Internet acces via ADSL by Ralf Gall 
Where to go:
56k modem
cable TV
home of the seminar
The maximum transfer speed is not 33,6 kbps or 56 kbps. As the xDSL technology (Digital Subscriber Line) shows, transfer rates up to 9 mbps with ADSL (Asymmetric DSL) and even 52 mbps with VDSL (Very High Data Rate DSL) are possible. The technology behind is easy to understand: the telephone companies have defined a range of 3,3 kHz in which voice, faxes and data are transferred. So it is possible to send 35'000 bits per second through one telephone line. Theoretically a copper wire can transfer signals in a bandwidth up to several megahertz but only for short distances. The maximum distance between the two connection points is about five to six kilometers. At least in Switzerland this should be no problem as the telephone net is on a very high level. 

In the 60s Bellcore developed a new method: DSL (Digital Subscriber Line). With multiplexing several digital channels could be used parallel. The maximum transfer speed was limited to 160 kbps. There were two data channels with 64 kbps and a control channel with 32 kbps. This technology has been adapted worldwide and is called now ISDN. 

In the 70s HDSL (High Data Rate DSL) was developed on the base of DSL. HDSL provides 24 channels with a capacity of 64 kbps. The total capacity is 1,5 mbps. In the US this permanent line is called T1. In Europe 30 channels are available under the name of E1 and in Switzerland you can rent an ISDN multiplex line. Because of the high cost, this connection type is only for business users. 
Different is the ADSL (Asymmetric DSL) technology developed in the 80s by AT&T. Compared to the T1- or E1 connection, ADSL works (as the name says) asynchronous: The maximum download speed is 9 mbps, the upload speed is limited to 640 kbps. 


  • The normal telephone lines can be used
  • Max. download speed 9 mbps
  • Max. upload speed 640 kbps
  • An ADSL-modem is rather expensive (SFR 1500.--
  • An network adapter is needed (10 mbps)