CN210297644U

CN210297644U - Receiving frequency converter

Info

Publication number: CN210297644U
Application number: CN201921929017.XU
Authority: CN
Inventors: 陈永彤; 胡罗林; 张华彬; 何栋梁; 唐超; 王耀兴; 鲜亮
Original assignee: Chengdu Phase Lock Electronic Technology Co Ltd
Current assignee: Chengdu Phase Lock Electronic Technology Co Ltd
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2020-04-10
Anticipated expiration: 2029-11-08

Abstract

The utility model discloses a receiving frequency converter, including two the same receiving frequency conversion channels, receiving frequency conversion channel includes that the merit divides filter module, frequency conversion module and two the same intermediate frequency automatic gain control modules, the input that the merit divides filter module inserts all the way radio frequency signal to divide radio frequency signal merit into two the way, the signal transmission after all the way merit divides to frequency conversion module after frequency conversion module transmits all the way intermediate frequency automatic gain control module to carry out the automatic gain control after export; the other path of the signal after power division is directly transmitted to the other path of the intermediate frequency automatic gain control module for automatic gain control and then output, and the frequency converter receives the radio frequency and the intermediate frequency signal synthesized by the receiving front end component in two paths, so that the bandwidth selection and automatic gain control amplification of the intermediate frequency signal and the down-conversion and automatic gain control amplification of the radio frequency signal are completed. The frequency converter receives the radio frequency and the intermediate frequency signals which are synthesized by the receiving front end component in two paths, and completes the bandwidth selection and the automatic gain control amplification of the intermediate frequency signals.

Description

Receiving frequency converter

Technical Field

The utility model belongs to the technical field of communication, specifically speaking relates to a receive converter.

Background

With the development of communication technology, the application of frequency conversion channels in civil and military fields is becoming wider and wider, and frequency conversion signals become key components of radio communication and radar systems. The modern wireless communication receiving frequency conversion channel needs to have high sensitivity and high linearity, and the requirement on the isolation between channels in the same frequency conversion component is higher and higher, the isolation between the channels influences the interference on signals in the channels, and the greater interference influences the integrity of the signals to cause the loss of the signals.

The invention patent with application number 201710041659.5 discloses an ultra-wideband multichannel receiving frequency conversion assembly, which comprises a control unit, an external clock unit, a calibration source unit, a first local oscillator unit, a second local oscillator unit, a third local oscillator unit, a clock signal source unit and a receiving frequency conversion link unit; the whole structure is divided into two layers, wherein the upper layer comprises a control unit, an external clock unit and a calibration source unit; the lower layer is a first local oscillation unit, a second local oscillation unit, a third local oscillation unit, a clock signal source unit and a receiving frequency conversion link unit. The design of double layers, sub-cavities and high integration level of LTCC is adopted, so that the small-size and multifunctional design concept is guaranteed, the connection relation is adopted at present, when the corresponding function is realized, the link routing is short, the insertion loss is small, the connection between modules is convenient and reliable, and the debugging is simple and convenient due to the design of sub-modules.

The document discloses a receiving frequency conversion link unit, which adopts three times of frequency conversion to realize the down conversion of ultra-wideband radio frequency signals, and adopts a process to achieve the purpose of size reduction, and the link structure is complex.

SUMMERY OF THE UTILITY MODEL

To foretell not enough among the prior art, the utility model provides a receive converter, this converter receive the radio frequency and the intermediate frequency signal after the two tunnel synthesis of front end subassembly, accomplish the bandwidth selection and the automatic gain control of intermediate frequency signal and amplify and radio frequency signal's down conversion and automatic gain control amplify.

In order to achieve the above object, the utility model discloses a solution is: a receiving frequency converter comprises two identical receiving frequency conversion channels, wherein each receiving frequency conversion channel comprises a power division filtering module, a frequency conversion module and two identical intermediate frequency automatic gain control modules; the other path of the signal after power division is directly transmitted to the other path of the intermediate frequency automatic gain control module for automatic gain control and then output, and the frequency converter receives the radio frequency and the intermediate frequency signal synthesized by the receiving front end component in two paths, so that the bandwidth selection and automatic gain control amplification of the intermediate frequency signal and the down-conversion and automatic gain control amplification of the radio frequency signal are completed.

