JP2016014571A - Time information transmission system, transmitter, and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit precise time information or clock signal from a transmitter to a receiver.SOLUTION: In a time information transmission system, where a transmitter 10 receives an exact second signal indicating time information received at a predetermined period from the outside at a period T later than the time information and transmits an information signal including time information to a receiver 20 at the period T, the transmitter 10 includes a delay time acquisition part 15 for acquiring signal delay time t1 by a transmission line, an operation part 17 for generating delay time designation information by calculating delay time t2 by using the signal delay time t1, and a frame information transmission part for generating and transmitting frame information including time information and delay time designation information. The receiver 20 includes a decoding part 21 for taking out reference timing from the received frame information to restore time information and delay time designation information, and a clock part 25 for outputting actual time information by setting time information to a clock circuit at accurate clock timing based on reference timing, and the delay time t2 within the delay time designation information.

Description

  The present invention relates to a time information transmission technique for transmitting accurate time information from a GPS (Global Positioning System) receiver or the like.

  For example, in an earthquake or tsunami observation system, it is required to give accurate time information to data collected by an observation device installed at an observation point. Therefore, accurate time information acquired from the GPS receiver is used as a time stamp of the observation data. However, when the observation device is installed on the seabed or the like, it is difficult to directly acquire GPS time information in the observation device. Therefore, when analyzing the observation data transmitted from the observation apparatus in the land analysis apparatus, the time information given by the observation apparatus is converted into accurate GPS time information. Therefore, it is difficult to analyze observation data in real time.

  Moreover, in an earthquake or tsunami observation system, the accuracy of the clock signal used for measurement by the observation device greatly affects the quality of the measurement result. Therefore, a thermostat type oscillator is used in the observation device to improve the frequency accuracy. However, since power consumption is large, it is difficult to supply power when the observation point is in the deep sea of several thousand meters.

  In Patent Document 1 below, in an observation system that generates time information from GPS radio waves at a land station and transmits the time information to a submarine station having an observation device via a communication cable, delay information caused by the communication cable is disclosed. Is transmitted from the land station to the submarine station, and the time information is corrected based on the delay information.

JP 2011-80885 A

  An object of the present invention is to transmit accurate time information or a clock signal from a transmission device to a reception device.

A typical configuration of the time information transmission system of the present invention for solving the above-described problems is as follows. That is,
The time information is received from the outside at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information, and an information signal including the time information is received. A time information transmission system comprising: a transmission device that transmits at the period T; and a reception device that receives the information signal from the transmission device via a transmission path,
The transmitter is
A delay time acquisition unit for acquiring a signal delay time t1 by the transmission line;
A calculation unit that calculates a delay time t2 using the signal delay time t1 and generates delay time designation information including the delay time t2,
A frame information transmission unit that generates frame information including the time information and the delay time designation information and transmits the frame information as the information signal;
The receiving device is:
A decoding unit that extracts, from the frame information received from the transmission device, a reference timing that serves as a reference for extracting a correct second timing that is the same as the correct second signal timing, and that restores the time information and the delay time designation information When,
Based on the reference timing and the delay time t2 included in the delay time designation information, the true second timing is extracted, the time information is set in the clock circuit at the true second timing, and the real time information is obtained from the clock circuit. A clock part to output,
A time information transmission system comprising:

A typical configuration of the transmission apparatus of the present invention for solving the above-described problems is as follows. That is,
The time information is received from the outside at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information, and an information signal including the time information is received. A transmission device for transmitting in the period T,
A processing clock signal generator for generating a processing clock signal;
A delay time acquisition unit for acquiring a signal delay time t1 by the transmission line;
A calculation unit that calculates a delay time t2 using the signal delay time t1 and generates delay time designation information including the delay time t2,
Frame information including the time information and the delay time designation information is generated, the frame information is encoded using the processing clock signal, and the time information, the delay time designation information, and the processing clock signal are separated. A frame information transmitter for transmitting as an information signal including a reference clock signal that has been rotated;
A transmission device comprising:

A typical configuration of the receiving apparatus of the present invention for solving the above-described problems is as follows. That is,
From the outside, the time information is received at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information from the transmission device via the transmission path. Receiving the first frame information including the time information or the second frame information including the time information and delay time designation information in the period T,
A decoding unit that extracts the reference timing from the second frame information received from the transmission device and restores the time information and the delay time designation information;
Based on the reference timing and the delay time t2 included in the delay time designation information, the correct second timing of the same timing as the correct second signal timing is taken, and the time information is set in the clock circuit at the correct second timing, A clock unit for outputting real time information from the clock circuit;
A receiving apparatus comprising:

  According to the above configuration, accurate time information or a clock signal can be transmitted from the transmission device to the reception device.

It is a figure which shows the structure of the time information transmission system which concerns on 1st Embodiment of this invention. It is a figure which shows the operation timing which concerns on 1st Embodiment of this invention. It is explanatory drawing of the transmission frame for time information, etc. which concern on 1st Embodiment of this invention. It is a figure which shows the structure of the time information transmission system which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the time information transmission system which concerns on 3rd Embodiment of this invention.

(First embodiment)
A time information transmission system according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a configuration of a time information transmission system according to the first embodiment of the present invention, and is a block diagram for realizing the functions of the system. FIG. 2 is a diagram illustrating operation timing according to the first embodiment. FIG. 3 is an explanatory diagram of a time information transmission frame and the like according to the first embodiment.

  As shown in FIG. 1, this time information transmission system is a transmission path for communication connection between a transmission device 10 that transmits time information, a reception device 20 that receives time information, and the transmission device 10 and the reception device 20. The communication cable 51 is included. For example, the transmission device 10 is included in a land station device installed on land, and the reception device 20 is included in a sea floor station device installed on the sea floor. The land station device includes a GPS receiver, and the submarine station device includes an earthquake and tsunami observation device. The length of the communication cable 51 is, for example, several tens of meters to several hundreds of kilometers.

First, an outline of the operation of this time information transmission system will be described.
The transmission device 10 periodically receives accurate time information d0 and the second signal s0 from the GPS receiver, and in this embodiment, receives each second (cycle T = 1 second). The time information d0 includes information on year / month / day / hour / second. The true second signal s0 is a pulse (500 ms width in this example) transmitted from the GPS receiver at intervals of 1 second, and indicates the actual timing (actual timing) indicated by the time information d0. Accordingly, the second signal s0 is received with a predetermined time delay from the time information d0 indicating the time of the timing indicated by the second signal s0.

  In addition, the transmission device 10 receives a precision clock signal c0 that is a clock signal with high frequency accuracy from the GPS receiver. The precision clock signal c0 is a clock signal for generating the processing clock signal c2. The processing clock signal c2 is a clock signal used for the transmission device 10 and the reception device 20 to perform various processing operations.

  The transmitter 10 generates frame information d1 every time it receives the time information d0 and the second signal s0 from the GPS receiver (that is, every second). Then, the frame information d1 is encoded with the processing clock signal c2, and the encoded symbol signal d3 is transmitted to the receiving device 20 via the communication cable 51. The symbol signal d3 includes a reference clock signal c1 obtained by dividing the processing clock signal c2. Note that the symbol signal d3 is generated and transmitted even in a period during which the frame information d1 is not transmitted (an idle state 32 described later).

  The reception device 20 receives the symbol signal d3 including the frame information d1 as the symbol signal d3b at a time delayed by the signal delay time t1 from the transmission time of the symbol signal d3 in the transmission device 10. The signal delay time t1 varies depending on the length of the communication cable 51. The receiving device 20 extracts the reference clock signal c1 from the received symbol signal d3b. Then, from the reference clock signal c1, a processing clock signal c2 having the same frequency as the processing clock signal c2 of the transmission device 10 is generated, that is, restored. Further, the receiving device 20 returns the received symbol signal d3b and transmits it to the transmitting device 10 via the communication cable 51.

  The transmission apparatus 10 receives the symbol signal d3b returned from the reception apparatus 20 as the symbol signal d3c, and delays the transmission from the transmission apparatus 10 to the reception apparatus 20 based on the time difference between the symbol signal d3 and the symbol signal d3c. A signal delay time t1 which is time is acquired. Then, the transmission device 10 calculates the delay time t2 based on the signal delay time t1, and at the time of transmitting the next frame information d1, the time information d0 and the delay time designation information including the delay time t2 are used as the symbol signal d3. Transmit to the receiving device 20. Based on the delay time t2 indicated by the received delay time designation information, the receiving device 20 generates a correct second timing signal s0c having the same timing as the next correct second signal, and uses the correct second timing signal s0c to generate the time information d0 as a clock circuit. Set to 25. Thus, the clock circuit 25 outputs accurate time information.

Next, the configuration of the transmission device 10 will be described.
The transmission apparatus 10 includes a transmission frame generator 11, a parallel / serial converter 12, a transmission controller 13, a symbol encoder 14, a delay time measuring device 15, a phase synchronization circuit 16, and a calculation unit 17. Configured to include.

  The phase synchronization circuit 16 is a PLL (Phase Locked Loop) circuit using the precision clock signal c0 as a reference, and multiplies the precision clock signal c0 received from the GPS receiver to synchronize with the precision clock signal c0. Is used in the phase synchronization circuit 16 and is output to all the configurations of the transmission apparatus 10 excluding the phase synchronization circuit 16 (the above configurations 11 to 15, 17). That is, the phase synchronization circuit 16 is a processing clock signal generation unit that generates a processing clock signal c <b> 2 used for processing in the transmission device 10. In the example of the first embodiment, the frequency of the precision clock signal c0 is 10 MHz, and the frequency of the processing clock signal c2 is 32.768 MHz.

