JPS62281627A - Digital signal transmission system - Google Patents

Abstract

PURPOSE:To transmit many types of modes and data with a small number of bits by transmitting a synchronizing signal, a service signal including each type of mode and data, and applying time division multiplexing to transmit data signal. CONSTITUTION:The synchronizing signal, the sevice signal including each type of mode and data and the data signal are transmitted after applying time division multiplexing. A main receiver 10 discriminates the mode information on the service bit of the received digital data signal and turns on pilot lamps 103a-103c to show the type of the mode of a selected program. Thus the types of mode and data are detected by the service signal and at the same time the data signal of the detected type of mode and data can be extracted. Thus it is possible to transmit many types of modes and data with a small number of bits.

Description

[Detailed description of the invention] Detailed description of the invention The present invention will be explained in the following order.

A. Field of industrial application B. Overview of the invention C. Prior art D. Problems to be solved by the invention E. Means for solving the problems (Figs. 1 and 2) F. Effect G. Example G ID M S System configuration (Figure 3) Configuration of G2 transmission data format (Figures 1 and 2) Reception operation of G3 transmission data ■ (Effect of the invention A Industrial application field This invention is a digital transmission system using CATV lines etc.) It relates to a signal transmission method.

B. Summary of the Invention The present invention is a digital signal transmission method using a CATV line, etc., in which a synchronization signal, a service signal including a mode and data type, and a data signal are time-division multiplexed and transmitted. This allows data of many types of modes and data types to be transmitted with a small number of bits as a signal.

C Conventional technology Conventionally, so-called C technology transmits television broadcasts by wire.
ATV systems were put into practical use. CATV in recent years
It has been proposed to transmit various signals (computer data, high-quality audio signals, etc.) other than normal television broadcasting using the transmission path of the system.

D. Problems to be Solved by the Invention However, television broadcasting transmitted by a CATV system generally has a large number of channels, and the transmission path has almost no room to transmit the various signals mentioned above. Therefore, as a CATV system capable of transmitting the various signals mentioned above, 'r3J' efficiently transmits signals (especially digital signals 3+).
There was a need to develop a system that could

The present invention takes this into account and aims to provide a digital signal transmission system that can transmit a large amount of information with a small number of bits.

E. Means for Solving the Problems The digital signal transmission system of the present invention time-division multiplexes a synchronization signal, a service signal including a mode and data type, and a data signal, as shown in FIGS. 1 and 2, for example. It is designed to be transmitted.

F. Effect The digital signal transmission system of the present invention transmits the service signal including the mode and data type by time division multiplexing with the data signal, thereby detecting the mode and data type in the service signal. It is possible to extract data (m%) of modes and data types, and to transmit data of many types of modes and data types with a small number of bits.

G. Embodiment Hereinafter, an embodiment of the digital signal transmission system of the present invention will be described with reference to the accompanying drawings.

G. Configuration of MS System The digital signal transmission method of this example will be described with reference to an example in which it is used in a digital multimedia service system (hereinafter referred to as a DMS system) as shown in FIG.

In this DMS system, a transmission device (1) is installed on the CATV center A side, and after multiplexing various computer data signals, digital audio signals, etc. obtained by the transmission device (1) using the method described later, this digital multiplexing is performed. The signal is modulated into a signal of a band corresponding to one channel of the television broadcast signal and is supplied to the transmission signal mixing device (5). Then, in this transmission signal mixing device (5), the digital multiplexed signal is mixed with the television broadcast number 14 of multiple channels by changing the carrier wave, and this mixed signal is provided in the CATV center A. Nayuna of U number (6a), (6b)
, (6c) .

This tuner (6a), (6b), (6c
) are installed, for example, as many as the number of receivers who have contracted to use this CATV system, and each tuner (6a) is installed.

(6b), (6c), . . . indicate that the channel is selected by a selection signal supplied from the receiving household B Ill, which will be described later.

Then, the signal of this designated channel is demodulated into a baseband demodulated signal, and each tuner (6a)
, (6b), (6c)... Photoelectric converter (7a), (7b), (7c)
This photoelectric converter (7a
), (7b), (7c)... convert the demodulated signal into an optical signal, and convert this optical signal into a photoelectric converter (ma).
, (7b), (7c) . . . a photoelectric converter (9a) installed on the receiver side of each home or the like.

(9b), (9c)...' have optical fiber cables (8a).

