JPH04360386A - Video signal multiplexer system - Google Patents

Abstract

PURPOSE:To attain relay transmission of alarm information as information in the unit of a channel by fetching alarm information representing a line fault to a pay load when 2-channels of a TV signal of the NTSC system and information on such as an audio and low speed data are multiplexed onto the pay load being a C4 data of the STM-1 frame and sent. CONSTITUTION:A multiplexer section 1 multiplexes an NTSC signal by 2 channels so as to be mapped onto an STM-1 frame C4 data and an SDH format processing section 2 maps alarm information corresponding to the channel and a data outputted from the multiplexer section 1 onto the C4 data. Moreover, an SDH addition section 3 adding an overhead to a tip of the C4 data outputted from the SDH format processing section 2 is provided. Thus, even when the data is branched, inserted, relayed and switched in the unit of one channel, alarm information is accurately transferred.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal multiplexing method in a multi-channel video transmission apparatus using a synchronous digital hierarchy.

[0002] In recent years, a synchronous digital hierarchy (hereinafter referred to as SDH) has been defined by CCITT as a basic network interface for network construction. Along with this, video and audio transmission also needs to be compatible with the SDH interface of the synchronous digital hierarchy.

0003

2. Description of the Related Art In the field of surveillance television and CATV, an NTSC signal, which is a set of a video signal with a bandwidth of 4.2 MHz and an audio signal with a bandwidth of 20 KHz, is handled. This NT
The SC signal is processed and formed as follows.

[0004] The 4.2 MHz video signal is first sampled to create an 8.95 Mbps digital signal, and then converted into an 8-bit digital signal.
Forms a digital video signal with a communication speed of 1.84 MHz.

On the other hand, for the audio signal of 20 KHz, a signal obtained by adding other data to the audio signal is sampled to form a digital stereo signal with a communication speed of 2.88 Mbps. This digitized 71.84
An NTSC signal with a communication speed of 74.48 Mbps is formed based on two signals of MHz and 2.88 MHz, and the
The TSC signal is being transmitted over the network.

[0006] SDH is defined by CCITT as a network interface that is the basis of this network construction, and FIG.
1) Shows the frame structure of the interface.

As shown in FIG. 6, the STM-1 frame (
155.52 Mbps) has a configuration of 270 columns (1 column = 1 byte = 8 bits) x 9 rows, with 9 columns of section overhead (SOH) and 1 column of path overhead (P
OH) and 260 columns of payloads (data storage locations). Note that this payload (hereinafter referred to as C4
(referred to as data) is 260 columns, 149.76 Mbps
is given by the communication speed.

[0008] The overhead (OH), which is composed of the SOH and POH described above, is an information transmission unit for monitoring and controlling the SDH system, and as shown in FIG. 7, it detects bit errors (parity errors) between sections. Information B1, bit error (parity error) detection information between line layers B2, parity calculation information for all bits of VC-4 of the previous frame B3
, frame synchronization signals A1 and A2, and alarm information F1 indicating line abnormality are mapped. These pieces of OH information are detected by the receiving device and used for frame synchronization detection and parity checking. Further, the alarm information F1 is relayed to the lower station as F1 byte information at the relay station.

[0009]

By the way, when multiplexing and transmitting multi-channel information in SDH, it is necessary to transfer alarm information in multiple directions. That is, if data is branched, inserted, relayed, and switched on a channel-by-channel basis, alarm information is required for each channel. However, in OH, it has been impossible to map and transmit multiple pieces of alarm information. The present invention was made in consideration of the above circumstances, and it is possible to convert two channels of NTSC TV signals and accompanying information such as audio and low-speed data into STM.
- When efficiently multiplexing and transmitting the payload, which is one frame of C4 data, by incorporating alarm information indicating line abnormality into the payload, it is possible to relay the alarm information as information for each channel. The purpose of the present invention is to provide a video signal multiplexing method for

0010

[Means for Solving the Problems] A video signal multiplexing system according to the present invention maps two channels of NTSC signals, which are two channels of video signals and at least two channels of audio signals, to C4 data of an STM-1 frame. SDH formatting that maps the data output by the multiplexer 1 and the alarm information added corresponding to each channel to C4 data of the STM-1 frame. section 2 and an SDH adding section 3 that adds overhead to the leading end of the C4 data output from the SDH formatting section 2, and when using a synchronous digital hierarchy, the multi-channel video signal and alarm information for each channel can be combined. It is characterized by enabling transmission.

