CN103812553B - High-precision optical fiber two-way Time transfer receiver equipment delay unsymmetry scaling method - Google Patents

Abstract

A kind of high-precision optical fiber two-way Time transfer receiver equipment delay unsymmetry scaling method, including step: 1. set up optical fiber bidirectional Time transfer receiver equipment delay calibration system；2. the reception chain-circuit time delay between optical fiber bidirectional Time transfer receiver equipment is calibrated poor；3. the reception chain-circuit time delay between optical fiber bidirectional Time transfer receiver equipment is calibrated poor；4. the time delay unsymmetry between optical fiber bidirectional Time transfer receiver equipment is calibrated.The present invention can not only calibrate the unsymmetry of time delay between optical fiber bidirectional Time transfer receiver equipment simply and easily, and time delay unsymmetry between any time-frequency equipment can be calibrated, effectively overcome the impact that time delay accuracy is brought by optical fiber or cable time delay difference.

Description

High-precision calibration method for time delay asymmetry of optical fiber bidirectional time comparison equipment

Technical Field

The invention relates to a calibration method of equipment time delay in the field of optical fiber time synchronization, in particular to a calibration method of equipment time delay asymmetry through high-precision optical fiber bidirectional time comparison.

Background

The device delay refers to the additional delay generated when a signal passes through the device, and is the inherent characteristic of the device. The high-precision optical fiber bidirectional time comparison is used for carrying out time synchronization by sending and receiving timing signals through an optical fiber link, and accurate clock error can be obtained only by deducting the time delay asymmetry of the optical fiber time comparison equipment when the accurate time synchronization precision is obtained. Therefore, the calibration precision of the time delay asymmetry of the optical fiber time synchronization equipment directly influences the precision of the optical fiber time synchronization system, and the method is a key technology of the optical fiber time synchronization system.

At present, in time synchronization based on satellites and cables, system calibration is mainly used for calibrating time delay of a system by measuring electrical time delay, and adopted equipment time delay measuring methods mainly comprise a vector network analyzer method, an oscilloscope method, a time interval counter method and the like. German federal physical technology research institute (federal physical technology research institute) proposes a method for comparing the Time delay of a device based on the bidirectional Time of an optical fiber of a satellite device (rot, m., et al, "Time transfer through optical fibers over a distance of 73km with an unlimited availability below 100ps." rolling theory 49.6(2012):772.), but the influence of the optical fiber and the cable on the accuracy of the device cannot be deducted.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a high-precision calibration method for the time delay asymmetry of the optical fiber bidirectional time comparison equipment.

Device latency refers to the time delay required for a signal to travel from an input port to an output port of a device. Dividing the time delay of the optical fiber bidirectional time comparison equipment into a transmitting link time delay and a receiving link time delay: the starting point of the transmitting link time delay is an input port of a transmitted timing signal on the equipment, and the end point of the transmitting link time delay is an optical signal output port carrying the transmitted timing signal on the equipment; the starting point of the receive link delay is the input port on the device that receives the optical signal carrying the timing signal of the other party, and the ending point is the output port of the timing signal received from the other party.

The delay of the transmitting equipment comes from the following two links of introducing the delay: time coding processing delayTime delay introduced by electro-optical conversion and optical fiber duplexers (e.g. circulators, WDM, etc.)Thus, the transmit link delay can be expressed as:

similar to the delay of the transmitting device, the delay of the receiving device comes from two delay-introducing links, that of the photoelectric conversion and the optical fiber duplexer (e.g. circulator, WDM, etc.)Time delay of time decoding circuitThus, the receive link delay can be expressed as: ${\mathrm{\τ}}_i^R={\mathrm{\τ}}_{EDi}^R+{\mathrm{\τ}}_{Ti}^R.$

the invention respectively measures the non-delay of the receiving link of the equipment (marked as equipment A and equipment B) at two ends of the bidirectional time comparison system by a combined time delay measuring methodSymmetry (i.e. the delay difference of the receive link between the two devices,) And transmit link latency (i.e.: the delay difference of the transmission link between the two devices,). On the basis, the asymmetry of the time delay of the two-fiber bidirectional time comparison equipment is further calibrated ${\mathrm{\Δ\τ}}_{AB}={\mathrm{\Δ\τ}}_{AB}^T-{\mathrm{\Δ\τ}}_{AB}^R.$

