AM emission signal modulation depth calibration method and device

Abstract

The invention discloses an AM transmitting signal modulation depth calibration method and device, and relates to the technical field of communication, and the method comprises the steps: carrying out the initialization configuration of an AM transmitting link according to a control signal transmitted by an AM detection control link, and obtaining an initial AM signal; performing signal conversion on the initial AM amplitude modulation signal to obtain an AM envelope digital signal, and performing preliminary amplitude calibration on an AM carrier signal and a modulation signal according to the AM envelope digital signal to obtain a preliminary amplitude calibration result; and S2, generating a control signal of the AM transmitting link, traversing the working frequency band range of the AM transmitting link according to the control signal of the AM transmitting link, and executing S2 frequency point by frequency point to complete AM modulation depth calibration. According to the invention, the modulation depth of the AM transmitting signal can meet the corresponding standard requirement, so that the transmission quality and the power utilization rate of the AM transmitting signal are improved, and the signal transmission efficiency is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to a method and device for calibrating modulation depth of AM transmitting signal. BACKGROUND

[0002] AM modulation mode is widely used in broadcasting for transmitting voice signal, which is completed by modulating voice signal to the amplitude of carrier wave, and finally transmitted in the form of electromagnetic wave to realize the transmission of voice signal to radio or other receiving devices. Modulation depth represents the degree of modulation of voice signal to carrier amplitude, and the size of modulation depth determines the quality of voice signal and the power utilization rate of transmitting device. When the modulation depth is too large, the voice signal will become distorted or clipped, and when the modulation depth is too small, the anti-interference ability is weakened, the device transmitting power cannot be effectively utilized, and the signal transmission efficiency is reduced, so it is very important to calibrate the modulation depth of AM transmitting signal.

[0003] The modulation depth of amplitude modulation (AM) is the ratio of the amplitude of the modulating signal to the amplitude of the carrier signal in the amplitude modulation signal. The modulation depth is determined by the carrier signal amplitude and the modulating signal amplitude, so the modulation depth calibration needs to perform carrier amplitude calibration and modulating signal amplitude calibration. There are few related materials about the calibration of modulation depth of AM transmitting signal, and the current technical status of the calibration of modulation depth of AM transmitting signal is briefly described as follows from the aspects of carrier signal amplitude (i.e. transmitting power) calibration and modulating signal amplitude calibration of AM transmitting signal:

[0004] I. For carrier signal amplitude calibration, the AM transmitting signal carrier amplitude (i.e. transmitting power) calibration mostly adopts external calibration method. For example, patent CN202422115851 proposes an AM transmitting power calibration method and device, and the calibration principle block diagram is shown in Figure 8 The method measures the AM signal power of the transmitting port of AM transmitter and the input port of power amplifier unit by using power meter and spectrum analyzer, and feeds back the measured power value to computer. The computer compares the measured power value with the target power value, and outputs control signal to control the output signal power of excitation unit in AM transmitter, so as to achieve the purpose of calibrating the carrier amplitude of AM transmitting signal.

[0005] II. For the modulation signal amplitude calibration, the related materials for calibration are less, and the patent CN202410024225 proposes an AM modulation depth control method. The control method is to calculate the broadcast signal power in the 20Hz~20kHz bandwidth and the noise power in the 20kHz~60kHz bandwidth of the AM audio sampling data through the FFT algorithm; then calculate the target power ratio of the broadcast signal power and the noise power, and match the target modulation degree corresponding to the target power ratio from the preset modulation degree lookup table. If the target modulation degree exceeds the first modulation degree threshold, the amplitude of the input audio signal corresponding to the AM audio sampling data is reduced.

[0006] In summary, the existing AM transmission signal modulation depth calibration technology has the following shortcomings:

[0007] The AM carrier signal amplitude (i.e. transmission power) calibration method needs to use spectrum analyzers, power meters and other test instruments, and the spectrum analyzers, power meters and other test instruments are expensive, the calibration system has high construction cost, and is not suitable for large-scale deployment of production lines.

[0008] The AM modulation signal amplitude calibration related technology is less, and the AM modulation depth control method proposed by the patent CN202410024225 uses a 65536-point FFT algorithm to calculate the power of the AM signal. However, the 65536-point FFT calculation time is long, and the bandwidth for calculating the power is wide, and the noise power is large, so that the accuracy of the calculated power value is poor, which affects the control accuracy of the AM modulation depth.

[0009] In view of the problems in the related art, no effective solution has been proposed so far. SUMMARY

[0010] In view of the problems in the related art, the present application proposes an AM transmission signal modulation depth calibration method and device to overcome the above technical problems existing in the prior art.

[0011] To this end, the specific technical solutions adopted by the present application are as follows:

[0012] According to one aspect of the present application, an AM transmission signal modulation depth calibration method is provided, which comprises the following steps:

[0013] S1, initializing and configuring the AM transmission link according to the control signal sent by the AM detection control link to obtain an initial AM amplitude modulation signal;

[0014] S2, converting the initial AM amplitude modulation signal to obtain an AM envelope digital signal, and performing preliminary AM carrier signal and modulation signal amplitude calibration according to the AM envelope digital signal to obtain a preliminary amplitude calibration result;

[0015] S3, generating a control signal of the AM transmitting link based on the preliminary amplitude calibration result, traversing a frequency range of the AM transmitting link according to the control signal of the AM transmitting link, and performing S2 to complete the AM modulation depth calibration point by point.

[0016] Further, the control signal sent by the AM detection control link includes a carrier frequency control signal, a frequency hopping filter section code control signal, a digital potentiometer gear control signal, a digital-to-analog converter gain control signal, and an automatic gain control circuit gain control signal.

[0017] Further, the initial AM amplitude modulation signal is converted to obtain an AM envelope digital signal, and the preliminary AM carrier signal and the modulation signal amplitude are calibrated based on the AM envelope digital signal to obtain the preliminary amplitude calibration result, including:

[0018] S21, coupling the initial AM amplitude modulation signal, and based on the coupling operation result, using a detector to obtain an AM envelope signal, and converting the AM envelope signal to obtain an AM envelope digital signal;

[0019] S22, digitally down-sampling and filtering the AM envelope digital signal to obtain a carrier signal amplitude voltage, and detecting the AM transmitting power of the carrier signal amplitude voltage, and based on the detection result, performing preliminary AM carrier signal amplitude calibration to obtain an interaction signal;

[0020] S23, detecting the AM modulation depth of the AM envelope digital signal based on the interaction signal to obtain the AM modulation depth, and performing preliminary AM modulation signal amplitude calibration according to the AM modulation depth to obtain the preliminary AM modulation signal amplitude calibration result.

[0021] Further, the AM envelope digital signal is digitally down-sampled and filtered to obtain a carrier signal amplitude voltage, and the AM transmitting power of the carrier signal amplitude voltage is detected, and based on the detection result, preliminary AM carrier signal amplitude calibration is performed to obtain an interaction signal, including:

[0022] S221, digitally down-sampling the AM envelope digital signal to obtain a down-sampled AM envelope digital signal, and filtering the down-sampled AM envelope digital signal using a digital low-pass filter to obtain a carrier signal amplitude voltage;

[0023] S222, initializing the number of AM transmitting power detection times, and setting the AGC control gain during AM transmitting power detection according to the detection times, detecting the AM transmitting power of the carrier signal amplitude voltage to obtain a detection result;

[0024] S223、According to the detection result, the power difference value is calculated, and the power fluctuation is judged. Based on the power fluctuation judgment result, the preliminary AM carrier signal amplitude calibration is carried out, and the interactive signal is obtained.

