JPH0714157B2 - Non-return clock selection type subscriber wireless system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to digital subscription in which a subscriber station installed on the user side of a digital transmission service and a base station forming one end of a digital transmission network are connected by a wireless line. The present invention relates to a subscriber wireless system, and more particularly, to a non-restoring clock selection type subscriber wireless system which is arranged in a remote area where a timing signal cannot be directly obtained from a digital clock distribution device forming a synchronous network and obtains a reference timing signal from a relay transmission signal. It is a thing.

[Conventional technology]

Conventionally, the digital subscriber radio system has been put into practical use as a high-speed digital leased line in order to realize a wide range of transmission services for digital terminals such as digital telephones, facsimiles, and computer data by connecting subscribers' homes with digital lines.

In this method, it is important that all devices, including the terminal device at the subscriber's house, which are interposed in the transmission path are processed in synchronization with one reference signal.

Therefore, the digital clock distribution device is input as a reference signal source to main devices of communication networks nationwide, and is synchronized with the digital clock distribution device, that is, performs signal processing of a synchronous network.

An example of a digital subscriber radio system which supplies a reference signal from a conventional digital clock distribution device is shown in FIG. 4 and explained.

FIG. 4 is a block diagram showing a conventional digital subscriber radio system in the case where a synchronizing signal is supplied from the digital clock distribution device. The signal processing device 40, the radio transmission / reception device 41 and the digital clock distribution device on the base station side. A device 45, a signal processing device 43 on the subscriber side, a radio transmitting / receiving device 42 and a terminal device 44 of the subscriber are included.

Then, the signals 4-1 to 4-n on the network side are input to the signal processing device 40 on the base station side, subjected to signal processing, and then transmitted to the opposite subscriber side via the wireless transmission / reception device 41. .

On the subscriber side, the signal is input to the signal processing device 43 on the subscriber side via the wireless transmission / reception device 42, subjected to signal processing, and then sent to the terminal device 44 of the subscriber.

On the contrary, the signals from the subscribers are output as the signals 4-1 to 4-n on the network side by the processing reverse to the above.

Further, since this processing is performed in synchronization with the network side, the reference signal 401, which is the network synchronization signal 400 distributed from the digital clock distribution device 45, is input.

As described above, since the digital clock is supplied by the digital clock distribution device where the main device of the transmission path is arranged, it is possible to provide an effective digital transmission service in such an area.

[Problems to be Solved by the Invention]

In the above-mentioned conventional digital subscriber radio system, in order to perform a remote area or a small-scale digital transmission service in which the digital clock distribution device is not installed, it is necessary to newly install the digital clock distribution device. There was an economic challenge of increasing capital investment.

[Means for Solving the Problems]

The non-revertive clock selection type subscriber radio system of the present invention is a digital subscriber radio system in which a subscriber station installed on the user side of a digital transmission service and a base station forming one end of a digital transmission network are connected by a radio line. In, means for extracting a clock signal of the digital transmission network from N (N: an integer of 1 or more) network side connection signals, and selection means for non-fixedly selecting one from the clock signals And a synchronizing signal generating circuit comprising a signal generating means synchronized with the signal selected by the selecting means and a judging means for outputting a signal for selection to the selecting means on the station side. It is what is done.

[Action]

In the present invention, the reference timing signal is obtained from the relay transmission signal by being installed in a remote area where the timing signal cannot be directly obtained from the digital clock distribution device forming the synchronous network.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention.

In the figure, 10 is a signal processing device on the base station side, 1-1 to 1
-N is a signal on the network side input to the signal processing device 10, 11
Is a radio transmitter / receiver on the base station side. Then, the signal processing apparatus 10 is configured to perform processing based on the timing signal synchronized with the clock signal extracted from the signals 1-1 to 1-n on the network side according to the present invention.

Reference numeral 12 is a subscriber-side wireless transmission / reception device, 13 is a subscriber-side signal processing device, and 14 is a subscriber's terminal device.

Then, the network side signals 1-1 to 1-N are input to the signal processing device 10 on the base station side, subjected to signal processing, and then transmitted to the opposite subscriber side via the wireless transmission / reception device 11.

On the subscriber side, the signal is input to the signal processing device 13 on the subscriber side via the wireless transmission / reception device 12, subjected to signal processing, and then sent to the terminal device 14 of the subscriber.

On the contrary, the signals from the subscribers are outputted as the signals 1-1 to 1-N on the network side by the processing reverse to the above.

FIG. 2 is a block diagram showing an embodiment of a synchronizing signal generating circuit which is a main part of the non-restoring clock selection type subscriber radio system according to the present invention.

In the figure, 100 is a synchronizing signal generating circuit, and this synchronizing signal generating circuit 100 is a signal processing device 10 on the base station side shown in FIG.
Is equipped with.

20-1, 20-2 ... 20-N is a clock extraction unit, and these clock extraction units 10-1 to 20-N are N (N: an integer of 1 or more)
Means for extracting the clock signal of the digital transmission network from the connection signal on the network side. 21 is this clock extraction unit
A switching unit for switching the outputs of 20-1 to 20-N, and this switching unit 21 constitutes a selecting means for non-fixedly selecting one of the clock signals. 22 is a synchronizing signal generator,
The synchronization signal generator 22 constitutes a signal generator that synchronizes with the signal selected by the selector. Reference numeral 23 denotes a switching control unit, and the switching control unit 23 constitutes a determination unit that outputs a selection signal to the selection unit. 24 is a signal processing unit.

2-1, 2-2 ... 2-N indicates a signal on the network side, and 2
00-1,200-2 ... 200-N is the network side clock signal, 201
Is a reference clock signal, 202 is a switching control signal, 203-1 to 20
3-N is a switching signal, and 204 is a reference signal.

