Anti-interference narrow-bandwidth low-frequency receiver

Abstract

The utility model relates to an anti-interference narrow-bandwidth low-frequency receiver applied to the field of receivers, which comprises a receiving antenna, an output end of the receiving antenna is electrically connected with a fifty-hertz wave trap, the other end of the fifty-hertz wave trap is electrically connected with a band-pass filter BP 1, the other end of the band-pass filter BP 1 is electrically connected with a secondary frequency-selecting amplifier, and the secondary frequency-selecting amplifier is electrically connected with a frequency-selecting antenna. The other end of the second-stage frequency-selecting amplifier is electrically connected with a band-pass filter BP 2, the other end of the band-pass filter BP 2 is electrically connected with a third-stage amplifier, the other end of the third-stage amplifier is electrically connected with a voltage follower, and the other end of the voltage follower is electrically connected with a rectifier diode. The receiver performs high-multiple amplification on effective signals and attenuates noise interference signals, the tracking efficiency of the receiver on the pipe cleaner is improved, the interference signal false alarm rate of the receiver is effectively reduced, the searching time of the pipe cleaner is shortened, and the searching efficiency is improved.

Description

Technical Field

[0001] The utility model relates to a low-frequency receiver, in particular to an anti-interference narrow-bandwidth low-frequency receiver applied to the field of receivers. Background Art

[0002] The long-distance pipeline needs to be regularly cleaned of internal impurities. When using a pigging device for pigging, a transmitter and a receiver are required to cooperate for positioning and tracking. Since the pipeline is made of carbon steel, it shields medium and high-frequency wireless signals. Therefore, the transmitter generally emits low-frequency electromagnetic signals. The low-frequency electromagnetic signals can penetrate the metal pipe wall and the buried soil layer to transmit the signals to the probe antenna of the receiver, and the receiver processes and amplifies the signals for display.

[0003] Generally, the frequency bandwidth of the low-frequency receivers commonly used in the market for long-distance pipelines is about 2 Hz. The wide frequency bandwidth makes it easy to generate low-frequency signals close to the received frequency in a noisy environment, which will cause false alarms of noise signals in the receiver and make it impossible to accurately judge whether the signal is emitted by the low-frequency transmitter. Content of the Utility Model

[0004] Aiming at the above-mentioned prior art, the technical problem to be solved by the utility model is that generally, the frequency bandwidth of the existing low-frequency receivers is about 2 Hz. The wide frequency bandwidth makes it easy to generate low-frequency signals close to the received frequency in a noisy environment, which will cause false alarms of noise signals in the receiver and make it impossible to accurately judge whether the signal is emitted by the low-frequency transmitter.

[0005] To solve the above problems, the utility model provides an anti-interference narrow-bandwidth low-frequency receiver, which includes a receiving antenna. The output end of the receiving antenna is electrically connected to a 50 Hz notch filter. The other end of the 50 Hz notch filter is electrically connected to a band-pass filter BP1. The other end of the band-pass filter BP1 is electrically connected to a second-stage frequency-selective amplifier. The other end of the second-stage frequency-selective amplifier is electrically connected to a band-pass filter BP2. The other end of the band-pass filter BP2 is electrically connected to a third-stage amplifier. The other end of the third-stage amplifier is electrically connected to a voltage follower. The other end of the voltage follower is electrically connected to a rectifier diode. The other end of the rectifier diode is respectively electrically connected to a microammeter and an IC6 inverter. The other end of the IC6 inverter is electrically connected to a light-emitting diode and a pulse generator. The other end of the pulse generator is electrically connected to a speaker.

[0006] In the above anti-interference narrow-bandwidth low-frequency receiver, the receiver amplifies the effective signal by a high multiple, attenuates the noise interference signal, improves the tracking efficiency of the receiver for the pigging device, effectively reduces the false alarm rate of the interference signal of the receiver, thereby reducing the search time for the pigging device and improving the search efficiency.

