A high-precision multi-channel analog quantity acquisition interface calibration method

Abstract

This invention belongs to the field of computer applications, and particularly relates to a high-precision multi-channel analog signal acquisition interface calibration method. The method includes: Step 1, calculating the gain coefficient of the corrected A / D converter using a full-amplitude level calibration method; Step 2, calculating the voltage value of each channel of each switch; Step 3, using a multiple measurement averaging calibration method, performing multiple acquisitions on each channel of each switch, removing the maximum and minimum values ​​from the acquired code values, and averaging the results to obtain the average voltage value for each channel of each switch; Step 4, comprehensively applying the gain coefficient from Step 1 and the average voltage value from Step 3 to calculate the final calibrated acquisition value to complete the calibration of the high-precision analog signal interface. This invention eliminates various errors on the analog signal acquisition interface by comprehensively using three different calibration methods, thus meeting the high-precision requirements of airborne system analog signal acquisition interfaces.

Description

Technical Field

[0001] This invention belongs to the field of computer applications, and in particular relates to a high-precision multi-channel analog signal acquisition interface calibration method. Background Technology

[0002] Airborne systems, including subsystems such as avionics, flight control, electromechanical, and hydraulic systems, typically generate a large amount of terminal data. This data includes various types of digital signals as well as a significant amount of analog signals. Analog signals need to be converted into digital signals before transmission and processing on the bus. The integrated processing equipment generates specific control outputs based on these analog-to-digital conversions to achieve different control functions for each system. The accuracy and reliability of the data acquisition process also affect the stability and reliability of the entire airborne system. Existing analog signal acquisition circuits often perform simple acquisition and correction, resulting in low accuracy and an inability to accurately reflect the characteristics of external systems. Summary of the Invention

[0003] The purpose of this invention is:

[0004] This invention provides a high-precision multi-channel analog signal acquisition interface calibration method. The method employs full-amplitude level calibration, ground level calibration, and multiple measurement averaging calibration, and comprehensively utilizes these three calibration methods to complete the calibration of the high-precision analog signal interface.

[0005] The solution of this invention is:

[0006] A high-precision multi-channel analog signal acquisition interface calibration method includes the following steps:

[0007] Step 1 uses the full-amplitude level calibration method to calculate the gain coefficient of the corrected A / D converter;

[0008] Step 2: Calculate the voltage value of each channel of each switch;

[0009] Step 3 uses the multiple measurement averaging calibration method. Multiple measurements are collected for each channel of each switch, and the maximum and minimum values ​​of the collected code values ​​are removed and averaged to obtain the average voltage value for each channel of each switch.

[0010] Step 4 combines the gain coefficient from Step 1 and the averaged voltage value from Step 3 to calculate the final calibrated acquisition value and complete the calibration of the high-precision analog interface.

[0011] Further, step 1 specifically includes:

[0012] Step 1.1 Provide a high-precision reference voltage source Vref at full amplitude level for the A / D conversion device;

[0013] Step 1.2 Connect the reference voltage source Vref to the analog input terminal of the A / D converter;

[0014] Step 1.3 The A / D converter acquires the code value corresponding to Vref as Cref, and consults the A / D converter manual to obtain the theoretical code value corresponding to Vref as Ct;

[0015] Step 1.4 Calculate the gain coefficient of the corresponding device after correction: C FIX =Ct / Cref.

[0016] Furthermore, step 2 specifically includes,

[0017] The analog ground is connected to one of the paths of each multiplexer, and the signals to be acquired are connected to the other paths of each multiplexer to obtain the voltage values ​​of each channel of each switch.

[0018] Furthermore, step 3 specifically includes: when performing ADC acquisition on any channel, under the premise of sufficient conversion time, multiple conversions are performed, and after removing a certain proportion of the maximum and minimum values ​​from the conversion results, the average value is calculated to achieve the multiple measurement averaging calibration method.

