A method and device for detecting power of a multi-mode shortwave transmitter

Abstract

The present invention provides a multi-mode shortwave transmitter power detection method and device, which relates to the technical field of transmitter power detection, and realizes accurate power detection of transmission signals of different frequencies and different powers under various working modes of the transmitter, including pre-processing the output signal and reflected signal of the transmitter and converting them into digital signals; performing digital down-conversion processing on the digital signal to form a baseband signal, obtaining an I-channel signal and a Q-channel signal; squaring the I-channel signal and the Q-channel signal of the baseband signal respectively and then summing them, and accumulating the power through an accumulator; and calculating the power according to the power accumulation result. The present invention has the advantages of being adaptable to various working modes, simple calculation and accurate detection.

Description

Technical Field

[0001] The present invention relates to the technical field of transmitter power detection, and in particular to a multi-mode shortwave transmitter power detection method and device. Background Art

[0002] A shortwave AM transmitter is a device used for broadcasting and communications that is capable of transmitting AM signals within the shortwave frequency band (usually 2.3MHz to 26.1MHz).

[0003] The traditional power detection module used in the transmitter is usually composed of a directional coupler, a detector and a voltage sampling circuit. The directional coupler couples the output signal and the reflected signal and sends them to the detector for detection. After the voltage signal is formed, it is sent to the subsequent voltage sampling circuit for sampling. According to the voltage value obtained, the transmitter output power and the reflected power value can be calculated according to the pre-stored voltage-frequency-power calibration data. When the traditional power detection module works in single-frequency mode, it can measure the transmitter power more accurately. However, in the frequency hopping mode, since the detector output voltage cannot correspond to the current instantaneous working frequency, the frequency-power calibration data cannot correspond to the detection voltage, resulting in inaccurate power measurement. In the multi-frequency working mode, since the signals of each frequency point are transmitted at the same time, the detector can only output the total value of the power values ​​of all transmission frequency points, and cannot distinguish the transmission power of each frequency point. At the same time, due to the nonlinear characteristics of the power-voltage response of the detector, during power calibration, it is necessary to perform multi-point power value calibration at different power levels to fit the power-voltage response curve, which greatly increases the workload of power display calibration.

[0004] Based on the shortcomings of traditional power detection, it is necessary to improve the power detection method of the transmitter to achieve accurate power detection of transmission signals of different frequencies and different powers under various working modes of the transmitter. Summary of the invention

[0005] The object of the present invention is to provide a multi-mode shortwave transmitter power detection method and device, which can realize accurate power detection of transmission signals of different frequencies and different powers under multiple working modes of the transmitter.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention first provides a multi-mode shortwave transmitter power detection method, comprising the following steps:

[0008] Pre-process the transmitter's output signal and reflected signal and convert them into digital signals;

[0009] Performing digital down-conversion processing on the digital signal to form a baseband signal, and obtaining an I-channel signal and a Q-channel signal;

[0010] The I-path signal and the Q-path signal of the baseband signal are squared and then summed to obtain , and accumulate the power through the accumulator;

[0011] The power is calculated based on the power accumulation result.

[0012] Preferably, the method of preprocessing the output signal and the reflected signal of the transmitter and converting them into digital signals is:

[0013] The output signal and the reflected signal of the transmitter are coupled and outputted respectively through a directional coupler and sent to a radio frequency switch for selected output. The output signal of the radio frequency switch is amplified by a variable gain amplifier and then sent to an analog-to-digital converter for sampling to form a digital signal.

[0014] Preferably, in the single-frequency and multi-frequency modes, when calculating the power according to the power accumulation result, the power accumulation times L and the operating frequencies of the K frequency points are set to , measure the The power of each frequency point is:

[0015] Set the NCO frequency to , For the first The working frequency of each frequency point;

[0016] The RF switch selects the output coupling signal or the reflected coupling signal, and sets the variable gain amplifier to be connected to the first The gain corresponding to the frequency point, the accumulator is reset to zero;

[0017] Perform the power accumulation until the number of accumulations reaches L times;

[0018] Calculate the corresponding output power or reflected power based on the calibration parameters and the output value of the accumulator

[0019] Preferably, in the frequency hopping mode, when calculating the power according to the power accumulation result, the power accumulation times L is set, and the frequency hopping working frequency is , the method to measure the power of all frequencies is:

