CN114204949B - Large dynamic quick digital AGC control method - Google Patents
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Abstract
The large dynamic rapid digital automatic gain control AGC method disclosed by the invention has the advantages of high convergence rate, large dynamic range and short response time. The invention is realized by the following technical scheme: the digital AGC control circuit divides a channel link of the receiver into a radio frequency part and an intermediate frequency part, in the radio frequency part channel link, a radio frequency signal passes through a front-end first frequency hopping filter amplifying circuit, and after attenuation first step or superposition attenuation is realized through a first numerical control attenuator, the digital AGC radio frequency detection module carries out frequency mixing twice, and according to ADC output, the digital AGC radio frequency detection module adjusts radio frequency attenuation and intermediate frequency attenuation in real time and roughly adjusts link gain; the second parallel AGC feedback loop controls the intermediate frequency AGC by using the intermediate frequency detection wave and the AD sampling result through the intermediate frequency gain control module, fine adjusts the link, adjusts the intensity of the intermediate frequency output signal, controls the output power of the digital automatic gain control loop and completes the whole digital automatic gain control.
Description
Technical Field
The invention belongs to the field of wireless communication, and relates to a large dynamic and rapid digital automatic gain control method in a measurement and control and wireless short wave communication system, which can carry out accurate gain control on a wide-range radio frequency input signal of a receiver and output a signal meeting the requirements.
Background
In wireless communication, a communication system is affected by factors such as transmitting power, receiving and transmitting distance, radio wave propagation fading, electromagnetic environment interference and the like, and the level of a signal received by a receiver is dynamic and large, and the range of the signal is more than one hundred dB. While the range of signal levels that can be handled by the receiver is limited, an excessively strong signal will cause saturation or blocking of the link; and when the signal is too weak, the carrier-to-noise ratio is too low to sample the useful signal. When the receiver receives the radio signal, the power of each transmitting station is small, the distance between the transmitting station and the receiver is different, and the strength of the useful signal induced on the receiving antenna is quite different due to multipath effect, fading and other reasons in the radio wave propagation process, and the useful signal often has quite different fluctuation, so that certain circuits (such as detectors) can not work normally when receiving weak signals, and the signals are lost, and the blocking (nonlinear distortion) of an amplifying circuit is caused when receiving strong signals. In order to ensure the amplitude and signal quality of the output intermediate frequency signal of the receiver and the normal operation of the subsequent modules of the system, an automatic gain control circuit is used for compressing the variation range of the useful signal strength in the receiving equipment almost without exception, and an Automatic Gain Control (AGC) circuit is added in a link to solve the large-range fluctuation of the received signal. An Automatic Gain Control (AGC) circuit is an important circuit for ensuring stability of a reception amplitude in a radio receiving apparatus. The automatic gain control circuit is widely used in the receiver, is one of key control circuits in the receiver module, and has the function of improving the dynamic range of the receiver. The AGC circuit mainly comprises a control circuit and a controlled circuit. The control circuit is the generation part of AGC DC voltage, and the function of the controlled circuit is to change the gain of the receiver according to the changed control voltage generated by the control circuit. The digital control attenuator is generally composed of a level detector (peak detection circuit), a low-pass filter, a direct current amplifier, a voltage comparator, a control voltage generator and a controllable gain amplifier, and under the condition that the amplitude of an input signal is greatly changed, the digital control attenuator is quickly controlled through a digital AGC circuit by arranging the detection circuits in a radio frequency loop and an intermediate frequency loop of a receiver, and the amplitude of the output signal is automatically kept to be changed within a small range. The function of the automatic gain control is to amplify/attenuate the signals of different gears and to "map" the range of the input signals of each gear to the optimal operating range of the ADC device. The Automatic Gain Control (AGC) circuit can automatically adjust the gain of the amplifier and the intensity of the intermediate frequency output signal according to the voltage of the input signal, so that the amplitude of the intermediate frequency output signal is controlled in an AD dynamic range, when the level of the input signal changes, the output voltage of the amplifier changes in a certain range, and the receiver outputs an intermediate frequency signal with almost constant amplitude. The gain of the receiver is adjusted along with the strength of the signal, and the performance of the receiver directly influences whether the receiver can stably receive with high quality. The traditional AGC circuit mostly adopts an analog circuit, but because the analog AGC lacks intelligence, a complex control algorithm is difficult to realize, the precision is not high, and the debugging is complex.
