CN-121462091-B - AM transmitting signal modulation depth calibration method and device

Abstract

The invention discloses a method and a device for modulating depth calibration of an AM transmitting signal, which relate to the technical field of communication, and the method comprises the steps of carrying out initialization configuration on the AM transmitting link according to a control signal sent by an AM detection control link to obtain an initial AM amplitude modulation signal; the method comprises the steps of carrying out signal conversion on an initial AM amplitude modulation signal to obtain an AM envelope digital signal, carrying out initial AM carrier signal and modulation signal amplitude calibration according to the AM envelope digital signal to obtain an initial amplitude calibration result, generating a control signal of an AM transmitting link, traversing the working frequency range of the AM transmitting link according to the control signal of the AM transmitting link, and executing S2 on a frequency point by frequency point basis to finish AM modulation depth calibration. The invention can ensure that the modulation depth of the AM transmitting signal meets the corresponding standard requirement, thereby improving the transmission quality and the power utilization rate of the AM transmitting signal and ensuring the signal transmission efficiency.

Inventors

• LIN ZIXIANG
• XI LIJUN
• CHEN ZHENZHEN
• PENG QIONGYOU
• CHEN LING
• WANG SHOUDAO

Assignees

• 中航航空电子有限公司

Dates

Publication Date

20260508

Application Date

20260106

Claims (7)

