CN102508297B - Accurate measurement and correction method and device of synchronous acquisition time errors of multiple codes - Google Patents
Accurate measurement and correction method and device of synchronous acquisition time errors of multiple codes Download PDFInfo
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Abstract
The invention belongs to the field of geophysical exploration and provides a signal transmission delay measurement model and a method. The magnitude of synchronous errors needing to be corrected can be accurately measured by adopting the model and the method. The invention provides an accurate measurement and correction method and device of synchronous acquisition time errors of multiple codes. The device is applied to a towline acquisition system. The system mainly comprises a control and processing center, a data preprocessing module and acquisition nodes, wherein the control and processing center generates a main clock. The device comprises a delay measurement module (DMM) and a delay correction module (DCM)_i, wherein i is equal to 1,2,...,n and means the i<th> acquisition node; the DMM is arranged in the data preprocessing module; and the DCM_i is arranged in the corresponding i<th> acquisition node. The method and the device are mainly applied to geophysical exploration.
Description
Technical field
The invention belongs to the geophysical survey field, particularly accurate measurement and the means for correcting of synchronous acquisition time errors of multiple codes.
Background technology
Ideally, in the earthquake towed cable acquisition system, all acquisition nodes (hereinafter to be referred as node) should receive at synchronization " uploading geological data order (be used for notify all nodes to upload the order of geological data) ", and synchronization is converted the geological data of completing is uploaded to and controls and processing enter.In traditional earthquake towed cable acquisition system, at towing cable, a synchronous acquisition major clock with high stability is set foremost, each node is synchronously changed simulating signal in the control of this synchronous acquisition major clock with under coordinating.But under actual conditions, " upload the geological data order " and control when being transferred to node or being transferred to another node from a node with data processing centre (DPC) from system, can produce transmission delay, and this transmission delay increases along with the increase (being the increase of transmission range) of number of nodes.Just because of the existence of this transmission delay, thereby make each node can not receive simultaneously " uploading the geological data order ".The moment that receives " uploading the geological data order " due to each node is different, is converted so the geological data of uploading is no longer synchronization the geological data of completing, and namely has the synchronous error that gathers.the synchronization accuracy that the seismic instrument of present main flow is indicated is Microsecond grade, but due to the data of actual acquisition and record take sampling point as unit, so the disposal route of first sampling point is the key of system synchronization acquisition precision, the synchronization accuracy of at present external main flow seismic survey towing cable is merely able to reach a sampling period, as System Four and ARIE, the synchronous acquisition precision of detection towing cable system that accounts for the French Sercel company of the main share in market also only has 0.25ms[1-3], therefore the actual acquisition synchronization accuracy of these instruments only has Millisecond (to see document [1] rowland soldier for details, Jia Yanfang. the impact [J] of the disposal route of first sampling point on synchronization accuracy. geophysical equipment, 2009, 19 (4): 219-220.[2] rowland soldier, Dong Shixue. research and analysis [J] when system for acquiring seismic data postpones. Jilin University's journal (geoscience version), 2005, 35 (S1): 62-65. document [3] Zhu Debing, flat interest is handsome, Zhu Ziqiang. the shallow seismic exploration data are intended the synchronous acquisition step-out time analysis and are put into practice [J]. Advances in Geophysics .2008, 23 (6): 1958-1962.).Continuous increase along with nodes in the organism on towing line for seismic exploration acquisition system, transmission delay is increasing, and the method in existing pertinent literature can only make the synchronization accuracy of collection reach Microsecond grade, and large like this synchronous error will be brought many adverse effects to the subsequent treatment of geological data.
Summary of the invention
For overcoming the deficiencies in the prior art, accomplish:
(1) provide a kind of signal transmission delay measurement model and method.By this model and method, can accurately measure the synchronous error amount that need to be corrected.