[0025] Further, based on the power fluctuation judgment result, the preliminary AM carrier signal amplitude calibration is carried out, and the interactive signal is obtained, including:

[0026] If the power fluctuation judgment result is that the power difference value meets the power fluctuation requirement, the setting parameters of the AGC control gain are stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0027] If the power fluctuation judgment result is that the power difference value does not meet the power fluctuation requirement, it is judged whether the AM transmitting power detection times is greater than or equal to the maximum value of the AM transmitting power detection times.

[0028] If the AM transmitting power detection times is greater than or equal to the maximum value of the AM transmitting power detection times, the setting parameters of the AGC control gain are stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0029] If the AM transmitting power detection times is less than the maximum value of the AM transmitting power detection times, the gradient descent method is used to update the AGC control gain, and the updated AGC control gain is obtained.

[0030] The updated AGC control gain is judged for dynamic range, and the updated AGC control gain is adjusted according to the dynamic range judgment result, and the adjusted AGC control gain is obtained.

[0031] After the AGC control gain is updated and adjusted, the AM transmitting power detection times is updated, and the power fluctuation judgment and the AGC control gain update process are repeated, and the final AGC control gain is obtained.

[0032] The setting parameters of the final AGC control gain are stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0033] Further, based on the interactive signal, the AM modulation depth detection is carried out on the AM envelope digital signal, the AM modulation depth is obtained, and the preliminary AM modulation signal amplitude calibration is carried out according to the AM modulation depth, and the preliminary AM modulation signal amplitude calibration result is obtained, including:

[0034] S231, based on the interactive signal, the AM modulation depth detection times and the DAC output gain adjustment times are set.

[0035] S232, set the adjusted DAC output gain according to the DAC output gain adjustment times setting, and set the digital potentiometer position when the AM modulation depth detection is performed according to the AM modulation depth detection times setting;

[0036] S233, perform AM modulation depth detection on the AM envelope digital signal to obtain the AM modulation depth, calculate the modulation depth difference value according to the AM modulation depth, and perform modulation depth fluctuation judgment on the modulation depth difference value;

[0037] S234, perform preliminary AM modulation signal amplitude calibration based on the modulation depth fluctuation judgment result to obtain the preliminary AM modulation signal amplitude calibration result.

[0038] Further, the preliminary AM modulation signal amplitude calibration based on the modulation depth fluctuation judgment result to obtain the preliminary AM modulation signal amplitude calibration result includes:

[0039] If the modulation depth fluctuation judgment result is that the modulation depth meets the modulation depth fluctuation requirement, the setting parameters of the adjusted DAC output gain and the digital potentiometer position are stored in the storage medium, the preliminary modulation signal amplitude calibration is completed, and the preliminary AM modulation signal amplitude calibration result is obtained.

[0040] If the modulation depth fluctuation judgment result is that the modulation depth does not meet the modulation depth fluctuation requirement, it is judged whether the AM modulation depth detection times is greater than or equal to the maximum value of the AM modulation depth detection times.

[0041] If the AM modulation depth detection times is less than the maximum value of the AM modulation depth detection times, the gradient descent method is used to update the digital potentiometer position, and the range judgment and adjustment are performed on the updated digital potentiometer position to obtain the adjusted digital potentiometer position.

[0042] If the AM modulation depth detection times is greater than or equal to the maximum value of the AM modulation depth detection times, it is judged whether the adjusted DAC output gain is less than or equal to the minimum value of the DAC output gain.

[0043] If the adjusted DAC output gain is less than or equal to the minimum value of the DAC output gain, the setting parameters of the adjusted DAC output gain and the digital potentiometer position are stored in the storage medium, the preliminary modulation signal amplitude calibration is completed, and the preliminary AM modulation signal amplitude calibration result is obtained.

[0044] If the adjusted DAC output gain is greater than the minimum value of the DAC output gain, the adjusted DAC output gain is subtracted by the DAC gain adjustment step, and the range judgment and adjustment are performed on the updated DAC output gain to obtain the adjusted DAC output gain.

[0045] According to the adjusted digital potentiometer position and the adjusted DAC output gain, the modulation depth fluctuation judgment and the digital potentiometer position and the DAC output gain updating process are repeatedly executed, the preliminary modulation signal amplitude calibration is completed, and a preliminary AM modulation signal amplitude calibration result is obtained.

[0046] According to another aspect of the present application, an AM transmission signal modulation depth calibration device is provided, which comprises an AM transmission link and an AM detection control link.

[0047] The AM transmission link is configured to receive the control signal output by the AM detection control link and output an AM amplitude modulation signal.

[0048] The AM detection control link is configured to generate the control signal for controlling the AM transmission link and complete the modulation depth calibration.

[0049] One end of the AM transmission link is connected to one end of the AM detection control link.

[0050] Further, the AM transmission 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.

[0051] The digital-to-analog converter is configured to receive the digital-to-analog converter gain control signal and the calibration sequence signal and output a first modulation signal.

[0052] The digital potentiometer is configured to receive the digital potentiometer position control signal and the first modulation signal and output a second modulation signal.

[0053] The radio frequency signal source is configured to receive the carrier frequency control signal and output a carrier signal.

[0054] The automatic level control circuit is configured to receive the carrier signal and the filtered AM envelope signal and complete the AM modulation.

[0055] The automatic gain control circuit is configured to receive the automatic gain control circuit gain control signal and amplify the AM amplitude modulation signal output by the automatic level control circuit.

[0056] The power amplifier is configured to amplify the AM amplitude modulation signal output by the automatic gain control circuit.

[0057] The frequency hopping filter is configured to receive the frequency hopping filter segment code control signal and filter out the external interference signal of the AM amplitude modulation signal output by the power amplifier.

[0058] 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-to-analog converter.

[0059] Further, the 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.

[0060] The directional coupler is used for coupling the AM signal and outputting the coupled AM signal.

[0061] The detector is used for receiving the coupled AM signal and outputting two-way AM envelope signals.

[0062] The low-pass filter is used for filtering the AM envelope signal and inputting the automatic level control circuit.

[0063] The analog-to-digital converter is used for converting the AM envelope signal into an AM envelope digital signal.

[0064] The control processor is used for calibrating the AM modulation depth of 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.

[0065] The storage medium is used for receiving the storage medium control signal and storing the control parameters of the AM modulation depth calibration.

[0066] One end of the directional coupler is connected with the 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 the fourth pin of the automatic level control circuit, the other end of the analog-to-digital converter is connected with the first pin of the control processor, the second pin, the third pin, and the fourth pin of the control processor are connected with one end of the storage medium, respectively, the fifth pin of the control processor is connected with the third pin of the digital potentiometer, the sixth pin of the control processor is connected with the second pin of the digital-to-analog converter, the seventh pin of the control processor is connected with the third pin of the digital-to-analog converter, the eighth pin of the control processor is connected with the other end of the radio frequency signal source, the ninth pin of the control processor is connected with the third pin of the frequency hopping filter, and the tenth pin of the control processor is connected with the third pin of the automatic gain control circuit.

