Konrad, After reading the TREGS email on metering tones some other questions occured to me. If you don't mind I would like to ask the following:
1. Do you know what mechanism is used to transmit the metering tones? 2. How it is generated? 3. In other words is it a sinewave with a small amount of distortion or a square wave? 4. What is the shape of the 12 KHz burst when transmitted? i.e Does it have a well behaved exponential rise and fall? 5. What is the duration of metering tone in Switzerland? I am asking these questions because I build a metering tone generator that transmits a burst with good exponential rise and fall. It designed mainly for testing German DAA and it works well. Although it wasn't needed at the time I also included Swiss capablities. I just want to make sure I didn't miss something. Reading the TREG email made me a little a nervous. I thought maybe metering tones in Switzerland might not be clean sinewaves and/or were transmitted at a much higher level than Germany. Thank you again. Amities, Duane _____________________________________________ On Wed, 26 Mar 1997, Konrad Gysi wrote: > Dear Duane, Ben, Rene.... > > Switzerland have the metering tones (12 kHz) enabled on all the lines by > default. But you can ask for disabling it when ever you want. > > best regards konrad, swisscom (new name for telecomm PTT switzerland) > > > >Dear Duane and Ben, > > > >It is indeed possible to have a modem approved without filters in them. > >They don't even check whether you remain connected, only whether > >your impedance isn't too low at 16KHz. It is unclear to me how well > >a modem would perform without it. The ones that had no filter but were > >used for demos worked pretty well with V.42 switched on. > >A difference between Germany and for instance Switzerland is that > >in Germany the metering tones are enabled by default on all lines, > >one has to request them to be disabled. Switzerland, as far as I know > >doesn't have them enabled on all the lines by default. > > > >Best regards, Rene > > > >---------- > >From: [email protected] on behalf of Duane J Marcroft > >Sent: Tuesday, March 25, 1997 3:31 AM > >To: [email protected] > >Cc: [email protected] > >Subject: Re: Filter for Germany > > > >Ben, > > > >I have designed a number of PCMCIA cards in the last several years and > >none them have billing tone filters for Germany. I believe it is now > >possible to have a modem approved in Germany sans filters. The modem is > >now allowed to make some errors in the presence of metering tones, but it > >must not drop the line. Also, if you use the inductance of the > >transformer in the correct way it is possible to increase the Rockwell > >modem tolerance of metering tones beyond 0.7 vrms and in the majority of > >connections the modem will not hiccup. By adjusting modem firmware it is > >possible to bridge hiccup periods and not disconnect. > > > >Regards,................. > > >