The distance of the receiver from the radiation source may vary considerably; the radio wave has obvious fading phenomenon in space propagation; as well as other interference factors, cause significant variations and fluctuations in the signal strength applied to the receiver input. However, the terminal device of the receiver generally can only process signals with small amplitude variation, and the terminal device is disabled due to too strong or too weak signals or negligence. Thus, automatic gain control is emphasized very well in the receiver to ensure the stationarity of the receiver output signal amplitude. In the field of wireless communication, conventional receivers commonly use analog and digital methods for controlling gain. The analog method controls the gain by changing the DC operating state of the transistor. When Ic is changed, the forward transmission admittance is also changed, and the gain is also changed. The forward AGC achieves gain control with an increase Ic and the reverse AGC achieves gain control with a decrease Ic, both of which decrease gain, but the dynamic range that is typically controllable is not large. And meanwhile, as the working temperature rises, the gain stabilizing range also changes. The analog AGC method adopts a relatively complex circuit, occupies a larger space of a channel circuit, has higher circuit cost, has slower AGC release time because the hardware is complex to realize, can not quickly return to a reference control quantity when the signal amplitude is quickly changed, can not flexibly adjust the AGC stabilization time, can not meet the different requirements of various waveforms on the AGC response time, can only compromise design, can not accurately realize the control quantity of a channel, and can not accurately estimate the signal intensity input by an antenna according to the state of the AGC, so that the traditional analog AGC is difficult to quickly and accurately control the wide range of an input radio frequency signal, and further estimates the communication environment. In short, the traditional analog AGC method is difficult to achieve balance in the aspects of large dynamic range, response time, control precision, hardware resource consumption and the like, and under the conditions of large dynamic signal and stable output of intermediate frequency amplitude, the traditional analog AGC method can not meet the requirements of large dynamic and quick digital AGC. The conventional analog AGC has mainly the following drawbacks: the AGC is not enough in establishing and releasing time, can not be established and released quickly within a set time, and can not be controlled from the reference gain control quantity when the signal is changed next time, so that the communication quality is poor, and the anti-interference performance is also affected to a certain extent; the AGC establishing, releasing and stabilizing time cannot be adjusted under fixed waveforms, the AGC time solidified by an analog device is not necessarily the optimal time, the flexibility is poor, and the requirements of various waveforms on the AGC time difference are not considered easily; the analog AGC circuit is complex, occupies larger volume and weight of a module, and has relatively high cost; the gain control amount of the channel cannot be accurately realized, and cannot be accurately estimated.
The digital AGC technology can solve the problems of the analog AGC, realizes the establishment and release time of the AGC within a controllable specified range, ensures definite link gain control, improves the communication reliability, and is used as a technical reserve to develop and support for new-generation communication equipment. The AGC state of the device can also judge the strength of useful signals, evaluate the external communication conditions and help the baseband signal processing related functions such as squelch processing. Compared with the analog AGC, the digital AGC has the main function of the feedback section realized by the digital section, so that the AGC control can be realized more easily. The digital implementation method generally utilizes a lookup table mapping method, combines an A/D device and a programmable device according to priority judgment, samples an input signal, and realizes gain stabilization according to a conversion relation lookup table after quantization. The method for realizing the digital AGC is realized in a DSP or an FPGA. The general approach to a digital AGC loop is to compare the output of a matched filter with a user defined reference level value to produce an error signal, which is loop filtered to produce an adjustment signal that is sent to a multiplier to control the output of a tracking buffer. In the implementation, the mean square value of the I, Q paths is calculated by the multiplier DSP48 in the FPGA, the accumulation of the mean square value is completed by the accumulator, the number of accumulated sample points directly determines the corresponding speed of control adjustment, and the corresponding speed is slow due to the fact that the accumulation length is too long, and the change of signals cannot be followed; too short a length, however, may cause inaccurate estimated power values and too large fluctuations, which may cause a decrease in control accuracy.
There are two AGC loops in the prior art, one based on a linear relationship of the received signal to a reference value and the other based on a logarithmic relationship of the two. An AGC algorithm based on a linear relationship of symbol amplitudes is implemented in the linearity of the AGC loop filter, which calculates the level value of the AGC output and compares it to a fixed threshold value to produce an error signal that is multiplied by a weighting factor a less than 1 to control the steady state response of the circuit. One fundamental problem with this conventional approach is that: if the steady state response of the AGC loop is not controlled by a but by a change in the level of the input signal, an unstable attack and release time will result, resulting in a degradation of the receiver performance. Conventional digital AGC requires exponential and logarithmic operations in the amplitude estimation and gain factor adjustment sections and is not easy to implement in hardware. It is often necessary to use a look-up table to approximate the logarithmic and exponential operations, and the size of the ROM used in the look-up table limits the dynamic range of the AGC.