The specific technical solution of the invention is as follows:

a calibration method for time delay asymmetry of high-precision optical fiber bidirectional time comparison equipment is characterized by comprising the following steps:

firstly, establishing an optical fiber bidirectional time comparison equipment time delay calibration system by adopting a time frequency reference, a cable, an optical fiber and optical fiber bidirectional time comparison calibration equipment, high-precision time delay test equipment, first equipment to be calibrated and second equipment to be calibrated;

calibrating a receiving link time delay difference between the optical fiber bidirectional time comparison devices;

calibrating the receiving link time delay difference between the optical fiber bidirectional time comparison devices;

and fourthly, calibrating the time delay asymmetry between the optical fiber bidirectional time comparison devices.

The method comprises the following steps of establishing an optical fiber bidirectional time comparison equipment time delay calibration system, wherein the optical fiber bidirectional time comparison equipment time delay calibration system comprises a first time frequency reference, a second time frequency reference, a plurality of cables, a plurality of optical fibers, first optical fiber bidirectional time comparison calibration equipment, second optical fiber bidirectional time comparison calibration equipment, first high-precision time delay test equipment, second high-precision time delay test equipment and optical fiber bidirectional time comparison equipment i (i is A, B) to be calibrated;

the first output end of the first time-frequency reference is connected with the first input end of the first high-precision time delay testing device through a cable, the second output end of the first time-frequency reference is connected with the input end of the first optical fiber bidirectional time comparison calibration device through a cable, the output end of the first optical fiber bidirectional time comparison calibration device is connected with the input end of the optical fiber bidirectional time comparison device i (i is A, B) to be calibrated through an optical fiber, and the output end of the optical fiber bidirectional time comparison device i (i is A, B) to be calibrated is connected with the second input end of the first high-precision time delay testing device through a cable;

the first output end of the second time-frequency reference is connected with the first input end of the second high-precision time delay testing device through a cable, the second output end of the second time-frequency reference is connected with the input end of an optical fiber bidirectional time comparison device i (i is A, B) to be calibrated through a cable, the optical fiber bidirectional time comparison device i (i is A, B) to be calibrated is connected with the input end of the second optical fiber bidirectional time comparison calibrating device through an optical fiber, and the output end of the second optical fiber bidirectional time comparison calibrating device is connected with the second input end of the second high-precision time delay testing device through a cable.

Calibrating the time delay difference of a receiving link between the optical fiber bidirectional time comparison equipment, and specifically comprising the following steps;

step 2-1, dividing the timing information output by the first time frequency reference into two paths: one path of timing information is input into the high-precision time delay testing equipment through a cable; the other path of timing information is input into a first optical fiber bidirectional time comparison calibration device through a cable, an optical signal which carries the timing information and is output by the first optical fiber bidirectional time comparison calibration device is input into an optical fiber bidirectional time comparison device i (i is A, B) to be calibrated through an optical fiber, and the timing information output by the optical fiber bidirectional time comparison device i to be calibrated is input into a high-precision time delay test device through the cable;

step 2-2, when the optical fiber bidirectional time comparison equipment i to be calibrated is first equipment to be calibrated:

the timing information output by the first time frequency reference and measured by the first high-precision time delay test equipment is input to the time delay difference of the high-precision time delay test equipment through the cable, the transmission link of the first optical fiber bidirectional time comparison calibration equipment, the unidirectional time transmission link formed by the optical fiber, the receiving link of the first equipment to be calibrated and the cable, and the timing information output by the first time frequency reference

