CN112713868B

CN112713868B - Network supervision system

Info

Publication number: CN112713868B
Application number: CN202110016060.2A
Authority: CN
Inventors: 李伟超; 齐云飞; 李琴; 张柳琪; 赵海霞
Original assignee: Hubei Central China Technology Development Of Electric Power Co ltd
Current assignee: Hubei Central China Technology Development Of Electric Power Co ltd
Priority date: 2021-01-07
Filing date: 2021-01-07
Publication date: 2023-09-22
Anticipated expiration: 2041-01-07
Also published as: CN112713868A

Abstract

The invention relates to a network supervision system, a carrier receiving circuit receives network signals by adopting a tunable receiver, outputs the network signals after frequency selection amplification or frequency selection and controllable notch amplification, a second-stage frequency mixing circuit carries out difference frequency operation on the output signals of the carrier receiving circuit and reference carrier signals by adopting a first-stage frequency mixing circuit to generate difference frequency signals, the difference frequency signals are subjected to feedback frequency modulation to enhance stability, then enter the second-stage frequency mixing circuit and the reference carrier signals to carry out sum frequency operation to generate correct and stable carrier signals to a monitoring host, a small frequency offset compensation circuit acquires the output signals of the second-stage frequency mixing circuit, when the frequency offset is smaller, the output signals are fed back to the second-stage frequency mixing circuit and the first-stage frequency mixing circuit step by step, the output signals of the first-stage frequency offset correction circuit are acquired and fed back to the tunable receiver after being converted into voltage, and the resonance frequency of the tunable receiver is corrected, so that the network supervision system is automatically suitable for different carrier frequency bands. The problem that the frequency offset of the network signal influences the accuracy of the received signal is effectively solved.

Description

Network supervision system

Technical Field

The invention relates to the technical field of network supervision, in particular to a network supervision system.

Background

With the frequent occurrence of network security accidents, the national importance of network security is also continuously deepened. In the prior art, a network analysis platform is mainly adopted for supervision, specifically, a real-time acquisition network signal (a network signal transmitted through connection media such as a cable, a twisted pair, an optical fiber, a microblog, a carrier or satellite communication) is transmitted to a monitoring host, the monitoring host analyzes a received signal, however, the signal transmission is affected by noise, interference of other signals, doppler effect and the like, network signals transmitted by different connection media have different carrier frequency ranges, if a receiving frequency range regulated by a receiver is not suitable for the carrier frequency ranges of different connection media, the network signal can generate a frequency offset phenomenon, the accuracy of the received signal is affected, and therefore, the carrier frequency deviation of the received network signal needs to be corrected.

Disclosure of Invention

Aiming at the situation, in order to overcome the defects of the prior art, the invention aims to provide a network supervision system which effectively solves the problem that the frequency offset of network signals influences the accuracy of received signals.

The technical scheme is that the frequency offset correction circuit comprises a carrier receiving circuit, a secondary mixing circuit, a small frequency offset compensation circuit and a large frequency offset correction circuit, and is characterized in that the carrier receiving circuit receives a network signal by adopting a tunable receiver, the network signal is amplified by frequency selection or frequency selection and is amplified by a controllable notch, the secondary mixing circuit carries out difference frequency operation on an output signal of the carrier receiving circuit and a reference carrier signal by adopting a first-stage mixing circuit to generate a difference frequency signal, the difference frequency signal is subjected to feedback frequency modulation to enhance stability, then enters the second-stage mixing circuit and the reference carrier signal to carry out sum frequency operation to generate a correct and stable carrier signal to a monitoring host, the small frequency offset compensation circuit acquires the output signal of the secondary mixing circuit, when the frequency offset is small, the secondary mixing circuit and the first-stage mixing circuit acquire the output signal, the large frequency offset correction circuit feeds back to the tunable receiver after converting the output signal into voltage, corrects the resonance frequency of the tunable receiver to achieve the purpose of automatically adapting to different carrier frequency bands.

