a multi-local oscillator frequency microwave frequency converter. First, the working bandwidth of the frequency converter is spectrally divided; then, the spectral spur distribution type is determined by judging the spectral spur positions under the first and last local oscillator frequency points of the frequency converter; then, according to the spectral spur distribution type, the spur search mode and search range are determined; the local oscillator frequency of the frequency converter is switched to the first local oscillator frequency point, the sampling points of the spectral trajectory of the working sub-band under the current local oscillator frequency are obtained, and the spectral spur search of the working sub-band under the current local oscillator frequency is completed according to the spur search mode determined in the above steps. Then, the frequency converter is switched to the next local oscillator frequency point, and the steps of obtaining the spectral trajectory sampling points and spectral search before are repeated to complete the test of the spectral spurs under the current local oscillator frequency. When each local oscillator frequency point of the frequency converter is traversed in sequence, the test of the spectral spurs of the working sub-band under each local oscillator frequency point of the multi-local oscillator frequency is completed.

Description

Technical Field

[0001] The present invention belongs to the field of microwave radio frequency testing in the electronic measurement industry, and relates to a testing method for the spectrum spurs of a microwave frequency converter with multiple local oscillator frequencies. Background Art

[0002] The microwave frequency converter is a key component of the satellite transponder subsystem, which can convert the frequency of the signal in the communication channel and filter and amplify it. Currently, the testing principle of the spectrum characteristics of microwave active components is to use the excitation response testing method. A microwave signal generator is used to generate an excitation signal and input it to the microwave frequency converter component, and then the output signal of the device under test is input to a spectrum analyzer for analysis.

[0003] A frequency converter with multiple local oscillator frequencies means that the microwave frequency converter has a local oscillator frequency step control function. Its input and output frequency conversion characteristics generally have two types: the first is that the input frequency remains fixed, and the output frequency changes correspondingly with the local oscillator frequency step control. The second is that the input frequency changes correspondingly with the local oscillator step control, and the output frequency remains fixed. The possible sources of the spectrum harmonic waves of the entire microwave frequency converter include the output products of the local oscillator mixing circuit, the output products of the radio frequency mixing circuit, the harmonic waves of the power supply switching frequency, and the mixed products of these frequency signals. The frequency mathematical relationship between the mixing products of the frequency converter is usually a linear relationship. Therefore, the frequency value of the mixing product is defined as f s = N*f LO ± M*f RF , where both M and N are arbitrary integer values. If the frequency conversion relationship of the frequency converter is f IF = f RF + f LO , and the local oscillator frequency step value is Δf, then the local oscillator frequency relationship between the adjacent two local oscillator frequencies LO1 and LO2 is f LO2 = f LO1 + Δf. From the frequency conversion relationship, the corresponding intermediate frequency output signal frequency can be obtained as f IF2 = f IF1 + Δf. Now assume that the mixing products of the radio frequency RF and the local oscillator LO at the adjacent two local oscillator frequencies are f s1 = N*f LO1 + M*f RF and f s2 = N*f LO2 + M*f RF . From the frequency transformation relationship, f s2 = f s1+N*Δf, the spurious signal of LO2 is shifted to the right by N*Δf relative to the spurious signal of LO1 in the frequency spectrum, and the intermediate frequency output signal IF2 is shifted to the right by Δf relative to IF1. Therefore, through spectrum analysis, it can be obtained that when the local oscillator LO frequency steps by Δf each time, the mixing products generated by the frequency converter (only considering the spurs falling within the working bandwidth) will have a relative spectrum offset of (N - 1)*Δf relative to the intermediate frequency signal IF in the frequency spectrum. This mixing product that follows the change of the local oscillator and is offset relative to the intermediate frequency output signal is called the local oscillator offset spur. When N = 1, the spectrum offset of the spur relative to the carrier signal is 0, and the spur is fixed relative to the carrier position. When N > 1, each time the local oscillator frequency point steps by Δf, the spectrum position of the spur relative to the carrier signal shifts, and the offset is (N - 1)*Δf.

[0004] In the actual debugging and testing process of multi-local oscillator frequency point microwave frequency converter products, traditional testing methods usually use manual operation of instruments or the use of an automatic testing system to test the products. There are mainly two common spur search methods when testing spectrum spurs: single-point frequency search and frequency range search. The main problems of this method are as follows:

[0005] (1) Affected by the local oscillator step control accuracy of the frequency converter, the background noise of the spectrum analyzer, and the aperture size of the sampling points of the spectrum analyzer, the spectrum distribution of the local oscillator offset spur has a certain randomness. When using the single-point frequency search or frequency range search method for spur testing, cumbersome frequency parameter settings are required, which brings certain difficulties to the spectrum automatic testing in the multi-local oscillator frequency point mode.