Step 2-3, when the optical fiber bidirectional time comparison equipment i to be calibrated is second equipment to be calibrated:

the timing information output by the first time frequency reference and measured by the first high-precision time delay test equipment is input to the time delay difference of the high-precision time delay test equipment through the cable, the transmission link of the first optical fiber bidirectional time comparison calibration equipment, the unidirectional time transmission link formed by the optical fiber, the receiving link of the second equipment to be calibrated and the cable, and the timing information output by the first time frequency reference

Step 2-4, calculating the time delay difference of the receiving link between the optical fiber bidirectional time comparison devicesThe formula is as follows:

${\mathrm{\Δ\τ}}_{AB}^R={\mathrm{\τ}}_A^R-{\mathrm{\τ}}_B^R.$

the step of calibrating the time delay difference of the receiving link between the optical fiber bidirectional time comparison devices comprises the following steps:

step 3-1, the timing information output by the second time frequency reference is divided into two paths: one path of timing information is input into second high-precision time delay testing equipment through a cable, the other path of timing information is input into optical fiber bidirectional time comparison equipment i to be calibrated (i is A and B) through the cable, an optical signal which carries the timing information and is output by the optical fiber bidirectional time comparison equipment i to be calibrated is input into the second optical fiber bidirectional time comparison calibrating equipment through an optical fiber, and the timing information output by the second optical fiber bidirectional time comparison calibrating equipment is input into the second high-precision time delay testing equipment through the cable;

step 3-2, when the optical fiber bidirectional time comparison device i to be calibrated is a first device to be calibrated, the second high-precision time delay test device measures the time delay difference of the timing information output by the second time frequency reference, which is input to the second high-precision time delay test device through the cable, the transmission link of the first device to be calibrated, the optical fiber, the receiving link of the second optical fiber bidirectional time comparison calibration device and the cable to form a unidirectional time transmission link, and the timing signal output by the second time frequency reference is input to the second high-precision time delay test device through the cable

Step 3-3, when the optical fiber bidirectional time comparison device i to be calibrated is a second device to be calibrated, the second high-precision time delay test device measures the timing information output by the second time frequency reference, and the timing information passes through the cable, the sending link of the second device to be calibrated, the optical fiber, the receiving link of the second optical fiber bidirectional time comparison calibration device and the cable to form a unidirectional time transmission linkTime delay difference of timing signal output by second time frequency reference and input to second high-precision time delay test equipment through cable

4) Calculating the receiving link time delay difference between the optical fiber bidirectional time comparison devicesThe formula is as follows:

${\mathrm{\Δ\τ}}_{AB}^T={\mathrm{\τ}}_A^T-{\mathrm{\τ}}_B^T.$

step ④ for calibrating the asymmetry of time delay between devices for bidirectional time alignment of optical fibers_ABThe formula is as follows

${\mathrm{\Δ\τ}}_{AB}={\mathrm{\Δ\τ}}_{AB}^T-{\mathrm{\Δ\τ}}_{AB}^R$

Wherein,in order to transmit the delay difference of the link,is the delay difference of the receiving link.

Compared with the prior art, the method and the device can simply and conveniently calibrate the asymmetry of the time delay between the optical fiber two-way time comparison devices, calibrate the asymmetry of the time delay of any time-frequency device, and effectively overcome the influence of different time delays of optical fibers or cables on the accuracy.

Drawings

FIG. 1 is a schematic diagram of a receive chain delay difference calibration;

fig. 2 is a schematic diagram of link delay difference calibration.

Detailed Description

An embodiment of the present invention is given below with reference to the accompanying drawings. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific workflow are given, but the scope of the present invention is not limited to the following embodiments.