The beneficial effects of the invention are as follows: the method comprises the steps that a tunable receiver is adopted to receive network signals, the network signals are amplified by frequency selection or frequency selection and controllable notch amplification and then output, the phenomenon that a frequency offset can lead to attenuation of tuning received signals is utilized, the amplified output signals are output to be direct current signals through a diode average value detector, when the direct current signal amplitude is normal, a triode Q7 is conducted, +5V supplies power to a secondary frequency mixing circuit, when the direct current signal amplitude is low, the controllable notch filter is used for notch frequency selection, namely, the triode Q1 is not used for amplifying the signals, the secondary frequency mixing circuit is used for carrying out difference frequency operation on carrier receiving circuit output signals and reference carrier signals by a first stage frequency mixing circuit, a difference frequency signal is generated, a frequency selection network is arranged, the frequency selection is fed back to the grid electrode of a field effect transistor Q2, so that stability of the output signals of the first stage frequency mixing circuit is enhanced, and then the second stage frequency mixing circuit and the reference carrier signals are subjected to sum frequency operation, and correct and stable carrier signals are generated to a monitoring host; the method comprises the steps of collecting output signals of a secondary mixing circuit through a frequency selection circuit, feeding back the output signals to a base electrode of a triode Q4 in the secondary mixing circuit through a high-pass filter formed by a capacitor C12 and an inductor L8 when the frequency deviation is small, feeding back the output signals to a grid electrode of a field effect tube Q2 in the primary mixing circuit through a high-pass filter formed by a capacitor C13 and an inductor L9 when the frequency deviation is large, carrying out frequency deviation compensation, enabling the secondary mixing circuit to generate stable carrier signals to a monitoring host, converting the difference frequency signals into voltages through the output signals of the primary mixing circuit, feeding back the voltages to a tunable receiver, correcting the resonance frequency of the tunable receiver, adapting to network signal frequency bands transmitted by connecting media, and achieving automatic adaptation to different carrier frequency bands.

Drawings

Fig. 1 is a schematic diagram of the circuit connection of the present invention.

Detailed Description

The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the accompanying fig. 1. The following embodiments are described in detail with reference to the drawings.

Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

A network supervision system comprises a carrier receiving circuit, a secondary mixing circuit, a small frequency offset compensation circuit and a large frequency offset correction circuit, wherein the carrier receiving circuit adopts a tunable receiver to receive network signals, a variable capacitor CP1 and a variable capacitor BD1 which are connected in series are used for adjusting the frequency to be in resonance with the frequency band of the received network signals, the frequency is selected by a frequency selecting network, a controllable trap is trapped, then a triode Q1 and a resistor R4-resistor R6 are used for frequency selecting and amplifying or frequency selecting and outputting after controllable trap amplifying, the secondary mixing circuit adopts a first-stage mixing circuit formed by a field effect tube Q2, a variable capacitor CP 3-variable capacitor CP7, a capacitor C5 and an inductor L5 to perform difference frequency operation on the output signals of the carrier receiving circuit and reference carrier signals to generate difference frequency signals, the frequency-selecting network composed of triode Q3, capacitor C6 and C18, inductor L6 and resistor R7 is set to select frequency and then feed back to grid electrode of field effect tube Q2 to enhance stability of output signal of first stage mixing circuit, then the second stage mixing circuit composed of triode Q4, capacitor C8, C9, C18, variable capacitor CP8 and inductor L7 and reference carrier signal are fed into to make sum frequency operation, difference frequency + sum frequency is set to raise anti-interference property, correct and stable carrier signal is produced to monitoring host, the small frequency offset compensation circuit collects output signal of second stage mixing circuit by means of frequency-selecting circuit, when frequency offset is small (when national standard connection medium allows frequency offset to be plus or minus 5%), high pass filter composed of capacitor C12 and inductor L8 feeds back to base electrode of triode Q4 in second stage mixing circuit to make frequency offset compensation, when frequency offset is large (when allowing frequency offset to be plus or minus 10%, the high-pass filter composed of a capacitor C13 and an inductor L9 is fed back to the grid electrode of the field effect tube Q2 in the first-stage mixing circuit to carry out frequency deviation compensation so that the second-stage mixing circuit generates stable carrier signals to the monitoring host, the large frequency deviation correction circuit collects output signals of the first-stage mixing circuit, difference frequency signals are converted into voltages through triodes Q6 and Q7, a resistor R10, an electrolytic capacitor E5 and a diode D2 and then fed back to the tunable receiver, the resonance frequencies of the tunable receiver are corrected, the signals are matched with network signal frequency bands transmitted by connecting media, the signals are automatically matched with different carrier frequency bands, the second-stage mixing circuit generates correct carrier signals, the output signals of the first-stage mixing circuit are collected and fed back to the tunable receiver after being converted into voltages, the resonance frequencies of the tunable receiver are corrected, and the signals are automatically matched with different carrier frequency bands, so that the second-stage mixing circuit generates correct carrier signals.