(2) based on described signal transmission delay measurement model, provide a kind of bearing calibration of synchronous error, the synchronous error that all nodes can be gathered seismic signal is eliminated fully, is 0 thereby make the synchronous error of collection.
for achieving the above object, the technical scheme that the present invention takes is, a kind of accurate measurement and means for correcting of synchronous acquisition time errors of multiple codes, be applied to the towing cable collection system, the towing cable collection system mainly comprises control and processing enter, data preprocessing module, acquisition node, control with processing enter and produce major clock, it is characterized in that, described device constitutes Time delay measurement module DMM, time-delay correction module DCM_i, i=1, 2, n, represent i acquisition node, Time delay measurement module DMM is arranged in data preprocessing module, time-delay correction module DCM_i is arranged in corresponding i acquisition node:
Time delay measurement module DMM is used for: (1) adopts inter-sync mode that master clock signal is modulated to order data stream, and transmits to each acquisition node by signal wire; (2) measurement module DMM sends a characteristic signal that is used for measuring transmission delay, then records and preserve down this characteristic signal through after all acquisition nodes, is passed back to the time of Time delay measurement module DMM; (3) complete the calculating process of transmission delay correcting value; (4) adopt the mode of asynchronous communication that the transmission delay correcting value is transferred in each corresponding node; (5) realize the duty with disable of enabling of upward signal driver;
Time-delay correction module DCM_i mainly completes following functions: (1) receiving synchronous information and order data; (2) command decode and control; (3) reception of time-delay correcting value and the correction of transmission delay.
Be provided with timer, computing module in Time delay measurement module DMM, at first by Time delay measurement module DMM at t
0Constantly send out a characteristic signal, and meanwhile, the timer that starts in Time delay measurement module DMM begins timing, acquisition node i, i=1,2, n after receiving this characteristic signal, transfers back to this characteristic signal in Time delay measurement module DMM, when Time delay measurement module DMM receives this by the characteristic signal passed back, write down the corresponding moment, then carry out corresponding mathematical operation by computing module, calculate transmission delay amount Δ t
i
Time-delay correction module DCM_i, when i node receive upload the geological data order after, i=1,2 ..., n starts time-delay correction module DCM_i and carries out Δ t
n-Δ t
iThen the time-delay of time quantum starts the transport process of geological data in self acquisition node by signal wire, it is Δ t that last node receives the time-delay of uploading the geological data order
n, Δ t
iExpression is sent characteristic signal from Time delay measurement module DMM and is transmitted back to this characteristic signal the transmission delay amount that Time delay measurement module DMM produces.
A kind of accurate measurement and bearing calibration of synchronous acquisition time errors of multiple codes realize by means of the described device of power 1, and comprise the following steps:
The first step is to determine the signal form of characteristic signal: signal is named as Signal_g, and wherein Signal_g is configured to cycle T
SgBe infinity, have the unipolarity square-wave signal of the positive pulsewidth of 20ns;
Second step is to be described in detail signal to be sent to the measuring process of the transmission delay that each acquisition node produces by Time delay measurement module DMM25:
Being provided with a clock period in Time delay measurement module DMM is T
CLKCounter CTer, DMM is at t for the Time delay measurement module
0Constantly start CTer and begin counting, and send simultaneously the Signal_g signal, after time-delay correction module DCM_1 receives Signal_g, on the one hand the Signal_g signal is passed to the 2nd node, after on the other hand the Signal_g signal being carried out time-delay that duration is TT, be transmitted back to Time delay measurement module DMM, when Time delay measurement module DMM detects by the Signal_g of the 1st node passback, preserve the count value CTer_t_1 of counter; The rest may be inferred, when Time delay measurement module DMM detects by the Signal_g of i node passback, preserves the count value CTer_t_i of counter; Suppose that it is T by total transmission delay that the FPGA internal logic produces that the Signal_g signal is sent to i node from Time delay measurement module DMM25
Di_T, and suppose that it is T that the Signal_g signal passes back to from i node the total transmission delay that is produced by the FPGA internal logic Time delay measurement module DMM25
ID_T, the Signal_g signal is sent to i node transmission delay from Time delay measurement module DMM and is:
The 3rd step was the trimming process of all acquisition node transmission delays:
By above-mentioned time delay correction method as can be known, the time-delay correcting value T of each acquisition node
iFor:
Time delay measurement module DMM calculates the delay time correcting value T of each node by following formula
i, the node address of supposing node i is address_i, i=1, and 2 ..., Time delay measurement module DMM adopts point-to-point asynchronous communication means with the time-delay correcting value T of each node
iBe sent in the acquisition node of each corresponding node address.
The present invention has following technique effect:
(1) break through existing seismic instrument and gather the synchronous acquisition error of seismic signal up to the present situation of hundreds of microsecond, the synchronous error that the present invention can gather multinode seismic signal is reduced to the magnitude of nanosecond.
