JPH03229547A - Frame offset measurement circuit - Google Patents

Abstract

PURPOSE:To confirm whether the specification of ANSI is satisfied or not by providing a fixed pattern generation part and a selector and measuring the offset of a reception frame and a transmission frame in a network terminal equipment-side U point by means of the reception frame and the transmission frame with fixed pattern. CONSTITUTION:A fixed pattern generation part 2 is provided, the fixed pattern composed of a binary code is generated and the selector 3 is provided. At the time of a test, the fixed pattern of the fixed pattern generation part 2 is transmitted instead of the output of scrambled transmission data from a scramble circuit 1. Thus, the detection of a frame pattern in the reception frame and the transmission frame is facilitated and the reception frame by the fixed pattern transmitted from a subscriber line terminal equipment is compared with the transmission frame by the fixed pattern returned from the network terminal equipment at the U point of the network terminal equipment. Thus, the offsets of the reception frame and the transmission frame at the U point of the network terminal equipment can be measured.

Description

[Detailed Description of the Invention] [Summary] Regarding a circuit that measures the offset between a received frame and a transmitted frame at a point U on the NT side in an l5DN basic interface, a 2BIQ code having a scrambled four-value amplitude at a point NT@U. The purpose is to measure the offset between the received frame and the transmitted frame, which consists of a signal that is scrambled through a scramble circuit, then inserted frame information in the frame insertion section, and then converted into a four-level code. In the subscriber line terminating device and the network terminating device of a system that performs communication via the subscriber line between the subscriber line terminating device and the network terminating device,
A fixed pattern creation section that creates a fixed pattern, and a selector that sends out the fixed pattern in place of the output of the scrambling circuit during testing are provided, and the received frame and the transmitted frame based on the fixed pattern are used to determine whether the fixed pattern at point U on the network terminating device side is It is constructed by measuring the offset between the received frame and the transmitted frame.

[Industrial application field]

The present invention is a network terminal device (NT; Network Terminal) in this I5DNI interface.
(or DSU; Digital 5ervi
This relates to a circuit that measures the offset between a received frame and a transmitted frame at point U on the ce unit) side.

In the 15DN, the subscriber line terminal equipment (L T
; Line Terminal) (or OCU
;0fficeChannel Unit), the scrambled binary signal is converted into a 2BIQ code consisting of a 4-value signal to reduce the signal speed and then transmitted via the subscriber line, and on the network side, the NT
is converted into a binary signal again via the terminal (TE; T
communication with the terminal equipment).

The same applies to transmission signals from the terminal side.

According to ANSI (American standard specifications), l5 in this case
Regulations are also provided for the NT network side in the DNi main interface. Among them, N T IJ U
The offset between the received frame and the transmitted frame at this point is determined to be 0.75 m5, taking into account the time required for microcomputer processing during the NT.

FIG. 5 shows an NT side received frame and an NT side transmitted frame. As shown in the figure, the NT side received frame and the NT side transmitted frame are ■.

It is assembled in units of 12m5 superframes consisting of eight 5ms basic frames, and the specified time difference, or offset, between the NT side received frame and the corresponding NT side transmitted frame is shown to be 0.75m5. .

So N T OI! It is desired to be able to measure this offset at the IU point, ie at the near end on the subscriber line on the NT side.

[Conventional technology]

Conventionally, the offset between a received frame consisting of a 2BIQ code with scrambled 4-level amplitude and a transmitted frame at the N T (jlJ U point) has not been measured at all.

[Problem to be solved by the invention]

The data on the subscriber line in rsDN is a 2BIQ code with 4-level amplitude as described above, and is scrambled.

Therefore, it is not possible to distinguish between frame information and scrambled data.

Therefore, it is difficult to simply compare the received frame and the transmitted frame and measure the offset by frame detection.

The present invention aims to solve the problems of the prior art as described above, and the present invention is aimed at solving the problems of the prior art. The purpose of this study is to measure whether the above-mentioned ANSI regulations are satisfied or not.

[Means for Solving the Problems] As shown in the principle structure of FIG. 1, the present invention scrambles transmission data through a scramble circuit 1, inserts frame information in a frame inserting section 4, and then converts it into a four-value code. A fixed pattern generator 2 and a selector 3 are used in a subscriber line termination device and a network termination device of a system in which communication is performed between a subscriber line termination device and a network termination device via a subscriber line using signals converted into The offset between the received frame and the transmitted frame at point U on the rope termination device side is measured using the received frame and transmitted frame according to a fixed pattern.

Here, the fixed pattern creation unit 2 creates a fixed pattern consisting of a binary code, and the selector 3 outputs the scrambled transmission data from the scramble circuit 1 during the test to the fixed pattern creation unit 2. It sends out a fixed pattern from

[Operation] In the communication system to which the present invention is directed, after transmitting data is scrambled via the scramble circuit 1, frame information is inserted in the frame inserting section 4, and further 4
The signal converted into a value code is sent from the network termination equipment via the subscriber line, and when the network termination equipment receives this signal, it returns a signal in the same format with a certain time difference (offset) so that it can communicate with each other. communicate.

