JPH0352349A - Burst signal control system - Google Patents

Abstract

PURPOSE:To prevent synchronizing step-out due to near end crosstalk by allowing each main communication signal to amplify the amplitude of a head signal of each transmission signal, sending the result, allowing each sub communication station to establish the frame synchronization of a reception signal in response to the amplitude of a head signal of each reception signal in excess of a burst detection level, thereby entering the communication. CONSTITUTION:Subscriber's equipments 20, 22 as sub communication stations and in-station equipments 26, 28 as main communication stations are connected via a 2-wire subscriber line 24 as a 2-wire transmission circuit. When the equipments 26, 28 send a transmission signal, the amplitude of the head signal of the transmission signal is amplified and sent. On the other hand, the subscriber's equipments 20, 22 establish the frame synchronization of a reception signal in response to the amplitude of the head signal of each reception signal in excess of the burst detection level and enters the communication. Thus, even when near end crosstalk takes place, the signal is sent and received surely without the effect of near end crosstalk.

Description

[Detailed description of the invention] [Summary] A burst signal that prevents frame synchronization caused by near-end crosstalk in a two-wire transmission line between a main communication station group and a sub communication station group using a signal from the main communication station side. Regarding the control method, the main communication station group and the sub communication station group are connected via a two-wire transmission line, with the aim of establishing frame synchronization by reliably identifying the burst signals sent from the main communication station. In a communication system in which signals are sent and received between each main communication station and each sub-communication station at regular intervals, each main communication station increases the amplitude of the leading signal of each transmission signal and sends it to each sub-communication station. The system established frame synchronization of the received signals and started communication in response to the amplitude of the leading signal of each received signal exceeding the burst detection level.

[Industrial application field]

The present invention relates to a burst signal control system, and particularly to a burst signal control system that prevents frame synchronization caused by near-end crosstalk in a two-wire transmission line between a main communication station group and a sub communication station group using a signal from the main communication station side. Regarding signal control methods.

[Conventional technology]

In a communication system using a telephone line, as shown in FIG. As shown in FIG. 8, there is a burst transmission method in which transmission and reception are performed at regular intervals between the in-office device 14 and the in-home device 10 and between the in-office device 16 and the in-home device 12. It is being done.

[Problem to be solved by the invention]

However, in the case of the conventional transmission system, when transmitting the transmission signal S from the home device 10 to the home device l4, near-end crosstalk occurs between the home device IO and the home device 12, as shown in FIG. However, if the level of this signal is below the reproduction identification level, the crosstalk signal will not be received by the home device l2, but if the level of the crosstalk signal exceeds the reproduction identification level,
The transmitted signal S is received as a received signal R' by the home device 12, and a reproduced signal based on the crosstalk signal R' is output to the home device 12. For this reason, normal frame synchronization may not be achieved in the residential interior Wl2.

An object of the present invention is to provide a burst signal control method that can reliably identify burst signals sent from a main communication station and establish frame synchronization.

[Means to solve the problem]

The present invention connects a group of main communication stations and a group of sub-communication stations via a two-wire transmission line, and transmits and receives signals between each main communication station and each sub-communication station at regular intervals (see Fig. 1). In a communication system that performs (see 1)), each main communication station increases the amplitude of the leading signal of each transmitted signal and sends it out, and each sub-communication station transmits the signal when the amplitude of the leading signal of each received signal exceeds the burst detection level. In response to this, frame synchronization of the received signal is established and communication begins. [Operation] The main communication station sends out a signal with the amplitude of the first signal of the transmitted signal increased (see (2) and (3) in Figure 1), and the sub communication station increases the amplitude of the first signal of the received signal. Frame synchronization is established in response to the amplitude exceeding the burst detection level, so even if near-end crosstalk occurs, the level of near-end crosstalk is below the burst detection level, so it is not transmitted from the main communication station to the sub-communication station. burst signals can be reliably identified.
This enables highly reliable transmission and reception.

〔Example〕

In FIG. 2, in-home devices 20 and 22 as sub-communication stations
and in-office devices 26 and 28 as a main communication station are connected via a two-wire subscriber line 24 as a two-wire transmission circuit. As shown in FIG.
Inverters 32, 34, selection circuits 36, 38, transistors TRI, TR2, TR3, TR4, TR5, TR6
, R1, R2, R3, and R4, and is configured to increase the amplitude of the leading signal of the transmit signal when transmitting the transmit signal from the output terminals Tl, T2. That is, the transmission data input to the U/B conversion circuit 30 (
When controlling the transmission signal based on the transmission clock (■ in Figure 4) and the transmission clock (■ in Figure 4), the transistors TRI and TR2 are turned on alternately when the transmission data is "1'' in synchronization with the clock signal. At the same time, when the synchronization is not achieved, the selection circuit 38 outputs the signal [phase] (same as the signal ■) as a selection signal (■ in FIG. 4) by the signal SYNC@ at the L1 level, and the selection circuit 36 Switch as indicated by the dotted line and press T.
Turn on R5 and TR6 alternately. transistor TR
5. When the TR6 is turned on (■.■ in FIG. 4), the amplitude of the transmission signal is increased and output to the subscriber line 24.

