Link delay measuring device and method in serial cascade optical fiber ring network architecture

Abstract

The invention relates to a link delay measuring device and method in a serial cascade optical fiber ring network architecture, and the device comprises a host and a plurality of extensions, and the host and the extensions are connected end to end in an optical fiber ring network in series to form a ring network. The host sends time-frequency reference information through the ring network, and the extensions receive and synchronize the time-frequency reference information of the host and forward the information of the host to the next-level extensions until the information returns to the host, so that a closed loop is completed; the extension synchronizes host time frequency information to establish a local time reference, reports a synchronization state, receives host control information, feeds back a second pulse signal containing link delay information through a looped network reverse link, and the host completes reference second pulse signal generation, link delay measurement and data processing. According to the invention, the problem of precision loss of the output time service signal caused by inconsistent link lengths of the time frequency reference equipment under the optical fiber ring network architecture can be solved, and the accuracy, consistency and reliability of the time service signal output by the time frequency reference equipment based on the optical fiber ring network architecture can be improved to a greater extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of time-frequency transfer, and in particular to a link delay measurement device and method in a serial cascade optical fiber ring network architecture. Background Art

[0002] At present, the time and frequency reference equipment based on the fiber optic ring network architecture consists of a host and extensions. The host and extensions communicate through the fiber optic ring network. When there are a large number of serial cascade devices inside the fiber optic ring network and the distance between the devices is far, if the link delay caused by the internal optical cable cannot be accurately calibrated, the consistency of the timing information output by the host and extension will be destroyed, affecting the synchronization accuracy of the timing equipment and thus destroying the entire time and frequency synchronization system. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a link delay measurement device and method in a serial cascade fiber optic ring network architecture, which can solve the problem of loss of accuracy of the output timing signal of the time and frequency reference device due to inconsistent link lengths in the fiber optic ring network architecture, and can greatly improve the accuracy, consistency and reliability of the timing signal output by the time and frequency reference device in the fiber optic ring network architecture.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A link delay measurement device in a serial cascade optical fiber ring network architecture comprises a host and multiple extensions, wherein the host and the extensions are connected end to end in a serial manner inside the optical fiber ring network to form a ring network; the host is used to send time and frequency reference information through the ring network, and the extension is used to receive and synchronize the host time and frequency reference information, and at the same time forward the host information to the extension of the next level until it returns to the host to complete a closed loop; the extension synchronizes the host time and frequency information to establish a local time reference, reports the synchronization status, receives the host control information, and feeds back a second pulse signal through the reverse link of the ring network, and the host completes the generation of the reference second pulse signal, link delay measurement and data processing.

[0006] Moreover, the host includes a second pulse generating unit, a phase detection unit, a core control unit, a frequency reference unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the core control unit and the second pulse generating unit, the second pulse generating unit is respectively connected to the phase detection unit and the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the optical switch unit, the phase detection unit and the second pulse generating unit, and the photoelectric conversion unit is connected to the optical switch unit.

[0007] Moreover, the extension includes a second pulse generating unit, a second pulse synchronization unit, a phase detection unit, a core control unit, a frequency reference unit, a phase shift unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the second pulse generating unit, the core control unit and the second pulse synchronization unit, the second pulse generating unit is respectively connected to the phase shift unit and the core control unit, the phase shift unit is connected to the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the second pulse synchronization unit, the phase detection unit and the optical switch unit, the photoelectric conversion unit is connected to the optical switch unit, and the second pulse synchronization unit is connected to the phase detection unit.

[0008] Moreover, the second pulse synchronization unit includes a D flip-flop and a phase shift unit, wherein the clock input of the D flip-flop is a frequency signal provided by the frequency reference unit; the second pulse synchronization unit is used to generate a second pulse signal that lags behind the external input second pulse by 0 to 1 clock cycle and is in phase with the internal frequency signal;

[0009] The phase detection unit measures the time difference between the internal second pulse and the input second pulse, and provides this time difference data to the phase shift unit. The phase shift unit adjusts the phase of the internal second pulse signal through a closed-loop feedback control method to obtain a second pulse signal that is strictly consistent with the phase of the external input second pulse signal.