[0019] Furthermore, step 4 specifically includes:

[0020] Step 4.1 Using C FIX The corrected voltage value V is calculated based on the first averaged voltage value. GND The first averaged voltage value is the voltage value obtained when the switch is switched to ground;

[0021] Step 4.2 Using C FIX Calculate the corrected voltage value V corresponding to the second averaged voltage value. SIG The second averaged voltage value is the voltage value obtained when the switch is switched to the signal;

[0022] Step 4.3 V SIG Subtract V GND This is the final calibrated collected value.

[0023] Furthermore, V GND= First average voltage value *C FIX V SIG= The voltage value after the second average *C FIX .

[0024] Further, step 3 specifically includes: for the same channel, perform 12 consecutive acquisitions, put the code values ​​of the 12 acquisitions into different registers, sort them using a sorting algorithm, remove the 4 largest and smallest values, and then calculate the average of the remaining 8 results to obtain the final average value.

[0025] Furthermore, in step 2, for each switch, at least one path is grounded, and the others are connected to signals.

[0026] The advantages of this invention are: the high-precision analog signal acquisition interface calibration method provided by this invention improves the accuracy of the analog signal acquisition interface by using multiple measurement averaging calibration method, ground level calibration method, full amplitude level calibration method, and comprehensively applying the three calibration methods. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a high-precision analog quantity acquisition interface calibration method according to the present invention;

[0028] Figure 2 This is a circuit diagram of a multi-channel high-precision analog signal acquisition interface. Detailed Implementation

[0029] This invention proposes a high-precision analog quantity acquisition interface calibration method, which can significantly improve the acquisition accuracy of analog quantity interfaces and enhance the accuracy of analog quantity acquisition interfaces in airborne systems.

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 2 The multi-channel analog signal acquisition interface includes a multiplexer, a differential amplifier circuit, an A / D converter circuit, and a controller circuit. Each multiplexer has a dedicated channel for connecting to analog ground. When switch 1 is activated and connected to one end of the differential amplifier circuit, the other end of the differential amplifier circuit is connected to the analog ground channel on switch 2, thus achieving differential acquisition.

[0032] like Figure 1 As shown, a high-precision analog signal acquisition interface calibration method is applied to a multi-channel analog signal acquisition interface, and includes the following steps:

[0033] Step 1 uses the full-amplitude level calibration method to calculate the gain coefficient of the corrected A / D converter and eliminate the gain error of the analog-to-digital converter.

[0034] Step 2: Calculate the voltage value of each channel of each switch and eliminate the bias voltage on the acquisition circuit;

[0035] Step 3 employs a multiple measurement averaging calibration method. Multiple measurements are collected for each channel of each switch, and the maximum and minimum values ​​of the collected voltage values ​​are removed before averaging to obtain the average voltage value for each channel of each switch, thus eliminating errors caused by random noise.

[0036] Step 4 combines steps 1, 2, and 3 to complete the calibration of the high-precision analog interface.

[0037] 1. The full-amplitude level calibration method is used to eliminate the gain error of the analog-to-digital converter, specifically including the following steps:

[0038] Step 1.1 Provide a high-precision reference voltage source Vref that is close to the full-amplitude level of the A / D conversion device;

[0039] Step 1.2 Connect the reference voltage source Vref to the analog input terminal of the A / D converter;

[0040] Step 1.3 The A / D converter acquires the code value corresponding to Vref as Cref, and consults the A / D converter manual to obtain the theoretical code value corresponding to Vref as Ct;

[0041] Step 1.4 Calculate the gain coefficient of the corresponding device after correction: C FIX =Ct / Cref.

[0042] 2. Connect the analog ground to one of the paths of each multiplexer, and connect the signals to be acquired to the other paths of each multiplexer to obtain the voltage values ​​of each channel of each switch. The closing control of the multiplexers is implemented by FPGA.

[0043] 3. The error caused by random noise is eliminated by using the multiple measurement averaging calibration method. When ADC acquisition is performed on any channel, under the premise of sufficient conversion time, multiple conversions are performed, and a certain proportion of the maximum and minimum values ​​are removed from the conversion results. Then, the average value is calculated to achieve the multiple measurement averaging calibration method.