  The transmission frame generator 11 generates a transmission frame d1 including time information d0 received from the GPS receiver and delay time designation information indicating the delay time t2, and outputs the transmission frame d1 to the parallel / serial converter 12. The transmission frame d1 has the same configuration as the transmission frame d2 (serial transmission data) shown in FIG. 3, and in this embodiment, includes a synchronization pattern 33 (32 bits) that is a pattern for performing frame synchronization and time information d0. Time information 34 (56 bits), and other information 35 (128 bits) including delay time designation information including delay time t2. The configuration and the number of bits of the transmission frame d2 are not limited to the above, and can be changed as appropriate.

  The parallel / serial converter 12 loads the transmission frame d1 from the transmission frame generator 11 with the transmission start signal s1 from the transmission controller 13, converts the transmission frame d1 from parallel data to serial data, and transmits the transmission controller d1. 13 is output as serial transmission data d2 in synchronization with the symbol timing signal s2 from 13.

  The parallel / serial converter 12 receives a logical value 1, and after all the loaded frame information d1 is output, the logical value 1 is output.

  The transmission controller 13 generates a transmission start signal s1 and a symbol timing signal s2 synchronized with the true second signal s0 based on the true second signal s0 received from the GPS receiver, and serial transmission from the parallel / serial converter 12 Output control of the data d2 is performed. That is, the serial transmission data d2 is started to be transmitted by the transmission start signal s1, and is output bit by bit by the symbol timing signal s2.

  The transmission start signal s1 is output as a pulse after time t0 from the head (falling) of the second signal s0 (see FIG. 2). This transmission start time t0 is the time from when the second-second signal s0 is received to when the time information is started to be transmitted from the transmission device 10, and the transmission start time t0, the signal delay time t1, and the time information are completely transmitted. The required time t6 (specifically, the time until the time information received by the receiving device 20 is input to the clock circuit 25 of the receiving device 20) falls within 1 second (that is, the period of the second signal s0). It can be set arbitrarily within the range. The transmission controller 13 calculates a transmission start time t0 by counting a predetermined number of processing clock signals c2 from the head of the second signal s0. One symbol timing signal s2 is output per symbol (that is, one bit of transmission data).

  As shown in FIG. 3, the symbol encoder 14 encodes the serial transmission data d2 using the processing clock signal c2 in synchronization with the symbol timing signal s2, generates a symbol signal d3, and delays with the receiving device 20 Output to the time measuring device 15. As described above, the symbol signal d3 includes the reference clock signal c1.

  The reference clock signal c1 is a clock signal for generating (restoring) the processing clock signal c2 in the receiving device 20. In the example of FIG. 3, the frequency of the reference clock signal c1 is 512 kHz which is 1/64 of the processing clock signal c2.

  Details of the symbol signal d3 are shown in 41a, 42a and 43a in FIG. FIG. 3A shows a case where there is transmission data (that is, a case where transmission data generated by the transmission frame generator 11 is output from the parallel / serial converter 12), and FIG. The case where there is no data (that is, the case where the logical value 1 is output from the parallel / serial converter 12) is shown. The example of FIG. 3A shows one bit of data constituting the synchronization pattern 33.

  In the symbol signal d3, as shown by 41a in FIG. Cell 1 is for transmission of serial transmission data d2, cell 3 is for transmission of reference clock signal c1, and cells 2 and 4 are guard times for reference clock signal c1.

  In the cell 1, 1-bit data of the serial transmission data d2 is superimposed. In FIG. 3, 42 a is a case where the 1-bit data is 1, and 43 a is a case where the 1-bit data is 0. Thus, the cell 1 changes according to the serial transmission data d2. On the other hand, the cells 2 to 4 do not change according to the serial transmission data d2, and periodically repeat 1 and 0. This period is the length of 16 clocks of the processing clock signal c2. That is, 36 and 37 shown in 42a are the lengths of 8 clocks of the processing clock signal c2.

  Generating frame information including a synchronization pattern, time information, and delay time designation information so as to include a transmission frame generator 11, a parallel / serial converter 12, a transmission controller 13, and a symbol encoder 14; A frame information transmission unit that encodes using the processing clock signal c2 and transmits it as an information signal including the frame information and the reference clock signal c1 is configured.

  The delay time measuring device 15 measures a round trip time until the symbol signal d3 output from the transmission device 10 is turned back by the reception device 20 and returned to the transmission device 10. Then, based on this measurement time, a delay time until the signal output from the transmission device 10 reaches the reception device 20, that is, a signal delay that is a signal delay time by a transmission path between the transmission device 10 and the reception device 20. Time t1 is acquired. For example, the signal delay time t1 is obtained by equally dividing the measurement time (round trip time). As described above, the delay time measuring device 15 is a delay time acquisition unit that measures and acquires the signal delay time t <b> 1 through the transmission path between the transmission device 10 and the reception device 20.

  Specifically, the delay time measuring device 15 includes a configuration necessary as a receiving circuit such as a symbol decoder 21, a serial / parallel converter 22, a reception controller 23, and the like of the receiving device 20. Is compared with the synchronization pattern 33 of the symbol signal d3 outputted from the receiver 20 and the synchronization pattern 33 of the symbol signal d3c returned by the receiving device 20 to obtain the measurement time.

  The computing unit 17 calculates the delay time t2 using the signal delay time t1, and generates delay time designation information including the delay time t2. This delay time designation information is information used by the receiving device 20 to generate the second-second timing signal s0c. Details of the delay time t2 will be described later. Note that the signal delay time t <b> 1 may be acquired by the calculation unit 17 based on the measurement time (round trip time) measured by the delay time measuring device 15.

Next, the configuration of the receiving device 20 will be described.
The reception device 20 is configured to include a symbol decoder 21, a serial / parallel converter 22, a reception controller 23, an AND gate 24, a clock circuit 25, a delay device 26, and a phase synchronization circuit 27. Is done.

  The symbol decoder 21 decodes the serial symbol signal d3b output from the transmission apparatus 10, and generates serial transmission data d2b, a data acquisition timing signal s3, and a reference clock extraction signal s4. The content of the serial transmission data d2b corresponds to the content of the serial transmission data d2 in the transmission device 10. The data take-in timing signal s3 is generated once for each bit of the serial transmission data d2b and indicates the timing at which the transmission data is taken from the serial transmission data d2b. The reference clock extraction signal s4 is generated once for each bit of the serial transmission data d2b and is a signal for extracting the reference clock signal c1 (see FIG. 3).

  Specifically, as shown in FIG. 3, the symbol decoder 21 pays attention to changing only the cell 1 on which the serial transmission data d2 is superposed among the cells 1 to 4 of the received symbol signal d3b. Cell 1, cell 2, cell 3, and cell 4 are identified. Then, serial transmission data d2b is generated from the cell 1, and a data capture timing signal s3 is generated at a predetermined time position (timing) in the cell 1. In the example of FIG. 3, the data capture timing signal s3 is generated at approximately 3/4 timing in the cell 1.

  The symbol decoder 21 generates a reference clock extraction signal s4 for generating a reference clock signal c1 at a predetermined time position (timing) from the cell 2 to the cell 3. In the example of FIG. 3, the reference clock extraction signal s <b> 4 is generated from about 3/4 time position in the cell 2 to about 3/4 time position in the cell 3.

  The reception controller 23 samples the serial transmission data d2b based on the data fetch timing signal s3 from the symbol decoder 21, and searches for a synchronization pattern 33 (see FIG. 3) for achieving frame synchronization. When the synchronization pattern 33 is detected (that is, immediately after the synchronization pattern 33 is detected), the synchronization timing signal s0b is generated and output to the delay unit 26 (see FIG. 2).

  Further, when the reception controller 23 detects the synchronization pattern 33, the reception controller 23 generates and outputs a serial / parallel conversion period signal s5 having a predetermined length. The serial / parallel conversion period signal s5 indicates a period during which the serial / parallel converter 22 extracts the frame information d1b from the serial transmission data d2b. This period is a period having a length obtained by removing the synchronization pattern 33 from the serial transmission data d2b.

  The serial / parallel converter 22 captures the serial transmission data d2b from the symbol decoder 21 bit by bit using the data capture timing signal s3 during the serial / parallel conversion period signal s5. After capturing, serial transmission data d2b is converted from serial data to parallel data, and frame information d1b is generated and held. The content of the frame information d1b is the same as the content of the frame information d1 in the transmission device 10 except that the synchronization pattern 33 is missing.

In this way, the serial / parallel converter 22 outputs the frame information d1b including the time information d0b to the clock circuit 25. The time information d0b is included in the time information 34 shown in FIG.
Further, the serial / parallel converter 22 acquires the delay time t2 from the delay time designation information in the frame information d1b (specifically, other information 35), and outputs the delay time t2. The frame information d1b may be output from the serial / parallel converter 22 to the delay unit 26, and the delay unit 26 may acquire the delay time t2 from the frame information d1b.
As described above, the serial / parallel converter 22 holds the restored frame information d1b, extracts the time information and the delay time t2 from the restored frame information d1b, and outputs them.

  The delay unit 26 is based on the synchronization timing signal s0b from the reception controller 23 and the delay time t2 from the serial / parallel converter 22, and is set to the same second timing as the second signal s0 from the GPS receiver. A signal s0c is generated and output to the clock circuit 25. In the present embodiment, the delay unit 26 outputs the correct second timing signal s0c after the delay time t2 from the synchronization timing signal s0b.

  In the present embodiment, the transmission device 10 generates the delay time t2, and the reception device 20 outputs the true second timing signal s0c after the delay time t2 from the synchronization timing signal s0b. It may be configured. That is, a delay time t4 (for example, t4 = t2−t5) is generated in the transmission device 10 using the time t5 that is known in the transmission device 10 and the reception device 20, and the synchronization timing signal s0b and the delay time are generated in the reception device 20. The true second timing signal s0c may be output based on t4, that is, the true second timing signal s0c may be output after a delay time (t4 + t5) from the synchronization timing signal s0b.

