JP2012114815A - Phase synchronization device and phase synchronization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase synchronization device capable of phase synchronization between devices connected through a radio line.SOLUTION: A master side radio device 3 extracts timing to be a reference of phase synchronization from a reception packet from a master device 1, determines the timing of transmitting the packet to a slave side radio device 4 in synchronism with the timing to be the reference, and transmits the reception packet to the slave side radio device 4. The slave side radio device 4 extracts the timing to be the reference of the phase synchronization from the reception packet from the master side radio device 3, detects a frequency deviation on the basis of a phase difference detected by comparing the extracted timing with operation timing within the present device, controls the frequency of the operation clock within the present device on the basis of the phase difference and the frequency deviation, determines the timing of transmitting the packet to a slave device 2 in synchronism with the timing to be the reference, and transmits the reception packet to the slave device 2.

Description

  The present invention relates to a phase synchronization apparatus that performs phase synchronization between two apparatuses that perform packet communication.

  In a conventional wireless transmission system, when performing phase synchronization for matching the operation cycle between devices connected via a wireless line, the receiving device sets the reception interval of packets transmitted from the transmitting device at regular time intervals. Based on the fluctuation of the reception interval, the frequency of the oscillator that generates the operation clock is controlled to synchronize the reception device side time with the transmission device side time. Such a technique is disclosed in Patent Document 1 below.

  In general, in wireless transmission, it is known that there are cases in which a reception error occurs due to temporal fluctuations in radio wave propagation and packets cannot be received normally. When a reception error occurs, the transmission apparatus retransmits the same packet that has caused the reception error, thereby preventing packet loss in wireless transmission. At this time, the delay until the receiving apparatus receives the packet increases by the amount of retransmission.

  Even when retransmission does not occur, for example, in a wireless LAN (Local Area Network) defined by IEEE 802.11, when a radio wave transmitted by another device is detected when transmitting a packet, After this radio wave disappears, transmission is started after waiting for a time called back-off calculated using a random number every time a packet is further transmitted. Therefore, the packet delay is increased by the time when the other devices are transmitting and the total time of the backoff. Thus, in wireless transmission, the delay increases or decreases each time a packet is transferred. Hereinafter, the increase / decrease in delay in the packet transfer is referred to as delay fluctuation.

JP 2004-350102 A

  However, according to the above conventional technique, the frequency of the oscillator that generates the operation clock is controlled based on the fluctuation of the reception interval of the packets transmitted at regular time intervals. Therefore, when packet delay fluctuation occurs due to packet retransmission or transmission from another device, a phase shift occurs according to the amount of delay of the received packet between the transmission device and the reception device, and it operates normally. There was a problem that it was impossible.

  As a method for avoiding such a problem, common time information is externally transmitted to both the transmission device and the reception device by using a known technique such as GPS (Global Positioning System) or NTP (Network Time Protocol). It is also possible to perform phase synchronization by supplying. However, GPS has a problem that it cannot be used in places where it is difficult to receive GPS radio waves such as indoors. In addition, in NTP, it is necessary to additionally install an NTP server that supplies time information, and there is a problem in that equipment costs and management costs as a system increase.

  The present invention has been made in view of the above, and provides a phase synchronization apparatus capable of performing phase synchronization between apparatuses connected via a wireless line without requiring time information from the outside. The purpose is to obtain.

  In order to solve the above-described problems and achieve the object, the present invention is inserted between a master device and a slave device sharing an operation cycle in a master-slave relationship, and between the two devices via a wireless line. A phase synchronization device that establishes phase synchronization, wherein the phase synchronization device includes a master side wireless device that performs phase synchronization with the master device, and a slave side wireless device that supplies synchronization timing to the slave device, The master-side radio apparatus includes a first synchronization timing extraction unit that extracts a timing that is a reference for phase synchronization from a packet received from the master apparatus, and the slave-side radio apparatus that is synchronized with the reference timing. First operation timing generation means for determining the timing of transmitting a packet to the received packet at the determined timing First packet transmitting means for transmitting to the radio device on the slave side, wherein the slave radio device extracts a second timing that is a reference for phase synchronization from the packet received from the master radio device Synchronization timing extraction means, a phase difference detection means for detecting the phase difference by comparing the extracted timing with the operation timing in the apparatus, and a frequency deviation detection for detecting a frequency deviation based on the phase difference Means, clock frequency control means for controlling the frequency of the operation clock in the own apparatus based on the phase difference and the frequency deviation, and timing for transmitting the packet to the slave apparatus in synchronization with the reference timing. A second operation timing generation means for determining, and a packet received at the determined timing directed to the slave device Characterized in that it comprises a second packet transmission means for transmitting, the.

