CN111698053A - Optical fiber time frequency transmission system and method using Manchester coding - Google Patents
Optical fiber time frequency transmission system and method using Manchester coding Download PDFInfo
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- CN111698053A CN111698053A CN202010549733.6A CN202010549733A CN111698053A CN 111698053 A CN111698053 A CN 111698053A CN 202010549733 A CN202010549733 A CN 202010549733A CN 111698053 A CN111698053 A CN 111698053A
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Abstract
The invention discloses an optical fiber time frequency transmission system and method using Manchester coding, wherein the system comprises: a transmitting end; the transmitting end includes: the device comprises a time frequency source, an N frequency multiplier, a first TDC, a first encoder, a first laser, a first circulator, a first photodetector and a first decoder. The invention combines the optical fiber time frequency transmission technology with high precision and high stability with the Manchester coding mode which contains self-timing information, is easy to extract frequency signals from data, is easy to encode/decode and has high anti-interference capability, and can realize the synchronous transmission of time, frequency and data with high precision and high reliability on the optical fiber.
Description
Technical Field
The invention belongs to the technical field of time frequency information, and particularly relates to an optical fiber time frequency transmission system and method utilizing Manchester coding.
Background
The optical fiber time frequency transmission technology has become one of the key supporting technologies in the fields of aerospace, high-speed communication, geodetic surveying, precision metering, deep space exploration, gravitational wave exploration and the like due to the advantages of safety, reliability and stability. The optical fiber time frequency transmission technology not only has high precision and high stability, but also has the advantages of rich communication resources and stronger communication capability due to the fact that the ground optical fiber is used as a bearing network. With the social progress and the improvement of living standard, people not only can meet the high-precision transmission of time frequency, but also can put higher requirements on data capacity and communication instantaneity in the communication process; the existing optical fiber time frequency transmission can only transmit time signals, and the simultaneous transmission of high-capacity data and time frequency signals is difficult to realize.
In summary, a new system and method for fiber time frequency transmission using manchester encoding is needed.
Disclosure of Invention
The present invention is directed to a system and method for fiber time frequency transmission using manchester coding to solve one or more of the above-mentioned problems. The invention can realize the synchronous transmission of time, frequency and data on the optical fiber.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to an optical fiber time frequency transmission system using Manchester coding, which comprises: a transmitting end;
the transmitting end includes:
a time frequency source for transmitting a time signal and a frequency signal;
the N frequency multiplier is used for receiving the frequency signal sent by the time frequency source, amplifying and outputting the frequency signal;
the first TDC is used for receiving a time signal sent by a time frequency source and a returned time signal and outputting comparison data of a transmitting end;
the first encoder is used for receiving network data of a transmitting end, frequency signals amplified and output by the N frequency multiplier, time signals sent by a time frequency source and transmitting end comparison data output by the first TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
the first laser is used for receiving the coding signal sent by the first coder and outputting laser;
the first circulator is used for receiving the laser output by the first laser and outputting the laser to the receiving end through the optical fiber link; the laser is used for receiving and outputting the laser output by the receiving end;
the first photoelectric detector is used for receiving the receiving end laser output by the first circulator, converting the receiving end laser into an electric signal and outputting a coding signal of the receiving end;
and the first decoder is used for receiving the coded signal of the receiving end output by the first photoelectric detector and outputting a returned time signal and network data of the receiving end.