[0010] Moreover, the second pulse generation unit generates a device reference second pulse signal by counting the frequency reference signal input to the frequency reference unit;

[0011] The frequency reference unit includes a reference frequency standard and a clock fan-out circuit. The reference frequency standard is used to provide a standard frequency output. The clock fan-out circuit expands a single-channel output into multiple-channel outputs for use by other units.

[0012] Furthermore, the optical switch unit changes the internal optical path by turning off and on the optical switch, thereby realizing the operation of adding and removing the main and extension units from the optical fiber ring network;

[0013] The photoelectric conversion unit can complete the photoelectric and electro-optical signal conversion, and then the optical switch completes the loop control.

[0014] Moreover, the core control unit adopts a processor. The core control unit drives the phase detection unit in the extension to measure the phase difference between the input second pulse and the internal second pulse, and drives the phase shifting unit according to the phase difference to complete phase feedback control and realize high-precision synchronization of the phase of the extension input and output second pulse signals.

[0015] A working method of a link delay measurement device in a serial cascade optical fiber ring network architecture comprises a host completing the link delay measurement in the serial cascade optical fiber ring network architecture and an extension completing the link delay measurement in the serial cascade optical fiber ring network architecture.

[0016] Moreover, the host completes the link delay measurement in the serial cascade optical fiber ring network architecture, including the following steps:

[0017] Step 1.1, the host starts working, turns on the internal optical switch module, and uses the frequency reference unit signal to establish a time reference;

[0018] Step 1.2, sending the time and frequency reference information to the optical fiber ring network, receiving the synchronization status and working status fed back by the extension, sending the extension optoelectronic conversion unit control word, summarizing the extension status and judging the optical fiber link status according to whether the communication message is received;

[0019] Step 1.3, according to the extension status, measure the phase difference between the reference second pulse signal and the extension feedback second pulse signal in turn, and calculate the average phase difference of each device to form a data set;

[0020] Step 1.4: After obtaining a valid data set, distribute the delay data to each extension. After compensation by the extension, return to step 1.3 to continue measuring until the measured phase difference result meets the threshold requirement. The calibration of a single extension is completed, and the calibration process of the next extension is entered until all extensions are calibrated and the process ends.

[0021] Moreover, the extension completes the link delay measurement in the serial cascade optical fiber ring network architecture, including the following steps:

[0022] Step 2.1, the extension starts working, turns on the internal optical switch unit, and determines whether the host communication message is received. If the communication message is received, execute step 2.2, otherwise repeat step 2.1;

[0023] Step 2.2: When the extension is connected to the network, synchronize the time and frequency information in the optical fiber ring network, establish the extension time reference system based on the ring network frequency signal, and report the synchronization status to the host;

[0024] Step 2.3, waiting for the host control command, sending the adjusted second pulse signal back to the host through the reverse link, and recording the delay compensation value fed back by the host;

[0025] Step 2.4: Compensate the delay into the output pulse-per-second signal according to the host instruction. If the feedback measurement process is not completed, the extension returns to step 2.3 to adjust the output pulse-per-second phase according to the host delay measurement result until the threshold requirement is met and enters step 2.5;

[0026] Step 2.5: After a single extension completes calibration, it will no longer feedback the pulse-per-second signal. The ring network is controlled by the host to enter the link delay calibration process of the next extension. The extension that has completed the calibration will forward data and report the status until the host completes the delay calibration of all extensions, and the process ends.

