CN106789804A - The 4000000 high speed well logging communication technologys - Google Patents

The 4000000 high speed well logging communication technologys Download PDF

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Publication number
CN106789804A
CN106789804A CN201610810510.4A CN201610810510A CN106789804A CN 106789804 A CN106789804 A CN 106789804A CN 201610810510 A CN201610810510 A CN 201610810510A CN 106789804 A CN106789804 A CN 106789804A
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CN
China
Prior art keywords
data
technology
logging
ofdm
high speed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201610810510.4A
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Chinese (zh)
Inventor
腾明晖
张仕龙
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BEIJING GEO-VISTA TECHNOLOGY Ltd
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BEIJING GEO-VISTA TECHNOLOGY Ltd
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Priority to CN201610810510.4A priority Critical patent/CN106789804A/en
Publication of CN106789804A publication Critical patent/CN106789804A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2666—Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2676—Blind, i.e. without using known symbols
    • H04L27/2678—Blind, i.e. without using known symbols using cyclostationarities, e.g. cyclic prefix or postfix
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation

Abstract

The present invention relates to a kind of Highspeed Data Transmission Technology based on wireline logging, its highest transmission bit rates are 4 Mbit/s.The technology is a kind of technology that high speed data transfer is realized for well logging industry application modern communication technology, to adapt to the increasing data demand of industry of logging well.In modulator approach, using orthogonal frequency division multiplexi OFDM, it is transformed to some sub- circuit-switched data streams to this technology by by serial data stream, and corresponding subcarrier is modulated with the diffluence of low speed subdata, forms multiple low speed symbol parallels and sends.Because by the data symbol persistence length relative increase on each subcarrier after serioparallel exchange, along with Cyclic Prefix, so as to eliminate the influence of intersymbol interference well.Mutually orthogonal between each subcarrier in other ofdm system, sub-channel spectra is overlapped, and frequency spectrum resource is using very high.In sum, OFDM technology is combined with INVENTIONModern cable logging signal transmission technology, substantially increases the data transmission bauds of logging cable.Meet the increasing requirement of INVENTIONModern cable logging technique data volume.

