CN102299743B - Post-compensation method for transmission time delay during optical fiber time transmission - Google Patents
Post-compensation method for transmission time delay during optical fiber time transmission Download PDFInfo
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Abstract
The invention relates to a post-compensation method for transmission time delay during optical fiber time transmission. The method comprises the following steps of: measuring bidirectional closed loop transmission delay deltaT during the optical fiber time transmission, calculating unidirectional transmission delay during the optical fiber time transmission, performing post-compensation on time transmission 1pps, and recoding and modulating a time signal at a user receiving end. Next-level time transmission is performed by the same method, so that cascade connection can be conveniently performed, and transmission time is remotely and accurately synchronized. Compared with the conventional pre-compensation method, the post-compensation method has the advantages that: different time information advance is not required to be set according to different levels, and pre-compensation devices of different levels are not needed, so the method is easy and convenient to operate; and the method has the advantages that the method is simple and practical, is high in reliability, and can be popularized and used in the optical fiber time transmission.
Description
Technical field
The invention belongs to temporal frequency transmission technique field in electronic information science, be specifically related to the compensation method of optical fiber time transmission propagation time delay.
Background technology
Temporal frequency delivery applications field in electronic information science, optical fiber time transmission adopts transmission delay compensation method to eliminate the time delay of transmission path and the drift that environmental factor causes, the high-precision time synchronized of real-time implementation.The compensation that Optical Fiber Transmission postpones is the optical fiber time transmission path based on becoming a closed loop, transmit transmitting terminal in the time, measure the propagation delay time of closed loop path, and think that the delay in round-trip transmission path is identical, therefore getting the half of the propagation delay time of closed loop path, is exactly to transmit transmitting terminal from the time to postpone to the one-way transmission of user's receiving terminal.Postpone according to this one-way transmission again, the time signal that is transferred to user's receiving terminal is compensated, realize the synchronous of remote optical fiber time.
The compensation method of propagation time delay is at present to adopt transmission delay pre-compensating method.Its concrete way is: transmits transmitting terminal in the time, postpones according to measuring the one-way transmission of calculating, and the lead of pps pulse per second signal in the mobile time signal of transmitting, this lead is to postpone to decide according to measuring the one-way transmission of calculating.Through the time signal of pre-compensating, in the time being delivered to user's receiving terminal, will obtain one with the pps pulse per second signal that transmits preamble.In fact, time signal, in pre-compensating implementation process, moves pps pulse per second signal backward, and the one-period that amount of movement is pulse per second (PPS) deducts one-way transmission to postpone.Like this, the time signal through pre-compensating receiving at user side, is actually the time signal that has postponed the cycle.For the pps pulse per second signal in time signal, the pps pulse per second signal that user's receiving terminal receives is synchronizeed with the pps pulse per second signal of transmitting terminal, but for the temporal information in time coding signal, still retains original temporal information.For example, referring to Fig. 2, the temporal information being sent out is 9:35:47 on Thursday on March 24th, 2011, and in Fig. 2, year, month, day, week are omitted.After pre-compensating, be delivered to user side, remain 9:35:47, in fact the time is 9:35:48.The time that user side receives, lagged one second than the actual time.This situation, for point-to-point, can shift to an earlier date one second by the temporal information of transmission in the time of pre-compensating.At transmitting terminal, be 9:35:48 by set of time, just can ensure that the temporal information that user side receives synchronizes with transmitting terminal.But for multiple cascading networks, just form difficulty.If there is N level to connect, according to different stage, different temporal information leads is set, just need the pre-compensation means of different stage, user's receiving terminal can only receive other time signal at the corresponding levels.Like this, operation is got up pretty troublesome, very loaded down with trivial details.
Summary of the invention
Technical problem to be solved by this invention is the shortcoming of the compensation method that overcomes above-mentioned propagation time delay, provides a kind of and can arbitrarily carry out cascade, realizes the synchronous optical fiber time of remote optical fiber time and transmit the post-equalization method of propagation time delay.