[0067] The beneficial effects of the present application are:

[0068] 1、The present application makes the modulation depth of AM signal meet the corresponding standard requirements through carrier signal amplitude calibration and modulation signal amplitude calibration, thereby improving the precision of AM transmitter transmission power and modulation depth, and further improving the transmission quality and power utilization rate of AM signal, and ensuring the signal transmission efficiency.

[0069] 2、The present application uses a low-cost carrier signal amplitude and modulation signal amplitude internal calibration method, without the need for expensive instruments such as spectrum analyzers and power meters, which is suitable for large-scale deployment in production lines; and through carrier signal amplitude calibration before modulation signal amplitude calibration, the automatic level control circuit is calibrated under the premise of an accurate power reference signal, which greatly reduces the influence of AM transmission power fluctuation on AM modulation depth and improves the precision of AM modulation depth calibration.

[0070] 3、The present application uses digital downsampling and digital low-pass filter in the carrier signal amplitude calibration method, which filters out out-of-band noise and greatly reduces noise power, thereby improving the precision of AM transmission power detection; and the gradient descent method is used to optimize the AGC control gain, which improves the calibration precision of carrier signal amplitude while ensuring the optimization speed.

[0071] 4、The present application uses two-stage control of DAC output gain and digital potentiometer gear in the modulation signal amplitude calibration, which increases the total adjustment range of variables in the modulation signal amplitude calibration process, thereby improving the precision of modulation signal amplitude calibration; and the gradient descent method is used to adjust the digital potentiometer gear, which improves the calibration precision of modulation signal amplitude while ensuring the optimization speed. BRIEF DESCRIPTION OF DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0073] Figure 1 is a flow chart of an AM transmission signal modulation depth calibration method according to an embodiment of the present application;

[0074] Figure 2 is a schematic diagram of an AM transmission signal modulation depth calibration device according to an embodiment of the present application;

[0075] Figure 3 is an AM modulation depth calibration schematic diagram in an AM transmission signal modulation depth calibration method according to an embodiment of the present application;

[0076] Figure 4 is a carrier signal amplitude calibration processing schematic diagram in an AM transmitting signal modulation depth calibration method according to an embodiment of the present application;

[0077] Figure 5 is a carrier signal amplitude calibration flow chart in an AM transmitting signal modulation depth calibration method according to an embodiment of the present application;

[0078] Figure 6 is a modulation signal amplitude calibration schematic diagram in an AM transmitting signal modulation depth calibration method according to an embodiment of the present application;

[0079] Figure 7 is a modulation signal amplitude calibration flow chart in an AM transmitting signal modulation depth calibration method according to an embodiment of the present application;

[0080] Figure 8 is an AM carrier signal amplitude external calibration method principle block diagram in patent CN202422115851. DETAILED DESCRIPTION

[0081] To further explain the embodiments, the present application provides drawings which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can explain the operation principle of the embodiments in conjunction with the related description of the specification. Those skilled in the art should understand other possible implementations and advantages of the present application by referring to these contents.

[0082] According to an embodiment of the present application, an AM transmitting signal modulation depth calibration method and device are provided.

[0083] The present application will be further described in conjunction with the drawings and specific embodiments, as shown in Figure 1 According to an embodiment of the present application, an AM transmitting signal modulation depth calibration method is provided, which includes the following steps:

[0084] An AM transmitting signal modulation depth calibration method, characterized in that the method includes:

[0085] S1, initializing and configuring the AM transmitting link according to the control signal sent by the AM detection control link, to obtain an initial AM amplitude modulation signal.

[0086] Specifically, the control signal sent by the AM detection control link includes 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, and an automatic gain control circuit gain control signal.

[0087] Specifically, as Figure 2As shown, the AM transmitting signal modulation depth calibration device provided by the application is composed of an amplitude modulation (AM) transmitting link and an AM detection control link, one end of the AM transmitting link is connected with one end of the AM detection control link, wherein the AM transmitting link is composed of a frequency hopping filter, a power amplifier, an automatic gain control circuit (AGC), an automatic level control circuit (ALC), a digital potentiometer, a digital-to-analog converter (DAC) and a radio frequency signal source; the AM detection control link is composed of a directional coupler, a detector, a low-pass filter, an analog-to-digital converter (ADC), a control processor and a storage medium, wherein the control processor is composed of an AM modulation depth calibration processing module and a control module, the AM modulation depth calibration processing module is composed of a modulation signal amplitude calibration processing module and a carrier signal amplitude calibration processing module, and the modulation signal amplitude calibration processing module is connected with the carrier signal amplitude calibration processing module.

[0088] In the application, the AM transmitting link and the AM detection control link constitute a closed loop of AM transmitting signal modulation depth calibration, the radio frequency signal source in the AM transmitting link outputs a carrier signal with stable power but small power, the DAC and the digital potentiometer output a modulation signal, the ALC module takes the signal output by the low-pass filter as a power reference signal, completes AM modulation and outputs an AM amplitude modulation signal with small power, the AM amplitude modulation signal with small power is amplified by the AGC and the power amplifier and then input to the frequency hopping filter, and the AM amplitude modulation signal with corresponding power is output after filtering out the out-of-band interference signal. The AM amplitude modulation signal transmitted by the AM transmitting link is coupled back to the AM detection control link by the directional coupler, the coupled back AM amplitude modulation signal outputs two same AM envelope signals by the detector, one AM envelope signal is input to the ALC module as a power reference signal after being filtered by the low-pass filter, and the power of the AM amplitude modulation signal output by the ALC module is adjusted; the other AM envelope signal is converted into an AM envelope digital signal by the ADC module and then input to the AM modulation depth calibration processing module in the control processor, the AM modulation depth calibration processing module in the control processor processes the input AM envelope digital signal, outputs control signals of the AGC, the digital potentiometer and the DAC, controls and compensates the AGC, the digital potentiometer and the DAC, and stores the control parameters of the AGC, the digital potentiometer and the DAC in the storage medium, thereby completing the modulation depth calibration of the AM transmitting signal. In addition, the control processor further contains a control module, which sends a carrier frequency control signal to control the working frequency of the carrier signal output by the radio frequency signal source, sends a frequency hopping filter segment code control signal to control the working frequency segment of the frequency hopping filter, and outputs a calibration sequence signal to the DAC to make the DAC output a sine signal with a corresponding frequency.

[0089] Specifically, as shown in Figure 3As shown, it is the specific process of AM modulation depth calibration; wherein, the initialization configuration (i.e. initialization setting) is that through the control of the control processor in the control processing module, the carrier frequency control signal is sent to set the initial working frequency of the carrier signal output by the radio frequency signal source, the frequency band range of the passband of the frequency hopping filter is made to contain the working frequency of the carrier signal output by the radio frequency signal source by sending the frequency hopping filter segment code control signal, and the sine waveform calibration sequence signal is output, the frequency range of which is 20Hz~10.24kHz, and the typical frequency 1kHz is selected by the application; the digital potentiometer gear control signal is sent by the AM modulation depth calibration processing module to set the gear of the digital potentiometer to the middle gear in the adjustment range, the DAC gain control signal is sent to set the output gain of the DAC to the maximum gain, and the AGC gain control signal is sent to set the gain of the AGC to the middle gain in the dynamic range.