[0006] (2) The distribution of frequency spurs in multi-local oscillator frequency point microwave frequency conversion may be the result of a mixture of various types of spur signals. The limitation of using a single-mode frequency search method is that when there are various types of frequency spurs within the spectrum range to be measured, a single frequency search is difficult to flexibly handle the test scenario of the mixed distribution of multi-type spectrum spurs, and multiple measurements are required to complete the test, which greatly increases the test workload. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a spectrum spur testing method for a multi-local oscillator frequency point microwave frequency converter, which solves the problems of repeated frequency parameter setting and multi-type spectrum spur mixed testing in the spectrum spur testing process.

[0008] The technical solution adopted by the present invention is: a spectrum spur testing method for a multi-local oscillator frequency point microwave frequency converter, including:

[0009] S1. Divide the working spectrum bandwidth of the multi-local oscillator frequency point microwave frequency converter into spectrum region sub-bands, and perform equal-bandwidth spectrum partition on each local oscillator frequency point spectrum sub-band;

[0010] S2. Determine the first and last LO spectral spur pairs based on the distribution of the spectral spurs when the microwave frequency converter operates at the first and last LO frequency points respectively in the corresponding spectral sub-band partitions, and determine the spectral spur distribution type corresponding to the first and last LO spectral spur pairs according to the distribution positions of the first and last LO spectral spur pairs in the spectral partitions of their respective spectral sub-bands;

[0011] S3. Determine the spur search mode and search range according to the spectral spur distribution type;

[0012] S4. Switch the LO frequency point of the microwave frequency converter. When switching for the first time, make the microwave frequency converter operate at the first LO frequency point, and obtain the sampling points of the spectral trajectory data of the working sub-band at the current LO frequency point;

[0013] S5. Complete the spectral spur search of the working sub-band at the current LO frequency point according to the spur search mode and search range determined in S3;

[0014] S6. Repeat S4 and S5 to complete the spectral spur search of the working sub-bands at all K LO frequency points in turn, where K is a positive integer.

[0015] Further, in S1, for a microwave frequency converter with K LO frequency points, the output center carrier frequencies of the converter when operating at the first LO frequency point and the last LO frequency point are IF1 and IF respectively k , the LO frequency step value is Δf, and IF k = IF1 + k * Δf, where k = 0, 1, 2,... K - 1, and the bandwidth of the working sub-band at the LO frequency point is Span. Then the working spectral bandwidth range of the microwave frequency converter is IF1 - 1 / 2Span ~ IF k + 1 / 2Span;

[0016] Divide the working spectral bandwidth range into K spectral sub-bands, and divide each spectral sub-band corresponding to the LO frequency point into M equal-bandwidth spectral partitions.

[0017] Further, in S2, determining the first and last LO spectral spur pairs according to the distribution of the spectral spurs when the microwave frequency converter operates at the first and last LO frequency points respectively in the corresponding spectral sub-band partitions includes:

[0018] Switch the LO frequency point of the microwave frequency converter to the first LO frequency point, and record the positions and amplitudes of all the spurs in the spectral sub-band when the converter operates at the first LO frequency point; if there are multiple spectral spurs in the same spectral partition, then record the maximum amplitude of the spectral spurs in this spectral partition;

[0019] Switch the operating local oscillator frequency point of the microwave frequency converter to the last local oscillator frequency point, and record the positions and amplitudes of the spectral partitions where all spurs in the spectral sub-band are located when the frequency converter operates at the last local oscillator frequency point; if there are multiple spectral spurs in the same spectral partition, record the maximum amplitude of the spectral spurs in this spectral partition.

[0020] According to the number, partition positions and amplitudes of the spectral spurs when the microwave frequency converter operates at the first local oscillator frequency point and the last local oscillator frequency point, determine two spectral spurs with an amplitude difference less than the set threshold value V limit and with coupled partition positions in the partition as a pair of first and last local oscillator spectral spurs.

[0021] Further, in S2, determine the spectral spur distribution type corresponding to the pair of first and last local oscillator spectral spurs according to the distribution positions of the pair of first and last local oscillator spectral spurs in the spectral partitions of their respective spectral sub-bands, including three types:

[0022] The first type: The two spurs of the pair of first and last local oscillator spectral spurs are respectively located in the same spectral partition of their respective spectral sub-bands;

[0023] The second type: The two spurs of the pair of first and last local oscillator spectral spurs are respectively located in different spectral partitions of their respective sub-bands and are on the same side of the center carrier of the sub-band, that is, the spectral ranges of the two partitions are both higher or both lower than the sub-band center carrier frequency;

[0024] The third type: The two spurs of the pair of first and last local oscillator spectral spurs are respectively located in different spectral partitions of their respective sub-bands and are both distributed on both sides of the carrier, that is, the spectral range of one partition is lower than the sub-band center carrier frequency and the spectral range of the other partition is higher than the sub-band center carrier frequency.

