JP7312779B2 - Information communication system and information communication device - Google Patents

Description

The present invention relates to an information communication system and an information communication device for synchronizing a plurality of information communication devices through communication.

IEEE1588 Precision Time Protocol (PTP) of Non-Patent Document 1, for example, is known as a general time synchronization method between a plurality of information communication devices. Non-Patent Document 1 defines a master device that has a reference time and a slave device that time-synchronizes with the time of the master device, and corrects the time of the slave device by periodically exchanging time-synchronization packets between the master device and the slave device.

Specifically, using the transmission time of the master device and the reception time of the slave device of the packet transmitted from the master device to the slave device, and the transmission time of the slave device and the reception time of the master device of the packet transmitted from the slave device to the master device, the slave device estimates and corrects the time offset, which is the time difference between the master device and the slave device.

"IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems." IEEE Standard 1588-2008.

In the PTP system, even if synchronization has been established between the master device and the slave device, there are cases where the synchronous state transitions to the asynchronous state due to some factor and the synchronization is lost. For example, there are the following factors for such out-of-synchronization.
(a) Synchronization phase, which is the difference (difference) between the times of the master device and the slave device, becomes excessive (b) The master device is switched (c) Synchronization information cannot be received from the master device (d) The status and settings of the master device change (e) An abnormality occurs in the external interface or communication path that communicates synchronization information

Here, even if the slave device is out of synchronization with the master device, the subsystem that refers to the timing information for synchronization can maintain a steady and stable operation and the synchronization phase is continuous. Once the synchronous state transitions to the asynchronous state, even if the cause of the loss of synchronization is resolved, synchronous continuity is not guaranteed, and discontinuous resynchronization occurs.

In a subsystem that uses synchronized timing information, such as a timing information reference unit, for example, when an audio signal is being transmitted, discontinuous resynchronization causes problems such as noise in the audio and audio interruptions, leading to deterioration in operation quality.

However, if these factors are eliminated within a predetermined period of time, there are cases where synchronization can be maintained as long as the operating quality of the subsystem does not deteriorate even if the transition to the asynchronous state does not occur.

Therefore, there is a demand for a system that can maintain the continuity of the synchronized state, realize seamless synchronization between devices with the same clock performance, and allow subsystems that refer to synchronized timing information to operate continuously.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems described above, and it is an object of the present invention to provide an information communication system and an information communication apparatus capable of maintaining continuity of synchronization.

The present invention is an information communication system in which a plurality of information communication devices communicates information as a master device or a slave device, wherein the information includes synchronization information for synchronizing time between the master device and the slave device, and priority information including information indicating whether the possibility of being selected as the master device is high or low. a timing information reference unit for performing processing in synchronization with timing information; an inertial synchronization processing unit for suspending a transition from the synchronous state to an asynchronous state in which synchronization is lost based on the synchronization phase while the timing information reference unit is performing processing in synchronization with the timing information when a factor causing loss of synchronization occurs, and transitioning to an inertial synchronization state in which continuous synchronization is maintained; a role determination unit that determines a role of an information communication device whose role is undetermined based on priority information to be transmitted to the communication device and priority information received from another information communication device;

The information communication device of the present invention performs information communication with other information communication devices in the role of a master device or a slave device.A synchronous network is constructed by multiple information communication devices of the same or similar type.An information communication device, wherein the information includes synchronization information for synchronizing time with another information communication device and priority information including information indicating whether the possibility of being selected as a master device is high or low, a synchronization control unit that synchronizes with the other information communication device by controlling a synchronization phase based on the synchronization information, a timing information reference unit that refers to the timing information indicating the synchronized timing output from the synchronization control unit and performs processing in synchronization with the timing information, and a factor that causes the synchronization to be lost. an inertial synchronization processing unit that suspends a transition from the synchronous state to an asynchronous state that loses synchronization and transitions to an inertial synchronous state that maintains continuous synchronization based on the synchronous phase while the timing information reference unit performs processing in synchronization with the timing information; priority information that, when an information communication device whose role is undetermined as a master device and a slave device is activated, the information communication device whose role is undetermined sends itself to another information communication device as a low-level device; and priority information received from the other information communication device. Based onowna role determination unit that determines the role of the device;A ranking list generating unit that generates a master ranking list indicating the order in which slave devices are selected as master devices based on synchronization quality information from a plurality of slave devices; a presence information distribution unit that distributes presence information indicating that each slave device that has received the master ranking list is connected to the synchronization network of the slave devices;have

According to the present invention, it is possible to obtain an information communication system and an information communication device capable of maintaining continuity of synchronization.

1 is a schematic diagram of an information communication system according to an embodiment; FIG. 1 is a functional block diagram of an information communication device that constitutes an information communication system according to an embodiment; FIG. 4 is a functional block diagram of a control unit according to the embodiment; FIG. It is a figure which shows the aspect of the communication for synchronizing the information communication system which concerns on embodiment. 4 is a state transition diagram including an inertial synchronization state and a quasi-synchronization state of the information communication system according to the embodiment; FIG. FIG. 10 is a flow chart showing a procedure of processing when transitioning from a semi-synchronous state to a synchronous state or an asynchronous state; FIG. 4 is a state transition diagram including an inertia synchronization state, a semi-synchronization state, and a semi-time distribution state of the information communication system according to the embodiment; FIG. 4 is a flow chart showing a procedure for role determination based on priority; FIG. 10 is a sequence diagram showing a procedure for master determination based on the master order list;

Hereinafter, an information communication system and an information communication device according to embodiments will be described with reference to the drawings.

[composition]
FIG. 1 is a schematic diagram of an information communication system 100 according to an embodiment. FIG. 2 is a functional block diagram of the information communication device 1 configuring the information communication system 100 according to the embodiment. FIG. 3 is a functional block diagram of the controller 70 of FIG.

The information communication system 100 according to the present embodiment is composed of a plurality of information communication devices 1, and each information communication device 1 is synchronized by information communication. The information communication device 1, which is a slave device, synchronizes with the information communication device 1, which is a master device. A master device is an information communication device 1 to be synchronized with another information communication device 1 in the information communication system 100 . A slave device is an information communication device 1 that synchronizes with another information communication device 1 that is a master device in the information communication system 100 . The slave device synchronizes with the master device through transmission and reception of synchronization information, which is information for achieving time synchronization from the master device to the slave device.

In the following description, the information communication device 1 serving as a master device is referred to as a master device 1a, and the information communication device 1 serving as a slave device is referred to as a slave device 1b. At least one slave device 1b may exist for the master device 1a, but as shown in FIG. 1, the system may include a plurality of slave devices 1b.

The master device 1a and the slave device 1b communicate information by wire or wirelessly. Here, an example will be described in which the information communication device 1 achieves synchronization by transmitting and receiving information by wire.

The information communication device 1 may be configured as a synchronous relay device having the functions of both the master device 1a and the slave device 1b. A synchronous repeater corresponds to a boundary clock in PTP. In this case, the network connected to the slave device 1b side is assumed to be an upper synchronization network, and the network connected to the master device 1a side is assumed to be a lower synchronization network. Timing information synchronized in the upper synchronization network on the side of the slave device 1b is transmitted to the lower synchronization network via the master device 1a.

(Information communication device)
The information communication device 1 includes a computer, and a processor, such as a CPU, executes a program stored in advance in a storage unit such as an HDD or SSD, thereby performing necessary calculations in a control unit, which will be described later.

Specifically, as shown in FIG. 2, the information communication device 1 has a communication section 10, a clock 20, a clock 30, a storage section 50, an external interface 60, and a control section . For example, each unit 10 to 70 is configured as hardware. Each unit of the control unit 70 may be configured by software including programs and data. It is possible to appropriately change the design of which part of the control unit 70 is configured as software.

The communication unit 10 transmits and receives information to and from another information communication device 1 . The communication section 10 has a transmitter 11 , a receiver 12 , a transmission timing detection section 13 and a reception timing detection section 14 .