[0007] As a further improvement of the present application, the receiving antenna includes L1 and C1 connected in parallel. The 50 Hz notch filter includes a dual-channel low-noise amplifier chip IC1. The receiving antenna is electrically connected to pin 3 of the dual-channel low-noise amplifier chip IC1 through C2. The other end of C2 is electrically connected to R3, and the other end of R3 is electrically connected to R1, R2, and C3.

[0008] As a supplement to the further improvement of the present application, the dual-channel low-noise amplifier chip IC1 forms a negative feedback circuit limiting amplifier through R5 and R4, and the amplification factor of the negative feedback circuit limiting amplifier is four times. Pin 1 of the dual-channel low-noise amplifier chip IC1 is electrically connected to a 50 Hz power frequency notch filter. The 50 Hz power frequency notch filter includes RT1, RT2, C6, and C4, C5, RT3.

[0009] As a supplement to the further improvement of the present application, one end of the dual-channel low-noise amplifier chip IC1 is electrically connected to a twin-T notch filter and C8. The twin-T notch filter includes R6 and R7, and C8 is electrically connected to a band-pass filter BP1.

[0010] As a further improvement of the present application, the band-pass filter BP1 includes IC2 and a band-pass filter. The band-pass filter 1 includes a high-frequency twin-T filter 1 and a low-frequency twin-T filter 1. The high-frequency twin-T filter includes C9, C10, C11, and R10, R11. The low-frequency twin-T filter includes R12, R13, R14, and C12, C13. There is an R15 electrically connected between the band-pass filter BP1 and the second-stage frequency selection amplifier.

[0011] As a further improvement of the present application, the second-stage frequency selection amplifier includes IC3 and a twin-T notch negative feedback circuit electrically connected to IC3. The twin-T notch negative feedback circuit includes C17, C18, RT5, RT6, R16, and C19. There are C20 and RT7 electrically connected between the second-stage frequency selection amplifier and the band-pass filter BP2.

[0012] As another improvement of the present application, the band-pass filter BP2 includes IC4 and a band-pass filter 2. The band-pass filter 2 includes a high-frequency twin-T filter 2 and a low-frequency twin-T filter 2. The high-frequency twin-T filter 2 includes C21, C22, C23, and R17, R18. The low-frequency twin-T filter 2 includes R21, R22, R23, and C24, C25.

[0013] As another improvement of the present application, the three-stage amplifier includes IC5 and a negative feedback circuit electrically connected to IC5. The negative feedback circuit includes R24 and R25. IC5 is electrically connected to a voltage follower through R26.

[0014] As another improvement of the present application, the voltage follower is electrically connected to the rectifying diode through C29, and the rectifying diode is electrically connected to the microammeter through C30, R28 and D3. The R34 and C37 of the pulse generator form a fixed oscillation frequency, and the fixed oscillation frequency controls the speaker through C38 coupling.

[0015] In summary, in the actual application process, after the receiving antenna receives the low-frequency signal transmitted by the low-frequency transmitter, the receiving antenna transmits the signal to the 50 Hz notch filter, filters it by C3, amplifies it by the negative feedback circuit amplifier, filters out the 50 Hz power frequency by the 50 Hz power frequency notch filter, then filters it once through the band-pass filter BP1, amplifies the signal through the second-stage frequency-selective amplifier, filters it twice through the band-pass filter BP2, locks the amplification factor at 60 times by the negative feedback circuit of the three-stage amplifier, rectifies the signal amplified by power through the voltage follower by the rectifying diode, the microammeter displays the signal amplitude through the swing of the ammeter pointer, the light-emitting diode emits a light signal for indication, the signal triggers the pulse generator to work. After being triggered, the oscillation frequency output is coupled through C38 to control the speaker to emit a sound prompt at a fixed frequency, so as to amplify the effective signal by a high multiple, attenuate the noise interference signal, improve the tracking efficiency of the receiver for the pig, effectively reduce the false alarm rate of the interference signal of the receiver, thereby reducing the searching time of the pig and improving the searching efficiency. Brief Description of the Drawings

[0016] Figure 1 is the circuit block diagram of the present application;

[0017] Figure 2 is the application schematic diagram of the 50 Hz notch filter of the present application;

[0018] Figure 3 is the application schematic diagram of the band-pass filter BP1 of the present application;

[0019] Figure 4 is the application schematic diagram of the second-stage frequency-selective amplifier of the present application;

[0020] Figure 5 is the application schematic diagram of the band-pass filter BP2 of the present application;

[0021] Figure 6 is the application schematic diagram of the three-stage amplifier of the present application;

[0022] Figure 7 is the application schematic diagram of the voltage follower of the present application;

[0023] Figure 8 is the application schematic diagram of the pulse generator of the present application.