[0027] The advantages and positive effects of the present invention are:

[0028] The present invention includes a host and multiple extensions, wherein the host and the extensions are connected end to end in a series manner inside a fiber optic ring network to form a ring network; the host is used to send time and frequency reference information through the ring network, and the extension is used to receive and synchronize the host time and frequency reference information, and at the same time forward the host information to the next-level extension until it returns to the host to complete a closed loop; the extension synchronizes the host time and frequency information to establish a local time reference, report the synchronization status, receive the host control information, and feedback the second pulse signal through the reverse link of the ring network. The host completes the generation of the reference second pulse signal, link delay measurement and data processing. The present invention has the advantages of independent measurement of device link delay, no limitation on the number of access devices, high measurement accuracy, and easy implementation. It can solve the problem of output timing signal accuracy loss caused by inconsistent link length of the time and frequency reference device under the fiber optic ring network architecture, and can greatly improve the accuracy, consistency and reliability of the output timing signal of the time and frequency reference device based on the fiber optic ring network architecture. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the composition of the serial cascade optical fiber ring network link in the present invention;

[0030] Figure 2 This is a schematic diagram of the mainframe functional unit composition in the present invention;

[0031] Figure 3 It is a schematic diagram of the extension function unit in the present invention;

[0032] Figure 4 It is a flowchart of the host link delay measurement information processing process in the present invention;

[0033] Figure 5 The figure is a flow chart of the extension link delay measurement information processing process in the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to the accompanying drawings.

[0035] A link delay measurement device in a serial cascade optical fiber ring network architecture, such as Figure 1 As shown, it includes a host and multiple extensions, wherein the host and the extensions are connected end to end in series inside the optical fiber ring network to form a ring network; the host is used to send time and frequency reference information through the ring network, and the extension is used to receive and synchronize the host time and frequency reference information, and at the same time forward the host information to the next-level extension until it returns to the host to complete the closed loop; the extension synchronizes the host time and frequency information to establish a local time reference, reports the synchronization status, receives the host control information, and feeds back the second pulse signal through the reverse link of the ring network. The host completes the reference second pulse signal generation, link delay measurement and data processing.

[0036] like Figure 2As shown, the host includes a second pulse generating unit, a phase detection unit, a core control unit, a frequency reference unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the core control unit and the second pulse generating unit, the second pulse generating unit is respectively connected to the phase detection unit and the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the optical switch unit, the phase detection unit and the second pulse generating unit, and the photoelectric conversion unit is connected to the optical switch unit.

[0037] like Figure 3 As shown, the extension includes a second pulse generating unit, a second pulse synchronization unit, a phase detection unit, a core control unit, a frequency reference unit, a phase shift unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the second pulse generating unit, the core control unit and the second pulse synchronization unit, the second pulse generating unit is respectively connected to the phase shift unit and the core control unit, the phase shift unit is connected to the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the second pulse synchronization unit, the phase detection unit and the optical switch unit, the photoelectric conversion unit is connected to the optical switch unit, and the second pulse synchronization unit is connected to the phase detection unit.

[0038] Among them, the second pulse synchronization unit is used in the extension, which is constructed by a D flip-flop and a phase shift unit. The clock input of the D flip-flop is the frequency signal provided by the frequency reference unit; this unit is used to generate a second pulse signal that lags behind the external input second pulse by 0 to 1 clock cycle and is in phase with the internal frequency signal.

[0039] The phase detection unit in the extension measures the time difference between the internal second pulse and the input second pulse, and provides this time difference data to the phase shift unit. The phase shift unit adjusts the phase of the internal second pulse signal through a closed-loop feedback control method to obtain a second pulse signal that is strictly consistent with the phase of the external input second pulse signal.

[0040] The second pulse generation unit generates a device reference second pulse signal by counting the frequency reference signal input to the frequency reference unit.

[0041] The frequency reference unit consists of a reference frequency standard (including but not limited to atomic clocks, crystal oscillators, and crystals) and a clock fan-out circuit. The reference frequency standard provides a standard frequency output, and the clock fan-out circuit expands the single-channel output into multiple-channel outputs for use by other units.