The invention relates to an optical fiber time frequency transmission system using Manchester coding, which comprises: a receiving end;
the receiving end includes:
the second circulator is used for receiving the laser output by the second laser and outputting the laser to the transmitting end through the optical fiber link; the laser is used for receiving and outputting the laser output by the transmitting end;
the second photoelectric detector is used for receiving the transmitting end laser output by the second circulator, converting the transmitting end laser into an electric signal and outputting a coded signal of the transmitting end;
the second decoder is used for receiving the coded signal of the transmitting end output by the second photoelectric detector, and outputting the received time signal, the received frequency signal, the network data of the transmitting end and the comparison data of the transmitting end;
the digital phase-locked loop circuit is used for receiving the frequency signal demodulated by the second decoder and outputting a receiving end synchronous frequency signal;
the time generation module is used for receiving the receiving end synchronous frequency signal output by the digital phase-locked loop circuit and outputting a receiving end regeneration time signal;
the programmable delayer is used for receiving the receiving end regeneration time signal output by the time generation module, performing time delay adjustment and outputting a receiving end synchronization time signal;
the second TDC is used for receiving the received time signal output by the second decoder and the receiving end synchronous time signal output by the programmable delayer and outputting receiving end comparison data;
the operation control unit is used for receiving the comparison data of the transmitting end and the comparison data of the receiving end, performing delay amount operation and controlling the programmable delayer to perform delay adjustment on the regeneration time signal of the receiving end;
the second encoder is used for receiving end network data, frequency signals output by the digital phase-locked loop circuit, returned time signals output by the operation control unit and receiving end comparison data output by the second TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
and the second laser is used for receiving the coding signal sent by the second coder and outputting laser.
The invention relates to an optical fiber time frequency transmission system using Manchester coding, which comprises: a transmitting end and a receiving end; the transmitting end and the receiving end carry out data transmission through an optical fiber link;
the transmitting end includes:
a time frequency source for transmitting a time signal and a frequency signal;
the N frequency multiplier is used for receiving the frequency signal sent by the time frequency source, amplifying and outputting the frequency signal;
the first TDC is used for receiving a time signal sent by a time frequency source and a returned time signal and outputting comparison data of a transmitting end;
the first encoder is used for receiving network data of a transmitting end, frequency signals amplified and output by the N frequency multiplier, time signals sent by a time frequency source and transmitting end comparison data output by the first TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
the first laser is used for receiving the coding signal sent by the first coder and outputting laser;
the first circulator is used for receiving the laser output by the first laser and outputting the laser to the receiving end through the optical fiber link; the laser receiving and outputting device is used for receiving and outputting laser output by the receiving end through the optical fiber link;
the first photoelectric detector is used for receiving the receiving end laser output by the first circulator, converting the receiving end laser into an electric signal and outputting a coding signal of the receiving end;
and the first decoder is used for receiving the coded signal of the receiving end output by the first photoelectric detector and outputting a returned time signal and network data of the receiving end.
A further improvement of the present invention is that the receiving end comprises:
the second circulator is used for receiving the laser output by the second laser and outputting the laser to the transmitting end through the optical fiber link; the laser is used for receiving and outputting the laser output by the transmitting end;
the second photoelectric detector is used for receiving the transmitting end laser output by the second circulator, converting the transmitting end laser into an electric signal and outputting a coded signal of the transmitting end;
the second decoder is used for receiving the coded signal of the transmitting end output by the second photoelectric detector, and outputting the received time signal, the received frequency signal, the network data of the transmitting end and the comparison data of the transmitting end;
the digital phase-locked loop circuit is used for receiving the frequency signal demodulated by the second decoder and outputting a receiving end synchronous frequency signal;
the time generation module is used for receiving the receiving end synchronous frequency signal output by the digital phase-locked loop circuit and outputting a receiving end regeneration time signal;
the programmable delayer is used for receiving the receiving end regeneration time signal output by the time generation module, performing time delay adjustment and outputting a receiving end synchronization time signal;
the second TDC is used for receiving the received time signal output by the second decoder and the receiving end synchronous time signal output by the programmable delayer and outputting receiving end comparison data;
the operation control unit is used for receiving the comparison data of the transmitting end and the comparison data of the receiving end, performing delay amount operation and controlling the programmable delayer to perform delay adjustment on the regeneration time signal of the receiving end;
the second encoder is used for receiving end network data, frequency signals output by the digital phase-locked loop circuit, returned time signals output by the operation control unit and receiving end comparison data output by the second TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
and the second laser is used for receiving the coding signal sent by the second coder and outputting laser.