[0024] Description of the reference numerals in the drawings:

[0025] 1 Receiving antenna, 2 50 Hz notch filter, 3 Band-pass filter BP1, 4 Second-stage frequency-selective amplifier, 5 Band-pass filter BP2, 6 Third-stage amplifier, 7 Voltage follower, 8 Rectifier diode, 9 Microammeter, 10 IC6 inverter, 11 Light-emitting diode, 12 Pulse generator, 13 Speaker. Detailed implementation

[0026] The following will describe the implementation of the present application in detail with reference to the accompanying drawings.

[0027] Figure 1 Shown: An anti-interference narrow-bandwidth low-frequency receiver, including a receiving antenna 1, the output end of the receiving antenna 1 is electrically connected to a 50 Hz notch filter 2, the other end of the 50 Hz notch filter 2 is electrically connected to a band-pass filter BP1 3, the other end of the band-pass filter BP1 3 is electrically connected to a second-stage frequency-selective amplifier 4, the other end of the second-stage frequency-selective amplifier 4 is electrically connected to a band-pass filter BP2 5, the other end of the band-pass filter BP2 5 is electrically connected to a third-stage amplifier 6, the other end of the third-stage amplifier 6 is electrically connected to a voltage follower 7, the other end of the voltage follower 7 is electrically connected to a rectifier diode 8, the other end of the rectifier diode 8 is respectively electrically connected to a microammeter 9 and an IC6 inverter 10, the other end of the IC6 inverter 10 is electrically connected to a light-emitting diode 11 and a pulse generator 12, the light-emitting diode 11 can emit a light signal for indication, after the signal is limited and amplified by the IC6 inverter 10, one path is given to the base of the switching triode T5, and the switching triode follows the signal change to control the light-emitting diode 11 to give a light signal indication, the other end of the pulse generator 12 is electrically connected to a speaker 13, and the speaker 13 can emit a sound signal for reminder.

[0028] Figure 2 Shown: The receiving antenna 1 includes L1 and C1 connected in parallel, the 50 Hz notch filter 2 includes a dual-channel low-noise amplification chip IC1, the receiving antenna 1 is electrically connected to the 3rd pin of the dual-channel low-noise amplification chip IC1 through C2, the other end of C2 is electrically connected to R3, the other end of R3 is electrically connected to R1, R2 and C3, the dual-channel low-noise amplification chip IC1 forms a negative feedback circuit through R5 and R4 to limit the amplifier, and the amplification factor of the negative feedback circuit limiting the amplifier is four times, the 1st pin of the dual-channel low-noise amplification chip IC1 is electrically connected to a 50 Hz power frequency notch filter, the 50 Hz power frequency notch filter includes RT1, RT2, C6 and C4, C5, RT3, one end of the dual-channel low-noise amplification chip IC1 is electrically connected to a twin-T notch filter and C8, the twin-T notch filter includes R6 and R7, C8 is electrically connected to the band-pass filter BP1 3, the parallel R6 and R7 of the twin-T notch filter are voltage-divided to adjust the Q value of the twin-T notch filter to 1.7 to ensure that the notch filter works within the optimal notch efficiency range, the 8th pin of IC1 is connected to the power supply and filtered by C7, and the 4th pin of IC1 is grounded.

[0029] Figure 3 It shows that the band-pass filter BP-3 includes IC2 and a band-pass filter. The band-pass filter 1 includes a high-frequency twin-T filter 1 and a low-frequency twin-T filter 1. The high-frequency twin-T filter includes C9, C10, C11 and R10, R11. The low-frequency twin-T filter includes R12, R13, R14 and C12, C13. There is an electrical connection of R15 between the band-pass filter BP-3 and the second-stage frequency-selective amplifier 4.

