JPH05227198A - Method and device for converting sts-1 signal to ds-3 signal and method for converting vt into ds-1 signal - Google Patents

Abstract

PURPOSE:To provide the device converting a STS-1 signal into a DS-3 signal without occurring excess alarm in response to a code without defining the post-stage terminal equipment. CONSTITUTION:An output circuit 19 outputs an idle code signal representing an idle code for DS-3 signal from an idle code generating device 18 to the post-stage terminal equipment when a signal label section detected from the SPE path overhead of an STS-1 signal 10 indicates 'unequipped' code. When the detected signal label section does not indicate the unequipped code, a demapping circuit 17 outputs an information section extracted from the SPE payload to the post-stage terminal equipment as a DS-3 signal 11. In converting the VT into DS-1 signal, the idle code defined for DS-1 signal is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an STS-1 signal (sync
The present invention relates to a method and apparatus for processing a synchronous transport signal level 1: a synchronous transport signal level 1) into a DS-3 signal (digital signal level 3: digital signal level 3). The present invention also converts a VT (virtual tributary) into a DS-1 signal (digital signal level).
el 1: relates to a method of processing a digital signal level 1).

[0002]

2. Description of the Related Art STS-1 signals and VT are specified as standards (for example, American National Standard).
American National Standard f published by s Institute, Inc
or Telecommunications-Digital Hierarchy-Optical In
terface Rates and Specifications (SONET), T1X1.5 / 90
-025R3 / T1X1 / 90-055R2, Draft-November 1990, pages 9
-23 Reference: Hereinafter referred to as the literature).

The STS-1 signal corresponds to 14 and 1 of the above document.
51.840 Mb as specified on page 5, paragraph 5
Has a bit rate of it / s. The STS-1 signal has an STS synchronous payload envelope (S) having first to Mth subframes (M represents a plurality of natural numbers).
TS-1 SPE). M is effectively equal to 9. Each of the first to Mth subframes has an STS path overhead (STS-1 POH) and a payload having an information section.

As specified on page 21 of the above-mentioned document, whether the STS synchronous payload envelope is unequipped is a predetermined one of the STS path overheads of the first to Mth subframes. It is assigned as an STS path signal label portion indicating whether or not. The STS path signal label part indicates an unequipped code in which all bits are 0 when the STS synchronous payload envelope is unequipped. In practice, the STS path overhead of the third subframe is assigned as the STS path signal label part.

The information portion of the payload of the first to Mth subframes is D when the STS synchronous payload envelope is not unequipped.
Used to carry S-3 signals. The STS-1 signal is actually used when the STS synchronous payload envelope is not unequipped. When the STS Synchronous Payload Envelope is Unequipped, the STS-1 signal is unused and
Therefore, it is called an unused STS-1 signal. The DS-3 signal has a bit rate of 44.736 Mbit / s. Anyway, D
The S-3 signal is carried by the STS synchronous payload envelope.

The DS-1 signal is lower than the DS-3 signal
Since it has a bit rate of 1.544 Mbit / s, the DS-1 signal can be converted into S, as specified in the left column on page 15 of the above document.
It is transmitted by a VT of size x defined in the TS synchronous payload envelope. For example, a VT of size 1.5 is described on page 16, paragraph 8.
As specified in 1.3, it has a bit rate of 1.728 Mbit / s.

A VT of size x has a VT Synchronous Payload Envelope (VT SPE). The VT synchronous payload envelope has a VT path overhead (VT POH) and a payload having an information part. Some of the VT path overhead is
It is assigned as a VT path signal label portion indicating whether the VT synchronous payload envelope is unequipped. The VT path signal label part indicates an unequipped code in which all bits are 0 when the VT synchronous payload envelope is unequipped. VT Synchronous
The payload information portion of the payload envelope is used to carry the DS-1 signal when the VT synchronous payload envelope is not unequipped. VT synchronous payload
A VT of size x is actually used when the envelope is not unequipped. If the VT synchronous payload envelope is unequipped, its V
T is unused and is therefore called the unused VT.