The invention is further improved in that the Manchester code decoding and frequency and time signal recovery process comprises the following steps:
1) detecting the rising edge and the falling edge of a code element in the coded signal, and converting all the rising edges and the falling edges into the rising edges to obtain a Data-Turn signal;
2) sampling a Data-Turn signal by using a local oscillator in a digital phase-locked loop circuit, recovering a frequency signal, and realizing the synchronization of the frequency signal;
3) analyzing the codes by using the frequency signals recovered in the step 2) to obtain network data and transmitting end comparison data;
4) in the decoding process of step 3), the frame header of each frame data is output as a time signal to realize the reply of the time signal.
A further improvement of the present invention is that, in step 1), the step of converting all rising edges and falling edges into rising edges includes: and inputting the coded signal Data into an exclusive-OR gate, inputting the other path of Data into an exclusive-OR gate after passing through a delay, and converting all rising edges and falling edges into rising edges through the exclusive-OR gate to obtain a Data-Turn signal.
The invention further improves that in step 2), the PFD in the digital phase-locked loop circuit comprises: a first edge D flip-flop and a second edge D flip-flop;
clock CLK of first edge D flip-flop1Accessing a frequency division 2 signal of a local oscillator, wherein a D end is connected with Vcc, a high level is set, and a Q end outputs an UP signal which is used as an input signal of an LPF;
clock CLK of second edge D flip-flop2And a Data-Pulse signal is accessed, a D end is connected with an UP signal output by a Q end of the first edge D trigger, and the Q end outputs a zero clearing signal which is used for simultaneously controlling the first edge D trigger and the CLR end of the second edge D trigger.
The invention relates to an optical fiber time frequency transmission method by using Manchester coding, which comprises the following steps:
step 2, inputting the network data of the transmitting terminal into a first encoder;
step 3, inputting the frequency signal output by the time frequency source into an N frequency multiplier, and inputting the frequency signal output by the N frequency multiplier into a first encoder;
step 4, inputting the coded signal from the receiving end into a first decoder to perform decoding of Manchester codes and frequency and time signal recovery, and obtaining network data, frequency signals and returned time signals of the receiving end; inputting the obtained time signal returned by the receiving end and the time signal output by the time frequency source into a first TDC for time interval measurement to obtain comparison data of the transmitting end;
step 5, inputting the transmitting end comparison data obtained in the step 4 into a first encoder, obtaining a coding signal containing time, frequency and data information by using a Manchester coding mode, enabling the coding signal to modulate a first laser to output laser, enabling the laser to pass through a first circulator, transmitting one path of the laser to a receiving end through an optical fiber link, and inputting the other path of the laser to a first photoelectric detector;
step 6, inputting the laser transmitted to the receiving end in the step 5 to a second photoelectric detector through a second circulator to be converted into an electric signal, and obtaining a coded signal of the transmitting end;
step 7, inputting the coded signal of the transmitting end obtained in the step 6 into a second decoder for decoding of a Manchester code and recovering of frequency and time signals, so as to obtain network data, comparison data, frequency signals and received time signals of the transmitting end;
step 8, the frequency signal decoded and recovered in the step 7 passes through a time generation module and a programmable delay module to obtain a local time signal of a receiving end;
step 9, inputting the time signal of the transmitting end received in the step 7 and the local time signal of the receiving end obtained in the step 8 into a second TDC for time interval measurement to obtain comparison data of the receiving end;
step 10, inputting the receiving end comparison data obtained in the step 9 and the transmitting end comparison data obtained in the step 7 into an operation control unit together to obtain a delay increment delta T required to be adjusted;
and 11, performing delay control on the local time signal of the receiving end obtained in the step 8 through a programmable delayer, wherein the delay control quantity is delta T, and realizing the stable synchronization of the time signal receiving end and the transmitting end.
