JPH042241A - Burst signal control system - Google Patents

Abstract

PURPOSE:To surely establish frame synchronization even when a high level crosstalk signal is leaked from an adjacent subscriber line by providing a means to eliminate the crosstalk signal from a reception signal arriving from a subscriber line when the crosstalk signal is detected. CONSTITUTION:A transmission signal stop means 100 stops the transmission of a signal for a predetermined time to a subscriber line 1 in the case of starting communication. In the start of communication, a crosstalk signal detection means 200 detects the presence of a crosstalk signal from other subscriber line while no signal is sent from an intra-office equipment 2. When a crosstalk signal elimination means 300 eliminates a crosstalk signal from the reception signal arriving from the subscriber line 1 when the crosstalk signal detection means 200 detects the crosstalk signal. Moreover, upon the detection of the crosstalk signal, the crosstalk signal detection means 200 informs the detection of the crosstalk signal to the intra-office equipment 2. Thus, a subscriber's equipment 3 surely establishes frame synchronization based on the reception signal from which the crosstalk signal is eliminated.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a burst signal control method that makes it possible to eliminate the effects of crosstalk signals in a two-wire subscriber line that employs a time-division direction control transmission method. A two-wire subscriber system that connects in-office equipment and in-home equipment and adopts a time-division direction control transmission method, with the aim of making it possible to reliably establish frame synchronization even when the level of crosstalk signals crosstalk. In the subscriber line °ζ, the in-office equipment is provided with a transmission signal stopping means for stopping the transmission of signals to the subscriber line for a predetermined time when communication is started,
A crosstalk signal detection means detects the presence or absence of a crosstalk signal from another subscriber's line when a communication is started, and the crosstalk signal detection means detects a crosstalk signal while no signal is being sent from the in-house equipment. The crosstalk signal removing means removes the crosstalk signal from the received signal arriving from the subscriber line when the crosstalk signal is detected. The transmission signal stopping means is configured to notify the detection of a crosstalk signal, and the transmission signal stopping means stops the signal to the subscriber line without waiting for a predetermined time when the crosstalk signal detection means notifies the detection of the crosstalk signal. Configure to start sending.

[Industrial application field]

The present invention relates to a burst signal control method that makes it possible to eliminate the influence of crosstalk signals in a two-wire subscriber line that employs a time-division direction control transmission method.

For example, in a two-wire subscriber line of an integrated service digital communication network, a time-division direction control transmission method that transmits bidirectional signals in a time-division manner is used to transmit and receive digital signals between in-office equipment and in-home equipment. (-salt ping-pong transmission method) is adopted.

[Conventional technology]

FIG. 7 is a diagram showing an example of a conventional two-wire subscriber line, FIG. 8 is a diagram showing an example of a receiving circuit of the in-home equipment in FIG. 7, and FIG. 9 is a diagram showing a conventional calling process. FIG. 10 is a diagram showing an example of a conventional call receiving process.

In FIG. 7, a two-wire subscriber line 1 is terminated by an in-house device 2 inside the office, and terminated by an in-home device 3 inside the home.

In the in-office device 2, the processing circuit 21 performs a predetermined cycle (frame) using a transmission/reception switching signal sw supplied from the outside.
During the transmission period when the transmission/reception changeover switch 24 is switched to the transmission circuit 22 side, the signal output from the transmission circuit 22 is switched alternately to the transmission circuit 22 side and the reception circuit 23 side. During the receiving period when the signal is transmitted to the subscriber line 1 and the transmission/reception changeover switch 24 is switched to the receiving circuit 23 side, the receiving circuit 23 receives the signal arriving from the subscriber line 1 .

Further, in the home device 3, the receiving circuit 33 is connected to the home device 2.
detects a frame from a signal transmitted via the subscriber line 1, and the processing circuit 31 alternately switches the transmission/reception selector switch 34 to the transmitting circuit 32 side and the receiving circuit 33 side in synchronization with the detected frame, During the transmission period when the transmission/reception changeover switch 34 is switched to the transmission circuit 32 side (reception period of the in-office device 2), the signal output from the transmission circuit 32 is sent to the subscriber line 1, and the transmission/reception changeover switch 34 receives the signal. During the reception period when the circuit 33 side is switched (the transmission period of the in-office device 2), the signal arriving from the subscriber line 1 is sent to the reception circuit 3.
Received by 3.