[0044] For each channel of each switch, multiple data acquisitions are performed, and the maximum and minimum values ​​of the acquired voltage values ​​are removed before averaging to obtain the average voltage value for each channel of each switch.

[0045] For example, for the same channel, 12 consecutive acquisitions are performed, and the code values ​​of the 12 acquisitions are placed into different registers. The FPGA uses a sorting algorithm to sort them, removes the 4 largest and smallest values, and then uses the FPGA to directly calculate the average value of the remaining 8 results from the values ​​of these 8 registers. The processor then converts these code values ​​into voltage values ​​according to the formula in the A / D converter manual.

[0046] 4. The calibration of the high-precision analog interface is completed by comprehensively applying the calibration methods in steps 1, 2, and 3, specifically including the following steps:

[0047] Step 4.1 Using C FIX Calculate the corresponding voltage value V based on the first average voltage value. GND ;

[0048] The first averaged voltage value is the voltage value obtained when the switch is switched to ground;

[0049] Step 4.2 Using C FIX Calculate the corresponding voltage value V after averaging the second voltage value. SIG ;

[0050] The second averaged voltage value is the voltage value obtained when the switch is switched to the signal;

[0051] Step 4.3V SIG Subtract V GND This is the final calibrated collected value.

[0052] V GND= First average voltage value *C FIX V SIG= The voltage value after the second average *C FIX .

Claims

1. A high-precision multi-channel analog signal acquisition interface calibration method, characterized in that, Includes the following steps: Step 1 calculates the gain coefficient of the corrected A / D converter using the full-amplitude level calibration method. Specifically: Step 1.1 Provide a high-precision reference voltage source Vref at the full-amplitude level of the A / D converter; Step 1.2 Connect the reference voltage source Vref to the analog input terminal of the A / D converter; Step 1.3 The A / D converter acquires the code value corresponding to Vref as Cref, and consults the A / D converter manual to obtain the theoretical code value Ct corresponding to Vref; Step 1.4 Calculate the gain coefficient of the corresponding device after correction: C FIX =Ct / Cref; Step 2 calculates the voltage value of each channel of each switch. Specifically, the analog ground is connected to one channel of each multiplexer, and the signal to be collected is connected to the other channels of each multiplexer to obtain the voltage value of each channel of each switch. Step 3 employs a multiple measurement averaging calibration method. Multiple acquisitions are performed on each channel of each switch, and the maximum and minimum values ​​of the acquired code values ​​are removed before averaging to obtain the average voltage value corresponding to each channel of each switch. Specifically, when performing ADC acquisition on any channel, under the premise of sufficient conversion time, multiple conversions are performed, and a certain proportion of the maximum and minimum values ​​are removed from the conversion results before averaging to achieve the multiple measurement averaging calibration method. Step 4 combines the gain coefficient from Step 1 and the averaged voltage value from Step 3 to calculate the final calibrated acquisition value, completing the calibration of the high-precision analog interface. Specifically: Step 4.1 uses C... FIX The corrected voltage value V is calculated based on the first averaged voltage value. GND The first averaged voltage value is the voltage value obtained when the switch is switched to ground; step 4.2 uses C FIX Calculate the corrected voltage value V corresponding to the second averaged voltage value. SIG Wherein, the second averaged voltage value is the voltage value obtained when the switch is switched to the signal; Step 4.3 V SIG Subtract V GND This is the final calibrated acquired value, where V GND= First average voltage value *C FIX V SIG= The voltage value after the second average *C FIX .

2. The method according to claim 1, characterized in that, Step 3 specifically includes: for the same channel, perform 12 consecutive acquisitions, put the code values ​​of the 12 acquisitions into different registers, sort them using a sorting algorithm, remove the 4 largest and smallest values, and then calculate the average of the remaining 8 results to obtain the final average value.

3. The method according to claim 1, characterized in that, In step 2, for each switch, at least one path is grounded, and the others are connected to signals.

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