[0025] Further, in S3, determine the spur search mode and search range according to the spectral spur distribution type, including:

[0026] According to the three types of spectral spur distribution types determined in S2, perform spectral spur search on all local oscillator point spectral sub-bands respectively using the search modes of fixed region search, sideband search and combined search.

[0027] Further, the fixed region search mode includes:

[0028] Find the sampling point with the largest amplitude among the sampling points corresponding to the specified single spectral partition in each sub-band; for the first type of the spectral spur distribution type determined in S2, if the spectral spurs of the first and last local oscillator points are both located in the same spectral partition, perform fixed region search on this partition.

[0029] Further, the sideband search mode includes:

[0030] Based on the M local oscillator sub - band spectral partitions divided in S1, the H half - region and the L half - region are successively divided into search side - bands, and each search side - band consists of several consecutive spectral partitions; the division range of the search side - band in the H half - region is from the partition to the H1 partition, where the division range of the search side - band in the L half - region is from the partition to the L1 partition, where side - band search is to find the sampling point with the largest amplitude within the corresponding side - band partition range;

[0031] For the second type of the spectral spurious distribution type determined in S2, if the first and last local oscillator spurs f1 and f k are located in the H half - region, then the partition H k closest to the center reference point of the spectral sub - band among the spectral partitions where the first and last local oscillator spurs f1 and f s are located is used as the starting partition of the side - band search range, the ending partition of the side - band search range is H1, and the side - band search range is H S to H1; if the first and last local oscillator spurs f1 and f k are located in the L half - region, then the partition L k closest to the center reference point of the spectral sub - band among the spectral partitions where the first and last local oscillator spurs f1 and f s are located is used as the starting partition of the side - band search range, the ending partition of the side - band search range is L1, and the side - band search range is L s to L1.

[0032] Furthermore, the combined search mode includes:

[0033] For the third type of the spectral spurious distribution type determined in S2, a combined method of fixed - region search and side - band search is used for spectral spurious search:

[0034] For each partition within the frequency range from the sub - band partition where the spur f1 of the first and last local oscillator frequencies belongs to the center reference point of the sub - band, fixed - region search is respectively carried out. If the sub - band partition where f1 is located is L i or H i , then the range of fixed - region search is for the partitions within the range from L i to or for the partitions within the range from H i to , and times of fixed - region search are respectively carried out;

[0035] For the one - half sub - band bandwidth spectral range where the spur f k of the last local oscillator frequency is located, one - time side - band search is carried out. The side - band search range is: if f kThe frequency is greater than f1, and the sideband search range is Partitioned to H1 if f k The frequency is less than f1, and the sideband search range is Partitioned to the L1 partition;

[0036] Among all The maximum value of the amplitudes in the secondary zoning search and the single-sideband search results is taken as the combined search test result.

[0037] Furthermore, in S4, switch the local oscillator frequency point of the frequency converter. When switching for the first time, make the frequency converter work at the first local oscillator frequency point, and obtain the sampling points of the working sub-band spectrum trajectory data at the current local oscillator frequency point, including:

[0038] The allocation relationship between the working sub-band spectrum partition of the local oscillator frequency point and the Z sampling points of the spectrum trajectory data obtained in S4 is: divide the Z sampling points into M partitions, and use the sampling point of the sub-band center frequency point, that is, the point as the spectrum sub-band center reference point; set the number of de-embedded sampling points at the center carrier frequency point to 2*V, and set the point to the point range of sampling points as the de-embedded sampling points of the center carrier;

[0039] The sampling points with frequencies lower than the center reference point are divided into partitions called the L half-region, and the sampling points with frequencies higher than the center reference point are divided into partitions called the H half-region, where L1 to partitions and to H1 partitions are allocated sampling points, and The sampling points of the partition are ; Z is an odd number.

[0040] Furthermore, in S5, if the number of spurious pairs of the first and last local oscillator spectra determined in S2 is P, where P is a positive integer, then according to the spurious type of the spurious pairs of the first and last local oscillator spectra determined in S2 and the spurious spectrum search mode and search range determined in S3, complete the P times of spurious spectrum search for the sub-band of the current local oscillator frequency point.

[0041] The advantages of the present invention compared with the prior art are:

[0042] (1) By defining the spectral partition, the reference coordinate system of spectral spurs is converted from the absolute frequency axis to the spectral partition relative to the carrier, which solves the problem of repeatedly setting frequency parameters during the spectral spur test. In the reference system of the spectral partition relative to the carrier, only the corresponding search modes and search regions for all sub-bands need to be specified once. Applying this method to the test program of the automatic test system reduces the difficulty of developing and using the automatic test program, simplifies the operation steps of the testers, has good product applicability, and improves the test efficiency of the multi-local oscillator frequency point frequency converter.