Next, the operation of the embodiment shown in FIG. 2 will be described with reference to FIG.

First, the signal processing device 10 on the base station side shown in FIG. Then, the signal 2 on the network side
1 to 2-N are converted in the signal processing device 10 on the base station side shown in FIG. As the transmission path code, a code from which a clock component can be easily extracted is selected from the signal sequence to be transmitted.

A clock extraction unit 20-1, 20 for extracting a clock component from the signals 2-1 to 2-N on the network side having the above characteristics.
-2: Clock signal on the network side extracted by 20-N
200-1, 200-2 ... 200-N is input to the switching unit 21.

The switching unit 21 uses the switching control signal 202 from the switching control unit 23 to extract the extracted clock signals 200-1 to 200-N on the network side.
One of the N clocks is selected and sent as the reference clock signal 201 to the synchronizing signal generator 22.

Next, the synchronization signal generator 22 is conventionally configured of a phase-locked oscillator (PLO) for the purpose of generating a reference clock in the device, and the clock extractors 20-1 to 20-N are
Absorbs components such as jitter generated between transmission lines that could not be suppressed, creates the reference signal 204 of the subscriber wireless device, and sends to the signal processing unit 24 all necessary for signal transmission and reception between the subscriber wireless devices. Signal processing is performed. Then, the switching control unit 23 may eliminate the network-side clock signals 200-1 to 200-N extracted by the clock extraction units 20-1 to 20-N due to a failure of the network or the transmission device. , When the network becomes asynchronous, a switching signal 203 made from an asynchronous alarm and a loss alarm of each network corresponding to the signals 2-1 to 2 to N on the network side.
The switching control signal 202 for switching to another normal clock signal is output to the switching unit 21 by -1 to 203-N.
This switching control unit 23 represents the feature of the present invention, and will be described in more detail.

The switching control signal 202 is not always configured to preferentially select a particular network. That is, even if all networks are normal, for example, the signal 2-1 on the network side is not always preferentially selected. Only when there is an abnormality, another signal is selected. (At this time, the selection may be performed in order.) Further, even when the signal selected until immediately before the switching is restored to normal, the selection is kept and is not switched back.

Generally, when the reference clock of the entire system is input from the outside, it is usual to take a dual structure of working / spare. Moreover, the spare is used only temporarily, and is returned to the working state immediately when the working state is restored to normal.

However, in this case, in order to freely switch between the working / spare,
In order to prevent jumps and fluctuations in the reference clock of the system during switching, it is necessary to perform operations such as controlling the phases of the input clock from the outside and the reference clock with each other, which usually results in a complicated configuration. However, when a small-scale digital transmission service is provided, it is difficult to realize economically.

According to the configuration of the present invention, even if the above-described configuration is not adopted, the influence on the clock due to the switching back can be avoided, and the effective reference clock can be selected.

As a simple example, when there are two input clocks and one of them is selected, a simple example in which the present invention is implemented will be described with reference to FIG. 3. The clock signals 300-1, 300-2 on the network side will be described.
Is input to the IC switch 30. Further, the switching signals 302-1 and 302-2 generated from the asynchronous alarm and the loss alarm of the network are input to the switching control unit 31. The switching control unit 31 is configured by a NAND gate, and is configured so that when the switching control signal 303 is at the "H" level, the network side clock signal 300-1 side is selected and output as the reference clock signal 301. . Then, the clock signals 300-1, 300-2 on the network side
Is normal, the switching control signal 303 is not uniquely determined to be “H” or “L”. If the clock signal 300-1 on the network side is selected by "L", the clock signal 300-2 on the network side is selected by "H". That is, the clock signal 300-1 on the network side fails. Only when the switching signal 302-1 becomes "L" at. Further, even if the clock signal 300-1 on the network side is restored to normal, the switching control signal 303 is
It is controlled so as to select the clock signal 300-2 on the network side while keeping "H".

〔The invention's effect〕

As described above, the present invention is installed in a remote area where a timing signal cannot be directly obtained from a digital clock distribution device that constitutes a circuit network, and a reference timing signal is obtained from a relay transmission signal, so that the digital clock distribution device can be obtained. No need to install a new digital clock distribution device for small-scale digital transmission services where no network is installed, and a complicated reference clock selection circuit is required when extracting a network clock from the transmission line. In other words, there is an effect that an economical digital transmission system configuration can be achieved.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of a non-revertive clock selection type subscriber wireless system according to the present invention, and FIG. 3 is a simple diagram in which the present invention is implemented. FIG. 4 is a block diagram showing an example of a conventional digital subscriber radio system. 10 ... Signal processor, 11,12 ... Wireless transceiver, 13 ...
... Signal processing device, 14 ... Terminal device, 20-1 to 20-N ...
Clock extraction unit, 21 ... switching unit, 22 ... synchronization signal generation unit, 23 ... switching control unit, 24 ... signal processing unit, 30 ... IC switching unit, 31 ... switching control unit.

Claims (1)

[Claims] 1. A digital subscriber radio system in which a subscriber station installed on the user side of a digital transmission service and a base station forming one end of a digital transmission network are connected by a radio line,
Means for extracting a clock signal of the digital transmission network from N (N: an integer greater than or equal to 1) network side connection signals; and selecting means for non-fixedly selecting one of the clock signals. The base station side is provided with a synchronizing signal generating circuit including a signal generating means synchronized with the signal selected by the selecting means, and a judging means for outputting a signal for selection to the selecting means. Non-revertive clock selection type subscriber wireless system characterized by the following.