In FIGS. 7 to 9, when the subscriber line 1 is in a non-communication state, a predetermined DC voltage ■1 is supplied from the in-office device 2 to the in-home device 3 via the subscriber line 1. ing. However, almost no direct current is supplied.

In such a state, when a call occurs to the home device 3 and the calling signal a is transmitted to the inside office f2 via the subscriber line l, the home device 2 converts the DC voltage Vl supplied to the home device 3 into Switching to the DC voltage 2 with the opposite polarity and starting supplying a predetermined DC current, the transmission circuit 22 sends a predetermined training signal to the home via the transmission/reception switch 24 and the subscriber line 1. The information is transmitted to device 3.

In the home device 3, the variable gain equalization circuit 331 in the reception circuit 33 transmits the training signal transmitted from the home device 2 via the subscriber line 1 to the transmission/reception changeover switch 34.
When received via the variable gain vase 33, the comparison circuit 3313 and the gain control circuit 3314 equalize the received signal to a predetermined equalization reference level L2, and then the comparison circuit 3312 equalizes the reproduction discrimination level. The received signal is regenerated using L1 as a reference, and the regenerated training signal is transmitted to the frame synchronization circuit 332.

The frame synchronization circuit 332 detects frames based on the training signal transmitted from the variable gain equalization circuit 331.

When frame synchronization is established as described above, the in-home device 3 transmits the training completion signal C to the in-office device 2 via the subscriber line 1.

Thereafter, the in-office device 2 and the in-home device 3 start communication d via the subscriber line 1 using the time division direction control transmission method.

Next, in FIGS. 7, 8, and 10, the subscriber line 1 is in a non-communication state and the DC voltage v1 is being supplied to the home device 3 via the subscriber line 1 as described above. in,
When the incoming call to the in-home device 3 occurs in the in-office device 2, the in-office device 2 switches the DC voltage v1 supplied to the in-home device 3 to the DC voltage ■2, starts supplying a predetermined DC current, and starts transmitting. A predetermined training signal is transmitted from the circuit 22 to the home device 3 via the transmission/reception changeover switch 24 and the subscriber line 1.

After that, the home device 3 equalizes the received signal and establishes frame synchronization in the same process as when making a call, and then communicates d between the home device 2 and the home device 3 via the subscriber line 1. Start.

If multiple subscriber lines of this type are installed adjacent to each other,
Crosstalk occurs between subscriber lines.

FIG. 11 is a diagram showing an example of subscriber lines accommodated in the same quad, and FIG. 12 is a diagram showing an example of various conventional signal waveforms.

In FIGS. 11 and 12, two subscriber lines 1 (one is called LA and the other is called 1., the same applies hereinafter) are accommodated in the same quad 4, and one in-office equipment 2A and When the device 3A is communicating via the subscriber line 1, the home transmission signal SSa is transmitted during the transmission period of the home device 3A.
is sent to the subscriber line IA with almost no attenuation, and during the reception period of the home equipment 3.0, the home reception signal SIA is
It arrives from subscriber line IA in a sufficiently attenuated state.

At this time, the other in-office device 21 starts communication, and the subscriber line 1. When the training signal starts to be sent to the home device 3. The training signal arrives from the subscriber line 1 in a sufficiently attenuated state as the in-home reception signal S1m.
The home transmission signal SSA being transmitted on the subscriber line LA is transmitted to the subscriber line 1. crosstalk, and in-home reception signal 5 as crosstalk signal X1m
i11, the reception circuit 33.i1 in the home device Sll. In , when the variable gain transmitter 3311m equalizes the subscriber line signal Sl based on the equalization reference level Lx and outputs the equalized reception signal SEW, the crosstalk signal X1ll+
is equalized at the same time and output as the equalized crosstalk signal
At the same time, the equalized crosstalk signal X■ is also identified for reproduction by the reproduction identification level L, and the reproduced crosstalk signal XCI is outputted and transmitted to the frame synchronization circuit 332m. The frame cannot be reliably detected, and frame synchronization between the in-office device 2 and the in-home device 3 cannot be established, making communication impossible.