[0020] Step S401: selecting an output coupling signal or a reflected coupling signal through the RF switch, and clearing the accumulator;

[0021] Step S402: Setting the frequency of the NCO to the current frequency hopping operating frequency, and setting the gain corresponding to the frequency point for the variable gain amplifier;

[0022] Step S403: performing a power accumulation operation on the accumulator during the current frequency hopping working time, and stopping the accumulation if the accumulated count reaches L before the frequency hopping working time ends; otherwise, suspending the accumulation operation at the end of the frequency hopping working time;

[0023] Step S404: after the current frequency hopping working time ends, if the accumulated count reaches L, the output value of the accumulator at the current frequency hopping working frequency is output, and the corresponding output power or reflected power is calculated according to the calibration parameter and the output value of the accumulator;

[0024] Step S405: updating the current frequency-hopping operating frequency, and repeating steps S402 to S404 until the output values ​​of the accumulators at all the frequency-hopping operating frequencies are obtained.

[0025] Preferably, the method for calculating the corresponding output power or reflected power according to the calibration parameter and the output value of the accumulator is:

[0026] Establishing and fitting the linear relationship between the output value of the accumulator and the corresponding output power and reflected power respectively, wherein the calibration parameter is the coefficient of the linear relationship;

[0027] Based on the linear relationship, the corresponding output power or the reflected power is calculated according to the calibration parameter and the output value of the accumulator.

[0028] Preferably, the method for obtaining the calibration parameters is:

[0029] Select within the transmit frequency band Frequency points ,in , ;

[0030] Set the transmitter to single frequency transmission mode, so that the transmitter works at the selected frequency. superior, , measure the power at this frequency using a power meter , obtain the output value through the accumulator , get the frequency Calibration parameters :

[0031] .

[0032] Preferably, when the transmitter is operating except Other frequencies Time, frequency The calibration parameters The method to obtain is:

[0033] Said Frequency points Divide the entire frequency band into N frequency bands and obtain The two endpoint values ​​of the frequency band and , , ;

[0034] Get frequency Calibration parameters :

[0035] ;

[0036] in, and The frequency points and The corresponding calibration parameters.

[0037] The present invention also provides a multi-mode shortwave transmitter power detection device, which is applied to the above-mentioned multi-mode shortwave transmitter power detection method, and comprises a directional coupler, a radio frequency switch, a variable gain amplifier, an analog-to-digital converter and a digital signal processing module connected in sequence;

[0038] The directional coupler, the RF switch, the variable gain amplifier and the analog-to-digital converter are used to pre-process the output signal and the reflected signal of the transmitter and convert them into digital signals;

[0039] The digital signal processing module is used to perform digital down-conversion processing on the digital signal to form a baseband signal, and square the I-channel signal and the Q-channel signal of the baseband signal respectively and then sum them to obtain The power is accumulated through the accumulator, and finally the power is calculated according to the power accumulation result.

[0040] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0041] The present invention pre-processes the output signal and the reflected signal of the transmitter and converts them into digital signals, so that the processing target can be flexibly switched to be the output signal or the reflected signal, and the accuracy and stability of signal processing can be effectively improved;

[0042] The present invention realizes accurate power detection of transmission signals of different frequencies and different powers under various working modes of the transmitter, and has stronger adaptability;

[0043] The processing of the I-path signal and the Q-path signal by the present invention can fully capture the amplitude information of the signal, avoid the power error caused by the phase change, and also help to reduce the influence of random interference in a short time on the calculation result, thereby improving the accuracy of the power calculation;

[0044] The present invention calculates power according to the power accumulation result, realizes real-time monitoring of signal power, and the accumulator result based on the method of the present invention and the power of the signal are in a linear relationship. Compared with the N-fold curve fitting relationship for calculating power in other conventional solutions, the fitting parameters are easier to determine, the power calculation is also simpler, and has a higher computing power cost performance;

[0045] The invention has reasonable design and simple calculation, and improves the signal processing efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of a process for processing a digital signal provided by an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a measurement output signal for power detection of a multi-mode shortwave transmitter provided by an embodiment of the present invention;

[0048] Figure 3 A schematic diagram of measuring reflected signals for power detection of a multi-mode shortwave transmitter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0050] Example 1

[0051] This embodiment provides a multi-mode shortwave transmitter power detection method, comprising the following steps:

[0052] Pre-process the transmitter's output signal and reflected signal and convert them into digital signals;

[0053] Performing digital down-conversion processing on the digital signal to form a baseband signal, and obtaining an I-channel signal and a Q-channel signal;

[0054] The I-path signal and the Q-path signal of the baseband signal are squared and then summed to obtain , and accumulate the power through the accumulator;

[0055] The power is calculated based on the power accumulation result.