(2) in the situation that transmission signal line in not increase system, utilize in system the transmission signal line 32,35 that itself has, 53 and in conjunction with the special transmission delay measurement model that designs in the present invention, realize that " uploading the geological data order " from the data preprocessing module 18s, is transferred to the accurate measurement of the transmission delay (synchronous acquisition error) of all nodes.Time delay measurement scheme in the present invention can the ingenious design feature of existing system of utilizing be carried out Time delay measurement and correction, and the expense of system is little, and structure is ingenious, realizes simple.
(3) adopt the method that the transmission delay of all nodes is registered to the transmission delay of last node, realized the accurate correction of transmission delay, the method is simple.
(4) to the not restriction of quantity of node, how much quantity of pipe node do not have, and uses the method all can carry out accurate measurement and correction to the transmission delay (synchronous acquisition error) of all nodes, thereby realize the synchronous acquisition of all nodes in system.
Description of drawings
Fig. 1 illustrates towing cable collection general system proposal block diagram of the present invention.
Fig. 2 illustrates the model that is used for measuring transmission delay in the present invention.
Fig. 3 illustrates the structure of data preprocessing module in the present invention.
Fig. 4 illustrates the structure of acquisition node in the present invention.
Fig. 5 illustrates amount of delay and the trimming process of each node of the present invention.
Fig. 6 illustrates the form of Signal_g signal in the present invention.
Fig. 7 illustrates the data frame format of time-delay correcting value in the present invention.
In Fig. 1: 1 for controlling and processing enter; 2 is sound source; 3 is sound wave; 4 is towing cable head connector; 5 is data preprocessing module; 6 is the sea level; 7 is system control command and synchronous acquisition major clock downlink transfer link; 8 is data and state uplink link; 9,10,11,12 is sensor; 13 is sea bed; 14 is acquisition node; 15 is the afterbody connector; 16 is tail buoy.
In Fig. 2: 17 for controlling and processing enter; 18 is data preprocessing module; 19,20,21 and 22 is acquisition node.
In Fig. 3: 23 are order, data and status bus; 24 is major clock; 25 is Time delay measurement module DMM; 26 is that data, state receive and pretreatment module; 27 and 28 is signal wire; 29 is the downgoing signal driver; 30 is the upward signal driver; 31 is the RS485 chip; 32 are the transmission twisted-pair feeder; 33 control signal wires that enable for upper line driver 30; 34 is the transmission of seismic data line.
In Fig. 4: 35 and 53 is twisted-pair feeder; 36 and 50 is the upward signal driver; 37 and 51 is the downgoing signal driver; 38 and 52 are RS485 driving chip; 39,40,48 and 49 is signal wire; 41 is the upload control module; 42 are the time-delay correction module; 43 are major clock recovery phase-locked loop pll; 44 is signal wire; 45 are geological data reception and forwarding module; 46 is the FGPA module in acquisition node; 47 is the analog to digital conversion adc circuit; 54 is the transmission of seismic data line; 55 control signal wires that enable for downlink drive device 37; 56 control signal wires that enable for upper line driver 50.
In Fig. 5: 57 spread out of the moment of " uploading the geological data order " for data preprocessing module 18; 58 is that the 1st acquisition node 19 receives the moment of " uploading the geological data order "; 59 is that the 2nd acquisition node 20 receives the moment of " uploading the geological data order "; 60 is that n acquisition node 22 receives the moment of " uploading the geological data order ".61 are the 1st moment that acquisition node 18 is uploaded geological data after calibrated; 62 are the 2nd moment that acquisition node 19 is uploaded geological data after calibrated; 63 are n moment that acquisition node 22 is uploaded geological data after calibrated.
Fig. 6 is the form of Signal_g signal.
In Fig. 7: 64 data frame formats for the time-delay correcting value.
Embodiment
For overcoming the aforementioned deficiency of prior art, the technical matters that the present invention mainly solves is: (1) overcomes the method for available technology adopting guestimate and estimates the large shortcoming of transmission delay amount time error, and a kind of transmission delay measurement model and method are provided.By this model and method, can accurately measure the signal transmission delay amount (the synchronous acquisition margin of error) that produces when " uploading the geological data order " is transferred to each node from controlling with processing enter.(2) only has the problem of Microsecond grade for great deal of nodes synchronous acquisition precision in prior art, based on the transmission delay measurement model described in (1), a kind of bearing calibration of synchronous error is provided, the synchronous error of all node collections can be eliminated fully, be 0 thereby make the synchronous error of collection.
The technical solution used in the present invention is, accurately measures each acquisition node and uploads the method for geological data time error and the bearing calibration that these time errors are eliminated fully, comprises the following steps:
The first step is to determine the towing cable collection general system proposal.
