JPH0276430A - Initial leading-in system additionally having reverse training signal detecting function - Google Patents

Abstract

PURPOSE:To start leading-in operation after detecting a reverse training signal by providing the title system with a reverse training signal detecting function for detecting a reverse training signal sent from the subscriber side. CONSTITUTION:A station side 1 sends a training signal to the subscriber side and the subscriber side 2 detects the sent signal by a training signal detecting circuit 3 and executes the leading-in operation of an equalizer, a PLL or the like. After setting up synchronism, a reverse training signal is sent to the station side 1. The station side 1 opens a window in a receiving part by a receiving window signal only by the arrival period of the reverse training signal independently of a distance and detects the existence of the reverse training signal by a reverse training signal detecting circuit 1. When the circuit 3 can detect N bursts continuously M times, the reception of a real reverse training signal different from an artificial reverse training signal is recognized and the leading-in control of the equalizer, the PLL or the like in the station side 1 can be started.

Description

DETAILED DESCRIPTION OF THE INVENTION (Summary) This invention relates to an initial pull-in method in which a reverse training signal detection function is added in a digital subscriber line ping-pong transmission method.

The purpose of the present invention is to provide an initial pull-in method with an additional reverse training signal detection function that starts pull-in after confirming the detection of the reverse training signal transmitted after synchronization is established on the subscriber side.

A training signal is transmitted from the station side to the subscriber side.

A training signal detection circuit is provided on the subscriber side to detect a training signal transmitted from one station in the initial pull-in method of the digital subscriber line ping-pong transmission system that establishes synchronization, and a training signal detection circuit is provided on the subscriber side to detect a training signal transmitted from one station side. A reverse training signal detection circuit is provided on the station side to detect a reverse training signal transmitted from the subscriber side after synchronization is established on the subscriber side, and the reverse training signal sent from the station side after synchronization on the subscriber side is established. The system is configured to start pull-in control on the two-station side after confirming signal detection.

[Industrial application field]

The present invention relates to an initial pull-in method that includes a reverse training signal detection function in a digital subscriber line ping-pong transmission method.

Prior to starting communication, signals are exchanged between the three stations and the subscriber to establish synchronization.

It is desired that synchronization between the two be reliably established without erroneous pull-in due to noise or the like.

[Conventional technology]

In the conventional digital subscriber line transmission system, synchronization is established between the two stations and the subscriber side in the time-division direction control transmission system, which temporally separates the upstream and downstream communications, that is, the ping-pong transmission system. In order to
As shown in the figure, a training signal is first sent from the office side to the subscriber side, and synchronization is established on the subscriber side based on the training signal.

A time t, which is longer than the estimated time t1 for returning the reverse training signal to the station, is set on a timer, and the end of the timer time t is used as a trigger for starting pull-in on the station side.

(Problem to be solved by the invention) Therefore, since the three stations use timers to uniformly set the time t from when the training signal is sent to when the inverse training signal is returned, there is no cause for concern. There was a pull-in failure on the subscriber side, synchronization establishment on the subscriber side was not performed normally, and 1<1. In this case, even though no reverse training signal has come from the subscriber side, the first station automatically starts pulling in at the end of the timer time t, causing a problem between the first station and the subscriber. There was a drawback that synchronization could not be established.

The present invention is aimed at solving the above-mentioned drawbacks, and is intended to perform reverse training so that pull-in control on the two stations starts after confirmation of detection of the reverse training signal transmitted after synchronization is established on the subscriber side. The purpose is to provide an initial pull-in method with an added signal detection function.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, 1 is the station side, which transmits a training signal from the subscriber line exchange to a designated subscriber and establishes synchronization with the subscriber side, and 2 is the subscriber side, which is the one that transmits training signals from the subscriber line exchange to the specified subscriber. 1 equalizer receives the training signal transmitted from side 1, P
LL, etc., and transmits a reverse training signal to the station side 1 after synchronization is established. 3 is a training signal detection circuit that detects the training signal transmitted from the 1 station side 1. 4 is a reverse training signal. The training signal detection circuit detects a reverse training signal sent after synchronization of the subscriber side 2 is established, and 5 is a two-line subscriber line.

(Function) Since it is a ping-pong transmission system, a transmission/reception switching signal (S/R) is always output from the station side 1 as shown in Fig. 4.Line conditions of the 2-line subscriber line 5 used In other words, since there is a time lag in the reverse training signal transmitted from the subscriber side 2 during the reception period of the station side L depending on the distance, the reception wind signal is always received only during the period when the reverse training signal is received, regardless of the distance. Open the receiver window and detect whether there is a reverse training signal (100% comparator output), N bursts consecutively, M
If it can be detected, it is assumed that the reverse training signal has been returned, and the pull-in control of the second station 1 is started.

〔Example〕

FIG. 2 shows the configuration of one embodiment of the station-side device.

In the figure, 6 is a switch interface section, 7 is a line termination section,
8 is a transmission line termination part, 9 is a current source, IO is a power supply switch,
11 is a reception window signal generator.

