RU2263887C1 - Method and device for detecting leakage in pressure pipeline - Google Patents

Abstract

FIELD: measuring engineering.

SUBSTANCE: device comprises connected in series transmitter whose control input is connected with the first output of the synchronizer and transmitting aerial, first receiving aerial, first receiver, first switch whose second input is connected with the second output of the synchronizer through a time delay unit, first multiplier, first narrow-band filter, amplitude limiter, phase detector whose second input is connected with the first output of the heterodyne, output voltmeter, comparator, second switch whose second input is connected with the output of the voltmeter, indicator, second receiving aerial, second receiver, heterodyne, first mixer, and first amplifier of intermediate frequency. The transmitting aerial has linear polarization. The first receiving aerial is sensitive to the signals with the right circular polarization, and second receiving aerial is sensitive to the signals with left circular polarization. The device is also provided with the second and third narrow-band filters, phase inverter, two adders, two 90° phase shifter, second mixer, second amplifier of the intermediate frequency, second multiplier, amplitude detector, and third switch. The output of the second receiver is in communication with the connected in series second narrow-band filter, phase inverter, first adder whose second input is connected with the output of the second receiver, second mixer whose second input is connected with the first output of heterodyne through the first 90° phase sifter, second amplifier of intermediate frequency, second 90° phase shifter, second adder whose second input is connected with the output of the first amplifier of intermediate frequency, second multiplier whose second input is connected with the output of the first adder, third narrow-band filter, amplitude detector, and third switch whose input is connected with the output of the second adder and output is connected with the second input of the first multiplier. The output of the first adder is connected with the second input of the first mixer.

EFFECT: enhanced precision and resistance to noise.

2 cl, 2 dwg

Description

The proposed method and device relate to the control and measuring technique and can be used to determine the coordinates of the leak in the underground pipelines of heat and water supply systems.

Known methods and devices for determining the location of a leak in underground pipelines (ed. Certificate of the USSR No. 336463, 380909, 380910, 411268, 417675, 724957, 930909, 934269, 941776, 947666, 1079946, 1208402, 1216550, 1283566, 1368685, 1610347, 1657988, 1672105, 1679232, 1777014, 1781577, 1800219, 1812386; RF patents No. 20111110, 2036372, 2047039, 2047815, 2053436, 2084757, 2204119; US patents No. 3045116, 3744298, 4289019, 4570477; UK patent; France patent no. 2374628, 2504651; German patent No. 3112829; Japanese patents No. 46-4795, 55-6856, 59-38.537, 63-22531; Voloshin V.I. et al. Acoustic locator of a developing defect. // Defectoscopy, 1980, No. 8 , p.69-74 and others).

Of the known methods closest to the proposed one is the "Method of determining the place of a leak in the pressure pipe and a device for its implementation" (RF patent No. 2204119, G 01 M 3/08, 2001), which are selected as prototypes.

However, in the known method and device for its implementation, the same value of the intermediate frequency ω _pr can be obtained by receiving signals at two frequencies ω _s and ω _s , i.e.

ω _ol = ω _s -ω _g , and ω _ol = ω _g -ω _s .

Therefore, if the tuning frequency ω _to take over the main receiving channel, along with it will be present mirror reception channel, the frequency ω _of which differs from the frequency (ω _a main channel 2ω _straight and are arranged symmetrically (mirror) relative to frequency ω _r LO (Figure 2). conversion of the image channel reception takes place with the same conversion coefficient K, _etc., as the main channel, so it is the most significant effect on immunity, selectivity and accuracy of determining the location of a leak in the pressure ruboprovode.

In addition to the mirror, there are other additional (combination) reception channels, the frequency of which can be determined as follows:

ω _ave = | ± mω _ki ± nω _g |,

where ω _ki is the frequency of the i-th Raman reception channel;

m, n, i are positive integers.

The most harmful combinational reception channels are those generated by the interaction of the signal frequency with the harmonics of the frequency of the local oscillator of the small order (second, third, etc.), since the sensitivity of the receiving device through these channels is close to the sensitivity of the main receiving channel. So, two combination channels with m = 1 and n = 2 correspond to frequencies:

ω _k1 = 2ω _g -ω _pr and ω _k2 = 2ω _g + ω _pr

If the interference frequency is equal to the intermediate frequency, then a direct channel is formed.