[Problem to be solved by the invention]

As is clear from the above description, in a conventional two-wire subscriber line, crosstalk signals XI1. If there is crosstalk, it becomes difficult to establish frame synchronization at the start of communication, making communication impossible.

An object of the present invention is to ensure that frame synchronization can be established even when high-level crosstalk signals are generated from adjacent subscriber lines.

[Means to solve the problem]

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

In FIG. 1, ``■'' is a two-wire subscriber line that employs a time-division direction control transmission system, 2 is an in-office device, and 3 is an in-home device.

100 is a transmission signal stop means provided in the in-office device 2 according to the present invention.

200 is crosstalk signal detection means provided in the home device 3 according to the present invention.

Reference numeral 300 denotes crosstalk signal removal means provided in the home device 3 according to the present invention.

[Operation] The transmission signal stop means 100 stops sending signals to the subscriber line 1 for a predetermined time at the start of communication.

The crosstalk signal detection means 200 detects the presence or absence of a crosstalk signal from another subscriber line while no signal is being sent from the in-office device 2 at the start of communication.

The crosstalk signal removing means 300 removes the crosstalk signal from the received signal arriving from the subscriber line 1 when the crosstalk signal detecting means 200 detects a crosstalk signal.

Note that, when the crosstalk signal detection means 200 detects a crosstalk signal, it is also considered that the crosstalk signal detection means 200 notifies the in-office device 2 of the detection of the crosstalk signal.

Further, the transmission signal stopping means 100 includes the crosstalk signal detecting means 20
It is also possible to start transmitting a signal without waiting for a predetermined time when a crosstalk signal detection notification is received from 0.

Therefore, the home device can reliably establish frame synchronization based on the received signal from which the crosstalk signal has been removed, improving the reliability of the subscriber line.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing an example of a two-wire subscriber line according to an embodiment of the present invention, FIG. 3 is a diagram showing an example of a receiving circuit of the in-home equipment in FIG. 2, and FIG. FIG. 5 is a diagram showing an example of the calling process in FIG. 2; FIG. 5 is a diagram showing an example of the call receiving process in FIG. 2; FIG. 6 is a diagram showing various signal waveforms according to an embodiment of the present invention. It is a diagram. Note that the same reference numerals indicate the same objects throughout the figures.

2 and 3, a signal transmission control section 211 is provided in the in-office device 2 as the transmission signal stop means 100 in FIG. 1, and a crosstalk signal identification circuit 354 is provided as the crosstalk signal detection means 200 in FIG. is provided in the receiving circuit 35 in the home device 3, and a mask signal generation circuit 355 and a logic circuit 356 are provided in the receiving circuit 35 in the home device 3 as the crosstalk signal removing means 300 in FIG.

In FIGS. 2 to 6, the subscriber line 1 shown in FIG. One in-office device 2A and one in-home device 3
When A is communicating via the subscriber line IA, the home transmission signal SSa is transmitted during the transmission period of the home device 34, as described above.
is transmitted to the subscriber line IA with almost no attenuation, and the in-home equipment 3. During the reception period, the in-house reception signal SRA is
It arrives from subscriber line IA in a sufficiently attenuated state.

At this time, a call occurs to the other home device 311, and the call is made from the home device 3m to the subscriber line 1. The calling signal a is transmitted to the in-office device 2m via the in-office device 2m, or the calling signal a is transmitted to the in-office device 2m via the in-office device 2m. When an incoming call occurs to the home device 3m at 1, the home device 21 changes the DC voltage 1 sent to the subscriber line IB to 2, as described above.
2, and starts supplying a predetermined DC current to the in-home device 3m via the subscriber line 13, but the processing circuit 21
A signal transmission control section 211 within the system prevents the training signal from being transmitted for a predetermined period of time.

As a result, only the crosstalk signal XR11 from subscriber lineman 1. It is transmitted to the interior of the house W 3 II via.