The invention is further improved in that the Manchester code decoding and frequency and time signal recovery process comprises the following steps:
1) detecting the rising edge and the falling edge of a code element in the coded signal, and converting all the rising edges and the falling edges into the rising edges to obtain a Data-Turn signal;
2) sampling a Data-Turn signal by using a local oscillator in a digital phase-locked loop circuit, recovering a frequency signal, and realizing the synchronization of the frequency signal;
3) analyzing the codes by using the frequency signals recovered in the step 2) to obtain network data and transmitting end comparison data;
4) in the decoding process of step 3), the frame header of each frame data is output as a time signal to realize the reply of the time signal.
A further improvement of the present invention is that, in step 1), the step of converting all rising edges and falling edges into rising edges includes: and inputting the coded signal Data into an exclusive-OR gate, inputting the other path of Data into an exclusive-OR gate after passing through a delay, and converting all rising edges and falling edges into rising edges through the exclusive-OR gate to obtain a Data-Turn signal.
Compared with the prior art, the invention has the following beneficial effects:
the system combines the optical fiber time frequency transmission technology with high precision and high stability with the Manchester coding mode which has the advantages of self-timing information, easy extraction of frequency signals from data, easy coding/decoding and high anti-interference capability, and can realize the synchronous transmission of time, frequency and data with high precision and high reliability on the optical fiber.
The method of the invention combines the advantages of Manchester coding mode including easy self-timing information extraction of frequency signals from data, easy coding/decoding and high anti-interference capability on the basis of high-precision and high-stability transmission of optical fiber time frequency, extracts rising/falling edges in code elements as clocks, and converts all rising/falling edges into rising edges, so that the period of the clocks is stable, the simultaneous transmission of time frequency and large-capacity data is realized, the coding/decoding steps are simplified, and the synchronous transmission of high-precision, high-precision and high-reliability optical fiber time frequency data is ensured.
In the invention, the transmitted time signal 1PPS is as follows: the accuracy can reach 10ps, and the stability can reach 1ps @1000 s. The frequency stability of the transmitted frequency signal of 100MHz can reach 1E-13/s. The transmission rate of the transferred network data may be up to 50 Mbit/s.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic diagram of the general structure of an optical fiber time-frequency transfer system using Manchester encoding according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a Manchester code frequency pulse recovery timing sequence according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of transition pulse extraction logic according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a high-stability recovered frequency signal in an embodiment of the present invention.
Detailed Description
In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.
Referring to fig. 1, an optical fiber time-frequency transmission system using manchester encoding according to an embodiment of the present invention includes: the transmitting end and the receiving end carry out data transmission through an optical fiber link; the receiving end comprises a second circulator, a second photodetector, a second laser, a second decoder, a PLL (Phase Locked Loop), a Time generation module, a second TDC, a second encoder, an operation control unit and a programmable delayer; FIG. 2 is a timing diagram for Manchester code frequency pulse recovery of an embodiment; FIG. 3 is a transition pulse extraction logic diagram of an embodiment; fig. 4 is a schematic diagram of a high-stability recovery frequency signal according to an embodiment, and as can be seen from fig. 4, the PLL high-stability recovery frequency signal requires a PFD, an LPF, a PI, an LO local oscillator module, and a 2-fold frequency divider, which are formed by two D flip-flops.
In the embodiment of the invention, the reference frequency signal output by the time frequency source is 100MHz, and the reference time signal output by the time frequency source is 1PPS signal. The frequency signal in the embodiment of the present invention is 100MHz, the period corresponding to the symbol signal in fig. 2 is T ═ 10ns, and the frequency signal corresponds to the Data signal and the Data-Turn signal in fig. 3 and the Data-Pulse signal in fig. 4.
In the embodiment of the invention, an LO module outputs a pulse signal with a period of T/2, and the pulse signal is used as a clock CLK of a first edge D trigger after being subjected to frequency division by 21The Data-Turn signal is used as the clock CLK of the second edge D flip-flop2Q of the first D flip-flop1D for controlling second D trigger2The output of the second edge D trigger is used as zero clearing signal to two D triggers simultaneouslyIs cleared, then at Q1And the terminal obtains a phase discrimination signal. The phase detection signal is filtered by an LPF (low pass filter), and is adjusted by a PI (proportional integrator), and a high-stability frequency signal is output by an LO (local oscillator) module.