  According to the present invention, there is an effect that phase synchronization between devices connected via a wireless line can be performed without requiring time information from the outside.

FIG. 1 is a diagram illustrating a configuration example of a communication system to which a phase synchronization apparatus is applied. FIG. 2 is a diagram illustrating a configuration example of the master-side wireless device. FIG. 3 is a diagram illustrating a configuration example of the slave-side wireless device. FIG. 4 is a flowchart showing the phase synchronization operation. FIG. 5 is a diagram illustrating the phase synchronization operation of the slave-side wireless device. FIG. 6 is a diagram illustrating the phase synchronization operation of the slave-side wireless device. FIG. 7 is a diagram illustrating the phase synchronization operation of the slave-side wireless device. FIG. 8 is a diagram illustrating a configuration example of the slave-side wireless device. FIG. 9 is a diagram illustrating a configuration example of the slave-side wireless device.

  Embodiments of a phase synchronization apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a communication system to which the phase synchronization apparatus according to the present embodiment is applied. The communication system includes a master device 1, a slave device 2, a master side wireless device 3, and a slave side wireless device 4. The master device 1 and the master side wireless device 3 are connected by a wired line 10, the master side wireless device 3 and the slave side wireless device 4 are connected by a wireless line 20, and the slave side wireless device 4 and the slave device 2 are connected by a wired line 11. It is connected. The two devices, the master side wireless device 3 and the slave side wireless device 4, constitute a phase synchronization device.

  The master device 1 is connected to the wired line 10 and transmits a wired packet to the master-side wireless device 3 via the wired line 10 based on an operation cycle generated in the own device.

  The slave device 2 is connected to the wired line 11 and generates an operation cycle within the own device based on the reception timing of the wired packet received from the slave-side wireless device 4 via the wired line 11.

  Originally, the master device 1 and the slave device 2 are directly connected via a wired line, and the slave device 2 operates so as to share an operation cycle in a relationship subordinate to the master device 1. In particular, in an FA (Factory Automation) control device that requires high reliability, high accuracy is required even in the sharing of the operation cycle (that is, phase synchronization).

  The master-side wireless device 3 is connected to the wired line 10 and the wireless line 20, extracts the synchronization timing based on the reception timing of the wired packet received from the master device 1 via the wired line 10, and synchronizes with this synchronization timing. The wireless packet is transmitted to the slave side wireless device 4 via the wireless line 20.

  The slave-side wireless device 4 is connected to the wired line 11 and the wireless line 20, extracts the synchronization timing based on the reception timing of the wireless packet received from the master-side wireless device 3 via the wireless line 20, and uses this synchronization timing. Synchronously, the wired packet is transmitted to the slave device 2 via the wired line 11.

  Next, the master side radio apparatus 3 constituting the phase synchronization apparatus will be described in detail. FIG. 2 is a diagram illustrating a configuration example of the master-side wireless device 3. The master-side wireless device 3 includes a wired packet receiver 30, a synchronization timing extractor 31, an operation clock generator 32, an operation timing generator 33, and a wireless packet transmitter 34.

  The wired packet receiving unit 30 receives a packet transferred on the wired line 10, removes header information added for transferring on the wired line 10, and outputs it to the apparatus.

  The synchronization timing extraction unit 31 stores the reception timing of the packet received by the wired packet reception unit 30. Further, a common cycle is detected from the stored reception timing and output as a synchronization timing signal.

  The operation clock generation unit 32 generates a clock signal necessary for each unit in the own device to operate.

  The operation timing generation unit 33 operates with the clock signal from the operation clock generation unit 32, determines a timing for transmitting a radio packet to the radio line 20 using the synchronization timing signal, and generates a radio transmission timing signal.

  The wireless packet transmitter 34 transmits the packet output from the wired packet receiver 30 to the wireless line 20 in accordance with the wireless transmission timing signal from the operation timing generator 33. Here, the synchronization timing extraction unit 31 detects a common cycle from the reception timing by any of the following methods, for example.

  1. The type of packet that is periodically transmitted is determined from the received packets, and only the reception timing is extracted.

  2. A period common to all packets is detected. For example, if all packets are transmitted according to the rule that if there is a packet to be transmitted at a certain time interval and not transmitted if there is no packet to be transmitted, the minimum value of the reception timing is set to all packets. A common cycle.

  Next, the slave side wireless device 4 constituting the phase synchronization device will be described in detail. FIG. 3 is a diagram illustrating a configuration example of the slave-side wireless device 4. The slave-side radio apparatus 4 includes a radio packet receiver 40, a synchronization timing extractor 41, an operation clock generator 42, an operation timing generator 43, a wired packet transmitter 44, a phase difference detector 45, a frequency A deviation detection unit 46 and a clock frequency control unit 47 are provided.