Towing cable collection general system proposal block diagram is mainly by the control in towboat and processing enter 1, sound source 2, towing cable head connector 4, data preprocessing module 5, system control command and synchronous acquisition major clock downlink transfer link 7, data and state uplink link 8, sensor 9, back end 14, afterbody connector 15 and tail buoy 16 form.
Second step is the model that proposes measuring-signal transmission delay in the towing cable collection system.
The measurement model of signal transmission delay by the 1st node 19, the 2nd node 20, an i node 21 ..., n the acquisition node such as a n node 22, control and processing enter 17, data preprocessing module 18 forms, as shown in Figure 2.Described data preprocessing module 18 is mainly by major clock 24, Time delay measurement module DMM (Delay Measurement Module) 25, data, state receive and pretreatment module 26, and upward signal driver 29 and downgoing signal driver 30 form, as shown in Figure 3.Major clock 24 is provided by a temperature compensating crystal voltage controlled oscillator with high precision, high stability and low phase error.Time delay measurement module DMM25 mainly completes following function: (1) adopts inter-sync mode that master clock signal is modulated in order data stream, and transmits to each acquisition node by signal wire 27; (2) measurement module DMM25 sends a characteristic signal that is used for measuring transmission delay, then records and preserve down this characteristic signal through after all nodes, is passed back to the time of Time delay measurement module DMM25; (3) complete the calculating process of transmission delay trimming process; (4) adopt the method for asynchronous communication number that the transmission delay correcting value is transferred in each corresponding node; (5) realize the duty with disable of enabling of upward signal driver 30.Data, state receive with pretreatment module 26 under the control of control and processing enter 17, realize reception and the preprocessing function of geological data and acquisition node duty.Upward signal driver 29 and downgoing signal driver 30 are comprised of a slice RS485 interface chip 31, by connecting cleverly, only needing to have realized the just function of the up and descending timesharing transmission of energy settling signal of a pair of transmission twisted-pair feeder 32.
Inner structure and the function of all acquisition nodes are identical, as shown in Figure 4.Node i (node_i, i=1,2,, n) 21 mainly by driving chip 38, upload control module UCM_i (Uplink Control Module) 41, time-delay correction module DCM_i (DelayCorrection Module) 42, digital phase-locked loop PLL43, analog to digital conversion adc circuit 47 drives chip 52 and forms.Drive the descending and up transmission that chip 38 and 52 is used for the realization character signal.Upload control module UCM_i (i=1,2 ..., n) the 41 passback control functions of mainly completing characteristic signal.Time-delay correction module DCM_i (i=1,2 ..., n) 42 mainly complete following functions: (1) receiving synchronous information and order data; (2) command decode and control; (3) reception of time-delay correcting value and the correction of transmission delay.Phase-locked loop pll 43 is used for recovering master clock signal from the order data stream.Analog to digital conversion adc circuit 47 is used for converting the earthquake simulation signal to the earthquake digital signal.Geological data receives with forwarding module 45 and receives on the one hand the geological data that self acquisition node receives, and receives on the other hand the geological data that the next stage acquisition node sends; Then will pass upwards acquisition node after these geological data packings.
Described other node, as identical with i the described 26S Proteasome Structure and Function of node 21 in the 1st node 19, the 2nd node 20, a n node 22 and other n-3 that is omitted node, do not enumerate here.
The 3rd step was according to the above, determined measurement and the bearing calibration of the time error of each node transmission seismic signal.
