With data transmission or information transmission is basically refers to all methods that ( useful ) information from a transmitter ( source of information ) to a receiver (Informations valley ) forward .
Specifically on the technical level - and here in particular in communication technology and (as a subfield of this) communications technology - the transmitter varies a physical quantity (e.g. electrical voltage or the frequency of electromagnetic waves ) over time and this is then measured by the receiver.
Analog information transfer
In the case of analog transmission of information, the corresponding data is continuously impressed on the physical quantity . Each value is permitted in a defined interval and is relevant at all times.
The technical impossibility of shielding the communication channel (i.e. the physical quantity) so well from the outside world that it is not influenced by it, as well as the technical impossibility of measuring the physical quantity exactly, lead to a loss of information over time , which is also not due to amplifiers can be prevented.
Digital information transfer
With digital information transmission, the corresponding data is discretely impressed on the physical variable . Here are several not directly consecutive ( disjoint ) intervals allowed that are also relevant only in certain disjoint, not directly successive time intervals.
Within the relevant time intervals, the value of the physical variable may only vary within a permissible interval. The receiver then measures the physical quantity once in each relevant time interval. The interval sequence of the physical variable for the relevant time intervals now contains the information. Due to the process, adequate shielding of the physical size from the outside world, a suitable choice of intervals and the use of error-correcting codes make it possible to reduce the probability of information loss at the expense of the transmission rate as much as desired.
(Digital) data transfers take place continuously in computers , for example from the hard drive to the main memory . The first attempts to connect computers for data exchange have been around for some time. In the beginning, these were often direct connections similar to today's serial interface or the parallel interface with special link programs. Data was later transferred via telephone lines with acoustic couplers or modems and simple protocols such as XMODEM , YMODEM , ZMODEM or Sealink protocol. These were later supplemented by bi-directional protocols such as Hydra or Janus, which enable files to be transferred in both directions at the same time. Essentially, only data in the sense of files was transferred. The first networking took place via mailboxes . Today, data transmission is usually network-based. The Internet protocol is almost always used, even if it is packaged in the protocols of the lower transmission layers (see OSI model ) for modem connections . If the data transfer goes beyond your own network and the connection to another network is only temporary and it is mainly used for file transfer, this is often referred to as remote data transfer .
Data transfer is also used as a legal term in data protection law.
In Germany one understands here under to BDSG ", announcing stored or data processing gained personal data to a third party in such a way that the data is passed to the third party or third parties for inspection or retrieving data held ready looks at or retrieves ". The transmission falls under the umbrella term of data processing.
- Information theory
- Communication , bidirectional data transfer
- Transmitter-receiver model
- Digital signal
- Signal transition
- Parallel data transfer
- Serial data transfer
- Kristian Kroschel: data transfer. Springer Verlag, Berlin / Heidelberg 1991, ISBN 978-3-540-53746-5 .
- Peter Bocker: data transfer technology of data and text communication. Second edition, Springer Verlag, Berlin / Heidelberg 1983, ISBN 978-3-642-81973-5 .
- Martin Werner: Signals and Systems. 2nd completely revised and expanded edition, Friedrich Vieweg & Sohn Verlag, Wiesbaden 2005, ISBN 3-528-13929-3 .
- Andreas Walter, Torsten J. Gerpott: Compass telecommunications. Erich Schmidt Verlag, Berlin 2004, ISBN 3-503-07859-2 .
- Manfred Burke: Computer Networks. Concepts and techniques of data transmission in computer networks, BG Teubner Verlag, Stuttgart 1994, ISBN 978-3-519-02141-4 .