The power division filtering module comprises a first power divider, the input end of the first power divider is connected with a radio frequency signal, the first power divider divides the power of the radio frequency signal into two paths of signals, one path of signal is connected with a first band-pass filter, the first band-pass filter performs band-pass filtering on the signal after power division, the other path of signal is connected with a sixth band-pass filter, and the sixth band-pass filter performs band-pass filtering on the signal after power division.

The frequency conversion module comprises a first amplifier, a second amplifier and a frequency conversion module, wherein the first amplifier is connected with the first band-pass filter and used for amplifying the accessed radio-frequency signals; the high-pass filter is connected with the output end of the first amplifier and is used for carrying out high-pass filtering on the signal after the first amplification and filtering low-frequency clutter in the signal; the first frequency mixer is connected with the output end of the high-pass filter and mixes the high-pass filtered signal with the first local oscillator signal; the first attenuator is connected with the output end of the first mixer and is used for performing first-stage attenuation on the mixed signal; the second band-pass filter is connected with the output end of the first attenuator and is used for performing band-pass filtering on the signal after the first-stage attenuation; the second amplifier is connected with the output end of the second band-pass filter and used for amplifying the signal subjected to band-pass filtering; the first low-pass filter is connected with the output end of the second amplifier and is used for low-pass filtering the signal amplified for the second time; the second frequency mixer is connected with the output end of the first low-pass filter and used for mixing the low-pass filtered signal with a second local oscillator signal; the second attenuator is connected with the output end of the second mixer and is used for carrying out second-stage attenuation on the mixed signal; the second low-pass filter is connected with the output end of the second attenuator and is used for low-pass filtering the signal after the second attenuation; the third amplifier is connected with the output end of the second low-pass filter and used for amplifying the signal subjected to the second low-pass filtering; the third attenuator is connected with the output end of the third amplifier and is used for attenuating the data amplified for the third time; the fourth amplifier is connected with the output end of the third attenuator and is used for amplifying the signal after the third attenuation; and the third band-pass filter is connected with the output end of the fourth amplifier and used for performing band-pass filtering on the fourth amplified signal, the output of the third band-pass filter is used as the output of the frequency conversion channel, the frequency conversion module obtains the required intermediate frequency through secondary down-conversion, the link gain distribution is balanced, and the matching degree between all the devices is good.

The intermediate frequency automatic gain control module comprises a first numerical control attenuator, wherein the input end of the first numerical control attenuator is connected with an intermediate frequency signal and attenuates the intermediate frequency signal; the fifth amplifier is connected with the output end of the first numerical control attenuator and is used for amplifying the signal after the first-stage attenuation; the second digital control attenuator is connected with the output end of the fifth amplifier and is used for attenuating the amplified signal; the sixth amplifier is connected with the output end of the second digital controlled attenuator and is used for amplifying the signal after the second-stage attenuation; the third numerical control attenuator is connected with the output end of the sixth amplifier and is used for attenuating the amplified signal; the seventh amplifier is connected with the output end of the third numerical control attenuator and is used for amplifying the signal after the third-stage attenuator; the eighth amplifier is connected with the output end of the seventh amplifier and is used for amplifying the amplified signal again; the fixed end of the first single-pole double-throw switch is connected with the output end of the eighth amplifier; the fourth band-pass filter is connected with the first moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the first moving end; the fifth band-pass filter is connected with the second moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the second moving end; the first moving end of the second single-pole double-throw switch is connected with the output end of the fourth band-pass filter, and the second moving end of the second single-pole double-throw switch is connected with the output end of the fifth band-pass filter; the fixed end of the second single-pole double-throw switch is connected with the intermediate-frequency output end; the input end of the first numerical control attenuator of the middle-frequency automatic gain control module is connected with the sixth band-pass filter, the input end of the first numerical control attenuator of the other middle-frequency automatic gain control module is connected with the output end of the third band-pass filter, the middle-frequency automatic gain control module further comprises an FPGA control panel, the output end of the FPGA control panel is respectively connected with the control ends of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator of each gain channel to control the attenuation of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator, the middle-frequency automatic gain control module further comprises a detection control channel, the detection control channel comprises a coupler, the input end of the coupler is connected with the immovable end of the second single-pole double-throw switch, and divides the video signal into two paths, and is connected with the middle-frequency output end all the way, another way is connected with fourth numerical control attenuator, exports the wave detector after carrying out fourth level attenuation, and the wave detector exports the AD converter after amplifying the signal, and the AD converter is transmitted the FPGA control panel to the signal conversion after amplifying the wave detector, first numerical control attenuator, second numerical control attenuator and third numerical control attenuator step by step be 1dB, the maximum attenuation value is 31.5dB, cascades through tertiary attenuator, and the maximum attenuation range is 94.5dB, the wave detector adopt the linear AD8310 of logarithm, automatic gain control module of intermediate frequency can accurately carry out automatic gain control, has great dynamic range and can effectively restrain the receiving channel stray.