The presence of false signals (interference) received through the mirror and Raman channels, as well as through the direct channel, leads to a decrease in noise immunity, selectivity and accuracy of determining the place of a leak in the pressure pipe.

An object of the invention is to increase the noise immunity, selectivity and accuracy of determining the location of a leak in a pressure pipe by suppressing false signals (interference) received via additional channels.

The problem is solved in that according to the method for determining the location of a leak in a pressure pipe under a layer of soil, based on electromagnetic sounding of the soil along the pipeline route by a plane polarized electromagnetic wave and receiving signals with right and left circular polarization reflected from the pipeline, the signal with the right they are gated with circular polarization in time, proportional to the depth of the pipeline, and the signal with left circular polarization is converted in frequency, emit intermediate frequency and then isolate the harmonic voltage at a stable local oscillator frequency, limit it in amplitude, measure the phase shift between the signals with right and left circular polarization at a stable local oscillator frequency, compare the measured phase shift with a reference value and decide on if there is a leak in the monitored pipeline, in the signal receiving channel with left circular polarization, a false signal (interference) is emitted at the intermediate frequency, invert it by Then they are summed up with the initial received false signal (interference), the local oscillator phase voltage is shifted 90 ° and used for additional conversion of the received signal frequency, an additional intermediate frequency voltage is isolated, 90 ° phase shifted, the main and additional intermediate voltage are summed frequency, multiply the resulting total voltage of the intermediate frequency with the received signal, isolate the voltage at the local oscillator frequency, detect it and use it as a control system Nala to enable multiplying the obtained total voltage of the intermediate frequency signal with the right circular polarization.

This object is achieved in that the device for determining the location of a leak in the pressure pipe, containing a series-connected transmitter, the control input of which is connected to the first output of the synchronizer, and a transmitting antenna, series-connected the first receiving antenna, the first receiver, the first key, the second input of which through the unit time delay is connected to the second output of the synchronizer, the first multiplier, the first narrow-band filter, an amplitude limiter, a phase detector, the second input of which is dinene with the first output of the local oscillator, an output voltage meter, a comparison unit, a second key, the second input of which is connected to the output of the output voltage meter, and an indicator, a second receiving antenna and a second receiver in series, a local oscillator, a first mixer and a first intermediate frequency amplifier, while the transmitting antenna is linearly polarized, the first receiving antenna is susceptible to signals with right circular polarization, the second receiving antenna is susceptible to signals with circular polarization, equipped with a second and third narrow-band filters, a phase inverter, two adders, two 90 ° phase shifters, a second mixer, a second intermediate frequency amplifier, a second multiplier, an amplitude detector and a third key, and a second narrow-band filter is connected in series to the output of the second receiver, a phase inverter, a first adder, the second input of which is connected to the output of the second receiver, a second mixer, the second input of which is connected through the first phase shifter 90 ° to the first output a local oscillator house, a second intermediate frequency amplifier, a second 90 ° phase shifter, a second adder, the second input of which is connected to the output of the first intermediate frequency amplifier, a second multiplier, the second input of which is connected to the output of the first adder, a third narrow-band filter, an amplitude detector and a third key, the second input of which is connected to the output of the second adder, and the output is connected to the second input of the first multiplier, the output of the first adder is connected to the second input of the first mixer.

The structural diagram of a device that implements the proposed method is presented in figure 1. A frequency diagram explaining the principle of formation of additional reception channels is shown in FIG.

The device comprises serially connected synchronizer 13, transmitter 1 and transmitting antenna 3, serially connected first receiving antenna 4, first receiver 2, first key 15, the second input of which is connected through the time delay unit 14 to the second output of synchronizer 13, the first multiplier 21, the first narrowband a filter 22, an amplitude limiter 23, a phase detector 5, the second input of which is connected to the first output of the local oscillator 18, an output voltage meter 6, a comparison unit 24, a second switch 25, the second input of which is connected with the output of the output voltage meter 6, and an indicator 26, sequentially connected to the second receiving antenna 16, the second receiver 17, the second narrow-band filter 27. The phase inverter 28, the first adder 29, the second input of which is connected to the output of the second receiver 17, the first mixer 19, the second input which is connected to the second output of the local oscillator 18, and the first intermediate frequency amplifier 20, connected in series to the output of the first adder 29, a second mixer 31, the second input of which is connected through the first phase shifter 30 by 90 ° to the first output the local oscillator 18, the second intermediate frequency amplifier 32, the second phase shifter 33 by 90 °, the second adder 34, the second input of which is connected to the output of the first intermediate frequency amplifier 20, the second multiplier 35, the second input of which is connected to the output of the first adder 29, the third narrow-band filter 36 , an amplitude detector 37 and a third key 38, the second input of which is connected to the output of the second adder 34, and the output is connected to the second input of the first multiplier 21.