[0042] The core control unit is implemented by a processor (including but not limited to single-chip microcomputer, CPU, DSP, FPGA). The core control unit drives the phase detection unit in the extension to measure the phase difference between the input second pulse and the internal second pulse, and drives the phase shift unit according to the phase difference to complete the phase feedback control, so as to achieve high-precision synchronization of the phase of the input and output second pulse signals of the extension. The extension core control unit receives the host control information from the optical fiber ring network to control the optical switch unit and the photoelectric conversion unit to ensure that the optical fiber loop is time-division multiplexed during the measurement process, and the host only measures the link delay of one extension within a period of time; the core control unit drives the phase detection unit in the host to measure the phase difference between the host reference second pulse signal and the second pulse signal after synchronization of the extension feedback, so as to calculate the optical fiber link delay, and send control information to each extension at the same time to ensure that only one extension in the loop feeds back the synchronized second pulse signal to avoid erroneous measurement.

[0043] The phase detection unit is driven by the core control unit to measure the phase difference between the rising edges of the two input signals. The phase shift unit is driven by the core control unit to fine-tune the phase of the input signal within 0 to 1 clock cycle.

[0044] The optical switch unit changes the internal optical path by turning off and on the optical switch, and can realize the operation of adding and removing the main and extension units from the optical fiber ring network.

[0045] The photoelectric conversion unit can complete the photoelectric and electro-optical signal conversion, and then the optical switch completes the loop control.

[0046] A working method of a link delay measurement device in a serial cascade optical fiber ring network architecture comprises a host completing the link delay measurement in the serial cascade optical fiber ring network architecture and an extension completing the link delay measurement in the serial cascade optical fiber ring network architecture.

[0047] like Figure 4 As shown, the host completes the link delay measurement in the serial cascade optical fiber ring network architecture including the following steps:

[0048] Step 1.1, the host starts working, turns on the internal optical switch module, and uses the frequency reference unit signal to establish a time reference;

[0049] Step 1.2, sending the time and frequency reference information to the optical fiber ring network, receiving the synchronization status and working status fed back by the extension, sending the extension optoelectronic conversion unit control word, summarizing the extension status and judging the optical fiber link status according to whether the communication message is received;

[0050] Step 1.3, according to the extension status, measure the phase difference between the reference second pulse signal and the extension feedback second pulse signal in turn, and calculate the average phase difference of each device to form a data set;

[0051] Step 1.4: After obtaining a valid data set, distribute the delay data to each extension. After compensation by the extension, return to step 1.3 to continue measuring until the measured phase difference result meets the threshold requirement. The calibration of a single extension is completed, and the calibration process of the next extension is entered until all extensions are calibrated and the process ends.

[0052] like Figure 5 As shown, the extension completes the link delay measurement in the serial cascade optical fiber ring network architecture including the following steps:

[0053] Step 2.1, the extension starts working, turns on the internal optical switch unit, and determines whether the host communication message is received. If the communication message is received, execute step 2.2, otherwise repeat step 2.1;

[0054] Step 2.2: When the extension is connected to the network, synchronize the time and frequency information in the optical fiber ring network, establish the extension time reference system based on the ring network frequency signal, and report the synchronization status to the host;

[0055] Step 2.3, waiting for the host control command, sending the adjusted second pulse signal back to the host through the reverse link, and recording the delay compensation value fed back by the host;

[0056] Step 2.4: Compensate the delay into the output pulse-per-second signal according to the host instruction. If the feedback measurement process is not completed, the extension returns to step 2.3 to adjust the output pulse-per-second phase according to the host delay measurement result until the threshold requirement is met and enters step 2.5;

[0057] Step 2.5: After a single extension completes calibration, it will no longer feedback the pulse-per-second signal. The ring network is controlled by the host to enter the link delay calibration process of the next extension. The extension that has completed the calibration will forward data and report the status until the host completes the delay calibration of all extensions, and the process ends.

