JPS60248040A - Digital subscriber line burst transmission and reception system - Google Patents

Abstract

PURPOSE:To stop the transmission of an ineffective burst signal by allowing a digital circuit terminator at calling to decide the transmission period of a subscriber burst and a station and a digital subscriber circuit at incoming to decide it independently respectively. CONSTITUTION:A synchronizing mode switching signal MX is set to an independen synchronizing mode at calling of a subscriber's equipment and a transmission start signal is transmitted to a burst timing circuit BT of a digital line terminator DSU, then the circuit BT decides independently the transmission period of a subscriber burst signal Bs at each burst period independently and transmits it to a transmission circuit SD and a switch circuit SW. The circuit SD transmits the signal Bs to a digital subscriber circuit DLC via subscriber line SL. When a station burst signal Bo from the circuit DLC is received by the terminator DSU at incoming, a frame synchronizing circuit FS detects the arrival period of the signal Bo and transmits the signal to the circuit BT. Thus, the circuit BT decides the transmission period of the signal Bs and transmits the signal to the circuit DLC via the circuit SD. The circuit DLC decides the transmission period of the signal Bo independently at incoming and depending on the signal Bs at calling.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a two-wire time-division transmission system subscriber line, and more particularly to a digital subscriber line burst transmission/reception system that can invalidate the transmission of burst signals. In recent years, with the advancement of digital switching technology, attempts have been made to digitize subscriber line transmission systems. FIG. 1 is a diagram showing an example of a subscriber transmission system to which the present invention is applied, and FIG. 2 is a diagram showing an example of the subscriber line transmission system in FIG. In FIG. 1, a terminal device DT installed in a subscriber's premises
It is connected to the digital subscriber circuit DLC provided in the exchange 131EX via a device SL consisting of a digital line termination device DSU and a digital line termination device DSU. In FIG. 2, the digital subscriber circuit DLC is connected to the network N
A frame signal F and a DC Harans bit B are added to the data signal D and control signal S transmitted from W to generate a station hearth Bo, and a predetermined period (hereinafter referred to as the Hurst period Tb
The digital line terminating device DSU also adds a frame signal F and a DC balance bit B to the data signal and control signal S transmitted from the terminal device DTE to generate a subscriber burst. Bs is generated and sent to the subscriber line SL every burst period Tb. In order to make it possible for the station burst Bo and the subscriber burst BS to be transmitted via the two-wire subscriber line SL without colliding with each other, the transmission timing of the station burst Bo in the digital subscriber circuit DLC, It is necessary to perform so-called burst synchronization, which adjusts the transmission timing of the subscriber burst Bs in the digital line termination unit DSU. [Prior Art] In a conventional digital subscriber line burst transmission/reception system, the home equipment SE was dependent on the exchange EX for burst synchronization. That is, the digital subscriber circuit DLC independently determines the sending timing of the station burst Bo, and the digital line termination unit DSU extracts the frame signal F from the station burst BO transmitted via the subscriber line SL. The arrival time of the burst Bo is detected, and the time to send the subscriber burst t-Bs from the own device is determined based on the arrival time. [Problems to be Solved by the Invention] As is clear from the above explanation, in the conventional digital subscriber line burst transmission/reception system, the home equipment was dependent on the digital subscriber circuit to achieve burst synchronization. Therefore, if the subscriber is absent, it is possible to turn off the power to the in-home equipment and stop sending subscriber bursts, but if the digital subscriber circuit is not constantly sending out station bursts, Since the timing of transmitting subscriber bursts cannot be determined when the equipment is powered on, the digital subscriber circuit wastes power by transmitting station bursts even when the in-home equipment is not functioning. This also has the disadvantage of increasing the noise level imparted to adjacent subscriber lines due to crosstalk. [Means for solving the problem] The problem is that the digital subscriber circuit and the home equipment, which are connected by a two-wire subscriber line, send out burst signals to each other in a time-division manner at a predetermined period. In the time-division transmission system subscriber line, the in-home device has means for independently determining when to send out a burst signal from the own device when a call is made, and means for detecting the burst signal transmitted from the digital subscriber circuit when a call is received. means for determining the burst signal sending timing of the own device based on the arrival time of the burst signal; This can be solved by providing means for detecting a burst signal transmitted from the home device during a call and determining the burst signal sending timing of the own device based on the arrival time of the burst signal. [Operation] That is, in the present invention, when a call is made, the digital subscriber circuit is subordinated to the in-home equipment and performs burst synchronization,
When a call arrives, the home equipment follows the digital subscriber circuit and performs burst synchronization. Therefore, in a no-call state, neither the digital subscriber circuit nor the customer premises equipment needs to send out bursts, which consumes reactive power and increases the noise level on adjacent subscriber lines due to crosstalk. Prevented. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a digital subscriber line burst transmission/reception system according to an embodiment of the present invention, and FIG. 4 is a diagram showing an example of the subscriber line transmission system at the time of calling on the first page. Note that the same reference numerals indicate the same objects throughout the figures. 1st
In the figure, the digital line termination bag fiDsU includes a receiver RV that receives the station burst BO arriving from the subscriber line SL, and a clock signal on the exchange EX side from the station burst BO received by the receiver RV. A bit synchronization circuit BS that synchronizes clock signals in the device DSU, and a frame synchronization circuit that detects a frame signal F from the station burst Bo, separates a data signal and a control signal S, and transmits them to a terminal device DTE (not shown). F.S.
and a transmitting circuit that adds a frame signal F and a DC signal B to the data signal and control signal S transmitted from the terminal device DTE, generates a subscriber burst 13s, and sends it to the subscriber sound line SL via the driver DV. SD and
and a burst timing circuit BT that determines the sending timing of the subscriber burst Bs to the subscriber line SL based on the synchronization mode switching signal MX independently or in dependence on the station burst (Bs) Bo transmitted from the digital subscriber circuit DLC. , and the digital subscriber circuit DLC extracts the clock signal on the home equipment SE side from the subscriber burst Bs received by the receiver R, which receives the subscriber burst Bs arriving from the subscriber line SL, and the receiver RV, and converts it into a digital signal. A bit synchronization circuit BS that synchronizes clock signals in the subscriber circuit DLC and a subscriber purse received by the receiver RV) B