In described towing cable collection system between different nodes the time error of transmission geological data because " uploading the geological data order " transmission in transmission line and each node produces.Suppose that the moment that spreads out of in " uploading the geological data order " Time delay measurement module DMM25 from data preprocessing module 18 is t0, as shown in Figure 5, due to transmission delay, the moment that acquisition node 1 receives " uploading the geological data order " is not t
0Constantly, but t
1Constantly, the rest may be inferred, and acquisition node n is at t
nConstantly receive " uploading the geological data order ".Obviously, if these transmission delays are not proofreaied and correct processing, survey each acquisition node after receiving " uploading the geological data order ", the moment of transmitting geological data is different certainly, namely can produce the time error of multinode synchronous acquisition seismic signal.In order to overcome this synchronous acquisition error, the present invention proposes a kind of bearing calibration of synchronous acquisition time error.The prerequisite of this bearing calibration is to know that signal is from pretreatment module, be transferred to the accurate transmission delay amount of each node, so at first the present invention is described in detail the model of measuring transmission delay in the above-mentioned first step and second step, and the transmission delay measurement model by proposing in the present invention, can accurately measure Δ t in Fig. 5
1～Δ t
nSize.The measuring process of transmission delay is as follows: as shown in Figure 2, at first by Time delay measurement module DMM25 at t
0Constantly send out a characteristic signal, and meanwhile, the timer that starts in Time delay measurement module DMM25 begins timing.Acquisition node i (i=1,2, n) receive this characteristic signal by ai → di path after, to this characteristic signal be transferred back in Time delay measurement module DMM25 by di → bi → ai path, when Time delay measurement module DMM25 receives this by the characteristic signal passed back, write down the corresponding moment, then by corresponding mathematical operation, calculate transmission delay amount Δ t
iIllustrate: the transmission delay that produces on twisted-pair feeder due to different frequency signals changes very small, so the present invention can think that the transmission delay that different frequency signals produces is constant on twisted-pair feeder, thus, we can transmit the time-delay of time-delay that characteristic signal produces and the transmission generation of " uploading the geological data order " on twisted-pair feeder identical, are all namely Δ t
i
The below carries out the elaboration of transmission delay bearing calibration.As shown in Figure 5, last node receives the time-delay Δ t of " uploading the geological data order "
nIt is different that maximum, each node are uploaded the moment of self geological data, namely has the synchronous acquisition error; So the present invention proposes a kind of bearing calibration of synchronous acquisition error.Method is: arrange one and proofread and correct time delay module in the time-delay correction module DCM of each acquisition node; When i (i=1,2 ..., after n) individual node receives " uploading the geological data order ", start the correction time delay module and carry out Δ t
n-Δ t
iThen the time-delay of time quantum starts the transport process of geological data in self acquisition node, as shown in Figure 4 by signal wire 44.After the transmission delay amount of all nodes was corrected, the moment that each acquisition node is uploaded self geological data all was corrected to t
nConstantly, namely all acquisition nodes all at t
nConstantly begin to upload the geological data of self.
After said process was proofreaied and correct, the moment of all node acquiring seismic datas was identical, namely realizes real synchronous acquisition.
The advantage of synchronous acquisition major clock transmission delay measure portion of the present invention is: (1) is broken through existing seismic instrument and is gathered the synchronous acquisition error of seismic signal up to the present situation of hundreds of microsecond, and the synchronous error that the present invention can gather multinode seismic signal is reduced to the magnitude of nanosecond.(2) in the situation that transmission signal line in not increase system, utilize in system the transmission signal line 32,35 that itself has, 53 and in conjunction with the special transmission delay measurement model that designs in the present invention, realize that " uploading the geological data order " from the data preprocessing module 18s, is transferred to the accurate measurement of the transmission delay of all nodes.Time delay measurement scheme in the present invention can the ingenious design feature of existing system of utilizing be carried out Time delay measurement and correction, and the expense of system is little, and structure is ingenious, realizes simple.(3) adopt the method that the transmission delay of all nodes is registered to the transmission delay of last node, realized the accurate correction of transmission delay, the method is simple.(4) to the not restriction of quantity of node, how much quantity of pipe node do not have, and uses the method all can carry out accurate measurement and correction to the transmission delay of all nodes, thereby realize the synchronous acquisition of all nodes in system.
Further illustrate the present invention below in conjunction with drawings and Examples.
Technical scheme of the present invention is first to accurately measure by the Time delay measurement model " uploading the geological data order " is sent to each node from data preprocessing module transmission delay.Then by the transmission delay bearing calibration, each node is uploaded the time correction of self geological data to synchronization.
The first step is to determine the signal form of characteristic signal, and this signal is named as Signal_g.Wherein Signal_g is configured to cycle T
SgBe infinity, have the unipolarity square-wave signal of the positive pulsewidth of 20ns, as shown in Figure 6.
Second step is to be described in detail signal to be sent to the measuring process of the transmission delay that each acquisition node produces by Time delay measurement module DMM25.