1. 1. A method for calibrating modulation depth of an AM transmission signal, the method comprising: S1, carrying out initialization configuration on an AM transmitting link according to a control signal sent by an AM detection control link to obtain an initial AM amplitude modulation signal; s2, performing signal conversion on the initial AM amplitude modulation signal to obtain an AM envelope digital signal, and performing initial AM carrier signal and modulation signal amplitude calibration according to the AM envelope digital signal to obtain an initial amplitude calibration result; the step S2 comprises the following steps: S21, performing coupling operation on an initial AM amplitude modulation signal, acquiring an AM envelope signal by using a detector based on a coupling operation result, and performing signal conversion on the AM envelope signal to obtain an AM envelope digital signal; S22, performing digital downsampling and filtering processing on the AM envelope digital signal to obtain carrier signal amplitude voltage, performing AM transmitting power detection on the carrier signal amplitude voltage, and performing primary AM carrier signal amplitude calibration based on the detection result to obtain an interaction signal; the S22 includes: S221, performing digital downsampling on the AM envelope digital signal to obtain a downsampled AM envelope digital signal, and performing filtering processing on the downsampled AM envelope digital signal by using a digital low-pass filter to obtain carrier signal amplitude voltage; S222, initializing AM transmitting power detection times, setting AGC control gain during AM transmitting power detection according to the detection times, and carrying out AM transmitting power detection on carrier signal amplitude voltage to obtain a detection result; s223, calculating a power difference value according to the detection result, carrying out power fluctuation judgment on the power difference value, and carrying out primary AM carrier signal amplitude calibration based on the power fluctuation judgment result to obtain an interaction signal; S23, carrying out AM modulation depth detection on the AM envelope digital signal based on the interaction signal to obtain an AM modulation depth, and carrying out primary AM modulation signal amplitude calibration according to the AM modulation depth to obtain a primary AM modulation signal amplitude calibration result; The S23 includes: s231, setting AM modulation depth detection times and DAC output gain adjustment times based on the interaction signals; s232, setting the regulated DAC output gain according to the DAC output gain regulation times, and setting the digital potentiometer gear during AM modulation depth detection according to the AM modulation depth detection times; s233, carrying out AM modulation depth detection on the AM envelope digital signal to obtain AM modulation depth, calculating a modulation depth difference value according to the AM modulation depth, and carrying out modulation depth fluctuation judgment on the modulation depth difference value; S234, performing primary AM modulation signal amplitude calibration based on the modulation depth fluctuation judgment result to obtain a primary AM modulation signal amplitude calibration result; And S3, generating a control signal of the AM transmitting link based on the initial amplitude calibration result, traversing the working frequency range of the AM transmitting link according to the control signal of the AM transmitting link, and executing S2 on a frequency point-by-frequency point basis to finish AM modulation depth calibration.
2. 2. The method of claim 1, wherein the control signals sent by the AM detection control link include a carrier frequency control signal, a frequency hopping filter segment code control signal, a digital potentiometer shift control signal, a digital to analog converter gain control signal, and an automatic gain control circuit gain control signal.
3. 3. The method for calibrating the modulation depth of an AM transmission signal according to claim 1, wherein the performing the preliminary AM carrier signal amplitude calibration based on the power fluctuation determination result includes: If the power fluctuation judging result shows that the power difference meets the power fluctuation requirement, storing the setting parameters of the AGC control gain into a storage medium to finish primary carrier signal amplitude calibration and obtain an interaction signal; If the power fluctuation judging result is that the power difference value does not meet the power fluctuation requirement, judging whether the AM transmitting power detecting times is larger than or equal to the maximum value of the AM transmitting power detecting times; if the number of times of AM transmitting power detection is greater than or equal to the maximum value of the number of times of AM transmitting power detection, setting parameters of AGC control gain are stored in a storage medium, and preliminary carrier signal amplitude calibration is completed to obtain an interaction signal; if the AM transmitting power detection times is smaller than the maximum value of the AM transmitting power detection times, updating the AGC control gain by using a gradient descent method to obtain the updated AGC control gain; performing dynamic range judgment on the updated AGC control gain, and adjusting the updated AGC control gain according to a dynamic range judgment result to obtain an adjusted AGC control gain; After the AGC control gain is updated and adjusted, the AM transmitting power detection times are updated, and the power fluctuation judgment and the AGC control gain updating processing are repeatedly carried out to obtain the final AGC control gain; And storing the final setting parameters of the AGC control gain into a storage medium to finish primary carrier signal amplitude calibration and obtain an interaction signal.