[0030] Figure 4 It shows that the second-stage frequency-selective amplifier 4 includes IC3 and a twin-T notch negative feedback circuit electrically connected to IC3. The twin-T notch negative feedback circuit includes C17, C18, RT5, RT6, R16 and C19. There are electrical connections of C20 and RT7 between the second-stage frequency-selective amplifier 4 and the band-pass filter BP-2 5. After being current-limited by R15, the signal enters the 5-pin amplifier input terminal of IC3 and is amplified 200 times by the amplifier. The negative feedback notch filter only amplifies the signal frequency center, and all other noise frequency signals outside the range of plus or minus 1% of the signal center frequency are attenuated. The signal filtered by this narrow-bandwidth filter is coupled through C20.

[0031] Figure 5 It shows that the band-pass filter BP-2 5 includes IC4 and a band-pass filter 2. The band-pass filter 2 includes a high-frequency twin-T filter 2 and a low-frequency twin-T filter 2. The high-frequency twin-T filter 2 includes C21, C22, C23 and R17, R18. The low-frequency twin-T filter 2 includes R21, R22, R23 and C24, C25. After being filtered by the band-pass filter 2, it enters the 3-pin amplifier input terminal of IC5 in the third-stage amplifier 6. The amplification factor is locked at 60 times through the negative feedback circuit composed of R24 and R25.

[0032] Figure 6 It shows that the third-stage amplifier 6 includes IC5 and a negative feedback circuit electrically connected to IC5. The negative feedback circuit includes R24 and R25. IC5 is electrically connected to the voltage follower 7 through R26. The amplified signal is output from the 1-pin of IC5. After being current-limited by the current-limiting resistor R26, it is given to the base of the power amplification triode of the voltage follower 7. The signal power-amplified by the voltage follower 7 is coupled through the C29 capacitor and then given to the rectifier diode 8 for rectification.

[0033] Figure 6 and Figure 8It is shown that: there is an electrical connection between the voltage follower 7 and the rectifying diode 8 through C29, and there is an electrical connection between the rectifying diode 8 and the microammeter 9 through C30, R28 and D3. The microammeter 9 displays the signal amplitude through the swing of the ammeter pointer. The R34 and C37 of the pulse generator 12 form a fixed oscillation frequency. The fixed oscillation frequency controls the speaker 13 through C38 coupling. The R34 and C37 of the pulse generator 12 form a fixed oscillation frequency. The signal triggers the pulse generator to work. After being triggered, the oscillation frequency is output from pin 3 of IC7 in the pulse generator 12 and controls the speaker to emit a sound prompt at a fixed frequency after being coupled through C38.

[0034] During use, after the receiving antenna 1 receives the low-frequency signal transmitted by the low-frequency transmitter, the receiving antenna 1 transmits the signal to the 50 Hz notch filter 2, filters it through C3, amplifies it by the negative feedback circuit amplifier, filters out the 50 Hz power frequency by the 50 Hz power frequency notch filter, performs a primary filter through the band-pass filter BP-3, amplifies the signal by the second-stage frequency selection amplifier 4, performs a secondary filter through the band-pass filter BP-2 5, locks the amplification factor at 60 times by the negative feedback circuit of the three-stage amplifier 6, and the signal after power amplification by the voltage follower 7 is rectified by the rectifying diode 8. The microammeter 9 displays the signal amplitude through the swing of the ammeter pointer, and the light-emitting diode 11 emits a light signal for indication. The signal triggers the pulse generator 12 to work. After being triggered, the oscillation frequency output is coupled through C38 to control the speaker 13 to emit a sound prompt at a fixed frequency, so as to amplify the effective signal by a high multiple, attenuate the noise interference signal, improve the tracking efficiency of the receiver for the pigging device, effectively reduce the false alarm rate of the interference signal of the receiver, thereby reducing the pigging device search time and improving the search efficiency.

[0035] Combined with the current actual requirements, the above implementation manner adopted in this application, the protection scope is not limited thereto. Within the knowledge scope of those skilled in the art, various changes made without departing from the concept of this application still fall within the protection scope of this utility model.