[0090] S2, signal conversion is performed on the initial AM amplitude modulation signal to obtain an AM envelope digital signal, and preliminary AM carrier signal and modulation signal amplitude calibration is performed according to the AM envelope digital signal to obtain a preliminary amplitude calibration result.

[0091] Specifically, signal conversion is performed on the initial AM amplitude modulation signal to obtain an AM envelope digital signal, and preliminary AM carrier signal and modulation signal amplitude calibration is performed according to the AM envelope digital signal to obtain a preliminary amplitude calibration result, including:

[0092] S21, coupling operation is performed on the initial AM amplitude modulation signal, and based on the coupling operation result, an AM envelope signal is obtained by using a detector, and signal conversion is performed on the AM envelope signal to obtain an AM envelope digital signal;

[0093] S22, digital downsampling and filtering processing are performed on the AM envelope digital signal to obtain a carrier signal amplitude voltage, and AM transmission power detection is performed on the carrier signal amplitude voltage, and based on the detection result, preliminary AM carrier signal amplitude calibration is performed to obtain an interactive signal.

[0094] Specifically, digital downsampling and filtering processing are performed on the AM envelope digital signal to obtain a carrier signal amplitude voltage, and AM transmission power detection is performed on the carrier signal amplitude voltage, and based on the detection result, preliminary AM carrier signal amplitude calibration is performed to obtain an interactive signal, including:

[0095] S221, digital downsampling is performed on the AM envelope digital signal to obtain a downsampled AM envelope digital signal, and filtering processing is performed on the downsampled AM envelope digital signal by using a digital low-pass filter to obtain a carrier signal amplitude voltage;

[0096] S222, initialize the AM transmit power detection times, set the AGC control gain for the AM transmit power detection according to the detection times, perform the AM transmit power detection on the carrier signal amplitude voltage, and obtain a detection result;

[0097] S223, calculate a power difference value according to the detection result, perform power fluctuation judgment on the power difference value, perform preliminary AM carrier signal amplitude calibration based on the power fluctuation judgment result, and obtain an interactive signal.

[0098] Specifically, the preliminary AM carrier signal amplitude calibration based on the power fluctuation judgment result to obtain the interactive signal includes:

[0099] If the power fluctuation judgment result is that the power difference value meets the power fluctuation requirement, the setting parameter of the AGC control gain is stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0100] If the power fluctuation judgment result is that the power difference value does not meet the power fluctuation requirement, it is judged whether the AM transmit power detection times is greater than or equal to the maximum value of the AM transmit power detection times.

[0101] If the AM transmit power detection times is greater than or equal to the maximum value of the AM transmit power detection times, the setting parameter of the AGC control gain is stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0102] If the AM transmit power detection times is less than the maximum value of the AM transmit power detection times, the AGC control gain is updated by using the gradient descent method, and an updated AGC control gain is obtained.

[0103] The updated AGC control gain is subjected to dynamic range judgment, the updated AGC control gain is adjusted according to the dynamic range judgment result, and an adjusted AGC control gain is obtained.

[0104] After the AGC control gain is updated and adjusted, the AM transmit power detection times is updated, and the power fluctuation judgment and the AGC control gain updating process are repeated to obtain a final AGC control gain.

[0105] The setting parameter of the final AGC control gain is stored in the storage medium, the preliminary carrier signal amplitude calibration is completed, and the interactive signal is obtained.

[0106] Specifically, after initialization, the AM transmit link transmits an AM amplitude modulated signal. The AM detection and control link couples back the AM amplitude modulated signal transmitted by the AM transmit link, outputting an AM envelope signal through a detector. This AM envelope signal is then input to an ADC for sampling, quantization, and encoding, converting it into an AM envelope digital signal. This signal is then input to the AM modulation depth calibration processing module in the control processor. The module is divided into two paths: one for carrier signal amplitude calibration and the other for modulation signal amplitude calibration. A schematic diagram of the carrier signal amplitude calibration processing in the AM modulation depth calibration processing module is shown below. Figure 4 As shown, Figure 4 The AM modulation depth calibration processing module includes a carrier signal amplitude calibration processing module, which includes a digital downsampling module, a digital low-pass filter, and a carrier amplitude calibration module. The digital downsampling module receives the AM envelope digital signal, one end of which is connected to one end of the digital low-pass filter, and the other end of the digital low-pass filter is connected to one end of the carrier amplitude calibration module. The carrier amplitude calibration module outputs a storage medium control signal, an interactive signal, and an AGC gain control signal.

[0107] Typically, the sampling clock frequency of an ADC is much higher than the frequency of the AM envelope signal. To save hardware resources for the control processor and reduce the redundancy of the AM envelope digital signal data, the AM envelope digital signal is first digitally downsampled after input to the carrier signal amplitude calibration processing module, reducing the sampling frequency of the AM envelope signal to 5 to 8 times the AM envelope signal frequency. The downsampled AM envelope digital signal is then input to a digital low-pass filter. The passband cutoff frequency of the digital low-pass filter is much lower than the frequency of the AM envelope signal. After filtering out the AM envelope signal, the digital low-pass filter outputs a carrier signal amplitude voltage U to the carrier signal amplitude calibration module. The carrier signal amplitude calibration module uses voltage U to detect the AM transmit power. Based on the detected AM transmit power, it sends an AGC gain control signal to control the AGC gain until the AM transmit power meets the target power requirement. At this point, the carrier signal amplitude calibration module stops AGC gain control and sends a storage medium control signal to store the AGC gain control parameters in the storage medium, completing the carrier signal amplitude calibration. The carrier signal amplitude calibration flowchart is shown below. Figure 5 As shown, the detailed steps are as follows:

[0108] Step 2.1 sets the AM transmit power detection count i to an initial value of i=1.

[0109] Step 2.2 involves sending the AGC gain control signal to set the AGC gain G during the i-th AM transmit power detection. i When i=1, the gain of AGC is set to the intermediate gain within the dynamic range.

[0110] Step 2.3 is to use the carrier signal amplitude voltage U output by the digital filter.m Perform the i-th AM transmit power detection and calculate the i-th AM transmit power P. i .

[0111] The formula for calculating AM transmit power is:

[0112] ;

[0113] In the formula, U m is the first n voltages received by the carrier amplitude calibration module after the start of the i-th AM transmit power calculation, in V; n is the total number of voltages used for power calculation; and At is the total link attenuation of the directional coupler and detector in the AM detection link, in dB.

[0114] Step 2.4 is to calculate the AM transmission power P of the i-th transmission. i With target power P opt The difference ∆P i =P i -P opt .

[0115] Step 2.5 is to determine the power difference ∆P obtained in the i-th iteration. i If the power fluctuation requirement is met, then send the storage medium control signal to increase the AGC gain G for the i-th iteration. i The settings parameters are stored in the storage medium to complete the carrier signal amplitude calibration and maintain the AGC gain at G. i The carrier signal amplitude calibration module sends an interactive signal to the modulation signal amplitude calibration module to inform the modulation signal amplitude calibration module to start the modulation signal amplitude calibration function; if the power fluctuation requirements are not met, proceed to step 2.6.