[0056] This embodiment can be adaptively applied to various modes such as frequency hopping, single frequency and multi-frequency modes, and has wider applicability and adaptability. At the same time, the simple processing helps to improve the efficiency of signal processing and has high measurement accuracy. The schematic diagram of the process of processing digital signals can be found in Figure 1 , the digital signal is low-pass filtered under the action of NCO and finally obtains I-channel signal and Q-channel signal. NCO is a digitally controlled oscillator that outputs a sinusoidal signal and cosine signal , where t is time, is the angular frequency.

[0057] In this embodiment, the method of preprocessing the output signal and the reflected signal of the transmitter and converting them into digital signals is:

[0058] The output signal and the reflected signal of the transmitter are coupled and outputted respectively through a directional coupler and sent to a radio frequency switch for selected output. The output signal of the radio frequency switch is amplified by a variable gain amplifier and then sent to an analog-to-digital converter for sampling to form a digital signal.

[0059] Normally, the coupling amount of the directional coupler at different frequencies will also vary greatly, and the reflected power is much smaller than the output power. Therefore, this embodiment introduces a variable gain amplifier to effectively compensate for the frequency response of the directional coupler. At frequencies with low coupling amounts, the gain of the variable gain amplifier can be increased, thereby reducing the power difference of the coupled signal between different frequencies. At the same time, when detecting the reflected power, increasing the gain of the variable gain amplifier can also reduce the difference between the output coupling and the reflected coupling power. Gain control can ensure that the input signal amplitude of the analog-to-digital converter is in a reasonable working range, thereby ensuring the dynamic range characteristics of the entire power sampling system.

[0060] When calculating the power specifically, in single-frequency and multi-frequency modes, when calculating the power according to the power accumulation result, the power accumulation times L and the working frequencies of the K frequency points are set to , measure the The power of each frequency point is:

[0061] Set the NCO frequency to , For the first The working frequency of each frequency point;

[0062] The RF switch selects the output coupling signal or the reflected coupling signal, and sets the variable gain amplifier to be connected to the first The gain corresponding to the frequency point, the accumulator is reset to zero;

[0063] Perform the power accumulation until the number of accumulations reaches L times;

[0064] Calculate the corresponding output power or reflected power based on the calibration parameters and the output value of the accumulator

[0065] On the other hand, in the frequency hopping mode, when the power is calculated according to the power accumulation result, the power accumulation times L are set, and the frequency hopping working frequency is , the method to measure the power of all frequencies is:

[0066] Step S401: selecting an output coupling signal or a reflected coupling signal through the RF switch, and clearing the accumulator;

[0067] Step S402: Setting the frequency of the NCO to the current frequency hopping operating frequency, and setting the gain corresponding to the frequency point for the variable gain amplifier;

[0068] Step S403: performing a power accumulation operation on the accumulator during the current frequency hopping working time, and stopping the accumulation if the accumulated count reaches L before the frequency hopping working time ends; otherwise, suspending the accumulation operation at the end of the frequency hopping working time;

[0069] Step S404: after the current frequency hopping working time ends, if the accumulated count reaches L, the output value of the accumulator at the current frequency hopping working frequency is output, and the corresponding output power or reflected power is calculated according to the calibration parameter and the output value of the accumulator;

[0070] Step S405: updating the current frequency-hopping operating frequency, and repeating steps S402 to S404 until the output values ​​of the accumulators at all the frequency-hopping operating frequencies are obtained.

[0071] It should be noted that when processing signals, the RF switch is used to select whether to process the output signal or the reflected signal. Therefore, the RF switch selects the signal, and the final output is the power of the corresponding signal.

[0072] Finally, the method for calculating the corresponding output power or reflected power according to the calibration parameter and the output value of the accumulator is:

[0073] Establishing and fitting the linear relationship between the output value of the accumulator and the corresponding output power and reflected power respectively, wherein the calibration parameter is the coefficient of the linear relationship;

[0074] Based on the linear relationship, the corresponding output power or the reflected power is calculated according to the calibration parameter and the output value of the accumulator.

