Radio frequency signal 1DB compression point test method and computer device

Abstract

The invention relates to the field of radio frequency signal testing, in particular to a testing method of a radio frequency signal 1DB compression point and a computer device. According to the technical scheme, the method comprises the following steps: acquiring cable loss, setting the output power of a signal source at each frequency point according to the condition that the increase of input power is equal to the increase of output power under the condition that the cable loss is set in frequency, ensuring that a radio-frequency signal works in a linear region to solve a linear function of the signal, and testing the output power of the signal source at each frequency point through a power meter. Within the power working range of the radio frequency signal, performing curve fitting on the obtained off-line power data according to the actual output power of the radio frequency signal acquired by stepping k after the radio frequency signal passes through the tested device to obtain a fitted curve; and finally, calculating the input and output power at the 1DB compression point. The method is suitable for testing the 1DB compression point of the radio frequency signal.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency signal testing, and in particular to a testing method and a computer device for a 1DB compression point of a radio frequency signal. Background Art

[0002] In the field of RF technology, 1DB compression point is one of the important indicators to measure the linearity of RF power amplifiers. It indicates the input or output power level of the power amplifier when the gain is reduced by 1DB.

[0003] Currently, the 1DB compression point of the test signal mainly relies on the vector network analyzer. The test of 1DB compression point has some disadvantages that will affect the accuracy, efficiency and automation of the test. The disadvantages are as follows: 1) Requires a complex calibration process Before conducting precise tests, vector network analyzers usually need to be calibrated, including frequency calibration, amplitude calibration, and phase calibration, which increases test time, reduces test efficiency, and places high demands on the tester's skill level. If the calibration is improper, it will directly affect the accuracy of the 1DB test results. 2) Not suitable for high degree of automation When testing 1DB, the vector network analyzer needs to be recalibrated each time a parameter is changed due to the different devices under test (such as amplifiers and mixers) and inconsistent parameters. In addition, the output power of the signal source needs to be manually adjusted and the gain change of the output signal needs to be observed to determine the specific point of 1DB. This process is often difficult to fully automate, especially when dealing with complex signals or when test conditions need to be changed frequently (such as mixers), the degree of automation is even lower.

[0004] 3) High requirements for the test environment The 1DB test of the vector network analyzer has high requirements for the test environment, including temperature, humidity, electromagnetic interference, etc.; these factors may affect the test results. Therefore, when conducting the test, it is necessary to strictly control the test environment to ensure the accuracy and repeatability of the test results, which increases the difficulty and cost of the test and limits the scope of application of the test.

[0005] 4) Test results are affected by many factors In addition to the test environment and calibration process, the 1DB test results are also affected by many factors such as the linearity of the signal source output power, the loss of the test cable and attenuator, and the nonlinearity of the device under test. This requires testers to have rich experience and professional knowledge, which increases the difficulty of getting started with the test.

[0006] 5) The test time is long Since the calibration process is involved, the test conditions of the device under test are different, and changing the test conditions requires recalibration, which reduces the test efficiency and prolongs the test time.

[0007] In summary, the current vector network analyzer test of 1DB compression point has the disadvantages of requiring complex calibration, being unsuitable for high automation, having high requirements for the test environment, the test results being affected by multiple factors, and long test time. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a test method and computer device for the 1DB compression point of a radio frequency signal, which no longer uses a vector network analyzer, simplifies the test requirements and improves the test efficiency and the accuracy of the test results.

[0009] The present invention adopts the following technical solutions to achieve the above-mentioned purpose. In a first aspect, the present invention provides a method for testing a 1DB compression point of a radio frequency signal, comprising: S1. Obtain cable loss; Test cable loss and signal source error, = - , Indicates the cable power loss, Indicates the power obtained by the power meter test. represents the signal source power, f =0,...,step N, N represents the number of test frequency points, step is the step bandwidth, the signal source and cable are used as a measurement unit, the signal source power is increased in sequence in an automated manner, and the power loss of each frequency point is tested; S2, calculating the relationship between the input and output functions of the RF signal; When the frequency is set, the increase in input power is equal to the increase in output power. By setting the output power of the signal source at each frequency point and ensuring that the RF signal works in the linear region, the linear function of the signal is obtained: = x + b + , x represents the input signal, Indicates that the input signal is x The output power at b represents a constant; S3. Use a power meter to test the actual output power of the RF signal after passing through the device under test at each frequency point within the power operating range of the RF signal, with a step k acquisition method as follows: , x = m+ k (0,1,2...,z), z represents an integer; By collecting the output power at each input signal power, a set of offline power data is obtained. ; S4, performing curve fitting on the acquired offline power data; Assuming that an n-order polynomial is to be fitted, the curve equation after fitting is set to: = + +...+ + ; For each data point ( , ) Compute the polynomial in The predicted value at , and with the actual Compare and get the error , = - , is the output power of the signal source, Indicates that the input signal is Output power at When the sum of squares of the errors is minimized, the coefficients of the fitting curve equation are obtained. , , ,..., ; S = = , S represents the sum of squares of errors; S5. Calculate the input and output power at 1DB compression point; = +1, integrate the functions on both sides: Obtain x = k , that is, the output power at the 1DB compression point is ( k , ).

[0010] In a second aspect, the present invention provides a computer device, including a memory, wherein the memory stores program instructions, and when the program instructions are run, the above-mentioned test method for 1DB compression point of radio frequency signal is executed.

[0011] The beneficial effects of the present invention are: The present invention directly tests the output power of a signal through a power meter without complicated spectrum analysis, thus improving the test efficiency.