In practical communication, the main purpose of radio frequency control is to ensure the linearity of the radio frequency front-end circuit to the circuit before the intermediate frequency numerical control attenuation, and then to adjust the rationality of circuit gain distribution. Because the dynamic range of the input signal is large, and the detection dynamic range of the radio frequency detector is limited, the radio frequency signal is not easy to accurately detect, and is easily influenced by the interference signal, so that false detection is caused. Only large step adjustments of the general range can be made, small changes in the signal are not. In addition, the following reality needs to be accepted: when a large signal or a strong interference signal is input, the radio frequency circuit carries out large step attenuation and the radio station falls; but the linearity of the channel and the signal demodulation capability at small signal inputs must be guaranteed. Due to the influence of factors such as propagation loss, slow fading of the topographic shadow and the like, the tracking time is set by reasonably selecting elements, and the envelope amplitude change of the received signal can be tracked and adjusted rapidly, but false detection and omission detection of the received signal are easy to occur in burst communication. The common analog AGC circuit is divided into two types, namely a PIN diode electrically-tunable attenuator AGC and a VGA variable gain amplifier AGC. The diode has the defects of poor consistency, sensitivity to temperature change and the like, so that the debugging of the AGC circuit is complex and oscillation is easy to generate. While digital AGC enables automatic gain control for radio frequency input signals over a large dynamic range. The VGA variable gain amplifier AGC has poor noise performance when cascaded, and is easy to generate irreducible error codes. In the measuring instruments such as a digital intermediate frequency spectrum analyzer and a digital intermediate frequency receiver, the ADC device has errors such as quantization noise, aperture jitter, differential nonlinear distortion, thermal noise and the like, so that the input dynamic range and the effective output bit number of the ADC can be reduced, thereby limiting the input dynamic range of the instrument and being difficult to meet the design requirement. The signal strength at the receiver input varies and fluctuates significantly due to fading phenomena in the satellite signal in spatial propagation. In order to ensure the normal operation of the subsequent demodulation and processing, an Automatic Gain Control (AGC) system for analog signals is generally added to the front end of the receiver, so that the receiver automatically adapts to the change of the input signals, and the normal operation of the communication system is ensured. However, the front-end analog AGC only controls the signal level within the access range of the AD, so that the digital signal is processed normally, and the back-end needs to keep the different signals at a certain power. General method of digital AGC loop AGC compares the output of a matched filter with a user defined reference level value to produce an error signal, which is loop filtered to produce an adjustment signal, which is sent to a multiplier to control the output of a tracking buffer. There are two AGC loops, one based on a linear relationship of the received signal to a reference value and the other based on a logarithmic relationship of the two. The loop calculates the level value of the AGC output and compares it to a fixed threshold value to produce an error signal that is multiplied by a weighting factor a (less than 1) to control the steady state response of the circuit. A fundamental problem with this conventional approach is that if the steady state response of the AGC loop is not controlled by a, but by the level change of the input signal, an unstable attack and release time will be caused, resulting in a deterioration of the receiver performance. Since the loop time constant is proportional to the order of the signal amplitude, the loop has a small number of times, resulting in overshoot. This shows that if the signal has a small amplitude transition, the AGC loop has a large number of times, thus taking a long time to reach steady state, resulting in a slow system response.
Disclosure of Invention
In order to overcome the defect that the traditional analog AGC can not control the wide-range input radio frequency signals quickly and accurately, the invention provides a control method of a large dynamic quick digital AGC with stable circuit, high convergence speed, large dynamic range and short response time aiming at the defects in the prior art.
