JPH0229043A - Phase calibration system - Google Patents

Abstract

PURPOSE:To calibrate the phase of a slave equipment accurately from a master equipment arranged apart geographically by allowing the slave equipment to reproduce a reference phase from a reference frequency signal received from the master equipment and to calibrate it based on the phase information. CONSTITUTION:The master equipment 1 is provided with a phase comparator 14 comparing the phase of its own reference frequency signal outputted from a reference frequency generating section 11 with the phase of a signal received from a return transmission line 4 by a return signal reception section 13 and a phase information transmission section 15 sending the phase information outputted from the phase comparator 14 to the slave equipment 2 via a phase transmission line 5 outputted from the phase comparator 14. The slave equipment 2 is provided with a phase ratio control section 25 calibrating the phase outputted from a reference phase reproducing section 22 according to the phase information. Thus, the phase of the equipment arranged at a location apart geographically is calculated by the accuracy of the reference frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applied to a time-synchronized communication network. In particular, it relates to a phase calibration scheme for calibrating the phase of geographically separated devices.

The present invention is suitable for use in, for example, synchronization between earth stations in satellite relay TDMA and time services in communication networks.

[Conventional technology]

2. Description of the Related Art In order to synchronize two devices located geographically apart, a method has conventionally been used in which one device generates a reference phase signal and transmits this signal to the other device. In this specification, a device that generates a reference phase is referred to as a main device,
A device that receives and reproduces the reference phase is called a slave device. To transmit the reference phase signal, in order to compensate for the transmission delay of the reference phase signal, it is necessary to determine the amount of transmission delay and advance the phase of the reference phase signal accordingly. The conventional methods for determining transmission delay ■ are: (1) method of determining from the transmission speed of the reference phase signal; (2) method of determining from the transmission speed of the reference phase signal;
A method is used in which the amount of transmission delay is actually measured using a round-trip transmission path.

In method (1), when the transmission speed of the reference phase signal in the transmission line set between the main device and the slave device is V and the transmission distance is β, the transmission delay amount τ is τ= jl! /
It is determined by v ・−(1). However, this method requires accurate measurement of the transmission distance β.

In addition, as the simplest method of method (2), by sending back the reference phase signal with the slave device that regenerates (requests) the reference phase, the total transmission delay of the outgoing transmission path and the incoming transmission path can be determined on the main device side. T is measured, and the transmission delay amount of the outgoing transmission line is τ= T / 2 −−−− (2
) is known.

[Problem that the invention seeks to solve]

However, in order to accurately correct the transmission path delay amount, (1
) method requires accurate measurement of transmission distance l,
There were disadvantages that could not be measured due to geographical or environmental conditions. In addition, with method [2], it is necessary to measure the amount of transmission delay on the main device side for each slave device, and when there are many slave devices, the load on the main device increases and phase control becomes complicated. there were. Another drawback is that it is complicated to change the main device when adding a new slave device.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a phase calibration method that can accurately calibrate the phase of a slave device from a main device located geographically apart from the slave device.

[Means for solving problems]

The phase calibration method of the present invention includes a main device and a slave device that are connected to each other via an outbound transmission line and a return transmission path, and the main device includes a reference frequency generator that generates a reference frequency signal, and a reference frequency generator that generates a reference frequency signal. The slave device includes a reference frequency transmitting section that sends the signal to the slave device via the outgoing transmission path, and the slave device includes a reference phase reproducing section that regenerates the reference phase from the signal received from the outgoing transmission path, and a reference frequency transmitting section that transmits the signal to the slave device via the outgoing transmission path. The main device further includes a phase comparator that compares the phase of its own reference frequency signal with the signal received from the return transmission path, and a reference signal return unit that sends the reference signal back to the main device via the and means for transmitting the output phase information to the slave device, and the slave device further includes a phase control unit that calibrates the phase output by the reference phase reproducing unit according to the phase information.

[For production]

A reference frequency signal is transmitted from the master device to the slave device, and this signal is sent back from the slave device to the master device. At this time, the main device determines the phase difference between the transmitted signal and the returned signal, and sends this as phase information to the slave device. This phase information represents the amount of delay variation caused by the two transmission paths, the outgoing transmission path and the inbound transmission path.

Therefore, the slave device reproduces the reference phase from the reference frequency signal received from the main device and calibrates this based on the phase information.

〔Example〕

The figure is a block diagram showing a phase synchronization method according to an embodiment of the present invention.

This embodiment includes a main device 1 and a slave device 2 that are connected to each other via an outbound transmission line 3 and a return transmission line 4.