FIG. 1 is a schematic diagram of calibrating delay inequality of a receiving link, which is mainly based on a first time-frequency reference H₁First optical fiber bidirectional time comparison calibration equipment C₁An optical fiber bidirectional time comparison device i (i is A, B) to be calibrated and a first high-precision time delay measuring device M₁Cables and optical fibers. First time frequency reference H₁The timing information output by (such as various atomic clocks) is divided into two paths. One path of timing information is input into a first high-precision time delay testing device M through a cable 1-1₁(e.g., time interval measuring instruments, oscilloscopes, etc.); the other path of timing information is input into the first optical fiber bidirectional time comparison calibration equipment C through the cable 1-2₁The first optical fiber bidirectional time comparison calibration equipment C₁When the output optical signal carrying timing information is input into the optical fiber to be calibrated in two directions through the optical fibers 1-3The timing information output by the device i is input into the first high-precision time delay measuring device M through the cables 1-4₂. When the optical fiber bidirectional time comparison equipment i to be calibrated is equipment A, first high-precision time delay testing equipment M₁Measuring a first time-frequency reference H₁The output timing information (such as 1pps) passes through the cable 1-2 and the first optical fiber bidirectional time comparison calibration device C₁The transmission link, the optical fibers 1-3, the receiving link of the device A and the cables 1-4 form a unidirectional time transfer link and a first time-frequency reference H₁The output timing signal (e.g. 1pps) is input to the first high-precision delay testing device M via the cable 1-1₁Delay difference of (2):when the optical fiber bidirectional time comparison equipment i to be calibrated is equipment B, a first time-frequency reference H is measured₁The output timing information (such as 1pps) passes through the cable 1-2 and the first optical fiber bidirectional time comparison calibration device C₁The transmission link of (1), the optical fiber (1-3), the receiving link of the device (B) and the unidirectional time transmission link formed by the cable (1-4) and the first time-frequency reference (H)₁The output timing signal (e.g. 1pps) is input to the first high-precision delay testing device M via the cable 1-1₁Delay difference of (2):will be provided withAndsubtracting the measured results to obtain the time delay difference of the receiving links of the equipment A and the B

FIG. 2 is a schematic diagram of the calibration of the delay difference of the transmission link, which is mainly based on a second time-frequency reference H₂Second optical fiber bidirectional time comparison calibration equipment C₂And a to-be-calibrated optical fiber bidirectional time comparison device i (i ═ a,B) second high-precision time delay measuring equipment M₂Cables and optical fibers. Second time frequency reference H₂The timing information output by (such as various atomic clocks) is divided into two paths of timing information and one path of timing information, and the two paths of timing information are input into a second high-precision time delay testing device M through a cable 2-1₂(e.g., time interval measuring instruments, oscilloscopes, etc.). The other path of timing information is input to an optical fiber bidirectional time comparison device i (i is A, B) to be calibrated through a cable 2-2, and an optical signal which carries the timing information and is output by i is input to a second optical fiber bidirectional time comparison calibration device C through an optical fiber 2-3₂。C₂The output timing information is input into a second high-precision time delay testing device M through cables 2-4₂. When the optical fiber bidirectional time comparison equipment i to be calibrated is equipment A, second high-precision time delay testing equipment M₂Measuring a second time-frequency reference H₂The output timing information (such as 1pps) passes through a cable 2-2, a transmission link of the equipment A, an optical fiber 2-3 and a second optical fiber bidirectional time comparison calibration equipment C₂The receiving link and the cables 2-4 form a one-way time transmission link and a second time frequency reference H₂The output timing signal (e.g. 1pps) is input to the second high-precision time delay test device M through the cable 2-1₂Delay difference of (2):when the optical fiber bidirectional time comparison equipment i to be calibrated is B, the second high-precision time delay testing equipment M₂Measuring a second time-frequency reference H₂The output timing information (such as 1pps) passes through a cable 2-2, a transmission link of the equipment B, an optical fiber 2-3 and a second optical fiber bidirectional time comparison calibration equipment C₂The receiving link and the cables 2-4 form a one-way time transmission link and a second time frequency reference H₂The output timing signal (e.g. 1pps) is input to the second high-precision time delay test device M through the cable 2-1₂Delay difference of (2):mixing the aboveAndthe result of the measurement is subtracted to obtain the time delay difference of the sending links of the equipment A and the B

Time delay difference of sending link is calibratedDelay difference of sum receiving linkThe asymmetry of the two-way time comparison equipment time delay of the two optical fibers is obtained by subtraction

Claims (4)