[0008]

As described above, an unused code should be set in the STS path signal label portion for an unused STS-1 signal, and an unused size. For the VT of x, it is specified that the unequipped code should be set in the VT path signal label part. However, the STS synchronous signal for the unused STS-1 signal
There is no provision for the information part of the payload of the first to Mth subframes of the payload envelope, and the information part of the payload of the VT synchronous payload envelope for an unused VT of size x. Since it is not present, for example, an unspecified code consisting of all bits of 0 is transmitted by an unused STS-1 signal information section or an unused VT information section of size x. It cannot be avoided.

Unused STS in conventional processing equipment
When the -1 signal or an unused VT of size x is processed, the conventional processing device outputs the above-mentioned unspecified code instead of the DS-3 signal or the DS-1 signal.
As a result, the terminal device at the next stage will generate an unnecessary alarm in response to the unspecified code.

Therefore, an object of the present invention is to prevent the occurrence of unnecessary alarms in the terminal equipment at the next stage.
It is to provide a method of processing a -1 signal into a DS-3 signal.

Another object of the present invention is to prevent the occurrence of unnecessary alarms in the terminal equipment at the next stage.
It is to provide a device for processing an S-1 signal into a DS-3 signal.

Another object of the present invention is to prevent the occurrence of unnecessary alarms in the terminal equipment at the next stage by changing VT to DS.
-1 signal.

Other objects of the present invention will become clear as the description proceeds.

[0014]

According to the present invention, the STS
-1 signal to a DS-3 signal, wherein the STS-1 signal comprises an STS synchronous payload envelope having first to Mth subframes (M represents a plurality of natural numbers). Having the first to the Mth
Each of the subframes of STS path overhead,
And a payload having an information part,
A predetermined one of the STS path overheads of the first to Mth subframes is assigned as an STS path signal label portion indicating whether the STS synchronous payload envelope is unequipped, and In the method, the information part of the payload of the first to Mth subframes is used to transmit the DS-3 signal when the STS synchronous payload envelope is not unequipped. -1 signal of the STS
A detecting step of detecting the STS path signal label part as a detected STS path signal label part from the STS path overhead of the first to Mth subframes of the synchronous payload envelope; The STS path signal label section determines whether or not the STS synchronous payload envelope indicates unequipped; and from the STS-1 signal, the STS synchronous payload envelope An extraction step of continuously extracting the information part of the payload of the first to Mth subframes as a series of extracted information parts; defined for the DS-3 signal Idle representing the idol code And a step of generating a read signal; wherein the determination that the detected STS path signal label portion indicates that the STS synchronous payload envelope is not unequipped is made in the determination step. , Outputting the series of extracted information parts as the DS-3 signal, and the detected STS path signal label part indicating that the STS synchronous payload envelope is unequipped. A method for processing an STS-1 signal into a DS-3 signal, characterized in that it comprises an output step of outputting the idle code signal when the determination is made in the determination step.

Further in accordance with the present invention, the STS-1 signal is D
An apparatus for processing an S-3 signal, wherein the STS-1 signal has an STS synchronous payload envelope having first to Mth (M represents a plurality of natural numbers) subframes, Each of the first to Mth subframes has an STS path overhead and a payload having an information part, and the predetermined one of the STS path overheads of the first to Mth subframes is STS indicating whether the STS synchronous payload envelope is unequipped
The information section, which is assigned as a path signal label section, of the payload of the first to Mth subframes is the STS synchronous
In the apparatus used to transmit the DS-3 signal when the payload envelope is not unequipped, the STS-1 signal is received and the first to Mth subs of the STS synchronous payload envelope are received. From the STS path overhead of the frame, the STS path signal label portion is detected S
Detection means for detecting the TS path signal label portion;
Determining means connected to the detecting means and determining whether or not the detected STS path signal label part indicates that the STS synchronous payload envelope is unequipped; Receiving the information part of the payload of the first to Mth subframes of the STS synchronous payload envelope from the STS-1 signal as a series of extracted information parts. Extracting means for extracting into
Generating means for generating an idle code signal representing an idle code defined for the signal; and the detected STS path signal label portion connected to the judging means, the extracting means and the generating means, When it is determined in the determination means that the synchronous payload envelope is not unequipped, the series of extracted information units is output as the DS-3 signal, and the detected information section is detected. And an output means for outputting the idle code signal when the determination means determines that the STS path signal label portion indicates that the STS synchronous payload envelope is unequipped; Processing the STS-1 signal into a DS-3 signal. The device is obtained.