[0116] Step 2.6 is to determine whether the number of AM transmit power detections i is less than the maximum value i of the number of AM transmit power detections. max , if i max Then the cached AM detection power P of the i-th time i and AGC control gain G i Then proceed to steps 2.7~2.9; if i≥i max Then, the storage medium control signal will be sent to increase the AGC gain G of the i-th iteration. i The settings parameters are stored in the storage medium to complete the carrier signal amplitude calibration and maintain the AGC gain at G. i The carrier signal amplitude calibration module sends an interactive signal to the modulation signal amplitude calibration module, informing the modulation signal amplitude calibration module to start the modulation signal amplitude calibration function.

[0117] Step 2.7 involves using the gradient descent method to calculate the AGC control gain G for the (i+1)th iteration.​i+1 .

[0118] AGC control gain G i+1 The calculation expression is:

[0119] ;

[0120] In the formula, a i is a step size, in order to ensure the optimization speed and the optimization accuracy, the step size a i is inversely proportional to the detection number i, that is, a i = δ / i, δ is an initial step value, when i=1, P0=0, G0=0.

[0121] Step 2.8 is to judge whether G i+1 is in the adjustment range of the AGC gain, if it is in the range, G i+1 is not adjusted; if it is not in the range, G i+1 is truncated to the gain value closest to G i+1 in the AGC gain adjustment range.

[0122] Step 2.9 is to set the AM transmit power detection number to i=i+1, and repeat steps 2.2-2.5.

[0123] The carrier signal amplitude calibration is completed, and the carrier signal amplitude works in the calibrated amplitude state, and then the modulation signal amplitude calibration is started. The gain of the control AGC is the calibrated gain, so as to ensure that the carrier signal amplitude calibration is completed before the modulation signal amplitude calibration, and the carrier signal amplitude works in the calibrated amplitude state, and then the modulation signal amplitude calibration is started.

[0124] S23, AM modulation depth detection is performed on the AM envelope digital signal based on the interaction signal to obtain the AM modulation depth, and preliminary AM modulation signal amplitude calibration is performed according to the AM modulation depth to obtain a preliminary AM modulation signal amplitude calibration result.

[0125] Specifically, the AM modulation depth detection is performed on the AM envelope digital signal based on the interaction signal to obtain the AM modulation depth, and the preliminary AM modulation signal amplitude calibration is performed according to the AM modulation depth to obtain a preliminary AM modulation signal amplitude calibration result, which includes:

[0126] S231, based on the interaction signal, setting the AM modulation depth detection number and the DAC output gain adjustment number;

[0127] S232, setting the adjusted DAC output gain according to the DAC output gain adjustment number; and setting the digital potentiometer gear position during the AM modulation depth detection according to the AM modulation depth detection number;

[0128] S233, AM envelope digital signal is modulated to obtain the AM modulation depth, and the modulation depth difference is calculated according to the AM modulation depth, and the modulation depth difference is modulated to judge the modulation depth fluctuation;

[0129] S234, based on the modulation depth fluctuation judgment result, the preliminary AM modulation signal amplitude calibration is carried out, and the preliminary AM modulation signal amplitude calibration result is obtained.

[0130] Specifically, based on the modulation depth fluctuation judgment result, the preliminary AM modulation signal amplitude calibration is carried out, and the preliminary AM modulation signal amplitude calibration result is obtained, including:

[0131] If the modulation depth fluctuation judgment result is that the modulation depth meets the modulation depth fluctuation requirement, the adjusted DAC output gain and the setting parameter of the digital potentiometer gear are stored in the storage medium, the preliminary modulation signal amplitude calibration is completed, and the preliminary AM modulation signal amplitude calibration result is obtained;

[0132] If the modulation depth fluctuation judgment result is that the modulation depth does not meet the modulation depth fluctuation requirement, it is judged whether the AM modulation depth detection times is greater than or equal to the maximum value of the AM modulation depth detection times;

[0133] If the AM modulation depth detection times is less than the maximum value of the AM modulation depth detection times, the gradient descent method is used to update the digital potentiometer gear, and the range judgment and adjustment of the updated digital potentiometer gear are carried out, and the adjusted digital potentiometer gear is obtained;

[0134] If the AM modulation depth detection times is greater than or equal to the maximum value of the AM modulation depth detection times, it is judged whether the adjusted DAC output gain is less than or equal to the minimum value of the DAC output gain;

[0135] If the adjusted DAC output gain is less than or equal to the minimum value of the DAC output gain, the adjusted DAC output gain and the setting parameter of the digital potentiometer gear are stored in the storage medium, the preliminary modulation signal amplitude calibration is completed, and the preliminary AM modulation signal amplitude calibration result is obtained;

[0136] If the adjusted DAC output gain is greater than the minimum value of the DAC output gain, the adjusted DAC output gain is subtracted by the DAC gain adjustment step, and the range judgment and adjustment of the updated DAC output gain are carried out, and the adjusted DAC output gain is obtained;

[0137] According to the adjusted digital potentiometer gear and the adjusted DAC output gain, the modulation depth fluctuation judgment and the digital potentiometer gear and DAC output gain updating process are repeated, the preliminary modulation signal amplitude calibration is completed, and the preliminary AM modulation signal amplitude calibration result is obtained.

[0138] Specifically, after receiving the interaction signal sent by the carrier signal amplitude calibration module, the modulation signal amplitude calibration module starts the modulation signal amplitude calibration. The modulation signal amplitude calibration processing diagram in the AM modulation depth calibration processing module is shown in Figure 6 . Figure 6 The modulation signal amplitude calibration processing module is used to process the AM envelope digital signal, the storage medium control signal and the interaction signal, and output the DAC gain control signal, the digital potentiometer control signal and the interaction signal.

[0139] The modulation signal amplitude calibration module uses the AM envelope digital signal to detect the AM modulation depth. According to the detected AM modulation depth, the DAC gain control signal is sent to control the output gain of the DAC, and the digital potentiometer control signal is sent to control the gear of the digital potentiometer, until the AM modulation depth meets the target depth requirement. The modulation signal amplitude calibration module sends the storage medium control signal to store the DAC gain control parameter and the digital potentiometer gear control parameter into the storage medium, and completes the modulation signal amplitude calibration. The modulation signal amplitude calibration flow chart is shown in Figure 7 , and the detailed steps are as follows:

[0140] Step 3.1 sets the AM modulation depth detection times k as the initial value k=1, and the DAC output gain adjustment times q as the initial value q=1.

[0141] Step 3.2 sends the DAC gain control signal, and sets the DAC output gain G q of the qth adjustment q=1, G q is set as the maximum value of the DAC output gain G max .

[0142] Step 3.3 sends the digital potentiometer control signal, and sets the gear S k of the digital potentiometer in the kth AM modulation depth detection.

[0143] Step 3.4, after the modulation signal amplitude calibration module obtains the AM envelope digital signal of two periods, finds the maximum value EMAX k and the minimum value EMIN k of the AM envelope digital signal of two periods, and calculates the AM modulation depth MD k of the kth AM modulation depth detection. The calculation expression of the AM modulation depth is:

[0144] .

[0145] Step 3.5 calculates the difference AM between the kth detected AM modulation depth MD k and the target modulation depth MD opt . k =MDk -MD opt .