  The clock circuit 25 outputs time information d0b every moment. In this example, since the clock circuit 25 is operated by the processing clock signal c2, the time information d0b is output about every 30 (nsec). Then, the clock circuit 25 sets the time information d0 included in the frame information d1b by using the correct second timing signal s0c. Thereby, the clock circuit 25 can output an accurate time as the time information d0b. This time information d0b is used as a time stamp for the observation data in the observation apparatus.

  The true second timing signal s0c is taken out based on the synchronization timing signal s0b and the delay time t2 so as to include the delay device 26 and the clock circuit 25, and at the true second timing s0c, that is, the delay time t2 from the synchronization timing signal s0b. At the timing when the time elapses, the time information is set in the timepiece circuit 25, and the timepiece unit is configured to output accurate real time information d0b from the timepiece circuit 25.

  The AND gate 24 takes out the reference clock signal c1 by ANDing the symbol signal d3b and the reference clock extraction signal s4 from the symbol decoder 21. Thus, since the reference clock signal c1 is extracted by the gate only without being sampled by the clock signal of the receiving device 20, the reference clock signal c1 can be a stable clock free of jitter, and can be extended. In this case, a stable processing clock signal c2 having a frequency deviation equivalent to that of the precision clock signal c0 and having little jitter can be generated.

  The phase synchronization circuit 27 is a PLL circuit that uses the reference clock signal c1 as a reference, and generates a processing clock signal c2 that is synchronized with the reference clock signal c1 by multiplying the frequency of the reference clock signal c1 to achieve phase synchronization. In addition to being used in the circuit 27, the signal is output to all the configurations of the receiving device 20 excluding the phase synchronization circuit 27 (the above configurations 21 to 26). The frequency of the processing clock signal c2 is the same as the processing clock signal c2 of the transmission apparatus 10, and is 32.768 MHz.

  The synchronization timing signal s0b is obtained from the frame information received from the transmission apparatus 10 so as to include a symbol decoder 21, a serial / parallel converter 22, a reception controller 23, an AND gate 24, and a phase synchronization circuit 27. At the same time, the time information d0 and the delay time designation information t2 from the transmission device 10 are restored, the reference clock signal c1 is extracted from the information signal received from the transmission device 10, and the processing clock signal c2 is obtained based on the reference clock signal c1. A decoding unit to be restored is configured. The synchronization timing signal s0b is a reference timing signal that serves as a reference for taking out the true second timing signal s0c having the same timing as that of the true second signal s0.

Next, details of the operation of the time information transmission system will be described with reference to FIG. In order to facilitate understanding of FIG. 2, the temporal relationship of each signal in FIG. 2 is schematically shown rather than strict.
As illustrated in FIG. 2, the transmission device 10 receives time information d0 and a second signal s0 from the GPS receiver every second. The time information d0 indicates the time at the timing indicated by the next received second signal s0. That is, the second signal s0 indicates the actual timing of the time indicated by the time information d0 received before the second signal s0.

  In the example of FIG. 2, the falling edge of the second signal s0 (2) indicates the actual timing of the time indicated by the time information d0 (1). For example, when the time information d0 (1) is 15:45:30, the second signal s0 (2) is received at 15:45:30.

  Further, the transmission device 10 continuously receives the precision clock signal c0 synchronized with the second signal s0 from the GPS receiver. The precision clock signal c0 is received from the GPS receiver in this example, but is not necessarily received from the GPS receiver. For example, the precision clock signal c0 is configured to be generated by the transmission device 10 using a thermostat type oscillator. May be.

  In the transmission device 10, the transmission frame generator 11 generates a transmission frame d1 (1) including the received time information d0 (1). As described above, the transmission frame d1 (1) includes the synchronization pattern 33, time information 34, and other information 35 (see FIG. 3). The time information d0 (1) is included in the time information 34.

  Next, after the transmission start time t0 from the head (falling) of the positive second signal s0 (1), the parallel / serial converter 12 converts the transmission frame d1 (1) by the transmission start signal s1 from the transmission controller 13. Load and convert to serial data. The serial data is output as serial transmission data d2 (31 in FIG. 2). At this time, the serial transmission data d2 is output bit by bit in synchronization with the symbol timing signal s2 from the transmission controller 13. After all the serial transmission data d2 is output, as described above, the logical value 1 is output from the parallel / serial converter 12, and the idle state (32 in FIG. 2) in which no data transmission is performed is entered.

  The serial transmission data d2 is encoded by the symbol encoder 14 using the processing clock signal c2, and is output as the symbol signal d3. At this time, the serial transmission data d2 is output bit by bit for each symbol timing signal s2. As described above, the symbol signal d3 includes the reference clock signal c1.

  The symbol signal d3 is transmitted via the communication cable 51 and is received by the receiving device 20 as the symbol signal d3b. The symbol signal d3b is returned from the receiving device 20, and is received by the delay time measuring device 15 of the transmitting device 10 as the symbol signal d3c. The delay time measuring device 15 acquires a signal delay time t1 for transmission from the transmission device 10 to the reception device 20 based on the time difference between the symbol signal d3 transmitted from the transmission device 10 and the symbol signal d3c.

  Based on the signal delay time t1, the calculation unit 17 calculates the delay time t2, and generates delay time designation information including the delay time t2. The delay time designation information including the delay time t2 is included in the frame information d1 (2) and transmitted to the receiving device 20 after the next time information d0 (2) is received.

The calculation method of the delay time t2 is as follows.
The transmission apparatus 10 calculates the delay time t2 as follows using the signal delay time t1, the transmission start time t0, and the synchronization pattern detection time t3 acquired by the delay time measuring device 15. The calculation of t2 is performed using, for example, a microcomputer.
t2 (seconds) = 1 (seconds)-(t0 + t1 + t3)

  Here, the transmission start time t0 is a time from the reception timing of the second signal s0 from the GPS receiver to the start of transmission of the frame information d1 as the serial transmission data d2. The synchronization pattern detection time t3 is a synchronization pattern detection time (time required for detection of the synchronization pattern) in the reception controller 23, and is determined from the number of bits of the synchronization pattern.

  The symbol signal d3b received by the receiving device 20 is decoded by the symbol decoder 21, and as shown in FIG. 3, serial transmission data d2b, a data acquisition timing signal s3, and a reference clock extraction signal s4 (in FIG. 3). 44a) is generated. As described above, the data capture timing signal s3 indicates the timing for capturing data from the transmission data d2b. The reference clock extraction signal s4 is a signal for extracting the reference clock signal c1.

  Next, the reception controller 23 detects the synchronization pattern 33 after the idle state 32 is detected. At this time, the synchronization pattern 33 in the serial transmission data d2b is detected after the synchronization pattern detection time t3 from the head detection of the transmission data d2b, and immediately after the synchronization pattern 33 is detected, the synchronization timing signal s0b and the serial / parallel conversion period signal are detected. s5 is generated.

  Next, in the serial / parallel converter 22, frame information d 1 b is generated from the serial transmission data d 2 b during the serial / parallel conversion period signal s 5 and is output to the clock circuit 25. This frame information d1b includes time information d0 (1). Further, the serial / parallel converter 22 extracts the delay time t2 from the frame information d1b and outputs it to the delay unit 26.

  Then, in the delay unit 26, the second-second timing signal s0c is generated after the delay time t2 from the synchronization timing signal s0b.

  As described above, the true-second timing signal s0c is a signal that matches the same timing as the true-second signal s0 (2) from the GPS receiver. Then, in the clock circuit 25, time information d0 (1) included in the frame information d1b is set by the second seconds timing signal s0c. Thereby, the time information d0b indicating the accurate time is output from the clock circuit 25.

  Further, in the AND gate 24, as shown in FIG. 3, the reference clock signal c1 (45a in FIG. 3) is generated by the symbol signal d3b (42a and 43a in FIG. 3) and the reference clock extraction signal s4 (44a in FIG. 3). Is taken out. Then, in the phase synchronization circuit 27, a processing clock signal c2 is generated based on the reference clock signal c1.

  In the above-described embodiment, the transmission device 10 is configured to periodically receive the time information d0 and the second signal s0 from the GPS receiver. However, the present invention is not limited to this. The time information d0 and the second signal s0 may be periodically received from outside the GPS receiver.

  In the above-described embodiment, each time information is transmitted from the transmission device 10 to the reception device 20 (that is, every second), the signal delay time t1 is obtained and the delay time t2 is recalculated. However, the present invention is not limited to this. For example, the delay time t2 acquired at the first time information transmission may be used not only at the second time information transmission but also at the third and subsequent time information transmissions.

  In the above-described embodiment, the receiving device 20 detects the synchronization pattern 33 from the received frame information, and after the synchronization pattern detection time t3 from the detection of the head of the frame information, the second of the same timing as the timing of the second signal s0. Although the configuration is such that the reference synchronization timing signal d0b for extracting the timing signal s0c is extracted, the present invention is not limited to this, and the reference timing signal is extracted at a timing other than the synchronization timing signal d0b. May be. For example, the reference timing signal may be extracted at the timing when reception of the frame information is completed. In this case, the delay time t2 uses the reception period T of the time information d0, the transmission start time t0, the signal delay time t1, and the time t3 (that is, the number of bits of frame information) until the reference timing is extracted. Will be calculated. For example, it is calculated by t2 = T− (t0 + t1 + t3).

  In the above-described embodiment, the time information and the reference clock signal are transmitted from the transmission device 10 to the reception device 20, but the present invention is not limited to this. For example, the present invention can be applied to the case where only the time information is transmitted without transmitting the reference clock signal, or the case where only the reference clock signal is transmitted without transmitting the time information.