The suppression of false signals (interference) received through the direct channel at an intermediate frequency ω _pr is provided by a “filter plug” consisting of a narrow-band filter 27, a phase inverter 28, and a first adder 29 and implementing a phase compensation method.

The suppression of false signals (interference) received through the mirror channel at a frequency ω _s and through the first combination channel at a frequency ω _k1 is provided by the "outer ring" consisting of mixers 19 and 31, a local oscillator 18, phase shifters 30 and 33 by 90 °, amplifiers 20 and 32 of the intermediate frequency, the second adder 34 and implements phase-compensation method.

Suppression of false signals (interference) received via the second combinational channel at a frequency ω _{k2 is} provided by the "inner ring" consisting of a multiplier 35, a narrow-band filter 38 and implementing the narrow-band filtering method.

The proposed method is as follows. The synchronizer 13 generates stable rectangular video pulses with a known repetition period T _SL and duration T _and that periodically trigger the transmitter 1. The latter generates a high-frequency probe signal with linear polarization

u _s (t) = U _s cos (ω _s t + φ _s ), 0≤t≤T _and ,

where U _s , ω _s , φ _s , T _and are the amplitude, carrier frequency, initial phase and duration of the probe signal, which is transmitted through the transmitting antenna 3 in the direction of the pipeline 8, which is under the soil layer 7. An electromagnetic field is created in the soil 7 by electromagnetic sounding along the pipeline route. When the probing signal 9 reaches the pipeline 8, it is partially reflected towards the surface of the earth (point A). The reflected signal 10 is captured by the receiving antennas 4 and 19. In this case, the receiving antenna 4 is susceptible only to the signal with the right circular polarization, and the receiving antenna 19 is only susceptible to the signal with the left circular polarization.

The output of the receivers 2 and 17 produces the following signals:

u _p (t) = U _s (t) cos [(ω _s ± Δω) t + φ ₁ ],

u _l (t) = U _l (t) cos [(ω _with ± Δω) t + φ ₂ ],

where the indices "p" and "l" refer respectively to signals with right and left circular polarization;

U _p (t), U _l (t) - envelopes of signals with right and left circular polarization;

± Δω - carrier frequency instability caused by incoherent reflection and other destabilizing factors.

The signal U _p (t) from the output of the receiver 2 through the key 15 is fed to the first input of the multiplier 21. In order for the measured phase difference to correspond to the depth h of the pipe 8, the multiplier 21 is time-gated using the key 15, to the control input of which short rectangular video pulses with output block 14 time delay. The time delay of the pulses is determined by the depth h of the pipeline 8 in the soil 7. When the depth changes, the delay time also changes.

The signal U _l (t) from the output of the receiver 17 through the first adder 29 is supplied to the first inputs of the mixers 19 and 31, the second inputs of which are supplied with the local oscillator voltage 18, respectively:

u _g1 (t) = U _g cos (ω _g t + φ _g ),

u _g2 (t) = U _g cos (ω _g t + φ _g + 90 °),

where U _g , ω _g , φ _g - amplitude, frequency and initial phase of the local oscillator voltage.

Since the tuning frequency ω _{n1 of the} narrow-band filter 27 is chosen equal to the intermediate frequency ω _pr (ω _n1 = ω _pr ), then the adder 29 only has one arm.

At the outputs of the mixers 19 and 31, voltages of combination frequencies are generated. Amplifiers 20 and 32 are allocated only the voltage of the intermediate (differential) frequency:

_pr1 u (t) = U _pr (t) cos [(ω _ave ± Δω) t + φ _etc.],

_np2 u (t) = U _pr (t) cos [(ω _ave ± Δω) t ± φ _pr -90 °], 0≤t≤T _and

;Where

;

To ₁ - gear ratio of the mixers;

ω _CR = ω _with -ω _g is the intermediate frequency;

φ _ol = φ ₂ -φ _g .

