Telephony
The telephony (since 1996 outdated notation: Telephone; Greek coinage τηλεφωνία tēlephonía , from ancient Greek τῆλε tele "far, far" and φωνή phone "voice") refers primarily voice communication via a technical device (eg. Telephone network ). The first researcher to succeed in this form of transmission of voice data as early as 1860 was Philipp Reis .
Voice transmission is achieved either through analog telephone services or through digital ones, for example a telephone network (e.g. ISDN ), a radio network (e.g. GSM ) or a packet-switched data network (e.g. IP telephony ). It is important that the delay is as short as possible (a maximum of 200 ms is acceptable) and good sound quality (speech intelligibility is usually transmitted because of the frequency range between 300 and 3400 Hz).
Terminal devices in a wired telephone network are telephones , in a wireless radio network mobile telephones and in IP telephony a special IP telephone (VoIP or SIP telephone ) or a computer . Answering machines or voice mailboxes are available for automatic call acceptance . Radio devices are used in radio services.
When communicating via a telephone network, the destination is addressed via a numeric telephone number ; when using IP telephony, it is addressed via the IP address , a user name or an ENUM telephone number.
See also
Other meanings
In addition, telephony describes the unwanted transmission of sound vibrations, z. B. from the speaker to the microphone . This creates high whistling tones and echoes . With hearing aids , these whistling tones are often not perceived by elderly wearers, but they are by younger people around them.
The mechanical effect of the loudspeaker or sound waves and structure-borne noise on the control grid of an amplifier tube , on resonant circuits or other components is called microphony . This creates noise.
Ventilation systems can also have a telephony problem: a so-called telephony damper made of mineral wool is installed to allow air to pass through but to prevent sound transmission.
As more importance with telephony or Phonie the voice called, especially in comparison to the Telegraph . Telephony in this sense (for example with Jedermannfunk ) does not require a telephone network-like form of organization.
Web links
- Historical archive and library PTT - files and library holdings on the history of telephony (Switzerland)