According to the first embodiment, at least the following effects can be obtained.
(A1) The time information is received from the outside at a predetermined cycle T, the second signal indicating the actual timing indicated by the time information is received at the cycle T later than the time information, and the information signal including the time information is cycled. In a time information transmission system including a transmission device that transmits at T and a reception device that receives an information signal from a transmission device via a transmission line, the transmission device acquires a signal delay time t1 through the transmission line, and a signal delay time The delay time t2 is calculated using t1, delay time designation information including the delay time t2 is generated, frame information including time information and delay time designation information is generated and transmitted, and the reception device From the received frame information, the reference timing for extracting the correct second timing that is the same as the correct second signal timing is extracted, and the time information and the delay time designation information are recovered. Since the time is set to the clock circuit based on the reference timing and the delay time t2, the time information is set in the clock circuit at the time of the second, and the real time information is output from the clock circuit. The time information and the second signal from the machine can be sent to the observation point with a small error (for example, an error of several tens of nanoseconds), and the time accuracy and real-time property can be improved.
(A2) The transmission device generates a processing clock signal, encodes frame information using the processing clock signal, transmits the information as an information signal including time information, delay time designation information, and a reference clock signal, and receives it. Since the apparatus is configured to extract the reference clock signal from the received information signal and restore the processing clock signal based on the reference clock signal, the processing clock signal generated by the transmitting apparatus can be restored on the receiving apparatus side. it can. Therefore, it is possible to easily obtain a power-saving and highly accurate processing clock signal on the receiving side.
(A3) The transmitting device transmits the first information signal to the receiving device, receives the first information signal returned from the receiving device, acquires the signal delay time t1, and specifies the time information and the delay time. Frame information including the information is generated and transmitted to the transmission device as a second information signal, and the reception device receives the second information signal, extracts the reference timing, and also includes time information and delay time designation information. And is configured to take out the true second timing based on the reference timing and the delay time t2, and sending the time information and the true second signal from the outside (for example, GPS receiver) to the observation point with a small error, It can be easily realized.
(A4) The time from when the receiving device starts receiving frame information to taking out the reference timing is t3, and the time from when the transmitting device receives the second signal from the outside to when it starts transmitting frame information is t0. In this case, since the delay time t2 is calculated using the periods T and t0 and the signal delay times t1 and t3, the delay time t2 can be easily calculated.
(A5) Since the delay time t2 is recalculated every time time information is transmitted from the transmission device to the reception device, the transmission signal delay time t1 from the transmission device to the reception device changes (for example, Even when the length of the communication cable 51 fluctuates due to seawater temperature, tidal current, or the like, or when the stray capacitance of the communication cable 51 fluctuates), accurate time information can be generated in the receiving device. .
(A6) Since the time information from the GPS receiver, the second signal from the GPS receiver, and the reference clock generated from the precise clock of the GPS receiver are configured to be transmitted through a single signal line, The transmission cable can be simplified.
(A7) Since the reference clock signal c1 is taken out only by the gate without being sampled by the clock signal of the receiving device 20, the reference clock signal c1 can be a stable clock without jitter, and extended. Can generate a stable processing clock signal c2 having a frequency deviation equivalent to that of the precision clock signal c0 and little jitter.
(A8) The transmission device generates frame information including a synchronization pattern, time information, and delay time designation information, and the reception device uses the synchronization timing when the synchronization pattern is detected from the frame information received from the transmission device as a reference. Since the time information is set in the clock circuit at the right second timing based on the synchronization timing and the delay time t2, the reference timing can be easily extracted.

(Second Embodiment)
A time information transmission system according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a diagram showing a configuration of a time information transmission system according to the second embodiment of the present invention, which is an example in which the present invention is applied to a submarine earthquake observation system. 4, components that perform the same operations as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted. The operation timing in the first embodiment shown in FIGS. 2 and 3 is the same in the second embodiment. That is, FIG. 2 and FIG. 3 are also diagrams showing the operation timing according to the second embodiment.

  In the time information transmission system according to the second embodiment, a land device 110 as a transmission device is signal-connected to a plurality of observation devices 120 as reception devices in a form that depends on an optical fiber (optical communication cable) 151. That is, the land device 110 is connected to the first-stage observation device 120 (1) by the first-stage optical fiber 151 (1), and the observation device 120 (1) is connected to the second-stage optical fiber 151 (2) by the second-stage optical fiber 151 (2). The (n-1) th stage observation device 120 (n-1) is connected to the nth stage observation device 120 (n) by the nth stage optical fiber 151 (n). )It is connected to the.

  When the delay time t2 is not set correctly in each observation device 120, for example, immediately after each observation device 120 is installed, the land device 110 sequentially delivers a signal to each observation device 120, and each observation device 120 After obtaining the signal delay time t1 in the device 120, the delay time t2 is calculated based on the signal delay time t1, and the delay time designation information including the delay time t2 is distributed to each observation device 120. Each observation device 120 holds the received delay time t2, and uses the time information d0 and the delay time t2 received from the land device 110 to adjust its own clock information d0b to the correct time. At this time, as in the first embodiment, the time information d0 received from the land device 110 is distributed at a timing earlier than the actual time. That is, it is delivered at the timing shown in FIG.

  For example, the land device 110 distributes a signal to the first-stage observation device 120 (1) and acquires the signal delay time t1 (1) in the observation device 120 (1), and then the delay time t2 (1). And delay time designation information including the delay time t2 (1) is distributed to the observation device 120 (1). The observation device 120 (1) holds the received delay time t 2 (1), and uses the time information d 0 and the delay time t 2 (1) received from the land device 110 to obtain its own clock information d 0 b at an accurate time. To match.

  Next, the land device 110 delivers a signal to the second-stage observation device 120 (2) via the observation device 120 (1), and acquires the signal delay time t1 (2) in the observation device 120 (2). After performing the above, a delay time t2 (2) is calculated. Then, the delay time designation information including the delay time t2 (2) is distributed to the observation device 120 (2) via the observation device 120 (1). The observation device 120 (2) holds the received delay time t2 (2), and uses the time information d0 and the delay time t2 (2) received from the land device 110 via the observation device 120 (1), The own clock information d0b is set to an accurate time.

The configuration of the land device 110 will be described.
The land device 110 includes a transmission frame generator 111, a parallel / serial converter 12, a transmission controller 13, a symbol encoder 14, a delay time measuring device 15, a phase synchronization circuit 16, a calculation unit 17, And an electric / optical converter 117. The difference from the configuration of FIG. 1 is a transmission frame generator 111 and an electrical / optical converter 117, and the other configurations are the same as those of FIG.

  In the land device 110, the processing clock signal c2 generated by the phase synchronization circuit 16 is used in the phase synchronization circuit 16, and the configuration of the land device 110 is excluded except for the phase synchronization circuit 16 and the electrical / optical converter 117. Output to all.

  The transmission frame generator 111 generates a transmission frame d 1 and outputs it to the parallel / serial converter 12. Similar to the first embodiment, the transmission frame d1 has the same configuration as the transmission frame d2 (serial transmission data) shown in FIG. 3, and includes a synchronization pattern 33, time information 34, and other information 35. The time information 34 includes time information d0 received from the GPS receiver. The other information 35 includes delay time designation information including the delay time t2, setting request information d01, observation device designation information d02, and loopback designation information d03. The setting request information d01, the observation device designation information d02, and the loopback designation information d03 are input by an operator from an operation input unit (not shown) of the land device 110, for example.

The observation device designation information d02 is information for the land device 110 to designate the observation device 120 that is the information transmission partner, and for example, the device number of the observation device 120 is used.
The setting request information d01 is information for requesting the observation device 120 to receive the information transmitted from the land device 110 as reception information of the observation device 120 specified by the observation device specification information d02. It is represented by 1 (valid: setting requested) or 0 (invalid: no setting requested).

  The return specification information d03 is information for specifying the observation device 120 specified by the observation device specification information d02 to return the information transmitted from the land device 110. For example, 1 (valid: with return specification) Or 0 (invalid: no wrapping specified).

  The electrical / optical converter 117 converts the electrical signal generated by the land device 110 into an optical signal and outputs the optical signal to the observation device 120 (1). Further, the optical signal received from the observation device 120 (1) is converted into an electric signal. The electrical / optical converter 117 is a single-core bidirectional electrical / optical conversion capable of transmitting the optical signal output and the optical signal received from the observation device 120 (1) through the single-core optical fiber 151 (1). It is a vessel.

  Instead of using the electrical / optical converter 117 and the optical fiber 151 (1), it is possible to use a communication cable 51 capable of bidirectional communication as in FIG.

Next, the configuration of the observation apparatus 120 will be described.
The observation device 120 includes a symbol decoder 21, a serial / parallel converter 122, a reception controller 23, an AND gate 24, a clock circuit 25, a delay circuit 26, a phase synchronization circuit 27, and an electrical / optical conversion. Devices 127 and 128 and a switch 129. 1 differs from the configuration of FIG. 1 in a serial / parallel converter 122, electrical / optical converters 127 and 128, and a switch 129, and other configurations are the same as those in FIG.

  In the observation device 120, the processing clock signal c <b> 2 generated by the phase synchronization circuit 27 is used by the phase synchronization circuit 27, and except for the phase synchronization circuit 27 and the electrical / optical converters 127 and 128, Output to all of the configurations.

  The electric / optical converter 127 converts the electric signal generated by the observation device 120 into an optical signal and outputs the optical signal to the land device 110 or the upper observation device 120. Moreover, the optical signal received from the land apparatus 110 or the upper observation apparatus 120 is converted into an electric signal. The higher-order observation device 120 is an observation device 120 that is closer to the land device 110 than the observation device 120 in the connection of the type to be determined. The electrical / optical converter 127 is a single-core bidirectional electrical / optical converter capable of transmitting the optical signal output and the optical signal received from the land device 110 through the single-core optical fiber 151.