In the home device 3m, the receiving circuit 35. The variable gain equalization circuit 3318 in subscriber line 1. The crosstalk signal XRII arriving from is received via the transmission/reception changeover switch 34B, is equalized to the equalization reference level L2 by the variable gain vase 3311g, the comparison circuit 3313g, and the gain control circuit 3314g, and is output as the equalized crosstalk signal XEB to the comparison circuit 3312m. Equalized crosstalk signal X transmitted to and received by comparison circuit 3312++
E, l are reproduced based on the reproduction identification level LI, and the crosstalk signal identification circuit 354B and the logic circuit 356. to communicate.

Note that before the start of communication, the crosstalk mask signal Mm output by the mask signal generation circuit 355M is held at logic "0", so the logic circuit 356M is in a cut-off state, and the crosstalk mask signal Mm is transmitted from the variable gain equalization circuit 331. Regenerated crosstalk signal XCI is transmitted to frame synchronization circuit 332m and data processing circuit 333.
is not transmitted.

The crosstalk signal identification circuit 354B is composed of a monostable multivibrator and a counting circuit, and analyzes whether the received reproduced crosstalk signal Xe1l is a burst signal having a predetermined period (i.e., frame), If the signal is identified as such, it is determined that the reproduced crosstalk signal Xl:I has been identified, and the reproduced crosstalk signal XCI is transmitted to the mask signal generation circuit 355B.

The mask signal generation circuit 355B is composed of a monostable multi-by-break and a shift register, and extends and shifts the burst length of the received regenerated crosstalk signal XCI to sufficiently cover the reception period of the regenerated crosstalk signal XCB as shown in FIG. generates a crosstalk mask signal M that is set to logic "0" in the range where the signal is applied, and is set to logic "1" in the other range, and transmits it to the logic circuit 356.
The processing circuit 3111 is notified that the crosstalk signal X□ has been identified.

The processing circuit 311 that received the crosstalk signal identification notification processes the subscriber line 1. In-office equipment 2. The identification end signal e is transmitted to.

In-office device that received the identification end signal e2. is subscriber line 1
．． Start sending out training signals.

As a result, the in-home device 3 is connected to the in-house device 2 in the same manner as described above.
When the sufficiently attenuated training signal b (-home reception signal S+u+) transmitted from the home apparatus 31 and the crosstalk signal X■ are alternately received, the receiving circuit 33. In the same process as described above, the reproduced received signal 5cII and the reproduced crosstalk signal Xel
and the crosstalk signal identification circuit 354 . and logic circuit 3
Transmit to 56 lines.

Logic circuit 356. The crosstalk mask signal Mm received from the mask signal generation circuit 355 is set to logic “0” during the period in which the logic circuit 356B receives the reproduced crosstalk signal XCI from the variable gain equalization circuit 3318, and
1. The period during which the reproduced reception signal 5CIl is received from the logic “
1'', only the reproduced reception signal 5cll is output from the logic circuit 356B via the logic circuit 356□, which is set to a conductive state, and the frame synchronization circuit 332 and the data processing circuit 333. transmitted to.

The frame synchronization circuit 332B receives only the reproduced reception signal S■ and reliably detects the frame.

When frame synchronization is established through the above steps, the home device 3. transmits the training completion signal C to the in-office device 28 via the subscriber line 1+i, and thereafter transmits the training completion signal C to the in-office device 2B and the in-home device 3.
．． starts communication d using the time division direction control transmission method via the subscriber line IB.

Please note that subscriber line 1. While the crosstalk signal XRII from the home device 3.B is at a sufficiently low level and the home device 2B stops transmitting the training signal, the home device 3.B. cannot identify the crosstalk signal XRI+, the mask signal generation circuit 355
After the period during which the in-office device 2B stops transmitting the training signal has elapsed, Il changes the crosstalk mask signal M8 to logic
The setting is maintained at 1P, and the logic circuit 356. Set to constant conduction.

When the in-house device 2B starts transmitting the training signal S after a predetermined period of time has elapsed, the in-home device 3m equalizes and reproduces the received in-house reception signal S■ through the same process as described above, but the crosstalk signal X1ll is reproduced and identified. Since it is below the level L, it is not reproduced, and only the reproduced reception signal SCI is output from the logic circuit 356m set to a conductive state, and sent to the frame synchronization circuit 332 and the data processing circuit 333B.
transmitted to.