In the subscriber line termination device and the network termination device of such a system, a fixed pattern creation section 2 is provided to create a fixed pattern consisting of binary codes, and a selector 3 is provided to generate a fixed pattern from the scramble circuit 1 during testing. In place of the output of the transmitted data, the fixed pattern of the fixed pattern creation section 2 is sent out.

Detection of such frame patterns in received frames and transmitted frames is easy, and therefore the U
By comparing the received frame with a fixed pattern sent from the subscriber line termination device at the point U and the transmission frame with the fixed pattern returned from the network termination device, the received frame and the transmitted frame at point U of the network termination device can be determined. It becomes possible to measure the offset of

〔Example〕

FIG. 2 shows the configuration of an embodiment of the present invention, and although the LT side is illustrated, the same applies to the NT side. In FIG. 2, 100 indicates LT, and LTlo
o consists of a scrambling section 10 and a code conversion section 20. In the scrambling unit 10, 1 is a scrambling circuit that scrambles transmission data, 2 is a fixed pattern creation circuit that creates fixed pattern transmission data, and 3 is a scrambled signal of the scramble circuit 1 and a fixed pattern of the fixed pattern creation circuit 2. 4 is a frame inserting unit that inserts frame information into the transmission signal. Further, in the code conversion section 20, 5
is a code conversion circuit that converts a binary code into a 2BIQ code consisting of a 4-value code.

In the normal mode, in the scrambler 10, the selector 3 selects the O side in response to a signal from the setting terminal. In this state, the transmission data consisting of a binary code is scrambled in the scramble circuit 1 and then outputted via the selector 3. Frame information is then inserted in the frame insertion section 4 and sent to the code conversion section 20.

In the code conversion unit 20, the transmission frame consisting of a binary code is converted into a 2B signal having a four-value amplitude in the code conversion circuit 5.
It is converted into an IQ code and output, and sent to an NT (not shown) via a subscriber line.

On the other hand, in the test mode, in the scrambler 10, the selector 3 selects the 1 side in response to a signal from the setting terminal. In this state, the fixed pattern transmission signal created by the fixed pattern creation section 2 is output via the selector 3. As the fixed pattern, for example, all ° "1's" can be used. Frame information is inserted into this fixed pattern in the frame insertion section 4 and sent to the code conversion section 20.

In the code conversion unit 20, as in the normal case, the transmission frame consisting of a binary code is converted into a 2BIQ code having a four-value amplitude in the code conversion circuit 5, and outputted, and the signal is transmitted via a subscriber line (not shown). Send to NT.

FIG. 3 shows the pulse pattern on the subscriber line, +3. +1. -1. -2BIQ with 4 values of 3
A frame pattern (S
ync Word), a data pattern consisting of 111 words is shown to be sent.

At this time, the frame pattern is the same in the normal mode and the test mode, but the data pattern changes depending on the transmitted data in the normal mode, but is always constant in the test mode.

FIG. 4 shows a frame offset observation system, which is shown to be composed of LTloo shown in FIG. 2, NT2O0, and an observation device 300 installed at point U of NT2O0.

The observation device 300 consists of an oscilloscope, a timer, etc., and is installed at the U point of NT2O0, that is, at the near end of the subscriber line.

By configuring the observation system in this way, LTloo
And in NT2O0, when selector 3 in the circuit of FIG. 2 is set to test mode, the frame pattern and data pattern are all fixed patterns, so when visually observed with an oscilloscope, for example, even if they are converted to a four-value code, Frame patterns can be easily distinguished from data patterns. Therefore, the frame offset can be measured by displaying the transmitted frame and the received frame simultaneously on an oscilloscope and measuring the time difference between portions of the frame pattern.

Another measurement method is to measure the frame offset from the time difference by using the transmit frame pattern and the receive frame pattern as triggers, start a timer depending on the receive frame pattern, and stop this timer depending on the transmit frame pattern. .

〔Effect of the invention〕

As explained above, according to the present invention, frame information is inserted after the transmission data is scrambled, and further 2BIQ
In a system in which LT and NT communicate with each other via a subscriber line using signals converted into codes,
Measure the offset between the received frame consisting of a 2BIQ code with scrambled 4-level amplitude and the transmitted frame at point U on the NT side, and easily check whether this satisfies the ANSI regulations. You will be able to do this.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic configuration of the present invention, Fig. 2 is a diagram showing the configuration of an embodiment of the present invention, Fig. 3 is a diagram showing the pulse pattern on the subscriber line, and Fig. 4 is a frame offset diagram. FIG. 5 is a diagram showing an NT side received frame and an NT side transmitted frame. 2 is a scrambling circuit, 2 is a fixed pattern creation section, 3 is a selector, and 4 is a frame insertion section.

Claims (1)

[Claims] Transmission data is scrambled through a scrambling circuit (1), frame information is inserted in a frame inserting section (4), and the signal is converted into a four-level code to be used between the subscriber line termination device and the network termination device. A fixed pattern creation unit (2) that creates a fixed pattern in a subscriber line termination device and a network termination device of a system that communicates via a subscriber line between them, and an output of the scrambling circuit (1) during testing. A selector (3) for transmitting the fixed pattern is provided in place of the fixed pattern, and the offset between the received frame and the transmitted frame at point U on the network terminal device side is measured based on the received frame and the transmitted frame according to the fixed pattern. frame offset measurement circuit.