[0146] Step 3.6 is to judge the kth detection, calculate the modulation depth difference value AMD k whether to meet the modulation depth fluctuation requirements, if it meets the modulation depth fluctuation requirements, send the storage medium control signal to store the qth DAC gain G q Setting parameters and the kth digital potentiometer gear S k Setting parameters into the storage medium, completing the modulation signal amplitude calibration; if it does not meet the modulation depth fluctuation requirements, proceed to step 3.7.

[0147] Step 3.7 is to judge whether the AM modulation depth detection times k is less than the maximum value of AM modulation depth detection times k max , if k < k max , then buffer the kth AM modulation depth detection value MD k and the digital potentiometer gear value S k , then proceed to steps 3.11~3.13; if k ≥ k max , proceed to step 3.8.

[0148] Step 3.8 is to judge whether the output gain G q of the DAC is less than or equal to the minimum value G min of the DAC output gain, if G q ≤ G min , store the qth DAC gain G q Setting parameters and the kth digital potentiometer gear S k Setting parameters into the storage medium, completing the modulation signal amplitude calibration; if G q > G min , reduce the output gain of the DAC by the DAC gain adjustment step AG, that is, G q+1 =G q -AG.

[0149] Step 3.9 is to judge whether G q+1 is within the adjustment range of the DAC gain, if it is within the range, G q+1 does not adjust; if it is not within the range, truncate G q+1 to the gain value closest to G q+1 within the AGC gain adjustment range.

[0150] Step 3.10 is to adjust the AM modulation depth detection times k = 1, the DAC output gain setting times q = q + 1, and then repeat steps 3.2~3.6.

[0151] Step 3.11 is to use the gradient descent method to calculate the k+1th digital potentiometer control gear Sk+1 .

[0152] ;

[0153] In the formula, β k Let β be the step size. To ensure both optimization speed and accuracy, the step size is β. k The relationship between β and the number of tests k is an inverse proportional function, i.e., β k =γ / k, where γ is the initial step value. When k=1, MD0=0 and S0=0.

[0154] Step 3.12 is to determine S k+1 Is it within the adjustment range of the digital potentiometer? If it is, S k+1 No adjustment is made; if it is outside the range, then S... k+1 Cut off within the range of digital potentiometer adjustment and S k+1 The closest gear value;

[0155] Step 3.13 sets the number of AM modulation depth detections to k=k+1, and repeats steps 3.3 to 3.6.

[0156] S3. Based on the preliminary amplitude calibration results, generate the control signal for the AM transmission link. According to the control signal of the AM transmission link, traverse the working frequency range of the AM transmission link and execute S2 point by point to complete the AM modulation depth calibration.

[0157] Specifically, after completing the carrier signal amplitude calibration and modulation signal amplitude calibration of the initial carrier operating frequency of the AM transmit link, the control module sends the carrier frequency control signal and the frequency hopping filter segment code control signal (i.e., the control signal of the AM transmit link) to control the frequency of the carrier signal output by the radio frequency signal source and the passband range of the frequency hopping filter. It traverses the operating frequency band range of the AM transmit link and performs S2 calibration on a frequency-by-frequency basis to complete the carrier signal amplitude calibration and modulation signal amplitude calibration, thus completing the AM modulation depth calibration.

[0158] like Figure 2 As shown, according to another embodiment of the present invention, an AM transmission signal modulation depth calibration device is provided, the AM transmission signal modulation depth calibration device comprising: an AM transmission link and an AM detection and control link;

[0159] The AM transmit link is used to receive the control signal output from the AM detection and control link and output the AM amplitude modulation signal.

[0160] Specifically, the AM transmit link includes: frequency hopping filter, power amplifier, automatic gain control circuit, automatic level control circuit, digital potentiometer, digital-to-analog converter, and radio frequency signal source;

[0161] a digital-to-analog converter configured to receive a digital-to-analog converter gain control signal and a calibration sequence signal and output a first modulating signal;

[0162] a digital potentiometer configured to receive a digital potentiometer notch control signal and the first modulating signal and output a second modulating signal;

[0163] a radio frequency signal source configured to receive a carrier frequency control signal and output a carrier signal;

[0164] an automatic level control circuit configured to receive the carrier signal and a filtered AM envelope signal and complete AM modulation;

[0165] an automatic gain control circuit configured to receive an automatic gain control circuit gain control signal and amplify an AM modulated signal output by the automatic level control circuit;

[0166] a power amplifier configured to amplify the AM modulated signal output by the automatic gain control circuit;

[0167] a frequency hopping filter configured to receive a frequency hopping filter segment code control signal and filter out external interference signals from the AM modulated signal output by the power amplifier;

[0168] a first pin of the frequency hopping filter is connected to one end of the power amplifier, another end of the power amplifier is connected to a first pin of the automatic gain control circuit, a second pin of the automatic gain control circuit is connected to a first pin of the automatic level control circuit, a second pin of the automatic level control circuit is connected to one end of the radio frequency signal source, a third pin of the automatic level control circuit is connected to a first pin of the digital potentiometer, and a second pin of the digital potentiometer is connected to a first pin of the digital-to-analog converter.

[0169] an AM detection control link configured to generate a control signal for controlling the AM transmission link and complete modulation depth calibration.

[0170] Specifically, the AM detection control link includes a directional coupler, a detector, a low-pass filter, an analog-to-digital converter, a control processor, and a storage medium.

[0171] the directional coupler is configured to couple the AM modulated signal and output a coupled AM modulated signal;

[0172] the detector is configured to receive the coupled AM modulated signal and output two-way AM envelope signals;

[0173] the low-pass filter is configured to filter the AM envelope signals and input the filtered AM envelope signals to the automatic level control circuit;

[0174] the analog-to-digital converter is configured to convert the AM envelope signals into AM envelope digital signals;

[0175] The control processor is used for AM modulation depth calibration of the received AM envelope digital signal, and outputs a carrier frequency control signal, a frequency hopping filter section 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.

[0176] The storage medium is used for receiving the storage medium control signal and storing the control parameters of the AM modulation depth calibration.

[0177] One end of the directional coupler is connected with the 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 the fourth pin of the automatic level control circuit, the other end of the analog-to-digital converter is connected with the first pin of the control processor, the second pin, the third pin and the fourth pin of the control processor are connected with one end of the storage medium respectively, the fifth pin of the control processor is connected with the third pin of the digital potentiometer, the sixth pin of the control processor is connected with the second pin of the digital-to-analog converter, the seventh pin of the control processor is connected with the third pin of the digital-to-analog converter, the eighth pin of the control processor is connected with the other end of the radio frequency signal source, the ninth pin of the control processor is connected with the third pin of the frequency hopping filter, and the tenth pin of the control processor is connected with the third pin of the automatic gain control circuit.

[0178] In summary, the AM transmitting signal modulation depth calibration method and device provided by the application have high efficiency, high precision and low cost, can be applied to AM transmitter transmitting power and modulation depth calibration, and are suitable for large-scale deployment on production lines. The key points are the carrier signal amplitude calibration method and the modulation signal amplitude calibration, and the larger the AGC dynamic range in the device is, the higher the AM transmitting power calibration precision is; the larger the DAC output gain dynamic range is, the smaller the gain adjustment step is, the more the digital potentiometer adjustable gears are, and the higher the AM modulation depth calibration precision is.