The transmitter 11 is a device that transmits input information. Specifically, the transmitter 11 decomposes the information into the minimum components in time series and transmits the information to the outside. The information packet length (amount of communication information) is arbitrary and may differ for each communication. For example, an input unit for converting an audio signal input from a microphone into audio data is connected to the information communication device 1, and audio data as information is input to the information communication device 1 from the input unit.

The receiver 12 is a device that receives information from the outside. Specifically, the receiver 12 reconstructs the information received from the outside of the information communication device 1 and is decomposed into the minimum components in time series, and outputs the reconstructed information to other components within the information communication device 1 . For example, a reproducing unit such as an ear receiver or a speaker that outputs audio is connected to the information communication device 1, and the receiver 12 converts audio data into an audio signal and outputs the audio signal to the reproducing unit.

Here, the information communicated by the information communication device 1, that is, the information transmitted by the transmitter 11 and the information received by the receiver 12 includes synchronization information, timing information, and clock quality information, which will be described later.

Information communication device 1 has both transmitter 11 and receiver 12 . In the case of wireless communication, the transmitter 11 and the receiver 12 may each be provided with an antenna, or a switch may be provided to share one antenna.

The transmission timing detector 13 detects transmission timing. The transmission timing is the timing at which a predetermined information element position of the information transmitted by the transmitter 11 is transmitted to the outside of the information communication device 1 . This transmission timing is detected based on the clock period of the clock 20 (in other words, the period of the pulse generated by the clock 20), which will be described later. That is, the transmission timing is expressed based on an integer multiple of the clock period.

Also, the transmission timing detection unit 13 outputs the detection result to other components in the information communication device 1 . The information referred to here is, for example, a packet, and in this case, a predetermined information element position (hereinafter referred to as a predetermined information element position) is a bit position. For example, when information is decomposed into eight minimum component bits in time series, the transmission timing detection unit 13 detects the timing at which the third information element position (bit position) is transmitted, and outputs the timing at which the third information element position (bit position) is transmitted to the outside.

The reception timing detection unit 14 detects the reception timing, which is the timing at which the predetermined information element position of the information received by the receiver 12 is received from the outside of the information communication device 1 . This reception timing is detected based on the clock period of the clock 20, which will be described later. That is, the reception timing is expressed as an integral multiple of the clock period.

Also, the reception timing detector 14 outputs the detection result to other components in the information communication device 1 . For example, when the information is decomposed into eight minimum constituent bits in time series, the reception timing detection unit 14 detects the timing at which the third information element position (bit position) is received, and outputs the timing at which the third information element position (bit position) is received to the outside.

In the above example of the transmission timing and the reception timing, the position of the same minimum component is detected. However, the transmission timing detection unit 13 of the information communication device 1 as a transmitter detects the fifth element, and the reception timing detection unit 14 of the information communication device 1 as a receiver detects the eighth element.

Also, the transmission timing may be detected before or after a specified time from the actual transmission timing. The reception timing may be detected before or after a specified time from the actual reception timing. These default values may be fixed within the communication unit, or set statically or dynamically from the outside. Note that "regulation" is synonymous with "predetermined" and "predetermined".

The clock 20 oscillates at a predetermined frequency and outputs a signal for giving operation timing to each part of the information communication device 1 . Thereby, each part in the information communication device 1 operates in synchronization with the clock 20 . The entire information communication device 1 may be synchronized with a single clock 20 all at once, or may be independently synchronized with a plurality of clocks 20 for each of a plurality of functional units. This clock 20 has an inherent finite oscillation frequency tolerance. That is, the clock 20 has an error (eg, 20 ppm) with respect to a predetermined oscillation frequency (eg, 10 MHz). As the clock 20, for example, a fixed-frequency oscillator such as a crystal oscillator can be used.

Even if the nominal frequency of the clock 20 is the same between the master device 1a and the slave device 1b, individual differences actually exist. That is, there is a frequency deviation between the frequencies of the clocks 20 of the master device 1a and the slave device 1b. The clock 20 may receive a frequency control signal from the outside and variably control the oscillation frequency corresponding to the signal.

The clock 30 keeps time using the output signal of the clock 20 as a source oscillation, and outputs the relative time since the start-up of the information communication device 1 . Clocking may be synchronized with the divided frequency of the input clock signal. Also, the time may be variable in advance width per clock, or the drive frequency of the clock may be intermittently controlled even if the clock frequency is fixed. The time is referred to in a prescribed unit, and this prescribed value may be fixed within the clock or set statically or dynamically from the outside. The output of the relative time of the clock 30 is performed, for example, in response to an external reference request.

The storage unit 50 is a recording medium such as an HDD, SSD, memory, register, or the like. The storage unit 50 stores information necessary for the control unit 70 to perform calculations. The time of the clock 30 corresponding to transmission timing or reception timing, which will be described later, should preferably be stored in a recording medium that can be stored only by hardware access without intervention of the CPU or software. This is because jitter caused by software can be eliminated. Note that it is important not to suffer software jitter in associating the transmission/reception timing with the time, and after the transmission/reception timing and the time are associated, they may be stored in a low-speed access area.

The memory as the storage unit 50 inputs and outputs arbitrary information and stores the information in a designated storage area. Information is stored according to a storage request from the outside. At that time, information to be stored and a storage area are input. Information is referenced by a reference request from the outside. At that time, the storage area of the reference information is input, and the information in the storage area specified by the input is output. Information may be retained in memory only while the device is in operation, or may be permanent, including when the device is not in operation.

An external interface 60 (hereinafter also referred to as an external I/F 60) connects the inside and outside of the information communication device 1 and inputs/outputs arbitrary information. The information includes transmitted/received data and the time of the clock 30 . The external I/F 60 acquires information to be stored in the storage unit 50 from the outside, for example. Further, the external I/F 60 may acquire the time from the reception timing detected by the reception timing detection section 14 to the transmission timing detected by the transmission timing detection section 13 from the outside, and use the obtained time in the scheduler 77 described later.

Note that the master device 1a has at least an external I/F 60 that transmits synchronization information. The slave device 1b has an external I/F 60 that receives at least synchronization information. However, the master device 1a may have an external I/F 60 for receiving synchronization information, and the slave device 1b may have an external I/F 60 for transmitting synchronization information. Furthermore, the information communication device 1 may have a user interface such as a display device capable of controlling and displaying the internal state.

The control unit 70 controls overall operations of each unit of the information communication device 1 . FIG. 3 is a functional block diagram of the control section 70. As shown in FIG. As shown in FIG. 3, the control unit 70 includes a main control unit 71, a transmission/reception data I/F 72, a communication control unit 73, a time recording unit 74, a scheduler 77, a frequency deviation calculation unit 78, a synchronization control unit 79, a timing information reference unit 80, an inertial synchronization processing unit 81, a semi-synchronization processing unit 82, a fluctuation control unit 83, a clock quality information output unit 84, a selection unit 85, a suppression unit 86, a re-selection unit 87, a role determination unit 88, a ranking list generation unit 89, a presentation It has a master information distribution unit 90 and a master determination unit 91 .

The main control section 71 cooperates with each section in the control section 70 and controls the operation of each section in the control section 70 . The transmission/reception data I/F 72 puts the information of the storage unit 50 and the external I/F 60 into a format that can be transmitted to the outside of the device. Also, the transmission/reception data I/F 72 converts information received from outside the device into a format suitable for the control unit 70 and the storage unit 50 .

The communication control section 73 controls the operation of the communication section 10 . The communication control unit 73 inputs and outputs transmission/reception information between the communication unit 10 and the control unit 70 .

The time recording unit 74 associates the transmission timing of the predetermined information element position of the information transmitted by the transmission timing detection unit 13 with the time of the clock 30 at the transmission timing, and stores them in the memory of the storage unit 50 . For this association, for example, the time recording unit 74 receives a signal from the transmission timing detection unit 13 indicating that the transmission timing of the predetermined information element position of the transmitted information has been detected, refers to the time of the clock 30, and associates the time with the transmission timing.