Further, according to the present invention, there is provided a method of processing a VT into a DS-1 signal, wherein the VT has a VT synchronous payload envelope, and the VT synchronous payload envelope comprises: A VT path overhead and a payload having an information part are provided, and a part of the VT path overhead is allocated as a VT path signal label part indicating whether or not the VT synchronous payload envelope is unequipped. The information part of the payload of the VT synchronous payload envelope is the DS- when the VT synchronous payload envelope is not unequipped.
Detecting the VT path signal label part as a detected VT path signal label part from the VT path overhead of the VT synchronous payload envelope of the VT. A detecting step of: detecting the detected VT
A determination step of determining whether or not the path signal label portion indicates that the VT synchronous payload envelope is unequipped; and from the VT, the input of the payload of the VT synchronous payload envelope. An extraction step of extracting the formation part as an extracted information part; a generation step of generating an idle code signal representing an idle code defined for the DS-1 signal; the detected VT path signal It is determined that the label part indicates that the VT synchronous payload envelope is not unequipped,
When the determination step is performed, the extracted information portion is output as the DS-1 signal, and the detected VT path signal label portion is
A step of outputting the idle code signal when the determination that the VT synchronous payload envelope indicates unequipped is performed in the determination step; A method of processing a VT into a DS-1 signal is obtained.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

First, referring to FIG. 1, a processing apparatus for carrying out the method according to the first embodiment of the present invention will be described. This processing device converts an STS-1 signal 10 into a DS-3 signal 11
How to handle it.

This processing device uses SONET (synchronou
s optical network) included in SONET terminal equipment (not shown) that receives signals. SON
The ET signal is typically an OC-N signal (optical carr).
ier level N signal: optical carrier level N signal). Here, N is a plurality of integers. The SONET terminal equipment includes a receiver having a combination of an optoelectric converter and a demultiplexer for converting and separating OC-N signals into first to Nth STS-1 signals. This processor is
One of the first to Nth STS-1 signals is received as the STS-1 signal 10.

Referring to FIG. 2, the STS-1 signal has first to ninth rows, each row consisting of first to 90th bytes (octets) or columns. Each byte consists of 8 bits. The first to third bytes of the first to ninth rows are
It acts as a known transmission overhead. 1st to 9th
The remaining bytes (4th to 90th bytes) of the row are ST
S Synchronous Payload Envelope (STS-1 SP
E) acts as. The STS Synchronous Payload Envelope (STS-1 SPE) has S
It can start anywhere in the TS envelope capacity. Transmission overhead is a payload pointer (not shown) that points to the beginning byte of the STS Synchronous Payload Envelope (STS-1 SPE).
Have.

The STS synchronous payload envelope (STS-1 SPE) has first to Mth subframes (M represents a plurality of natural numbers) in succession. Illustrated S
TS Synchronous Payload Envelope (STS-1 S
PE) has first to ninth subframes. Each of the first to ninth subframes has an STS path overhead (STS-1 POH) and a payload.

The subframe will be described in detail with reference to FIG. Each of the first to ninth subframes is
STS Synchronous Payload Envelope (STS-1
SPE) has the STS path overhead (STS-1 POH) in the first column (ie, the first byte) and the payload in the second to 87th columns (ie, the second to 87th bytes). Have. The payload of each of the first to ninth subframes has an information part indicated by 5I, 25 × 8I, 8I. Here, I indicates an information bit. In FIG. 3, R, C, S, and O represent fixed stuff bits, stuff control bits, stuff opportunity bits, and overhead communications channel bits. These bits R, C, S and O are known. The STS path overhead (STS-1 POH) of the third subframe is allocated as the STS path signal label portion indicated by L. In the STS path signal label portion L, the STS synchronous payload envelope (STS-1 SPE) is unequipped (Unequip).
ped) or not. The STS path signal label part L is an STS synchronous payload envelope.
When (STS-1 SPE) is unequipped, it shows an unequipped code in which all bits are 0.

The information portion of the payload of the first to ninth subframes is used to transmit the DS-3 signal when the STS synchronous payload envelope (STS-1 SPE) is not unequipped. S
TS Synchronous Payload Envelope (STS-1 S
The STS-1 signal is actually used when PE) is not unequipped. When the STS Synchronous Payload Envelope (STS-1 SPE) is Unequipped,
The STS-1 signal is unused and is therefore referred to as the unused STS-1 signal as described above. Anyways,
The DS-3 signal is transmitted by the STS Synchronous Payload Envelope (STS-1 SPE).