The optical fiber time frequency transmission method utilizing Manchester coding in the embodiment of the invention specifically comprises the following steps:
step 2, inputting the network data of the transmitting terminal into a first encoder;
step 3, the time frequency source outputs 100MHz frequency signals, the 100MHz frequency signals are processed by an N frequency multiplier, and the N multiplied by 100MHz frequency signals are input into a first encoder;
step 4, decoding and frequency and time signal recovery of Manchester codes are carried out on the coded signals from the receiving end through a first decoder, network data, 100MHz frequency signals and 1PPS time signals of the receiving end are respectively obtained, the obtained 1PPS time signals and the 1PPS time signals output by the time frequency source are input into a TDC1 (time interval measurer) together for time interval measurement, and comparison data of the transmitting end are obtained;
step 5, the transmitting end compares the Data and inputs the Data into a first encoder, and obtains a coded signal (with code element as unit, Data coded signal is periodic, and the period is T) containing time frequency and Data information by using a Manchester coding mode, so that the coded signal modulates a first laser to output laser, the laser passes through a first circulator, one path is transmitted to a receiving end through an optical fiber link, and the other path is input into a first photoelectric detector;
step 6, inputting the laser transmitted to the receiving end in the step 5 into a second photoelectric detector through a second circulator to be converted into an electric signal, and obtaining a coded signal;
step 7, inputting the coded signal obtained in the step 6 into a second decoder to perform decoding of Manchester codes and frequency and time signal recovery, and respectively obtaining network data, comparison data, a 100MHz frequency signal and a received 1PPS time signal of a transmitting end;
and 8, generating a local 1PPS time signal of the receiving end by the 100MHz frequency signal decoded and recovered in the step 7 through a time generation module and a programmable delay module.
Step 9, inputting the received 1PPS time signal in step 7 and the local 1PPS time signal of the receiving end in step 8 into a second TDC (time interval measurer) to perform time interval measurement, so as to obtain comparison data of the receiving end;
step 10, inputting the receiving end comparison data in the step 9 and the transmitting end comparison data obtained in the step 7 into an operation control unit together, and calculating to obtain a delay increment delta T to be adjusted;
step 11, a programmable delayer carries out delay control on the local time signal of the receiving end in the step 8, wherein the delay control quantity is delta T;
therefore, high stable synchronization of the 1PPS time signal receiving end and the transmitting end is realized, and the synchronization precision reaches ps magnitude.
In the embodiment of the invention, the decoding and frequency and time signal recovery process of the Manchester code mainly comprises the following steps:
1) and detecting the rising edge and the falling edge of the code element in the coded signal, and converting all the rising edges and the falling edges into the rising edges to obtain a Data-Turn signal.
In the embodiment of the invention, the method for converting all rising edges and falling edges into the rising edges is that the coded signal is directly input into the exclusive-or gate, the other path of the coded signal is input into the exclusive-or gate after passing through a delay, and then the rising edges and the falling edges are converted into the rising edges by the exclusive-or gate.
2) Sampling a Data-Turn signal by using a local oscillator LO to recover a 100MHz frequency signal;
the recovered 100MHz frequency signal is further explained.