  The electrical / optical converter 128 converts the electrical signal generated by the observation device 120 (1) into an optical signal and outputs the optical signal to the next-stage (lower) observation device 120 (2). Moreover, the optical signal received from the observation apparatus 120 (2) is converted into an electric signal. In the final stage observation device 120 (n), the electrical / optical converter 128 may be omitted.

  The serial / parallel converter 122 captures the serial transmission data d2b from the symbol decoder 21 bit by bit using the data capture timing signal s3 during the serial / parallel conversion period signal s5. After capturing, serial transmission data d2b is converted from serial data to parallel data, and frame information d1b is generated and held. The content of the frame information d1b is the same as the content of the frame information d1 in the land device 110 except that the frame synchronization pattern 33 is missing.

  Specifically, the serial / parallel converter 122 includes a shift register and a holding register HR that holds the value of the shift register, and the serial transmission data d2b is converted into the shift register by the data fetch timing signal s3. 1 bit at a time. After the final data in the period indicated by the serial / parallel conversion period signal s5 is input to the shift register, the serial / parallel converter 122 outputs the data in the shift register as the received frame information d1b. .

In this way, the serial / parallel converter 122 outputs the frame information d1b including the time information d0b to the clock circuit 25. The time information d0b is included in the time information 34 shown in FIG.
Further, the serial / parallel converter 122 determines whether or not the observation device designation information d02 in the shift register satisfies the condition C that the observation device 120 (1) is the device number and the setting request information d01 is valid. When the condition C is satisfied, the data in the shift register is written to the holding register HR, the delay time t2 is obtained from the holding register HR (specifically, the other information 35), and the delay time is supplied to the delay unit 26. Output.

  Further, the serial / parallel converter 122 obtains the folding designation information d03 from the holding register HR (specifically, other information 35), and sends a control signal for setting the observation device 120 to the folded state or the non-folded state. , Output to the switch 129. The contents of the holding register HR are held until the serial transmission data d2b input to the serial / parallel converter 122 next satisfies the above condition C.

  Thus, when the condition C is satisfied, the serial / parallel converter 122 controls the state of the return switch 129 based on the return specification information d03 in the data held in the holding register HR. That is, the serial / parallel converter 122 controls the switch 129 to be in the folded state when the folding designation information d03 is valid, and causes the switch 129 to be in the non-folded state when the folding designation information d03 is invalid. Control.

  The switch 129 switches the observation device 120 between a folded state and a non-folded state. The folded state is a state in which a signal is transmitted from the land device 110, folded back by the observation device 120, and returned to the land device 110. The non-wrapped state is a state that is not a folded state. In an initial state such as when the power is turned on, the switch 129 is set so that the observation device 120 is in a non-folded state.

  The switch 129 converts the symbol signal d3b, which is an electrical signal from the electrical / optical converter 127, into the electrical / optical converter 127 in accordance with the control signal from the serial / parallel converter 122 when the folding designation information d03 is designated to be folded. Turn back to. That is, the contact b of the switch 129 and the electric signal input c of the electric / optical converter 127 are connected.

  Further, the switch 129 outputs the electrical signal from the electrical / optical converter 128 to the electrical / optical converter 127 according to the control signal from the serial / parallel converter 122 when the folding designation information d03 is designated as non-wrapping. . That is, the contact a of the switch 129 and the electrical signal input c of the electrical / optical converter 127 are connected.

  Next, setting of the delay time t2 (1) to the delay device 26 in the observation device 120 (1), generation of the time information d0b, the positive second timing signal s0c, and the processing clock signal c2 in the observation device 120 (1). Will be described with reference to FIG.

  First, after receiving the second signal s0 (1) and the time information d0 (1) from the GPS receiver, the land device 110 receives the observation device designation information d02 from the observation device 120 (1) in the transmission frame generator 111. The frame number d1 (1) is generated by setting the device number, validating the turn-back designation information d03, and validating the setting request information d01. The frame information d1 (1) includes time information d0 (1) from the GPS receiver.

  The frame information d1 (1) is output as a symbol signal d3 from the symbol encoder 14 through the parallel / serial converter 12 in accordance with a control signal from the transmission controller 13. The symbol signal d3 is converted into an optical signal by the electrical / optical converter 117 and output to the optical fiber 151 (1) which is a transmission path.

  As described in the first embodiment, the output start of the frame information from the symbol encoder 14 is controlled by the transmission controller 13 so as to be after the time t0 from the true second signal s0 of the GPS receiver ( (See FIG. 2).

  The observation device 120 (1) converts the optical signal from the land device 110 sent via the optical fiber 151 (1) into a symbol signal d 3 b that is an electric signal by the electric / optical converter 127. The electric signal d3b is converted again into an optical signal by the electric / optical converter 128 and relayed to the optical fiber 151 (2) as a transmission path for relaying to the next observation device 120 (2) connected in a wrinkle form. Is output. At this time, the observation device 120 (1) is in a non-turned state, and the contact point a of the switch 129 and the electric signal input c of the electric / optical converter 127 are connected.

  Similarly to the first embodiment, the symbol decoder 21 generates serial transmission data d2b, a data acquisition timing signal s3, and a reference clock extraction signal s4 that are received data from the symbol signal d3b.

The reception controller 23 detects the idle state using the reception data d2b and the data capture timing signal s3, as in the first embodiment. Then, after detecting the idle state, the synchronization pattern 33 of the reception data d2b is searched, and the serial / parallel conversion period signal s5 and the synchronization timing signal s0b are generated. In the present embodiment, the idle state is a case where 1 is continuous in a period of 32768 bits, assuming the maximum length of the reception data d2b, that is, the maximum length of the transmission frame, and is a transmission frame start pattern. The synchronization pattern 33 is set to (AAAAA09B7) ₁₆ having a large autocorrelation.

  As described above, the serial / parallel converter 122 outputs the frame information d1b including the time information d0 (1). Although the time information d0 (1) included in the frame information d1b is set in the clock circuit 25 by the correct second timing signal s0c, since the delay time t2 is not set correctly at this stage, the output of the correct second timing signal s0c is output. The timing is not correct, and therefore the time information d0b output from the clock circuit 25 is not correct.

  Further, the serial / parallel converter 122 determines whether or not the observation device designation information d02 in the reception data d2b satisfies the condition C that the device number of the observation device 120 (1) is valid and the setting request information d01 is valid. Determine. In this case, since the above condition C is satisfied, the loopback designation information d03 (valid) in the reception data d2b is held in the holding register HR, and the loopback switch 129 is looped back based on the loopback designation information d03 (valid). Control to be in a state. As a result, the contact b of the switch 129 and the electrical signal input c of the electrical / optical converter 127 are connected.

  Note that in the observation devices 120 (2) to 120 (n), similarly to the observation device 120 (1), the optical signal transmitted from the previous observation device 120 is converted into a symbol signal d3b which is an electrical signal. The electrical signal d3b is converted again into an optical signal and output to the optical fiber 151 for conversion and relaying to the next observation device 120. Then, as in the first embodiment, in each symbol decoder 21, serial transmission data d2b that is received data, a data capture timing signal s3, and a reference clock extraction signal s4 are generated from the symbol signal d3b. Further, the frame information d1b (1) is taken out in each serial / parallel converter 122 and set in each clock circuit 25 as time information d0 (1), but the delay time t2 is not set correctly. The time information d0b output from the clock circuit 25 is not correct.

  Next, after receiving the next true second signal s0 (2) and time information d0 (2), the land device 110 generates the next frame information d1 (2) in the transmission frame generator 111, and performs parallel / serial conversion. After being processed by the encoder 12 and the symbol encoder 14, it is output from the electrical / optical converter 117. In this frame information d1 (2), the observation device designation information d02 is the device number of the observation device 120 (1), but the setting request information d01 and the loopback designation information d03 are set to either valid or invalid. It doesn't matter. This frame information d1 (2) includes time information d0 (2) from the GPS receiver.

  Similarly to the time information d0 (1), this time information d0 (2) is set in the clock circuit 25 of each of the observation devices 120 (1) to 120 (n), but the delay time t2 is set correctly. Therefore, the time information d0b output by each clock circuit 25 is not correct.

  The land device 110 measures the round trip time from the observation device 120 (1) to the return time after the frame information d 1 (2) is transmitted, by the delay time measuring device 15. Then, similarly to the first embodiment, the delay to be transmitted to the observation device 120 (1) based on the signal delay time t1 (1) calculated from the round trip time, the transmission start time t0, and the synchronization pattern detection time t3. Time t2 (1) is calculated.

  The delay time designation information including the delay time t2 (1) is the next frame information d1 (3) generated by the frame generator 111 after receiving the next true second signal s0 (3) and the time information d0 (3). And output from the electrical / optical converter 117 after being processed by the parallel / serial converter 12 and the symbol encoder 14. In this frame information d1 (3), the observation device designation information d02 is the device number of the observation device 120 (1), the setting request information d01 is valid, and the return designation information d03 is invalid. The frame information d1 (3) includes time information d0 (3) from the GPS receiver.

  The frame information d1 (3) is transmitted to the observation device 120 (1), and the serial / parallel converter 122 outputs the frame information d1b including the time information d0 (3). Further, the serial / parallel converter 122 determines whether or not the observation device designation information d02 in the reception data d2b satisfies the condition C that the device number of the observation device 120 (1) is valid and the setting request information d01 is valid. Determine. In this case, since the condition C is satisfied, the delay time t2 in the reception data d2b is held in the holding register HR and output to the delay unit 26.