Referring to FIG. 1, FIG. 2 and FIG. 3, the present processing apparatus has a pointer detection unit 1 that receives an STS-1 signal 10.
Have two. The pointer detection unit 12 determines from the transmission overhead that the STS synchronous payload envelope is
Find the payload pointer to the position of the beginning byte of (STS-1 SPE). The pointer detection unit 12 outputs a path overhead extraction timing pulse 13 and a payload extraction timing pulse 14. The path overhead (POH) detection unit 15 receives the STS-1 signal 10 and the path overhead extraction timing pulse 13, selects the third path overhead extraction timing pulse of the path overhead extraction timing pulse 13, and selects the STS synchronous payload. STS path overhead of the first to ninth subframes of the envelope (STS-1 SPE)
From (STS-1 POH), change the STS path signal label part L to
It is detected as the detected STS path signal label portion.

In this way, the path overhead detection unit 15
Operates as a detection circuit in cooperation with the pointer detection unit 12. This detection circuit receives the STS-1 signal 10,
STS Synchronous Payload Envelope (STS-1
The STS path signal label portion L is detected as the detected STS path signal label portion from the STS path overhead (STS-1 POH) of the first to ninth subframes of SPE).

The judging circuit 16 is connected to the path overhead detecting section 15 of the detecting circuit, and detects that the detected STS path signal label section is an unequipped STS synchronous payload envelope (STS-1 SPE). It is determined whether or not it is shown.

The demapping circuit 17 receives the STS-1 signal 10 and refers to the payload extraction timing pulse 14 to extract the first STS synchronous payload envelope (STS-1 SPE) from the STS-1 signal 10. To the ninth to ninth sub-frame payload information parts are continuously extracted, and the first to ninth sub-frame payload information parts are temporarily stored as a series of extracted information parts. ..

As described above, the demapping circuit 17 cooperates with the pointer detecting section 12 to act as an extracting circuit. The extraction circuit receives the STS-1 signal 10 and receives the ST
From the S-1 signal 10, the information parts of the payloads of the first to ninth subframes of the STS synchronous payload envelope (STS-1 SPE) are consecutively extracted as a series of extracted information parts. Extract.

The idle code generator 18 generates an idle code signal representing an idle code defined for the DS-3 signal. The idle code defined for this DS-3 signal is a known series of bits 1100.
・ ・ It consists of.

The output circuit 19 is connected to the decision circuit 16, the demapping circuit 17, and the idle code generator 18. When the determination circuit 16 determines that the detected STS path signal label portion indicates that the STS synchronous payload envelope (STS-1 SPE) is not unequipped, the output circuit 19 outputs Select a series of extracted information parts, and select a series of extracted information parts by DS-
3 signal 11 is output. The output circuit 19 determines that the detected STS path signal label portion indicates that the STS synchronous payload envelope (STS-1 SPE) is unequipped, and the determination circuit 16
, The idle code signal is selected and output.

In this processor, an unused STS-
When one signal is processed, this processing device outputs an idle code signal instead of the DS-3 signal 11 and transmits this idle code signal to the terminal device at the next stage. This idle code signal represents an idle code specified for the DS-3 signal, and is not the above-mentioned code that is not specified. Therefore, this processing device uses a code that does not specify the next terminal device. It is possible to prevent a problem that an unnecessary alarm is generated in response.

Next, referring to FIG. 4, a processing apparatus for carrying out the method according to the second embodiment of the present invention will be described. This processor implements the method of processing a VT 20 of size 1.5 into a DS-1 signal 21. As mentioned above, DS
The -1 signal is transmitted by the VT 20 having a size of 1.5 defined in the STS synchronous payload envelope (STS-1 SPE) of the STS-1 signal.

