JPH0244825A - Transmission device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmitting device in a digital transmission system.

[Conventional technology]

2. Description of the Related Art Systems for recording video signals on a digital VTR and encoding and transmitting the reproduced video signals are conventionally known. Its configuration is shown in FIG. The analog video signal input to the input terminal 10 is a video tape recorder (V
TR)12. The analog video signal output from the VTR 12 is input to the coder 14, where it is encoded and band-compressed. The output of the coder 14 is
The signal is inputted to the decoder 18 on the receiving side via the decoder 18, where it is decompressed and D/A converted. Therefore, an analog video signal is obtained at the output terminal 20.

In the VTR 12, 22 is an A/D converter, 24 is a band compression circuit, 26 is a magnetic tape, and 28 is a band compression circuit 24.
30 is a D/A converter. In the coder 14, 32 is an A/D converter;
4 is a band compression circuit for transmission. In the decoder 18, 36 is an expansion circuit that performs expansion processing corresponding to the band compression circuit 34, and 38 is a D/A converter.

Further, as an application of the above signal transmission system, a system is known in which a large number of receivers each having a decoder 18 receive desired programs from a plurality of VTRs 12 (video sources) of a sender via an exchange. . In this system, conventionally, the transmitting side includes a VTR 12 and a coder 14.
A large number of transmitting devices were provided, and the output of each transmitting device was connected to the above exchange.

[Problem to be solved by the invention]

However, in the conventional example described above, A/D conversion and compression/expansion processing are performed inside the VTR 12, and further A/D conversion and compression/expansion processing are performed before and after the transmission path 16. In other words, the same processing is duplicated, and as the configuration becomes more complex, it takes more time to assemble the circuit, lowers reliability, increases price, increases weight, and makes it difficult to downsize. Various shortcomings arise. When a large number of senders and a large number of receivers are connected via an exchange, the above-mentioned drawbacks become more pronounced because of the aggregation of a large number of devices.

Therefore, an object of the present invention is to provide a transmitting device that eliminates such drawbacks.

[Means to solve the problem]

A transmitting device according to the present invention is a digital transmission system comprising a coder, a transmission line, and a decoder, wherein the coder includes a band compression means and is provided with a recording and reproducing means for recording and reproducing a compressed signal by the coder. .

[Effect]

Since the recording/reproducing means records the compressed signal by the coder, there is no need for the recording/reproducing means to independently perform compression processing. Therefore, processing related to compression/expansion is simplified, leading to a simpler and more compact configuration.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. The analog video signal at the input terminal 40 is input to a coder 42 where it is A/D converted and band compressed. coder 4
The output (compressed data) of No. 2 is input to a digital data recorder (hereinafter abbreviated as DDR) 44 and recorded on a recording medium such as a magnetic tape. The reproduced data of the DDR 44 is sent to the transmission line 48 via the switch 46.

By connecting the switch 46 to the b contact side, the output of the coder 42 can be sent to the transmission line 48 in real time. The data transmitted through the transmission line 48 is input to the decoder 50, where it is processed in the opposite manner to the processing by the coder 42 and returned to the original bandwidth. The output terminal 52 has
An analog video signal is obtained.

In the coder 42, 54 is an A/D converter, 56 is a band compression circuit, in the decoder 50, 58 is an expansion circuit that performs expansion processing opposite to that of the band compression circuit 56, and 60 is a D/A converter.

FIG. 2 shows a block diagram of an arrangement based on the arrangement of FIG. 1, which allows multiple recipients to access multiple video sources via a switch.

62 is an analog signal input terminal, 64 is an A/D converter 6
6 and a band compression circuit 68; 70 is a DDR
, 71 is a signal line that does not use DDR, and 72 is a large number of DDs.
A group of switches that distributes the output of the coder 64 to either R70 or the signal line 71, 74 is an exchange switch having an exchange function, 76 is a transmission path, and 78 is a decoder equipped with an expansion circuit 80 and a D/A converter 82. .

In FIG. 2, the compressed data that has been A/D converted and band-compressed by the coder 64 is converted into a desired DDR by the switch 72.
70 or applied directly to exchange switch 74 via signal line 71.

A receiver equipped with a decoder 78 accesses the DDR 70 in which a desired program or data is recorded via the transmission path 76 and the exchange switch 74, receives the reproduced data, decompresses it in the decompression circuit 8o, and decompresses it in the decompression circuit 8o. A converter 82 converts it into analog. This allows an analog video signal to be obtained.

In the above embodiment, the case where both the input and the output are analog signals is taken as an example, but of course, both the input and the output may be handled as digital signals, and in that case, the coder 42,
64 A/D converters 54°66 and decoders 50.78
(7) The D/A converter 60°82 is no longer necessary, resulting in a simpler configuration.

It goes without saying that various types of recording media for the DDR 44, 70 can be used, such as magnetic tape, magnetic disk, optical disk, and magneto-optical disk.

〔Effect of the invention〕

As can be easily understood from the above description, according to the present invention, there is no duplication of processing during signal transmission and the configuration is simplified, making circuit assembly easier and improving reliability. Furthermore, it is possible to reduce the cost and make the device lighter and smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a configuration of an embodiment of the present invention, FIG. 2 is a block diagram of a system in which multiple recipients access multiple data sources via an exchange, and FIG. 3 is a configuration of a conventional example. It is a block diagram.

Claims (1)

[Claims] 1. A digital transmission system comprising a coder, a transmission path, and a decoder, wherein the coder includes a band compression means, and a transmitter is provided with a recording and reproducing means for recording and reproducing a signal compressed by the coder.