[0011]

[Operation] The multiplexer 1 multiplexes the NTSC signals for two channels so that they are mapped onto the C4 data of the STM-1 frame, and the SDH formatter 2 multiplexes the C4 data with alarm information corresponding to each channel. The data output from the conversion unit 1 is mapped. Therefore, even when branching, inserting, relaying, and switching data on a channel-by-channel basis, it is possible to accurately transfer alarm information.

0012

EXAMPLES Examples of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to the following examples.

FIGS. 1 and 2 are system configuration diagrams of an embodiment of the present invention, with FIG. 1 showing a transmitting section 100 and FIG. 2 showing a receiving section 20.
0, connecting points J1 and J3 and connecting points J2 and J
4 are connected respectively. FIG. 3 is a feature of the embodiment,
2 is a block diagram showing the configuration of a 2-channel multiplexer 1, an SDH formatter 2, and an SDH adder 3. FIG. In the system of this embodiment, eight channels of NTSC signals can be multiplexed and mapped onto an STM-4 frame. In FIGS. 1 and 2, 2-channel video signal #1 (video input #1, video output #1), video signal #2 (video input #2, video output #2), and 2-channel audio signal #1 (audio input #1, audio output #1) and audio signal #2 (audio input #2, audio output #2) are shown in the figure, and since the other signals are the same, illustration and explanation will be omitted.

In FIG. 1, 4, 5, 6, and 7 are A/D converters, which convert video signals #1, #2 and audio signals #1, #2.
2 is analog-to-digital converted and output to the channel switching section 8. The channel switching unit 8 includes each A/D converter 4,
5, 6, 7 and video signals #3, 4, 5, 6, not shown,
A for 7, 8 and audio signals #3, 4, 5, 6, 7, 8
/Digital signal from D converter or receiver 2
It branches, inserts, relays, and switches the digital signals sent from 00 on a channel-by-channel basis.

A unit consisting of a two-channel multiplexing section 1, an SDH formatting section 2, and an SDH adding section 3 is connected to the output end of each channel of the channel switching section 8, respectively. Details of this unit are illustrated in FIG. The 2-channel multiplexer 1 includes a #1 speed converter 1a, a #2 speed converter 1b, a #1 memory section 1c, and a #2 memory section 1d. The SDH formatting section 2 includes a #3 speed converting section 2a, a #3 memory section 2b, and a MUX section 2c. The SDH addition unit 3 may have the same configuration as the conventional one. An SDH multiplexing section 9 is connected to the SDH adding section 3. Furthermore, an electrical/optical converter 10 is connected to the SDH multiplexer 9 . The electrical/optical converter 10 is connected to an optical transmission line.

Next, in FIG. 2, the receiving section 200 includes an optical/electrical converter 11 that converts an optical signal from an optical transmission line into an electrical signal, and an SDH separation/reception synchronization section that detects a synchronization loss (REC) alarm. 12 and parity error (B1, B2, B
3) SDH termination section 13 that detects an alarm, SDH format separation section 14 that separates C4 data and outputs 2-channel multiplexed data, and SDH format separation section 14
A D/A converter consisting of a 2-channel separator 15 that separates the 2-channel multiplexed data outputted from the 2-channel multiplexed data into data for each channel, a channel switching unit 16, and D/A converters of the same number as the number of channels of the video signal and the audio signal. It is composed of an A conversion section 17.

The operation of the embodiment will be explained. Note that in the following explanation, the operation of creating an STM-1 frame will be mainly explained, and the STM-4 frame will be explained using the STM-4 frame.
Since it is an integral multiple of one frame, the explanation will be omitted. In the transmitter 100, the video signals #1 and #2 are sampled at 9 Mbps and 8 bits by A/D converters 4 and 5, respectively, to become PCM-encoded digital video data V1 and V2 of 72 Mbps. Similarly, audio signals #1 and #2 are converted to P by A/D converters 6 and 7.
The data is CM-encoded into digital audio data M1 and M2 of 2.88 Mbps, respectively. These data are
The channel switching unit 8 inserts other data or branches the data in units of channels, and inputs the resulting data to the two-channel multiplexing unit 1. Alarm information is input to the two-channel multiplexer 1 via the channel switching section 8 as in the conventional case.

