Apparatus for digital signal transmission

The invention relates to an apparatus for transmitting digital signals via a transmission system to which a plurality of terminals with is connected to different bandwidth requirements.

In circuit- and HF-based networking of various broadband Devices, it is known (ETSI95), virtual channels on access mechanisms such as Carrier Sense Multiple Access <i>(CSMA) to manage.</i>Here, the equipment is a broadband transmission channel available found to by waiting a transmission gap, optionally with additional features to ensure orderly Traffic, is accessed.

Furthermore, the management of access is through global Synchronization measures known (ITUT90, CTIA92). In this case are, starting from a central system architecture, pilot and Synchronization channels provided that in all terminals defined minimum intervals are intercepted. The terminals have therefore a standby mode of the switched on again each device must first be reached again.

A prerequisite for the implementation of the above systems is the Similarity of the devices used. This means that in the case of broadband CSMA access all devices conform to the system, under Circumstances at very high speed, can send and receive must, as z. B. is the case in a computer network. On broadband CSMA access implies also a multiple access, the on Time division builds. In this case, need to correct the channel influences additional measures such as adaptive equalization are taken.

In the case of synchronous access all devices have a means for possess listening to the channel and to building upon synchronization. Furthermore, the devices can only from a standby mode out are driven. A spontaneous sending control information is not possible.

For digital audio-video networks (AV) networks, the requirement applies the not terminal homogeneity. Rather, here of very complex, bidirectional devices, such as digital video recorders, Satellite receivers, television receivers, etc., to very simple, unidirectional devices, such as remote controls, all Categories represented. The bandwidth requirements ranging from few bps for building controls and remote controls of some 10-100 kbps for audio applications to some 10 Mbps for television and Video applications. Such devices can variety with a simple Network architecture will not be realized.

Starting from this prior art, the invention has the task providing a device for transmitting digital signals via a Transmission network to which is connected a plurality of terminals is to design such that it can be used flexibly.

This object is achieved in a device having the in the preamble of Claim 1 features specified by the in the characterizing part solved the stated claim 1. advantageous Refinements and developments emerge from the dependent Claims.

The advantages of the invention are, in particular, that means the claimed device the different bandwidth requirements connected to the transmission network terminals in such a way Account that different transmission channels Bandwidth made available, the flexibility of the terminals are and effectively usable. In particular, the to the transmission network connected terminals different in your electronics be constructed. For example, need simple unidirectional Control units which emit only low-rate control information and therefore only need a narrowband transmission channel, no for broadband and optionally at high speed success forming transmitting and receiving equipped transmitting and Receive electronics. Further, in a device according to the Invention control information low bandwidth, for example, of emitted a wideband video signals processed video recorder is also transmitted via the narrowband transmission channel are, so that no broadband channel wasted for these purposes becomes.

By means of the features specified in claim 4 features is the effectiveness of Signal transmission by an adaptation of the wideband audio / video transmission channel to the respective existing bandwidth needs signals to be transmitted further increases.

Further advantageous features of the invention result from their exemplary explanation with reference to FIG. This shows a block diagram of a hierarchical digital audio-video transmission system, as For example, in a large building complex as an internal company Information - and control system or in a family home as House transmission system can be used.

In this audio-video transmission system with the numeral 1 a Variety of simple unidirectional or bidirectional network subscribers as For example, remote controls, and home installation components designated. These simple unidirectional or bidirectional network participants each connected to the narrowband transmission channel 3 and can use this control information to another of the simple transmitted uni- or bi-directional network, or control information received from other network nodes. The tax information are preferably transmitted at a low data rate, so that the Transmit and receive electronics in these devices comparatively can be implemented inexpensively. Access to this narrow band Transmission channel 3 may occur spontaneously and, for example on countries basically known Carrier Sense Multiple Access (CSMA) - Principle based. This access principle is characterized in that the channel monitors the occurrence of a transmission gap and this Transmission gap from the terminal for transmission of control information is used. Optionally, the access to the narrowband Transmission channel 3 may also be dependent on the presence of other criteria. For example, the different terminals different be assigned priorities.

Furthermore, the goods designated by the reference numeral 1 simple unidirectional or bidirectional network subscriber and control information on each one emit variety of complex network subscribers or of these receive. The complex network stations are generally by the reference numeral 2, are also on the narrow Transmission channel 3 is connected and also have a transmitting and Receiving electronics, which narrow band signal for transmission over the Transmission channel is necessary. In this complex network subscribers If it is terminal, the control information both lower Bandwidth as well as audio and / or video signals with a high bandwidth can send and / or receive, for example, digital VCR, television receivers, radio sets, videophones, Satellite receiver, etc. The data received from these devices or transmitted control information is, for example, Program selection information, volume information, Drive information, power on, switch-off and Brightness information or acknowledgment information the respective transmitting device the proper receipt of Confirm transmitted information.

Furthermore, the narrowband transmission channel 3 is also used to transfer control information between the individual with the reference numeral 2 designated complex network subscribers used.

The complex is provided overall with the reference numeral 2 Network users remain to a wide-band audio / video transmission channel 4 connected, which for uni- or bidirectional Transmission of audio and / or video signals is provided. This wideband audio / video transmission channel 4 is preferably in a Plurality of dynamic subchannels divisible, wherein the bandwidth and Data rate of each of these sub-channels can be adapted to the respective requirements. The distribution referred to in sub-channels may be on a principle of known transmission methods are based, in which the available standing transmission channel to a multiplex transmission of a plurality various signals is used, for example, the Time-division multiplexing method, the OFDM method or the CDM method. By means of that allocation is advantageously the circumstance taken into account that for the transmission of audio and / or Video signals of different standards required bandwidth is different. For example, the for transmitting an audio signal required bandwidth less than that for transmission of a still image required bandwidth, which in turn is less than the transfer to a moving image necessary bandwidth.

The management and quality control of said dynamic subchannels the wideband audio / video transmission channel 4 is taking place Using the narrowband transmission channel. 3

For this purpose, for example, from a video recorder to a narrowband transmission channel 3 connected, not shown central control unit in which it is a part of the or act terminals to a part of a separate control unit can, via the narrowband transmission channel 3 a request signal supplied, which is communicated with the central control unit that, by means the VCR a transmitted in a particular satellite channel Television broadcast to be recorded. The control unit checks as Response to this request signal, whether a subchannel of appropriate bandwidth the wideband audio / video transmission channel 4 for transmitting Satellite TV signals are free, provide where appropriate predetermined hierarchical criteria governing the establishment of such Subchannel and allocates this sub-channel in terms of quality control and the VCR and satellite receiver to. The relevant Control information is the satellite receiver and the VCR from the central control unit in each case over the narrowband supplied to transmission channel 3, so that the electronics of the video recorder and the satellite receiver to the desired signal transmission via the wideband audio / video Übetragungskanal 4 can be adjusted.

This setting must, for example with respect to the respective required Bandwidth of each frequency position, the relevant time frame, etc., done.

By means of the device described is, after all, a novel, created hierarchical and digital audio-video transmission system, which a narrow-band transmission channel 3 for uni- or having bi-directional transmission of control signals and under the Using the management and quality control of a still existing broadband transmission channel 4 takes place through which the transmission broadband audio and / or video signals is carried out. Of the broadband transmission channel 4 is preferably in a plurality of dynamic subchannels divisible, so that the terminals at different bandwidth and speed requirements occurring needs to be carried in a flexible way bill can. The described system can completely for transmission and various mutually independent signals over one and the same transmission network used, with the party to be transmitted signal a matched to this signal transmission channel is provided.