Description

The 4000000 high speed well logging communication technologys
Technical field
The 4000000 high speed well logging communication technology of the present invention is High-Speed Communication Technique in petrol exploration cable well logging field Application, using OFDM technology, realize the high speed well logging communication that maximum transmission rate is 4Mbit/s.
Background technology
It is low-pass characteristic that the amplitude versus frequency characte of logging cable is cashed, and the amplitude-frequency of logging cable is tested by using Network Analyzer Characteristic finds that frequency is more than 100KHz signals, by after 7600 meters of logging cables long, nearly 80 points of signal fading badly Shellfish, cannot modulate.If simply transmitting log data using simple base band transmission, it is impossible to meet modern logger The increasing requirement of data volume.
OFDM technology is modulated data on the mutually orthogonal subcarrier of frequency, and the frequency band of each subcarrier about exists 4KHz, the information for so making is propagated in the environment of relative low pass, decay and the phase delay of signal amplitude is reduced, so that very Good overcomes the narrow defect of the frequency band of logging cable.Band efficiency is improve, Cyclic Prefix is increased, and eliminate well The influence of intersymbol interference.
The content of the invention
The present invention relates to a kind of Highspeed Data Transmission Technology based on petroleum cable well logging, its highest transmission bit rates are 4Mbit/s.The technology is a kind of technology that high speed data transfer is realized for oil well logging industry application modern communication technology, with Adapt to the increasing data transportation requirements of well logging industry.
The technology uses orthogonal frequency division multiplex OFDM technology, and it is transformed to some sub- circuit-switched datas by by serial data stream Stream, corresponding subcarrier is modulated with these low speed subdata diffluences, is formed multiple low speed symbol parallels and is sent.Because by string simultaneously Data symbol persistence length relative increase after conversion on each subcarrier, along with Cyclic Prefix, so as to eliminate well The influence of intersymbol interference.Mutually orthogonal between each subcarrier in other ofdm system, sub-channel spectra is overlapped, frequency spectrum resource Using very high.
1st, the 4000000 high speed well logging communication technology, it is characterised in that geological data is modulated by OFDM in downhole instrument string Plate, after pseudorandomcode 1, before encoding 2, block interleaving 3, constellation mapping 4, Inverse Fast Fourier Transforms 5, then process circulation using RS Sew 6 insertion algorithms, being converted into analog signal by D/A converter 7 is sent to logging cable.Information is uploaded to by logging cable Ground solution tuned plate is demodulated.Data are by the way that after discretization 8, by synchronized algorithm 9, fast Fourier algorithm 10, CP is removed 11st, user data upload to ground is become after channel equalization 12, demapping 13, deinterleaving 14, RS decoding 15, solution pseudorandomcode 16 Plane system software.
2nd, the 4000000 high speed well logging communication technology according to claim 1, it is characterised in that selected frequency band range It is 12k~512k, is divided into 128 sub-channels.
3rd, the 4000000 high speed well logging communication technology according to claim 1, it is characterised in that the symbol time for being used It is 256*1us, protection interval 0us.
4th, the 4000000 high speed well logging communication technology according to claim 1, it is characterised in that Cyclic Prefix uses 32 Individual, pilot tone is 2 the 9th and the 122nd subchannels, and EFC is encoded to RS codings, and it is block interleaving to interweave.
5th, the 4000000 high speed well logging communication technology according to claim 1, it is characterised in that super frame has 128 OFDM symbol, including a training sequence.
6th, the 4000000 high speed well logging communication technology according to claim 1, it is characterised in that each sub-channels Bit numbers are 8bit, with a width of 500kHz, so peak transfer rate is exactly 8bit*500kHz=4Mbit/s.
7th, simultaneous techniques：Because OFDM is a kind of multi-carrier modulation technology, with respect to being required more for single carrier modulation technique Strict synchronization.The synchronization of ofdm system includes three aspects：(1) carrier synchronization (2) sample synchronization (3) timing synchronization.
Carrier synchronization 17：Realized by two processes, i.e. acquisition mode and tracking pattern.The first stage appoints in receiver Business seeks to carry out coarse frequency estimation as soon as possible, solves the Trapped problems of carrier wave；The task of second stage can exactly be locked And perform tracing task.
Sample synchronization 18：Sample synchronization is realized by pilot signal.
Timing synchronization 19：Increase Cyclic Prefix.
Beneficial effects of the present invention：
1. the 4000000 high speed well logging communication technologys improve the data transmission capabilities of logging cable.Meet modern logger The requirement of big data quantity transmission.
Brief description of the drawings
The design frame chart of Fig. 1 OFDM technologies.
Synchronous several aspects in Fig. 2 ofdm systems.
4,000,000 high speed well logging communication scheme in Fig. 3 ofdm systems.
Specific embodiment
1.FEC code Designs
As shown in figure 1, being encoded using RS, RS (114,98), a synchronizing sequence (training sequence), every 128 OFDM symbols Number composition one superframe, use a training sequence.
2. interleaving design
As shown in figure 1, RS codings can use convolutional interleave or block interleaving, block interleaving is selected in this invention.
3. constellation mapping design
Using 128 sub-channels, planisphere is mapped from Gray's agate.
4. receiving terminal Synchronization Design
It is synchronous to occupy very important status in a communications system.For example, when using synchronous demodulation or coherent detection, connecing Receipts machine needs to extract one with transmitting carrier wave with frequently with the carrier wave of phase；Original position of symbol etc. is also predefined simultaneously, such as Fig. 2 institutes Show.