As is clear from the above description, according to this embodiment, while the in-office device 211 stops transmitting the training signal at the start of communication, the in-home device 3Il identifies the presence or absence of the crosstalk signal χ□, and transmits the crosstalk signal XRB. When it is identified, the crosstalk signal X1ll (more precisely, reproduced crosstalk signal Xcll) is removed by the crosstalk mask signal Ma+, so the high level crosstalk signal X1m is removed.
Frame synchronization can be established quickly and reliably even when data is leaked.

Note that FIGS. 2 to 6 are only one embodiment of the present invention, and, for example, the home device 3B that has identified the crosstalk signal XRB is limited to one that returns an identification end signal e to the home device 1F28. Although it is considered that the in-office device 2B always stops transmitting the training signal for a predetermined period and then starts transmitting the training signal, the timing of starting transmitting the training signal is only slightly delayed. The effect remains unchanged. The configurations of the in-office device 2, the in-home device 3, and the receiving circuit 35 are not limited to those shown in the drawings, and many other modifications may be considered, but the effects of the present invention remain the same in any case. Also, subscriber line 1. The various signal waveforms in the upper and receiving circuits 3511 are not limited to those shown, and many other modifications may be considered, but the effects of the present invention remain the same in any case.

〔Effect of the invention〕

As described above, according to the present invention, in the two-wire subscriber line, the home device can reliably establish frame synchronization based on the received signal from which the crosstalk signal has been removed, and the reliability of the subscriber line is improved. do.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing an example of a two-wire subscriber line according to an embodiment of the present invention, and FIG. 3 is an example of the reception circuit of the home equipment in FIG. 2. Figure 4 showing
FIG. 5 is a diagram showing an example of the calling process in FIG. 2, FIG. 5 is a diagram showing an example of the call receiving process in FIG. 2, and FIG. 6 is a diagram showing various signal waveforms according to an embodiment of the present invention. Fig. 7 is a diagram showing an example of a conventional two-wire subscriber line, Fig. 8 is a diagram showing an example of the reception circuit of the home equipment in Fig. 7, and Fig. 9 is a diagram showing an example of the conventional call origination process. 10 shows an example of a conventional call reception process, FIG. 11 shows an example of subscriber lines accommodated in the same quad, and FIG. 12 shows an example of various conventional signal waveforms. It is a diagram. In the figure, 1 is a subscriber line, 2 is an in-office device, 3 is an in-home device, 4 is a quad, 21 and 31 are processing circuits, 22 and 32 are transmitting circuits, 23, 33 and 35 are receiving circuits,
24 and 34 are transmission/reception changeover switches, 100 is a transmission signal stop means, 200 is a crosstalk signal detection means, 211 is a signal transmission control section, 300 is a crosstalk signal removal means, 331 is a variable gain equalization circuit, 332 is a frame synchronization circuit, 333 is a data processing circuit, 354 is a crosstalk signal identification circuit, 355 is a mask signal generation circuit, 356 is a logic circuit, +3311 is a variable gain vase, 3312 and 3313 are comparison circuits, 33
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Record

Claims (3)

[Claims] (1) A two-wire subscriber line (1
), the in-office device (2) is provided with a transmission signal stop means (100) for stopping the transmission of the signal to the subscriber line (1) for a predetermined time when communication starts, and the in-house device (3) When starting communication, a crosstalk signal detection means (2) detects the presence or absence of a crosstalk signal from another subscriber line while no signal is being sent from the in-office device (2).
00), and crosstalk signal removing means (300) for removing the crosstalk signal from the received signal arriving from the subscriber line (1) when the crosstalk signal detecting means (200) detects a crosstalk signal. A burst signal control method featuring: (2) The burst signal according to claim 1, wherein the crosstalk signal detection means (200) notifies the in-office device (2) of the detection of the crosstalk signal when the crosstalk signal is detected. control method. (3) When the transmission signal stop means (100) is notified of the detection of the crosstalk signal by the crosstalk signal detection means (200), the transmission signal stop means (100) stops the transmission signal from the subscriber line (100) without waiting for the predetermined time. 2. The burst signal control system according to claim 1, wherein the burst signal control system starts transmitting a signal to the burst signal control system.