  Further, since the serial / parallel converter 122 satisfies the above condition C, the series / parallel converter 122 holds the loopback designation information d03 (invalid) in the reception data d2b in the holding register HR and also loops back by the loopback designation information d03 (invalid). The control switch 129 is controlled so as to be in a non-folded state.

  Then, similarly to the receiving device 20 of the first embodiment, the observation device 120 (1) uses the delay device 26 to delay the synchronization timing signal s0b for a preset delay time t2 (1). Thus, a second-second timing signal s0c having the same timing as the second-second signal s0 of the GPS receiver is generated. In addition, the observation device 120 (1) generates time information d0b that is the same as the GPS time by setting the frame information d1b in the clock circuit 25 in synchronization with the true second timing signal s0c.

  Similarly to the receiving device 20 of the first embodiment, the observation device 120 (1) generates the reference clock extraction signal s 4 from the information signal received from the land device 110 by the symbol decoder 21. Then, a reference clock c1 signal is generated from the symbol signal d3b and the reference clock extraction signal s4 by the AND gate 24, and a processing clock signal c2 is generated by the phase synchronization circuit 27.

  The time information d0 (3) is also set in each clock circuit 25 of the observation device 120 (2) to the observation device 120 (n), but is delayed in the observation device 120 (2) to the observation device 120 (n). Since the time t2 is not set correctly, the time information d0b output from each clock circuit 25 of the observation devices 120 (2) to 120 (n) is not correct.

  Next, setting of the delay time t2 (2) to the delay device 26 in the observation device 120 (2), generation of the time information d0b, the positive second timing signal s0c, and the processing clock signal c2 in the observation device 120 (2). Will be described.

  After the setting of the delay time t2 (1) to the observation device 120 (1) is completed, the land device 110 sets the observation device designation information d02 to the device number of the observation device 120 (2) in the transmission frame generator 111. Then, the return designation information d03 is validated, and the frame information d1 (4) in which the setting request information d01 is validated is generated. This frame information d1 (4) includes time information d0 (4) from the GPS receiver.

  The frame information d1 (4) is processed by the parallel / serial converter 12 and the symbol encoder 14 in accordance with a control signal from the transmission controller 13, and then converted into an optical signal by the electrical / optical converter 117. Is output to the optical fiber 151 (1), and then converted into an electric signal d3b by the electric / optical converter 127 in the observation device 120 (1), and further converted into an optical signal by the electric / optical converter 128, It is output to the optical fiber 151 (2).

  The optical signal output to the optical fiber 151 (2) is converted into a symbol signal d3b which is an electric signal by the electric / optical converter 127 in the observation device 120 (2). The electrical signal d3b is converted again into an optical signal by the electrical / optical converter 128 of the observation device 120 (2) for relaying to the next-stage observation device 120 (3) connected in a format. It is output to a certain optical fiber 151 (3).

  In this way, the observation device 120 (2) is set to the folded state by the frame information d1 (4) in the same manner as the setting process of the delay time t2 (1) to the delay device 26 in the observation device 120 (1) described above. Is done. Next, similarly to the processing in the frame information d1 (2), the land device 110 acquires the signal delay time t1 (2) from the frame information d1 (5), and delays using the signal delay time t1 (2). Time t2 (2) is calculated. Next, similarly to the processing in the frame information d1 (3), the delay time t2 (2) is set to the delay unit 26 in the observation device 120 (2) by the frame information d1 (6), and the time information d0 ( 6) is set in the clock circuit 25.

  In the observation device 120 (1) and each clock circuit 25 of the observation devices 120 (3) to 120 (n), the time information d0 is obtained from the frame information d1 (4) including the time information d0 (4). (4) is set, time information d0 (5) is set by frame information d1 (5) including time information d0 (5), and time is set by frame information d1 (6) including time information d0 (6). Information d0 (6) is set. At this time, since the accurate delay time t2 is set in the observation device 120 (1), the time information d0b output from the clock circuit 25 of the observation device 120 (1) is correct. However, since the accurate delay time t2 is not set in the observation devices 120 (3) to 120 (n), the time information d0b output from the clock circuit 25 is not correct.

  In this way, the same processing as that for setting the delay time t2 (1) to the delay device 26 in the observation device 120 (1) is performed on the observation device 120 (2) and later, so that the following equation is connected. For all the observation devices 120, a different delay time t2 is set for each observation device 120. Then, after the correct delay time t2 is set for all the observation devices 120, every time the frame information d1 is transmitted from the land device 110, the clock circuit 25 of all the observation devices 120 has the time information at the correct timing. d0 is set, and correct time information d0b is output. In the example of this embodiment, the transmission start time t0 is set to 998 (msec) in consideration of the total length of the observation system, the number of observation devices, and the transmission time of the transmission frame for time information.

  As described above, the transmission start time t0 is within a range in which the signal delay time t1 and the time t6 required to complete the transmission of time information are within one second (that is, the period of the second signal s0). Can be set arbitrarily. If t0 = 1− (t1 + t6) is set, t2 becomes a known fixed value (t2 = t6−t3), so there is no need to transmit delay time designation information including the delay time t2.

  However, when the plurality of observation devices 120 are connected to each other as in the present embodiment, the signal delay time t1 is different for each observation device 120. Therefore, in order to set t2 to a fixed value in each observation device 120, The transmission start time t0 in the land device 110 needs to be different for each observation device 120. Thus, if t2 is a fixed value in each observation device 120, the transmission start time t0 for each observation device 120 will be different, and the setting of the transmission start time t0 will be complicated and error-prone.

  On the other hand, in the present embodiment, the same transmission start time t0 is set for each observation device 120, and the delay time t2 can be set to a variation value in all of the plurality of observation devices 120. This simplifies setting of the transmission start time t0 in the land device 110 and improves usability. In addition, by setting the transmission start time t0 for each observation device 120 to be the same, each cycle and time information can be transmitted to each observation device 120 through a single signal line connected to the following equation.

  The generation of the time information d0b, the correct second timing signal s0c, and the processing clock signal c2 in the observation device 120 (2) is performed in the same manner as the observation device 120 (1). In addition, regarding the setting of the delay time t2 to the delay device 26 after the observation device 120 (3), the generation of the time information d0b, the right second timing signal s0c, and the processing clock signal c2 after the observation device 120 (3), This is performed in the same manner as the observation device 120 (2).

  In this embodiment, the delay control of the delay unit 26 is performed by the processing clock signal c2 generated by the phase synchronization circuit 27. Since the frequency of the processing clock signal c2 is 32.768 MHz, the time information d0b is It is possible to adjust the time at the GPS receiver with an accuracy of ± 50 nsec.

  In the above description, the setting request information d01 is always valid in the observation device 120 designated by the observation device designation information d02. Therefore, in the observation device 120 specified by the observation device designation information d02, the setting request information d01 from the land device 110 can be omitted by setting the same state as when the setting request information d01 is valid. .

  In the above description, the delay time t2 is set in order from the observation device 120 (1) close to the land device 110. Conversely, in other words, the delay time is set in order from the observation device 120 (n) farthest from the land device 110. The time t2 may be set.

  In the above description, the correct delay time t2 is sequentially set for all the observation devices 120. However, the correct delay time t2 is set only for some of the observation devices 120 as necessary. It is also possible. At this time, even when the delay time t2 is set for some of the observation devices 120, the other observation devices 120 can receive the time information transmitted from the land device 110, and therefore output from the clock circuit 25. The accuracy of the time information to be performed can be increased.

According to the second embodiment, at least the following effects can be obtained.
(B1) Since the plurality of observation devices 120 are connected in a format that determines the time, the time information d0b, the second timing signal s0c, and the processing clock signal c2 in the plurality of observation devices 120 are converted into the time information d0 in the GPS receiver, It can be easily realized that the accuracy is close to the second signal s0 and the precision clock signal c0.
(B2) The observation device is set in the folded state by the first transmission frame, the signal delay time t1 is acquired by the second transmission frame, and the delay time t2 is set for the observation device by the third transmission frame. Since it is configured, it is possible to easily obtain accurate time information d0b and the correct second timing signal s0c in the plurality of observation devices 120.
(B3) Since the same transmission start time t0 is set for a plurality of observation devices 120 and the delay time t2 can be set to a variable value in all of the plurality of observation devices 120, the transmission start time in the land device 110. The setting of t0 is simplified and the usability is improved, and the land device and all the observation devices can be connected by a single transmission line.
(B4) Since the land device and the observation device and the observation device and the observation device are connected by a single transmission line, the transmission line can be easily constructed.
(B5) Since the time information transmitted by the land device 110 can always be received by all the observation devices 120 and the received time information can be set in the clock circuit 25, some of the observation devices 120 Even when the delay time t2 is set, the other observation devices 120 can set accurate time information in the clock circuit 25, and improve the accuracy of the time information output from the clock circuit 25. Can do.

(Third embodiment)
A time information transmission system according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a diagram showing a configuration of a time information transmission system according to the third embodiment of the present invention, which is an example in which the present invention is applied to a submarine earthquake observation system. In the third embodiment, an observation information transmitter 228 is mounted on the observation device 220, and an observation information receiver 218 is mounted on the land device 210. Accordingly, the observation information can be transmitted from the observation device 220 to the land device 210 via the optical fiber 151.

  5, components that perform the same operations as those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof is omitted. The operation timing in the first embodiment shown in FIGS. 2 and 3 is the same in the third embodiment. That is, FIG. 2 and FIG. 3 are also diagrams showing the operation timing according to the second embodiment.

  In the time information transmission system according to the third embodiment, a one-core bidirectional electric / optical converter 117 is connected between a land device 210 as a time information transmission device and an observation device 220 as a time information reception device. , 127 and a single optical fiber 151 for signal connection.

  Then, the observation information transmission data d5 is transmitted to the land device 210 by switching the switch 229 to the system of the observation information transmission data d5 at a time other than the time information frame return period. Thus, the distribution of time information and the transmission of observation information are made possible with a single optical fiber.