Solving the problems of the technologies described above adopted technical scheme is made up of following step:
1, the measuring optical fiber time is transmitted Bidirectional closed-loop transmission delay Δ T
Transmit control end in the time, reference time signal and 1pps signal that atomic clock is come, encoded modulators modulate becomes radiofrequency signal, and radiofrequency signal is that λ 1 laser 1 is modulated into light signal through wavelength, wavelength be λ 1 light signal through wavelength division multiplexer 1 feed-in optical fiber, through Optical Fiber Transmission to user's receiving terminal.At user's receiving terminal, wavelength X 1 light signal is through wavelength division multiplexer 2, then is demodulated into radiofrequency signal through optical-electrical converter 2, and the laser 2 that radiofrequency signal is λ 2 by wavelength is again modulated to light signal again.In order to improve precision, reduce the asymmetry of transmission delay, wavelength is that the light signal of λ 1 and wavelength are that the dense wavelength division multiplexing method that the light signal of λ 2 adopts wavelength to be less than 1nm is transmitted.Wavelength is that the light signal of λ 2 transmits control end through wavelength division multiplexer 2 and the optical fiber time that passes back to again.Transmit control end in the time, the wavelength being returned by optical fiber and wavelength division multiplexer 1 is λ 2 light signals, demodulates radiofrequency signal by optical-electrical converter 1, and radiofrequency signal demodulates the 1pps signal of fibre-optical closed-loop passback again through demodulating and decoding device 1; Give time-interval counter with reference to 1pps signal and passback 1pps signal simultaneously, carry out time difference measurement, time-interval counter output data are fibre-optical closed-loop transmission delay Δ T.
Above-mentioned wavelength is that the light signal of λ 1 and wavelength are that the wave-length coverage of the light signal of λ 2 is 1550nm or 1331nm universal optical fibre communication band.
2, calculate optical fiber time and transmit one-way transmission delay
Transmit control end in the time, the fibre-optical closed-loop transmission delay data Δ T of time-interval counter output is to coding demodulator 1, and the equipment that closed loop transmission delayed data Δ T includes time transmission control end postpones Δ t
tpostpone Δ t with the equipment of user's receiving terminal
r, this equipment is calibrated mensuration before postponing to transmit in the time.In order to improve the measurement computational accuracy of transmission delay, wavelength is that light signal and the wavelength of λ 1 is the light signal employing dense wavelength division multiplexing method of λ 2, can think that the transmission delay of two wavelength is identical.Coding demodulator 1 calculates by following formula:
In formula, Δ τ is that one-way transmission postpones, Δ t
tthat the equipment that transmits control end the time postpones, Δ t
rthe equipment that is user's receiving terminal postpones, and Δ T is that closed loop transmission postpones.When receiving time-interval counter, coding demodulator 1 sends here after Δ T data, show that as calculated transmitting control end from the time postpones Δ τ to the one-way transmission of user's receiving terminal, one-way transmission postpones Δ τ and reference time signal, 1pps signal carries out coded modulation by coding demodulator 1 together, and is sent to user's receiving terminal.
3, the time is transmitted the post-equalization of 1pps
At user's receiving terminal, the radiofrequency signal that optical-electrical converter 2 is exported is given demodulating and decoding device 2, demodulating and decoding device 2 is exported 1pps signal, time information signal, one-way transmission delay Δ τ, delay compensator receives after 1pps signal and one-way transmission delayed data Δ τ, compensates receiving 1pps signal.So-called compensation, is actually the 1pps signal leading edge receiving is postponed to 1s-Δ τ delayed data.The 1pps signal leading edge of delay compensation has been realized and having been synchronizeed with the reference 1pps signal leading edge of time transmission control end.
4, the time signal recompile of user's receiving terminal modulation
Due to compensation after time coding signal postponed 1s, the temporal information that user's receiving terminal obtains than the time transmit control end reference time information delay 1 second.At user's receiving terminal, the time information signal that the 1pps signal of compensation and demodulating and decoding device 2 are exported is given coding demodulator 2 simultaneously, recompile modulation, the time encoding information of recompile modulation 1 second in advance.The temporal information that has ensured user side is synchronizeed with the temporal information that sends control end.Coding demodulator 2 can offer user time B coded signal, 1pps signal, 100MHz frequency signal, 10MHz frequency signal, 5MHz frequency signal, radiofrequency signal simultaneously.The time tranfer of next stage can be adopted and be used the same method.Can carry out easily cascade.And ensure remote accurate synchronization of transmission time.