(8b), (8c)... If this photoelectric converter (9C) is installed, for example, in the home of recipient B, this photoelectric converter (9c) is connected to the main receiver (lO) on the receiving household B side, and the electrical i
The optical signal obtained by the photoelectric converter (9c) converted into a summer tone signal is supplied to the main receiver (10). This main receiver (10
) has a front panel configured as shown in FIG. 4, and the supplied demodulated signal is sent to the TV adapter (IQa) as a signal as it is, or to the output terminal (Job) connected to each heel regeneration device etc. to be described later. (iof) is supplied as a signal that has undergone predetermined signal processing, and is connected in series to the first sub-receiver (11), second sub-receiver (12), etc. 11), (12)
Supply to... In addition, the reception channel can be selected by a remote controller (IOR) that sends a control signal to this jE receiver (10) or this main receiver (10), and a reception channel selection signal is sent from the main receiver (10). the path opposite to that of the demodulated signal described above, that is, the photoelectric converter (9c)
, optical fiber cable (8c) and photoelectric converter (7C)
is supplied to the tuner (6C) on the CATV center A side. With this selection signal, the tuner (6C) selects one of the multiple channels (6C) supplied from the transmission signal mixer (5).
It demodulates only the signal of the desired channel from among the signals and supplies it to the main receiver 1110) on the receiving household B side. In this main receiver (10), when the supplied demodulated signal is a signal of a television broadcasting channel, the main receiver (10) feeds the modulated one word as it is to the TV adapter (10a); ) adjusts the demodulated signal, which is a television broadcast signal, and sends it to the television receiver (13
), and the television broadcast is viewed on this television receiver (13).

Further, when the supplied demodulated signal is a channel signal of a digital multiplex signal, predetermined signal processing is performed and a digital audio signal or data (digital code) is supplied to any of the terminals (10h) to (10f).

The digital multiplexed signal is sent to the sending side, that is, CATV center A.
In 1l11, the transmission is controlled by the system controller (3) in the transmission i 9 tll, and the data converter (
2), i.e., a digitized still image signal obtained at terminal (2a), a computer data signal obtained at terminal (2b), a telegraph data signal obtained at terminal (2c), and a digital data signal obtained at terminal (2d). A facsimile data signal or the like is converted into a signal that is formatted as described below under control from the system controller (3).

Then, the converted data signal is supplied to the data transmitter (4), and the CD ROM?played by the CD ROM player (4b). 1 playback data, a 2-channel stereo digital audio signal (16-bit signal according to standards such as CD) obtained at terminal (4c), and terminal (4c).
The monaural digital audio signal (8-bit signal with non-linear modulation) obtained in step 4d) is supplied to the data transmitter (4). Necessary signals among the supplied signals are multiplexed in a format to be described later by the data transmitter (4) according to instructions from the system controller (3), and are made into a digital multiplex signal ff1fj, and the modulator (4a ) into a signal with a band corresponding to one channel of television broadcasting (*'4).When performing this multiplexing,
The mode and special information of the multiplexed data are multiplexed using the format described later. The modulated digital multiplexed signal is then supplied to a transmission signal mixing device (5).

For example, when the tuner (6c) selects the channel corresponding to the digital multiplexed signal transmitted in the manner described above based on the selection signal from the receiver B side, if the channel corresponding to the digital multiplexed signal transmitted as described above is It is supplied to the main receiver (10) on the side of receiver B. When this digital multiplex signal is supplied to the main receiver (10), it is For example, the mode and type information of the signal supplied to the monitor receiver connected to the output terminal (10e) is displayed.
The mode and type information of this supplied signal is output to the output terminal (
10e. Then, the receiver sees the display on the monitor receiver and operates the front panel of the main receiver (10) or the remote controller (1, OR) to select the necessary data etc. from the multiplexed digital signal. Then, the selected signals are sent to the corresponding output terminals (10b) to (10
f). Immediately, for example, when a digital audio signal or digital audio signal is selected, this digital audio signal or digital audio signal is fed to the terminal (10b) connected to the stereo playback device, and when a playback data signal of the CD ROM is selected. Sometimes C
The reproduced data signal of this CD ROM is supplied to the terminal (10c) connected to the DRO-data decoder, and when the facsimile data signal is selected, this facsimile data signal is supplied to the terminal (10d) connected to the facsimile machine. When you select the image option, this static image signal is supplied to the terminal (10e) connected to the monitor receiver, and when you select the 21 computer data (no option), the static image signal is supplied to the terminal (IQf) connected to the personal computer. This) supplies computer data signals.

In this way, the CATV line is used to send digital data (g
A DMS system is configured in which the signals are supplied.

Structure of G2 Transmission Data Format Next, the format of the digital data signal supplied to each receiving household such as receiving household B on the CATV center 8 side in the above-mentioned DMS system will be explained.