The configuration of the land device 210 will be described.
The land device 210 includes a transmission frame generator 11, a parallel / serial converter 12, a transmission controller 13, a symbol encoder 14, a delay time measuring device 15, a phase synchronization circuit 16, a calculation unit 17, An electric / optical converter 117 and an observation information receiver 218 are included. The difference from the configuration of FIG. 1 is an electrical / optical converter 117 and an observation information receiver 218, and the other configurations are the same as those of FIG. The electric / optical converter 117 has the same configuration as that shown in FIG.

  In the land device 210, the processing clock signal c2 generated by the phase synchronization circuit 16 is used by the phase synchronization circuit 16, and the configuration of the land device 210 is excluded except for the phase synchronization circuit 16 and the electric / optical converter 117. Output to all.

  The observation information receiver 218 decodes the serial observation information transmission data d5b received from the observation device 220, converts it in parallel, and outputs it as observation information. Therefore, the observation information receiver 218 has a configuration necessary as a receiving circuit such as the symbol decoder 21, the serial / parallel converter 22, the reception controller 23, and the like.

Next, the configuration of the observation apparatus 220 will be described.
The observation device 220 includes a symbol decoder 21, a serial / parallel converter 22, a reception controller 23, an AND gate 24, a clock circuit 25, a delay circuit 26, a phase synchronization circuit 27, and an electrical / optical conversion. And a switch 229 and an observation information transmitter 228. The difference from the configuration of FIG. 1 is an electrical / optical converter 127, a switch 229, and an observation information transmitter 228, and other configurations are the same as those of FIG. The electric / optical converter 127 has the same configuration as that shown in FIG.

  In the observation device 220, the processing clock signal c2 generated by the phase synchronization circuit 27 is used by the phase synchronization circuit 27, and the configuration of the observation device 220 is excluded except for the phase synchronization circuit 27 and the electrical / optical converter 127. Output to all.

  The observation information transmitter 228 generates a transmission frame including various observation information d4 observed by an observer (not shown) and time information d0b that is an output of the clock circuit 25, serially converts it, and then encodes the symbol. It is an observation information transmission unit that outputs the observation information transmission data d5 and transmits it to the land device 210. The configuration of the transmission frame is the same as that of the transmission frame d2 shown in FIG. Therefore, the observation information transmitter 228 has a configuration necessary as a transmission circuit such as the frame generator 11, the parallel / serial converter 12, the transmission controller 13, the symbol encoder 14, and the like.

  The connection of the switch 229 is the same as the connection of the switch 129 of the second embodiment (FIG. 4) except that the contact point a is connected to the output of the observation information transmitter 228. That is, the switch 229 switches the observation device 220 between a folded state and a non-folded state. The folded state is a state in which a signal is transmitted from the land device 210, folded back by the observation device 220, and returned to the land device 210. The non-turnback state is a state that is not a return state, and is, for example, a period of the transmission start time t0 in FIG.

  The switch 229 folds back the symbol signal d3b, which is an electric signal from the electric / optical converter 127, to the electric / optical converter 127 during the turn-back state. That is, the contact b of the switch 129 and the electric signal input c of the electric / optical converter 127 are connected.

  In addition, the switch 229 outputs the observation information transmission data d5 from the observation information transmitter 228 to the electrical / optical converter 127 during the non-turnback state. That is, the contact a of the switch 229 and the electrical signal input c of the electrical / optical converter 127 are connected.

  With the above configuration, the observation information d4 is superimposed on the frame for transmitting the observation information d4 after the observation time d0b, which is a time stamp, is added in the observation information transmitter 228, and in the period of the non-folding state, It is output as observation information transmission data d5 which is serial data. The observation information transmission data d5 is converted into an optical signal by the single-core bidirectional electric / optical converter 127 via the switch 229 and output from the observation device 220.

  Observation information output from the observation device 220 is input to the land device 210 via the optical fiber 151. Observation information input to the land device 210 is converted into an electric signal d5b by a single core bidirectional electric / optical converter 117, and observation information d218b to which an observation time d0b as a time stamp is added by an observation information receiver 218. Is output as

  Next, the setting process of the delay time t2 to the delay device 26 in the observation apparatus 220, and the generation process of the time information d0b, the right second timing signal s0c, and the processing clock signal c2 in the observation apparatus 220 will be described. In the present embodiment, it is assumed that the switch 229 is in a folded state in an initial state such as immediately after power-on.

  First, the land device 210 generates frame information d1 (1) in the transmission frame generator 11 after receiving the second signal s0 (1) and time information d0 (1) from the GPS receiver. The frame information d1 (1) is output as a symbol signal d3 from the symbol encoder 14 through the parallel / serial converter 12 in accordance with a control signal from the transmission controller 13. The symbol signal d3 is converted into an optical signal by the electrical / optical converter 117 and output to the optical fiber 151 which is a transmission path.

  The observation device 220 converts an optical signal from the land device 210 sent via the optical fiber 151 into a symbol signal d3b which is an electric signal by the electric / optical converter 127. The electrical signal d3b is turned back by the switch 229 and input to the electrical signal input c of the electrical / optical converter 127. At this time, the observation device 220 is in the folded state, and the contact b of the switch 229 and the electrical signal input c of the electrical / optical converter 127 are connected.

  The land device 210 measures the round trip time from the transmission of the frame information d1 (1) to the return by the observation device 220 using the delay time measuring device 15. Then, similarly to the first embodiment, the delay time t2 is calculated using the signal delay time t1, the transmission start time t0, and the synchronization pattern detection time t3 calculated from the round trip time.

  Next, after receiving the next true second signal s0 (2) and time information d0 (2), the land device 210 generates the next frame information d1 (2) in the transmission frame generator 11, and performs parallel / serial conversion. After being processed by the encoder 12 and the symbol encoder 14, it is output from the electrical / optical converter 117. The frame information d1 (2) includes time information d0 (2) from the GPS receiver and delay time designation information including the delay time t2.

  The frame information d1 (2) is transmitted to the observation device 220, and the delay time t2 is set in the delay device 26 as in the reception device 20 of the first embodiment. Then, in the delay unit 26, the second-second timing signal s0c is generated after the delay time t2 from the synchronization timing signal s0b. Then, in the clock circuit 25, the time information d0 (2) included in the frame information d1b is set by the correct second timing signal s0c. Thereby, the time information d0b indicating the accurate time is output from the clock circuit 25.

  In this way, the observation device 220 can recognize an accurate time. Then, the switch 229 connects the contact b of the switch 229 and the electric signal input c of the electric / optical converter 127 during the turn-back time zone, and the contact time b of the switch 229 during the non-turn-back time zone. Then, the operation of connecting the electrical signal input c of the electrical / optical converter 127 is performed. Then, the observation information transmitter 228 outputs the observation information transmission data d5 to the electrical / optical converter 127 in the non-turn-back time zone.

  Similarly to the first embodiment, the symbol decoder 21 generates serial transmission data d2b, a data acquisition timing signal s3, and a reference clock extraction signal s4 that are received data from the symbol signal d3b. The reference clock signal c1 is extracted from the symbol signal d3b and the reference clock extraction signal s4, and the processing clock signal c2 is generated in the phase synchronization circuit 27 based on the reference clock signal c1.

  In the above description, the switch 229 is used for switching between the time information return state and the observation information transmission state. However, the switch 229 is not necessarily used. For example, in FIG. 5, without using the switch 229, the contact b of the switch 229 and the electric signal input c of the electric / optical converter 127 are fixedly connected, and the contact a and the contact b of the switch 229 are fixed. Are connected to each other, and the observation information from the observation device 220 is superimposed on the optical fiber 151 in a period when the time information from the land device 210 is not superimposed on the optical fiber 151 (a time zone in a non-turned state). A time division method may be used.

According to the third embodiment, at least the following effects can be obtained.
(C1) By connecting a signal between the land device and the observation device with only one optical fiber, the time information d0b, the correct second timing signal s0c, and the processing clock signal c2 in the observation device are converted into the time in the GPS receiver. The accuracy can be close to the information d0, the second signal s0, and the precision clock signal c0.
(C2) The observation device includes a switch for switching between a folded state in which a signal from the land device is folded and transmitted to the land device and a non-turned state in which the signal from the land device is not folded, and the information signal is transmitted from the land device. Is configured to transmit the observation information to the land device while the switch is in the non-turn-back state during the time zone in which the switch is in a folded state and the information signal is not received from the land device. Observation information can be transmitted from the observation device to the land device using only the fiber.

In addition, this invention is not limited to embodiment mentioned above, It can implement in various deformation | transformation and a combination.
In addition, the present invention is understood not only as a system for executing processing according to the present invention, but also as an apparatus and method, a program for realizing such a method and system, and a recording medium for recording the program. can do.
Each component of the present invention may be controlled by a CPU (Central Processing Unit) executing a control program stored in a memory, or may be configured as a hardware circuit that does not use a CPU. Good.

