CN111476137A - Novel pipeline leakage early warning online correlation positioning data compression method and equipment - Google Patents
Novel pipeline leakage early warning online correlation positioning data compression method and equipment Download PDFInfo
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Abstract
The invention discloses a novel pipeline leakage early warning online correlation positioning data compression method and equipment, wherein the method comprises the following steps: collecting a noise sample; carrying out FFT (fast Fourier transform) operation on the collected noise samples to obtain noise frequency domain information; recombining frequency spectrum in a frequency domain by a frequency band migration method, reserving an effective pipeline noise frequency band, and discarding out-of-band noise; performing an IFFT (inverse Fourier transform) transformation operation to obtain a time domain signal after frequency domain compression; and finally, carrying out ADPCM compression coding and outputting a compressed code stream. The invention has the advantages of good selectivity, good anti-interference performance, high compression rate, no phase distortion, simple algorithm and the like.
Description
Technical Field
The invention relates to the field of signal and information processing, in particular to a novel pipeline leakage early warning online related positioning data compression method and equipment.
Background
When a pipe leaks, the fluid medium passes through the leak gap at high speed, and due to vibration, friction, deceleration, expansion, impact, etc., the fluid generates reynolds stress or shear force, creating leak noise. The leakage sound waves propagate in the pipeline and pipeline fluid in the forms of non-dispersive plane waves and dispersive higher-order sound modes, are influenced by attenuation characteristics of the fluid and the pipeline, and the noise intensity is rapidly weakened along with the increase of the propagation distance. By utilizing the characteristic of noise generated when a pipeline leaks, various pipe network leakage detection/monitoring devices (such as leakage monitoring instruments, correlation instruments, leakage early warning and the like) are developed at home and abroad, and a noise detection method is also a current main use method of a water supply pipe network.
The common leakage early warning equipment is important equipment applying a noise detection method, adopts a noise intensity characteristic discrimination method, generally selects to collect noise data in a period of 2: 00-4: 00 at night, and mainly aims to reduce environmental noise interference and reduce false alarm and false alarm probability. During collection, noise data are collected according to a fixed interval T seconds (generally 5-10 seconds, different manufacturers are slightly different), noise intensity is calculated, and the total collection times are N times (generally N times)>1000 times), for the convenience of analysis, the discrete sequence of noise intensities acquired N times is defined as f (t), and an intensity range threshold V is defined at the same timeth(generally set at about 5db, slightly different from manufacturer) and the excision value Vcut(generally about 20db, different manufacturers are slightly different), and the leakage determination method comprises the following steps:
1. when MIN (F (t)>＝VcutAnd MAX (F (t)) -MIN (F (t)))<＝VthSometimes, leakage occurs;
2. when MIN (F (t)<VcutOr MAX (F (t)) -MIN (F (t)))>VthNo leakage occurs;
where MAX () takes the maximum value of the sequence and MIN () takes the minimum value of the sequence. The method mainly judges whether leakage occurs or not according to the characteristics that the leakage noise intensity is relatively stable and the environmental noise randomness is strong.
Although the common leakage early warning equipment can early warn pipeline faults, the leakage points cannot be accurately positioned on line, and when leakage occurs, engineers need to use professional instruments (leak listening instruments, related instruments and the like) to position the leakage points on site. In order to solve the problem, the development of leakage early warning supporting an online positioning function is carried out on schedule, and online positioning version leakage early warning realizes online automatic leakage point positioning while realizing leakage early warning. The equipment collects pipeline noise data of not less than 3 seconds at night, the data are compressed and then transmitted to a central server through the Internet of things, and the server completes cross-correlation operation of adjacent monitoring points and automatically positions the positions of leaking points.