1. A calibration method for time delay asymmetry of high-precision optical fiber bidirectional time comparison equipment is characterized by comprising the following steps:

firstly, establishing an optical fiber bidirectional time comparison equipment time delay calibration system by adopting a time frequency reference, a cable, an optical fiber and optical fiber bidirectional time comparison calibration equipment, high-precision time delay test equipment, first equipment to be calibrated and second equipment to be calibrated; the time delay calibration system of the optical fiber bidirectional time comparison equipment comprises a first time frequency reference, a second time frequency reference, a plurality of cables, a plurality of optical fibers, first optical fiber bidirectional time comparison calibration equipment, second optical fiber bidirectional time comparison calibration equipment, first high-precision time delay test equipment, second high-precision time delay test equipment and optical fiber bidirectional time comparison equipment i (i is A, B) to be calibrated;

said first time-frequency reference (H)₁) Is connected with a first high-precision time delay test device (M) through a cable (1-1)₁) Is connected to said first input, said first time-frequency reference (H)₁) The second output end of the optical fiber is compared with the first optical fiber bidirectional time by the cable (1-2) to calibrate the equipment (C)₁) Is connected with the input end of the first optical fiber, and the first optical fiber bidirectional time comparison calibration equipment (C)₁) The output end of the optical fiber bidirectional time comparison device i (i ═ A, B) to be calibrated is connected with the input end of the optical fiber bidirectional time comparison device i (i ═ A, B) to be calibrated through the optical fibers (1-3), and the output end of the optical fiber bidirectional time comparison device i (i ═ A, B) to be calibrated is connected with the first high-precision time delay test device (M) through the cables (1-4)₁) Is connected with the second input end;

said second time-frequency reference (H)₂) The first output end of the first high-precision time delay testing device (M) is connected with a second high-precision time delay testing device (M) through a cable (2-1)₂) Is connected to the first input terminal of the first time frequency reference (H), the second time frequency reference (H)₂) The second output end of the optical fiber bidirectional time comparison device to be calibrated is connected with the input end of an optical fiber bidirectional time comparison device i (i ═ A, B) to be calibrated through a cable (2-2), and the optical fiber bidirectional time comparison device i (i ═ A, B) to be calibrated is connected with a second optical fiber bidirectional time comparison calibration device (C) through an optical fiber (2-3)₂) Is connected with the input end of the second optical fiber, and the second optical fiber is used for bidirectional time comparison and calibration equipment (C)₂) The output end of the time delay testing device (M) is connected with a second high-precision time delay testing device (M) through a cable (2-4)₂) Is connected with the second input end;

calibrating a receiving link time delay difference between the optical fiber bidirectional time comparison devices;

calibrating the time delay difference of a sending link between the optical fiber bidirectional time comparison devices;

and fourthly, calibrating the time delay asymmetry between the optical fiber bidirectional time comparison devices.

2. The calibration method of time delay asymmetry of high-precision optical fiber bidirectional time comparison equipment according to claim 1, wherein the step of calibrating the receiving link time delay difference between the optical fiber bidirectional time comparison equipment specifically comprises the following steps;

step 2-1, first time frequency reference (H)₁) The output timing information is divided into two paths: one path of timing information is input into a first high-precision time delay testing device (M) through a cable (1-1)₁) (ii) a The other path of timing information is input into the first optical fiber bidirectional time comparison calibration equipment (C) through the cable (1-2)₁) The first optical fiber bidirectional time comparison calibration equipment (C)₁) The output optical signal carrying timing information is input to an optical fiber bidirectional time comparison device i (i is A, B) to be calibrated through an optical fiber (1-3), and the timing information output by the optical fiber bidirectional time comparison device i to be calibrated is input to a first high-precision time delay test device (M) through a cable (1-4)₁)；

Step 2-2, when the optical fiber bidirectional time comparison equipment i to be calibrated is first equipment (A) to be calibrated:

first high-precision time delay test equipment (M)₁) Measuring a first time frequency reference (H)₁) The output timing information passes through the cable (1-2) and the first optical fiber bidirectional time comparison calibration equipment (C)₁) A unidirectional time transfer link formed by the transmitting link, the optical fiber (1-3), the receiving link of the first device (A) to be calibrated and the cable (1-4) and a first time-frequency reference (H)₁) The output timing information is input to a first high-precision time delay test device (M) through a cable (1-1)₁) Time delay difference of

