JP3069820B2 - Clock slave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a time-division multiplexing device of a digital synchronous transmission system, extracts clocks from a plurality of digital transmission lines, selects an arbitrary clock, and uses the clock to control the device. The present invention relates to a clock slave device that slave-synchronizes a synchronization reference clock.

[0002]

2. Description of the Related Art As shown in FIG. 3, a clock dependent device used in a conventional time-division multiplexing device has n clock extracting units 22-1 to 22-n in a unit rack 21.
, A reference clock control unit 23, and a common processing unit 24.

[0003] The n clock extraction units 22-1 and 22-2
2-n denotes n corresponding digital transmission paths 25-
A multiplexed digital signal is input from 1 to 25-n, and a reference clock signal is extracted from the digital signal. The reference clock signals extracted by the units 22-1 to 22-n are sent to the common processing unit 24 via the reference clock lines 26-1 to 26-n wired to the unit rack 21, respectively.

[0004] The reference clock control unit 23 is connected to any one of the alarm lines 27-1 to 27-n (arbitrarily selectable) which are wired corresponding to the n reference clock lines 26-1 to 26-n. Transmit the alarm signal.

The common processing unit 24 includes reference clock lines 25-1 to 25-n and alarm lines 27-1 to 27-n.
n is the alarm detection circuit 241-1 to 241-n, respectively.
To the slave switching circuit 242.

Then, the input reference clock is supplied from a slave switching circuit 242 to a PLL (phase locked loop) circuit 243 as a slave clock, and the synchronization reference clock generated by the PLL circuit 243 is phase-synchronized with the slave clock. Then, the frequency is divided at a predetermined ratio by a frequency dividing circuit 244, whereby the reference clock for synchronization of the device is subordinately synchronized with an arbitrary reference clock.

[0007] However, in the above-described conventional clock-dependent device, the clock line is previously wired to each unit rack in order to transmit the reference clock extracted by each clock extraction unit to the common processing unit. Therefore, the number of clock lines that can be physically wired in one rack is limited.

[0008] In addition, the switching order of the slaves is fixed in such a manner that a reference clock line is fixedly wired to the common processing unit for each clock extraction unit, and the priority is fixedly fixed by the reference clock control unit, the reference clock alarm detection circuit and the slave switching circuit. Since it has been determined, when the switching order is switched, for example, in priority order, (mounting position) = (priority order) is fixed.

Further, even if a new clock extraction unit is connected due to the addition of a system or the like, depending on the mounting position of the clock extraction unit, dependent synchronization cannot be performed,
Priority may be low.

[0010]

As described above, in the conventional clock dependent device, the number of reference clock lines wired in one unit rack is physically limited.
In addition, since the wiring is fixed to the priority dependent switching circuit of the common processing unit, depending on the mounting position of the clock extraction unit, dependent synchronization cannot be performed, or the priority of the switching order is low, and so on in network construction.
There was a drawback that it could not respond flexibly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a time-division multiplexing apparatus of a digital transmission system, when a synchronization reference clock is dependently synchronized with a reference clock of an arbitrary digital signal, a reference signal is used. It is an object of the present invention to provide a clock slave device that can execute slave synchronization regardless of where a clock extraction unit is mounted in a unit rack, and that can flexibly cope with a change in slave destination.

[0012]