Passing the Data-Turn signal through a PFD (frequency phase detector), wherein the PFD is composed of two edge D triggers, and an LO module outputs a pulse signal with a period of T/2, and the pulse signal is used as the clock CLK of the first edge D trigger after being frequency-divided by 21The Data-Turn signal is used as the clock CLK of the second edge D flip-flop2To make the first oneQ of D flip-flop1D for controlling second D trigger2The output of the second edge D trigger is used as a zero clearing signal to clear the two D triggers simultaneously, and then Q is obtained1And the terminal obtains a phase discrimination signal. The phase discrimination signal is filtered by an LPF (low pass filter), is adjusted by a PI (proportional integrator), and outputs a 100MHz frequency signal with high stability through an LO (local oscillator) module;
thus, high stability synchronization of 100MHz frequency signals is realized, and the stability reaches E-16/day;
3) analyzing the codes by using the recovered frequency signals to obtain network data and transmitting end comparison data;
4) and 3) outputting the frame head of each frame data as a time signal in the decoding process, thereby recovering the 1PPS time signal.
On the basis of the transmission of optical fiber time frequency with high precision and high stability, the invention combines the advantages of Manchester coding mode including easy extraction of frequency signals from data by self-timing information, easy coding/decoding and high anti-interference capability, extracts rising/falling edges in code elements as clocks, and converts all rising/falling edges into rising edges, so that the period of the clocks is stable, the simultaneous transmission of time frequency and large-capacity data is realized, the coding/decoding steps are simplified, and the synchronous transmission of optical fiber time frequency data with high precision, high precision and high reliability is ensured.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.
Claims (10)
1. An optical fiber time-frequency transfer system using manchester encoding, comprising: a transmitting end;
the transmitting end includes:
a time frequency source for transmitting a time signal and a frequency signal;
the N frequency multiplier is used for receiving the frequency signal sent by the time frequency source, amplifying and outputting the frequency signal;
the first TDC is used for receiving a time signal sent by a time frequency source and a returned time signal and outputting comparison data of a transmitting end;
the first encoder is used for receiving network data of a transmitting end, frequency signals amplified and output by the N frequency multiplier, time signals sent by a time frequency source and transmitting end comparison data output by the first TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
the first laser is used for receiving the coding signal sent by the first coder and outputting laser;
the first circulator is used for receiving the laser output by the first laser and outputting the laser to the receiving end through the optical fiber link; the laser is used for receiving and outputting the laser output by the receiving end;
the first photoelectric detector is used for receiving the receiving end laser output by the first circulator, converting the receiving end laser into an electric signal and outputting a coding signal of the receiving end;
and the first decoder is used for receiving the coded signal of the receiving end output by the first photoelectric detector and outputting a returned time signal and network data of the receiving end.
2. An optical fiber time-frequency transfer system using manchester encoding, comprising: a receiving end;
the receiving end includes:
the second circulator is used for receiving the laser output by the second laser and outputting the laser to the transmitting end through the optical fiber link; the laser is used for receiving and outputting the laser output by the transmitting end;
the second photoelectric detector is used for receiving the transmitting end laser output by the second circulator, converting the transmitting end laser into an electric signal and outputting a coded signal of the transmitting end;
the second decoder is used for receiving the coded signal of the transmitting end output by the second photoelectric detector, and outputting the received time signal, the received frequency signal, the network data of the transmitting end and the comparison data of the transmitting end;
the digital phase-locked loop circuit is used for receiving the frequency signal demodulated by the second decoder and outputting a receiving end synchronous frequency signal;
the time generation module is used for receiving the receiving end synchronous frequency signal output by the digital phase-locked loop circuit and outputting a receiving end regeneration time signal;
the programmable delayer is used for receiving the receiving end regeneration time signal output by the time generation module, performing time delay adjustment and outputting a receiving end synchronization time signal;
the second TDC is used for receiving the received time signal output by the second decoder and the receiving end synchronous time signal output by the programmable delayer and outputting receiving end comparison data;
the operation control unit is used for receiving the comparison data of the transmitting end and the comparison data of the receiving end, performing delay amount operation and controlling the programmable delayer to perform delay adjustment on the regeneration time signal of the receiving end;
the second encoder is used for receiving end network data, frequency signals output by the digital phase-locked loop circuit, returned time signals output by the operation control unit and receiving end comparison data output by the second TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
and the second laser is used for receiving the coding signal sent by the second coder and outputting laser.