There is following stationary problem in general communication system：
The carrier frequency of transmitter and receiver is different；
The sample frequency of transmitter and receiver is different；
Receiver does not know the timing original position of symbol.
OFDM symbol is made up of the superposition of multiple sub-carrier signals, is distinguished using orthogonality between each subcarrier, therefore Ensure this orthogonality for ofdm system it is critical that, therefore its requirement to carrier synchronization is also just relatively tight Lattice.
There is synchronous requirement following aspects in an ofdm system：
Carrier synchronization 17：The frequency of oscillation of receiving terminal will with send carrier wave with the same phase of frequency, as shown in Figure 2.
Sample synchronization 18：Receiving terminal is consistent with the sampling frequency of transmitting terminal, as shown in Figure 2.
Timing synchronization 19：Inverse fourier transform (IFFT) is consistent with Fourier transform (FFT) start/stop time, such as Fig. 2 It is shown.
Compared with single-carrier system, requirement of the ofdm system to synchronization accuracy is higher, and synchronism deviation can be in an ofdm system Cause inter-carrier interference (ICI) and intersymbol interference (ISI).Required bottom panel show the synchronization in ofdm system, and probably Provide various synchronizations location in systems.
Carrier synchronization:
Frequency departure between emitter and receiver causes reception signal to be shifted in frequency domain.If frequency departure The n (n is integer) times of subcarrier spacing, although be maintained between subcarrier it is orthogonal, but frequency adopted value is The n position of subcarrier is offset by, causes the bit error rate of the data symbol being mapped in OFDM frequency spectrums to be up to 0.5.
If carrier frequency offset is not the integral multiple of subcarrier spacing, will there is energy between subcarriers " leakage ", causes the orthogonality between subcarrier to be destroyed, so as to introduce interference between subcarriers so that the error code of system Rate penalty.
Generally we realize carrier synchronization, i.e. acquisition mode and tracing mode by two processes.In tracing mode, only Need the frequency fluctuation for the treatment of very little；But when receiver is in acquisition mode, frequency departure can be with larger, it may be possible to sub- load The several times of wave spacing.
The task of first stage is sought to carry out coarse frequency estimation as soon as possible in receiver, and the capture for solving carrier wave is asked Topic；The task of second stage can exactly be locked and perform tracing task.Above-mentioned synchronous task is divided into the good of two stages Place is：Only need to consider the task of required execution in its moment due to the algorithm in each stage, therefore can set The larger free degree is introduced in meter synchronization structure.This also implies that, only needs to consider such as in (acquisition phase) in the first stage Where rough estimate carrier frequency in larger capture range, it is not necessary to how consider tracking performance；And in second stage (tracking Stage) in, it is only necessary to consider how to obtain tracking performance higher.
Sample synchronization：
Realize that the information at modulation /demodulation two ends is sampled on the same frequencies by adding pilot frequency information.
Timing synchronization：
Due to inserting Cyclic Prefix protection interval between OFDM symbol, thus OFDM symbol Timing Synchronization it is initial when Quarter can change in protection interval, without causing inter-carrier interference (ICI) and intersymbol interference (ISI).
Only when FFT computing windows are beyond character boundary, or fall into the amplitude of symbol and roll-off interval, can just cause ICI and ISI.Therefore, requirement of the ofdm system to timing synchronization can be relatively loose, but in multi-path environment, in order to Obtain optimal systematic function, it is thus necessary to determine that optimal Symbol Timing.Although the starting point of Symbol Timing can be in protection interval Any selection, but easily learn, the change of any Symbol Timing, can all increase sensitive journey of the ofdm system to delay spread Degree, therefore the patient delay spread of system institute will be lower than its design load.In order to as far as possible reduce this negative impact, it is necessary to Reduce the error of timing synchronization as far as possible.
The current timing synchronization on multicarrier system for proposing and carrier synchronization are mostly using insertion frequency pilot sign Method, this can cause the waste of bandwidth and power resource, reduce the validity of system.In fact, almost all of multicarrier System all eliminates intersymbol interference using the method for insertion protection interval.In order to overcome the shortcoming of frequency pilot sign waste of resource, We generally complete the maximal possibility estimation of timing synchronization and carrier frequency synchronization using the information entrained by protection interval Algorithm.
It is synchronously very crucial problem in ofdm system, can the quality of net synchronization capability directly influences OFDM technology just True modulation /demodulation data.In an ofdm system, there is the synchronization of various ranks：Carrier synchronization, timing synchronization and sample Value is synchronous, and the synchronization of each of which rank can all be impacted to ofdm system performance.
5. as shown in figure 3, to realize that 4,000,000 log well at a high speed communication, it is necessary in downhole telemetry unit 22, specially design one OFDM modulation panels 23 are planted, the log data that downhole sensor group 25 sends can be so modulated into the data flow of 4Mbit/s, Data are uploaded in logging cable 21.A kind of OFDM demodulation plate 21 is designed in surface acquisition system 20, the solution for realizing data Code.
The above is presently preferred embodiments of the present invention and its know-why used, for those skilled in the art For, without departing from the spirit and scope of the present invention, it is any based on technical solution of the present invention on the basis of equivalent change Change, simply replacement etc. obviously changes, belong within the scope of the present invention.