The time recording unit 74 also serves as a time addition unit that adds the time corresponding to the transmission timing to the information to be transmitted. The time recording unit 74 associates the reception timing of the predetermined element position of the information received by the reception timing detection unit 14 with the time of the clock 30 at the reception timing, and stores it in the memory, as in the transmission. In addition, the time recording unit 74 causes the transmitter 11 to transmit the time corresponding to the reception timing on the information.

Thus, in this embodiment, "time" refers to the time of the clock 30 corresponding to the detected transmission timing or reception timing of the predetermined information element position of information, and "time" refers to the difference between the times.

A scheduler 77 controls the schedule (time) for transmitting or receiving information. For example, in the case of unidirectional communication of information, the scheduler 77 on the transmitting side controls information transmission intervals and sets a schedule in which information transmission timing is detected at a predetermined time. Also, the scheduler 77 may control the time from reception of information to transmission. When transmitting information, the communication control unit 73 can include the time corresponding to the transmission timing of the preset schedule or the detected transmission timing in the information.

The frequency deviation calculator 78 calculates the difference between the clock frequency of the information communication device 1 to be synchronized (master device 1a) and the clock frequency of the information communication device 1 to be synchronized (slave device 1b). The difference in this clock frequency (hereinafter also simply referred to as "frequency") is a frequency ratio or frequency deviation. The frequency deviation calculator 78 of this embodiment obtains the frequency ratio or the frequency deviation from the time difference of the clocks 20 between the information communication devices 1 and the information propagation time between the information communication devices 1 .

In this embodiment, the frequency ratio is the ratio r of the clock frequency of the slave device to the clock frequency of the master device (hereinafter referred to as clock frequency ratio, or simply frequency ratio). The frequency deviation is the difference between the clock frequency of the master device and the clock frequency of the slave device, and the frequency deviation e can be obtained by e=r−1.

The synchronization control section 79 controls the clock 20 or the clock 30 based on the frequency ratio or frequency deviation calculated by the frequency deviation computing section 78 .

In other words, the synchronization control unit 79 calculates the time difference from the information communication device 1, which is the device to be synchronized (master device), based on the frequency ratio or the frequency deviation obtained by the frequency deviation calculation unit 78, and corrects the value ticked by the clock 30 based on the difference. For example, the time may be corrected by controlling the clock 30 itself. Alternatively, correction may be made based on the time lag when the clock 30 outputs the time. That is, the time itself of the clock 30 may not be corrected, and the clock 30 may be controlled so as to output the time corrected for the deviation when the clock 30 outputs the time.

The timing information reference unit 80 refers to the timing information output from the synchronization control unit 79 and executes desired processing in synchronization therewith. The timing information is composed of a periodic timing signal and time information uniquely corresponding to the specified timing. The synchronization control section 79 can synchronize with other information communication devices 1 based on the timing information. In the synchronous repeater, the timing information synchronized with the upper synchronous network is transmitted to the lower synchronous system.

When a factor causing loss of synchronization occurs, the inertial synchronization processing unit 81 suspends the transition from the synchronous state to the asynchronous state in which synchronization is lost based on the synchronization phase while the timing information reference unit 80 performs processing in synchronization with the timing information, and makes the transition to the inertial synchronization state in which continuous synchronization is maintained. The inertial synchronous state is a state in which the synchronous phase required by the system cannot be maintained, but the transition to the asynchronous state is not made. The inertia synchronization processing unit 81 controls mutual state transitions between the synchronous state and the inertia synchronous state, and mutual state transitions between the inertia synchronous state and the asynchronous state.

In the asynchronous state, the quasi-synchronous processing unit 82 suspends the transition to the synchronous state after the synchronous control by the synchronous control unit 79 is started until a predetermined synchronous phase is reached. The quasi-synchronous state is a state of waiting for a synchronous state until the synchronous phase is stabilized. In other words, the quasi-synchronous state is a transitional state in which the above-mentioned four measurement values necessary for time synchronization can be received and the clock frequency can be controlled without any problem, but the synchronization accuracy required by the system is not achieved. The quasi-synchronous processing unit 82 controls mutual state transitions between the asynchronous state and the quasi-synchronous state, and mutual state transitions between the quasi-synchronous state and the synchronous state.

The variation control unit 83 limits the speed of the synchronous phase change for synchronization within a predetermined range, and controls the acceleration of the synchronous phase change to vary according to a continuous function. That is, the variation control unit 83 avoids discontinuous switching of the synchronous phase by imposing restrictions on the velocity and acceleration of the synchronous phase variation.

The clock quality information output unit 84 outputs clock quality information. The clock quality information is a set of statically set values such as clock accuracy and priority, and corresponds to PTP ANNOUNCE packets.

The selection unit 85 selects one of the information communication devices 1 as at least one of the master device 1a and the slave device 1b based on the clock quality information. The suppression unit 86 suppresses the switching of the master device 1a to the slave device 1b due to the selection by the selection unit 85 by causing the clock quality information output unit 84 of the information communication device 1 at startup to withhold the output of the clock quality information. When the re-election unit 87 detects that the master device 1a has left the information communication system 100, the re-selection unit 87 makes a transition to the synchronous state or the inertial synchronization state, and re-selects one of the information communication devices 1 as the master device 1a.

The role determination unit 88 determines the role of the information communication device 1 whose role is undetermined based on the priority order information. This priority order information is information that includes information regarding the order of priority as to whether the possibility of being selected as the master device 1a is high or low. The priority may be binary information assigned to low and high ranks, or may be multi-valued information larger than binary information from low to high ranks to set a plurality of ranks.

When an information communication device 1 whose roles as a master device 1a and a slave device 1b are undetermined is connected to a synchronous network by activation, the information communication device 1 whose role is undetermined transmits priority order information in which its own device is low to other information communication devices 1.例文帳に追加Role determination unit 88 determines a role based on the priority information of its own device and the priority information received from other information communication devices 1 . If the priority of the own device is lower than the priority of other devices, the device becomes the slave device 1b. If the priority of the own device is higher than the priority of other devices, the own device becomes the master device 1a. If no priority order information is received from the other device even after a specified period of time has passed, the priority order information of its own device is sent to the other information communication device 1 as high order information, and the slave device 1b and the master device 1a are determined as described above.

The ranking list generator 89 generates a master ranking list indicating the ranking in which the slave device 1b is selected as the master device 1a. A master ranking list is generated based on the synchronization quality received from each slave device 1b. The presence information distribution unit 90 distributes presence information indicating that each slave device 1b is connected to the synchronous network. The master determining unit 91 determines the slave device 1b to be the new master device 1a based on the master order list and presence information.

[motion]
The operation of the information communication system 100 having the above configuration will be described. The information communication system 100 of the present embodiment uses information communication to measure the clock time difference between the information communication devices 1 and the propagation time of the information communication between the information communication devices 1, and correct the time difference, thereby realizing time synchronization between the information communication devices 1.

Furthermore, it is possible to maintain basic synchronous continuity in an environment where there is a disturbance to the synchronous quality, synchronous continuity when switching roles between the master device and the slave device, and synchronous continuity between synchronous systems in a synchronous repeater.

[Time synchronization]
First, an example of time synchronization by the frequency deviation calculator 78 and the synchronization controller 79 will be described. This time synchronization is performed by measuring the time difference of the clock 20 between the information communication devices 1 and the information propagation time between the information communication devices 1 and correcting this time difference.

As shown in FIG. 4, the master device 1a transmits synchronization information to the slave device 1b, the slave device 1b receives the information after the propagation time, the master device 1a transmits another synchronization information after the reception, and the master device 1a receives the information after the same propagation time. Here, the synchronization information transmitted by the master device 1a and the separate synchronization information transmitted by the slave device 1b are for the purpose of measuring the timing for synchronization, and the synchronization information may include the transmission time of the synchronization information of the master device 1a, but the contents of the synchronization information and the other synchronization information are arbitrary.