FIG. 1 is a diagram showing an outline of the format of the digital data signal of this example. This format is composed of a large number of frames, and one frame is composed of a 168-bit H or L binary signal. Also, ■The frame period is 1/4
At 4.1kHz, the transmission speed is approximately 22.7μs.
It becomes ec. Then, as shown in Figure 1, 1
A multi-frame is constructed, 64 multi-frames constitute one super frame, and 5 super frames constitute one multi-super frame. Therefore, one multi-superframe takes 29m5ec of transmission time, and this one
It is assumed that a multi-superframe is one division of transmission, and the mode described below does not change within each multi-superframe.

The structure of each frame is shown in order from the beginning with the frame synchronization signal (
FS) 8 bits, service bit (SB) 4 bits,
The data consists of 156 bits, and the 156 bits of data are such that four different data of programs #1 to #4 are sent one bit at a time by time division multiplexing. That is, the data is sequentially from the beginning, 1st bit of program #1, 1st bit of program #2.
Bit, 1st bit of #3, 1st bit of #4, #1
Then, 39 bits are sent for each program #1 to #4 in one frame. Also, frame synchronization (
at'5+c, only the first frame of each superframe becomes a superframe synchronization signal (SFS).

Here, in addition to the computer data described later, the data to be transmitted in this example is a 16-bit linear modulated digital stereo audio first word as an audio signal, and an 8-bit non-linear audio signal as an audio signal. It is a modulated digital monaural audio signal. For this reason, for example, in the case of an audio signal, each frame has 16 bits on the left and right, a total of 3 bits.
It becomes a 2-bit signal, which is 1 of the 39 bits in one frame mentioned above.
One channel can be transmitted by program, and the audio signal is a signal of 8 bits per frame, and the above-mentioned 1 frame 3
One 9-bit program can transmit 4 channels. In addition, the amount of transmission of computer data signals (signals processed by the data converter (2) in the example in Figure 3) that are not audio signals or voice signals varies depending on the service speed, and there is a service that sends one bit per multiframe. Speed (11,0
25Hz) is [0, for r 2fo, 4fo
, 8fo, 16fo + 32fo + 64fo,
Service speeds of 128fo and 156fo can be selected, and in the case of fO service speed, 1 with the l program.
56 channels (types) of data can be transmitted, 156f
In the case of a service speed of o, data of one channel (fffi ff1J1) can be transmitted by one program.

Also, during this data transmission, slot numbers from 1 to 156 are assigned to each data bit for each multiframe,
This data l for each slot number is marked as data information of a service bit, which will be described later.

The content of the data thus transmitted is indicated by four service bits in each frame. This service bit is the second bit in every multi-superframe.
It is configured as shown in the figure.

Figure '12 is a diagram showing only the service bits extracted from the transmission signal of one multi-superframe.
There are a total of 512 service bits in multiple superframes.
There are 0 bits, and each superframe has 1024 bits. The specific structure of the service bits is as follows: 4 bits of multi-superframe synchronization signal (MSFS), 12 bits of PGM mode signal, in order from the beginning of each superframe.
The multi-superframe synchronization signal is a high-level signal with all 4 bits in the first superframe of each multi-superframe, and all 4 bits in the other superframes are low-level signals. signal. In addition, the 12-bit PGM mode 1'(; is divided into 3 bits each corresponding to the programs #1 to #4 mentioned above, and each 3 bit is divided into 3 bits each as shown in Table 1 below. Used as code information for program data.

Table 1 In other words, in this example, six types of modes are prepared, Mode 1 to Mode 6, where Mode 1 is an emphasis-off 16-bit stereo digital audio signal reproduced from a CD, and Mode 2 is an emphasis-on 16-bit stereo audio signal reproduced from a CD. 16 of
Bit stereo digital audio signal, mode 3 is a digital audio signal obtained by digitally converting an analog signal into a signal equivalent to a CD, mode 5 is a data signal read out from CD ROO12, mode 6 is the mode information that there is no data in the corresponding program. shown. Also, mode 4 is program #1. #2 and program #3. #4
The mode information is different for program #1. At #2, one frame of 39-bit data signal processed by the data converter (2) of the example in FIG. 3 is shown as mode information, and program #3. When #4, 8 of 4 channels
Bit monaural output (shown as mode information).

In addition, the 1008-bit data information G for each superframe is divided into 63 slots of 16 bits each.
It is possible to show 315 slots in one multi-superframe, but in reality only the last 3 slots (
48 bits) are unused, representing a total of 312 slots. Of these 312 slots, the first 156 slots correspond to slot numbers 1 to 156 of the data bits of program #1, and the latter 156 slots are This corresponds to slot numbers 1 to 156 of the data bits of program #2. Also, each slot has 16 slots.
Among the bits, the nij half 8 bits are used as address data of θ to 255 indicating which channel the data bit of each corresponding slot belongs to, and when the address is 0, the corresponding data bit is no signal. Show that.