Claims (4)

1. 4,000,000 at a high speed well logging the communication technology, it is characterised in that use OFDM technology, realize the maximum 4Mbit/s of logging cable The high-speed transfer of data.
2. it is according to claim 1 4,000,000 at a high speed well logging the communication technology, it is characterised in that selected frequency band range be 12 K ~ 512 k, is divided into 128 sub-channels, the bit number average out to 8bit of each sub-channels, with a width of 500kHz, so maximum pass Defeated speed is exactly 8bit*500kHz=4Mbit/s, and the symbol time for being used is 256*1us, protection interval 0us.
3. to realize technology described in claim 1, it is necessary in downhole instrument acquisition system, specially design a kind of OFDM modulation Plate, realizes the coding of 4Mbit/s data, and a kind of OFDM demodulation plate is designed in ground system, the decoding for realizing data.
4. it is the technology for realizing described in claim 1, during log data is by OFDM modulation panels in the downhole instrument string, pseudorandom After coding, using RS codings, block interleaving, constellation mapping, Inverse Fast Fourier Transforms, then by Cyclic Prefix insertion algorithm, lead to Cross D/A converter and be converted into analog signal and be sent to 7000 meters of logging cables, information is uploaded to ground and demodulates by logging cable Plate is demodulated, during the demodulation data by after discretization, by synchronized algorithm, fast Fourier algorithm, circulation Become user data upload to ground system after prefix removal, channel equalization, demapping, deinterleaving, RS decodings, solution pseudorandomcode System software.
CN201610810510.4A 2016-09-08 2016-09-08 The 4000000 high speed well logging communication technologys Pending CN106789804A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112187695A (en) * 2020-09-30 2021-01-05 中国科学技术大学 FPGA channel pre-emphasis and equalization method and system based on OFDM high-speed logging telemetry system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1606298A (en) * 2004-11-12 2005-04-13 东南大学 Method for implementing full digital wireless communication system using fast Fourier transform
CN1988402A (en) * 2006-10-10 2007-06-27 东南大学 Method for realizing power line carrier communication system
CN101179356A (en) * 2007-11-28 2008-05-14 中国海洋石油总公司 Data transmitting, receiving method and device
CN201878187U (en) * 2010-11-24 2011-06-22 中国海洋石油总公司 OFDM (orthogonal frequency division multiplexing) high-speed logging telemetry system with echo canceling function
CN202850989U (en) * 2012-09-21 2013-04-03 中国海洋石油总公司 High speed data transmission system based on single-core logging cable

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1606298A (en) * 2004-11-12 2005-04-13 东南大学 Method for implementing full digital wireless communication system using fast Fourier transform
CN1988402A (en) * 2006-10-10 2007-06-27 东南大学 Method for realizing power line carrier communication system
CN101179356A (en) * 2007-11-28 2008-05-14 中国海洋石油总公司 Data transmitting, receiving method and device
CN201878187U (en) * 2010-11-24 2011-06-22 中国海洋石油总公司 OFDM (orthogonal frequency division multiplexing) high-speed logging telemetry system with echo canceling function
CN202850989U (en) * 2012-09-21 2013-04-03 中国海洋石油总公司 High speed data transmission system based on single-core logging cable

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112187695A (en) * 2020-09-30 2021-01-05 中国科学技术大学 FPGA channel pre-emphasis and equalization method and system based on OFDM high-speed logging telemetry system
CN112187695B (en) * 2020-09-30 2021-12-14 中国科学技术大学 FPGA channel pre-emphasis and equalization method and system based on OFDM high-speed logging telemetry system

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Application publication date: 20170531