The leakage early warning equipment is arranged underground for a long time and is powered by a battery, and the leakage early warning equipment belongs to micro-power consumption and micro-bandwidth application equipment. Practice proves that the data transmission power consumption accounts for more than 70% of the total power consumption of the equipment, and if the total data volume of 3-second samples collected by the data transmission power consumption is 10KHz 3 s 2B (byte) 60KB with the 16-bit collection width and the 10KHz sampling frequency, the data transmission power consumption is reduced by compressing the data. Although current audio compression techniques are mature and have many types of compression, there are still many deficiencies for pipeline leak-point related positioning applications. The pipeline leakage noise and the leakage point positioning have unique characteristics, and are specifically represented in the following aspects:
1. the frequency bands are different: the sound transmission characteristics of different pipes are different, and the audio transmission characteristics of common pipes are shown in fig. 3 (pipe noise transmission band table): the leakage noise frequency band of the ductile cast iron pipeline is distributed in the range of 200 Hz-800 Hz, the leakage noise of the polyvinyl chloride pipeline is distributed in the range of 100 Hz-600 Hz, the leakage noise of the cement pipeline is distributed in the range of 200 Hz-1200 Hz, and the leakage noise of the galvanized steel pipeline is distributed in the range of 400 Hz-1200 Hz. The compression is carried out according to the specific frequency band characteristics of different pipes, so that the compression ratio is favorably improved, the data volume is reduced, and the out-of-band noise interference is favorably inhibited.
2. Low frequency band and high sampling rate: it can be known from fig. 3 (pipeline noise propagation band table) that different pipeline noise bands are distributed between 100Hz to 1200Hz, and according to the sampling theorem, the sampling rate is not lower than 2400Hz, and according to the requirement of the industry, the positioning accuracy error is not greater than 1 meter, and the correlation resolution is not greater than 0.1ms (millisecond), so the minimum sampling rate of 10KHz (resolution: 1000ms/10K is 0.1ms) is generally adopted. The higher sampling rate increases the data volume, is not beneficial to micro-power consumption and micro-bandwidth application, so the sound transmission characteristics of different pipes are required to be combined for compression, only the effective noise bandwidth is reserved, and the invalid out-of-band noise is discarded. Taking the polyvinyl chloride pipeline as an example, if the sampling rate is 10KHz, the frequency band range after fourier transform is 0-5 KHz, as shown in fig. 4 (effective spectrum range of the polyvinyl chloride pipeline). The pipeline leakage noise is distributed between 100Hz and 600Hz, the occupied proportion of effective leakage noise in the whole frequency spectrum is very small, and the effective leakage noise is lower than 100Hz and higher than 600Hz, and belongs to environmental noise.
3. Phase sensitivity: different from the conventional voice compression algorithm, the cross-correlation operation is sensitive to the phase according to the cross-correlation theory, so that the compression algorithm is required to be lossless to the phase. The cross-correlation function is as follows:
4. the leakage early warning equipment is powered by a battery and arranged underground for a long time, and requires micro power consumption work and extremely small transmission bandwidth, and practical application shows that: when the equipment is in standby operation, the electricity consumption is only a few microamps, the average electricity consumption is more than 250 milliamperes during transmission, the instantaneous current consumption reaches 800 milliamperes or even higher, and the electricity consumption of transmission loss accounts for more than 70% of the total electricity consumption, so that the compression ratio is provided as far as possible, the data volume is reduced, and the purposes of reducing the electricity consumption of transmission and prolonging the service life are achieved.
5. The algorithm is simple: because the terminal equipment adopts a low-speed MCU in order to reduce power consumption and has limited operation capability, the complexity of a compression algorithm is reduced as much as possible.
Disclosure of Invention
The invention aims to provide a novel pipeline leakage early warning online correlation positioning data compression method and equipment, which aim at the online leakage point positioning application requirement according to the pipeline noise propagation characteristics and solve the problem of a data compression technology suitable for the online leakage point positioning of a pipe network.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method of pipeline noise compression, the method comprising: collecting noise data of the pipeline, and performing analog-to-digital conversion; acquiring noise data, and performing FFT (fast Fourier transform) operation to obtain noise frequency domain information; recombining frequency spectrum in a frequency domain according to the sound transmission characteristics of the pipeline by a frequency band migration method, only reserving an effective pipeline noise frequency band, and discarding out-of-band interference noise; then, the time domain signal is restored through IFFT (inverse fast Fourier transform); and finally, outputting a compressed code stream through ADPCM coding in a time domain.