The latter 8 bits are password data from O to 255 indicating the password of the data bit of each corresponding slot/slot, and only the data of the password contracted in advance for each receiving household can be received. In this case, it indicates that there is no restriction on data reception by password.

As described above, the format of the signal sent from the transmission device (11) is configured.

Reception operation of G3 transmission data The operation when the receiving household B of the DMS system shown in FIG. 3 receives transmission data sent in a format higher than or equal to the above format will be described below.

First, the main receiver (10) (or remote controller (IOR)) of receiving household B selects reception of the digital data signal sent from the transmission device (1). That is, for example, by operating the numeric keypad type channel selection switch (101) of the main receiver (10) as shown in FIG.
A transmission channel for this digital data signal is selected from CATV broadcast channels, a tuner (6c) is made to perform jl IM of this digital data signal, and a demodulated signal of this digital data signal is supplied to the main receiver (10). . Here, this digital data signal is program #
Since there are four programs, #1 to #4, the recipient must press the program selection switch (102a) on the FD machine (10).
- (102d) and select the desired program.

At this time, the main receiver (10) distinguishes the mode information of the service bit of the supplied digital data signal and turns on the display lamps (103a) to (103c) to indicate which mode the selected program is in. We will inform you by.

That is, for example, if the mode is an audio signal (mode L in Table 1)
, corresponds to 2.3), the indicator lamp (103a
) and turn on the monaural audio signal (Program # in Table 1).
3 and 4), the display lamp (103b) is lit, and other data signals (corresponds to mode 4 for programs #1 and 2 in Table 1 or mode 5 for all programs). When it is, the indicator lamp (1
03c) lights up. When the selected program is an audio signal, only the audio signal of this program is extracted and supplied from the main receiver (10) to a terminal (10b) connected to a stereo playback device. Also, when the selected program is an audio signal, there are 4 channels of signals in 1 program, so the receiver can receive 4 channels of signals.
audio channel selection switches (104a) to (,1
04d), and extracts and supplies only the audio signal of the selected channel from the main receiver (10) to the terminal (10b). In addition, when the selected program is another data signal (excluding CD ROM playback signals), a maximum of 156 channels are transmitted for one program depending on the transmission signal at that time.
A receiver operates a channel selection switch (101) to select a desired channel. However, at this time, since this channel operation is to select a data channel, for example, the data channel selection switch (101a) is operated at the same time. By operating in this way, the presence or absence of the corresponding data channel is detected by determining the service bit of the selected data channel, and the password of the corresponding data channel is detected, and the reception contract for the corresponding data channel is confirmed in this receiving household B. It is determined whether the received data can be received. Then, only when there is data to be transmitted on the selected data channel and reception is possible in this receiving household B, for example, the service indicator lamp (105) lights up to inform you of this, and the data on this data channel is Only the signal is extracted and this data signal is supplied to one of the terminals (10d) to (10f) connected to a device such as a computer that requires data. Also, if the selected program is a CD ROM playback signal, this CD ROM
Extract only the OM playback signal and connect this CD RO? to the terminal (10c) connected to the CD ROM decoder. A reproduction signal of I is supplied.

In this way, according to this example, it is possible to select one program channel of the digital data signal supplied by the main receiver (10), and to supply the selected data to each device.

The data mode, data channel, etc. can be easily determined based on information such as the mode of the service bit. Therefore, by simply providing a small number of service bits in the format of this example, signals from a plurality of motes and channels can be sent simultaneously in a time-division manner.

Furthermore, since the service bit includes password information, it is possible to select households that can receive each data.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations may be adopted without departing from the gist of the present invention.

I4 Effects of the Invention According to the digital signal transmission system of the present invention, it is possible to detect the mode and data type in a service signal and extract the data signal of the detected mode and data type. There is an advantage that data of +ti modes and data types can be transmitted.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining an embodiment of the digital signal transmission system of the present invention, FIG. 3 is a system diagram showing an example of a DMS system, and FIG. 4 is a diagram showing an example of a receiver (M machine). (1) is a transmission device, (2) is a data converter, (4) is a data transmitter, (5) is a transmission signal mixing device, (6a),
(6b) and (6c) are tuners, (10) is a main receiver, A is a CATV center, and B is a receiving household.

Claims (1)

[Claims] A digital signal transmission method characterized in that a synchronization signal, a service signal including a mode and data type, and a data signal are time-division multiplexed and transmitted.