In order to achieve the above object, a clock slave device according to the present invention is used for a time-division multiplexing device of a digital synchronous transmission system, and is provided on a unit rack from a plurality of digital transmission lines. Each of the clock slaves extracts a clock, selects an arbitrary clock, and slave-synchronizes the synchronization reference clock of the device with the clock. A plurality of clock extraction units having a function of inputting a signal and extracting a reference clock signal from the digital signal and a function of generating an alarm signal according to designation by a control signal, and a plurality of clock extraction units wired to a unit rack and transmitted from the plurality of clock extraction units A reference clock line for transmitting the reference clock And an alarm information line that is transmitted as alarm information according to the mounting position of the unit, and becomes multiplexed information indicating presence / absence of an alarm signal of each unit by sending an alarm signal from a plurality of clock extraction units. A reference clock transmission control line wired to the rack and transmitting a control signal indicating transmission permission to a plurality of clock extraction units, and a plurality of clocks mounted on the unit rack through a reference clock line, an alarm information line, and a reference clock transmission control line. A common processing unit connected to the extracting unit, the common processing unit receiving alarm information from the alarm information line to identify mounting positions of the plurality of clock extracting units, and identifying the identifying means. The decision to determine any clock extraction unit as a dependent based on the result Means for transmitting a control signal indicating transmission permission to the clock extraction unit determined by the determination means through a clock transmission control line, and a synchronization reference of the apparatus based on a reference clock transmitted through the reference clock transmission control line. Means for subordinately synchronizing the clock.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In order to achieve the above object, a clock slave device according to the present invention is used for a time-division multiplexing device of a digital synchronous transmission system, and extracts clocks from a plurality of digital transmission lines on a unit rack, respectively. In a clock slave device that selects an arbitrary clock and slave-synchronizes the synchronization reference clock of the device with the clock, the multiplexed digital signal is input from a plurality of corresponding digital transmission paths, each being mounted on the unit rack, A clock extraction unit having a function of extracting a reference clock signal from the digital signal and a function of generating an alarm signal according to designation by a control signal; and a reference clock wired to the unit rack and transmitted from the plurality of clock extraction units. The reference clock line to be transmitted and the unit rack The alarm signal is transmitted from the plurality of clock extraction units, and the multiplexed information indicates the presence / absence of an alarm signal of each unit. The alarm information line transmits as alarm information according to the mounting position of the unit. A reference clock transmission control line wired to a rack and transmitting a control signal indicating transmission permission to the plurality of clock extraction units; and a reference clock transmission line, an alarm information line, and a reference clock transmission control line mounted on the unit rack. A common processing unit connected to the plurality of clock extraction units, wherein the common processing unit converts a subordinate order to a mounting position of the plurality of clock extraction units into a preset order, Conversion information is controlled as information for switching dependents within the common processing unit And a control unit that, the received alarm information from the alarm information lines to determine the mounting position of the plurality of clock extraction unit, said control
Means to sort in the order of dependent units preset by means
And beauty replacement means selects the clock extraction unit which is the next antecedent based on the rearrangement result of the rearranging unit,
Determining means for determining, and transmitting means for converting the mounting position of the clock extracting unit determined by the determining means based on information from the control means, and transmitting a control signal indicating transmission permission through the clock transmission control line And means for subordinately synchronizing the synchronization reference clock of the device with the reference clock transmitted through the reference clock transmission control line.

Each of the clock extraction units 12-1 to 12-
n is n corresponding digital transmission paths 14-1 to 14-1 respectively.
14-n, a multiplexed digital signal is input, and a reference clock signal is extracted from the digital signal. Further, it has a function of generating an alarm signal according to designation by a control signal.

Each of the clock extraction units 12-1 to 12-
n and the common processing unit 13 are connected by a reference clock line 151, an alarm information line 152, and a reference clock transmission control line 153 that are wired in advance in the unit rack 11. The clock extraction units 12-1 to 12-n send an alarm signal to the alarm information line 152 and send a reference clock to the reference clock line 151 only when receiving the sending permission signal from the reference clock sending control line 153. . FIG. 2 shows an example of each transmission signal of the alarm information line 152 and the reference clock transmission control line 153.

On the other hand, the common processing unit 13 uses the mounting position information / dependent destination unit order conversion circuit 131, the dependent destination selection switching circuit 132, the dependent destination unit order / mounted position information conversion circuit 133, and the conversion control circuit 134 to determine the dependent destination. decide. 1e is dependent unit order information, 1f is dependent unit order alarm information, and 1g is dependent unit designation information.

Further, the common processing unit 13 supplies the reference clock from the reference clock line 151 to the PLL circuit 135 as a dependent clock, and controls the synchronization reference clock generated by the PLL circuit 135 with the dependent clock. The frequency is further divided at a predetermined ratio by a frequency dividing circuit 136.
Thereby, the synchronization reference clock of the device is subordinately synchronized with an arbitrary reference clock.

Next, a description will be given of the switching operation of the dependent party.

Each of the clock extraction units 12-1 to 12-
n from the alarm information line 152
, Is multiplexed according to the mounting position, and becomes alarm information indicating the position of the dependent unit. Upon receiving the alarm information, the mounting position information / dependent unit forward conversion circuit 131 determines the position of the unit currently designated as the dependent unit from the alarm signal, and converts the unit to the conversion control circuit 134.
From the order of the subordinate unit specified in advance.

The slave selection switching circuit 132 selects the next clock extraction unit to be slaved according to the slave unit order alarm information 1f from the conversion circuit 131. The dependent unit designation information 1g of the selected unit is sent to the dependent unit order / mounting position information conversion circuit 133.

The slave unit order / mounting position information conversion circuit 133 rearranges the slave unit order in the mounting position according to the slave unit order information 1e from the conversion control circuit 134 and sends the rearranged unit order to the reference clock sending control line 153. I do. The clock extraction units 12-1 to 12-n are switched to the next dependents according to the content of the control signal.