[0012] The present invention draws a theoretical linear region input-output curve by testing the measurement error of the signal source and the insertion loss of the cable, tests the output power under different signal source powers at each frequency point according to a certain step, makes a fitting curve for the discrete (input power, output power), and the theoretical curve minus the actual curve equals 1DB to determine the precise input and output power of the compression point, so that the result is more intuitive and accurate.

[0013] The present invention is applicable to different types of tested devices and input signals, does not require the construction of a complex test environment, is easy to use, and has strong versatility and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of a method for testing 1DB compression point of a radio frequency signal provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of raw output power data collected by sequentially increasing the power of an input signal according to a set step provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of a theoretical curve and a fitting curve provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0015] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0016] The present invention provides a method for testing the 1DB compression point of a radio frequency signal. Figure 1 As shown, the following steps are included: S1. Obtain cable loss; Testing cable loss and signal source error is mainly used to eliminate measurement errors. After the error data is obtained, it can be used continuously as long as the signal source and cable are not changed. = - , Indicates the cable power loss, Indicates the power obtained by the power meter test. represents the signal source power, f =0,...,step N, N represents the number of test frequency points, step is the step bandwidth, and the signal source and cable are used as a measurement unit. The signal source power is increased in sequence in an automated manner to test the power loss of each frequency point.

[0017] S2, calculating the relationship between the input and output functions of the RF signal; Calculate the theoretical input-output function relationship of the RF signal. The RF signal works in the linear region at low power. As the input signal power increases, the output power will slowly distort and lead to nonlinearity. That is, in theory, when the frequency is constant, the increase in input power is equal to the increase in output power. By setting the output power of the signal source at each frequency point as low as possible within the range, ensure that the RF works in the linear region to obtain the theoretical linear function of the signal: = x + b + , x represents the input signal, Indicates that the input signal is x The output power at b represents a constant; S3. Use a power meter to test the actual output power of the RF signal after passing through the device under test at each frequency point within the power operating range of the RF signal, with a step k acquisition method as follows: , x = m + k (0,1,2...,z), z represents an integer; By collecting the output power at each input signal power, a set of offline power data is obtained. ; S4, performing curve fitting on the acquired offline power data; The least squares method is used to fit the curve of this set of data, and a fitted curve is obtained. Assuming that an n-order polynomial is to be fitted, the equation of the fitted curve is = + +...+ x + ; For each data point ( , ) Compute the polynomial in The predicted value at , and with the actual Compare and get the error , = - , is the output power of the signal source, Indicates that the input signal is Output power at When the square sum of the errors is the smallest, it is the coefficient of the fitting curve equation that the present invention needs to obtain. , , ,..., ; S = = , S represents the sum of squares of errors; S5. Calculate the input and output power at 1DB compression point; = +1, where 1 represents 1DB, and the integral of the functions on both sides is: Obtain x = k , that is, the output power at the 1DB compression point is ( k , ).

[0018] The present invention is further described below in conjunction with actual tests.

[0019] Test conditions: Responsible for running the host computer of the automated test program, responsible for oscilloscope connection control, command issuance, acquisition of return data, data processing and curve drawing, result settlement and output; A signal source, generating an input signal to be tested; Oscilloscope board: receives the signal from the signal source and amplifies it; Power meter, used to measure and record the output power of the oscilloscope board; Test result analysis: like Figure 2 As shown, the power of the input signal is increased in appropriate steps, and the original output power data is collected.

[0020] like Figure 3 As shown, the theoretical curve is subtracted from the fitting curve, and the theoretical curve minus the actual curve is equal to 1DB to determine the input and output power of the exact compression point.

[0021] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for testing 1DB compression point of a radio frequency signal, characterized in that: include: S1. Obtain cable loss; Test cable loss and signal source error, = - , Indicates the cable power loss, Indicates the power obtained by the power meter test. represents the signal source power, f =0,...,step N, N represents the number of test frequency points, step is the step bandwidth, the signal source and cable are used as a measurement unit, the signal source power is increased in sequence in an automated manner, and the power loss of each frequency point is tested; S2, calculating the relationship between the input and output functions of the RF signal; When the frequency is set, the increase in input power is equal to the increase in output power. By setting the output power of the signal source at each frequency point and ensuring that the RF signal works in the linear region, the linear function of the signal is obtained: = x + b + , x represents the input signal, Indicates that the input signal is x The output power at b represents a constant; S3. Use a power meter to test the actual output power of the RF signal after passing through the device under test at each frequency point within the power operating range of the RF signal, with a step k acquisition method as follows: , x = m + k (0,1,2...,z), n>m, n and m represent the power operating range of the RF signal respectively, and z represents an integer; By collecting the output power at each input signal power, a set of offline power data is obtained. ; S4, performing curve fitting on the acquired offline power data; Assuming that an n-order polynomial is to be fitted, the curve equation after fitting is set to: = + +...+ x + ； For each data point ( , ) Compute the polynomial in The predicted value at , and with the actual Compare and get the error , = - , is the output power of the signal source, Indicates that the input signal is Output power at When the sum of squares of the errors is minimized, the coefficients of the fitting curve equation are obtained. , , ,..., ; S = = , S represents the sum of squares of errors; S5. Calculate the input and output power at 1DB compression point; = +1, integrate the functions on both sides: Obtain x = k , that is, the output power at the 1DB compression point is ( k , ).

2. A computer device comprising a memory, wherein the memory stores program instructions, characterized in that: When the program instructions are executed, the method for testing the 1DB compression point of the radio frequency signal as claimed in claim 1 is executed.

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