At 02:44 PM 12/21/04, you wrote: >I know a repeater that required a tone not implemented in the standard >38 would not make a it too popular but is it legal? I was wondering if >a pair of these on a rcv link would discorage interference. > >http://www.com-spec.com/ts64.htm
There is no FCC rule specifying subaudible tones. Local coordination councils have been known to specify tones, usually what tone you can not use (i.e. the system 50 miles away on the same channel uses 100hz, they would appreciate it if you don't use 100hz). Nonstandard tones have been around since the late 1950s. I found 159.0 Hz reeds in a pair of HT-220s in the 1970s, and 121.1hz PL reeds in a pair of handhelds that came back from a job in Buenos Aires in the 1980s.... However, tones inbetween two standard tones are to be avoided due to false decodes... your inbetween tone can false two standard decoders, and either of the two tones that you are between can false you (there is a reason that there are 32 standard tones between 67hz and 204hz and not 35 or 40 - it's called separation between tones to minimize falsing). I commented on nonstandard tones for privacy in my writeup on the Mitrek reedless PL board, which is at <http://www.repeater-builder.com/mitrek/mitrek-hln4181.html>. >One advantage to the HLN4181 - you can have a Mitrek on each >end with NO tone element installed (i.e. set to 273.3hz) and they >can talk to each other. The higher frequency tone also means >minimum pickup delay. This is ideal on point-to-point links (and >it saves having to make up any elements). Yes, the 273.3hz >tone is harder to filter out than a lower frequency but it can be >done with an active filter. > >The HLN-4181 PL board also allows you to pick weird or non- >standard tones in 0.3hz steps from 273.3 on down, but to make >them workable you need these PL boards on both ends... this >trick can be handy on point-to-point links that you want to keep >the riff-raff out of (if you don't mind the PL pick-up delay). Maybe >199.2 hz anybody? Or 235.0 hz? However, you have to >remember that PL (or Digital PL) doesn't solve interference >issues, it just covers them up. Sure, the RX won't unsquelch >if it is requiring a weird tone and the idiot only has the standard >tones but the idiot can still sit there and transmit on the channel >causing a heterodyne or capturing / blocking the receiver, so >what real security (or increase in usability) have you really gained? >And what prevents a determined idiot from listening to you on the >input with an OptoElectronics tone grabber and finding your weird >magic tone ? (it only takes maybe 5 seconds of signal). And a used HLN4181 is around $20, a lot cheaper than a TS-64. Mike WA6ILQ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