The frequency conversion module also comprises a first local oscillator and a second local oscillator, wherein a first local oscillator signal generated by the first local oscillator is divided into 2 paths by the local oscillator power divider, each path of signal is input to a first frequency mixer which receives a frequency conversion channel and is mixed with a radio frequency signal, a second local oscillator signal generated by the second local oscillator is divided into 2 paths by the local oscillator power divider, each path of signal is input to a second frequency mixer which receives a frequency conversion channel and is mixed with the radio frequency signal.

The first local oscillator and the second local oscillator have the same structure and respectively comprise a frequency source, the frequency source outputs radio frequency signals, and a seventh band-pass filter is connected with the output end of the frequency source and performs band-pass filtering on the radio frequency signals; the local oscillator power divider is connected with the output end of the seventh band-pass filter and divides the signal power after band-pass filtering into two paths; the third low-pass filter is connected with the output end of the ninth amplifier, performs low-pass filtering on the amplified signal, and outputs the filtered radio-frequency signal to the frequency mixer; and the frequency sources of the first local oscillator and the second local oscillator generate radio frequency signals with different frequencies.

The utility model has the advantages that:

(1) the frequency converter receives the radio frequency and the intermediate frequency signals which are synthesized by the receiving front end component in two paths, and completes the bandwidth selection and the automatic gain control amplification of the intermediate frequency signals and the down-conversion and the automatic gain control amplification of the radio frequency signals.

Drawings

FIG. 1 is a block diagram of the frequency converter of the present invention;

fig. 2 is the receiving frequency conversion channel link diagram of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

a receiving frequency converter comprises two identical receiving frequency conversion channels, wherein each receiving frequency conversion channel comprises a power division filtering module, a frequency conversion module and two identical intermediate frequency automatic gain control modules; the other path of the signal after power division is directly transmitted to the other path of the intermediate frequency automatic gain control module for automatic gain control and then output, and the frequency converter receives the radio frequency and the intermediate frequency signal synthesized by the receiving front end component in two paths, so that the bandwidth selection and automatic gain control amplification of the intermediate frequency signal and the down-conversion and automatic gain control amplification of the radio frequency signal are completed.

The frequency conversion module comprises a first amplifier, a second amplifier and a frequency conversion module, wherein the first amplifier is connected with the first band-pass filter and used for amplifying the accessed radio-frequency signals; the high-pass filter is connected with the output end of the first amplifier and is used for carrying out high-pass filtering on the signal after the first amplification and filtering low-frequency clutter in the signal; the first frequency mixer is connected with the output end of the high-pass filter and mixes the high-pass filtered signal with the first local oscillator signal; the first attenuator is connected with the output end of the first mixer and is used for performing first-stage attenuation on the mixed signal; the second band-pass filter is connected with the output end of the first attenuator and is used for performing band-pass filtering on the signal after the first-stage attenuation; the second amplifier is connected with the output end of the second band-pass filter and used for amplifying the signal subjected to band-pass filtering; the first low-pass filter is connected with the output end of the second amplifier and is used for low-pass filtering the signal amplified for the second time; the second frequency mixer is connected with the output end of the first low-pass filter and used for mixing the low-pass filtered signal with a second local oscillator signal; the second attenuator is connected with the output end of the second mixer and is used for carrying out second-stage attenuation on the mixed signal; the second low-pass filter is connected with the output end of the second attenuator and is used for low-pass filtering the signal after the second attenuation; the third amplifier is connected with the output end of the second low-pass filter and used for amplifying the signal subjected to the second low-pass filtering; the third attenuator is connected with the output end of the third amplifier and is used for attenuating the data amplified for the third time; the fourth amplifier is connected with the output end of the third attenuator and is used for amplifying the signal after the third attenuation; and the third band-pass filter is connected with the output end of the fourth amplifier and used for performing band-pass filtering on the fourth amplified signal, the output of the third band-pass filter is used as the output of a frequency conversion channel, the gain of the frequency conversion channel is 34dB, the component obtains the required intermediate frequency through two-stage down-conversion, the frequency conversion relation is IF (IF) -RF-LO, the link gain distribution is balanced, and the matching degree between all devices is good. The device with good amplitude-frequency characteristics is selected, so that the gain flatness is favorably improved, for example, the amplifier flatness is good, and the filter in-band ripple is small.