Based on the above scheme, the carrier receiving circuit receives a network signal by adopting a tunable receiver composed of a transformer T1, a variable capacitor CP1 and a variable diode BD1 which are connected in series, the variable capacitor CP1 and the variable diode BD1 which are connected in series adjust the frequency to resonate with the frequency band of the received network signal (network signal transmitted by connecting media such as cables, twisted pairs, optical fibers, microblogs, carrier waves or satellite communication, etc.), the variable capacitor CP2 and the inductor L1 which are connected in series select the frequency with a frequency selection network composed of a capacitor C1 and an inductor L2 which are connected in parallel, a controllable trap composed of a resistor R1, a resistor R2, a capacitor C2 and a capacitor C3, an inductor L3 and a thyristor VTL1, then the frequency is input into a triode Q1, a resistor R4-resistor R6 to perform frequency selection amplification or frequency selection and controllable trap amplification, and then output, in particular, the phenomenon that the tuned received signal is attenuated by utilizing frequency offset, the collector output signal of the triode Q1 is output as a direct current signal through a diode average value detector formed by a capacitor C15-capacitor C17 and diodes D1 and D3, when the direct current signal amplitude is normal, the triode Q7 is conducted, +5V is used for supplying power to a secondary mixing circuit, when the direct current signal amplitude is low, the photoelectric coupler OP1 is conducted, the thyristor VTL1 is conducted, the controllable trap is used for trapping a signal after trapping and frequency selection, namely the triode Q1 is not used for amplifying the signal, the device comprises a transformer T1, one end of a primary coil of the transformer T1 is connected with a network signal of a communication terminal, the other end of the primary coil of the transformer T1 is connected with the ground, one end of a secondary coil of the transformer T1 is connected with one end of a variable capacitor CP1, the other end of the variable capacitor CP1 is connected with the negative electrode of the variable capacitor BD1, the positive electrode of the variable capacitor BD1 is connected with the ground, the other end of the secondary coil of the transformer T1 is connected with the ground, the middle end of the secondary coil of the transformer T1 is connected with one end of a variable capacitor CP2, the other end of the variable capacitor CP2 is respectively connected with one end of an inductor L1, the other end of the inductor L1 is respectively connected with one end of a grounding capacitor C1, one end of a grounding inductor L1 and one end of a resistor R1, the other end of the resistor R1 is respectively connected with one end of a capacitor C2 and one end of a resistor R2, the other end of the resistor R2 is respectively connected with one end of a capacitor C3 and the base electrode of a triode Q1, the other end of the capacitor C2 is respectively connected with the other end of the capacitor C3 and one end of the inductor L3, the other end of the inductor L3 is connected with the anode of a thyristor VTL1, the cathode of the thyristor VTL1 is connected with the ground, the emitter of the triode Q1 is respectively connected with one end of a resistor R4 and one end of a grounding resistor R5, the other end of the resistor R4 is connected with a power supply +15V, the collector of the triode Q1 is respectively connected with one end of a grounding resistor R6, one end of a grounding capacitor C4 and one end of a capacitor C15, the collector of the triode Q1 outputs signals to a carrier receiving circuit, the other end of the capacitor C15 is respectively connected with the anode of a diode D1 and the cathode of a diode D3, the cathode of the diode D1 is respectively connected with one end of the grounding capacitor C16 and one end of a resistor R6, the other end of the resistor R6 is connected with the base of a triode Q8, the collector of the triode Q8 is connected with a power supply +5V, the anode of the diode D3 is respectively connected with one end of the grounding capacitor C17 and the pin 2 of a photoelectric coupler OP1, the pin 1 of the photoelectric coupler OP1 is connected with a power supply +0.7V, the pin 4 of the photoelectric coupler OP1 is connected with a power supply +5V, and the pin 3 of the photoelectric coupler OP1 is connected with the control electrode of a thyristor VTL 1.

