Videophone
A videophone is a telephone with an additional video screen. Cell phones can also be used to establish picture connections.
functionality
When connecting two video telephones that are compatible with one another , mutual visual contact between the call partners can be established. If more than two partners are connected to each other, one usually speaks of a video conference system . For deaf people who otherwise cannot use the telephone, communication with sign language is possible.
Germany
The idea of the videophone is as old as television . Even before the Second World War , first attempts were made in Germany using a method developed by Georg Oskar Schubert . In 1936 the first public telephony service was introduced between Berlin, Leipzig, Nuremberg and Munich. At that time, one could picture telephony with one another from public television stations. Later further attempts were made to establish video telephony, for example in 1985 with the BIGFON (Broadband Integrated Glass-Fiber Optical Network) project of the Deutsche Bundespost , which was later expanded into a forerunner broadband network VBN in Germany and the 20 largest cities in Germany Association. The image and sound signals were transmitted digitally at 140 Mbit / s, in the best television quality, without compression , circuit-switched and with almost no delays . Large companies such as IBM and Daimler used this network at the time for interactive training of employees in their branches. This network was switched off around 1992, for reasons of charging policy and because u. a. a new ATM technology standardized by the ITU-T should be introduced. ATM was never accepted as the basis for video telephony.
Video telephones with a small display were occasionally offered for the analog telephone network and later for ISDN , but were not particularly successful on the market due to their high acquisition costs and poor image quality. However, these devices have been well received in application studies for audio-visual communication in the medical field (patient ↔ specialist), in the care of elderly or sick people or the deaf in homes or private apartments. Later, with the help of the new DSL transmission technology, a higher bandwidth was possible than with ISDN, so that the Internet became the basis for video telephony with the use of PCs , webcams and the corresponding software .
Switzerland
BASKOM, a circuit-switched, application-oriented 140 Mbit / s test network with 30 subscriber connections was put into operation in 1991. It offered two services: video telephony (video telephone in color television quality with direct eye contact) and video library retrieval (film retrieval from central moving image storage).
In 2004, Mobily Procom GmbH, in collaboration with Siemens, developed a video telephone for the deaf in Switzerland, TeleSIP , based on the Internet protocol. The project was canceled again after a field test, officially because the software was too error-prone. This software should have combined the functions video telephone (via webcam), writing telephone , live chat and acoustic telephone in one device. At that time, Siemens / Procom had competition with the videophone (model D-Link DVC-1000 ) offered by various providers in the hearing impaired sector . In contrast to TeleSIP, this does not require a computer, but chat is not possible. This product as well as newer products, which mostly work according to the SIP standard, are used today by a minority of the deaf. The majority use video chat software from established manufacturers such as Skype .
Mobile phones as terminals for video telephony
Since 2005, mobile phones equipped with a camera have also offered the option of making a video call. For this, a powerful cellular network such as B. UMTS and appropriately equipped devices that have a lens on the front in addition to the usual lens on the back of the cell phone. A traditional Internet connection can also be used as a transmission technology, for example if a WLAN is available; Skype or WhatsApp can then be used as software . Together with the iPhone 4, Apple introduced FaceTime .
literature
- Dunckelmann, Henning: Video communication in broadband networks as a medium for the deaf: sociological research accompanying the BIGFON system experiment; Final report of a research project . IZT (Institute for Future Studies and Technology Assessment) on behalf of the Deutsche Bundespost. Berlin; 1992. ISBN 3-929173-00-X
Web links
- Guideline "Accessible hearing and communication in the world of work": Additional aids and services for making calls The Hörkomm.de project supports the inclusion of hard-of-hearing employees.
Individual evidence
- ↑ https://w4.siemens.de/siemens-stadt/schubrt0.htm ( page can no longer be accessed , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ http://www.fernsehmuseum.info/fernsehen-bis-1945-fernsehsprech.html
- ↑ PTT, Technische Mitteilungen, No. 3/1991, Bern, year 69, pages 95ff.
- ↑ http://www.ghe.ch/de/list.asp?ID=140