3. An optical fiber time-frequency transfer system using manchester encoding, comprising: a transmitting end and a receiving end; the transmitting end and the receiving end carry out data transmission through an optical fiber link;
the transmitting end includes:
a time frequency source for transmitting a time signal and a frequency signal;
the N frequency multiplier is used for receiving the frequency signal sent by the time frequency source, amplifying and outputting the frequency signal;
the first TDC is used for receiving a time signal sent by a time frequency source and a returned time signal and outputting comparison data of a transmitting end;
the first encoder is used for receiving network data of a transmitting end, frequency signals amplified and output by the N frequency multiplier, time signals sent by a time frequency source and transmitting end comparison data output by the first TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
the first laser is used for receiving the coding signal sent by the first coder and outputting laser;
the first circulator is used for receiving the laser output by the first laser and outputting the laser to the receiving end through the optical fiber link; the laser receiving and outputting device is used for receiving and outputting laser output by the receiving end through the optical fiber link;
the first photoelectric detector is used for receiving the receiving end laser output by the first circulator, converting the receiving end laser into an electric signal and outputting a coding signal of the receiving end;
and the first decoder is used for receiving the coded signal of the receiving end output by the first photoelectric detector and outputting a returned time signal and network data of the receiving end.
4. The system of claim 3, wherein the receiving end comprises:
the second circulator is used for receiving the laser output by the second laser and outputting the laser to the transmitting end through the optical fiber link; the laser is used for receiving and outputting the laser output by the transmitting end;
the second photoelectric detector is used for receiving the transmitting end laser output by the second circulator, converting the transmitting end laser into an electric signal and outputting a coded signal of the transmitting end;
the second decoder is used for receiving the coded signal of the transmitting end output by the second photoelectric detector, and outputting the received time signal, the received frequency signal, the network data of the transmitting end and the comparison data of the transmitting end;
the digital phase-locked loop circuit is used for receiving the frequency signal demodulated by the second decoder and outputting a receiving end synchronous frequency signal;
the time generation module is used for receiving the receiving end synchronous frequency signal output by the digital phase-locked loop circuit and outputting a receiving end regeneration time signal;
the programmable delayer is used for receiving the receiving end regeneration time signal output by the time generation module, performing time delay adjustment and outputting a receiving end synchronization time signal;
the second TDC is used for receiving the received time signal output by the second decoder and the receiving end synchronous time signal output by the programmable delayer and outputting receiving end comparison data;
the operation control unit is used for receiving the comparison data of the transmitting end and the comparison data of the receiving end, performing delay amount operation and controlling the programmable delayer to perform delay adjustment on the regeneration time signal of the receiving end;
the second encoder is used for receiving end network data, frequency signals output by the digital phase-locked loop circuit, returned time signals output by the operation control unit and receiving end comparison data output by the second TDC and outputting encoding signals containing time, frequency and data information obtained by a Manchester encoding mode;
and the second laser is used for receiving the coding signal sent by the second coder and outputting laser.
5. The system of claim 3, wherein the Manchester code decoding and frequency and time signal recovery process comprises:
1) detecting the rising edge and the falling edge of a code element in the coded signal, and converting all the rising edges and the falling edges into the rising edges to obtain a Data-Turn signal;
2) sampling a Data-Turn signal by using a local oscillator in a digital phase-locked loop circuit, recovering a frequency signal, and realizing the synchronization of the frequency signal;
3) analyzing the codes by using the frequency signals recovered in the step 2) to obtain network data and transmitting end comparison data;
4) in the decoding process of step 3), the frame header of each frame data is output as a time signal to realize the reply of the time signal.
6. The system as claimed in claim 5, wherein the step of converting all rising and falling edges into rising edges in step 1) comprises: and inputting the coded signal Data into an exclusive-OR gate, inputting the other path of Data into an exclusive-OR gate after passing through a delay, and converting all rising edges and falling edges into rising edges through the exclusive-OR gate to obtain a Data-Turn signal.