On the basis of the scheme, the second-stage mixer circuit adopts a first-stage mixer circuit formed by a field effect transistor Q2, a variable capacitor CP 3-variable capacitor CP7, a capacitor C5 and an inductor L5 to perform difference frequency operation on an output signal of a carrier receiving circuit and a reference carrier signal to generate a difference frequency signal, wherein a frequency selecting network formed by a triode Q3, capacitors C6 and C18, an inductor L6 and a resistor R7 is arranged to select frequency and feed back to a grid electrode of the field effect transistor Q2, so as to enhance the stability of the output signal of the first-stage mixer circuit, then the second-stage mixer circuit and the reference carrier signal formed by the triode Q4, the capacitors C8, C9 and C18, the variable capacitor CP8 and the inductor L7 are subjected to sum frequency operation, a correct and stable carrier signal is generated to a monitoring host, the grid electrode of the field effect transistor Q2 is respectively connected with the output signal of the carrier receiving circuit through the variable capacitor CP3 and the variable capacitor CP4, the reference carrier signal is connected with the grid electrode of the other end of the field effect transistor Q2, the grid electrode of the field effect transistor Q2 is connected with one end of the variable capacitor CP5, the other end of the variable capacitor C6 and the other end of the capacitor C7 is connected with the drain electrode of the capacitor C6 and the drain electrode of the variable capacitor C7 of the triode Q7, the drain electrode of the triode Q4 is respectively connected with the other end of the variable capacitor C6 and the drain electrode of the capacitor C7 of the variable capacitor C7, and the drain electrode of the triode Q7 is connected with the variable capacitor C7 is connected with the drain electrode of the variable capacitor C3 and the variable capacitor C7, the other end of the variable capacitor C3 is connected with the other end of the variable capacitor C3 and the drain electrode is connected with the ground capacitor C3, the other end of the capacitor C8 is respectively connected with one end of the capacitor C18, one end of the grounding capacitor C9, one end of the grounding inductor L7 and the base electrode of the triode Q4, the other end of the capacitor C18 is connected with a reference carrier signal, the emitter electrode of the triode Q4 is connected with a power supply-10V through a resistor R8, and the collector electrode of the triode Q4 is connected to a monitoring host through a grounding variable capacitor CP 1.