[0179] In the application, the AM transmitting power is detected by reducing the redundancy of the AM envelope digital signal data through digital downsampling, saving the hardware resources of the control processor, then inputting the AM envelope digital signal after digital downsampling into a digital low-pass filter, outputting the amplitude voltage U of the AM carrier signal by the digital low-pass filter, and calculating the AM transmitting power through the mean square value of the amplitude voltage U of the carrier signal, wherein the digital low-pass filter includes but is not limited to an IIR filter and an FIR filter, and the sampling frequency of the AM envelope digital signal after digital downsampling meets the low-pass sampling theorem.

[0180] In the application, the gradient descent method is used for carrier signal amplitude calibration, and the AM transmitting powers P i , Pi-1 The AGC gain G set before and after. i G i-1 Perform gradient calculation and detect power P i With target power P opt The difference ∆P i The sign of the gradient descent method determines the iterative optimization direction, and the step size α is... i The step size α is inversely proportional to the number of AM transmit power detections (i), ensuring both optimization speed and accuracy. i The relationship between the number of AM transmit power detections (i) and other functions includes, but is not limited to, an inverse proportional function relationship, requiring only a step α. i The value can be decreased as the number of AM transmit power detections (i) increases.

[0181] This invention calibrates the amplitude of the modulated signal through two-stage adjustment of the DAC output gain and the digital potentiometer range. The DAC output gain G... q Adjust the gain step ∆G with a negative slope to maintain the DAC output gain G. q With the setting unchanged, the gradient descent method is used to optimize the digital potentiometer setting S. k Using the AM modulation depth MD detected in the two tests before and after k MD k-1 and the digital potentiometer setting S before and after. k S k-1 Gradient calculation is performed to detect the modulation depth MD. k With target modulation depth MD opt The difference ∆MD k The sign of the gradient descent method determines the iterative optimization direction, and the step size β is... k The number of AM modulation depth detections, k, is also inversely proportional to the given number of detections, ensuring both optimization speed and accuracy. The step β... k The relationship between the number of AM modulation depth detections k and other functions includes, but is not limited to, an inverse proportional function relationship, requiring only a step β. k The value can be decreased as the number of AM modulation depth detections k increases.

[0182] To sum up, by means of the above technical solutions of the present application, the modulation depth of the AM transmitting signal meets the corresponding standard requirements through carrier signal amplitude calibration and modulation signal amplitude calibration, so as to improve the precision of the AM transmitter transmitting power and modulation depth, and further improve the transmission quality and power utilization rate of the AM transmitting signal, and ensure the signal transmission efficiency; the present application uses a low-cost carrier signal amplitude and modulation signal amplitude internal calibration method, without expensive instruments such as spectrum analyzers and power meters, which is suitable for large-scale deployment in production lines; and by performing carrier signal amplitude calibration before modulation signal amplitude calibration, the automatic level control circuit is calibrated under the premise of an accurate power reference signal, which greatly reduces the influence of AM transmitting power fluctuation on AM modulation depth, and improves the precision of AM modulation depth calibration; by using digital downsampling and digital low-pass filters in the carrier signal amplitude calibration method, the out-of-band noise is filtered out, the noise power is greatly reduced, and the AM transmitting power detection precision is improved; and the gradient descent method is used to optimize the AGC control gain, which ensures the optimization speed and improves the calibration precision of the carrier signal amplitude; and by using two-stage control of DAC output gain and digital potentiometer gear in the modulation signal amplitude calibration method, the total adjustment range of variables in the modulation signal amplitude calibration process is increased, so that the modulation signal amplitude calibration precision is higher, and the adjustment of the digital potentiometer gear uses the gradient descent method, which ensures the optimization speed and improves the calibration precision of the modulation signal amplitude.

[0183] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calibrating the modulation depth of an AM transmitted signal, characterized in that, The method includes: S1. Initialize the AM transmission link according to the control signal sent by the AM detection and control link to obtain the initial AM amplitude modulation signal; S2. Perform signal conversion on the initial AM amplitude modulation signal to obtain the AM envelope digital signal, and perform preliminary AM carrier signal and modulation signal amplitude calibration based on the AM envelope digital signal to obtain preliminary amplitude calibration results. S3. Based on the preliminary amplitude calibration results, generate the control signal for the AM transmission link. According to the control signal of the AM transmission link, traverse the working frequency range of the AM transmission link and execute S2 point by point to complete the AM modulation depth calibration.

2. The AM transmission signal modulation depth calibration method according to claim 1, characterized in that, The control signals sent by the AM detection and control link include carrier frequency control signals, frequency hopping filter segment code control signals, digital potentiometer range control signals, digital-to-analog converter gain control signals, and automatic gain control circuit gain control signals.

3. The AM transmission signal modulation depth calibration method according to claim 1, characterized in that, The initial AM amplitude modulated signal is converted to obtain an AM envelope digital signal, and preliminary amplitude calibration of the AM carrier signal and modulation signal is performed based on the AM envelope digital signal to obtain preliminary amplitude calibration results, including: S21. Perform a coupling operation on the initial AM amplitude modulation signal, obtain the AM envelope signal using a detector based on the coupling operation result, and perform signal conversion on the AM envelope signal to obtain the AM envelope digital signal. S22. Perform digital downsampling and filtering on the AM envelope digital signal to obtain the carrier signal amplitude voltage, and perform AM transmit power detection on the carrier signal amplitude voltage. Based on the detection results, perform preliminary AM carrier signal amplitude calibration to obtain the interactive signal. S23. Based on the interactive signal, the AM modulation depth of the AM envelope digital signal is detected to obtain the AM modulation depth. Based on the AM modulation depth, the amplitude of the AM modulation signal is preliminarily calibrated to obtain the preliminary AM modulation signal amplitude calibration result.

4. The AM transmission signal modulation depth calibration method according to claim 3, characterized in that, The process involves digital downsampling and filtering of the AM envelope digital signal to obtain the carrier signal amplitude voltage. AM transmit power is then detected on the carrier signal amplitude voltage. Based on the detection results, preliminary AM carrier signal amplitude calibration is performed to obtain the interactive signal, which includes: S221. Digitally downsample the AM envelope digital signal to obtain the downsampled AM envelope digital signal, and use a digital low-pass filter to filter the downsampled AM envelope digital signal to obtain the carrier signal amplitude voltage. S222. Initialize the number of AM transmit power detections, and set the AGC control gain for AM transmit power detection based on the number of detections. Perform AM transmit power detection on the carrier signal amplitude voltage to obtain the detection result. S223. Calculate the power difference based on the detection results, and make a power fluctuation judgment on the power difference. Based on the power fluctuation judgment result, perform preliminary AM carrier signal amplitude calibration to obtain the interactive signal.

5. The AM transmission signal modulation depth calibration method according to claim 4, characterized in that, The preliminary AM carrier signal amplitude calibration based on the power fluctuation judgment result yields the following interactive signals: If the power fluctuation judgment result is that the power difference meets the power fluctuation requirements, then the setting parameters of the AGC control gain are stored in the storage medium to complete the preliminary carrier signal amplitude calibration and obtain the interactive signal. If the power fluctuation judgment result is that the power difference does not meet the power fluctuation requirements, then it is determined whether the number of AM transmit power detections is greater than or equal to the maximum value of the number of AM transmit power detections. If the number of AM transmit power detections is greater than or equal to the maximum number of AM transmit power detections, the setting parameters of the AGC control gain are stored in the storage medium to complete the initial carrier signal amplitude calibration and obtain the interactive signal. If the number of AM transmit power detections is less than the maximum number of AM transmit power detections, then the gradient descent method is used to update the AGC control gain to obtain the updated AGC control gain. The updated AGC control gain is dynamically ranged, and the updated AGC control gain is adjusted based on the dynamic range judgment result to obtain the adjusted AGC control gain. After the AGC control gain is updated and adjusted, the number of AM transmit power detections is updated, and the power fluctuation judgment and AGC control gain update process are repeated to obtain the final AGC control gain. The final AGC control gain settings are stored in the storage medium to complete the initial carrier signal amplitude calibration and obtain the interactive signal.