Being provided with a clock period in Time delay measurement module DMM25 is T
CLKCounter CTer.DMM25 is at t for the Time delay measurement module
0Constantly start CTer and begin counting, and send simultaneously the Signal_g signal, signal is sent to the 1st the time-delay correction module DCM_1 in node 19 through a0 → d0 → e0 → a1 → d1.After time-delay correction module DCM_1 receives Signal_g, on the one hand the Signal_g signal is passed to the 2nd node 20 along d1 → e1 → a2 path, after on the other hand the Signal_g signal being carried out time-delay that duration is TT, then be transmitted back to Time delay measurement module DMM25 along d1 → b1 → a1 → e0 → c0 → a0 path.When Time delay measurement module DMM25 detects by the Signal_g of the 1st node 19 passbacks, preserve the count value CTer_t_1 of counter.In like manner, after time-delay correction module DCM_2 receives Signal_g, on the one hand the Signal_g signal is passed to the 3rd node along d2 → e2 → a3 path, after on the other hand the Signal_g signal being carried out time-delay that duration is TT, then along being transmitted back to Time delay measurement module DMM25 along d2 → b2 → a2 → e1 → c1 → b1 → a1 → e0 → c0 → a0 path.When measurement module DMM25 detects by the Signal_g of the 2nd node 20 passbacks at that time, preserve the count value CTer_t_2 of counter.The rest may be inferred, when Time delay measurement module DMM25 detects by the Signal_g of i node 21 passbacks, preserves the count value CTer_t_i of counter.
Illustrate: in this Time delay measurement model, after Time delay measurement module DMM25 sends out the Signal_g signal, the Signal_g signal that Time delay measurement module DMM25 receives for the 1st time is through a0 → d0 → e0 → c0 → a0 path passback, rather than returned by acquisition node, therefore counter CTer does not preserve corresponding count value when receiving the Signal_g signal the 1st time.In like manner, upload control module UCM_i (i=1,2, n) the Signal_g signal that receives for the 1st time is through di → ei → ci path passback, rather than through the passback of subordinate acquisition node, therefore upload control module UCM_i does not return forwarding to the Signal_g signal that receives for the 1st time, but return forwarding since the 2nd time.Delayed time before correction module DCM passback in order to guarantee the Signal_g signal, DMM has transmitted the Signal_g signal and has completed, so before DCM passback Signal_g signal, first the Signal_g signal being produced duration is the time-delay of TT, TT can be arranged between 500ns-lus.
The Signal_g signal is passed to di point (Fig. 2) from the ai point, the transmission delay t that produces
Ai → diExpression; The expression that uses the same method of other transmission delay.Suppose that the a0 point of Signal_g signal from Time delay measurement module DMM25 is sent to i the di point in node 21, the total transmission delay that is produced by signal driver and transmission line is T
Di_L, the total transmission delay that is produced by the FPGA internal logic is T
Di_T:
T
Di_L＝t
e0→a1+t
e1→a2+t
e2→a3+…+t
e(i-1)→ai (1)
T
Di_T＝t
a0→d0→e0+t
a1→d1→e1+…+t
a(i-1)→d(i-1)→e(i-1)+t
ai→di (2)
Suppose that the di point of Signal_g signal from acquisition node i passes back to the a0 point in Time delay measurement module DMM25, the total transmission delay that is produced by signal driver and transmission line is T
ID_L, the total transmission delay that is produced by the FPGA internal logic is T
ID_T:
T
iD_L＝t
ai→e(i-1)+…+t
a3→e2+t
a2→e1+t
a1→e0 (3)
T
iD_T＝t
di→bi→ai+t
e(i-1)→c(i-1)→a(i-1)+…+t
e2→c2→a2+t
e1→c1→a1+t
e0→c0→a0+i×TT (4)
By the above Time delay measurement model as can be known, the Signal_g signal is sent to the di point from the a0 point, and then passes back to the a0 point from the di point, total transmission delay T
Totel_iFor:
T
Totel_i＝T
Di_L+T
Di_T+T
iD_L+T
iD_T (5)
Yi Zhi:
T
Totel_i＝CTer_t_i×T
CLK (6)
Because signal transmssion line is same signal transmssion line, therefore have:
T
Di_L＝T
iD_L (7)
Because the hardware of all acquisition nodes is identical with processing procedure, therefore can think:
t
a1→d1→e1＝t
a2→d2→e2＝…＝t
a(i-1)→d(i-1)→e(i-1) (8)
(2) formula is written as at this moment:
T
Di_T＝t
a0→d0→e0+(i-1)t
a1→d1→e1+t
ai→di (9)
In like manner, can get:
t
e1→c1→a1＝t
e2→c2→a2＝…＝t
e(i-1)→c(i-1)→a(i-1) (10)
(4) formula is written as at this moment:
T
iD_T＝t
di→bi→ai+(i-1)t
e1→c1→a1+t
e0→c0→a0+i×TT (11)
In FPGA, can obtain t by sequential emulation
A0 → d0 → e0, t
A1 → d1 → e1, t
Ai → di, t
Di → bi → ai, t
E1 → c1 → a1, t
E0 → c0 → a0Exact value with TT.These known quantities are updated in (9) formula and (11) formula can calculate T
Di_TWith T
ID_TValue, and then can try to achieve T in conjunction with (5), (6) and (7) formula
Di_LValue.Use T
A0 → diExpression Signal_g signal is sent to from the a0 point total transmission delay that di is ordered:
That is:
In like manner, the Signal_g signal adopts said method all can obtain one by one from the transmission delay that the a0 point is sent to other acquisition node.