[0043] (2) Aiming at the three distribution characteristics of the spectral spurs of the frequency converter, three search modes of fixed-region search, sideband search, and combined search are adopted. When there are spectral spurs in the multi-local oscillator frequency point microwave frequency converter, through flexible combination and configuration, the proposed method can achieve the mixed test of various types of spectral spurs in a single spectral scan. Description of the Drawings

[0044] Figure 1 is a flowchart of a spectral spur test method for a multi-local oscillator frequency point microwave frequency converter;

[0045] Figure 2 is a diagram showing the division of the working frequency band range of a microwave frequency converter with 8 local oscillator frequency points into 8 spectral sub-bands;

[0046] Figure 3 is a diagram showing the division of the spectral sub-band of the LO1 local oscillator frequency point with a center carrier frequency of 25300 MHz into 10 spectral partitions;

[0047] Figure 4 is a schematic diagram of the mixed distribution of two different types of spectral spurs in the spectral sub-band;

[0048] Figure 5 is a schematic diagram of performing fixed-region search and sideband search on two different groups of first and last local oscillator spectral spur pairs respectively. Detailed Embodiment

[0049] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0050] The present invention provides a spectral spur test method for a multi-local oscillator frequency point microwave frequency converter, including the following steps:

[0051] (1) Divide the spectral bandwidth of the multi-local oscillator frequency point microwave frequency converter into spectral sub-bands, and divide each local oscillator frequency point spectral sub-band into equal-bandwidth spectral partitions;

[0052] (2) Determine the spectral spur distribution type according to the spectral partition positions where the spectral spurs are located when the microwave frequency converter operates at the first and last local oscillator frequency points;

[0053] (3) Determine the spurious search mode and search range according to the type of spurious spectrum distribution;

[0054] (4) Switch the operating local oscillator frequency point of the frequency converter. When switching for the first time, make the frequency converter operate at the first local oscillator frequency point, and obtain the sampling points of the spectral trajectory data of the working sub-band at the current local oscillator frequency point;

[0055] (5) Complete the spurious spectrum search of the working sub-band at the current local oscillator frequency point according to the spurious search mode and search range determined in step (3);

[0056] (6) Repeat steps (4) and (5) to complete the spurious spectrum search of the working sub-bands at all K local oscillator frequency points in sequence.

[0057] In step (1), for a microwave frequency converter with K local oscillator frequency points, the output center carrier frequencies of the frequency converter when operating at the first local oscillator frequency point and the last local oscillator frequency point are IF1 and IF respectively k , the local oscillator frequency step value is Δf, IF k = IF1 + k * Δf, k = 0, 1, 2,... K - 1, the bandwidth of the working sub-band at the local oscillator frequency point is Span, then the working spectrum bandwidth range of the microwave frequency converter is IF1 - 1 / 2Span ~ IF k + 1 / 2Span. First, divide K spectral sub-bands within the working spectrum bandwidth range, and divide M equal-bandwidth spectral partitions for each spectral sub-band corresponding to the local oscillator frequency point. The allocation relationship between the spectral partition of the working sub-band at the local oscillator frequency point and the Z sampling points (the sampling points range from 0 to Z - 1, and Z is default to be odd) of the spectral trajectory data obtained in step (4) is: divide the Z sampling points into M partitions, and use the sampling point at the center frequency point of the sub-band, that is, the th point as the center reference point of the spectral sub-band. Set the number of de-embedded sampling points at the center carrier frequency point to 2 * V, and use the sampling points within the range from the th point to the th point as the de-embedded sampling points of the center carrier. Then divide the sampling points with frequencies lower than the center reference point into partitions (referred to as the L half-region) in ascending order of frequency, and divide the sampling points with frequencies higher than the center reference point into partitions (referred to as the H half-region) in ascending order of frequency. Among them, the number of sampling points allocated to the partitions from L1 to and from to H1 is each, and the number of sampling points in the and partitions is each.

[0058] In step (2), the first and last local oscillator spectral spurs are determined according to the distribution of the spectral spurs of the multi-local oscillator frequency microwave frequency converter when it works at the first local oscillator frequency point and the last local oscillator frequency point in the corresponding spectral sub-band partitions. The specific process is as follows:

[0059] (2a) Switch the local oscillator frequency point of the frequency converter to the first local oscillator frequency point, and record the positions and amplitudes of all spurs in the spectral sub-band when the frequency converter works at the first local oscillator frequency point. If there are multiple spectral spurs in the same spectral partition, record the maximum amplitude of the spectral spurs in this spectral partition.

[0060] (2b) Switch the local oscillator frequency point of the frequency converter to the last local oscillator frequency point, and record the positions and amplitudes of all spurs in the spectral sub-band when the frequency converter works at the last local oscillator frequency point. If there are multiple spectral spurs in the same spectral partition, record the maximum amplitude of the spectral spurs in this spectral partition.

[0061] (2c) According to the number, partition positions, and amplitudes of the spectral spurs recorded above when the frequency converter works at the first and last local oscillator frequency points, determine two spectral spurs with an amplitude difference less than the set threshold value and a coupling relationship in the partition positions as a pair of first and last local oscillator spectral spurs.