  The wireless packet receiving unit 40 receives a packet transferred from the wireless line 20, removes header information added for transferring on the wireless line 20, and outputs it to the apparatus.

  The synchronization timing extraction unit 41 stores the reception timing of the packet received by the wireless packet reception unit 40. Also, delay fluctuations in wireless transmission are detected for each of the stored reception timings, and the average value is calculated for each fixed number to average the delay fluctuations and store them as average reception timings. A common cycle is detected from the timing and output as a synchronization timing signal.

  The operation clock generation unit 42 generates a clock signal necessary for each unit in the device to operate, and changes the frequency of the clock signal according to the input frequency control signal.

  The operation timing generation unit 43 operates with the clock signal from the operation clock generation unit 42, determines the timing for transmitting a wired packet to the wired line 11, generates a wired transmission timing signal, and compares it with the synchronization timing signal. A timing signal for comparison is generated.

  The wired packet transmission unit 44 transmits the packet output from the wireless packet reception unit 40 to the wired line 11 according to the wired transmission timing signal from the operation timing generation unit 43.

  The phase difference detection unit 45 compares the synchronization timing signal generated by the synchronization timing extraction unit 41 with the comparison timing signal generated by the operation timing generation unit 43, so that the master-side radio apparatus 3 and its own apparatus are compared. The difference in the operation period, that is, the phase difference between devices is detected and output as phase difference information.

  The frequency deviation detector 46 monitors the phase difference at a constant period, and detects the frequency deviation of the operation clock in the own apparatus relative to the master side radio apparatus 3 from the temporal variation of the phase difference.

  Based on the phase difference information output from the phase difference detection unit 45 and the frequency deviation value detected by the frequency deviation detection unit 46, the clock frequency control unit 47 determines the phase difference between the master side radio apparatus 3 and the own apparatus. A frequency control signal to be output to the operation clock generation unit 42 is generated so as to control the operation clock frequency so as to be a value (for example, 0). Here, the synchronization timing extraction unit 41 detects a common cycle from the average reception timing, for example, by any of the following methods. This is the same as the synchronization timing extraction unit 31 of the master side wireless device 3 described above.

  1. The type of packet that is periodically transmitted is determined from the received packets, and only the reception timing is extracted.

  2. A period common to all packets is detected. For example, if all packets are transmitted according to the rule that if there is a packet to be transmitted at a certain time interval and not transmitted if there is no packet to be transmitted, the minimum value of the reception timing is set to all packets. A common cycle is used.

  Next, the phase synchronization operation in the phase synchronization apparatus will be described. FIG. 4 is a flowchart showing a phase synchronization operation in the phase synchronization apparatus. First, in the master-side wireless device 3, the synchronization timing extraction unit 31 detects a common period from the reception timing of the packet received by the wired packet reception unit 30, and extracts a timing that is a reference for phase synchronization (step) S1).

  Next, the operation timing generation unit 33 operates with the clock signal from the operation clock generation unit 32, and determines the timing for transmitting a packet to the slave-side wireless device 4 in synchronization with the extracted timing (step S2).

  Then, the wireless packet transmitter 34 transmits the packet output from the wired packet receiver 30 to the slave-side wireless device 4 at the timing determined by the operation timing generator 33 (step S3).

  FIG. 5 is a diagram illustrating the phase synchronization operation of the slave-side wireless device 4. The state of the temporal change of the phase difference between the master side radio apparatus 3 and the slave side radio apparatus 4 is shown. In FIG. 5, in the slave-side wireless device 4, the synchronization timing extraction unit 41 detects a common period from the reception timing of the packet received by the wireless packet reception unit 40 and extracts a timing that is a reference for phase synchronization. (Step S4). Specifically, the synchronization timing extraction unit 41 calculates an average value for each fixed number for each reception timing of each packet.

  Next, the phase difference detection unit 45 detects the phase difference by comparing the extracted timing with the operation timing in the own apparatus (step S5). Specifically, the phase difference detection unit 45 detects that the phase difference between the master side wireless device 3 has changed from Δt1 to Δtn from time T1 to time T2.

  Next, the frequency deviation detector 46 detects the frequency deviation based on the detected phase difference (step S6). Specifically, the frequency deviation detection unit 46 monitors the phase difference information output from the phase difference detection unit 45 at a constant cycle (hereinafter referred to as a synchronization cycle), and the time from time T1 to time T2 Based on the phase difference fluctuation amount (Δtn−Δt1) in the phase monitoring time corresponding to, the frequency deviation Δf at time T2 is calculated by the following equation (1).