To achieve the above object, there is also provided a data compression apparatus including: the acquisition unit is used for acquiring pipeline noise data and performing analog-to-digital conversion; an FFT operation unit: carrying out FFT (fast Fourier transform) operation on the collected pipeline noise data to obtain pipeline noise frequency domain information; the frequency band migration unit recombines the frequency spectrum in a frequency domain according to the sound transmission characteristics of the pipeline by a frequency band migration method, only reserves an effective pipeline noise frequency band, and discards out-of-band interference noise; an IFFT operation unit which performs IFFT (inverse fast Fourier transform) conversion operation on the frequency spectrum data after the frequency band migration to obtain a time domain signal after frequency domain compression; ADPCM coding unit: and performing compression coding on the output signal of the IFFT operation unit by using an ADPCM algorithm, and outputting a compressed code stream.
In order to achieve the above object, there is also provided a method for decompressing pipeline noise, the method comprising: receiving the compressed code stream; carrying out ADPCM decoding on the compressed code stream; then obtaining frequency domain information through FFT (fast Fourier transform) conversion operation; performing reverse migration on the frequency spectrum in a frequency domain by a frequency band recovery method, and recovering the original position of the effective pipeline noise frequency band; and finally, performing IFFT (inverse fast Fourier transform) operation to reduce the time domain signals into decompressed time domain signals.
To achieve the above object, there is also provided a pipeline noise decompression apparatus, including: a receiving unit for receiving the compressed code stream; an ADPCM decoding unit for decoding the compressed code stream by using an ADPCM algorithm; an FFT operation unit: performing FFT (fast Fourier transform) operation on the ADPCM decoded data to obtain frequency domain information; a band recovering unit: reversely transferring the frequency spectrum in the frequency domain, and recovering the original position of the effective frequency band of the pipeline noise; an IFFT operation unit: and expanding the frequency spectrum and restoring the decompressed pipeline noise time domain signal.
The invention has the advantages and positive effects that:
compared with the prior art, the invention adopts the frequency domain and time domain dual compression technology, comprehensively considers the noise propagation characteristics of the pipeline and the requirements of practical application scenes, is suitable for pipelines made of different materials, has the characteristics of high compression ratio, good anti-interference performance, simple algorithm and the like, and meets the requirements of phase sensitive application, and is explained in detail below.
1. The invention has the advantages of flexible selectivity and out-of-band interference resistance
The transmission of the pipeline leakage noise is influenced by the attenuation characteristic of the pipeline material, different pipes show different frequency band characteristics (see figure 3), and the algorithm can selectively reserve the pipeline leakage noise frequency band according to the on-site pipes and shield out-of-band noise interference. For example, the nodular cast iron pipeline only selects and reserves frequency band information in the range of 200 Hz-800 Hz; the polyvinyl chloride pipeline only selects and reserves frequency band information within the range of 100Hz to 600 Hz; the cement pipeline only selects and reserves frequency band information within the range of 200 Hz-1200 Hz; the galvanized steel pipeline only selects and reserves frequency band information in the range of 400Hz to 1200 Hz. In practical pipe applications, leakage noise comes from inside the pipe, while environmental noise comes primarily from outside the pipe. Practice proves that environmental noise is a main factor influencing related positioning accuracy, the problem is well solved by adopting selective compression, the data volume is reduced, and out-of-band noise interference is inhibited.
2. The invention has the advantage of high compression ratio
Taking the pvc pipe as an example, if the sampling rate is 10KHz and the sampling bit is 16 bits wide, the original data amount of 1 second is 10KHz by 1 second by 2B (byte) 20 KB. As can be seen from FIG. 3, the noise frequency band of the polyvinyl chloride pipeline is distributed in the range of 100 Hz-600 Hz, and the bandwidth is 500 Hz. The method comprises the steps that original collected data are subjected to FFT (fast Fourier transform) conversion to obtain a frequency spectrum in a range of 0-5 KHz, and the compression ratio of the original data and an effective pipeline noise frequency band is 5KHz/500Hz and 10: 1. If ADPCM adopts a commonly used 16:4 compression ratio, the total compression ratio is 40:1, and the compressed data is only 512B (bytes). The higher sampling rate ensures the accuracy of related positioning, and the high compression ratio reduces the data transmission quantity, reduces the equipment power consumption, prolongs the equipment service life and saves precious bandwidth resources.