In FIG. 4, information is transmitted from the master device 1a at time _tm,T and received by the slave device 1b at time _{ts ,R} after a propagation time td. After Δt _s , another information is transmitted from the slave device 1b at time _ts,T , and after the propagation time _td , the master device receives the information at time _tm,R .

なお、伝搬時間ｔ_ｄは、情報通信の方向において、対照的であることを前提としている。 Here, it is assumed that the interval from transmission to reception in the master device 1a is _Δtm , the interval from reception to transmission in the slave device 1b is _{Δts , and the same timing as the transmission timing tm,T} of the master device 1a is observed as _t′m,T in the slave device 1b. Therefore, the time difference _t0 between the clock 20 and the slave device 1b with respect to the master device 1a can be obtained according to equation (1).

It is assumed that the propagation times _td are symmetrical in the direction of information communication.

From these conditions, the propagation time _td can be obtained as shown in Equation (2).

Therefore, the time difference t ₀ between the clocks 20 can be obtained from the equation (3) using the equation (2).

The synchronization control unit 79 of the slave device 1b can time-synchronize with the master device 1a by repeatedly adjusting the clock frequency and time so that _t0 becomes zero.

If the clock frequencies of the master device 1a and the slave device 1b are the same, that is, if the clock domain is single, time synchronization can be achieved simply by adjusting the time once. However, since there is generally a frequency deviation between the two clocks, adjustment of the clock frequency is essential for time synchronization. Even in a system in which the clock frequency cannot be directly adjusted, it is possible to control the drive frequency of the clock and synchronize the time by repeatedly adjusting the time advance width per clock.

For these frequency adjustments, a synchronous phase is input and a frequency adjustment value is output. Closed-loop control is periodically performed to control the output value so that the input synchronous phase is zero.

Propagation time and internal delay between transmission and reception timings can be ignored or corrected depending on system requirements. Further, the synchronization information may be transmitted from the slave device 1b instead of starting the transmission of the synchronization information from the master device 1a. Furthermore, although one interface is sufficient for information communication, a configuration in which multiple interfaces are used at the same time, such as independent implementation of transmission and reception interfaces, is also possible.

[Synchronization with linked subsystems]
(inertial synchronization)
Synchronization performed by subsystems in cooperation will be described with reference to the state transition diagram of FIG. This synchronization includes an inertial synchronization state. The quasi-synchronous state will be described later. The subsystem is a part of the information communication system 100, and is a system composed of hardware and application programs that perform time synchronization and information output. In this embodiment, in the information communication device 1, a system that performs time synchronization and transmits voice corresponds to a subsystem.

In the following description, a state machine is a logic circuit that determines the next state based on the input conditions and the current state, and changes the state according to the input conditions. In this embodiment, the synchronization control unit 79 and the like in the slave device 1b function as a state machine that switches between various states according to the factors that have occurred.

FIG. 5 is a modeled state transition diagram of a state machine for time synchronization control executed by cooperation of subsystems. This linkage is performed by state transitions between two states in the upper hierarchy, the timing information non-reference state and the timing information reference state. Triggered by the reference start/end event of the timing information of the subsystem, it transitions to one of the states.

The timing information non-referencing state shown in the upper frame of FIG. 5 corresponds to a normal operating state in which the PTP is simply operating. The timing information reference state shown in the lower frame of FIG. 5 differs from the timing information non-reference state in that the inertia synchronization state by the inertia synchronization processing unit 81 is included. When the inertia synchronization processing unit 81 transitions to the inertia synchronization state, even if the synchronization phase is unstable or cannot be calculated, it is recovered in a short time, and there is a factor that eliminates the necessity of immediately changing to the asynchronous state and losing the continuity of synchronization. In such a case, it is conceivable that there is noise in the communication of the synchronization information, or that the cable connection is faulty. Even in this case, the transmission of timing information continues.

In the inertia synchronization processing unit 81, when these factors are resolved and the synchronization phase is stabilized in the inertia synchronization state, the inertia synchronization processing unit 81 transitions to synchronization without going through the asynchronous state. As a result, it is possible to continue communication while maintaining synchronous continuity without easily transitioning to the asynchronous state and interrupting the voice. In the inertial synchronous state, if the permissible condition of the subsystem is deviated, the time synchronous control information is reset and the state is changed to the asynchronous state.

More specifically, for example, even if the synchronous phase (time lag) exceeds the threshold for the asynchronous state in PTP, the inertial synchronization processing unit 81 does not put the PTP in the asynchronous state, but puts it in the inertial synchronous state. However, when the synchronous phase exceeding the threshold value continues for a predetermined time, it is assumed to be in an asynchronous state. The predetermined time is the time required for the synchronization phase exceeding the threshold value to become zero.

Each state of the upper layer includes a state machine of the lower layer mainly for time synchronization control, and states with the same name are transparent. That is, if the lower layer of the timing information non-referencing state is in the synchronous state, the state of the lower layer becomes the synchronous state even if the transition to the timing information referencing state is made. However, when the lower layer is in the inertial synchronization state, if the upper layer transitions to the timing information non-reference state, the time synchronization control information is reset and the state transitions to the asynchronous state. When the device is activated, the lower layer state machine performs initialization such as waiting for information transmitted from other devices, and transitions to the asynchronous state.

In the synchronous state, from the viewpoint of synchronous continuity, the state transition operation differs depending on the state of the upper layer. In the synchronous state, if the synchronous phase becomes unstable to the extent that the synchronous accuracy requirement cannot be satisfied, or if the synchronous phase cannot be obtained due to some factor such as the inability to receive the synchronous information, and if the subsystem is referring to the timing information, the transition to the inertial synchronous state is made. At this time, the transmission of timing information continues in order to maintain synchronous continuity.

On the other hand, when the subsystem does not refer to the timing information, for example, when it does not output sound, it does not need to maintain synchronous continuity, so it resets the time synchronization control information and transitions to an asynchronous state, as in normal PTP.

In the inertial synchronization state, when the synchronization phase is stabilized enough to satisfy the synchronization accuracy requirement again, the state is changed to the synchronization state.

In this way, by performing time synchronization control according to the state machine of FIG. 5, synchronous continuity can be ensured and the subsystem can be operated stably.

Even if the subsystem refers to the timing information, it transitions to the asynchronous state by deviating from the permissible condition for synchronous continuity. This permissible condition is set by defining an abnormal state in which the subsystem cannot maintain stable operation even if synchronous continuity is ensured. For example, an abnormal state such as an unstable synchronization state lasting longer than a specified period or a synchronization phase deviation of a specified value or more is defined and set.

(semi-synchronous)
In this embodiment, the semi-synchronous processing unit 82 makes a transition to the semi-synchronous state before making a transition from the asynchronous state to the synchronous state, and makes a transition to the synchronous state when the synchronous phase is stabilized to the extent that the synchronization accuracy requirement of the subsystem that refers to the timing information is satisfied. For example, if an erroneous propagation time is obtained and synchronization control is performed to set the synchronous phase to zero, synchronous continuity cannot be maintained even if synchronization is performed with an erroneous propagation time or synchronous phase.

Immediately after the transition to the quasi-synchronization state, there is a possibility that an erroneous propagation time is obtained due to, for example, burst noise in communication of synchronization information, and an erroneous synchronization phase is calculated based on this. If a transition is made to the synchronous state as it is, the synchronous state is entered with an erroneous synchronous phase. In such a case, when the burst noise disappears, the synchronous phase is discontinuously changed to the original synchronous phase, so that synchronous continuity cannot be ensured. Once synchronized, it takes a long time to recover synchronization with the correct synchronization phase.

In order to avoid such an erroneous transition to the synchronous state, the semi-synchronous processing unit 82 assigns a weighting value according to the synchronization phase controlled by the synchronization control unit 79, and when the cumulative value of the weighting value reaches a predetermined value, the semi-synchronous state is changed to the synchronous state.