  Frequency deviation (Δf) at T2 = phase difference fluctuation amount (Δtn−Δt1) / phase monitoring time (T2−T1) (1)

  Next, the clock frequency control unit 47 controls the frequency of the operation clock in its own device based on the phase difference and the frequency deviation (step S7). Specifically, the clock frequency control unit 47 uses the phase difference Δtn and the frequency deviation Δf at time T2 to obtain a desired phase difference (for example, 0) with a phase control time corresponding to the time from time T2 to time T3. The frequency control amount for controlling the operation clock frequency is determined so as to be. At this time, a phase difference correction amount for obtaining a desired phase difference (here, a numerical value for changing the phase difference in a direction in which the change in the phase difference with the master-side wireless device 3 becomes a positive value) When the desired phase difference is set to 0, the relationship between the phase difference correction amount is −Δtn) and the frequency control amount is expressed by the following equation (2).

  Frequency control amount at T2 = phase difference correction amount / phase control time (T3-T2) −Δf (2)

  Next, the operation timing generation unit 43 determines the timing for transmitting a packet to the slave device 2 in synchronization with the extracted reference timing (step S8).

  Then, the wired packet transmitter 44 transmits the packet received by the wireless packet receiver 40 toward the slave device 2 at the timing determined by the operation timing generator 43 (step S9). Thus, in the slave side radio | wireless apparatus 4, a phase difference is corrected for every synchronization period which consists of phase monitoring time and phase control time.

  As described above, in the present embodiment, in the phase synchronization apparatus including the master side radio apparatus 3 and the slave side radio apparatus 4, the master side radio apparatus 3 is wirelessly synchronized in phase with the operation cycle of the master apparatus 1. The slave side wireless device 4 transmits the packet, averages the delay fluctuations of the wireless packet in the wireless line 20 to determine the synchronization timing, detects the phase difference and the frequency deviation with the master side wireless device 3, and detects a desired value. The operation clock is controlled so as to achieve a phase difference. Thereby, the wired packet can be transmitted to the slave device 2 in phase synchronization with the operation cycle of the master-side wireless device 3, and the master device 1 and the slave device 2 can be phase-synchronized via the wireless line 20.

  Moreover, by detecting not only the phase difference but also the frequency deviation at the same time, it is possible to handle not only the direction of controlling the frequency of the operation clock but also the control amount, and the phase control time (time until the desired phase difference is reached). ) Can be adjusted. This makes it possible to adjust the phase control time and the frequency control amount flexibly according to changes in the situation such as system requirements, usage conditions, and environmental fluctuations.

  Further, by controlling the frequency of the operation clock instead of directly controlling the phase, it is possible to prevent sudden phase fluctuations and changes in the number of operation clocks in the slave side wireless device 4. As a result, it is possible to apply the present invention to a system having a severe requirement for phase fluctuation that causes a malfunction of the apparatus when there is a large phase fluctuation.

Embodiment 2. FIG.
In the first embodiment, as the phase synchronization operation in the slave-side wireless device 4, the phase monitoring time in which only the phase difference is monitored without performing phase control, and the phase control in which only the phase control is performed without monitoring the phase difference The time was divided and operated in the synchronization cycle. In this embodiment, phase difference monitoring and phase control are performed simultaneously. A different part from Embodiment 1 is demonstrated.

  FIG. 6 is a diagram illustrating the phase synchronization operation of the slave-side wireless device 4 in the present embodiment. In the slave side wireless device 4, the phase monitoring time, the phase control time, and the synchronization period are all set to the same value, and the phase difference change state when the phase difference monitoring and the phase control are performed simultaneously is shown. is there. In the phase synchronization operation, one phase is completed by monitoring the phase difference in a certain synchronization period and performing phase control in the next synchronization period. In this embodiment, the phase difference monitoring and the phase control are performed simultaneously when the phase difference is monitored in a certain synchronization cycle and the phase control is performed in the next synchronization cycle. Is to monitor the phase difference. FIG. 6 describes only one cycle of the phase synchronization operation.

  In FIG. 6, the slave side wireless device 4 calculates an average value for each of the reception timings of the individual packets by the synchronization timing extraction unit 41 for each fixed number, and the phase difference detection unit 45 from the time T1 to the time T2. It is detected that the phase difference with the master side wireless device 3 has changed from Δt1 to Δtn. The frequency deviation detector 46 monitors the phase difference information output from the phase difference detector 45 in the synchronization cycle, and the phase monitoring time corresponding to the time from time T1 to time T2 (in this case, the phase control time) The frequency deviation Δf at time T2 is calculated by the following equation (3) from the phase difference fluctuation amount (Δtn−Δt1) in the same period as the synchronization period).