In the 2-channel multiplexer 1, first, the input digital video data V1, V2 is converted into a first clock CLK1 of 8.95 MHz in the #1 speed converter 1a.
The signal is inputted at the timing of 19.44 MHz, P/S converted by the second clock CLK2 of 19.44 MHz, and converted into data of one channel. Similarly, the digital audio signals M1 and M2 are input to the second speed converter 1b at the timing of the third clock CLK3 of 2.88 MHz, and the second clock CLK
2, the data is P/S converted and becomes one channel data. 1
The channelized digital video data V1 and V2 are
The digital audio data M1 and M2 stored in the #1 memory unit 1c at the timing of the video write clock WCLK1 and made into one channel are the audio write clock WCLK2.
It is stored in the #2 memory section 1d at the timing of . The respective data stored in the #1 memory section 1c and the #2 memory section 1d are stored in the respective video read clocks RCLK1 so as to be mapped to the frame configurations shown in FIGS. 4 and 5.
, and is read out at the timing of the audio reading clock RCLK2 and output to the MUX section 2c of the SDH formatting section 2.

Next, the SDH formatting section 2 converts the alarm information for each channel into C4 data, that is, STM-1
The video alarm information AI, AII of each video signal and the audio alarm information AIII, AIV of each audio signal are input at the timing of the third clock CLK3, and at the timing of the second clock CLK2, in order to be mapped to the empty bytes of the payload of the frame. #3 memory section 2 after P/S conversion
b at the timing of the alarm write clock WCLK3. The stored alarm information is the alarm readout clock RC.
It is read out at the timing of LK3 and output to the MUX section 2c. The MUX unit 2c multiplexes the input digital video data V1, V2, digital audio data M1, M2, and alarm information AI, AII, AIII, and AIV, and performs mapping so that the frame configurations shown in FIGS. 4 and 5 are obtained. .

[0020] Then, the SDH adding unit 3 adds overhead to the C4 data created by the MUX unit 2c, as in the conventional case, and creates C4 data (payload) of 260 bytes (columns) x 9 rows and 10 bytes (columns) x An STM-1 frame consisting of 9 lines of overhead is created. 4 and 5 are continuous along the line segment XX, and the mapping of the portions indicated by asterisks has the same configuration. In addition, I1,
I2 is the ID number of the warning corresponding to the video warning, and I3 and I4 are the ID numbers corresponding to the audio warning information.

[0021] The created STM-1 frame is SDH
The signals are multiplexed by the multiplexer 9 and output to the optical transmission line via the electrical/optical converter 10 as an STM-4 frame with a transmission rate of 622 Mbps. In the above embodiment, the video signal and the audio signal were mapped to the STM-1 frame, but the audio signal with a bandwidth of, for example, 3.4 kHz, contact information, and even low-speed data may be mapped to the STM-1 frame. , may be multiplexed and mapped onto the audio signal.

[0022]

As is clear from the above description, according to the present invention, a plurality of pieces of alarm information can be transmitted by effectively utilizing the free bytes of C4 data. Therefore, it is possible to switch and relay alarm information in different directions for each channel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a transmitter of a system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a receiving section of a system according to an embodiment of the present invention.

FIG. 3: Two-channel multiplexer, SDH, according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a formatting section and an SDH adding section.

FIG. 4 is a configuration explanatory diagram showing a frame configuration of C4 data (payload) in the embodiment.

FIG. 5 is a configuration explanatory diagram showing a frame configuration of C4 data (payload) in the embodiment.

FIG. 6 is a configuration explanatory diagram showing a frame structure of a 155.52 Mbps (STM-1) interface.

FIG. 7 is a configuration explanatory diagram showing conventional overhead mapping.

[Explanation of symbols]

1 2 channel multiplexer 2 SDH formatting section 3 SDH addition section

Claims (1)

[Claims] [Claim 1] A two-channel video signal and at least two
NTSC for two channels consisting of the audio signal of the channel
A multiplexing unit (1) that multiplexes signals so as to map them to C4 data of an STM-1 frame, data output by the multiplexing unit (1), and alarm information added corresponding to each of the channels. and C of the STM-1 frame
SDH formatting unit (2
) and the C output from the SDH formatting section (2).
This video is characterized in that it is equipped with an SDH addition section (3) that adds overhead to the tip of 4 data, and enables transmission of multi-channel video signals and alarm information for each channel when using synchronous digital hierarchy. Signal multiplexing method.