Data transmission

With data transfer or information transfer is referred to all the methods (useful) information from a transmitter ( source of information ) to a receiver ( information sink ) transmit. Technically, to a physical quantity (eg voltage or the frequency of electromagnetic waves ) varies with time measured from the transmitter and the receiver. Transmission method for alphabetic texts are for example the telegraph and facsimile (fax). For the transmission of moving or still pictures serve telegraphy and television.

Analog transmission of information

In the analog transmission of information of the physical size, the corresponding data imprinted continuously. Each value is in a specified interval admissible and relevant at all times.

The technical impossibility of the communication channel (ie, the physical size) as well shielded from the outside world that this is not affected by it, and the technical impossibility of accurately measuring the physical quantity in time lead to loss of information which not even by amplifier can be prevented.

Digital information transfer

In the digital transmission of information in the physical size of the corresponding data imparted discretely. Here are several noncontiguous areas ( disjoint ) intervals permitted that are relevant only in certain disjoint, not directly successive time intervals.

Within the relevant time intervals, the value of the physical quantity is allowed to vary only within a permissible interval. The receiver then measures once in each relevant time interval, the physical size. The interval sequence of the physical size of the relevant time intervals now contains the information. Due process is possible by adequate shielding of the physical size of the outside world, a suitable choice of the intervals and using error-correcting codes to reduce the probability of loss of information arbitrarily far to the detriment of the transmission rate.

In computers constantly find ( digital ) data transfers take place, for example from disk into memory. The first attempts to connect computers for data exchange there for some time. At the beginning of this often direct connections were similar to today's serial port or the parallel port with specific link schemes. Later, the data transmission over telephone lines or modems with acoustic and simple protocols such as XMODEM, YMODEM, ZMODEM or Sealink protocol was performed. These were later supplemented by bi -working protocols such as Hydra or Janus, which allow the simultaneous transmission of files in both directions. In this case essentially only data within the meaning of files have been transferred. A first cross-linking was carried out via mailboxes. Data transfer is now network-based as a rule. The internet protocol is almost always used, even if this modem connections in the logs of the lower transfer layers (see OSI model ) is packaged. Go out the data transmission via a private network and the connection is to a different network only temporarily and it is used mainly for file transfer, so we often speak of a long-distance data transmission.

Data transmission

Data transmission is also used as a legal concept in data protection law.

In Germany is understood here under according to § 3 Paragraph 4 No. 3 BDSG " the Announce stored or obtained by data processing of personal data to a third party in such a manner that the data is passed to the third party or the third party to inspect or held ready for retrieval data realizes or obtains ". The transmission falls under the heading of data processing.