6. The AM transmission signal modulation depth calibration method according to claim 3, characterized in that, The method involves performing AM modulation depth detection on the AM envelope digital signal based on the interactive signal to obtain the AM modulation depth, and then performing preliminary AM modulation signal amplitude calibration based on the AM modulation depth. The preliminary AM modulation signal amplitude calibration results include: S231. Based on the interactive signal, set the number of AM modulation depth detections and the number of DAC output gain adjustments; S232. Set the adjusted DAC output gain according to the number of DAC output gain adjustments, and set the digital potentiometer setting for AM modulation depth detection according to the number of AM modulation depth detections. S233. Perform AM modulation depth detection on the AM envelope digital signal to obtain the AM modulation depth, calculate the modulation depth difference based on the AM modulation depth, and judge the modulation depth fluctuation of the modulation depth difference. S234. Based on the modulation depth fluctuation judgment result, perform preliminary AM modulation signal amplitude calibration to obtain preliminary AM modulation signal amplitude calibration result.

7. The AM transmission signal modulation depth calibration method according to claim 6, characterized in that, The preliminary AM modulation signal amplitude calibration based on the modulation depth fluctuation judgment result yields the following preliminary AM modulation signal amplitude calibration results: If the modulation depth fluctuation judgment result is that the modulation depth meets the modulation depth fluctuation requirement, the adjusted DAC output gain and the setting parameters of the digital potentiometer range are stored in the storage medium to complete the preliminary modulation signal amplitude calibration and obtain the preliminary AM modulation signal amplitude calibration result. If the modulation depth fluctuation judgment result is that the modulation depth does not meet the modulation depth fluctuation requirement, then it is determined whether the number of AM modulation depth detections is greater than or equal to the maximum value of the number of AM modulation depth detections. If the number of AM modulation depth detections is less than the maximum number of AM modulation depth detections, the gradient descent method is used to update the digital potentiometer range, and the updated digital potentiometer range is judged and adjusted to obtain the adjusted digital potentiometer range. If the number of AM modulation depth detections is greater than or equal to the maximum number of AM modulation depth detections, then determine whether the adjusted DAC output gain is less than or equal to the minimum DAC output gain; if the adjusted DAC output gain is less than or equal to the minimum DAC output gain, then store the adjusted DAC output gain and the setting parameters of the digital potentiometer range in the storage medium to complete the preliminary modulation signal amplitude calibration and obtain the preliminary AM modulation signal amplitude calibration result. If the adjusted DAC output gain is greater than the minimum DAC output gain, then the adjusted DAC output gain is subtracted from the DAC gain adjustment step, and the updated DAC output gain is range-determined and adjusted to obtain the adjusted DAC output gain. Based on the adjusted digital potentiometer setting and the adjusted DAC output gain, the modulation depth fluctuation judgment and digital potentiometer setting and DAC output gain update processing are repeatedly performed to complete the preliminary modulation signal amplitude calibration and obtain the preliminary AM modulation signal amplitude calibration result.

8. An AM transmission signal modulation depth calibration apparatus, used to implement the AM transmission signal modulation depth calibration method according to any one of claims 1-7, characterized in that, The AM transmission signal modulation depth calibration device includes: an AM transmission link and an AM detection and control link; The AM transmission link is used to receive the control signal output by the AM detection and control link and output the AM amplitude modulation signal. The AM detection and control link is used to generate control signals to control the AM transmission link and complete modulation depth calibration; One end of the AM transmission link is connected to one end of the AM detection and control link.

9. The AM transmission signal modulation depth calibration device according to claim 8, characterized in that, The AM transmission link includes: 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 an RF signal source; The digital-to-analog converter is used to receive a digital-to-analog converter gain control signal and a calibration sequence signal, and to output a first modulation signal; The digital potentiometer is used to receive a digital potentiometer range control signal and a first modulation signal, and to output a second modulation signal; The radio frequency signal source is used to receive carrier frequency control signals and output carrier signals; The automatic level control circuit is used to receive the carrier signal and the filtered AM envelope signal to complete AM modulation; The automatic gain control circuit is used to receive the gain control signal from the automatic gain control circuit and amplify the AM amplitude modulation signal output by the automatic level control circuit. The power amplifier is used to amplify the AM modulation signal output by the automatic gain control circuit; The frequency hopping filter is used to receive the frequency hopping filter segment code control signal and to filter out external interference signals from the AM amplitude modulation signal output by the power amplifier. The first pin of the frequency hopping filter is connected to one end of the power amplifier, the other end of the power amplifier is connected to the first pin of the automatic gain control circuit, the second pin of the automatic gain control circuit is connected to the first pin of the automatic level control circuit, the second pin of the automatic level control circuit is connected to one end of the radio frequency signal source, the third pin of the automatic level control circuit is connected to the first pin of the digital potentiometer, and the second pin of the digital potentiometer is connected to the first pin of the digital-to-analog converter.

10. An AM transmission signal modulation depth calibration device according to claim 9, characterized in that, The AM detection and control link includes: 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 to couple AM ​​amplitude-modulated signals and output the coupled amplitude-modulated signals. The detector is used to receive the coupled amplitude-modulated signal and output two AM envelope signals; The low-pass filter is used to filter the AM envelope signal and input it to the automatic level control circuit. The analog-to-digital converter is used to convert the AM envelope signal into an AM envelope digital signal; The control processor is used to perform AM modulation depth calibration on the received AM envelope digital signal and output carrier frequency control signal, frequency hopping filter segment code control signal, digital potentiometer range control signal, digital-to-analog converter gain control signal, calibration sequence signal, storage medium control signal and automatic gain control circuit gain control signal. The storage medium is used to receive storage medium control signals and store control parameters for AM modulation depth calibration. One end of the directional coupler is connected to the second pin of the frequency hopping filter, and the other end of the directional coupler is connected to one end of the detector. The other end of the detector is connected to one end of the low-pass filter and one end of the analog-to-digital converter. The other end of the low-pass filter is connected to the fourth pin of the automatic level control circuit. The other end of the analog-to-digital converter is connected to the first pin of the control processor. The second, third, and fourth pins of the control processor are connected to one end of the storage medium. The fifth pin of the control processor is connected to the third pin of the digital potentiometer. The sixth pin of the control processor is connected to the second pin of the digital-to-analog converter. The seventh pin of the control processor is connected to the third pin of the digital-to-analog converter. The eighth pin of the control processor is connected to the other end of the radio frequency signal source. The ninth pin of the control processor is connected to the third pin of the frequency hopping filter. The tenth pin of the control processor is connected to the third pin of the automatic gain control circuit.

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