The present invention adopts and uses the same method the time tranfer of next stage, can carry out easily cascade, and ensures remote accurate synchronization of transmission time.The present invention, compared with existing pre-compensating method, according to different stage, does not need different temporal information leads is set, and does not need the pre-compensation means of different stage, moves easy.The present invention has the simple, practical and reliable property of method advantages of higher, can in optical fiber time transmission transmission, promote the use of.
Brief description of the drawings
Fig. 1 is the flow chart of the embodiment of the present invention 1.
Fig. 2 is that optical fiber time transmits pre-compensating and post-equalization transmission time signal sequence schematic diagram of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in more detail, but the invention is not restricted to these embodiment.
Embodiment 1
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
1, the measuring optical fiber time is transmitted closed loop transmission delay Δ T
Referring to Fig. 1,2, in Fig. 2, sequential A sends the time coding signal of control end the time, comprises 1pps signal, when time information signal, minute, second, and propagation time delay data Δ τ; Sequential B be user's receiving terminal receive do not carry out time delay equalization time coding signal; Sequential C is the time coding signal of the employing pre-compensating method that receives of user's receiving terminal; Sequential D is after the employing post-equalization of user's receiving terminal output and the time coding signal of recompile.
Transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1550nm, and the light signal that wavelength X 1 is 1550nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1550nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1550nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1551nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1551nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1550nm and wavelength X 2 are 1551nm adopts wavelength to be less than 1nm is transmitted, and has improved precision, has reduced the asymmetry of transmission delay.Transmit control end in the time, the light signal that wavelength X 2 is 1551nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
2, calculate optical fiber time and transmit one-way transmission delay Δ τ
Referring to Fig. 1, transmit control end in the time, the fibre-optical closed-loop transmission delay data Δ T of time-interval counter output is to coding demodulator 1, and the equipment that closed loop transmission delayed data Δ T includes time transmission control end postpones Δ t
tpostpone Δ t with the equipment of user's receiving terminal
r, this equipment is calibrated mensuration before postponing to transmit transmission in the time.Owing to adopting dense wavelength division multiplexing method, think that the transmission delay of two wavelength is identical.Coding demodulator 1 calculates by following formula:
In formula, Δ τ is that one-way transmission postpones, Δ t
tthat the equipment that transmits control end the time postpones, Δ t
rthe equipment that is user's receiving terminal postpones, and Δ T is that closed loop transmission postpones.When receiving time-interval counter, coding demodulator 1 sends here after Δ T data, show that as calculated transmitting control end from the time postpones Δ τ to the one-way transmission of user's receiving terminal, one-way transmission postpones Δ τ and carry out coded modulation by coding demodulator 1 together with reference time signal, 1pps signal, and is sent to user's receiving terminal.
3, optical fiber time transmits the post-equalization of 1pps
Referring to Fig. 1, at user's receiving terminal, the radiofrequency signal that optical-electrical converter 2 is exported is given demodulating and decoding device 2, first demodulating and decoding device 2 demodulates time coding signal from radiofrequency signal, time coding signal is as shown in sequential B, and demodulating and decoding device 2 is exported 1pps signal, time information signal, one-way transmission delay Δ τ.Delay compensator receives 1pps signal and one-way transmission postpones, after Δ τ, to compensate receiving 1pps signal.So-called compensation, is actually the 1pps signal leading edge receiving is postponed to 1s-Δ τ delayed data.Time encoding after compensation is as shown in sequential C, sequential D.The 1pps signal leading edge of delay compensation is transmitted control end with the time and has been realized and having synchronizeed with reference to 1pps signal leading edge.
4, the recompile of user's destination time signal modulation
Referring to Fig. 2, the time is transmitted the time encoding of control end as shown in sequential A, temporal information be 9 hours 35 points 47 seconds, the temporal information that user's receiving terminal demodulating and decoding device 2 obtains as shown in sequential B, temporal information be still 9 hours 35 points 47 seconds.Elapsed time transmits after control end pre-compensating, time encoding is as shown in sequential C, temporal information be still 9 hours 35 points 47 seconds, align with the forward position of the 1pps signal of sequential A in the forward position of the 1pps signal after compensation, but at this moment the temporal information of sequential A be 9 hours 35 points 48 seconds, the temporal information after pre-compensating is transmitted the temporal information of control end than the time and has been lagged behind 1 second.Therefore,, at user's receiving terminal, the time information signal that the 1pps signal of compensation and demodulating and decoding device 2 are exported is given coding demodulator 2 simultaneously, recompile modulation, the temporal information of modulation 1 second in advance, its time encoding as shown in sequential D, temporal information be adjusted into 9 hours 35 points 48 seconds.The temporal information that like this, has just ensured user side is synchronizeed with the reference time information that sends control end.Coding demodulator 2 can offer user time B coded signal, 1pps signal, 100MHz frequency signal, 10MHz frequency signal, 5MHz frequency signal, radiofrequency signal simultaneously.The time tranfer of next stage can be adopted and be used the same method.Can carry out easily cascade.And ensure remote accurate synchronization of transmission time.