The digital AGC control circuit divides the channel link of the receiver into two sections of a radio frequency part and an intermediate frequency part, in the radio frequency part channel link, the radio frequency signal received by the receiver passes through a front-end first frequency hopping filter amplifying circuit, after being attenuated by a first digital control attenuator Gain according to the requirement, the intermediate frequency signal is output through twice mixing, the intermediate frequency signal passes through a second frequency hopping filter amplifying circuit to be amplified by Gain, after being attenuated by a second step or superposition, the intermediate frequency signal is converted into analog voltage by a coupling detection operational amplifier, then the analog signal is converted into a digital signal sent into an FPGA by an analog-to-digital converter AD, the digital AGC radio frequency detection module adjusts the radio frequency attenuation and the intermediate frequency attenuation in real time to output radio frequency detection according to ADC output, and the control attenuation is primarily determined by using the radio frequency detection result, so that the link Gain is roughly adjusted; meanwhile, the control attenuation quantity is sent into a radio frequency peak value detection module and a peak value latching module to enter a radio frequency gain control module to form a first parallel radio frequency feedback loop for controlling a radio frequency circuit, the first parallel radio frequency feedback loop is sent into an intermediate frequency filter to carry out intermediate frequency filtering after the second frequency conversion is completed through a second frequency converter, a fourth-stage digital control attenuator, a first video graphic array VGA, a second video graphic array VGA and an analog-to-digital converter ADC are sequentially connected in series, the fourth-stage digital control attenuator, the first video graphic array VGA, the second video graphic array VGA and the analog-to-digital converter ADC are sent into an intermediate frequency peak value detection module and an average power detection module through a 1-to-2+Q-to-2 module, the second parallel AGC loop for intermediate frequency gain control is formed by the intermediate frequency gain control module, and the result of the radio frequency detection is combined with the detection result of an intermediate frequency AD, and whether the radio frequency detection result is an interference signal or a useful signal is judged; the radio frequency detection part performs gain control of a radio frequency link by a first parallel radio frequency feedback loop, and performs rough adjustment and double-loop adjustment on the link gain respectively; the second parallel AGC feedback loop controls the intermediate frequency AGC by using the intermediate frequency detection and AD sampling result through the intermediate frequency gain control module, fine adjusts the link, rapidly controls the rear end numerical control attenuator through intermediate frequency AD detection, adjusts the intermediate frequency output signal intensity within the AD dynamic range, controls the output power of the digital automatic gain control loop, and completes the whole digital automatic gain control.
Compared with the traditional analog AGC method, the method has the following beneficial effects:
aiming at the problems of longer response time, longer control processing time, poor real-time feedback loop and the like of the traditional analog AGC method, the invention divides a channel link into a radio frequency part and an intermediate frequency part, the two loops are respectively adjusted, the radio frequency detection part carries out gain control of the radio frequency link, and the link gain is roughly adjusted; the intermediate frequency detection and AD sampling result is used for controlling the intermediate frequency AGC and fine adjusting the link. The radio frequency part preliminarily determines the control attenuation amount by utilizing the radio frequency detection result, controls the radio frequency circuit, combines the radio frequency detection result with the detection result of the intermediate frequency AD, and judges whether the radio frequency detection result is an interference signal or a useful signal. The attenuation control of the radio frequency part is used for controlling the link linearity in front of the intermediate frequency circuit; and the intermediate frequency part is used for rapidly controlling the rear-end numerical control attenuator through intermediate frequency AD detection and adjusting the intensity of an intermediate frequency output signal within the AD dynamic range. AGC signal power can be accurately obtained through the mean square value of quadrature I/Q (i.e. I2+Q2), the gain of the variable gain amplifier is automatically adjusted, real-time amplification/attenuation of an input signal is realized, automatic gain control with a large dynamic range can be provided, and the dynamic range of a real-time numerical control AGC circuit and the precision of the whole system are improved. The circuit is stable, the convergence speed is high, the dynamic range is large, and the response time is short.
Aiming at the problem that the input signal of the detector is in a nonlinear region due to large signal peak variation, when the input power of the detector is in the nonlinear region, the power is firstly adjusted to the linear region, and then the link gain is monitored in real time according to ADC sampling. The dual rings are adopted to respectively adjust, the radio frequency detection part carries out gain control of a radio frequency link, and coarse adjustment is carried out on the link; the intermediate frequency detection and AD sampling result is used for controlling the intermediate frequency AGC and fine-tuning the link. Coarse and fine adjustment of gain are realized through two-stage numerical control gain amplification/attenuation, and further, the numerical control gain amplification/attenuation is accurately realized. When the amplitude of the signal input into the variable gain amplifier is increased, the feedback loop controls the gain of the variable gain amplifier to be reduced according to a certain relation; when the gain is reduced, the gain is increased according to a certain relation. Thus, no matter the intensity of the input signal, the output signal with basically constant level can be obtained after AGC amplification, thereby ensuring the dynamic range of the system. The complex control requirements can be easily realized by using a digital signal processing technology, and the method has the advantages of rapid convergence, accurate steady-state response and the like. Compared with analog AGC, the method reduces debugging difficulty and enhances stability, convergence and accuracy.