[0075] Furthermore, the method for obtaining the calibration parameters is:

[0076] Select within the transmit frequency band Frequency points ,in , ;

[0077] Set the transmitter to single frequency transmission mode, so that the transmitter works at the selected frequency. superior, , measure the power at this frequency using a power meter , obtain the output value through the accumulator , get the frequency Calibration parameters :

[0078] .

[0079] As a preferred solution, when the transmitter is working except Other frequencies Time, frequency The calibration parameters The method to obtain is:

[0080] Said Frequency points Divide the entire frequency band into N frequency bands and obtain The two endpoint values ​​of the frequency band and , , ;

[0081] Get frequency Calibration parameters :

[0082] ;

[0083] in, and The frequency points and The corresponding calibration parameters.

[0084] In the above calculation, That is, the frequency The calibration parameters, Represents the frequency point, which can be , .

[0085] The hardware schematic diagram relied on by this embodiment can be found in Figure 2-Figure 3 ,in Figure 2 The power meter measures the output signal and is therefore suitable for obtaining a linear relationship between the power of the output signal and the output of the accumulator. On the contrary, Figure 3The power meter measures the reflected signal and is therefore suitable for obtaining a linear relationship between the power of the reflected signal and the output of the accumulator.

[0086] Since the digital signal processing method used in this embodiment has a linear characteristic for power detection, under the same frequency and different power conditions, the ratio of the output value of the digital signal processing module to the actual power is a fixed coefficient. The use of digital signal processing can effectively reduce the workload of the power calibration step. However, the output voltage and actual power of the traditional diode detection method are nonlinear. If a quadratic curve is used, To fit, it is necessary to collect at least three voltage data at different powers at the same frequency. The workload of power calibration is three times that of digital signal processing. To fit the signal, it is necessary to collect voltage data corresponding to at least four different powers at the same frequency. The workload of power calibration is four times that of the digital signal processing method.

[0087] It should be noted that in addition to calculating the linear relationship for different frequency points separately, the reflected signal and the output signal are also determined independently. When the power of the final output signal is detected, the corresponding predetermined linear relationship is selected according to the frequency point and the signal type selected by the RF switch to output the final result.

[0088] The following is a practical application case:

[0089] In the shortwave transmitter, the directional coupler adopts the RF coaxial coupler. The coupling amount of the coupler is -80dB at 2.3MHz and -57dB at 26.1MHz. When measuring the output power of the 2.3MHz signal, the gain of the variable gain amplifier is set to 30dB, and when measuring the output power of the 26.1MHz signal, the gain of the variable gain amplifier is set to 10dB. When measuring the reflected power of the 2.3MHz signal, the gain of the variable gain amplifier is set to 40dB, and when measuring the reflected power of the 26.1MHz signal, the gain of the variable gain amplifier is set to 20dB. This ensures that the power of the signal sent to the analog-to-digital converter is not much different, thereby ensuring the measurement accuracy and dynamic range of the analog-to-digital converter. The exciter part has an adaptive pre-distortion function, an output signal RF feedback path and an analog-to-digital converter. Add a reflected signal input RF interface in the exciter, add an RF switch, and use the amplifier circuit and analog-to-digital converter used in the adaptive pre-distortion function to sample the signal. The digital signal processing function of power detection and the digital signal processing function of signal modulation are implemented using the same field programmable array FPGA. In order to ensure that the 20Hz audio signal can be sampled into one cycle, the power accumulation time is selected as 60ms. The frequency step is 2.30MHz, 2.53MHz, 2.78MHz, ... 24.92MHz, 26.1MHz and 27 other frequency points are selected for power calibration.

[0090] Example 2

[0091] This embodiment provides a multi-mode shortwave transmitter power detection device, which is applied to a multi-mode shortwave transmitter power detection method in Embodiment 1, comprising a directional coupler, a radio frequency switch, a variable gain amplifier, an analog-to-digital converter, and a digital signal processing module connected in sequence;

[0092] The directional coupler, the RF switch, the variable gain amplifier and the analog-to-digital converter are used to pre-process the output signal and the reflected signal of the transmitter and convert them into digital signals;

[0093] The digital signal processing module is used to perform digital down-conversion processing on the digital signal to form a baseband signal, and square the I-channel signal and the Q-channel signal of the baseband signal respectively and then sum them to obtain The power is accumulated through the accumulator, and finally the power is calculated according to the power accumulation result.