Embodiment 2
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
Transmitting closed loop transmission in the measuring optical fiber time postpones in Δ T step 1, transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1570nm, the light signal that wavelength X 1 is 1570nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1570nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1570nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1571nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1571nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1570nm and wavelength X 2 are 1571nm adopts wavelength to be less than 1nm is transmitted.Transmit control end in the time, the light signal that wavelength X 2 is 1571nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
Other step is identical with embodiment 1.
Embodiment 3
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
Transmitting closed loop transmission in the measuring optical fiber time postpones in Δ T step 1, transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1590nm, the light signal that wavelength X 1 is 1590nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1590nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1590nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1591nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1591nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1590nm and wavelength X 2 are 1591nm adopts wavelength to be less than 1nm is transmitted.Transmit control end in the time, the light signal that wavelength X 2 is 1591nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
Other step is identical with embodiment 1.
Embodiment 4
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
Transmitting closed loop transmission in the measuring optical fiber time postpones in Δ T step 1, transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1330nm, the light signal that wavelength X 1 is 1330nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1330nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1330nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1331nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1331nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1330nm and wavelength X 2 are 1331nm adopts wavelength to be less than 1nm is transmitted.Transmit control end in the time, the light signal that wavelength X 2 is 1331nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
Other step is identical with embodiment 1.
Embodiment 5
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
Transmitting closed loop transmission in the measuring optical fiber time postpones in Δ T step 1, transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1350nm, the light signal that wavelength X 1 is 1350nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1350nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1350nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1351nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1351nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1350nm and wavelength X 2 are 1351nm adopts wavelength to be less than 1nm is transmitted.Transmit control end in the time, the light signal that wavelength X 2 is 1351nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
Other step is identical with embodiment 1.
Embodiment 6
Taking 9 hours 35 points of 47 second reference time signals from atomic clock as example, illustrate that the post-equalization method of optical fiber time transmission propagation time delay is as follows.
Transmitting closed loop transmission in the measuring optical fiber time postpones in Δ T step 1, transmit control end in the time, 9 hours 35 points of 47 second reference times that atomic clock is come, give coding demodulator 1, coding demodulator 1 first carries out time encoding according to sequential A, be modulated into radiofrequency signal output, radiofrequency signal is given laser 1 and is modulated into the light signal that wavelength X 1 is 1390nm, the light signal that wavelength X 1 is 1390nm is fed to wavelength division multiplexer 1, the light signal feed-in optical fiber that wavelength division multiplexer 1 is 1390nm by wavelength X 1, arrives user's receiving terminal through Optical Fiber Transmission.At user's receiving terminal, the light signal that the wavelength X 1 that Optical Fiber Transmission is come is 1390nm, through wavelength division multiplexer 2, outputs to optical-electrical converter 2, and optical-electrical converter 2 converts light signal to radiofrequency signal and outputs to laser 2 and demodulating and decoding device 2 simultaneously.The light signal that the wavelength X 2 that laser 2 is exported is 1391nm, then by wavelength division multiplexer 2 input optical fibres, optical fiber transmits control end by wavelength X 2 for the optical return signal of 1391nm passes to the time.In order to improve precision, reduce the asymmetry of transmission delay, the dense wavelength division multiplexing method that the light signal that the light signal that wavelength X 1 is 1390nm and wavelength X 2 are 1391nm adopts wavelength to be less than 1nm is transmitted.Transmit control end in the time, the light signal that wavelength X 2 is 1391nm, through wavelength division multiplexer 1, is given optical-electrical converter 1.Optical-electrical converter 1 converts light signal to radiofrequency signal and outputs to demodulating and decoding device 1, and demodulating and decoding device 1 demodulates 1pps signal from radiofrequency signal, is the 1pps signal of fibre-optical closed-loop passback.1pps signal with reference to 1pps signal and passback is given time-interval counter 1 simultaneously, carries out time difference measurement, time-interval counter output closed-loop transmission delay Δ T.