On the basis of the scheme, the small frequency offset compensation circuit collects output signals of the secondary mixing circuit through a frequency selection circuit formed by a triode Q5, a resistor R9, a capacitor C10 and a capacitor C11 (the bandwidth of the frequency selection circuit and the bandwidth of the output signals of the secondary mixing circuit are described herein, so that the secondary mixing circuit can analyze the frequency band of the output signals of the secondary mixing circuit), when the frequency offset is small (when a national standard connection medium allows positive and negative 5% of the frequency band deviation), the small frequency offset compensation circuit feeds back to a base electrode of a triode Q4 in the secondary mixing circuit through a high-pass filter formed by a capacitor C12 and an inductor L8, performs frequency offset compensation, and feeds back to a grid electrode of a field effect transistor Q2 in the primary mixing circuit through a high-pass filter formed by a capacitor C13 and an inductor L9, so that the secondary mixing circuit can generate stable carrier signals to a monitoring host, wherein one end of the capacitor C10 is connected with one end of the secondary mixing circuit, the other end of the capacitor C10 is respectively connected with a base electrode of the triode Q5, one end of the resistor C9, one end of the other end of the capacitor C9 is connected with the collector electrode of the capacitor C9, one end of the other end of the capacitor C9 is respectively connected with the other end of the triode Q2, and the other end of the capacitor C14 is connected with the collector electrode of the capacitor C12 and the other end of the capacitor C12 is connected with the other end of the triode Q2; the large frequency offset correction circuit collects output signals of the first-stage mixing circuit, difference frequency signals are converted into voltages through triodes Q6 and Q7, a resistor R10, an electrolytic capacitor E5 and a diode D2 and then fed back to the tunable receiver, resonance frequencies of the tunable receiver are corrected, the difference frequency signals are adaptive to network signal frequency bands transmitted by connecting media (cables, twisted pairs, optical fibers, microblogs, carrier waves or satellite communication and the like), the difference frequency signals are automatically adaptive to different carrier wave frequency bands, the two-stage mixing circuit generates correct carrier wave signals, the correct carrier wave signals comprise the base electrode of a triode Q6 connected with the other end of an inductor L5, the collector electrode of the triode Q6 is respectively connected with the negative electrode of an electrolytic capacitor E5 and one end of the resistor R10, the other end of the resistor R10 is connected with a power supply +5V, the positive electrode of the electrolytic capacitor E5 is respectively connected with the positive electrode of the diode D2 and the emitting electrode of the triode Q7, the base electrode of the triode Q7, the negative electrode of the diode D2 and the emitting electrode of the triode Q6 are grounded, and the collector electrode of the triode Q7 is connected with the negative electrode of a variable capacitance diode BD 1.

When the invention is particularly used, the carrier receiving circuit receives network signals by adopting a tunable receiver consisting of a transformer T1, a variable capacitor CP1 and a variable capacitor BD1 which are connected in series, the variable capacitor CP1 and the variable capacitor BD1 which are connected in series adjust the frequency to be in resonance with the frequency band of the received network signals, the frequency is selected by a frequency selecting network consisting of a variable capacitor CP2 and an inductor L1 which are connected in series and a capacitor C1 and an inductor L2 which are connected in parallel, a controllable trap consisting of a resistor R1, a resistor R2, a capacitor C2 and a capacitor C3, an inductor L3 and a thyristor VTL1 is trapped, then the carrier receiving signals are subjected to frequency selecting amplification or frequency selecting and frequency selecting amplification and then output after entering a triode Q1 and a resistor R4-resistor R6, then the carrier receiving signals and reference carrier signals are subjected to difference frequency operation by entering a first-stage mixing circuit consisting of a field effect transistor Q2, a variable capacitor CP3 and a capacitor C5 and an inductor L5, generating a difference frequency signal, wherein a frequency-selecting network composed of a triode Q3, a capacitor C6 and a capacitor C18, an inductor L6 and a resistor R7 is arranged for frequency selection and then fed back to the grid electrode of a field effect transistor Q2 so as to enhance the stability of an output signal of a first-stage frequency mixing circuit, then the difference frequency signal enters a second-stage frequency mixing circuit composed of a triode Q4, a capacitor C8, a capacitor C9, a capacitor C18, a variable capacitor CP8 and an inductor L7 and a reference carrier signal for summation operation, a correct and stable carrier signal is generated and fed to a monitoring host, a small frequency offset compensation circuit is arranged, a second-stage frequency mixing circuit output signal is acquired through a frequency-selecting circuit composed of a triode Q5, a resistor R9, a capacitor C10 and a capacitor C11, when the frequency offset is small, the difference frequency is fed back to the base electrode of a triode Q4 in the second-stage frequency mixing circuit through a high-pass filter composed of a capacitor C12 and an inductor L8 for frequency offset compensation, and a high-pass filter consisting of a capacitor C13 and an inductor L9 is fed back to the grid electrode of the field effect tube Q2 in the first-stage mixing circuit to carry out frequency deviation compensation, so that the second-stage mixing circuit generates stable carrier signals to a monitoring host, a large frequency deviation correction circuit is arranged, the output signals of the first-stage mixing circuit are collected, the difference frequency signals are converted into voltages through triodes Q6 and Q7, a resistor R10, an electrolytic capacitor E5 and a diode D2 and then fed back to a tunable receiver, the resonance frequency of the tunable receiver is corrected, and the frequency deviation correction circuit is suitable for network signal frequency bands transmitted by connecting mediums (cables, twisted pairs, optical fibers, microblogs, carrier waves or satellite communication and the like) to achieve the purpose of automatically adapting to different carrier frequency bands, so that the second-stage mixing circuit generates correct carrier signals, the frequency deviation of the network signals is solved, and the accuracy problem of received signals is affected.