The transmission delay K that twisted-pair feeder is every meter
trAs shown in (14) formula.
Wherein, ξ
rBe Effective relative permittivity.During with the variation of environment temperature, ξ
rChange very little, so ignore in the present invention variation of ambient temperature to the impact of Double-strand transmission time-delay.Equally, by (13) formula as can be known, twist paired signal line is the same to the transmission delay of different frequency signals, so the transmission delay of the characteristic signal Signal_g that calculates by above-mentioned formula equates with the transmission delay of actual " uploading the geological data order " signal.
The 3rd step was the trimming process of all acquisition node transmission delays.
By time delay correction method in above-mentioned Fig. 5 as can be known, the time-delay correcting value T of each acquisition node
iFor:
Time delay measurement module DMM25 calculates the delay time correcting value T of each node by (15) formula
iThe node address of supposing node i be address_i (i=1,2 ...), Time delay measurement module DMM25 adopts point-to-point asynchronous communication means with the time-delay correcting value T of the data frame structure 64 in Fig. 7 with each node
iBe sent in the acquisition node of each corresponding node address.
When each acquisition node receives time-delay correcting value T
iAfter, it is kept in node.Arrange one and proofread and correct time delay module in the time-delay correction module DCM of each acquisition node; When i (i=1,2 ..., after n) individual node receives " uploading the geological data order ", start the correction time delay module and carry out Δ t
n-Δ t
iThen the time-delay of time quantum starts the transport process of geological data in self acquisition node, as shown in Figure 4 by signal wire 44.After the transmission delay amount of all nodes was corrected, the moment that each acquisition node is uploaded self geological data all was corrected to t
nConstantly, namely all acquisition nodes all at t
nConstantly begin to upload the geological data of self, and reach the target of the precision synchronous acquisition of multisensor.
Power supply to system describes: in system, all power modules all embody in the drawings, but all modules that need to power all adopt corresponding power module to power, needed energy when can obtain work.
Claims (2)
1. accurate measurement and the means for correcting of a synchronous acquisition time errors of multiple codes, be applied to the towing cable collection system, the towing cable collection system mainly comprises control and processing enter, data preprocessing module, acquisition node, control with processing enter and produce major clock, it is characterized in that, described device constitutes Time delay measurement module DMM, time-delay correction module DCM_i, i=1,2,, n represents i acquisition node, Time delay measurement module DMM is arranged in data preprocessing module, and time-delay correction module DCM_i is arranged in corresponding i acquisition node:
Time delay measurement module DMM is used for: (1) adopts inter-sync mode that master clock signal is modulated to order data stream, and transmits to each acquisition node by signal wire; (2) Time delay measurement module DMM sends a characteristic signal that is used for measuring transmission delay, then records and preserve down this characteristic signal through after all acquisition nodes, is passed back to the time of Time delay measurement module DMM; (3) complete the calculating process of transmission delay correcting value; (4) adopt the mode of asynchronous communication that the transmission delay correcting value is transferred in each corresponding node; (5) realize the duty with disable of enabling of upward signal driver;
Time-delay correction module DCM_i mainly completes following functions: (1) receiving synchronous information and order data; (2) command decode and control; (3) reception of time-delay correcting value and the correction of transmission delay;
Be provided with timer, computing module in Time delay measurement module DMM, at first by Time delay measurement module DMM at t
0Constantly send out a characteristic signal, and meanwhile, the timer that starts in Time delay measurement module DMM begins timing, acquisition node i, i=1,2, n after receiving this characteristic signal, transfers back to this characteristic signal in Time delay measurement module DMM, when Time delay measurement module DMM receives this by the characteristic signal passed back, write down the corresponding moment, then carry out corresponding mathematical operation by computing module, calculate transmission delay amount Δ t;
Time-delay correction module DCM_i, when i node receive upload the geological data order after, i=1,2 ..., n starts time-delay correction module DCM_i and carries out Δ t
n-Δ t
iThen the time-delay of time quantum starts the transport process of geological data in self acquisition node by signal wire, it is Δ t that last node receives the time-delay of uploading the geological data order
n, Δ t
iExpression is sent characteristic signal from Time delay measurement module DMM and is transmitted back to this characteristic signal the transmission delay amount that Time delay measurement module DMM produces.