  Frequency deviation (Δf) at T2 = phase difference fluctuation amount (Δtn−Δt1) / synchronization cycle (3)

  Next, the clock frequency control unit 47 controls the operation clock frequency from the phase difference Δtn and the frequency deviation Δf at time T2 so that a desired phase difference (for example, 0) is obtained at the same time as the next synchronization cycle. The amount of frequency control is determined. At this time, the relationship between the phase difference correction amount for obtaining a desired phase difference (when the desired phase difference is 0, the phase difference correction amount is −Δtn) and the frequency control amount is expressed by the following equation ( 4) and the frequency control amount is determined so that the phase control time is the same as the synchronization period.

  Frequency control amount at T2 = phase difference correction amount / synchronization cycle−Δf (4)

  Here, in the first embodiment (see FIG. 5), the phase control time is shortened with respect to the phase monitoring time, but the operation clock frequency for controlling the operation clock frequency so as to obtain a desired phase difference is set. The amount of change increases. In order to minimize the amount of change, it is necessary to lengthen the phase control time, and accordingly, the synchronization period also becomes longer. Therefore, in the present embodiment (see FIG. 6), the next phase monitoring is performed at the same time as the phase control time with respect to the phase monitoring time in the previous time zone. As a result, the synchronization period can be shortened while the change amount of the operation clock frequency when controlling the operation clock frequency is minimized.

  As described above, in the present embodiment, the monitoring and phase control of the phase difference in the slave-side wireless device 4 are performed at the same time as the synchronization cycle. This makes it possible to minimize the amount of change in the operation clock frequency when controlling the operation clock frequency so as to achieve a desired phase difference without lengthening the synchronization period, and reducing the operation timing margin due to the frequency change. Deterioration can be prevented.

  Further, since the amount of change in the operating clock frequency is reduced, the frequency change width that the device generating the clock needs to cope with can be reduced, and the device cost can be reduced.

Embodiment 3 FIG.
In the second embodiment, as the phase synchronization operation in the slave-side wireless device 4, phase difference monitoring and phase control are performed at the same time as the synchronization cycle. In the present embodiment, phase control is completed in a time shorter than the synchronization period while monitoring the phase difference in the same time as the synchronization period. A different part from Embodiment 2 is demonstrated.

  FIG. 7 is a diagram illustrating the phase synchronization operation of the slave-side wireless device 4 in the present embodiment. In the slave-side wireless device 4, when the phase monitoring time and the synchronization period are set to the same value, and the phase control time is set to a value shorter than the synchronization period, the phase control is completed without waiting for the time of the synchronization period. It shows how the phase difference changes. In FIG. 7, the slave-side wireless device 4 calculates an average value for each reception timing of each packet by the synchronization timing extraction unit 41 for every fixed number, and the phase difference detection unit 45 from time T1 to time T2. The phase difference fluctuation amount is detected. At this time, in the phase control time from T1 to T4a in the time from time T1 to time T2, the clock frequency is set in a state where the frequency control calculated by the following equation (5) is performed at time T1. ing.

  Frequency control amount at T1 = phase difference correction amount at T1 / phase control time (T4a-T1) -frequency deviation at T1 (5)

  In the period from T4a to T2, the clock frequency is set in a state where the frequency control calculated by the following equation (6) is performed at time T4a.

  Frequency control amount at T4a = phase difference correction amount at −T1 / phase control time (T4a−T1) (6)

  Here, the frequency control at T4a is to remove the amount added to control the phase of the slave side wireless device 4 so that the phase difference with the master side wireless device 3 becomes a desired value. The frequency deviation detected at time T2 must be a value corresponding only to the state after the frequency control at T4a. At this time, if the frequency deviation is calculated using only the phase difference fluctuation amount from the time T4a to the time T2, the calculation error increases due to the shortened phase monitoring time, and the accuracy of the phase synchronization is deteriorated. is there. Therefore, the phase difference Δt2 at time T1 when the state after frequency control at T4a has continued from time T1 is calculated by the following equation (7), and the master side wireless communication is performed from time T1 to time T2. The phase difference fluctuation amount is detected on the assumption that the phase difference with the device 3 has changed from Δt2 to Δtn.

  Phase difference correction amount at Δt2 = Δt1 + T1 (7)

  The frequency deviation detector 46 monitors the phase difference information output from the phase difference detector 45 for each synchronization period, and the phase difference fluctuation amount (in the synchronization period corresponding to the time from time T1 to time T2) ( From Δtn−Δt2), the frequency deviation Δf at time T2 is calculated by the following equation (8).