That is, in the clock slave device having the above-mentioned configuration, the reference clock line is shared by one, and the function of generating a clock extraction alarm signal is performed by each clock extraction unit 12-.
1 to 12-n, and the clock extraction unit 12-
An alarm signal output from each of the clock extraction units 12-1 to 12-n is output for each mounting position of the clock extraction units 12-1 to 12-n. Put it in a book. This alarm information is rearranged in the common processing unit 13 in the order of the subordinate destination unit in which the information is specified, and a clock extraction unit which subordinates next is determined based on the information, and a reference clock transmission permission to the unit is output to the mounting position. . Only the clock extraction unit that has received the reference clock transmission permission outputs the reference clock to the reference clock line, thereby performing slave synchronization.

Therefore, according to the clock slave device having the above-described configuration, slave synchronization using the extracted reference clock can be realized regardless of the mounting position of the clock extraction unit regardless of the mounting position. The previous switching order can be freely changed. Therefore, it is possible to flexibly cope with the construction of a network without limiting the number of subordinates.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0026]

As described above, according to the present invention, when a synchronization reference clock is dependently synchronized with a reference clock of an arbitrary digital signal in a time division multiplexing device of a digital transmission system, a clock extraction unit is provided. It is possible to provide a clock dependent device that can execute dependent synchronization regardless of where it is mounted in a unit rack, and that can flexibly respond to changes in the dependent destination.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a clock slave device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of each transmission signal of an alarm information line and a reference clock transmission control line of the embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional clock dependent device.

[Explanation of symbols]

 11 Unit Rack 12-1 to 12-n Clock Extraction Unit 13 Common Processing Unit 131 Mounting Position Information / Dependent Unit Forward Conversion Circuit 132 Dependent Destination Selection Switching Circuit 133 Dependent Destination Unit Order / Mounting Position Information Conversion Circuit 134 Conversion Control Circuit 135 PLL circuit 136 Frequency divider circuit 14-1 to 14-n Digital transmission path 151 Reference clock line 152 Alarm information line 153 Reference clock transmission control line 1e Dependent unit order information 1f Dependent unit order alarm information 1g Dependent unit designation information 21 Unit rack 22-1 to 22-n Clock extraction unit 23 Reference clock control unit 24 Common processing unit 241-1 to 241-n Alarm detection circuit 242 Dependent switching circuit 243 PLL circuit 244 Divider circuit 25-1 to 25-n Digital Transmission line 26-1 to 26-n Reference clock line 27-1 to 27-n Alarm line

Claims (1)

(57) [Claims] The present invention is used for a time-division multiplexing device of a digital synchronous transmission system, and extracts clocks from a plurality of digital transmission lines on a unit rack, selects an arbitrary clock, and synchronizes the device with the clock. A clock dependent device for dependently synchronizing the reference clock for use, a function and a control signal mounted on the unit rack, each of which receives a multiplexed digital signal from a plurality of corresponding digital transmission paths and extracts a reference clock signal from the digital signal. A clock extraction unit having a function of generating an alarm signal in accordance with the designation by; a reference clock line wired to the unit rack and transmitting a reference clock sent from the plurality of clock extraction units; and a reference clock line wired to the unit rack; An alarm signal is output from the plurality of clock extraction units. The multiplexed information indicates the presence / absence of an alarm signal of each unit, and is transmitted to the plurality of clock extraction units by being multiplexed to indicate the presence or absence of an alarm signal of each unit and transmitted as alarm information according to the mounting position of the unit. A reference clock transmission control line for transmitting a control signal indicating permission, and the reference clock line mounted on the unit rack,
A common processing unit connected to the plurality of clock extraction units through an alarm information line and a reference clock transmission control line, wherein the common processing unit presets a dependency order with respect to a mounting position of the plurality of clock extraction units. Control means for converting the converted information to a predetermined order, and controlling the converted information as information for switching the subordinates in a common processing unit; and receiving the alarm information from the alarm information line and implementing the plurality of clock extracting units. Determine the position and
Rearrange in the order of dependent units set in advance by control means
Wherein the rearranging means, based on the rearrangement result of the rearranging unit selects the clock extraction unit which is the next antecedent, a determination unit determining, the mounting position of the clock extracting unit determined by the determining means A transmitting means for converting a control signal indicating transmission permission through the clock transmission control line based on information from the control means, and a synchronization reference of the apparatus based on a reference clock transmitted through the reference clock transmission control line. And means for subordinately synchronizing the clock.