3. The invention satisfies the phase sensitive application
In the application of accurate positioning of a pipeline leakage point, the currently commonly used equipment for accurately positioning the leakage point of the pipeline network mainly comprises a correlator, a multi-probe correlator and the like, which are all based on cross-correlation operation, and the cross-correlation operation is sensitive to phase, and the change of the phase directly influences an operation result, so that the problems of large error of positioning the leakage point, incapability of positioning and the like are caused. The algorithm is based on frequency domain and time domain dual compression, and the compression process is completed through frequency domain migration in a frequency domain, so that the phase of effective leakage noise is guaranteed to be lossless, and the interference of out-of-band noise is also inhibited. ADPCM compression and decompression are adopted in a time domain, ADPCM coding utilizes the correlation of adjacent audio data in time, the audio data of adjacent sampling points have similar characteristics, and the difference correlation well describes the phase characteristics of signals.
Drawings
FIG. 1 is a schematic flow chart of the encoding algorithm of the present invention;
FIG. 2 is a schematic flow chart of the decoding algorithm of the present invention;
FIG. 3 is a table of frequency bands of common pipe noise propagation characteristics;
FIG. 4 shows the effective spectrum range of a polyvinyl chloride pipe;
FIG. 5 is a diagram of a noise spectrum of a polyvinyl chloride pipe;
FIG. 6 is a schematic diagram of the band shifting of the present invention;
FIG. 7 is a band migration flow diagram of the present invention;
FIG. 8 is a band recovery flow diagram of the present invention;
fig. 9 is an ADPCM coding frame diagram.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
To summarize:
the leakage noise is formed by a fluid medium passing through a leakage gap at a high speed to generate reynolds stress or shearing force, and is influenced by the attenuation characteristics of the aqueous fluid and the pipeline, the high-frequency attenuation speed of the leakage noise is much higher than the low-frequency attenuation speed in the propagation process, and the attenuation characteristics of the pipelines made of different materials to sound are also different, which is specifically shown in fig. 3. The frequency band characteristics of all commonly used pipelines are comprehensively considered, the frequency of leakage noise is mainly distributed in the range of 100-1.2 KHz, and the sampling frequency is not lower than 2.4KHz according to Shannon sampling theorem. And a positioning error of no more than 1 meter and a correlation resolution of no more than 0.1ms (milliseconds) are required according to the industry, so a minimum sampling rate of 10KHz is generally adopted. The higher sampling rate increases the data volume, is not favorable to leakage early warning, and is arranged in the underground throughout the year, and the micro-power consumption and micro-bandwidth application equipment powered by the battery are provided.
From the view of the pipeline noise composition, the pipeline noise comprises two parts of pipeline leakage noise and environmental noise, the leakage noise comes from the inside of the pipeline, the environmental noise comes from the outside of the pipeline, the environmental noise belongs to Gaussian white noise, and the spectral power distribution conforms to Gaussian distribution. Practice proves that environmental noise is a main factor influencing the related positioning accuracy, so in the pipeline leakage positioning application, the influence of the environmental noise must be maximally shielded.
The algorithm comprehensively considers the sound transmission characteristics of pipelines made of different materials and the characteristics of practical application scenes, has the characteristics of selective compression according to the frequency band characteristics of different pipes, good anti-interference performance, high sampling rate, low phase distortion, high compression ratio, simple algorithm and the like, and meets the application requirements of pipeline leakage positioning. The algorithm compression and encoding process flow is shown in fig. 1, and the decompression process flow is shown in fig. 2.
And (3) an encoding process: collecting a pipeline noise sample, and performing analog-to-digital conversion; acquiring noise data, and performing FFT (fast Fourier transform) operation to obtain noise frequency domain information; recombining frequency spectrum in a frequency domain according to the sound transmission characteristics of the pipeline by a frequency band migration method, only reserving an effective pipeline leakage noise frequency band, and discarding out-of-band interference noise; then, the time domain signal is restored through IFFT (inverse fast Fourier transform); and finally, outputting a compressed code stream through ADPCM coding in a time domain.