Claims

1. The network supervision system comprises a carrier receiving circuit, a secondary mixing circuit, a small frequency offset compensation circuit and a large frequency offset correction circuit, and is characterized in that the carrier receiving circuit receives network signals by adopting a tunable receiver, the network signals are amplified by frequency selection or frequency selection and controlled notch amplification and then output, the secondary mixing circuit carries out difference frequency operation on output signals of the carrier receiving circuit and reference carrier signals by adopting a first-stage mixing circuit to generate difference frequency signals, the difference frequency signals are subjected to feedback frequency modulation to enhance stability, then enter the second-stage mixing circuit and the reference carrier signals to carry out sum frequency operation to generate correct and stable carrier signals to a monitoring host, the small frequency offset compensation circuit acquires output signals of the secondary mixing circuit, the small frequency offset compensation circuit feeds back to the second-stage mixing circuit and the first-stage mixing circuit step by step, the large frequency offset correction circuit acquires output signals of the first-stage mixing circuit, and feeds back to the tunable receiver after converting the output signals into voltages, corrects the resonance frequency of the tunable receiver to achieve the purpose of automatically adapting to different carrier frequency bands;

the carrier receiving circuit comprises a transformer T1, one end of a primary coil of the transformer T1 is connected with a communication terminal network signal, the other end of the primary coil of the transformer T1 is connected with the ground, one end of a secondary coil of the transformer T1 is connected with one end of a variable capacitor CP1, the other end of the variable capacitor CP1 is connected with the negative electrode of a variable capacitor BD1, the positive electrode of the variable capacitor BD1 is connected with the ground, the other end of the secondary coil of the transformer T1 is connected with the ground, the middle end of the secondary coil of the transformer T1 is connected with one end of a variable capacitor CP2, the other end of the variable capacitor CP2 is respectively connected with one end of an inductor L1, the other end of the inductor L1 is respectively connected with one end of a grounding capacitor C1, one end of a grounding inductor L1 and one end of a resistor R1, the other end of a resistor R2 is respectively connected with one end of a capacitor C2 and the base of a triode Q1, the other end of the capacitor C2 is respectively connected with the other end of the capacitor C3 and one end of the inductor L3, the other end of the inductor L3 is connected with the anode of the thyristor VTL1, the cathode of the thyristor VTL1 is connected with the ground, the emitter of the triode Q1 is respectively connected with one end of the resistor R4 and one end of the grounding resistor R5, the other end of the resistor R4 is connected with the power +15V, the collector of the triode Q1 is respectively connected with one end of the grounding resistor R6, one end of the grounding capacitor C4 and one end of the capacitor C15, the collector of the triode Q1 is a carrier receiving circuit output, the other end of the capacitor C15 is respectively connected with the anode of the diode D1 and the cathode of the diode D3, the cathode of the diode D1 is respectively connected with one end of the grounding capacitor C16 and one end of the resistor R6, the other end of the resistor R6 is connected with the base of the triode Q8, the collector of the triode Q8 is connected with the power +5V, the anode of the diode D3 is respectively connected with one end of the grounding capacitor C17, pin 2 of the photoelectric coupler OP1, pin 1 of the photoelectric coupler OP1 is connected with a power supply +0.7V, pin 4 of the photoelectric coupler OP1 is connected with a power supply +5V, and pin 3 of the photoelectric coupler OP1 is connected with a control electrode of the thyristor VTL 1;