The intermediate frequency automatic gain control module comprises a first numerical control attenuator, wherein the input end of the first numerical control attenuator is connected with an intermediate frequency signal and attenuates the intermediate frequency signal; the fifth amplifier is connected with the output end of the first numerical control attenuator and is used for amplifying the signal after the first-stage attenuation; the second digital control attenuator is connected with the output end of the fifth amplifier and is used for attenuating the amplified signal; the sixth amplifier is connected with the output end of the second digital controlled attenuator and is used for amplifying the signal after the second-stage attenuation; the third numerical control attenuator is connected with the output end of the sixth amplifier and is used for attenuating the amplified signal; the seventh amplifier is connected with the output end of the third numerical control attenuator and is used for amplifying the signal after the third-stage attenuator; the eighth amplifier is connected with the output end of the seventh amplifier and is used for amplifying the amplified signal again; the fixed end of the first single-pole double-throw switch is connected with the output end of the eighth amplifier; the fourth band-pass filter is connected with the first moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the first moving end; the fifth band-pass filter is connected with the second moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the second moving end; the first moving end of the second single-pole double-throw switch is connected with the output end of the fourth band-pass filter, and the second moving end of the second single-pole double-throw switch is connected with the output end of the fifth band-pass filter; the fixed end of the second single-pole double-throw switch is connected with the intermediate-frequency output end; the input end of the first numerical control attenuator of the middle-frequency automatic gain control module is connected with the sixth band-pass filter, the input end of the first numerical control attenuator of the other middle-frequency automatic gain control module is connected with the output end of the third band-pass filter, the middle-frequency automatic gain control module further comprises an FPGA control panel, the output end of the FPGA control panel is respectively connected with the control ends of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator of each gain channel to control the attenuation of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator, the middle-frequency automatic gain control module further comprises a detection control channel, the detection control channel comprises a coupler, the input end of the coupler is connected with the immovable end of the second single-pole double-throw switch, and divides the video signal into two paths, and is connected with the middle-frequency output end all the way, another way is connected with fourth numerical control attenuator, exports the wave detector after carrying out fourth level attenuation, and the wave detector exports the AD converter after amplifying the signal, and the AD converter is transmitted the FPGA control panel to the signal conversion after amplifying the wave detector, first numerical control attenuator, second numerical control attenuator and third numerical control attenuator step by step be 1dB, the maximum attenuation value is 31.5dB, cascades through tertiary attenuator, and the maximum attenuation range is 94.5dB, the wave detector adopt the linear AD8310 of logarithm, automatic gain control module of intermediate frequency can accurately carry out automatic gain control, has great dynamic range and can effectively restrain the receiving channel stray. The FPGA control panel can adopt the control panel adopted by the existing communication radar, and mainly adopts the function of controlling the attenuation of the numerical control attenuator by the FPGA control panel in the existing communication radar.

When automatic gain control is carried out, the numerical value of the detector is obtained for multiple times within a time constant, the numerical value is subjected to average calculation to obtain an average value, the average value is compared with a result required to be output, and the difference value obtained through comparison is used for setting an automatic gain link.

Inside the FPGA control board, the reference value V0 is subtracted from the AD sampling value V1 at the time T1 to obtain the current error value corresponding to the current gain Ga (which can be negative) required to be increased, the current error value enters a loop accumulator and is added with the AGC gain value G0 at the last time T0 to obtain the current required gain value G, the value is multiplied by an adjusting coefficient F to serve as the target gain value G1 of the adjustment at the time, the value required to be adjusted by the current attenuator is calculated according to G1 and is converted into attenuation codes, the action of the attenuator is controlled, and the adjustment is completed. And (3) circulating for a plurality of times until the error voltage is 0 (or within the control precision range).

And according to different time constants, the adjustment speed can be controlled by changing the adjustment coefficient F. The coefficient is preferably selected not to be adjusted too many times, and it is recommended to use ten or more times when 3ms is used.

The time of each cycle is adjusted by AD sampling smoothing filter (average value), and the time of each cycle is controlled to be about 0.3ms (ensuring that the minimum time constant also has 10 cycle approximation processes).