7. The system of claim 5, wherein in step 2), the PFD in the digital phase-locked loop circuit comprises: a first edge D flip-flop and a second edge D flip-flop;
clock CLK of first edge D flip-flop1Accessing a frequency division 2 signal of a local oscillator, wherein a D end is connected with Vcc, a high level is set, and a Q end outputs an UP signal which is used as an input signal of an LPF;
clock CLK of second edge D flip-flop2And a Data-Pulse signal is accessed, a D end is connected with an UP signal output by a Q end of the first edge D trigger, and the Q end outputs a zero clearing signal which is used for simultaneously controlling the first edge D trigger and the CLR end of the second edge D trigger.
8. An optical fiber time frequency transfer method using Manchester encoding, comprising the steps of:
step 1, outputting a path of time signal to a first encoder through a time frequency source;
step 2, inputting the network data of the transmitting terminal into a first encoder;
step 3, inputting the frequency signal output by the time frequency source into an N frequency multiplier, and inputting the frequency signal output by the N frequency multiplier into a first encoder;
step 4, inputting the coded signal from the receiving end into a first decoder to perform decoding of Manchester codes and frequency and time signal recovery, and obtaining network data, frequency signals and returned time signals of the receiving end; inputting the obtained time signal returned by the receiving end and the time signal output by the time frequency source into a first TDC for time interval measurement to obtain comparison data of the transmitting end;
step 5, inputting the transmitting end comparison data obtained in the step 4 into a first encoder, obtaining a coding signal containing time, frequency and data information by using a Manchester coding mode, enabling the coding signal to modulate a first laser to output laser, enabling the laser to pass through a first circulator, transmitting one path of the laser to a receiving end through an optical fiber link, and inputting the other path of the laser to a first photoelectric detector;
step 6, inputting the laser transmitted to the receiving end in the step 5 to a second photoelectric detector through a second circulator to be converted into an electric signal, and obtaining a coded signal of the transmitting end;
step 7, inputting the coded signal of the transmitting end obtained in the step 6 into a second decoder for decoding of a Manchester code and recovering of frequency and time signals, so as to obtain network data, comparison data, frequency signals and received time signals of the transmitting end;
step 8, the frequency signal decoded and recovered in the step 7 passes through a time generation module and a programmable delay module to obtain a local time signal of a receiving end;
step 9, inputting the time signal of the transmitting end received in the step 7 and the local time signal of the receiving end obtained in the step 8 into a second TDC for time interval measurement to obtain comparison data of the receiving end;
step 10, inputting the receiving end comparison data obtained in the step 9 and the transmitting end comparison data obtained in the step 7 into an operation control unit together to obtain a delay increment delta T required to be adjusted;
and 11, performing delay control on the local time signal of the receiving end obtained in the step 8 through a programmable delayer, wherein the delay control quantity is delta T, and realizing the stable synchronization of the time signal receiving end and the transmitting end.
9. The method for optical fiber time-frequency transfer using manchester encoding according to claim 8, wherein the decoding of manchester code and the frequency-time signal recovery process comprise:
1) detecting the rising edge and the falling edge of a code element in the coded signal, and converting all the rising edges and the falling edges into the rising edges to obtain a Data-Turn signal;
2) sampling a Data-Turn signal by using a local oscillator in a digital phase-locked loop circuit, recovering a frequency signal, and realizing the synchronization of the frequency signal;
3) analyzing the codes by using the frequency signals recovered in the step 2) to obtain network data and transmitting end comparison data;
4) in the decoding process of step 3), the frame header of each frame data is output as a time signal to realize the reply of the time signal.
10. The method as claimed in claim 9, wherein the step of converting all rising and falling edges into rising edges in step 1) comprises: and inputting the coded signal Data into an exclusive-OR gate, inputting the other path of Data into an exclusive-OR gate after passing through a delay, and converting all rising edges and falling edges into rising edges through the exclusive-OR gate to obtain a Data-Turn signal.
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