And (3) decoding process: receiving the compressed code stream; carrying out ADPCM decoding on the compressed code stream; then obtaining frequency domain information through FFT (fast Fourier transform) operation; performing reverse migration on the frequency spectrum in a frequency domain by using a frequency band recovery method, and recovering the original position of the effective pipeline leakage noise frequency band; and finally, restoring the time domain signals into decompressed time domain signals through IFFT (inverse fast Fourier transform) operation.
For a better illustration of the invention, the following sections are described in detail:
band selective compression principle:
the leakage noise frequency band distribution of different pipes is different due to the influence of the attenuation characteristic of the pipeline material, and the out-of-band noise is a main factor influencing the related accuracy and must be filtered by a technical means. Therefore, when compressing, according to the current pipeline material, the effective pipeline leakage noise frequency band is selectively reserved in the frequency domain, and the ineffective out-of-band noise is discarded. As shown in fig. 3: the nodular cast iron pipeline reserves frequency band information in the range of 200 Hz-800 Hz; the polyvinyl chloride pipeline reserves frequency band information in the range of 100 Hz-600 Hz; reserving frequency band information in the range of 200 Hz-1200 Hz for the cement pipeline; the galvanized steel pipeline reserves frequency band information in the range of 400 Hz-1200 Hz. The data after selective compression only contains effective leakage noise information, so that the compression ratio is improved, the data volume is reduced, and meanwhile, the data has better filtering performance and is beneficial to improving the related accuracy. In order to realize the band selective compression, the algorithm completes the band selective compression process and the band selective recovery process through the band migration process and the band recovery process, which will be described in detail below.
Band migration principle:
the frequency band migration is a specific implementation process of selective compression of the frequency band, the frequency domain is recombined according to the noise frequency band characteristics of different pipes, effective leakage noise frequency bands are selectively reserved, and out-of-band interference noise is discarded. And (3) band migration process: the lower limit frequency point of the current pipe noise is set as flowThe upper limit frequency point is ftopThen the leakage noise band of the current pipe can be recorded as Flog(flow，ftop). If the current sampling frequency fs (the sampling value is greater than or equal to 10KHz), the frequency band after FFT (fast Fourier transform) operation can be recorded as Ffft(0, fs/2). As can be seen from fig. 3 and 4, the leakage noise band Flog(flow，ftop) Much smaller than the original frequency band Ffft(0, fs/2), adding Flog(flow，ftop) The range spectrum data is migrated to the original band 0 start position and discarded (f)top-flow) All the above spectral data form a new frequency band Fnew(0,ftop-flow). For F againnew(0, ftop-flow) And performing IFFT (inverse fast Fourier transform) operation by using the minimum number of points to obtain a time domain signal only containing pipeline leakage noise.
For convenience of explaining the frequency band migration principle, the polyvinyl chloride pipe is taken as an example, and as can be seen from fig. 3, the lower limit frequency f of the leakage noise of the polyvinyl chloride pipelow100Hz, upper limit frequency point ftop600Hz, frequency band denoted Flog(100Hz, 600 Hz). The sampling frequency fs is 10KHz, the upper limit frequency fs/2 is 5KHz, and the frequency band is denoted as Ffft(0Hz,5 KHz). The leakage noise spectrum of a polyvinyl chloride pipe is shown in fig. 5, where the abscissa represents frequency in Hz and the ordinate represents amplitude in db. F is to belogThe frequency spectrum data in the range of (100Hz, 600Hz) is transferred to the initial position of the frequency spectrum 0, and the interference noise data content above 600Hz is discarded to form a new frequency band Fnew(0,500Hz), the band shifting process is shown in fig. 6 and 7.Finally, F is aligned againnewPerforming an IFFT (inverse fast fourier transform) operation with the minimum number of points results in a time-domain signal containing only pipe leakage noise. If the number of FFT operations before band migration is 10240, the minimum number of IFFT operations is 1024.
Band recovery principle:
the frequency band recovery is the inverse process of frequency band migration, and the frequency domain restoration of effective pipeline leakage noise is completed, and the original frequency spectrum is reconstructed. And (3) band recovery process: let the FFT point number be P in the spectrum migration processfftLet the IFFT point number be P in the spectrum migration processifft. First of all with PifftThe point number executes FFT conversion to obtain frequency band data F after frequency band migrationnew(0,ftop-flow). Then with PfftPoint number spread spectrum, spread part filled with 0, and Fnew(0,ftop-flow) Migration of spectral data to Flog(flow，ftop) And (4) corresponding to the position. Finally, with PfftAnd performing IFFT operation on the point number to obtain a restored pipeline leakage noise time domain signal. The band recovery process is illustrated in fig. 8.