the secondary mixing circuit comprises a field effect transistor Q2, wherein a grid electrode of the field effect transistor Q2 is respectively connected with a carrier receiving circuit to output signals and reference carrier signals through a variable capacitor CP3 and a variable capacitor CP4, a grid electrode of the field effect transistor Q2 is connected with one end of a grounded variable capacitor CP5, a source electrode of the field effect transistor Q1 is connected with the ground, a drain electrode of the field effect transistor Q2 is respectively connected with one end of an inductor L4, one end of the inductor L5 and one end of a grounded variable capacitor CP6 and one end of a variable capacitor CP7, the other end of the inductor L4 and one end of a grounded capacitor C5 are connected with an emitter electrode of a triode Q7, the other end of the inductor L5 is respectively connected with one end of the variable capacitor CP7 and one end of the capacitor C8, the other end of the capacitor C7 is respectively connected with one end of the triode Q8, the other end of the capacitor C7 is respectively connected with one end of a resistor R7 and one base electrode of the triode Q3, a collector electrode of the triode Q3 is respectively connected with one end of the inductor L6 and the other end of the resistor R7 and one end of the capacitor C18, the other end of the inductor L6 is connected with one end of the ground, one end of the capacitor C18 is connected with the ground capacitor C4 and the ground of the triode Q4 is connected with one end of the ground, and the base electrode of the triode Q4 is connected with the ground, the capacitor Q4 is connected with the ground, the ground and the base of the capacitor Q4 is connected with the ground capacitor C4 and the base of the capacitor C4 is connected with the ground;

the small frequency offset compensation circuit comprises a capacitor C10, one end of the capacitor C10 is connected with a collector of a triode Q4, the other end of the capacitor C10 is respectively connected with a base electrode of a triode Q5, one end of a resistor R9 and one end of a capacitor C11, an emitter electrode of the triode Q5 is connected with ground, the collector electrode of the triode Q5 is respectively connected with the other end of the resistor R9, the other end of the capacitor C11 and one end of a capacitor C12, the other end of the capacitor C12 is respectively connected with the base electrode of the triode Q4, one end of a grounding inductor L8 and one end of a capacitor C13, the other end of the capacitor C13 is respectively connected with one end of a grounding inductor L9 and one end of a capacitor C14, and the other end of the capacitor C14 is connected with a grid electrode of a field effect transistor Q2;

the large frequency offset correction circuit comprises a triode Q6, wherein the base electrode of the triode Q6 is connected with the other end of the inductor L5, the collector electrode of the triode Q6 is respectively connected with the negative electrode of the electrolytic capacitor E5 and one end of the resistor R10, the other end of the resistor R10 is connected with a power supply +5V, the positive electrode of the electrolytic capacitor E5 is respectively connected with the positive electrode of the diode D2 and the emitting electrode of the triode Q7, the base electrode of the triode Q7, the negative electrode of the diode D2 and the emitting electrode of the triode Q6 are connected with the ground, and the collector electrode of the triode Q7 is connected with the negative electrode of the varactor BD 1.