The voltage U _CR2 (t) from the output of the intermediate frequency amplifier 32 is supplied to the input of the phase shifter 33 by 90 °, at the output of which a voltage is generated

u _pr3 (t) = U _pr (t) cos [(ω _pr ± Δω) t + φ _pr -90 ° + 90 °] = U _pr (t) cos [(ω _pr ± Δω) t + φ _pr

Voltages u _CR1 (t) and u _CR3 (t) are supplied to two inputs of the adder 34, the output of which is formed by the total voltage

u _∑ (t) = U _∑ (t) cos [(ω _ol ± Δω) t + φ _ol ],

where U _∑ (t) = 2U _pr (t).

This voltage is supplied to the first input of the multiplier 35, the second input of which receives the received signal u _l (t). The output of the multiplier 35 is formed voltage

u ₁ (t) = U ₁ (t) cos (ω _g t + φ _g ), 0≤t≤T _and ,

;Where

;

K ₂ is the transmission coefficient of the multiplier.

Since the tuning frequency ω _{n2 of the} narrow-band filter 36 is chosen equal to the frequency ω _{g of the} local oscillator 18 (ω _n2 = ω _g ), the voltage u ₁ (t) is emitted by the narrow-band filter 36, is detected by the amplitude detector 37 and is supplied to the control input of the key 38, opening it . In the initial state, key 38 is always closed. The voltage u _∑ (t) from the output of the adder 34 through the public key 38 is supplied to the second input of the multiplier 21. At the output of the latter, a harmonic voltage is generated

u ₂ (t) = U ₂ (t) cos (ω _g t + φ _g + Δφ), 0≤t≤T _and ,

;Where

;

Δφ = φ ₂ -φ ₁ is the phase difference between the signals with the right and left circular polarization,

which is allocated by a narrow-band filter 22 and fed to the input of the amplitude limiter 23. At the output of the latter, a voltage is generated

u ₃ (t) = U _ogr cos (ω _g t + φ _g + Δφ), 0≤t≤T _and ,

where U _ogre is the limit threshold,

which is fed to the first input of the phase detector 5, the second input of which is supplied with the voltage u _g (t) of the local oscillator 18. A constant voltage is generated at the output of the latter

u _n (Δφ) = U _n cosΔφ,

;Where

;

K ₃ - the transfer coefficient of the phase detector,

proportional to the measured phase shift Δφ. This voltage is measured by a meter 6 of the output voltage. In block 24 comparison compares the measured value of the output voltage with a reference value

u _e (Δφ _E ) = U _E cosΔφ _e ,

where Δφ _e - unchanged phase shift obtained by probing the soil over undamaged sections of the pipeline 8.

The phase shift Δφ is determined by the frequency of the probing signal and the electrical parameters of the soil 7. This phase shift remains unchanged when probing the soil over undamaged sections of the pipeline 8, since all its determining quantities remain constant. Therefore, in block 24 comparison stores the reference value of the output voltage corresponding to the phase shift when probing the soil over undamaged sections of the pipeline.

When u _n (t) ≈u _e (t) in block 24 of the comparison of the constant voltage is not formed.

When probing the soil over the damaged section 11 of the pipeline 8 (point B), the signals with right and left circular polarization partially pass through the wet layer 12 of the soil 7 formed when the fluid flows out of the controlled pipeline 8.

When an electromagnetic wave propagates through wet soil having electrical parameters different from dry soil (high conductivity and permittivity), the phase velocity of the wave propagates.

When a plane-polarized electromagnetic wave is reflected from the pipeline, which is affected by the external magnetic field of the Earth, it is divided into two independent components, which in the general case have elliptical polarization with opposite directions of rotation. At frequencies of the decimeter range, both components have circular polarization. Both components of the electromagnetic wave propagate in the wet layer 12 of the soil 7 with different speeds, as a result of which the phase relations between these waves change.

This phenomenon is usually called the Faraday effect, due to which the reflected signal experiences the rotation of the plane of polarization. The angle of rotation of the plane of polarization, which is determined by the different speed of propagation of signals with right and left circular polarization along the wet soil layer, is found from the ratio:

where φ ₁ , φ ₂ are the phase delays of signals with right and left circular polarization, respectively.