The invention adopts the monitoring intermediate frequency signal to control the radio frequency AGC and the intermediate frequency AGC, so that the input radio frequency signal has a large dynamic range, and the intermediate frequency amplitude can be stably and constantly output. The digital AGC is adopted for control, the signal is quickly adjusted in real time, the response time is short, the speed is greatly improved, the control speed is high, and the dynamic range of the channel module is improved. Through the adjustment of the steps, the stable output of the intermediate frequency amplitude is ensured in a large dynamic range of the input signal. The following functions can be realized: the radio frequency AGC and the intermediate frequency AGC are controlled by monitoring the intermediate frequency signal, so that the intermediate frequency amplitude can be stably and constantly output when the dynamic range of the input radio frequency signal is large. The digital AGC is adopted for control, the signal is quickly adjusted in real time, the response time is short, the speed is greatly improved, the control speed is high, and the dynamic range of the channel module is improved. Compared with the traditional analog AGC control technology, the adopted quick digital AGC technology can accurately compensate gain, the response time is short, and the control circuit is simple and clear. And can provide accurate linear amplification with little temperature influence. Compared with the traditional AGC method, the method has the advantages of faster response time, higher efficiency and better real-time performance, and can adapt to a large dynamic range.
The invention uses the intermediate frequency wave detection and AD sampling result to control the intermediate frequency AGC, and fine-tune the link. Compared with the traditional AGC control technology, the method can realize stable output of the intermediate frequency signal more quickly and accurately by detecting the intermediate frequency amplitude. Compared with the traditional analog AGC, the method has lower calculation complexity and is convenient for the hardware implementation of the FPGA. The defects of the traditional AGC are overcome to a certain extent, and the control loop is realized by adopting the FPGA, so that the response and convergence speed are faster, and the performance is more stable, thereby simplifying the debugging of the electronic equipment and improving the receiving capacity of the electronic equipment and the working performance of the receiver. Experiments show that the method can quickly respond to a large dynamic received signal. The hardware test results show that when the amplitude of the received signal varies widely, the average amplitude fluctuation range of the output signal can be made very small in the continuous and burst communication modes. The linearity of the receiver can be improved, so that the signal distortion is minimum and the error rate is minimum; the dynamic range of the receiver is widened as much as possible, so that the receiver has higher adaptability and higher anti-interference capability.
Radio frequency detection characteristics: the advantages are low gain of the front stage, small influence of noise on detection output, low delay and short response time when the signal is large; the defect that the detection bandwidth is larger than the signal bandwidth, and the power statistics value comprises out-of-band interference signals of the front-end radio frequency filter; the detection output is weak or no output when the signal is small due to the influence of the detection performance. The FPGA-based large dynamic range digital AGC relies on a nonlinear function to control the output power of a digital automatic gain control loop, so that the whole loop can reach a steady state in a shorter time.
Intermediate frequency detection characteristics: the detector has the advantages that the detection output power is equal to the ADC inlet power, and the detection signal can be considered as a useful signal as the signal is subjected to intermediate frequency filtering, and the detection bandwidth is equal to the useful signal bandwidth; the disadvantage is that the front-stage gain is high, so that the detection output power is greatly influenced by noise when a small signal is caused; when the signal is large, the intermediate frequency signal is saturated and compressed greatly, and the detection power is smaller than the actual power; the delay is large when the device is far away from a radio frequency inlet and is used for adjusting the first-stage numerical control attenuator and the second-stage numerical control attenuator, and the loop delay is large. Compared with the traditional linear digital AGC, the convergence speed is high, and the dynamic range is large. By comparing the above, the invention has higher result precision and faster response compared with the analog AGC method.
Drawings
Fig. 1 is a schematic diagram of the AGC control principle of the present invention for large dynamic fast digital automatic gain control;
fig. 2 is a detailed control flow diagram of the digital AGC rf detection module rf AGC amplitude;
fig. 3 is a detailed control flow chart of the intermediate frequency AGC amplitude;
the invention is further described below with reference to the drawings and the detailed description.