[0062] In step (2), according to the distribution positions of the first and last local oscillator spectral spurs in the spectral partitions of their respective spectral sub-bands, determine the spur types corresponding to the first and last local oscillator spectral spurs. There are three types of distributions of the first and last local oscillator spectral spurs of the multi-local oscillator frequency converter as follows:

[0063] The first type: The two spurs of the first and last local oscillator spectral spur pair are respectively located in the same spectral partition of their respective spectral sub-bands;

[0064] The second type: The two spurs of the first and last local oscillator spectral spur pair are respectively located in different spectral partitions of their respective sub-bands and are on the same side of the center carrier of the sub-band, that is, the spectral ranges of the two partitions are both higher or both lower than the center carrier frequency of the sub-band;

[0065] The third type: The two spurs of the first and last local oscillator spectral spur pair are respectively located in different spectral partitions of their respective sub-bands and are both distributed on both sides of the carrier, that is, the spectral range of one partition is lower than the center carrier frequency of the spectral sub-band, and the spectral range of the other partition is higher than the center carrier frequency of the spectral sub-band.

[0066] In step (3), according to the three cases of the spectral spur types determined in step (2), three different search modes of fixed-region search, sideband search, and combined search are respectively adopted for spectral spur search in all local oscillator frequency point spectral sub-bands.

[0067] Fixed-region search mode: That is, find the sampling point with the largest amplitude among the sampling points corresponding to a single specified spectral partition in each sub-band. The fixed-region search mode is for the first type of spurious in step (2). If the spectral spurs of the first and last local oscillator points are both located in the same spectral partition, then perform fixed-region search on this partition;

[0068] Sideband search mode: Based on the M spectral partitions of the local oscillator sub-bands divided in step (1), divide the H half-region and the L half-region into search sidebands respectively, and each search sideband consists of several consecutive spectral partitions. The division range of the search sidebands in the H half-region is from the partition to the H1 partition, where The division range of the search sidebands in the L half-region is from the partition to the L1 partition, where The sideband search is to find the sampling point with the largest amplitude within the corresponding sideband partition range. The sideband search mode is for the determined second type of spurious in step (2). If the spurs f1 and f of the first and last local oscillator points k are located in the H half-region, take the partition H k which is the closest to the center reference point of the spectral sub-band among the spectral partitions where the spurs f1 and f of the first and last local oscillator points are located s as the starting partition of the sideband search range, and the ending partition of the sideband search range is H1. If the spurs f1 and f of the first and last local oscillator points k are located in the L half-region, take the partition L k which is the closest to the center reference point of the spectral sub-band among the spectral partitions where the spurs f1 and f of the first and last local oscillator points are located s as the starting partition of the sideband search range, and the ending partition of the sideband search range is L1, and the sideband search range is L s ~L1;

[0069] Combined search mode: For the determined third type of spurious in step (2), adopt a combined method of fixed-region search and sideband search for spectral spurious search. For each partition within the frequency range from the sub-band partition where the spur f1 of the first and last local oscillator points belongs to the center reference point of the sub-band, perform fixed-region search respectively. If the sub-band partition where f1 is located is L i or H i , then the range of fixed-region search is the partitions within the range from L i to or the partitions within the range from H i to , and perform times of fixed-region search respectively. For the one-half sub-band bandwidth spectral range where the spur f of the last local oscillator point k is located, perform one sideband search. The sideband search range is: If the frequency of f k is greater than f1, the sideband search range is Partition to H1, if the sideband f k has a frequency less than f1, the sideband search range is Partition to the L1 partition. Finally, among all the secondary fixed-region search and single-sideband search results, take the maximum amplitude value as the combined search test result.

[0070] In step (5), if the number of spurious pairs of the first and last local oscillator spectra determined in step (2) is P, and P is a positive integer, then according to the spurious type of the spurious pairs of the first and last local oscillator spectra determined in step (2) and the spurious search mode and search range determined in step (3), complete P times of spurious spectrum searches for the current local oscillator frequency sub-band in step (5);

[0071] Embodiment 1

[0072] See the appendix Figure 1 , which is a flowchart of a method for testing spurious spectra of a multi-local oscillator frequency microwave frequency converter provided by this embodiment; first, divide the working bandwidth of the frequency converter into spectral bands, then determine the spurious spectrum distribution type by judging the spurious positions under the first and last local oscillator frequencies of the frequency converter, then determine the spurious search mode and search range according to the spurious distribution type, switch the local oscillator frequency of the frequency converter to the first local oscillator frequency, obtain the sampling points of the working sub-band spectral trajectory at the current local oscillator frequency, complete the spurious spectrum search of the working sub-band at the current local oscillator point according to the spurious search mode determined in the previous steps, then switch the frequency converter to the next local oscillator frequency, and repeat the steps of obtaining spectral trajectory sampling points and spectral search in the previous steps to complete the spurious spectrum test at the current local oscillator frequency. When traversing each local oscillator frequency of the frequency converter in turn, the spurious spectrum test of the working sub-band at each local oscillator frequency of the multi-local oscillator frequency is completed.