  Frequency deviation (Δf) at T2 = phase difference fluctuation amount (Δtn−Δt2) / phase monitoring time (8)

  Next, the time (phase control time) until the clock frequency control unit 47 reaches a desired phase difference (for example, 0) with a predetermined fixed frequency control amount from the phase difference Δtn and the frequency deviation Δf at time T2. ) Is calculated and the operation clock frequency is controlled. At this time, the relationship between the phase difference correction amount for obtaining the desired phase difference (when the desired phase difference is 0, the phase difference correction amount is −Δtn) and the frequency control amount is expressed by the following equation: The phase control time can be calculated from this.

  Frequency control amount at T2 = phase difference correction amount at T2 / phase control time (T4b−T2) −Δf (9)

  Further, after the phase control time has elapsed since the frequency was controlled at time T2, the frequency control calculated by the following equation (10) is performed so that the frequency deviation becomes 0, as in the operation at time T4a. .

  Frequency control amount at T4b = phase difference correction amount at −T2 / phase control time (T4b−T2) (10)

  As described above, in the present embodiment, as the phase control in the slave-side radio apparatus 3, the operation clock frequency is controlled so as to achieve a desired phase difference with a fixed frequency control amount, and the phase difference becomes a desired value. After that, control was performed so that the frequency deviation became zero. As a result, a desired phase difference can be obtained without waiting for the time of the synchronization cycle, so that an increase in transmission time within the device due to the phase difference between devices can be suppressed, and a delay in packet transfer An increase in time can be prevented.

  Although the case where the phase control time is shorter than the phase monitoring time (synchronization cycle) has been described, when the phase difference at the time T2 is large, the desired phase difference is reached at the time T3 with a fixed frequency control amount. There are cases where it is not possible. In such a case, the difference from the desired phase difference may be carried over to the next phase control.

Embodiment 4 FIG.
Until the third embodiment, all wireless packets received by the slave-side wireless device 4 are targeted. In the present embodiment, retransmission packets are excluded from synchronization timing extraction targets. A different part from Embodiments 1-3 is demonstrated.

  FIG. 8 is a diagram illustrating a configuration example of the slave-side wireless device 4a in the present embodiment. The slave-side radio apparatus 4a includes a radio packet receiver 40a instead of the radio packet receiver 40, a synchronization timing extractor 41a instead of the synchronization timing extractor 41, and a retransmission packet detector 48. This is different from the first to third embodiments (see FIG. 3).

  The radio packet receiving unit 40a receives a packet transferred on the radio line 20, removes header information added to transfer on the radio line 20, outputs the packet to the apparatus, and outputs the header information. .

  The synchronization timing extraction unit 41a excludes the packet received by the wireless packet reception unit 40a from the synchronization timing extraction target according to the input exclusion instruction signal, and receives the packet as the synchronization timing extraction target. Memorize timing. Also, delay fluctuations in wireless transmission are detected for each of the stored reception timings, and the average value is calculated for each fixed number to average the delay fluctuations and store them as average reception timings. A common cycle is detected from the timing and output as a synchronization timing signal.

  The retransmission packet detector 48 detects that the packet received from the header information output from the wireless packet receiver 40a is a retransmission packet, and outputs an exclusion instruction signal to the synchronization timing extractor 41a. Here, the synchronization timing extraction unit 41a detects a common cycle from the average reception timing, for example, by any of the following methods. This is the same as the synchronization timing extraction unit 41 described above.

  1. The type of packet that is periodically transmitted is determined from the received packets, and only the reception timing is extracted.

  2. A period common to all packets is detected. For example, if all packets are transmitted according to the rule that if there is a packet to be transmitted at a certain time interval and not transmitted if there is no packet to be transmitted, the minimum value of the reception timing is set to all packets. A common cycle is used.

  As described above, in the present embodiment, the slave-side radio apparatus 4a detects retransmission of radio packets in the radio line 20, excludes them from the synchronization timing extraction target, and averages the delay fluctuations to determine the synchronization timing. It was decided to. Thereby, it is possible to suppress an error in phase synchronization caused by delay fluctuation due to retransmission of a wireless packet.

Embodiment 5 FIG.
In this embodiment, the reception timing is corrected by detecting the number of retransmissions of the wireless packet. A different part from Embodiment 1-4 is demonstrated.

  FIG. 9 is a diagram illustrating a configuration example of the slave-side wireless device 4b in the present embodiment. The slave-side radio apparatus 4b includes a radio packet receiver 40a instead of the radio packet receiver 40, a synchronization timing extractor 41b instead of the synchronization timing extractor 41, and a retransmission number detector 49. This is different from the first to third embodiments (see FIG. 3).

  The synchronization timing extraction unit 41b corrects the reception timing of the packet according to the increase in delay notified by the input correction instruction signal for the packet received by the wireless packet reception unit 40a, and stores this. Also, delay fluctuations in wireless transmission are detected for each of the stored reception timings, and the average value is calculated for each fixed number to average the delay fluctuations and store them as average reception timings. A common cycle is detected from the timing and output as a synchronization timing signal.