[0058] Example

[0059] According to the above-mentioned link delay measurement device and method in a serial cascade optical fiber ring network architecture, the effect of the present invention is verified by constructing a device to measure the link delay value and the synchronization accuracy of the second pulse signal output by the main extension after compensation.

[0060] like Figure 1As shown, the N value is 4. In the embodiment of the present invention, 1 host and 4 extensions are included. The host and the extension form a ring network through optical fiber. After the extension establishes a local time reference system, the second pulse signal is fed back to the host. The host measures the phase difference between the reference second pulse signal and the second pulse signal fed back by the extension, obtains a measurement result once per second, and takes the average after obtaining 10 valid results in succession. Due to the symmetry of the optical fiber link, it is considered that the link delay is 1 / 2 of the average result. After the host completes the delay result calculation, the delay value is sent to the extension for compensation. After the extension is compensated, the host performs phase measurement again. After compensation, the second pulse output consistency error threshold is set to 4ns. If the phase difference between the extension and the reference second pulse signal after compensation is better than 4ns, the compensation process of this extension is terminated, the compensation result is solidified, and the link delay test of the next extension is performed; if the threshold requirement is not met, the original compensation value is cleared and the extension is measured again until all extensions complete the link delay compensation, that is, the complete link calibration process is completed.

[0061] In this embodiment, the calibration process of extension 1, extension 2, extension 3 and extension 4 is taken as an example, which specifically includes the following steps:

[0062] like Figure 4 As shown in the figure, the host link delay measurement includes the following steps:

[0063] (1) The host is powered on, the internal optical switch module is enabled, and after the internal frequency reference unit is locked, the internal second pulse reference information is generated by frequency signal counting;

[0064] (2) Encoding the internal second pulse signal, frequency signal, and control word of each extension and sending them to the optical fiber ring network, receiving the synchronization status and working status fed back by the extension, summarizing the extension status to determine whether each extension is working normally and whether the ring network is connected, and in the case of disconnection, troubleshooting the abnormal optical fiber link through the human-computer interaction interface, and waiting for the ring network to be completely normal, then entering step (3) to start measuring the extension link delay, otherwise, it remains in step (2);

[0065] (3) First, confirm the synchronization status fed back by extension 1. After extension 1 establishes the local time reference, it feeds back the pulse-per-second signal to the host. The host continuously measures the phase difference between the pulse-per-second signals, calculates the average of 10 measurement results, and uses 1 / 2 of the average as the link delay, which is fed back to extension 1 through the specific field of the control word. After receiving the link delay, extension 1 compensates for the output pulse-per-second signal and reports the status after the compensation is completed.

[0066] (4) The host again measures the phase difference between the local reference second pulse signal and the compensated second pulse signal fed back by extension 1. If the phase difference is better than 4 ns at this time, it is considered that the compensation value measurement is accurate. After the result is solidified, the extension 2 delay measurement is continued. Otherwise, the extension 1 compensation value is reset to zero and the measurement is repeated until the extension 1 compensation result meets the 4 ns threshold requirement.

[0067] (5) After four rounds of steps (3) to (4), the link delay compensation values ​​of extensions 1 to 4 all meet the requirements, and the host displays the link delay results through the human-computer interaction interface, and the host measurement process ends.

[0068] like Figure 5 As shown in the figure, the extension completes the link delay measurement including the following steps:

[0069] (1) Extension 1 is powered on, the internal optical switch unit is enabled, and it is determined whether a host communication message is received. If a communication message is received, step (2) is executed; otherwise, step (1) is always executed;

[0070] (2) When extension 1 is connected to the network, it synchronizes the time and frequency information in the optical fiber ring network, and generates a reference second pulse signal that is strictly synchronized with the optical fiber second pulse signal through a closed-loop feedback second pulse synchronization method based on the ring network frequency signal;

[0071] (3) After establishing the time base of extension 1, the synchronization status is reported to the host through the control word part;

[0072] (4) Wait for the host control command and feed back the reference second pulse signal of extension 1 to the host through the reverse link;