More specifically, the semi-synchronous processing unit 82 operates the processing flow shown in FIG. 6 as a function that is called every time the synchronous phase is obtained based on the propagation time in the semi-synchronous state. That is, a variable called cumulative synchronous phase is set, and processing is started each time a synchronous phase is obtained based on four propagation times, and it is determined whether or not the cumulative synchronous phase exceeds a specified value (step S101).

If the cumulative synchronous phase is equal to or less than the specified value (NO in step S101), the synchronous phase is ranked according to the value of the synchronous phase, and the weight value set according to the rank is added to the variable called the cumulative synchronous phase (steps S102 to S104, S107 to S109), and the process ends. That is, for example, zero is the value of the correct synchronization phase, values larger than zero are distinguished by ranks separated by a predetermined value width, and weights 1 to N are set in order of proximity to the correct synchronization phase for each rank.

If the accumulated synchronous phase exceeds the specified value (YES in step S101), it is determined that the synchronous phase has been obtained based on an erroneous propagation time, the accumulated synchronous phase is cleared (step S110), and the state transitions to the asynchronous state (step S111). In other words, the synchronous phase is discarded and the transition is made to the asynchronous state. When the synchronous phase zero based on the correct propagation time is obtained (NO in step S104), the accumulated synchronous phase is cleared (step S105), and the state is changed to the synchronous state (step S106).

[Synchronous phase fluctuation control]
Even if synchronization continuity is ensured by introducing the principle of synchronization state transitions, depending on the magnitude of the synchronization phase, there may be cases where subsystems that refer to timing information see that the synchronization phase has changed discontinuously. This is because the synchronous phase fluctuation speed and fluctuation acceleration change abruptly.

For example, when timing information is input to a PLL in a subsystem, sudden changes in the synchronous phase fluctuation speed and the fluctuation acceleration will cause the PLL to be unlocked if the allowable range of the input frequency fluctuation speed of the PLL is exceeded, leading to the occurrence of an abnormality in the subsystem.

In order to deal with this, it is conceivable to set an upper limit on the synchronous phase fluctuation speed and control it so that it falls within the permissible range of the subsystem. However, since the continuity of the synchronous phase fluctuation acceleration is not taken into account, there remains the possibility that it will lead to the occurrence of an abnormality in the subsystem.

In this embodiment, in addition to limiting the range of synchronous phase fluctuation speed, the synchronous phase fluctuation acceleration is configured to be a continuous function. That is, when performing synchronous control from the current synchronous phase φ _S to the target synchronous phase φ _D , for example, the synchronous phase is continuously controlled using the synchronous phase variation function f _φ (t) as shown in Equation (4), which is a sigmoid function that continues up to the second derivative.

Here, V in equation (4) is set to be a positive number equal to or less than the maximum absolute value of the synchronous phase fluctuation speed defined by the subsystem. In other words, discontinuous switching is avoided by maintaining the continuity of acceleration while limiting the speed.

Note that the synchronous phase variation function is not limited to Equation (4), and may be any function as long as the second derivative of time t is continuous and a parameter that controls the range of the first derivative can be set. Furthermore, if the subsystem allows, the computational complexity of the sync phase may be reduced by linear approximation of the sync phase variation function.

[Synchronous continuity when switching roles]
For example, when the device that was originally the master device 1a is lost and another device that was the slave device 1b becomes the master device 1a, switching between the master device 1a and the slave device 1b is performed. One of the slave devices 1b with good conditions becomes the master device 1a, and the others become the slave devices 1b again and synchronize with the master device 1a. In other words, the new master device 1a and slave device 1b are determined after the overall synchronization is reset.

In such a system in which the roles of the master device 1a and the slave device 1b are switched, it is desirable to ensure specific synchronous continuity when the roles are switched. However, in PTP, when the roles of the master device 1a and the slave device 1b are switched, the synchronous phase changes discontinuously due to the transition to the asynchronous state, so synchronous continuity cannot be ensured. Synchronous continuity in this embodiment includes the property that the subsystems that refer to the timing information operate steadily and stably when switching roles from the slave device 1b to the master device 1a.

In a system in which multiple devices of the same or similar type form a synchronous network and perform time synchronization, consider an operational case in which one of the devices dynamically operates as the master device 1a and all other devices operate as the slave devices 1b during an arbitrary period.

At this time, even if the clock performance of each device is of the same quality, there is no lack of generality. That is, from the aspect of clock performance, it can be considered that the synchronization quality will be the same regardless of which device operates as the master device 1a. Here, the synchronization quality is represented by a combination of the average value and variance of synchronization phases for a certain period of time. Furthermore, reception quality (error rate, number of missing information, etc.) such as clock quality information may be combined. If the subject is to ensure synchronous continuity when switching the role of a device, there is no problem even if a plurality of various devices form a synchronous network.

(Simultaneous startup)
FIG. 7 shows a time synchronization control state machine for ensuring synchronous continuity in each device whose role can be switched. FIG. 7 shows the state machine of the master device 1a, which is the lower hierarchy, when the slave device 1b, which is the upper hierarchy, is in the timing information reference state. In addition, in FIG. 7, the asynchronous state, semi-synchronous state, synchronous state, and inertial synchronous state are the same as above.

When the role of the own device is undetermined at the time of activation, the own device waits for the clock quality information output from the clock quality information output section 84 of the other device in an asynchronous state, but the distribution of the clock quality information is suppressed by the suppression section 86 of the own device. When the clock quality information is received within the specified period, the existing master device 1a is maintained by starting operation as the slave device 1b and transitioning to the semi-synchronous state. That is, since the own device does not distribute the clock quality information that triggers the switching of the master device 1a, the operation as the master device 1a can be continued.

The value of the ANNOUNCE packet indicates whether the device is the best master. Depending on its superiority, even if it is currently operating as the master device 1a, it will switch to the slave device 1b, and regardless of the state of the subsystem, the better device will switch to the master device 1a based on static information. Therefore, when clock quality information is distributed from its own device at startup and the master device 1a is selected by comparison with the received clock quality information, the existing master device 1a is switched to the slave device 1b, and synchronous continuity may be lost.

Therefore, in the present embodiment, the existing master device 1a is prevented from being switched to the own device based on the clock quality information of the own device by not distributing the clock quality information from the own device while waiting for the clock quality information from the other device at startup.

When the clock quality information is not received even after the specified period has passed, the clock quality information waiting is continued, each device starts transmitting the clock quality information periodically, and transitions to the quasi-time distribution state.

In the quasi-time distribution state, when the clock quality information is not received even after a specified period of time has passed, the own device starts operating as the master device 1a, starts transmitting timing information to the subsystem, and transitions to the time distribution state.

When the clock quality information is received within the specified period, the selection unit 85 compares all the received clock quality information with the clock quality information of its own device, and selects the best master device 1a. If the selected best master device 1a is its own device after the lapse of the specified period, it starts operating as the master device 1a, starts transmitting timing information to the subsystem, and transitions to the time distribution state. If the other device is the best master device 1a, the self device starts operating as the slave device 1b and transitions to the asynchronous state.

Due to this state transition, only the own device is activated independently, and when other devices are not connected to the synchronous network, it operates as the master device 1a. When the own device is connected to a synchronous network in which an already operating master device 1a exists and then starts up, the own device operates as a slave device 1b. Therefore, synchronous continuity can be maintained without carelessly switching the master device 1a in operation.

When the master device 1a of the synchronous network A is connected to the master device 1a of the synchronous network B, that is, when the synchronous network A and the synchronous network B are combined, there is no state transition in the time distribution state or the synchronous state, and the re-selection unit 87 re-selects the best master device 1a. When another device is selected as the master device 1a, it switches roles as the slave device 1b and transitions to the semi-synchronous state. Any means can be used to select the best master device 1a, but for example, PTP's BMCA (Best Master Clock Algorithm) can be used.