2. accurate measurement and the bearing calibration of a synchronous acquisition time errors of multiple codes, is characterized in that, realizes by means of the described device of claim 1, and comprise the following steps:
The first step is to determine the signal form of characteristic signal: signal is named as Signal_g, and wherein Signal_g is configured to cycle T
SgBe infinity, have the unipolarity square-wave signal of the positive pulsewidth of 20ns;
Second step is to be described in detail signal to be sent to the measuring process of the transmission delay that each acquisition node produces by Time delay measurement module DMM:
Being provided with a clock period in Time delay measurement module DMM is T
CLKCounter CTer, DMM is at t for the Time delay measurement module
0Constantly start CTer and begin counting, and send simultaneously the Signal_g signal, after time-delay correction module DCM_1 receives Signal_g, on the one hand the Signal_g signal is passed to the 2nd node, after on the other hand the Signal_g signal being carried out time-delay that duration is TT, be transmitted back to Time delay measurement module DMM, when Time delay measurement module DMM detects by the Signal_g of the 1st node passback, preserve the count value CTer_t_1 of counter; The rest may be inferred, when Time delay measurement module DMM detects by the Signal_g of i node passback, preserves the count value CTer_t_i of counter; Suppose that it is T by total transmission delay that the FPGA internal logic produces that the Signal_g signal is sent to i node from Time delay measurement module DMM
Di T, and suppose that it is T that the Signal_g signal passes back to from i node the total transmission delay that is produced by the FPGA internal logic Time delay measurement module DMM
ID_T, the Signal_g signal is sent to i node transmission delay from Time delay measurement module DMM and is:
The 3rd step was the trimming process of all acquisition node transmission delays:
By above-mentioned time delay correction method as can be known, the time-delay correcting value T of each acquisition node
iFor:
Time delay measurement module DMM calculates the delay time correcting value T of each node by following formula
i, the node address of supposing node i is address_i, i=1, and 2 ..., n, Time delay measurement module DMM adopts point-to-point asynchronous communication means with the time-delay correcting value T of each node
iBe sent in the acquisition node of each corresponding node address.
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| CN106291752B (en) * | 2015-05-25 | 2018-05-29 | 云南航天工程物探检测股份有限公司 | Seismic detector system delay testing method |
| CN105068121A (en) * | 2015-07-30 | 2015-11-18 | 吉林大学 | Underground multi-node signal acquisition synchronous error correction device and method |
| US10677946B2 (en) * | 2016-06-30 | 2020-06-09 | Magseis Ff Llc | Seismic surveys with optical communication links |
| CN106443420B (en) * | 2016-08-30 | 2019-11-15 | 哈尔滨工业大学 | A kind of spacecraft information process unit Radiation Degeneration measuring device and method |
| CA3055089A1 (en) * | 2017-03-03 | 2018-09-07 | Schlumberger Canada Limited | Seismic sensor system with microelectromechanical systems ("mems") oscillator clock |
| JP2019101480A (en) * | 2017-11-28 | 2019-06-24 | オムロン株式会社 | Control device and control method |
| CN111083309B (en) * | 2018-10-18 | 2022-04-01 | 北京魔门塔科技有限公司 | Time alignment method of multi-sensor data and data acquisition equipment |
| CN109413733B (en) * | 2018-10-24 | 2021-04-23 | 济南格林信息科技有限公司 | Synchronous timing method, gateway, sensing node and system for information acquisition of sensing network |
| CN112711075B (en) * | 2019-10-25 | 2024-03-26 | 中国石油天然气集团有限公司 | Clock calibration system of marine seismic node |
| CN116009376A (en) * | 2022-09-29 | 2023-04-25 | 深圳越登智能技术有限公司 | Carry chain timing calibration method, device, equipment and storage medium |
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