All this leads to a change in the phase shift Δφ and the value of the output voltage u _n (Δφ) of the phase detector 5. When u _n (Δφ)> u _e (Δφ), a constant voltage is generated in the comparison unit 24, which is supplied to the control input of the key 25, opening his. In the initial state, keys 15, 25, and 38 are always closed. In this case, the output voltage u _n (Δφ) from the output of the output voltage meter 6 is supplied through a public key 25 to the input of the indicator 26. Moreover, the fact of registration of the output voltage u _n (Δφ) of phase measurement indicates a leak in this section of the pipeline 8, and the value This voltage characterizes the degree of damage to the pipeline.

The application of the proposed method facilitates the finding of an underground pipeline route from the earth’s surface, since when deviating to the side of the pipeline route it will be detected by the absence of a reflected signal 10.

It should be noted that in the proposed method, reflections from the air-ground surface are eliminated, polarization selection is used, and the ambiguity of phase measurements is eliminated, which is achieved by the fact that phase measurements are carried out between signals with right and left circular polarization, and not between sounding and reflected signals. In this case, the phase shift (Δφ) between the reflected signals with right and left circular polarization is measured at a stable frequency ω _{g of the} local oscillator 18. Therefore, the process of measuring the phase shift is invariant to the instability of the amplitude and carrier frequency of the reflected signal arising from incoherent reflection of the signal from the pipeline and due to other destabilizing factors, which allows to increase the accuracy of measuring the phase shift Δφ and, therefore, the accuracy of determining the place of a leak in a pressure pipe located under a layer of cargo ta.

The above operation of a device that implements the proposed method corresponds to the case of receiving a signal reflected from the pipeline with left circular polarization along the main channel at a frequency ω _s (Fig. 2).

If a false signal (interference) is received through the direct channel at a frequency ω _CR

_WP4 u (t) = U _WP4 cos (ω _ave t + φ _WP4) 0≤t≤T _pr

then it is allocated by a narrow-band filter 27 and enters the input of the phase inverter 28, where it is inverted in phase by 180 °

_np5 u (t) = - U _WP4 cos (ω _ave t + φ _WP4).

The _voltages u _CR4 (t) and u _CR5 (t) supplied to the two inputs of the adder 29 are compensated at its output.

Therefore, a false signal (interference) received on the direct channel at a frequency ω _CR is suppressed.

If a false signal (interference) is received on the mirror channel at a frequency of ω _s

_s u (t) = U _s cos (ω _ave t + φ _pr6), 0≤t≤T _s,

the amplifiers 20 and 32 of the intermediate frequency are allocated the following voltages:

_pr6 u (t) = U _pr6 cos (ω _ave t + φ _pr6)

_pr7 u (t) = U _pr6 cos (ω _ave t + φ _pr6 + 90 °), 0≤t≤T _s,

;Where

;

_straight ω = ω _r -ω _s - intermediate frequency; φ _pr6 = φ _g -φ _s .

The voltage u _pr7 (t) from the output of the intermediate frequency amplifier 32 is supplied to the input of the phase shifter 33 by 90 °, at the output of which a voltage is generated

u _pr8 (t) = U _pr6 cos (ω _pr t + φ _pr6 + 90 ° + 90 °) =

= -U _pr6 cos (ω _ave t + φ _pr6), 0≤t≤T _h.

The voltage u _CR6 (t) and u _CR8 (t) supplied to the two inputs of the adder 34, at its output are compensated.

Therefore, a false signal (interference) received on the mirror channel at a frequency ω _s is suppressed.

For a similar reason, a false signal (interference) received on the first combination channel at a frequency ω _{k1 is also} suppressed.

If a false signal (interference) is received on the second combination channel at a frequency ω _k2

u _k2 (t) = U _k2 cos (ω _k2 t + φ _k2 ), 0≤t≤T _k2 ,

the amplifiers 20 and 32 of the intermediate frequency are allocated the following voltages:

u _pr9 (t) = U _pr9 cos (ω _pr t + φ _pr9 ), 0≤t≤T _k2 ,

u _pr10 (t) = U _pr9 cos (ω _pr t + φ _pr9 -90 °)

;Where

;

ω = ω _{ave k2} -2ω _g - intermediate frequency; φ _pr9 = φ _k2 -φ _g .

The voltage u _pr10 (t) from the output of the intermediate frequency amplifier 32 is supplied to the input of the phase shifter 33 by 90 °, at the output of which a voltage is generated

u _pr11 (t) = U _pr9 cos (ω _pr t + φ _pr9 -90 ° + 90 °) =

= U _pr9 cos (ω _ave t + φ _pr9), 0≤t≤T _k2.