Detailed Description
See fig. 1. According to the invention, a digital AGC control circuit divides a channel link of a receiver into a radio frequency part and an intermediate frequency part, in the radio frequency part channel link, a radio frequency signal received by the receiver is amplified by a front-end first frequency hopping filter amplifying circuit, is attenuated by a first digital control attenuator Gain according to the need to realize first step or superposition attenuation, is subjected to two-time mixing to output an intermediate frequency signal, is amplified by a second frequency hopping filter amplifying circuit to realize second step or superposition attenuation, is converted into an analog voltage by a coupling detection operational amplifier, is converted into a digital signal fed into an FPGA by an analog-to-digital converter AD, and is output by a digital AGC radio frequency detection module according to ADC, the radio frequency attenuation and the intermediate frequency attenuation are adjusted in real time to output radio frequency detection, the control attenuation is primarily determined by using a radio frequency detection result, and the link Gain is roughly adjusted; meanwhile, the control attenuation quantity is sent into a radio frequency peak value detection module and a peak value latching module to enter a radio frequency gain control module to form a first parallel radio frequency feedback loop for controlling a radio frequency circuit, the first parallel radio frequency feedback loop is sent into an intermediate frequency filter to carry out intermediate frequency filtering after the second frequency conversion is completed through a second frequency converter, a fourth-stage digital control attenuator, a first video graphic array VGA, a second video graphic array VGA and an analog-to-digital converter ADC are sequentially connected in series, the fourth-stage digital control attenuator, the first video graphic array VGA, the second video graphic array VGA and the analog-to-digital converter ADC are sent into an intermediate frequency peak value detection module and an average power detection module through a 1-to-2+Q-to-2 module, the second parallel AGC loop for intermediate frequency gain control is formed by the intermediate frequency gain control module, and the result of the radio frequency detection is combined with the detection result of an intermediate frequency AD, and whether the radio frequency detection result is an interference signal or a useful signal is judged; the radio frequency detection part performs gain control of a radio frequency link by a first parallel radio frequency feedback loop, and performs rough adjustment and double-loop adjustment on the link gain respectively; the second parallel AGC feedback loop controls the intermediate frequency AGC by using the intermediate frequency detection and AD sampling result through the intermediate frequency gain control module, fine adjusts the link, rapidly controls the rear end numerical control attenuator through intermediate frequency AD detection, adjusts the intermediate frequency output signal intensity within the AD dynamic range, controls the output power of the digital automatic gain control loop, and completes the whole digital automatic gain control.
When the input power of the detector is in a nonlinear region, the digital AGC radio frequency detection module firstly adjusts the power to a linear region, and then monitors the link gain in real time according to ADC sampling. The intermediate frequency peak value detection module and the average power detection module are respectively adjusted by double rings, the radio frequency detection part performs gain control of a radio frequency link, and coarse adjustment is performed on the link.
The model of the first-stage numerical control attenuator and the second-stage numerical control attenuator is SX361EE, and the first-stage numerical control attenuator and the second-stage numerical control attenuator are used for controlling the attenuation of radio frequency signals; the model of the third-stage numerical control attenuator and the fourth-stage numerical control attenuator is SX361EE, and the third-stage numerical control attenuator and the fourth-stage numerical control attenuator are used for controlling the attenuation of intermediate frequency signals; the second-stage digital attenuator is connected with a mixer and is used for secondary frequency conversion, and the model adopted is SFM308K; the model of the detector for detecting the amplitude signals of the radio frequency and intermediate frequency signals is HKPC58012SIP; the model for AD conversion is YA16S125 for converting the detected signal into a digital signal; the FPGA is used for converting the radio frequency signals into intermediate frequency; the radio frequency peak detection module adopts JFM7K325T-FFG900 to complete the signal acquisition and control functions.
See fig. 2. As can be seen from the flow chart of the detailed control of the amplitude of the radio frequency AGC, when the input power of the radio frequency detection signal through the port corresponding to the intensity of the radio frequency detection signal is less than or equal to P1, the digital AGC radio frequency detection module adjusts the intermediate frequency according to the output of the ADC without adjusting the radio frequency, and the AGC is ended; when the input power P of the radio frequency detection signal is more than or equal to P1 and less than or equal to P2, the digital AGC radio frequency detection module waits for the detection result of intermediate frequency adjustment, and when the intermediate frequency adjustment is less than or equal to P3, the AGC adjustment is finished, but the output after the intermediate frequency adjustment is still more than or equal to P4, the radio frequency is required to attenuate S3, and then the AGC is finished; when the input power of the radio frequency detection signal is more than or equal to P2, the radio frequency attenuation S1, the intermediate frequency attenuation S2, and the output after the intermediate frequency adjustment is less than or equal to P3, the digital AGC radio frequency detection module finishes the AGC adjustment, but the output after the intermediate frequency adjustment is more than or equal to P3, the digital control attenuator needs the radio frequency to attenuate S3, the AGC is finished after the intermediate frequency adjustment, and the whole radio frequency AGC control process is completed.