When the difference between G0 and G1 is within 0.5dB (minimum step), no adjustment is required. When the time constant is large, the factor F is small, the value of G1 may change very little each time, there is no need to adjust the attenuation value each time, and the adjustment is made each time the minimum step is accumulated.

AGC is realized by cascading three-stage numerical control attenuators of intermediate frequency. The step of the intermediate frequency numerical control attenuator of each stage is 1dB, and the maximum attenuation value is 31.5 dB. After three-stage cascade, the maximum attenuation range can reach 94.5dB, and the index requires the AGC dynamic range: greater than 70dB, precision: 1 dB.

The first local oscillator and the second local oscillator have the same structure and respectively comprise a frequency source, the frequency source outputs radio frequency signals, and a seventh band-pass filter is connected with the output end of the frequency source and performs band-pass filtering on the radio frequency signals; the local oscillator power divider is connected with the output end of the seventh band-pass filter and divides the signal power after band-pass filtering into two paths; the third low-pass filter is connected with the output end of the ninth amplifier, performs low-pass filtering on the amplified signal, and outputs the filtered radio-frequency signal to the frequency mixer; and the frequency sources of the first local oscillator and the second local oscillator generate radio frequency signals with different frequencies. The multiple channels share the same local oscillator, the local oscillator source signal and the signal in the frequency conversion channel, mutual crosstalk can occur, the reverse isolation of the two-stage fifth amplifier is 30dB, the local oscillator power divider adopts an active local oscillator power divider, the crosstalk can reach 20dB when the crosstalk signal passes through the frequency mixer, the isolation of the 2 power divider to the crosstalk signal is 20dB, the low-pass filter is 20dB of isolation to the crosstalk, and finally when the crosstalk signal is in crosstalk to another channel, the signal is about-130 dBm, the crosstalk is small, and the influence on the signal in the channel is small.

The above-mentioned embodiments only express the specific embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.

Claims

1. A receiving transducer, characterized by: the receiving frequency conversion channel comprises a power dividing filtering module, a frequency conversion module and two identical intermediate frequency automatic gain control modules, wherein the input end of the power dividing filtering module is connected with a radio frequency signal and divides the radio frequency signal into two paths, and the signal subjected to power dividing is transmitted to the frequency conversion module, is subjected to frequency conversion by the frequency conversion module and then is transmitted to the intermediate frequency automatic gain control module for automatic gain control and then is output; and the other path of signal after power division is directly transmitted to the other path of intermediate frequency automatic gain control module for automatic gain control and then output.

2. The receiving transducer of claim 1, wherein: the power division filtering module comprises a first power divider, the input end of the first power divider is connected with a radio frequency signal, the first power divider divides the power of the radio frequency signal into two paths of signals, one path of signal is connected with a first band-pass filter, the first band-pass filter performs band-pass filtering on the signal after power division, the other path of signal is connected with a sixth band-pass filter, and the sixth band-pass filter performs band-pass filtering on the signal after power division.

3. The receiving transducer of claim 2, wherein: the frequency conversion module comprises a first amplifier, a second amplifier and a frequency conversion module, wherein the first amplifier is connected with the first band-pass filter and used for amplifying the accessed radio-frequency signals; the high-pass filter is connected with the output end of the first amplifier and is used for carrying out high-pass filtering on the signal after the first amplification and filtering low-frequency clutter in the signal; the first frequency mixer is connected with the output end of the high-pass filter and mixes the high-pass filtered signal with the first local oscillator signal; the first attenuator is connected with the output end of the first mixer and is used for performing first-stage attenuation on the mixed signal; the second band-pass filter is connected with the output end of the first attenuator and is used for performing band-pass filtering on the signal after the first-stage attenuation; the second amplifier is connected with the output end of the second band-pass filter and used for amplifying the signal subjected to band-pass filtering; the first low-pass filter is connected with the output end of the second amplifier and is used for low-pass filtering the signal amplified for the second time; the second frequency mixer is connected with the output end of the first low-pass filter and used for mixing the low-pass filtered signal with a second local oscillator signal; the second attenuator is connected with the output end of the second mixer and is used for carrying out second-stage attenuation on the mixed signal; the second low-pass filter is connected with the output end of the second attenuator and is used for low-pass filtering the signal after the second attenuation; the third amplifier is connected with the output end of the second low-pass filter and used for amplifying the signal subjected to the second low-pass filtering; the third attenuator is connected with the output end of the third amplifier and is used for attenuating the data amplified for the third time; the fourth amplifier is connected with the output end of the third attenuator and is used for amplifying the signal after the third attenuation; and the third band-pass filter is connected with the output end of the fourth amplifier and is used for performing band-pass filtering on the fourth amplified signal, and the output of the third band-pass filter is used as the output of the frequency conversion channel.