When the master device 1a is switched as a result of the re-election, synchronization is reestablished with the new master device 1a, but the continuity of synchronization is ensured at this time as well. That is, as described above, the synchronization phase is varied continuously. However, if there is a time difference between the master devices 1a that does not satisfy the permissible conditions of the subsystem, the continuity of synchronization may be discarded and resynchronization may be performed, or an abnormal event may be interpreted and transitioned to an abnormal state.

In addition, since the synchronous network connection between the master devices 1a in operation is hot-wired, depending on the time synchronization system, it may be interpreted as an abnormal event and transitioned to an abnormal state. Further, even after the self-device becomes the master device 1a and enters the time distribution state, the role may be switched from the master device 1a to the slave device 1b by a specific command. For example, in a synchronous network, the frequency deviation from the nominal frequency may be averaged by periodically switching the master device 1a.

(Replacement of master device)
In a single synchronization network, when the master device 1a leaves the synchronization network, or when the master device 1a changes its role to the slave device 1b, the re-election unit 87 re-selects the master device 1a, one of the slave devices 1b switches roles to the master device 1a, and the other slave devices 1b need to resynchronize with the new master device 1a. State transitions in this case will also be described according to the state machine in FIG.

When operating normally and in a synchronous state, control is performed to maintain the synchronous phase requested by the subsystem. For example, the average frequency deviation between devices is zero or near zero. Therefore, even if the master device 1a disappears for a certain period of time and the slave device 1b becomes self-running, the synchronous phase is maintained at substantially zero. Even if it takes a long time to be re-elected, it is likely that synchronization will be maintained. That is, even if a new master device 1a is elected, there is a low possibility that the synchronization phase will deviate greatly. However, in PTP, the status is changed to UNCALIBRATED, reset once, transitioned to the asynchronous status, and then synchronized again.

Here, since the self-device is synchronized with the separated old master device 1a, the synchronous phase continuously fluctuates within the synchronous phase range allowed by the subsystem even if the synchronous control is temporarily stopped. For this reason, even if the self-device regains synchronization with a different master device 1a, synchronous continuity can be ensured if state transition via an asynchronous state is not performed.

Therefore, when the clock quality information is no longer received due to the withdrawal of the master device 1a or the like, the synchronization state or the inertia synchronization state transitions to the re-election state. At this time, in order to maintain synchronous continuity, the transmission of timing information continues, and the transition to the asynchronous state does not occur.

In the re-election state, clock quality information of other devices is received, and the re-election unit 87 selects the master device 1a by means of BMCA of PTP or the like. When the own device is selected as the master device 1a, the device transits to the time distribution state. When another device is selected as the master device 1a, synchronization is reestablished with that device as the master device 1a, and the state before transitioning to the re-election state, ie, the synchronous state or the inertia synchronous state. Also at this time, in order to maintain synchronous continuity, the transmission of timing information continues and the transition to the asynchronous state does not occur.

If it takes time to select the master device 1a and the permissible conditions of the subsystem cannot be satisfied, the synchronization continuity may be abandoned and resynchronization may be performed, or an abnormal event may be interpreted and transitioned to an abnormal state.

In a synchronous network in which the synchronization phase is stable, even when the master device 1a switches roles to the slave device 1b, if it is desired to ensure synchronous continuity, the transmission of timing information is continued without resetting the time synchronization control information.

[Synchronous continuity between synchronous systems]
Like the boundary clock in the PTP system, in a synchronous repeater in which one device functions simultaneously as the master device 1a and the slave device 1b, it is desirable to ensure peculiar synchronous continuity between synchronous systems.

In the conventional synchronous repeater, the upper synchronization network and the lower synchronization network independently manage the synchronization state. For example, when the synchronous relay device is activated, the master device 1a and the slave device 1b are activated simultaneously, and each performs synchronous control independently. Therefore, the slave device 1b must synchronize with the master device 1a, which takes time.

In other words, the boundary clock functions as the master device 1a for the lower synchronization system. Since the master device 1a has already established its status as the master device 1a, it is sufficient to send an ANNOUNCE packet or the like to synchronize the lower synchronization network. When the boundary clock is activated in this manner, the synchronous phase of the lower synchronous network system is determined by the function as the master device 1a. On the other hand, since it is necessary for the slave device 1b to determine the synchronous phase with respect to the master of the upper synchronous network on the side closer to the grandmaster clock, it takes time to determine.

However, the synchronization information transmitted to the lower synchronization network is generated based on the timing information of the upper synchronization network. Therefore, if the lower synchronization network determines the synchronization state first, the synchronization phase of the lower synchronization network becomes discontinuous in the process of determining the synchronization state of the higher synchronization network, and there is a possibility that the synchronization continuity cannot be maintained in the lower synchronization network.

Therefore, the information communication device 1 serving as a synchronous repeater manages the synchronization state in cooperation with the synchronization networks, suspends the transmission of timing information to the lower synchronization network, and suspends the distribution of the clock quality information and the synchronization information in the lower synchronization network until the synchronization state of the upper synchronization network is determined. That is, after synchronization is established in the upper synchronization network by the slave device 1b of the synchronization relay device, the master device 1a of the synchronization relay device controls synchronization in the lower synchronization network by transmitting synchronized timing information to the lower synchronization network. As a result, in the master device 1a connected to the lower synchronous network, the f-phase fluctuation is eliminated and synchronous continuity is ensured.

[Election of preemptive master device]
As described above, by maintaining synchronous continuity when the slave device 1b and the master device 1a switch roles, each slave device 1b can maintain synchronous continuity even when a plurality of information communication devices 1 dynamically and repeatedly elect the master device 1a in a single synchronous network.

However, since the method of replacing the master device 1a is arbitrary, the time required for this replacement cannot be controlled and is unstable. Therefore, there is a possibility that the permissible condition of the subsystem cannot be satisfied and transition to resynchronization or an abnormal state occurs. Furthermore, since the clock quality information is not distributed during the specified period immediately after the slave device 1b is activated or immediately after the transition to the asynchronous state, it takes time to select the master device 1a.

In order to deal with this, the present embodiment has a selection function based on some master device selection principles instead of selecting the master device 1a based on the clock quality information described above. Here, these principles are integrated and called PMCA (Preemptive Master Clock Algorithm).

(priority information)
In the selection of the master device 1a by BMCA of PTP, clock quality information (each element of the ANNOUNCE packet), which is static information, is delivered immediately after the information communication device 1 is activated. Therefore, depending on the order of static information such as MAC addresses, there is a possibility that a device that is later connected to the synchronous network will become the master device 1a, and that the role of the existing master device 1a will be switched to the slave device 1b, making it impossible to maintain synchronous continuity.

As described above, if the device whose role is undetermined does not distribute the clock quality information immediately after activation, the device will not become the master device 1a in place of the existing master device 1a due to the BMCA. However, even in this case, the slave device 1b waits for reception of clock quality information from the other device and starts operating as the slave device 1b based on the received clock quality information. Also, when the master device 1a is lost and the master device 1a is not determined between the previously connected devices at the time of starting the own device, it is necessary to wait for the clock quality information from the other device and determine the role. In that case, the role is determined according to the static order of the clock quality information, so the time required for determining the role becomes longer.

In order to deal with this, the present embodiment periodically distributes priority order information including dynamically updatable elements immediately after the information communication device 1 is activated. This information may be added as a new element to the clock quality information, or may dynamically update an existing element. Simultaneously with the distribution of the priority information, the priority information distributed by the other information communication device 1 is awaited. The priority information includes an element that can identify the distribution device.

(preemption of master device)
The role determination unit 88 determines the master device 1a based on this priority order information. This is a process in which the information communication device 1 to be connected later does not take over as the master device 1a, that is, the device that is activated first preempts the role of the master device 1a. This processing flow is shown in FIG.

In the processing flow of FIG. 8, the information communication device 1 sets the priority of its own device to low in the priority information immediately after activation, that is, in an asynchronous state (step S201). If the role of the own device is undecided (step S202), priority information is distributed (step S203).