[0073] Now set the number of local oscillator frequencies K = 8 of the multi-local oscillator frequency microwave frequency converter to be measured, the working spectral bandwidth range is 25275 MHz to 25745 MHz, the local oscillator frequency step is 60 MHz, the spectral sub-band bandwidth Span = 50 MHz, the input frequency of the frequency converter is 3760 MHz, IF1 = 25300 MHz, IF8 = 25720 MHz, LO1 = 21540 MHz, LO8 = 21960 MHz, and the spurious determination threshold value V limit = 1 dBm. The number of sampling points for collecting spectral trajectory data during the test is 1001 points.

[0074] The specific steps of the present invention are as follows:

[0075] Step 1: Divide 8 spectral sub-bands with a bandwidth of 50 MHz within the working spectral bandwidth range of 25275 MHz to 25745 MHz of the microwave frequency converter. The center frequencies of the spectral sub-bands are IF i+1= 25300 MHz + i * 60 MHz, where i = 0, 1, 2, 3, 4, 5, 6, 7. The relationship between the spectral sub - band division and the microwave frequency converter frequency is as shown in Figure 2 and Table 1.

[0076] Table 1

[0077]

[0078] Then, divide the 50 - MHz bandwidth of the spectral sub - band corresponding to each local oscillator frequency point into M = 10 equal - bandwidth spectral partitions, and the bandwidth of each partition is 5 MHz. The division relationship of the 1001 sampling points of the spectral sub - band corresponding to the first local oscillator frequency point 21540 MHz is as shown in Figure 3 and Table 2. Figure 3 The frequency of the center carrier frequency IF1 in [reference] is 25300 MHz, its de - embedded sampling points are 20, the de - embedded bandwidth is 1 MHz, and the de - embedded bandwidth frequency range is 25299.5 - 25300.5 MHz.

[0079] Table 2

[0080] Partition number Sampling point range Frequency range L1 partition 0～99 25275 - 25280 MHz L2 partition 100～199 25280 - 25285 MHz L3 partition 200～299 25285 - 25290 MHz L4 partition 300～399 25290 - 25295 MHz L5 partition 400～489 25295 - 25299.5 MHz De - embedding bandwidth 490～510 25299.5 - 25300.5 MHz H5 partition 511～600 25300.5 - 25305 MHz H4 partition 601～700 25305 - 25310 MHz H3 partition 701～800 25310 - 25315 MHz H2 partition 801～900 25315 - 25320 MHz H1 partition 901～1000 25320 - 25325 MHz

[0081] Step 2: Switch the local oscillator frequency point of the frequency converter to the first local oscillator frequency point, input a 3760 - MHz excitation signal to the frequency converter, and record the positions and amplitudes of all spurs in the spectral partitions within the spectral sub - band of the first local oscillator frequency point LO1. Then switch the local oscillator frequency point to the last local oscillator frequency point LO8 and record the positions and amplitudes of all spurs in the spectral partitions within the spectral sub - band of LO8. As shown in Figure 4 , the spur f 1.1 in the spectral sub - band of LO1 is located in the L2 partition, with an amplitude V 1.1 = - 50 dBm; f 1.2 is located in the H4 partition, with an amplitude V 1.2 = - 60 dBm. The spur f 8.1 in the spectral sub - band of LO8 is located in the L2 partition, with an amplitude V 8.1 = - 50 dBm; f 8.2 is located in the H1 partition, with an amplitude V 8.2 = - 60 dBm. From V 8.1 - V 1.1 <V limit and V 8.2 - V 1.2 <V limit , it can be determined that f 1.1 and f 8.1 are a pair of first - and - last local oscillator spectral spurs, and f 1.2 and f 8.2 are a pair of first - and - last local oscillator spectral spurs.

[0082] Step 3: As can be seen from the result in Step 2, f 1.1 and f 8.1 The first and last local oscillator spectrum spurious pairs are respectively located in the L2 partition of their respective spectrum sub-bands, and it is confirmed that their spurious type is the first spurious distribution type. f 1.2 and f 8.2 The first and last local oscillator spectrum spurious pairs are respectively located in the H4 partition and the H1 partition of their respective spectrum sub-bands, and it is confirmed that their spurious type is the second spurious distribution type. For all spectrum sub-bands of LO1 to LO8, a combined method of fixed-region search mode and sideband search mode is used for searching. Fixed-region search is performed on the L2 partition, and sideband search is performed on the H4 - H1 partition. As Figure 5 shown is a schematic diagram of the search range for the fixed-region search of the L2 partition and the sideband search of the H4 - H1 partition of the LO1 spectrum sub-band.