  The retransmission number detection unit 49 detects that the packet received from the header information output from the wireless packet reception unit 40a is a retransmission packet and the number of retransmissions, and determines the amount of increase in delay according to the number of retransmissions by using a correction instruction signal. Notify the synchronization timing extraction unit 41b. Here, the synchronization timing extraction unit 41b detects a common period from the average reception timing, for example, by any of the following methods. This is the same as the synchronization timing extraction unit 41 described above.

  1. The type of packet that is periodically transmitted is determined from the received packets, and only the reception timing is extracted.

  2. A period common to all packets is detected. For example, if all packets are transmitted according to the rule that if there is a packet to be transmitted at a certain time interval and not transmitted if there is no packet to be transmitted, the minimum value of the reception timing is set to all packets. A common cycle is used.

  As described above, in the present embodiment, the slave-side radio apparatus 4b detects the number of times the radio packet is retransmitted in the radio channel 20, corrects the reception timing, averages the delay fluctuations, and determines the synchronization timing. It was decided. Thereby, errors in phase synchronization due to delay fluctuations due to retransmission of radio packets can be suppressed, and a decrease in packets that can be used for synchronization timing extraction can be prevented.

  In each of the embodiments, the case where the master side wireless device 3 and the slave side wireless device 4 (4a, 4b) that are phase-synchronized via a wireless line are inserted between the master device 1 and the slave device 2 has been described. However, the present invention is not limited to such a configuration. For example, the present invention is also applicable to the case where the master device 1 and the master side wireless device 3 are integrated as the same device, and the slave device 2 and the slave side wireless device 4 (4a, 4b) are integrated as the same device.

  As described above, the phase synchronization apparatus according to the present invention is useful for a transmission system that performs packet communication, and is particularly suitable for synchronizing operations between apparatuses.

DESCRIPTION OF SYMBOLS 1 Master apparatus 2 Slave apparatus 3 Master side radio | wireless apparatus 4, 4a, 4b Slave side radio | wireless apparatus 10, 11 Wired line 20 Wireless line 30 Wired packet receiving part 31 Synchronization timing extraction part 32 Operation | movement clock generation part 33 Operation | movement timing generation part 34 Wireless Packet transmission unit 40, 40a Wireless packet reception unit 41, 41a, 41b Synchronization timing extraction unit 42 Operation clock generation unit 43 Operation timing generation unit 44 Wired packet transmission unit 45 Phase difference detection unit 46 Frequency deviation detection unit 47 Clock frequency control unit 48 Retransmission packet detector 49 Retransmission count detector

Claims (12)