If no priority information is received from the other device (NO in step S204) and the prescribed period has passed (YES in step S205), the device determines its role as the master device 1a, updates its priority to a high level, and distributes the priority information (step S206). Then, if the priority order information of the other device is not received (NO in step S207), it operates as the master device 1a. If the priority order information of the other device is received (YES in step S207) and the priority order of the other device is lower than that of the own device (NO in step S208), it operates as the master device 1a. If the priority of the other device is equal to or higher than the own device (YES in step S208), the master device 1a is re-elected or processed as an abnormal event (step S209).

In step S202, even in the case of the information communication device 1 already operating as the master device 1a, it operates as the master device 1a without distributing the priority information (step S206), and proceeds to the processing after step S207. In other words, when the role of the own device as the master device 1a is determined, it can be interpreted that the synchronous networks each having the master device 1a are hot-plugged, so the master device 1a may be re-elected or handled as an abnormal event.

When re-electing the master device 1a, an attempt is made to maintain synchronous continuity. When handled as an abnormal event, it transitions to an abnormal state. This is similar to the case of simultaneous activation of synchronous continuity when switching roles.

When the priority information is received from the other device (YES in step S204) and the priority of the other device is higher than that of the own device (NO in step S210), the role as the slave device 1b is determined and the distribution of the priority information is stopped (step S211). If the priority of the other device is equal to or lower than the own device (YES in step S210), after a predetermined period of time has passed (YES in step S205), the device operates as the master device 1a (step S206), and proceeds to the processing after step S207.

Also, in the case of the information communication device 1 already operating as the slave device 1b (step S202), it operates as the slave device 1b without distributing the priority order information (step S211).

As described above, by using the dynamic priority order information, it is possible to prevent the information communication device 1 to be connected later from being replaced by the master device 1a when the device that is activated first assumes the role of the master device 1a in advance and there is already an information communication device 1 operating as the master device 1a.

(generate master ranking list)
As described above, the priority information allows the master device 1a to be determined quickly, and the master device 1a to be stabilized against device connection to the synchronous network. However, when the master device 1a leaves the synchronous network or changes its role to the slave device 1b, it is necessary to select a new master device 1a from the remaining slave devices 1b.

For example, in the selection of the master device 1a by BMCA of PTP, all the slave devices 1b are candidates for the master device 1a. For this reason, a plurality of information transmission sequences occur, and there is a possibility that the master device 1a cannot be selected by distributing the clock quality information once, and it takes a considerable amount of time to complete the selection.

In addition, since the frequency deviation between devices (between clocks) fluctuates non-linearly in time series, it is difficult to predict it. Furthermore, in a time synchronization system, the environment (ambient temperature, acceleration, electromagnetic field) in which each device is placed is generally independent and not the same. Therefore, the best master device selection means that compares static characteristics such as the nominal accuracy of the clock may not dynamically select the best master device 1a.

In order to cope with this, in the present embodiment, as shown in the sequence diagram of FIG. 9, the order list generation unit 89 generates the master order list by receiving the synchronization quality information of the slave device 1b. In FIG. 9, a plurality of slave devices 1b are indicated by (1, 2, 3, . . . , N). Each slave device 1b performs synchronization control by receiving clock quality information and synchronization information transmitted from the master device 1a, and calculates synchronization quality.

Each slave device 1b periodically transmits current synchronization quality information to the master device 1a. At this time, a new telegram may be defined and transmitted, or synchronization quality may be added to the telegram used for time synchronization control.

Upon receiving the synchronization quality information from each slave device 1b, the master device 1a ranks the synchronization quality and periodically obtains the ranking of the slave device 1b whose role should be switched to the master device 1a. That is, the order in which each slave device 1b is selected as the master device 1a is determined.

When ranking the slave devices 1b, from the viewpoint of short-term stability, the variance of the synchronization phase of the synchronization quality may be arranged in ascending order, or the error rate and the number of missing pieces of the communicated information may be arranged in ascending order. Also, statistics may be collected for all slave devices 1b with respect to the average synchronization phase of synchronization quality, and slave devices 1b having outliers may be excluded from the ranking. From the viewpoint of long-term stability, the average synchronization phase of synchronization quality may be sequentially statistically collected for each slave device 1b, and the variances may be arranged in ascending order. This ranking can be said to be dynamic information that changes over time.

The ranking list generator 89 creates a master ranking list from the ranking of the slave device 1b and the identification information of the slave device 1b. The master ranking list may be in a complete format in which all slave devices 1b are ranked, or may be in a partial format in which only the top or a few top items are listed.

(Distribution of master ranking list)
The master device 1a periodically distributes the master ranking list to each slave device 1b.
The slave device 1b receives and stores the master order list. Also, each time the master ranking list is received, the elapsed time from the reception is measured. Also, upon receiving the master ranking list, the presence information delivery unit 90 of the slave device 1b at the top or several of the top slave devices 1b delivers presence information indicating that it is connected to the synchronous network. This presence information may be substituted by information necessary for time synchronization control.

When the master device 1a withdraws from the synchronous network or changes its role to the slave device 1b, it delivers a withdrawal declaration to the slave device 1b. A withdrawal declaration may include a master ranking list.

The master determination unit 91 of the slave device 1b that has received the withdrawal declaration determines the slave device 1b at the top of the list connected to the synchronization network as the new master device 1a from the latest master order list and presence information. The determined slave device 1b switches roles to the master device 1a, and the other slave devices 1b switch time synchronization control to the new master device 1a. At this time, too, an attempt is made to maintain synchronous continuity. After that, in the new master device 1a and slave device 1b, the synchronization quality is calculated, the master ranking list is generated, and the presence information is distributed in the same manner as described above.

When a withdrawal declaration is not received from the master device 1a and information such as a master order list cannot be received for a prescribed period, the master device 1a is interpreted as being withdrawn from the synchronous network, and each slave device 1b replaces the master device 1a in the same manner as when receiving the withdrawal declaration. At this time, too, an attempt is made to maintain synchronous continuity.

When the master device 1a is replaced, if the information to be distributed from the new master device 1a cannot be received for a prescribed period, the second slave device 1b in the master ranking list connected to the synchronous network may be reselected as the master device 1a. The operation of reselecting the slave device 1b of the lower order as the master device 1a may be repeated until the replacement of the master device 1a is completed.

If the replacement of the master device 1a using the master order list fails, all the slave devices 1b may distribute the synchronization quality to each other, and the slave device 1b with the highest synchronization quality may be selected as the master device 1a, or conventional master device selection means such as BMCA of PTP may be taken.

[effect]
(1) The present embodiment is an information communication system 100 in which a plurality of information communication devices 1 perform information communication as a master device 1a or a slave device 1b. The information includes synchronization information, which is information communicated for synchronizing time between the master device 1a and the slave device 1b, and priority information including information indicating whether the possibility of being selected as the master device 1a is high or low.

In addition, the present embodiment includes a synchronization control unit 79 that controls the synchronization phase between the master device 1a and the slave device 1b based on synchronization information so as to achieve a synchronized state in which time is synchronized, a timing information reference unit 80 that performs processing in synchronization with the timing information by referring to the timing information indicating the synchronized timing output from the synchronization control unit 79, and a transition from the synchronized state to the asynchronous state in which synchronization is lost based on the synchronization phase while the timing information reference unit 80 is performing synchronized processing when a factor that causes loss of synchronization occurs. and an inertial synchronization processing unit 81 that suspends transition and transitions to an inertial synchronization state that maintains continuous synchronization.

Further, this embodiment has a role determination unit 88 that determines the role of the information communication device 1 whose role is undetermined based on the priority information transmitted to the other information communication device 1 by the information communication device 1 whose role is undetermined as the master device 1a and the slave device 1b, and the priority information received from the other information communication device 1 when the information communication device 1 whose role is undetermined as the master device 1a and the slave device 1b is activated.