Referring to FIG. 5, a VT of size 1.5 is
VT Synchronous Payload Envelope (VT SPE)
Have. The VT Synchronous Payload Envelope (VT SPE) has a VT path overhead (V5) and a payload having an information part. V
The T path overhead (V5) is located in the first byte of the VT Synchronous Payload Envelope (VT SPE). VT Synchronous Payload Envelope (V
The remaining bytes of T SPE) are for the payload.
A part (specifically, the fifth to seventh bits) of the VT path overhead (V5) is a VT path signal label part indicating whether or not the VT synchronous payload envelope (VT SPE) is unequipped. Is assigned as. The VT path signal label part indicates an unequipped code in which all bits are 0 when the VT synchronous payload envelope (VTSPE) is unequipped. VT synchronous payload
The information portion of the envelope (VT SPE) payload is used to carry the DS-1 signal when the VT synchronous payload envelope (VT SPE) is not unequipped. A VT of size 1.5 is actually used when the VT Synchronous Payload Envelope (VT SPE) is not unequipped. When the VT Synchronous Payload Envelope (VT SPE) is unequipped, the VT is not in use,
Therefore, it is called an unused VT as described above.

Referring to FIGS. 4 and 5, the present processing device is
Path overhead (P of receiving size 1.5 VT20)
OH) detection circuit 25. The path overhead detection circuit 25 sets the VT path signal label portion as the detected VT path signal label portion from the VT path overhead (V5) of the VT synchronous payload envelope (VT SPE) of the VT 20 of size 1.5. To detect.

The decision circuit 26 is connected to the path overhead detection circuit 25, and the detected VT path signal label portion is the VT synchronous payload envelope (V
T SPE) indicates that it is unequipped.

The extraction circuit 27 is a VT 20 of size 1.5.
In response, the information part of the payload of the VT synchronous payload envelope (VT SPE) is extracted from the VT 20 of size 1.5 as the extracted information part.

The idle code generator 28 generates an idle code signal representing an idle code defined for the DS-1 signal. The idle code defined for the DS-1 signal is publicly known, for example, all bits are 1s.

The output circuit 29 is connected to the judging circuit 26, the extracting circuit 27, and the idle code generator 28. In the output circuit 29, the detected VT path signal label portion is the VT synchronous payload envelope.
When the determination circuit 26 determines that (VT SPE) does not indicate unequipped, the extracted information unit is output as the DS-1 signal 21. When the determination circuit 26 determines that the detected VT path signal label portion indicates that the VT synchronous payload envelope (VT SPE) is unequipped, the output circuit 29 outputs:
Output an idle code signal.

When an unused VT having a size of 1.5 is processed in this processing device, the processing device operates as DS-
Instead of the 1 signal 21, an idle code signal is output and this idle code signal is transmitted to the terminal device at the next stage. This idle code signal represents an idle code specified for the DS-1 signal, and is not the above-mentioned code that is not specified. It is possible to prevent a problem that an unnecessary alarm is generated in response.

[0040]

As described above, according to the present invention,
It is possible to obtain a method of processing an STS-1 signal into a DS-3 signal, which can prevent an unnecessary alarm from being generated in the terminal device at the next stage.

Further, according to the present invention, it is possible to prevent the generation of an unnecessary alarm in the terminal equipment of the next stage, STS-1.
An apparatus can be obtained that processes the signal into a DS-3 signal.

Further, according to the present invention, it is possible to prevent the occurrence of unnecessary alarms in the terminal equipment at the next stage by setting VT to D.
A method of processing the S-1 signal can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a processing device for performing a method according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an STS-1 signal.

3 is an STS synchronous STS-1 signal of FIG.
It is a figure for demonstrating the sub-frame of a payload envelope (STS-1 SPE).

FIG. 4 is a block diagram of a processing device for performing the method according to the second embodiment of the present invention.

FIG. 5 is a diagram for explaining VT.

[Explanation of symbols]

 10 STS-1 signal 11 DS-3 signal 12 pointer detection unit 13 path overhead extraction timing pulse 14 payload extraction timing pulse 15 path overhead (POH) detection unit 16 determination circuit 17 demapping circuit 18 idle code generator 19 output circuit 20 size 1.5 VT 21 DS-1 signal 25 Path overhead (POH) detection circuit 26 Judgment circuit 27 Extraction circuit 28 Idle code generator 29 Output circuit

Claims (3)