Reference numeral 12 represents a receiving section, 13 a transmitting section, and 14 a transmitting/receiving level setting section.

FIG. 3 shows the configuration of an embodiment of the subscriber side equipment.

In the figure, 15 is a terminal interface section, 16 is a line termination section, 17 is a transmission line termination section, 1B is a power reset section, 19
2 represents a DC/DC converter, 20 a transmitter, 21 a receiver, 22 a reception window signal generator, and 23 a transmit/receive level setting unit.

In one embodiment of the configuration of the station-side device and the subscriber-side device shown in FIGS. 2 and 3, when an incoming call to a specific subscriber reaches the line termination unit 7 via the exchange interface unit 6, the line termination unit In order to transmit a training signal for establishing synchronization to the subscriber side 2 during the time-division transmission period, the unit 7 turns on the power supply switch 10 to supply power from the current source 9 to the subscriber side 2, and also receives power from the transmitter 13. A training signal is transmitted to the subscriber side 2 via the transmission/reception level setting section 14. At this time, the reception window signal generator 11 is reset at the same time.

On the subscriber side 2, the power transmitted from the 1 station side 1 is connected to D.
The C/DC converter 19 converts it to a predetermined voltage.

A predetermined voltage is supplied to each part via the power supply reset part 18. The power supply reset unit 18 simultaneously sends a heliset signal to the receiving wind signal optical generator 22 during the time-division transmission period from the station side 1 to the subscriber side 2.

A reception window signal generating section 22 generates a reception window signal that opens the reception section 21 for a fixed period unrelated to the above-mentioned distance. As a result, the receiving section 21 receives the training signal transmitted from the station side 1 via the transmission/reception level setting section 23, extracts a synchronization signal based on the training signal, and sets the synchronization clock of the subscriber side 2 as shown in the figure. The clock is generated by a synchronous clock generation circuit that does not have a synchronous clock, and synchronization of the equalizer, PLL, etc. is established.

When synchronization is established on the subscriber side 2, the subscriber side 2 receives information from the transmitter 20 via the transmission/reception level setting unit 23 during the time-division transmission period of the subscriber side 2, that is, during the reception period on the station side l. A reverse training signal indicating that synchronization has been established is transmitted to the station side l.

On the station side 1, the reception window signal generating section 11 is reset, and after a certain period of time has elapsed, a reception window signal is generated that causes the reception section 12 to open for a certain period of time unrelated to the above-mentioned distance during the reception period of the station side 1. Reception window signal generator 1
It is designed to be generated from 1. During the period when the receiving section 12 is open, the receiving section 12 detects whether a reverse training signal from the subscriber side 2 is being received via the transmission/reception level setting section 14.

Therefore, if the receiver 12 is able to detect N bursts 9M times in a row, it is assumed that a genuine inverse training signal has been received, not a pseudo inverse training signal due to noise, and the equalizer, PLL, etc. of the second station side 1 are Control begins.

Since the operation is the same as the conventional one except for the initial pull-in, the explanation thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, the subscriber side detects the training signal transmitted from the station side as a trigger to start pull-in, and the station side detects the training signal transmitted from the subscriber side after synchronization is established. Since the signal is detected and the pull-in is started after the detection is confirmed, synchronization can be reliably established between the one station side and the subscriber side.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 shows the configuration of an embodiment of the station-side device. FIG. 3 shows the configuration of an embodiment of the subscriber side equipment. FIG. 4 is a time chart on the station side of the present invention. FIG. 5 is a conventional time chart on the station side. In the figure, l...office side, 2... subscriber side, 3... training signal detection circuit, 4... reverse training signal detection circuit, 5... 2-line subscriber line, 6... - Exchange interface section, 7... Line termination section, 8... Transmission line termination section, 9-1 〇-... Current source, 10... Power supply switch, 11... Reception window signal generation section, 12...receiving section, 13...
Transmission section. 14... Transmission/reception level setting section, 15... Terminal interface section, 16... Line termination section, 17... Transmission line termination section, 18... Power supply reset section, 19... DC/
DC conversion section, 20... Transmission section, 21... Receiving section, 2
2... Reception window signal generation section, 23... Transmission/reception level setting section.

Claims (1)

[Claims] In an initial pull-in method of a digital subscriber line ping-pong transmission system in which a training signal is transmitted from the station side (1) to the subscriber side (2) and synchronization is established, the transmission is made from the station side (1). A training signal detection circuit (3) for detecting the received training signal is provided on the subscriber side (2), and a training signal detection circuit (3) for detecting the received training signal is provided on the subscriber side (2).
) is established, a reverse training signal detection circuit (4) for detecting a reverse training signal transmitted from the subscriber side (2) is provided on the station side (1), and An initial pull-in method with an added reverse training signal detection function, characterized in that pull-in control on the station side (1) is started after confirmation of detection of a reverse training signal transmitted after synchronization is established.