The main device 1 includes a reference frequency generator 11 that generates a reference frequency signal, and a reference frequency transmitter 12 that sends this reference frequency signal to the slave device 2 via the outgoing transmission line 3.

The slave device 2 includes a reference frequency receiving section 21 that receives a reference frequency from the outgoing transmission line 3 and reproduces the reference frequency, a reference phase reproducing section 22 that reproduces a reference phase from the output of the reference frequency receiving section 21, and a reference frequency receiving section 22 that reproduces the reference phase from the output of the reference frequency receiving section 21. a reference signal return section 2 that returns the output of the reception section 21 to the main device 1 via the return transmission line 4;
3.

The main device 1 further includes a phase comparator 1 that compares the phase of its own reference frequency signal output from the reference frequency generator 11 and the signal received from the return transmission path 4 by the return signal receiver 13.
4, and a phase information transmitter 15 that transmits the phase information output from the phase comparator 14 to the slave device 2 via the phase transmission line 5.
Equipped with. The slave device 2 further includes a phase control section 25 that calibrates the phase output by the reference phase reproducing section 22 according to this phase information.

The phase calibration accuracy in this embodiment depends on the accuracy with which the phase comparator 14 on the main device 1 side detects the reference frequency fluctuation reaching the reference frequency receiving section 21. Here, the phase variation T detected by the phase comparator 14 is T,=ΔT,+Tc+
It is expressed as ΔT1. Here, ΔT0: Delay variation in the outbound transmission line 3 To: Phase variation in the reference frequency receiving section 21 ΔTi: Delay variation in the inbound transmission line 4.

In the above equation, if the amount of phase fluctuation in the reference frequency receiving section is negligible, ΔT0 = ΔTl by using the same transmission path for the outward and return routes. Therefore, the phase comparator 14 observes a value twice the fluctuation of the reference frequency. The phase control unit 25 controls the reference phase reproducing unit 22 so that the phase changes by half of this value.

In the above embodiments, the forward transmission line, return transmission line, and phase transmission line are shown as separate transmission lines, but the present invention can be implemented in the same way even if the same transmission line is used.

Furthermore, in the above embodiment, the case where the phase of one slave device is calibrated from one main device is explained as an example, but in practical terms, it is possible to calibrate the phase of multiple slave devices from one main device. can. In this case, the main device transmits the same reference frequency to each slave device, and transmits phase information to each slave device according to the return signal from each slave device. As a result, even if the number of slave devices increases, the main device only detects the phase difference and transmits the information, and there is no need to control the phase of each slave device.

〔Effect of the invention〕

As described above, the phase calibration method of the present invention can calibrate the phase of devices located at geographically distant locations with reference frequency accuracy.

When the present invention is applied to a satellite relay TDMA earth station, a plurality of earth stations can be connected through a transmission path different from a signal line and synchronized with each other. This has the effect that synchronization can be set separately from burst synchronization and synchronization can be quickly set when receiving a burst signal.

In addition, by using a time-synchronized communication network to synchronize each device within the network, accurate time services can be provided, and when a failure occurs, the location of the failure can be easily detected based on the time of occurrence, making maintenance and management possible. This has the effect of making it easier.

[Brief explanation of the drawing]

The figure is a block diagram showing a phase calibration method according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Main device, 2... Slave device, 3... Outbound transmission line, 4... Return transmission line, 5... Phase transmission line, 11...
・Reference frequency generation section, 12...Reference frequency transmission section, 1
3... Return signal receiving section, 14... Phase comparator, 15
... phase information transmitting section, 21... reference frequency receiving section,
22... Reference phase reproducing section, 23... Reference signal returning section, 24... Phase information receiving section, 25... Phase controlling section. Agent Patent Attorney Naotaka Ide

Claims (1)

[Claims] 1. A main device and a slave device are connected to each other via an outbound transmission line and a return transmission path, and the main device includes a reference frequency generator that generates a reference frequency signal, and a reference frequency generator that generates a reference frequency signal. a reference frequency transmission section that sends a signal to the slave device via the outbound transmission path, and the slave device includes a reference phase regeneration section that reproduces a reference phase from the signal received from the outbound transmission path; a reference signal return unit that returns the reference frequency signal to the main device via the return transmission path, and the main device further includes a phase comparison unit that compares the phase of its own reference frequency signal and the signal received from the return transmission path. and means for transmitting phase information output from the phase comparator to the slave device, and the slave device further includes a phase control unit that calibrates the phase output by the reference phase regeneration unit according to the phase information. Phase calibration method including.