schatz@cs.arizona.edu (Bruce Schatz) (07/10/90)
I have a T1000SE laptop with the built-in 2400 baud modem sold directly by Toshiba. Often when dialing, I find I can hear radio music in addition to the dialing tones. This radio interference stops after the modem CONNECTS but then causes considerable noise on the line (random characters appearing on the screen though not interpreted). I live in a house and the immediate neighbors are not likely to be playing a radio. Has anyone else experienced this difficulty and if so are there known solutions? Thanks.
jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) (07/10/90)
In an article schatz@cs.arizona.edu (Bruce Schatz) wrote: >I have a T1000SE laptop with the built-in 2400 baud modem sold directly >by Toshiba. Often when dialing, I find I can hear radio music in addition >to the dialing tones. This radio interference stops after the modem CONNECTS >but then causes considerable noise on the line (random characters appearing >on the screen though not interpreted). I live in a house and the immediate >neighbors are not likely to be playing a radio. Has anyone else experienced >this difficulty and if so are there known solutions? Thanks. Are you located near an am radio transmitter? The music you hear is being picked up by the phone line acting as an antenna. This sometimes can happen at a long distance, though usually within a mile or so of the tranmitter. (KFI in L.A. can sometimes be heard on telephones 40 miles away!). I don't know what can be done about this. It partly depends on whether the detection of the rf signals converting them into audio is occurring within the modem or elsewhere in the phone line. I have never heard of a commercially available rfi filter for phone lines, but this is the sort of thing that ham radio operators fiddle around with all the time. -- John Dudeck "I always ask them, How well do jdudeck@Polyslo.CalPoly.Edu you want it tested?" ESL: 62013975 Tel: 805-545-9549 -- D. Stearns
jamesb@bushido.uucp (Jim Harvey) (07/13/90)
Re: Radio Interference in the Toshiba Modem I have used the Z100 RF supressor available at AT&T phone centers with good results. They are expensive >$15 so you might want to live with the noise if it is not that bad. This type of interference is usually caused by RF conducted into the modem on the phone wiring being rectified by the diodes in the ringing detector. A small capacitor (0.01 microfarad) across the line may be all that is necessary. -- ------- Jim Harvey | Michigan Bell Telephone Co. | "Ask not for whom the bell tolls and you 29777 Telegraph Rm 3352 | will only pay station to station rates."