Further, the present embodiment is an information communication device 1 that performs information communication with another information communication device 1 in the role of a master device 1a or a slave device 1b, and includes a synchronization control unit 79 that synchronizes time with the other information communication device 1 by controlling the synchronization phase based on synchronization information, a timing information reference unit 80 that refers to timing information indicating a synchronized timing output from the synchronization control unit 79 and performs processing in synchronization with the timing information, and a timing information reference unit 80 that performs processing in synchronization with the timing information when a factor that causes synchronization to be lost occurs. and an inertial synchronization processing unit 81 that suspends the transition from the synchronous state to the asynchronous state that loses synchronization and transitions to the inertial synchronous state that maintains continuous synchronization based on the synchronous phase while the synchronous processing is performed.

Further, the information communication device 1 of the present embodiment has a role determination unit 88 that determines the role of the information communication device 1 whose role is undetermined based on the priority information transmitted by the information communication device 1 whose role is undetermined to other information communication devices 1 as a low-ranked information communication device 1 and the priority information received from the other information communication device 1 when the information communication device 1 whose role is undetermined as the master device 1a and the slave device 1b is activated.

In this way, even if a factor that causes loss of synchronization occurs in the synchronous state while the timing information reference unit 80 is performing synchronous processing, the inertial synchronous processing unit 81 makes a transition to the inertial synchronous state according to the synchronous phase, thereby suspending the transition to the asynchronous state and maintaining continuous synchronism. Therefore, it is possible to reduce the situation in which the operation quality is lowered, such as the occurrence of phase noise in the voice and the interruption of the voice, due to discontinuous synchronization.

Also, the master device 1a can be determined based on the order of connection to the information communication system 100 based on dynamically generated priority information rather than referring to static characteristic information such as clock quality information unique to the device. Since the master device 1a can be quickly determined in advance in this manner, the possibility of transition to an asynchronous state can be reduced, and discontinuous synchronous phase changes at the time of switching of the master device 1a by BMCA can be suppressed.

(2) A ranking list generator 89 that generates a master ranking list indicating the order in which the slave devices 1b are selected as the master device 1a based on synchronization quality information from a plurality of slave devices 1b; a presence information distribution module 90 that distributes presence information indicating that each slave device 1b that has received the master ranking list is connected to the information communication system 100; and a master determination unit 91 that determines the slave device 1b to be set to a.

Therefore, when the master device 1a withdraws from the information communication system 100 or changes its role to the slave device 1b, when selecting a new master device 1a from among the remaining slave devices 1b, the master device 1a can be quickly determined based on the dynamically generated master order list, not by referring to the static characteristic information. Therefore, it is possible to reduce the possibility of transition to the asynchronous state, and suppress discontinuous changes in the synchronization phase when the master device 1a is switched by the BMCA.

(3) In the asynchronous state, the synchronous control section 79 starts synchronous control until a predetermined synchronous phase is reached, and the quasi-synchronous processing section 82 puts the transition to the synchronous state into a quasi-synchronous state. Therefore, since the synchronous state can be set after the synchronous phase is stabilized, it is possible to reduce the possibility of discontinuous switching of the synchronous phase due to an erroneous propagation time and the synchronous phase based thereon.

(4) It has a variation control section 83 that limits the speed of the synchronous phase change for synchronization within a predetermined range and controls the acceleration of the synchronous phase change to fluctuate according to a continuous function. Therefore, it is possible to prevent a situation in which an abnormality occurs due to the fluctuation speed and the fluctuation acceleration exceeding the allowable range of the apparatus.

(5) A clock quality information output unit 84 that outputs clock quality information, a selection unit 85 that selects one of the information communication devices 1 as at least one of the master device 1a and the slave device 1b based on the clock quality information, and a suppression unit 86 that suppresses switching of the existing master device 1a to the slave device 1b due to selection by the selection unit 85 by suspending the output of the clock quality information to the clock quality information output unit 84 of the information communication device 1 at startup. Therefore, even if there is an information communication device 1 newly connected to the system, the existing master device 1a is more likely to maintain its status as a master, and the possibility of loss of synchronous continuity can be reduced.

(6) When the slave device 1b detects that the master device 1a has left the information communication system 100, it has a re-election unit 87 that transitions from the synchronization state or the inertial synchronization state to a re-election state in which any information communication device 1 is re-elected as the master device 1a. Therefore, when the master device 1a is re-elected, the synchronous state or the inertial synchronous state is maintained, so that the possibility of maintaining the continuity of synchronization can be increased.

(7) Any of the information communication devices 1 includes an information communication device 1 that functions as a synchronization relay device having the functions of both the master device 1a and the slave device 1b, and when the slave device 1b side is an upper synchronization network and the master device 1a side is a lower synchronization network, after the slave device 1b establishes synchronization in the upper synchronization network, the master device 1a controls synchronization in the lower synchronization network by transmitting synchronized timing information to the lower synchronization network. Therefore, after the lower synchronization network first establishes synchronization, the lower synchronization network establishes synchronization again according to the synchronization established by the upper synchronization network, thereby reducing the possibility of loss of synchronization continuity.

[Other embodiments]
The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the present invention at the implementation stage. Also, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments.

1 information communication device 1a master device 1b slave device 10 communication unit 11 transmitter 12 receiver 13 transmission timing detection unit 14 reception timing detection unit 20 clock 30 clock 50 storage unit 60 external interface 70 control unit 71 main control unit 72 transmission/reception data I/F
73 communication control unit 74 time recording unit 77 scheduler 78 frequency deviation calculation unit 79 synchronization control unit 80 timing information reference unit 81 inertial synchronization processing unit 82 semi-synchronization processing unit 83 fluctuation control unit 84 clock quality information output unit 85 selection unit 86 suppression unit 87 re-selection unit 88 role determination unit 89 order list generation unit 90 presence information distribution unit 91 master determination unit 100 information communication system

Claims (4)

An information communication device that communicates information with other information communication devices in the role of a master device or a slave device , and in which a synchronous network is formed by a plurality of information communication devices of the same or similar type ,
The information includes synchronization information for synchronizing time with other information communication devices and priority information including information on whether the possibility of being selected as a master device is high or low,
a synchronization control unit that establishes a synchronized state by controlling a synchronization phase with another information communication device based on the synchronization information;
a timing information reference unit that refers to timing information indicating synchronized timing output from the synchronization control unit and performs processing in synchronization with the timing information;
an inertial synchronization processing unit that suspends the transition from the synchronous state to the asynchronous state that loses synchronization based on the synchronous phase and transitions to the inertial synchronous state that maintains continuous synchronism, while the timing information reference unit is performing processing synchronous with the timing information when a factor causing the loss of synchronism occurs;
a role determination unit that, when an information communication device whose roles as a master device and a slave device are undetermined is activated, determines the role of its own device based on priority information that the information communication device whose role is undetermined transmits to other information communication devices as a low-level information communication device and priority information that is received from the other information communication device;
a ranking list generator for generating a master ranking list indicating the ranking in which slave devices are selected as master devices based on synchronization quality information from a plurality of slave devices;
a presence information distribution unit that distributes presence information indicating that each slave device that has received the master order list is connected to the synchronization network of the slave device;
a master determination unit that determines a slave device to be a new master device based on the master order list and the presence information when the master device leaves the synchronization network;
An information communication device comprising: 2. The information communication device according to claim 1 , further comprising a semi-synchronous processing unit that suspends a transition to said synchronous state until a predetermined synchronous phase is reached after synchronous control by said synchronous control unit is started in said asynchronous state. 3. The information communication device according to claim 1, further comprising a variation control section for limiting the speed of the synchronization phase change for synchronization within a predetermined range and controlling the acceleration of the synchronization phase change to vary according to a continuous function. 4. An information communication system comprising a plurality of information communication devices according to any one of claims 1 to 3, wherein the information communication device acting as the slave device is synchronized with the information communication device acting as the master device.

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