The elastic store BS temporarily accumulates the frame signal F, extracts it using the station clock signal, and transmits it to the frame synchronization circuit FS, and detects the frame signal F from the subscriber burst Bs transmitted from the elastic store ES and outputs the data signal and The control signal S is separated and connected to a network NW (not shown).
frame synchronization circuit FS and network NW
A transmitting circuit SD generates a station burst BO by adding a frame signal F and a DC balance pin 1-B to the data (M number and control signal S) transmitted from the station, and sends it to the subscriber line SL via a driver DV. The transmission timing of the station berth I-BO to the subscriber line SL is determined by the synchronous mode switching signal MX.
and a Hurst timing circuit BT which determines the timing independently or dependently on the subscriber burst t-Bs transmitted from the digital line termination device DSU. In FIGS. 1 and 4, in the no-call state, the synchronous mode switching signals MX in the digital line termination unit DSU and the digital subscriber circuit DLC are both set to the dependent synchronous mode Fair. In such a case, the burst timing circuit BT of the digital line termination unit DSU does not instruct the transmission timing of the subscriber Hurst Bs unless the station burst BO arrives, and the burst timing circuit BT of the digital subscriber circuit I]LC also joins. The sending timing of the station burst BO is not specified until the station burst Bs arrives. Therefore, in the no-call state, transmission of both the office burst Bo and the subscriber base I-B s is stopped. The terminal device D TE enters the calling state, the synchronous mode switching signal MX is set to independent synchronous mode, and the transmission start signal ss
'r is digital times 1j! When transmitted to the terminating device D S tJ, the burst timing circuit BT in the digital line terminating device D S U switches from the dependent synchronous mode to the independent synchronous mode, and determines the sending timing of the subscriber burst (Bs) for each burst period Tb. Decide independently and send times! &S
D and the switching circuit SW. Based on the sending timing, the sending circuit SD sends the generated subscriber burst Bs to the subscriber line SL via the driver DV, and the switching circuit SW blocks the input of the subscriber burst Bs to the receiver RV. . The subscriber burst Bs arrives at the digital subscriber circuit DLC via the subscriber line SL. The bit synchronization circuit BS in the digital subscriber circuit DLC extracts a signal from the subscriber burst [3s] received by the receiver RV and transmits it to the burst detection circuit BD. Burst detection circuit +3 D is subscriber burst B
7 to addition consideration by extracting the frame signal F from s.
B) Detects the arrival timing of Bs and transmits it to the ζ burst timing circuit +37, and displays the burst detection signal Bd on a signal scanning circuit of an exchange (not shown). Further, the burst timing circuit BT determines the sending timing of the station burst BO based on the arrival timing and transmits it to the transmitting circuit SD. The transmitting circuit SD transmits the generated station parse Bo to the subscriber line SI via the driver DV based on the transmitting timing transmitted from the burst timing circuit BT. When the call ends, the transmission start signal SST transmitted from the terminal device DTE stops, and the synchronous mode switching signal MX returns to the slave synchronous mode again, the burst timing circuit BT
stops transmitting the sending timing of the subscriber burst hBs, and the transmission circuit SD stops transmitting the subscriber burst BS. As a result, the digital subscriber circuits Dl, C also stop transmitting the station burst BO. Next, from the network NW to the digital subscriber circuit DLC
When a call arrives, the synchronous mode switching signal MX is set to independent synchronous mode, and the transmission start signal SST is transmitted to the digital subscriber circuit DLC, the digital subscriber circuit DL
The burst timing circuit BT in C is switched from the dependent synchronization mode to the independent synchronization mode, and independently determines the sending timing of the station burst Bo for each burst period Tb, and the transmission circuit S
D and the switching circuit SW. Based on the transmission timing, the transmitting circuit SD sends the generated station burst Bo to the driver D.
V to the subscriber line SL, and the switching circuit SW blocks the input of the station burst Bo to the receiver RV. The station parse) Bo arrives at the digital line termination device D S tJ via the subscriber line SL. The bit synchronization circuit BS in the digital line termination unit DSU is connected to the receiver RV.
receives (N t ) The clock signal is extracted from the station burst Bo and transmitted to the frame synchronization circuit FS, and the frame synchronization circuit FS detects the arrival timing of the station burst Bo by extracting the frame signal F from the station burst Bo. The burst timing circuit BT, which is set to the dependent synchronization mode, determines the sending timing of the subscriber's purse (Bs) based on the arrival timing of the station burst BO transmitted from the frame synchronization circuit FS. and transmits it to the transmission circuit SD. Transmission circuit SD
is based on the transmission timing transmitted from the burst timing circuit BT, and transmits the generated subscriber burst Bs to the driver D.
V to the subscriber line SL. Therefore, the subscriber transmission system in the incoming call state is the same as that shown in FIG. When the call ends, the transmission start signal SST transmitted from the network NW stops, and the synchronous mode switching signal MX returns to the dependent synchronous mode again, the burst timing circuit BT stops transmitting the sending timing of the station burst Bo. , transmission circuit S
D stops transmitting the station burst BO. As a result, the digital line termination unit DSU also stops transmitting the subscriber's purse (Bs). As is clear from the above description, according to this embodiment, when a call is made, the digital line termination unit DSU
When a call arrives, the digital subscriber circuit DLC independently determines when to send out Bs.
It is no longer necessary to send both the station burst Bo and the station burst Bo, and the power of the digital subscriber circuit DLC can be reduced and the noise level caused by crosstalk from the subscriber line SL to other subscriber lines (not shown) can also be reduced. Note that FIGS. 1 and 4 are only one embodiment of the present invention, and the configurations of the digital line termination unit DSU and the digital subscriber circuit DLC are not limited to those shown in the figures, and other configurations may be used. Although many variations are considered,
In either case, the effects of the present invention remain the same. Further, the configurations of the subscriber burst 13g and the station burst BO are not limited to those shown in the drawings, and many other modifications may be considered, but the effects of the present invention will not change in any case. Furthermore, it goes without saying that the subscriber transmission system to which the present invention is applied is not limited to that shown in the drawings.