Other step is identical with embodiment 1.
Claims (2)
1. optical fiber time transmits a post-equalization method for propagation time delay, it is characterized in that it is made up of following step:
(1) the measuring optical fiber time is transmitted Bidirectional closed-loop transmission delay Δ T
Transmit control end in the time, reference time signal and 1pps signal that atomic clock is come, encoded modulators modulate becomes radiofrequency signal, radiofrequency signal is that λ 1 laser 1 is modulated into light signal through wavelength, wavelength be the light signal of λ 1 through wavelength division multiplexer 1 feed-in optical fiber, through Optical Fiber Transmission to user's receiving terminal; At user's receiving terminal, wavelength be the light signal of λ 1 through wavelength division multiplexer 2, then be demodulated into radiofrequency signal through optical-electrical converter 2, the laser 2 that radiofrequency signal is λ 2 by wavelength is again modulated to light signal again; Wavelength is that the light signal of λ 1 and wavelength are that the dense wavelength division multiplexing method that the light signal of λ 2 adopts wavelength to be less than 1nm is transmitted; Wavelength is that the light signal of λ 2 transmits control end through wavelength division multiplexer 2 and the optical fiber time that passes back to again; Transmit control end in the time, the wavelength being returned by optical fiber and wavelength division multiplexer 1 is the light signal of λ 2, demodulates radiofrequency signal by optical-electrical converter 1, and radiofrequency signal demodulates the 1pps signal of fibre-optical closed-loop passback again through demodulating and decoding device 1; Give time-interval counter with reference to 1pps signal and passback 1pps signal simultaneously, carry out time difference measurement, time-interval counter output data are fibre-optical closed-loop transmission delay Δ T;
Above-mentioned wavelength is that the light signal of λ 1 and wavelength are that the wave-length coverage of the light signal of λ 2 is 1550nm or 1331nm universal optical fibre communication band;
(2) calculate optical fiber time and transmit one-way transmission delay
Transmit control end in the time, the fibre-optical closed-loop transmission delay data Δ T of time-interval counter output is to coding demodulator 1, and coding demodulator 1 calculates by following formula:
Must transmit control end from the time and postpone Δ τ to the one-way transmission of user's receiving terminal, in formula, Δ τ is that one-way transmission postpones, Δ t
tthat the equipment that transmits control end the time postpones, Δ t
rthe equipment that is user's receiving terminal postpones, and Δ T is that closed loop transmission postpones, Δ t
twith Δ t
rbefore transmitting in the time, calibrate mensuration, one-way transmission postpones Δ τ and reference time signal, 1pps signal carry out coded modulation by coding demodulator 1, and is sent to user's receiving terminal;
(3) time is transmitted the post-equalization of 1pps
At user's receiving terminal, the radiofrequency signal that optical-electrical converter 2 is exported is given demodulating and decoding device 2, demodulating and decoding device 2 carries out demodulating and decoding output 1pps signal, time information signal, one-way transmission delay Δ τ to delay compensator, delay compensator compensates 1pps signal, synchronizes with the 1pps signal leading edge that the time is transmitted control end reference in the 1pps signal leading edge of delay compensation;
(4) recompile of user's destination time signal modulation
At user's receiving terminal, the time information signal that the 1pps signal of compensation and demodulating and decoding device 2 are exported is given coding demodulator 2 simultaneously, recompile modulation, the time encoding information of modulation 1 second in advance, coding demodulator 2 offers user time B coded signal, 1pps signal, 100MHz frequency signal, 10MHz frequency signal, 5MHz frequency signal, radiofrequency signal simultaneously, and the time tranfer of next stage is adopted and used the same method.
2. transmit the post-equalization method of propagation time delay according to optical fiber time claimed in claim 1, it is characterized in that: transmit in the post-equalization step (3) of 1pps at optical fiber time, described delay compensator compensates as delay compensator is by 1 second-Δ of the 1pps signal leading edge delay τ delayed data receiving 1pps signal.
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