4. 4. The method for calibrating the modulation depth of an AM transmission signal according to claim 1, wherein the performing the preliminary AM modulation signal amplitude calibration based on the modulation depth fluctuation determination result to obtain the preliminary AM modulation signal amplitude calibration result comprises: if the modulation depth fluctuation judging result shows that the modulation depth meets the modulation depth fluctuation requirement, storing the adjusted DAC output gain and the setting parameters of the digital potentiometer gear into a storage medium to finish primary modulation signal amplitude calibration, and obtaining a primary AM modulation signal amplitude calibration result; If the modulation depth fluctuation judging result is that the modulation depth does not meet the modulation depth fluctuation requirement, judging whether the AM modulation depth detection times are larger than or equal to the maximum value of the AM modulation depth detection times; if the AM modulation depth detection times are smaller than the maximum value of the AM modulation depth detection times, updating the digital potentiometer gear by using a gradient descent method, and judging and adjusting the range of the updated digital potentiometer gear to obtain an adjusted digital potentiometer gear; if the DAC output gain is smaller than or equal to the minimum value of the DAC output gain, setting parameters of the DAC output gain and a digital potentiometer gear are stored in a storage medium, and preliminary modulation signal amplitude calibration is completed, so that a preliminary AM modulation signal amplitude calibration result is obtained; If the regulated DAC output gain is larger than the minimum value of the DAC output gain, subtracting the DAC gain regulation step from the regulated DAC output gain, and judging and regulating the range of the updated DAC output gain to obtain the regulated DAC output gain; And repeatedly executing modulation depth fluctuation judgment and digital potentiometer gear and DAC output gain updating processing according to the adjusted digital potentiometer gear and the adjusted DAC output gain, and completing primary modulation signal amplitude calibration to obtain a primary AM modulation signal amplitude calibration result.
5. 5. An AM transmission signal modulation depth calibration device for implementing the AM transmission signal modulation depth calibration method according to any one of claims 1 to 4, wherein the AM transmission signal modulation depth calibration device comprises an AM transmission link and an AM detection control link; the AM transmitting link is used for receiving the control signal output by the AM detection control link and outputting an AM amplitude modulation signal; the AM detection control link is used for generating a control signal for controlling the AM transmitting link to finish modulation depth calibration; one end of the AM transmitting link is connected with one end of the AM detection control link.
6. 6. The device according to claim 5, wherein the AM transmitting link comprises a frequency hopping filter, a power amplifier, an automatic gain control circuit, an automatic level control circuit, a digital potentiometer, a digital-to-analog converter, and a radio frequency signal source; the digital-to-analog converter is used for receiving the digital-to-analog converter gain control signal and the calibration sequence signal and outputting a first modulation signal; the digital potentiometer is used for receiving the digital potentiometer gear control signal and the first modulation signal and outputting a second modulation signal; The radio frequency signal source is used for receiving the carrier frequency control signal and outputting a carrier signal; the automatic level control circuit is used for receiving the carrier signal and the AM envelope signal after the filtering processing to finish AM modulation; The automatic gain control circuit is used for receiving the gain control signal of the automatic gain control circuit and amplifying the AM amplitude modulation signal output by the automatic level control circuit; the power amplifier is used for amplifying the AM amplitude modulation signal output by the automatic gain control circuit; the frequency hopping filter is used for receiving the frequency hopping filter segment code control signal and filtering an external interference signal of the AM amplitude modulation signal output by the power amplifier; the first pin of the frequency hopping filter is connected with one end of the power amplifier, the other end of the power amplifier is connected with the first pin of the automatic gain control circuit, the second pin of the automatic gain control circuit is connected with the first pin of the automatic level control circuit, the second pin of the automatic level control circuit is connected with one end of the radio frequency signal source, the third pin of the automatic level control circuit is connected with the first pin of the digital potentiometer, and the second pin of the digital potentiometer is connected with the first pin of the digital-analog converter.
7. 7. The AM transmission signal modulation depth calibration apparatus according to claim 6, wherein said AM detection control link comprises a directional coupler, a detector, a low pass filter, an analog-to-digital converter, a control processor, and a storage medium; the directional coupler is used for coupling the AM amplitude modulation signal and outputting the coupled amplitude modulation signal; the detector is used for receiving the coupled amplitude modulation signals and outputting two paths of AM envelope signals; the low-pass filter is used for filtering the AM envelope signal and inputting the AM envelope signal into the automatic level control circuit; the analog-to-digital converter is used for converting the AM envelope signal into an AM envelope digital signal; The control processor is used for carrying out AM modulation depth calibration on the received AM envelope digital signal and outputting a carrier frequency control signal, a frequency hopping filter segment code control signal, a digital potentiometer gear control signal, a digital-to-analog converter gain control signal, a calibration sequence signal, a storage medium control signal and an automatic gain control circuit gain control signal; The storage medium is used for receiving a storage medium control signal and storing control parameters of AM modulation depth calibration; One end of the directional coupler is connected with a second pin of the frequency hopping filter, the other end of the directional coupler is connected with one end of the detector, the other end of the detector is connected with one end of the low-pass filter and one end of the analog-to-digital converter respectively, the other end of the low-pass filter is connected with a fourth pin of the automatic level control circuit, the other end of the analog-to-digital converter is connected with a first pin of the control processor, a second pin, a third pin and a fourth pin of the control processor are connected with one end of the storage medium respectively, a fifth pin of the control processor is connected with a third pin of the digital potentiometer, a sixth pin of the control processor is connected with a second pin of the digital-to-analog converter, a seventh pin of the control processor is connected with a third pin of the digital-to-analog converter, an eighth pin of the control processor is connected with the other end of the radio frequency signal source, a ninth pin of the control processor is connected with a third pin of the frequency hopping filter, and a tenth pin of the control processor is connected with the automatic gain control circuit.