[Claims] 1. A method of processing an STS-1 signal into a DS-3 signal, wherein the STS-1 signal comprises first to M-th signals.
S with subframes (M represents multiple natural numbers)
It has a TS synchronous payload envelope,
Each of the first to Mth subframes has an STS
A path overhead and a payload having an information part, and the predetermined one of the STS path overheads of the first to Mth subframes is the S
The TS synchronous payload envelope is assigned as an STS path signal label section indicating whether or not it is unequipped, and the information section of the payload of the first to Mth subframes is assigned to the STS sync signal. The method used for transmitting the DS-3 signal when the eggplant payload envelope is not unequipped, wherein the first to the Mth sub-items of the STS synchronous payload envelope of the STS-1 signal are included. A detection step of detecting the STS path signal label portion as a detected STS path signal label portion from the STS path overhead of a frame; and the detected STS path signal label portion being the STS synchronous payload envelope. Determining whether the loop indicates unequipped;
The information part of the payload of the first to Mth subframes of the STS synchronous payload envelope is continuously extracted as a series of extracted information parts from the STS-1 signal. A generating step of generating an idle code signal representing an idle code defined for the DS-3 signal; the detected S
When the determination that the TS path signal label portion indicates that the STS synchronous payload envelope is not unequipped is made in the determination step, the series of extracted information portions is set to the DS- When it is determined in the determination step that the detected STS path signal label portion indicates that the STS synchronous payload envelope is unequipped, the idle signal is output. An output step of outputting a code signal;
A method of processing a -1 signal into a DS-3 signal. 2. An apparatus for processing an STS-1 signal into a DS-3 signal, wherein the STS-1 signal includes first to Mth signals.
S with subframes (M represents multiple natural numbers)
It has a TS synchronous payload envelope,
Each of the first to Mth subframes has an STS
A path overhead and a payload having an information part, and the predetermined one of the STS path overheads of the first to Mth subframes is the S
The TS synchronous payload envelope is assigned as an STS path signal label section indicating whether or not it is unequipped, and the information section of the payload of the first to Mth subframes is assigned to the STS sync signal. In the apparatus used to transmit the DS-3 signal when the eggplant payload envelope is not unequipped, the apparatus receives the STS-1 signal and receives the STS synchronous signal.
From the STS path overhead of the first to Mth subframes of the payload envelope, the S
A detection means for detecting the TS path signal label portion as a detected STS path signal label portion; and a detection means connected to the detection means, wherein the detected STS path signal label portion is unequipped with the STS synchronous payload envelope. Determining means for determining whether or not the STS-1 signal is received, and the first to Mth subframes of the STS synchronous payload envelope are received from the STS-1 signal. The information part of the payload of as a series of extracted information parts,
Extracting means for continuously extracting; generating means for generating an idle code signal representing an idle code defined for the DS-3 signal; connected to the determining means, the extracting means and the generating means, When it is determined in the determination means that the detected STS path signal label portion indicates that the STS synchronous payload envelope is not unequipped, the series of extracted information portions is extracted. Is output as the DS-3 signal, and the determination unit determines that the detected STS path signal label portion indicates that the STS synchronous payload envelope is unequipped. Sometimes output means for outputting the idle code signal;
An apparatus for processing an STS-1 signal into a DS-3 signal, comprising: 3. A method of processing a VT into a DS-1 signal, wherein the VT has a VT synchronous payload envelope, the VT synchronous payload envelope including a VT path overhead and an VT path overhead. A payload having a formation part, said VT
A part of the path overhead is allocated as a VT path signal label portion indicating whether or not the VT synchronous payload envelope is unequipped, and the information of the payload of the VT synchronous payload envelope is assigned. The section is used for transmitting the DS-1 signal when the VT synchronous payload envelope is not unequipped, wherein the VT path overhead of the VT synchronous payload envelope of the VT comprises: A detecting step of detecting the VT path signal label portion as a detected VT path signal label portion;
A determination step of determining whether or not the T-path signal label portion indicates that the VT synchronous payload envelope is unequipped;
From the information part of the payload of the VT synchronous payload envelope,
An extraction step of extracting as the extracted information section; a generating step of generating an idle code signal representing an idle code defined for the DS-1 signal; and the detected VT path signal label section, The determination that the VT synchronous payload envelope is not unequipped,
When the determination step is performed, the extracted information portion is output as the DS-1 signal, and the detected VT path signal label portion is
A step of outputting the idle code signal when the determination that the VT synchronous payload envelope indicates unequipped is performed in the determination step; A method of processing a VT into a DS-1 signal.