Claims

1. An anti-interference narrow bandwidth low frequency receiver, comprising a receiving antenna (1), characterized in that: The output end of the receiving antenna (1) is electrically connected to a fifty-hertz notch filter (2), the other end of the fifty-hertz notch filter (2) is electrically connected to a bandpass filter BP-1 (3), the other end of the bandpass filter BP-1 (3) is electrically connected to a secondary frequency selective amplifier (4), the other end of the secondary frequency selective amplifier (4) is electrically connected to a bandpass filter BP-2 (5), the other end of the bandpass filter BP-2 (5) is electrically connected to a third-stage amplifier (6), the other end of the third-stage amplifier (6) is electrically connected to a voltage follower (7), the other end of the voltage follower (7) is electrically connected to a rectifier diode (8), the other end of the rectifier diode (8) is electrically connected to a microampere ammeter (9) and an IC6 inverter (10), respectively, the other end of the IC6 inverter (10) is electrically connected to a light-emitting diode (11) and a pulse generator (12), and the other end of the pulse generator (12) is electrically connected to a speaker (13).

2. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The receiving antenna (1) comprises L1 and C1 connected in parallel, the 50 Hz notch filter (2) comprises a dual-channel low-noise amplifier chip IC1, the receiving antenna (1) is electrically connected to pin 3 of the dual-channel low-noise amplifier chip IC1 via C2, the other end of C2 is electrically connected to R3, and the other end of R3 is electrically connected to R1, R2 and C3.

3. The anti-interference narrow bandwidth low frequency receiver according to claim 2, characterized in that: The dual-channel low-noise amplifier chip IC1 forms a negative feedback circuit limiting amplifier through R5 and R4, and the negative feedback circuit limits the amplifier's amplification factor to four times. Pin 1 of the dual-channel low-noise amplifier chip IC1 is electrically connected to a 50 Hz power frequency trap, and the 50 Hz power frequency trap includes RT1, RT2, C6 and C4, C5, RT3.

4. The anti-interference narrow bandwidth low frequency receiver according to claim 2, characterized in that: One end of the dual-path low-noise amplifier chip IC1 is electrically connected to a dual-T trap and C8, wherein the dual-T trap includes R6 and R7, and C8 is electrically connected to a band-pass filter BP-(3).

5. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The bandpass filter BP-1 (3) comprises IC2 and a bandpass filter, the bandpass filter 1 comprises a high-frequency twin-T filter 1 and a low-frequency twin-T filter 1, the high-frequency twin-T filter comprises C9, C10, C11 and R10, R11, the low-frequency twin-T filter comprises R12, R13, R14 and C12, C13, and R15 is electrically connected between the bandpass filter BP-1 (3) and the secondary frequency selective amplifier (4).

6. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The secondary frequency selective amplifier (4) comprises IC3 and a double T notch negative feedback circuit electrically connected to IC3, the double T notch negative feedback circuit comprises C17, C18, RT5, RT6, R16 and C19, and C20 and RT7 are electrically connected between the secondary frequency selective amplifier (4) and the band pass filter BP2 (5).

7. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The bandpass filter BP2 (5) includes IC4 and bandpass filter 2, the bandpass filter 2 includes high-frequency twin-T filter 2 and low-frequency twin-T filter 2, the high-frequency twin-T filter 2 includes C21, C22, C23 and R17, R18, and the low-frequency twin-T filter 2 includes R21, R22, R23 and C24, C25.

8. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The three-stage amplifier (6) comprises an IC5 and a negative feedback circuit electrically connected to the IC5, the negative feedback circuit comprises R24 and R25, and the IC5 is electrically connected to the voltage follower (7) via R26.

9. The anti-interference narrow bandwidth low frequency receiver according to claim 1, characterized in that: The voltage follower (7) is electrically connected to the rectifier diode (8) via C29, the rectifier diode (8) is electrically connected to the microampere ammeter (9) via C30, R28 and D3, R34 and C37 of the pulse generator (12) form a fixed oscillation frequency, and the fixed oscillation frequency is coupled to control the speaker (13) via C38.

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