  DESCRIPTION OF SYMBOLS 10 ... Transmission apparatus, 11 ... Transmission frame generator, 12 ... Parallel / serial converter, 13 ... Transmission controller, 14 ... Symbol encoder, 15 ... Delay time measuring device (delay time acquisition part), 16 ... Phase synchronization circuit DESCRIPTION OF SYMBOLS 17 ... Operation part, 20 ... Receiver, 21 ... Symbol decoder, 22 ... Serial / parallel converter, 23 ... Reception controller, 24 ... AND gate, 25 ... Clock circuit, 26 ... Delay device, 27 ... Phase synchronization Circuit, 31 ... Frame information, 32 ... Idle state, 33 ... Synchronization pattern, 34 ... Time information, 35 ... Other information, 51 ... Communication cable, 110 ... Land equipment, 111 ... Transmission frame generator, 117 ... Electric / optical conversion 120 ... observation device 122 ... series / parallel converter 127 ... electric / optical converter 128 ... electric / optical converter 129 ... switch 151 ... optical fiber 210 ... land device 21 ... Observation information receiver, 220 ... Observation device, 228 ... Observation information transmitter, 229 ... Switch, c0 ... Precision clock signal, c1 ... Reference clock signal, c2 ... Processing clock signal, d0, d0b ... Time information, d1, d1b ... frame information, d2, d2b ... serial transmission data, d3, d3b, d3c ... symbol signal, d4 ... observation information, d5, d5b ... observation information transmission data, d01 ... setting request information, d02 ... observation device designation information, d03 ... turn-up designation information, s0 ... correct second signal, s0b ... synchronization timing signal (reference timing signal), s0c ... correct second timing signal, s1 ... transmission start signal, s2 ... symbol timing signal, s3 ... data capture timing signal, s4 ... reference clock extraction signal, s5 ... serial / parallel conversion period signal, t0 ... transmission start time, t1 ... signal delay time, t ... delay time, t3 ... synchronization pattern detection time.

Claims (12)

The time information is received from the outside at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information, and an information signal including the time information is received. A time information transmission system comprising: a transmission device that transmits at the period T; and a reception device that receives the information signal from the transmission device via a transmission path,
The transmitter is
A delay time acquisition unit for acquiring a signal delay time t1 by the transmission line;
A calculation unit that calculates a delay time t2 using the signal delay time t1 and generates delay time designation information including the delay time t2,
A frame information transmission unit that generates frame information including the time information and the delay time designation information and transmits the frame information as the information signal;
The receiving device is:
A decoding unit that extracts, from the frame information received from the transmission device, a reference timing that serves as a reference for extracting a correct second timing that is the same as the correct second signal timing, and that restores the time information and the delay time designation information When,
Based on the reference timing and the delay time t2 included in the delay time designation information, the true second timing is extracted, the time information is set in the clock circuit at the true second timing, and the real time information is obtained from the clock circuit. A clock part to output,
A time information transmission system comprising: The time information transmission system according to claim 1,
The transmission device includes a processing clock signal generation unit that generates a processing clock signal,
The frame information transmission unit encodes the frame information using the processing clock signal, and includes an information signal including the time information, the delay time designation information, and a reference clock signal obtained by dividing the processing clock signal Send as
The time information transmission system, wherein the decoding unit extracts the reference clock signal from the information signal received from the transmission device, and restores the processing clock signal based on the extracted reference clock signal. The time information transmission system according to claim 1,
The transmitter is
By transmitting the first information signal to the receiving device and receiving the first information signal returned from the receiving device, the signal delay time t1 is obtained, the frame information is generated, 2 to the transmitter as an information signal,
The receiving device is:
Receiving the second information signal, taking out the reference timing from the second information signal, restoring the time information and the delay time designation information, and based on the reference timing and the delay time t2 The time information transmission system, wherein the second time is taken out. The time information transmission system according to claim 1,
The arithmetic unit sets time t3 after the reception device starts receiving the frame information to take out the reference timing, and transmits the frame information after the transmission device receives the second signal from the outside. The time information transmission system according to claim 1, wherein t2 is calculated using T, t0, t1, and t3 when time to start is t0. The time information transmission system according to claim 1,
The transmission device acquires the signal delay time t1 and generates the delay time designation information every time the time information is received at the period T, and generates the frame information including the generated delay time designation information. Then send
Each time the receiving apparatus receives the frame information, the receiving apparatus extracts the reference timing and restores the time information and the delay time designation information. Based on the reference timing and the delay time t2, the receiving device calculates the second time timing. A time information transmission system characterized by being taken out. The time information transmission system according to claim 1,
The receiving apparatus is a first receiving apparatus, and includes a second receiving apparatus having the configuration of the receiving apparatus. The transmitting apparatus, the first receiving apparatus, and the second receiving apparatus are arranged in this order. Signal connected in the form
The first receiving device loops back a signal from the transmitting device and transmits the signal to the transmitting device and a signal from the second receiving device without returning the signal from the transmitting device to the transmitting device. A first switch that switches between a non-wrapped state to transmit,
The second receiving device includes a folded state in which a signal from the first receiving device is folded and transmitted to the first receiving device, and a non-folded state in which the signal from the first receiving device is not folded. A second switch to switch between,
The transmitter is
A first information signal for setting the first receiving device in a folded state is transmitted to the first receiving device, and then a second information signal is transmitted to the first receiving device, and the first information signal is transmitted to the first receiving device. A first signal delay time t1 (1) by a transmission path between the transmitting device and the first receiving device is received by receiving the second information signal returned from the receiving device of A delay time t2 (1) is calculated using the first signal delay time t1 (1), first delay time designation information including the delay time t2 (1) is generated, and the first delay time is generated. Transmitting a third information signal including designation information to set the first receiving device in a non-turn-back state to the first receiving device;
The first receiving device is:
When the first information signal is received, the first switch is turned back, and when the second information signal is received, the received second information signal is sent back to the transmitter, and the third information signal is transmitted. When the information signal is received, the first switch is set in a non-turn-back state, the reference timing is extracted from the third information signal and the first delay time designation information is restored, and the reference timing and the delay time t2 are restored. Based on (1), the above-mentioned second timing is taken out,
The transmitter is
A fourth information signal for setting the second receiving device in a folded state is transmitted to the second receiving device via the first receiving device, and then a fifth information signal is sent to the first receiving device. Transmitting to the second receiving device via the receiving device, and receiving the fifth information signal returned from the second receiving device via the first receiving device; The second signal delay time t1 (2) by the transmission path to the second receiving device is acquired, and the delay time t2 (2) is calculated using the second signal delay time t1 (2). Generating a second delay time designation information including the delay time t2 (2), and a sixth information signal including the second delay time designation information and setting the second reception device in a non-folding state. , Transmit to the second receiver via the first receiver,
The second receiving device is:
When the fourth information signal is received via the first receiving device, the second switch is turned back, and when the fifth information signal is received via the first receiving device, the received second information signal is received. When the information signal of 5 is sent back to the transmitting device via the first receiving device and the sixth information signal is received via the first receiving device, the second switch is turned off. In a folded state, the reference timing is extracted from the sixth information signal and the second delay time designation information is restored, and the correct second timing is extracted based on the reference timing and the delay time t2 (2). A time information transmission system characterized by that. The time information transmission system according to claim 6,
The transmission device converts the electrical signal generated by the transmission device into an optical signal, outputs the optical signal to the first reception device, and converts the optical signal from the first reception device into an electrical signal. With an electrical / optical converter,
The first receiving device converts the electrical signal generated by the first receiving device into an optical signal, outputs the optical signal to the transmitting device, and converts the optical signal from the transmitting device into an electrical signal. The electrical signal generated by the electrical / optical converter and the first receiving device is converted into an optical signal and output to the second receiving device, and the optical signal from the second receiving device is converted into an electrical signal. A third electrical / optical converter to convert,
The second receiving device converts the electrical signal generated by the second receiving device into an optical signal, outputs the optical signal to the first receiving device, and outputs the optical signal from the first receiving device to the electrical signal. A fourth electrical / optical converter for converting to
A time characterized in that a single optical communication cable is connected between the transmitting device and the first receiving device, and between the first receiving device and the second receiving device. Information transmission system. The time information transmission system according to claim 1,
The receiving device further includes an observation information sending unit for sending observation information to the transmitting device, a folded state in which a signal from the transmitting device is folded and transmitted to the transmitting device, and a signal from the transmitting device is not folded. A switch that switches between a non-turn-back state, a time zone in which the information signal is received from the transmission device is a time zone in which the switch is in the loop-back state and the information signal is not received from the transmission device, A time information transmission system, wherein the switch is set to the non-turned state, and the observation information from the observation information sending unit is transmitted to the transmitting device in the time zone of the non-turned state. A time information transmission system according to claim 2,
When receiving the reference clock signal, the receiving device extracts the information signal received from the transmitting device at a gate without sampling. The time information transmission system according to claim 1,
The frame information transmission unit generates frame information including a synchronization pattern, the time information, and the delay time designation information,
The decoding unit, from the frame information received from the transmission device, takes out the synchronization timing when the synchronization pattern is detected as the reference timing,
The time information transmission system according to claim 1, wherein the timepiece unit sets the time information in a timepiece circuit at the true second timing based on the synchronization timing and the delay time t2. The time information is received from the outside at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information, and an information signal including the time information is received. A transmission device for transmitting in the period T,
A processing clock signal generator for generating a processing clock signal;
A delay time acquisition unit for acquiring a signal delay time t1 by the transmission line;
A calculation unit that calculates a delay time t2 using the signal delay time t1 and generates delay time designation information including the delay time t2,
Frame information including the time information and the delay time designation information is generated, the frame information is encoded using the processing clock signal, and the time information, the delay time designation information, and the processing clock signal are separated. A frame information transmitter for transmitting as an information signal including a reference clock signal that has been rotated;
A transmission device comprising: From the outside, the time information is received at a predetermined period T, and the second signal indicating the actual timing indicated by the time information is received at the period T later than the time information from the transmission device via the transmission path. Receiving the first frame information including the time information or the second frame information including the time information and delay time designation information in the period T,
A decoding unit that extracts the reference timing from the second frame information received from the transmission device and restores the time information and the delay time designation information;
Based on the reference timing and the delay time t2 included in the delay time designation information, the correct second timing of the same timing as the correct second signal timing is taken, and the time information is set in the clock circuit at the correct second timing, A clock unit for outputting real time information from the clock circuit;
A receiving apparatus comprising:

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