[0083] Step 4: Switch the local oscillator frequency point of the frequency converter to LO j frequency point, j = 1, 2, 3, 4, 5, 6, 7, 8. Obtain 1001 sampling points of the corresponding LO sub-band spectrum trajectory data. When Step 4 is executed for the first time, switch the frequency converter to the LO1 local oscillator frequency to obtain the sampling point data of the LO1 sub-band spectrum trajectory;

[0084] Step 5: From the results of Step 2 and Step 3, it can be obtained that a fixed-region search and a sideband search are respectively performed once within the current LO j spectrum sub-band where the microwave frequency converter is located. The fixed-region search range in the spectrum sub-band is the L2 partition, and the sideband search range is the H4 - H1 partition. Take the maximum value of the two search results.

[0085] Step 6: Repeat Step 4 and 5 to sequentially complete the spurious search for the spectrum sub-bands of the LO2 - LO8 local oscillator frequency points.

[0086] The parts not detailed in the present invention belong to the well-known technologies in the art.

Claims

1. A spectrum spurious test method for a multi-local oscillator frequency point microwave frequency converter, characterized in that Including: S1. Perform sub-band division on the working spectral bandwidth of a multi-local oscillator frequency microwave frequency converter, and perform equal-bandwidth spectral partition division on each local oscillator frequency spectral sub-band; S2. Determine the first and last local oscillator spectral spurious pairs according to the distribution of the spectral spurs of the microwave frequency converter when it works at the first and last local oscillator frequencies in the corresponding spectral sub-band partitions, and determine the spectral spur distribution type corresponding to the first and last local oscillator spectral spurious pairs according to the distribution positions of the first and last local oscillator spectral spurious pairs in the spectral partitions of their respective spectral sub-bands; S3. Determine the spurious search mode and search range according to the spectral spur distribution type; S4. Switch the working local oscillator frequency of the microwave frequency converter. When switching for the first time, make the microwave frequency converter work at the first local oscillator frequency, and obtain the sampling points of the working sub-band spectral trajectory data at the current local oscillator frequency; S5. Complete the spectral spur search for the working sub-band at the current local oscillator frequency according to the spurious search mode and search range determined in S3; S6. Repeat S4 and S5 to complete the spectral spur search for the working sub-bands of all K local oscillator frequencies in sequence, where K is a positive integer.

2. The spectrum spurious test method for a multi-LO microwave frequency converter according to claim 1, characterized in that: In S1, for a microwave frequency converter with K local oscillator frequency points, the output center carrier frequencies of the frequency converter operating at the first local oscillator frequency point and the last local oscillator frequency point are IF1 and IF respectively. k , the local oscillator frequency step value is Δf, and IF k = IF1 + k * Δf, where k = 0, 1, 2, … K - 1, and the working sub-band bandwidth of the local oscillator frequency point is Span. Then the working frequency spectrum bandwidth range of the microwave frequency converter is IF1 - 1 / 2Span to IF k + 1 / 2Span; Divide K spectral sub-bands within the working spectral bandwidth, and divide M equal-bandwidth spectral partitions for each spectral sub-band corresponding to each local oscillator frequency.

3. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 2, characterized in that: In S2, determining the first and last local oscillator spectral spurious pairs according to the distribution of the spectral spurs of the microwave frequency converter when it works at the first and last local oscillator frequencies in the corresponding spectral sub-band partitions includes: Switch the working local oscillator frequency of the microwave frequency converter to the first local oscillator frequency, and record the positions and amplitudes of all spurs in the spectral sub-band when the frequency converter works at the first local oscillator frequency; if there are multiple spectral spurs in the same spectral partition, record the maximum amplitude of the spectral spurs in this spectral partition; Switch the working local oscillator frequency of the microwave frequency converter to the last local oscillator frequency, and record the positions and amplitudes of all spurs in the spectral sub-band when the frequency converter works at the last local oscillator frequency; if there are multiple spectral spurs in the same spectral partition, record the maximum amplitude of the spectral spurs in this spectral partition; According to the number, partition position, and amplitude of the spectral spurs when the recorded microwave frequency converter operates at the first local oscillator frequency point and the last local oscillator frequency point, determine two spectral spurs with an amplitude difference less than the set threshold value V limit and a coupling property in the partition positions where they are located as a pair of first and last local oscillator spectral spurs.

4. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 3, characterized in that: In S2, determining the spectral spur distribution type corresponding to the first and last local oscillator spectral spurious pairs according to the distribution positions of the first and last local oscillator spectral spurious pairs in the spectral partitions of their respective spectral sub-bands includes three types: The first type: The two spurs of the first and last local oscillator spectral spurious pairs are respectively located in the same spectral partition of their respective spectral sub-bands; The second type: The two spurs of the first and last local oscillator spectral spurious pairs are respectively located in different spectral partitions of their respective sub-bands and are on the same side of the sub-band center carrier, that is, the spectral ranges of the two partitions are both higher or both lower than the sub-band center carrier frequency; The third type: The two spurs of the first and last local oscillator spectral spurious pairs are respectively located in different spectral partitions of their respective sub-bands and are both distributed on both sides of the carrier, that is, the spectral range of one partition is lower than the sub-band center carrier frequency, and the spectral range of the other partition is higher than the sub-band center carrier frequency.

5. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 4, characterized in that: In S3, determining the spurious search mode and search range according to the spectral spur distribution type includes: According to the three types of spectral spurious distribution types determined in S2, spectral spurious searches are performed on all local oscillator point spectral sub-bands using search modes of fixed-region search, sideband search, and combined search respectively.

6. A spectrum spurious test method for a multi-LO microwave frequency converter according to claim 5, characterized in that: The fixed-region search mode includes: Finding the sampling point with the largest amplitude among the sampling points corresponding to a single spectral partition specified in each sub-band; for the first type of spectral spurious distribution type determined in S2, if the spectral spurs of the first and last local oscillator points are both located in the same spectral partition, then the fixed-region search is applied to this partition.

7. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 5, characterized in that: The sideband search mode includes: Based on the M local oscillator sub-band spectral partitions divided in S1, the H half-region and the L half-region are successively divided into search sidebands, where each search sideband consists of several consecutive spectral partitions; the division range of the search sidebands in the H half-region is from the partition to the H1 partition, where the division range of the search sidebands in the L half-region is from the partition to the L1 partition, where sideband search is to find the sampling point with the largest amplitude within the corresponding sideband partition range described above; For the second type of the determined spectral spurious distribution type in S2, if the first and last local oscillator spurs f1 and f k are located in the H half-region, then the partition H k in the spectral partition where the first and last local oscillator spurs f1 and f s are located and that is closest to the center reference point of the spectral sub-band is used as the starting partition of the sideband search range, the ending partition of the sideband search range is H1, and the sideband search range is from H S to H1; if the first and last local oscillator spurs f1 and f k are located in the L half-region, then the partition L k in the spectral partition where the first and last local oscillator spurs f1 and f s are located and that is closest to the center reference point of the spectral sub-band is used as the starting partition of the sideband search range, the ending partition of the sideband search range is L1, and the sideband search range is from L s to L1.

8. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 5, characterized in that: The combined search mode includes: For the third type of spectral spurious distribution type determined in S2, a combined method of fixed-region search and sideband search is used for spectral spurious search: For each partition within the frequency range from the sub-band partition to which the spurious f1 of the first and last local oscillator frequency points belongs to the sub-band center reference point, fixed-region search is adopted. If the sub-band partition where f1 is located is L i or H i , then the range of the fixed-region search is the partitions within the range from L i to or the partitions within the range from H i to , and the fixed-region search is performed separately times; For the spurious of the last local oscillator frequency point f k Perform a sideband search on the spectral range of half of the sub-band bandwidth where it is located. The sideband search range is: If the frequency of f k is greater than f1, the sideband search range is Partitioned to H1. If the frequency of f k is less than f1, the sideband search range is Partitioned to the L1 partition; Among all Take the maximum amplitude value in the secondary fixed-region search and the single-sideband search results as the combined search test result.

9. A spectrum spurious test method for a multi-LO frequency point microwave frequency converter according to claim 5, characterized in that: In S4, switch the local oscillator frequency point of the frequency converter. When switching for the first time, make the frequency converter work at the first local oscillator frequency point, and obtain the sampling points of the working sub-band spectral trajectory data at the current local oscillator frequency point, including: The allocation relationship between the spectrum sub - zone partition of the local oscillator frequency point operating sub - band and the Z sampling points of the spectrum trajectory data obtained in S4 is as follows: Divide the Z sampling points into M partitions, and use the sampling point of the sub - band center frequency, that is, the point as the spectrum sub - band center reference point; Set the number of de - embedded sampling points of the center carrier frequency point to 2*V, and use the sampling points in the range from the point to the point as the de - embedded sampling points of the center carrier; The sampling points with frequencies lower than the central reference point are divided into sub-zones called the L half-zone, and the sampling points with frequencies higher than the central reference point are divided into sub-zones called the H half-zone, where the allocated number of sampling points for the L1 to sub-zones and to the H1 sub-zone is points, and the sampling points of the sub-zone are points; Z is an odd number.

10. A method for testing the spectral spurs of a multi-LO microwave frequency converter according to claim 9, characterized in that: In S5, if the number of spectral spurious pairs of the first and last local oscillators determined in S2 is P, where P is a positive integer, then according to the spurious type of the spectral spurious pairs of the first and last local oscillators determined in S2 and the spectral spurious search mode and search range determined in S3, complete P spectral spurious searches for the sub-band of the current local oscillator frequency point.

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