【Effect of the invention】

As described above, according to the present invention, in the two-wire time-division transmission system subscriber line, the digital subscriber circuit and the digital line termination device can both stop transmitting station bursts and subscriber bursts in a no-call state. , it becomes possible to reduce reactive power consumption in digital subscriber circuits and the noise level imparted to adjacent subscriber lines.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a digital subscriber line burst transmission/reception system according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a subscriber transmission system to which the present invention is applied, and FIG. FIG. 4 is a diagram showing an example of the subscriber line transmission method in FIG. 1. In the figure, B is a DC balance bit, BD is a burst detection circuit, BO is a station burst, Bs is a subscriber burst,
BS is a bit synchronization circuit, BT is a burst timing circuit, D is a data signal, DLC is a digital subscriber circuit, D
SU is digital line termination equipment, DTE is terminal equipment, D
V is the driver, BS is the elastic store, EX is the exchange, F is the frame signal, FS is the frame synchronization circuit, M
X is frame synchronization mode switching signal, RV is receiver 1
S is a control signal, SD is a transmission circuit, SE is a home device, SL
is a subscriber line, SST is a transmission start signal, and 'r b is a burst period. Qin 1st Warmth year 3rd year)

Claims (1)

[Claims] In a two-wire time-division transmission system subscriber line in which a digital subscriber circuit and a home device connected by a two-wire subscriber line transmit burst signals to each other in a time-division manner at a predetermined period, the home device Means for independently determining the burst signal sending timing of the own device when a call is made, and means for detecting the burst signal transmitted from the digital subscriber circuit when the call is received, and the timing of the burst signal sending of the own device based on the arrival time of the burst signal. The digital subscriber circuit is provided with means for independently determining the burst signal transmission timing of its own device when a call is received, and means for detecting a burst signal transmitted from the home device when a call is made and detecting the burst signal. 1. A digital subscriber line burst transmission/reception system, characterized in that it is provided with means for determining the signal transmission timing.