On the other hand, as shown in FIG.
2. It is equipped with a gate circuit 44, a frame synchronization circuit 46, and a data processing circuit 48, and the variable gain equalization circuit 40 is composed of a variable gain equalizer 50, a gain control 1ml [F52, a comparator 54, a comparator 56, The burst identification signal generation circuit 42 includes a comparator 58 and a burst identification signal generation circuit 60. A reception clock (2) is supplied to the gain control circuit 52 and the burst identification generation circuit 60.

As shown in FIG. 6, the level of the received signal input to the variable gain equalization circuit 40 is
4, 56 detects that the reproduction discrimination level has been exceeded, the gain control circuit 52 and the variable gain equalizer 50
is amplified to an equalization reference level signal. Further, the received signal inputted to the variable gain equalization circuit 40 is inputted from the variable gain equalization circuit 50 to the burst identification signal generation circuit 42. The comparator 58 determines whether the amplitude of the received signal exceeds the burst detection level, and when the amplitude of the leading signal exceeds the burst detection level, a burst detection signal (■ in FIG. 6) is output from the comparator 58. , a burst identification signal generation circuit 6 that receives the burst detection signal.
0 to burst identification signal (■ in Figure 6) for a certain period of time t
1, output to the gate circuit 44. Thereby, the reproduced signal input to the gate circuit 44 is transferred to the frame synchronization circuit 46 only for a certain period of time t1. Furthermore, even if a crosstalk signal due to near-end crosstalk is output to the variable gain equalization circuit 40, no burst identification signal is generated when the level of this signal is below the burst detection level. It will not be transmitted to.

When a reproduced signal is input to the frame synchronization circuit 46, frame synchronization is established, and a signal belonging to the same frame is sent from the data processing circuit 48 to the home device 20.2 as a reproduced signal.
It will be available for use in 4. In this way, when synchronization is achieved, the signal SYNC@ on the side of the station equipment becomes "H" level, the selection circuit 38 selects signal 0 (always "L" level), and the selection circuit 36 is switched to the normal drive side (solid line). .

In this way, in this embodiment, the in-office devices 26, 28
When transmitting and receiving signals between the station equipment 20 and 22, transmission and reception are performed at fixed intervals;
．． When transmitting a signal from 28, a signal whose amplitude at the beginning of the transmitted signal exceeds the burst detection level is output. And the interior of the house! In response to the head amplitude of the received signal exceeding the burst detection level at step 20.22, frame synchronization of the received signal is established and a reproduced signal is output. Therefore, even if near-end crosstalk occurs via the subscriber line 24, burst signals can be reliably identified, and highly reliable signals can be exchanged between the in-office equipment 26.28 and the in-home equipment 20.22. can be done.

In the above embodiment, the burst identification signal is input to the gate circuit 44, but the burst identification signal is input to the variable gain equalizer 50 or the converter 5.
4 to prevent crosstalk signals from being mixed into the equalized output. Furthermore, according to this embodiment, it is only necessary to increase the amplitude of only the beginning of the signal transmitted from the in-office equipment 26, 28 side and detect this on the in-home equipment 20, 22 side, so that the burst identification signal generation circuit is not required. 42 circuits can be constructed with simple ones.

Further, even if the amplitude is increased, only the leading signal is affected, so the equalizer 50 does not operate with this signal, but operates with the normal amplitude, so the operation of the equalizer 50 is not affected at all. Furthermore, after synchronization is established in the interior of the house 120, 22, there is no need to transmit high-level signals, so power consumption on the transmitting circuit side does not increase.

[Effects of the Invention] As explained above, according to the present invention, only the amplitude at the beginning of the transmission signal is made larger than the normal amplitude, and this signal is detected on the receiving side to establish frame synchronization.
Even if near-end crosstalk occurs, signals can be reliably exchanged without being affected by the near-end crosstalk.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a diagram of the configuration of a system to which the present invention is applied, Fig. 3 is a block diagram of the internal equipment, and Fig. 4 is a waveform diagram showing the operation of Fig. 3. , Fig. 5 is a configuration diagram of the in-home equipment, Fig. 6 is a diagram showing a time chart of the circuit shown in Fig. 5, Fig. 7 is a diagram of the system configuration of the conventional example, and Fig. 8 is the transmission/reception state of the conventional example. The explanatory diagram, FIG. 9, is a waveform diagram of a conventional reception operation. 1, 3, and 5, 20.22 is an in-home device, 24 is a subscriber line, 26.28 is an in-office device, 30 is a U/B conversion circuit, 36.38 is a selection circuit, and 40 is an in-house device. A variable gain equalization circuit, 42 a burst identification signal generation circuit, 44 a gate circuit, 46 a frame synchronization circuit, 48 a data processing circuit, 58 a comparator, and 60 a burst identification signal generation circuit.

Claims (1)

[Claims] (1) In a communication system in which a group of main communication stations and a group of sub-communication stations are connected via a two-wire transmission line, and signals are sent and received between each main communication station and each sub-communication station at regular intervals, Each main communication station increases the amplitude of the first signal of each transmitted signal and sends it out, and each sub-communication station synchronizes the frame of the received signal in response to the amplitude of the first signal of each received signal exceeding the burst detection level. A burst signal control method is characterized in that communication is started by establishing a