Doug McNutt wrote: > FAX using a modem, my G4 has one built in, goes out in the form of quadrature > modulated (QAM) 1400 Hz carrier on a normal telephone line. Dual tone > multifrequency (DTMF) is used for dialing the number but not for data > transmission. > > Both the QAM and the DTMF are well within the voice band (300 to 3000 Hz) of > plain old telephone (POTS) service and must go through a filter if the same > telephone line is used for digital subscriber service (DSL). If the filter is > not used the wide band radio frequencies used for DSL can and will interfere > with the voice band transmission either FAX or audio. >
While the DSL signal can interfere with voice, particularly the Automatic Gain Control (AGC) in some phones, it's mostly there to keep voice band (including conventional modems) equipment from killing the DSL signal. Some stuff looks like a dead short at the high frequencies used by DSL. > When I get involved with DSL on a neighbor's or child's home I run a separate > pair to the DSL modem from the telephone entry point. I then install a filter > that isolates all other connections to the house. That way one doesn't have > to worry about all of those filters provided by the phone company. When Qwest > recently installed DSL here the installer actually did that for me with a > filter designed for the purpose. But I sure had to ask. > I did the same thing myself. Nice that my house came wired with six phone lines running around the house. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" --~--~---------~--~----~------------~-------~--~----~ You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list -~----------~----~----~----~------~----~------~--~---