[0094] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-mode shortwave transmitter power detection method, characterized in that: The following steps are involved: Pre-process the transmitter's output signal and reflected signal and convert them into digital signals; Performing digital down-conversion processing on the digital signal to form a baseband signal, and obtaining an I-channel signal and a Q-channel signal; The I-path signal and the Q-path signal of the baseband signal are squared and then summed to obtain , and accumulate the power through the accumulator; Calculate the power according to the power accumulation result; The method of preprocessing the output signal and the reflected signal of the transmitter and converting them into digital signals is: The output signal and the reflected signal of the transmitter are coupled and outputted respectively through a directional coupler, and sent to a radio frequency switch for selective output. The output signal of the radio frequency switch is amplified by a variable gain amplifier and then sent to an analog-to-digital converter for sampling to form a digital signal; In the single-frequency and multi-frequency modes, when calculating the power according to the power accumulation result, the power accumulation times L are set, and the operating frequencies of the K frequency points are , measure the The power of each frequency point is: Set the NCO frequency to , For the first The working frequency of each frequency point; The RF switch selects the output coupling signal or the reflected coupling signal, and sets the variable gain amplifier to be connected to the first The gain corresponding to the frequency point, the accumulator is reset to zero; Perform the power accumulation until the number of accumulations reaches L times; Calculate the corresponding output power or reflected power according to the calibration parameters and the output value of the accumulator; When calculating the power according to the power accumulation result, the power accumulation times L is set, and the frequency of the frequency hopping is , the method to measure the power of all frequencies is: Step S401: selecting an output coupling signal or a reflected coupling signal through the RF switch, and clearing the accumulator; Step S402: Setting the frequency of the NCO to the current frequency hopping operating frequency, and setting the gain corresponding to the frequency point for the variable gain amplifier; Step S403: performing a power accumulation operation on the accumulator during the current frequency hopping working time, and stopping the accumulation if the accumulated count reaches L before the frequency hopping working time ends; otherwise, suspending the accumulation operation at the end of the frequency hopping working time; Step S404: after the current frequency hopping working time ends, if the accumulated count reaches L, the output value of the accumulator at the current frequency hopping working frequency is output, and the corresponding output power or reflected power is calculated according to the calibration parameter and the output value of the accumulator; Step S405: updating the current frequency hopping operating frequency, and repeating steps S402 to S404 until the output values ​​of the accumulator at all the frequency hopping operating frequencies are obtained; The method for calculating the corresponding output power or reflected power according to the calibration parameter and the output value of the accumulator is: Establishing and fitting the linear relationship between the output value of the accumulator and the corresponding output power and reflected power respectively, wherein the calibration parameter is the coefficient of the linear relationship; Based on the linear relationship, the corresponding output power or the reflected power is calculated according to the calibration parameter and the output value of the accumulator. The method for obtaining the calibration parameters is: Select within the transmit frequency band Frequency points ,in , ; Set the transmitter to single frequency transmission mode, so that the transmitter works at the selected frequency. superior, , measure the power at this frequency using a power meter , obtain the output value through the accumulator , get the frequency Calibration parameters : ； When the transmitter is operating except Other frequencies Time, frequency The calibration parameters The method to obtain is: Said Frequency points Divide the entire frequency band into N frequency bands and obtain The two endpoint values ​​of the frequency band and , , ; Get frequency Calibration parameters : ； in, and The frequency points and The corresponding calibration parameters.

2. A multi-mode shortwave transmitter power detection device, applied to a multi-mode shortwave transmitter power detection method as claimed in claim 1, characterized in that: It includes a directional coupler, a radio frequency switch, a variable gain amplifier, an analog-to-digital converter and a digital signal processing module connected in sequence; The directional coupler, the RF switch, the variable gain amplifier and the analog-to-digital converter are used to pre-process the output signal and the reflected signal of the transmitter and convert them into digital signals; The digital signal processing module is used to perform digital down-conversion processing on the digital signal to form a baseband signal, and square the I-channel signal and the Q-channel signal of the baseband signal respectively and then sum them to obtain The power is accumulated through the accumulator, and finally the power is calculated according to the power accumulation result.

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