Or polyvinyl chloride pipeline with sampling rate fs of 10KHz and Pfft＝10240，Pifft1024. Firstly, executing FFT operation on the time domain signal after frequency band migration by 1024 points to obtain frequency domain data F after frequency band migrationnew(0,500 Hz). Spread spectrum to 10240 point, fill the spread portion with 0, and then Fnew(0,500Hz) spectral data migration to Flog(100Hz, 600Hz) corresponds to position. So far, the original position of the pipeline leakage noise is restored in the frequency domain, and a new frequency spectrum F is obtainedfft(0Hz,5 KHz). And finally, performing IFFT operation at 10240 points to obtain a restored pipeline leakage noise time domain signal.
ADPCM coding and decoding principle:
an Adaptive Differential Pulse Code Modulation (ADPCM), the g.726 audio coding algorithm is also an ADPCM algorithm, and the coding diagram is shown in fig. 9. The ADPCM coding is a predictive coding algorithm, which uses the time correlation of adjacent audio data and adopts a quantizer with variable step size to perform predictive coding. The coding process of ADPCM can be divided into three steps: firstly, calculating the error between the current actual value and the predicted value; secondly, carrying out quantization coding on the error; and the third step is updating the predictor. The ADPCM decoding is the inverse of the ADPCM coding, and the decoding process can also be divided into three steps: firstly, obtaining a predicted value; the second step executes the decoding process; and thirdly, updating the predicted value.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the respective technical features described in the above embodiments may be combined in any suitable manner without contradiction.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (2)
1. A novel pipeline leakage early warning online correlation positioning data compression method is characterized by comprising two steps of pipeline noise compression and decompression:
pipeline noise compression: collecting a pipeline noise sample, and performing analog-to-digital conversion; obtaining noise frequency domain information through FFT transformation operation; recombining frequency spectrum in a frequency domain by a frequency band migration method, reserving effective pipeline leakage noise frequency domain information, and discarding out-of-band interference noise; then, the time domain signals are restored through IFFT conversion operation; finally, outputting a compressed code stream through ADPCM compression coding;
pipeline noise decompression: carrying out ADPCM decoding on the received compressed code stream; then obtaining frequency domain information through FFT transformation operation; performing reverse migration on the frequency spectrum in a frequency domain by using a frequency band recovery method, and recovering the original position of the effective pipeline leakage noise frequency band; and finally, restoring the time domain signals into decompressed time domain signals through IFFT operation.
2. The utility model provides a novel online relevant location data compression equipment of pipeline seepage early warning, its characterized in that, this equipment includes pipeline noise compression and pipeline noise decompression two parts:
the pipeline noise compression comprises an acquisition unit for acquiring a pipeline noise sample and completing analog-to-digital conversion; the FFT operation unit is used for carrying out FFT conversion operation on the pipeline noise sample after the analog-digital conversion to obtain noise frequency domain information; the frequency band migration unit is used for reserving effective pipeline leakage noise frequency domain information and discarding out-of-band interference noise according to the sound transmission characteristics of pipelines made of different materials; an IFFT operation unit which performs IFFT conversion operation on the frequency domain data after the frequency band migration to obtain a time domain signal after frequency domain compression; the ADPCM coding unit is used for carrying out compression coding on the compressed time domain signal by applying an ADPCM algorithm and outputting a compressed code stream;
the pipeline noise decompression comprises a receiving unit for receiving the compressed code stream; an ADPCM decoding unit for decoding the compressed code stream by applying an ADPCM algorithm; the FFT operation unit is used for carrying out FFT operation on the data decoded by the ADPCM to obtain frequency domain information; the frequency band recovery unit is used for reversely transferring the frequency band in the frequency domain and recovering the original position of the effective pipeline leakage noise frequency band; and the IFFT operation unit is used for restoring the decompressed pipeline noise time domain signal.
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