A phase synchronization device that is inserted between a master device and a slave device sharing an operation cycle in a master-slave relationship, and establishes phase synchronization between the two devices via a wireless line;
In the case where the phase synchronization device includes a master-side wireless device that is phase-synchronized with the master device, and a slave-side wireless device that supplies synchronization timing to the slave device,
The master side wireless device is:
First synchronization timing extraction means for extracting a timing serving as a reference for phase synchronization from a packet received from the master device;
First operation timing generation means for determining a timing for transmitting a packet to the slave-side wireless device in synchronization with the reference timing;
First packet transmitting means for transmitting the received packet to the slave-side wireless device at the determined timing;
With
The slave side wireless device is:
Second synchronization timing extraction means for extracting a timing that is a reference for phase synchronization from a packet received from the master-side wireless device;
A phase difference detection means for detecting a phase difference by comparing the extracted timing with an operation timing in the device;
A frequency deviation detecting means for detecting a frequency deviation based on the phase difference;
Based on the phase difference and the frequency deviation, clock frequency control means for controlling the frequency of the operation clock in the device itself;
Second operation timing generation means for determining a timing for transmitting a packet to the slave device in synchronization with the reference timing;
Second packet transmitting means for transmitting the packet received at the determined timing to the slave device;
A phase synchronization apparatus comprising: In the slave side wireless device,
Monitoring of the operation phase between the master side radio apparatus and its own apparatus for detecting the frequency deviation in the frequency deviation detection means;
Control of phase difference by operation clock frequency control in the clock frequency control means;
The clock frequency control means determines the control amount of the operation clock frequency so that the phase difference becomes a desired value in the cycle based on the monitored result at different times in a fixed cycle. ,
The phase synchronization apparatus according to claim 1. In the slave side wireless device,
Monitoring of the operation phase between the master side radio apparatus and its own apparatus for detecting the frequency deviation in the frequency deviation detection means;
Control of phase difference by operation clock frequency control in the clock frequency control means;
The clock frequency control means determines the control amount of the operation clock frequency so that the phase difference becomes a desired value in the next period based on the monitored result at the same time period. ,
The phase synchronization apparatus according to claim 1. In the slave side wireless device,
Monitoring of the operation phase between the master side radio apparatus and its own apparatus for detecting the frequency deviation in the frequency deviation detection means;
Control of phase difference by operation clock frequency control in the clock frequency control means;
The clock frequency control means operates so that the phase difference becomes a desired value within a time shorter than the time period of the next period, based on the monitored result in the same time period with a fixed period. Determine the control amount of the clock frequency,
The phase synchronization apparatus according to claim 1. Furthermore, the slave side wireless device is
A retransmission packet detecting means for detecting retransmission of a wireless packet in a wireless line,
The synchronization timing extraction unit excludes the retransmitted radio packet detected by the retransmission packet detection unit from a target for extracting a timing serving as a phase synchronization reference.
The phase synchronization apparatus according to any one of claims 1 to 4, wherein Furthermore, the slave side wireless device is
A retransmission number detecting means for detecting the number of retransmissions of the wireless packet in the wireless line and outputting a correction instruction signal for correcting an increase in delay according to the number of retransmissions;
The synchronization timing extraction unit corrects the reception timing when extracting a timing serving as a phase synchronization reference using the retransmitted wireless packet based on the correction instruction signal.
The phase synchronization apparatus according to any one of claims 1 to 4, wherein A phase synchronization method in a phase synchronization device that is inserted between a master device and a slave device that share an operation cycle in a master-slave relationship and establishes phase synchronization between the two devices via a wireless line,
In the case where the phase synchronization device includes a master-side wireless device that is phase-synchronized with the master device, and a slave-side wireless device that supplies synchronization timing to the slave device,
A first synchronization timing extraction step in which the master-side wireless device extracts a timing that is a reference for phase synchronization from a packet received from the master device;
A first operation timing generation step for determining a timing at which the master-side wireless device transmits a packet to the slave-side wireless device in synchronization with the reference timing;
A first packet transmitting step in which the master-side wireless device transmits the received packet to the slave-side wireless device at the determined timing;
A second synchronization timing extraction step in which the slave-side wireless device extracts a timing that is a reference for phase synchronization from the packet received from the master-side wireless device;
The slave-side radio device detects the phase difference by comparing the extracted timing with the operation timing within the device,
The slave side radio device detects a frequency deviation based on the phase difference, a frequency deviation detection step;
A clock frequency control step in which the slave-side wireless device controls the frequency of an operation clock in its own device based on the phase difference and the frequency deviation;
A second operation timing generation step for determining a timing at which the slave wireless device transmits a packet to the slave device in synchronization with the reference timing;
A second packet transmission step in which the slave wireless device transmits the received packet to the slave device at the determined timing;
Including a phase synchronization method. Monitoring of the operation phase between the master-side radio device and its own device for detecting the frequency deviation in the frequency deviation detection step;
Control of phase difference by operation clock frequency control in the clock frequency control step;
Are performed at different times in a fixed period, and the control amount of the operation clock frequency is determined in the clock frequency control step so that the phase difference becomes a desired value in the period based on the monitored result. ,
The phase synchronization method according to claim 7. Monitoring of the operation phase between the master-side radio device and its own device for detecting the frequency deviation in the frequency deviation detection step;
Control of phase difference by operation clock frequency control in the clock frequency control step;
Are performed in the same time period with a fixed period, and the control amount of the operating clock frequency is determined in the clock frequency control step so that the phase difference becomes a desired value in the next period based on the monitored result. ,
The phase synchronization method according to claim 7. Monitoring of the operation phase between the master-side radio device and its own device for detecting the frequency deviation in the frequency deviation detection step;
Control of phase difference by operation clock frequency control in the clock frequency control step;
Are performed in the clock frequency control step so that the phase difference becomes a desired value within a time shorter than the time period of the next period based on the monitored result. Determine the control amount of the clock frequency,
The phase synchronization method according to claim 7. further,
The slave side wireless device includes a retransmission packet detection step of detecting retransmission of a wireless packet in a wireless line,
In the synchronization timing extraction step, the retransmitted radio packet detected in the retransmission packet detection step is excluded from targets for extracting a timing that is a reference for phase synchronization.
The phase synchronization method according to any one of claims 7 to 10, wherein: further,
The slave-side radio device detects the number of retransmissions of a radio packet in a radio line, and outputs a correction instruction signal for correcting a delay increase amount according to the number of retransmissions,
In the synchronization timing extraction step, based on the correction instruction signal, the reception timing is corrected when extracting a timing serving as a reference for phase synchronization using a retransmitted radio packet.
The phase synchronization method according to any one of claims 7 to 10, wherein:

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