[0073] (5) receiving the delay result compensation output pulse-per-second signal sent by the host, and further waiting for the host control instruction to feed back the compensated pulse-per-second signal to the host through the reverse link;

[0074] (6) Waiting for the host's measurement completion instruction. If the host determines that the compensation result of extension 1 meets the threshold requirement, it will change the control word of extension 1 so that extension 1 only completes signal forwarding and status reporting in the ring network and no longer feeds back second pulses. The ring network enters the extension 2 compensation process. Otherwise, extension 1 will reset the compensation value and return to step 4 until the compensation result meets the threshold requirement.

[0075] (7) After extensions 2 to 4 complete steps 2 to 6 respectively, all extensions complete compensation and the extension measurement process ends.

[0076] The measured link delay value and the measured synchronization accuracy of the master and extension output pulse-per-second signal after compensation are shown in Table 1:

[0077] Table 1 Measured link delay value and measured master / extension output second pulse signal synchronization accuracy after compensation in the embodiment

[0078] name Link delay Delay measurement value after compensation Output compensation value Synchronization accuracy Host / / / 0ns(benchmark) Extension 1 370ns 3ns(4ns threshold) 185ns ≤6ns Extension 2 699ns 2ns(4ns threshold) 350ns ≤4ns Extension 3 1053ns 1ns(4ns threshold) 527ns ≤5ns Extension 4 1920ns 2ns(4ns threshold) 810ns ≤4ns

[0079] As shown in Table 1, the measured link delay value and the measured consistency result of the master-extension output second pulse signal after compensation in the embodiment of the present invention, therefore, the present invention can solve the problem of loss of accuracy of the output timing signal of the time-frequency reference device due to inconsistent link lengths in the optical fiber ring network architecture, and can greatly improve the accuracy, consistency and reliability of the timing signal output by the time-frequency reference device in the optical fiber ring network architecture.

[0080] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A link delay measurement device in a serial cascade optical fiber ring network architecture, characterized in that: It includes a host and multiple extensions, wherein the host and the extensions are connected end to end in series inside the optical fiber ring network to form a ring network; the host is used to send time and frequency reference information through the ring network, and the extension is used to receive and synchronize the host time and frequency reference information, and at the same time forward the host information to the next-level extension until it returns to the host to complete the closed loop; the extension synchronizes the host time and frequency information to establish a local time reference, reports the synchronization status, receives the host control information, and feeds back the second pulse signal containing the link delay information through the ring network reverse link. The host completes the reference second pulse signal generation, link delay measurement and data processing.

2. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 1, characterized in that: The host includes a second pulse generating unit, a phase detection unit, a core control unit, a frequency reference unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the core control unit and the second pulse generating unit, the second pulse generating unit is respectively connected to the phase detection unit and the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the optical switch unit, the phase detection unit and the second pulse generating unit, and the photoelectric conversion unit is connected to the optical switch unit.

3. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 1, characterized in that: The extension includes a second pulse generating unit, a second pulse synchronization unit, a phase detection unit, a core control unit, a frequency reference unit, a phase shift unit, an optical switch unit and a photoelectric conversion unit, wherein the frequency reference unit is respectively connected to the second pulse generating unit, the core control unit and the second pulse synchronization unit, the second pulse generating unit is respectively connected to the phase shift unit and the core control unit, the phase shift unit is connected to the core control unit, the core control unit is respectively connected to the photoelectric conversion unit, the second pulse synchronization unit, the phase detection unit and the optical switch unit, the photoelectric conversion unit is connected to the optical switch unit, and the second pulse synchronization unit is connected to the phase detection unit.

4. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 3, characterized in that: The second pulse synchronization unit includes a D flip-flop and a phase shift unit, wherein the clock input of the D flip-flop is a frequency signal provided by the frequency reference unit; the second pulse synchronization unit is used to generate a second pulse signal that lags behind the external input second pulse by 0 to 1 clock cycle and is in phase with the internal frequency signal; The phase detection unit measures the time difference between the internal second pulse and the input second pulse, and provides this time difference data to the phase shift unit. The phase shift unit adjusts the phase of the internal second pulse signal through a closed-loop feedback control method to obtain a second pulse signal that is strictly consistent with the phase of the external input second pulse signal.

5. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 3, characterized in that: The second pulse generation unit generates a device reference second pulse signal by counting the frequency reference signal input to the frequency reference unit; The frequency reference unit includes a reference frequency standard and a clock fan-out circuit. The reference frequency standard is used to provide a standard frequency output. The clock fan-out circuit expands a single-channel output into multiple-channel outputs for use by other units.

6. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 3, characterized in that: The optical switch unit changes the internal optical path by turning off and on the optical switch, thereby realizing the operation of adding and removing the main and extension units from the optical fiber ring network; The photoelectric conversion unit can complete the photoelectric and electro-optical signal conversion, and then the optical switch completes the loop control.

7. The link delay measurement device in a serial cascade optical fiber ring network architecture according to claim 3, characterized in that: The core control unit adopts a processor. The core control unit drives the phase detection unit in the extension to measure the phase difference between the input second pulse and the internal second pulse, and drives the phase shift unit according to the phase difference to complete phase feedback control and realize high-precision synchronization of the phase of the extension input and output second pulse signals.

8. A working method of the time synchronization signal hybrid encoding device in a burst optical fiber ring network according to any one of claims 1 to 7, characterized in that: The invention includes the host completing the link delay measurement in the serial cascade optical fiber ring network architecture and the extension completing the link delay measurement in the serial cascade optical fiber ring network architecture.

9. The working method of the link delay measurement device in the serial cascade optical fiber ring network architecture according to claim 7, characterized in that: The host completes the link delay measurement in the serial cascade optical fiber ring network architecture, including the following steps: Step 1.1, the host starts working, turns on the internal optical switch module, and uses the frequency reference unit signal to establish a time reference; Step 1.2, sending the time and frequency reference information to the optical fiber ring network, receiving the synchronization status and working status fed back by the extension, sending the extension optoelectronic conversion unit control word, summarizing the extension status and judging the optical fiber link status according to whether the communication message is received; Step 1.3, according to the extension status, measure the phase difference between the reference second pulse signal and the extension feedback second pulse signal in turn, and calculate the average phase difference of each device to form a data set; Step 1.4: After obtaining a valid data set, distribute the delay data to each extension. After compensation by the extension, return to step 1.3 to continue measuring until the measured phase difference result meets the threshold requirement. The calibration of a single extension is completed, and the calibration process of the next extension is entered until all extensions are calibrated and the process ends.

10. The working method of the link delay measurement device in the serial cascade optical fiber ring network architecture according to claim 1, characterized in that: The extension completes the link delay measurement in the serial cascade optical fiber ring network architecture, including the following steps: Step 2.1, the extension starts working, turns on the internal optical switch unit, and determines whether the host communication message is received. If the communication message is received, execute step 2.2, otherwise repeat step 2.1; Step 2.2: When the extension is connected to the network, synchronize the time and frequency information in the optical fiber ring network, establish the extension time reference system based on the ring network frequency signal, and report the synchronization status to the host; Step 2.3, waiting for the host control command, sending the adjusted second pulse signal back to the host through the reverse link, and recording the delay compensation value fed back by the host; Step 2.4: Compensate the delay into the output pulse-per-second signal according to the host instruction. If the feedback measurement process is not completed, the extension returns to step 2.3 to adjust the output pulse-per-second phase according to the host delay measurement result until the threshold requirement is met and enters step 2.5; Step 2.5: After a single extension completes calibration, it will no longer feedback the pulse-per-second signal. The ring network is controlled by the host to enter the link delay calibration process of the next extension. The extension that has completed the calibration will forward data and report the status until the host completes the delay calibration of all extensions, and the process ends.

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