Voltages u _pr9 (t) and u _pr11 (t) are supplied to two inputs of the adder 34, at the output of which the total voltage is formed

_{u Σ1 (t) = U Σ1} cos (ω _ave t + φ _pr9) 0≤t≤T _k2,

.Where

.

This voltage is supplied to the first input of the multiplier 35, the second input of which receives the received signal u _r2 (t). The output of the multiplier 35 produces the following voltage:

u ₄ (t) = U ₄ cos (2ω _g t + φ _g ), 0≤t≤T _k2 ,

,Where

,

which does not fall into the passband of the narrow-band filter 36. The key 38 does not open, and the false signal (interference) received on the second combination channel at a frequency ω _k2 is suppressed.

Thus, the proposed method and device in comparison with prototypes and other technical solutions of a similar purpose provides increased noise immunity, selectivity and accuracy of determining the place of a leak in a pressure pipe located under a layer of soil. This is achieved by suppressing false signals (interference) received through the direct channel, through the mirror and Raman channels. In this case, to suppress false signals (interference) received through the direct channel through the mirror and the first combination channels, the phase-compensation method is used. And to suppress false signals (interference) received on the second combinational channel, the method of narrow-band filtering is used.

Claims (2)

1. A method for determining the location of a leak in a pressure pipe under a layer of soil, based on electromagnetic sounding of the soil along the pipeline route by a plane polarized electromagnetic wave and receiving signals with right and left circular polarization, while the signal with right circular polarization is gated in time proportional to the depth pipeline, and the signal with left circular polarization is converted in frequency, the intermediate frequency voltage is isolated, and then the harmonic voltage n stable frequency of the local oscillator, limit it in amplitude, measure the phase shift between signals with right and left circular polarization at a stable frequency of the local oscillator, compare the measured value of the phase shift with the reference value and, based on the results of the comparison, decide on the presence of a leak in the controlled pipeline, characterized in that a signal from the left circularly polarized light is passed through a narrow band filter whose tuning frequency is selected equal to the intermediate frequency ω ₌ ω _{H1 Ave,} shifted in phase by 180 ° and summarize with a signal with left circular polarization, the total signal is additionally converted in frequency using the local oscillator voltage 90 ° out of phase, an additional intermediate frequency voltage is isolated, it is shifted 90 ° in phase, summed with the intermediate frequency voltage, the resulting total voltage is multiplied with the total signal, the voltage at the local oscillator frequency is isolated, it is detected and used as a control signal to allow multiplication of the obtained total voltage between internal frequency signal with the right circular polarization. 2. A device for determining the place of a leak in the pressure pipe, containing a series-connected transmitter, the control input of which is connected to the first output of the synchronizer, and a transmitting antenna, series-connected first reception antenna, a first receiver, a first key, the second input of which is connected to the second output of the synchronizer, the first multiplier, the first narrow-band filter, an amplitude limiter, a phase detector, the second input of which is connected to the first output of the local oscillator, an output voltage amplifier, a comparison unit, a second key, the second input of which is connected to the output of the output voltage meter, and an indicator, a second receiving antenna and a second receiver connected in series, a local oscillator, a first mixer and a first intermediate frequency amplifier, while the transmitting antenna has a linear polarization, the first receiving antenna is susceptible to signals with a right circular polarization, the second receiving antenna is susceptible to signals with a left circular polarization, different the fact that it is equipped with a second and third narrow-band filters, a phase inverter, two adders, two 90 ° phase shifters, a second mixer, a second intermediate frequency amplifier, a second multiplier, an amplitude detector and a third key, and a second narrow-band filter is connected in series to the output of the second receiver, phase inverter, first adder, the second input of which is connected to the output of the second receiver, the second mixer, the second input of which is connected through the first phase shifter 90 ° to the first output of the local oscillator a, a second intermediate frequency amplifier, a second phase shifter 90 °, a second adder, the second input of which is connected to the output of the first intermediate frequency amplifier, a second multiplier, the second input of which is connected to the output of the first adder, a third narrow-band filter, an amplitude detector and a third switch, the second the input of which is connected to the output of the second adder, and the output is connected to the second input of the first multiplier, the output of the first adder is connected to the second input of the first mixer.

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