Step 2-3, when the optical fiber bidirectional time comparison equipment i to be calibrated is second equipment (B) to be calibrated:

first high-precision time delay test equipment (M)₁) Measuring a first time frequency reference (H)₁) The output timing information passes through the cable (1-2) and the first optical fiber bidirectional time comparison calibration equipment (C)₁) A unidirectional time transfer link formed by the transmitting link, the optical fiber (1-3), the receiving link of the second device (B) to be calibrated and the cable (1-4) and a first time-frequency reference (H)₁) The outputted timing information is inputted to the second terminal through a cable (1-1)High-precision time delay test equipment (M)₁) Time delay difference of

Step 2-4, calculating the time delay difference of the receiving link between the optical fiber bidirectional time comparison devicesThe formula is as follows:

${\mathrm{\Δ\τ}}_{AB}^R={\mathrm{\τ}}_A^R-{\mathrm{\τ}}_B^R.$

3. the method for calibrating time delay asymmetry of high-precision optical fiber bidirectional time comparison equipment according to claim 1, wherein said step (c) of calibrating transmission link time delay difference between optical fiber bidirectional time comparison equipment comprises the steps of:

step 3-1, second time frequency reference (H)₂) The output timing information is divided into two paths: one path of timing information is input into a second high-precision time delay testing device (M) through a cable (2-1)₂) The other path of timing information is input to an optical fiber bidirectional time comparison device i to be calibrated (i is A, B) through a cable (2-2), and an optical signal carrying the timing information and output by the optical fiber bidirectional time comparison device i to be calibrated is input to a second optical fiber bidirectional time comparison calibration device (C) through an optical fiber (2-3)₂) Second optical fiber bidirectional time comparison calibration equipment (C)₂) The output timing information is input to a second high-precision time delay test device (M) through cables (2-4)₂)；

Step 3-2, when the optical fiber bidirectional time comparison equipment i to be calibrated is first equipment (A) to be calibrated:

second high precision time delay test equipment (M)₂) Measuring a second time-frequency reference (H)₂) The output timing information passes through a cable (2-2), a transmission link of a first device to be calibrated (A), an optical fiber (2-3) and a second optical fiber bidirectional time comparison calibration device (C)₂) The receiving link and the cables (2-4) form a unidirectional time transfer link and a second time frequency reference (H)₂) The output timing signal is input to a second high-precision time delay test device (M) through a cable (2-1)₂) Time delay difference of

3-3, when the to-be-calibrated optical fiber bidirectional time comparison equipment i is first to-be-calibrated equipment (B):

second high precision time delay test equipment (M)₂) Measuring a second time-frequency reference (H)₂) The output timing information passes through a cable (2-2), a transmission link of a second device to be calibrated (B), an optical fiber (2-3) and a second optical fiber bidirectional time comparison calibration device (C)₂) The receiving link and the cables (2-4) form a unidirectional time transfer link and a second time frequency reference (H)₂) The output timing signal is input to a second high-precision time delay test device (M) through a cable (2-1)₂) Time delay difference of

Step 3-4, calculating the time delay difference of the sending link between the optical fiber bidirectional time comparison devicesThe formula is as follows:

${\mathrm{\Δ\τ}}_{AB}^T={\mathrm{\τ}}_A^T-{\mathrm{\τ}}_B^T.$

4. the method according to claim 1, wherein said step ④ is performed to calibrate the time delay asymmetry between the optical fiber bidirectional time comparison devices_ABThe formula is as follows

${\mathrm{\Δ\τ}}_{AB}={\mathrm{\Δ\τ}}_{AB}^T-{\mathrm{\Δ\τ}}_{AB}^R$

Wherein,in order to transmit the delay difference of the link,is the delay difference of the receiving link.