4. The receiving transducer of claim 3, wherein: the intermediate frequency automatic gain control module comprises a first numerical control attenuator, wherein the input end of the first numerical control attenuator is connected with an intermediate frequency signal and attenuates the intermediate frequency signal; the fifth amplifier is connected with the output end of the first numerical control attenuator and is used for amplifying the signal after the first-stage attenuation; the second digital control attenuator is connected with the output end of the fifth amplifier and is used for attenuating the amplified signal; the sixth amplifier is connected with the output end of the second digital controlled attenuator and is used for amplifying the signal after the second-stage attenuation; the third numerical control attenuator is connected with the output end of the sixth amplifier and is used for attenuating the amplified signal; the seventh amplifier is connected with the output end of the third numerical control attenuator and is used for amplifying the signal after the third-stage attenuator; the eighth amplifier is connected with the output end of the seventh amplifier and is used for amplifying the amplified signal again; the fixed end of the first single-pole double-throw switch is connected with the output end of the eighth amplifier; the fourth band-pass filter is connected with the first moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the first moving end; the fifth band-pass filter is connected with the second moving end of the first single-pole double-throw switch and used for performing band-pass filtering on the signal accessed through the second moving end; the first moving end of the second single-pole double-throw switch is connected with the output end of the fourth band-pass filter, and the second moving end of the second single-pole double-throw switch is connected with the output end of the fifth band-pass filter; the fixed end of the second single-pole double-throw switch is connected with the intermediate-frequency output end; the input end of the first numerical control attenuator of one path of intermediate frequency automatic gain control module is connected with the sixth band-pass filter, and the input end of the first numerical control attenuator of the other path of intermediate frequency automatic gain control module is connected with the output end of the third band-pass filter.

5. The receiving transducer of claim 4, wherein: the frequency conversion module also comprises a first local oscillator and a second local oscillator, wherein a first local oscillator signal generated by the first local oscillator is divided into 2 paths by the local oscillator power divider, each path of signal is input to a first frequency mixer which receives a frequency conversion channel and is mixed with a radio frequency signal, a second local oscillator signal generated by the second local oscillator is divided into 2 paths by the local oscillator power divider, each path of signal is input to a second frequency mixer which receives a frequency conversion channel and is mixed with the radio frequency signal.

6. The receiving transducer of claim 5, wherein: the first local oscillator and the second local oscillator have the same structure and respectively comprise a frequency source, the frequency source outputs radio frequency signals, and a seventh band-pass filter is connected with the output end of the frequency source and performs band-pass filtering on the radio frequency signals; the local oscillator power divider is connected with the output end of the seventh band-pass filter and divides the signal power after band-pass filtering into two paths; the third low-pass filter is connected with the output end of the ninth amplifier, performs low-pass filtering on the amplified signal, and outputs the filtered radio-frequency signal to the frequency mixer; and the frequency sources of the first local oscillator and the second local oscillator generate radio frequency signals with different frequencies.

7. The receiving transducer of claim 4, wherein: the intermediate frequency automatic gain control module further comprises an FPGA control panel, wherein the output end of the FPGA control panel is respectively connected with the control ends of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator of each gain channel to control the attenuation of the first numerical control attenuator, the second numerical control attenuator and the third numerical control attenuator.

8. The receiving transducer of claim 7, wherein: the intermediate frequency automatic gain control module still include detection control channel, detection control channel include the coupler, the input of coupler is connected with the motionless end of second single-pole double-throw switch to divide the video signal merit into two tunnel, be connected with the intermediate frequency output all the way, another tunnel is connected with fourth numerical control attenuator, carry out the fourth level and attenuate the back and export the detector, the detector is exported the AD converter after amplifying the signal, the AD converter is converted the digital signal transmission to the FPGA control panel with the signal conversion after the detector amplifies.

9. The receive converter of claim 8, wherein: the stepping of the first numerical control attenuator, the stepping of the second numerical control attenuator and the stepping of the third numerical control attenuator are 1dB, the maximum attenuation value is 31.5dB, the maximum attenuation range is 94.5dB through cascade connection of three stages of attenuators, and the detector adopts a log-linear AD 8310.