Description

AM transmitting signal modulation depth calibration method and device Technical Field The invention relates to the technical field of communication, in particular to an AM transmitting signal modulation depth calibration method and device. Background AM modulation is widely used in broadcasting to transmit voice signals by modulating the voice signals to the amplitude of a carrier wave and finally transmitting the voice signals in the form of electromagnetic waves to a radio or other receiving devices. The modulation depth represents the modulation degree of the voice signal to the carrier amplitude, the modulation depth determines the quality of the voice signal and the power utilization rate of the transmitting equipment, when the modulation depth is too large, the voice signal becomes distorted or truncated, when the modulation depth is too small, the anti-interference capability is weakened, the transmitting power of the equipment cannot be effectively utilized, and the signal transmission efficiency is reduced, so that the modulation depth calibration for the AM transmitting signal is very important. The modulation depth of Amplitude Modulation (AM) is the ratio of the amplitude of the modulated signal to the amplitude of the carrier signal in an amplitude modulated signal. The modulation depth is determined by both the carrier signal amplitude and the modulation signal amplitude, so that the modulation depth calibration is performed by two steps of carrier amplitude calibration and modulation signal amplitude calibration. There are few relevant materials for AM transmit signal modulation depth calibration, and for the state of the art of AM transmit signal modulation depth calibration, a brief description of both carrier signal amplitude (i.e., transmit power) calibration and modulation signal amplitude calibration of an AM transmit signal is as follows: 1. For carrier signal amplitude calibration, an external calibration method is often used for AM transmission signal carrier amplitude (i.e. transmission power) calibration, for example, patent CN202422115851 proposes an AM transmission power calibration method and apparatus, whose calibration schematic block diagram is shown in fig. 8. The method measures the AM signal power of the transmitting port of the AM transmitter and the input port of the power amplifying unit by using a power meter and a spectrum analyzer, and feeds back the measured power value to a computer, and the computer outputs a control signal by comparing the measured power value with a target power value to control the output signal power of an exciting unit in the AM transmitter so as to achieve the aim of calibrating the carrier amplitude of the AM transmitting signal. 2. For the amplitude calibration of a modulation signal, the number of related materials for calibration is small, and patent CN202410024225 proposes an AM modulation depth control method, which is to calculate the broadcast signal power and the clutter power of AM audio sampling data within the bandwidth of 20 hz-20 khz and within the bandwidth of 20 khz-60 khz through an FFT algorithm, then calculate the target power ratio of the broadcast signal power and the clutter power, and match the target modulation degree corresponding to the target power ratio from a preset modulation degree lookup table, and if the target modulation degree exceeds the first modulation degree threshold, reduce the amplitude of the input audio signal corresponding to the AM audio sampling data. In summary, the existing AM transmit signal modulation depth calibration technique has the following drawbacks: in the AM carrier signal amplitude (namely, transmitting power) calibration method, test instruments such as a spectrum analyzer, a power meter and the like are needed, but the test instruments such as the spectrum analyzer, the power meter and the like are high in price, and the calibration system is high in construction cost and is not suitable for large-scale deployment of production lines. The related technology of AM modulation signal amplitude calibration is less, and the AM modulation depth control method proposed by patent CN202410024225 uses 65536 point FFT algorithm to calculate the power of the AM signal, however 65536 point FFT calculation time is longer, and the bandwidth of calculated power is wider, the noise power is larger, so that the accuracy of the calculated power value is poorer, and the control accuracy of the AM modulation depth is affected. For the problems in the related art, no effective solution has been proposed at present. Disclosure of Invention Aiming at the problems in the related art, the invention provides an AM transmitting signal modulation depth calibration method and device, which are used for overcoming the technical problems existing in the prior related art. For this purpose, the invention adopts the following specific technical scheme: According to an aspect of the present invention, there is pro