See fig. 3. As can be seen from the flow chart of the detailed control of the amplitude of the intermediate frequency AGC, when the amplitude of the intermediate frequency detection signal of the digital AGC radio frequency detection module is less than or equal to P1, the intermediate frequency gain control module does not adjust the intermediate frequency, and the AGC is finished; when the input power of the intermediate frequency detection signal is more than or equal to P1 and less than or equal to P2, the numerical control attenuator attenuates the intermediate frequency S1, and the AGC adjustment is finished; when the input power of the intermediate frequency detection signal is more than or equal to P2, the intermediate frequency is attenuated by S2, and when the intermediate frequency amplitude is less than or equal to P1, the AGC is ended; when the intermediate frequency amplitude falls between P1 and P2, the numerical control attenuator attenuates the intermediate frequency again S1, and the AGC is finished; after the intermediate frequency is attenuated S2, the detection power of the digital AGC radio frequency detection module is still more than or equal to P2, the digital control attenuator attenuates the intermediate frequency amplitude again S3, and when the intermediate frequency amplitude is less than or equal to P1, the AGC is finished; and when the intermediate frequency amplitude is between P1 and P2, the numerical control attenuator attenuates the intermediate frequency again S1, and the AGC is finished, so that the whole intermediate frequency AGC control process is completed.
While the present invention has been described in detail with reference to the above embodiments, those skilled in the art will recognize that various changes may be made in the embodiments without departing from the spirit and scope of the invention, and in light of the foregoing, the disclosure set forth in the specification should not be construed as limiting the invention.
Claims (10)
1. A large dynamic rapid digital automatic gain control AGC method is characterized in that: the digital AGC control circuit divides a channel link of a receiver into a radio frequency part and an intermediate frequency part, in the radio frequency part channel link, a radio frequency signal received by the receiver is amplified by a front-end first frequency hopping filter amplifying circuit, the radio frequency signal is amplified by a second frequency hopping filter amplifying circuit, attenuated first step or superposition attenuation is realized by a first-stage numerical control attenuator according to the requirement, attenuated second step or superposition attenuation is realized by a second-stage numerical control attenuator according to the requirement, an intermediate frequency signal is output by two times of mixing, the intermediate frequency signal is converted into an analog voltage by a coupling detection operational amplifier, the analog signal is converted into a digital signal sent into an FPGA by an analog-to-digital converter AD, the digital AGC radio frequency detection module outputs radio frequency detection by real-time adjustment of radio frequency attenuation and intermediate frequency attenuation, the control attenuation is preliminarily determined by using the radio frequency detection result, and the link gain is roughly adjusted; meanwhile, the control attenuation quantity is sent into a radio frequency peak value detection module and a peak value latching module to enter a radio frequency gain control module to form a first parallel radio frequency feedback loop for controlling a radio frequency circuit, the first parallel radio frequency feedback loop is sent into an intermediate frequency filter to carry out intermediate frequency filtering after the second frequency conversion is completed through a second frequency converter, a fourth-stage digital control attenuator, a first video graphic array VGA, a second video graphic array VGA and an analog-to-digital converter ADC are sequentially connected in series, the fourth-stage digital control attenuator, the first video graphic array VGA, the second video graphic array VGA and the analog-to-digital converter ADC are sent into an intermediate frequency peak value detection module and an average power detection module through a 1-to-2+Q-to-2 module, the second parallel AGC loop for intermediate frequency gain control is formed by the intermediate frequency gain control module, and the result of the radio frequency detection is combined with the detection result of an intermediate frequency AD, and whether the radio frequency detection result is an interference signal or a useful signal is judged; the radio frequency detection part performs gain control of a radio frequency link by a first parallel radio frequency feedback loop, and performs rough adjustment and double-loop adjustment on the link gain respectively; the second parallel AGC feedback loop controls the intermediate frequency AGC by using the intermediate frequency detection and AD sampling result through the intermediate frequency gain control module, fine adjusts the link, rapidly controls the rear end numerical control attenuator through intermediate frequency AD detection, adjusts the intermediate frequency output signal intensity within the AD dynamic range, controls the output power of the digital automatic gain control loop, and completes the whole digital automatic gain control.
2. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: when the input power of the detector is in a nonlinear region, the digital AGC radio frequency detection module firstly adjusts the power to a linear region, and then monitors the link gain in real time according to ADC sampling.
3. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: the intermediate frequency peak value detection module and the average power detection module are respectively adjusted by double rings, the radio frequency detection part performs gain control of a radio frequency link, and coarse adjustment is performed on the link.
4. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: the model of the first-stage numerical control attenuator and the second-stage numerical control attenuator is SX361EE, and the first-stage numerical control attenuator and the second-stage numerical control attenuator are used for controlling the attenuation of radio frequency signals; the model of the third-stage numerical control attenuator and the fourth-stage numerical control attenuator is SX361EE, and the third-stage numerical control attenuator and the fourth-stage numerical control attenuator are used for controlling the attenuation of intermediate frequency signals; the second stage of digital attenuator is connected with a mixer for secondary frequency conversion, and the model adopted is SFM308K.
5. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: the model of the detector for detecting the amplitude signals of the radio frequency and intermediate frequency signals is HKPC58012SIP; model number YA16S125 for AD conversion for converting the detected signal into a digital signal; the FPGA is used for converting the radio frequency signals to intermediate frequency; the radio frequency peak detection module adopts JFM7K325T-FFG900 to complete the signal acquisition and control functions.
6. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: when the input power of the radio frequency detection signal through the port corresponding to the radio frequency detection signal intensity is less than or equal to P1, the digital AGC radio frequency detection module adjusts the intermediate frequency according to the output of the ADC without adjusting the radio frequency, and the AGC is finished.
7. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: when the input power P of the radio frequency detection signal is more than or equal to P1 and less than or equal to P2, the digital AGC radio frequency detection module waits for the detection result of intermediate frequency adjustment, and when the intermediate frequency adjustment is less than or equal to P3, the AGC adjustment is finished, but the output after the intermediate frequency adjustment is still more than or equal to P4, the radio frequency is required to attenuate S3, and then the AGC is finished.
8. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: when the input power of the radio frequency detection signal is more than or equal to P2, the radio frequency attenuation S1, the intermediate frequency attenuation S2, and the output after the intermediate frequency adjustment is less than or equal to P3, the digital AGC radio frequency detection module finishes the AGC adjustment, but the output after the intermediate frequency adjustment is more than or equal to P3, the digital control attenuator needs the radio frequency to attenuate S3, the AGC is finished after the intermediate frequency adjustment, and the whole radio frequency AGC control process is completed.
9. The large dynamic fast digital automatic gain control AGC method according to claim 1, wherein: when the amplitude of the intermediate frequency detection signal is less than or equal to P1, the intermediate frequency gain control module does not adjust the intermediate frequency, and the AGC is finished; when the input power of the intermediate frequency detection signal is more than or equal to P1 and less than or equal to P2, the numerical control attenuator attenuates the intermediate frequency S1, and the AGC adjustment is finished; when the input power of the intermediate frequency detection signal is more than or equal to P2, the intermediate frequency is attenuated by S2, and when the intermediate frequency amplitude is less than or equal to P1, the AGC is ended; when the intermediate frequency amplitude falls between P1 and P2, the numerical control attenuator attenuates the intermediate frequency again S1, and the AGC is finished.
10. The large dynamic fast digital automatic gain control AGC method of claim 9 wherein: after the intermediate frequency is attenuated S2, the detection power of the digital AGC radio frequency detection module is still more than or equal to P2, the digital control attenuator attenuates the intermediate frequency amplitude again S3, and when the intermediate frequency amplitude is less than or equal to P1, the AGC is finished; and when the intermediate frequency amplitude is between P1 and P2, the numerical control attenuator attenuates the intermediate frequency again S1, and the AGC is finished, so that the whole intermediate frequency AGC control process is completed.
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| CN115189703A (en) * | 2022-05-24 | 2022-10-14 | 北京零壹空间电子有限公司 | Automatic gain control method and device |
| CN115913417B (en) * | 2023-01-07 | 2023-06-23 | 成都川美新技术股份有限公司 | Device and method for improving detection range and precision of radio frequency power detector |
| CN116318212A (en) * | 2023-01-09 | 2023-06-23 | 中国电子科技集团公司第十研究所 | Automatic gain control circuit and control method for ultrashort wave radio station |
| CN116209049B (en) * | 2023-05-04 | 2023-06-30 | 中国人民解放军国防科技大学 | Full-link signal power self-adaptive optimization method for intelligent channel simulator |
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