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[aprssig] Voice Alert in Europe (T136)

Cap Pennell cap at cruzio.com
Fri Jun 4 02:22:08 UTC 2010

Please, all, don't forget to update/edit our international APRS wiki too.


73, Cap KE6AFE

> -----Original Message-----
> From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On
> Behalf Of Robert Bruninga
> Sent: Thursday, June 03, 2010 6:35 AM
> To: 'TAPR APRS Mailing List'
> Cc: aprs at yahoogroups.com
> Subject: [aprssig] Voice Alert in Europe (T136)
> Seeing several references to:
> >> Europe, Finland, Ireland: 144.800 MHz Voice Alert = 136.5 Hz.
> >> While we've adopted 136.5 here in Ireland...
> Yes, 100 Hz was fine for the USA with a 60 Hz grid and 60 Hz TV
> scan rate, but in some countries in Europe, harmonics of 50 Hz
> power grid and mrgawatts of 50 Hz PAL TV RF would give false
> squelch openings on 100 Hz.
> So for Europe, Voice Alert is 136.5 Hz CTCSS.
> We need to make sure that all documents reflect this.
> I just went through and corrected my web page
> http://aprs.org/VoiceAlert3.html
> And I invite everyone to update theirs as well.  It will take me
> time to correct all of my other documents, but I will.  If
> anyone disagrees that T136 is NOT the standard European Voice
> Alert, lets battle it out now or forever hold your peace.
> Further, Notice that in APRS we refer to tones by their
> whole-number values and ignore the decimal point.  All tones
> these days are generated by special chips and so we only use
> their frequency as a reference, not as an exact need to specify
> the exact frquency.  No one gives a hoot whether it is 136.5 or
> just T136.  They dial in whatever their radio has in that slot.
> That is why APRS has standardized on the 4 byte format of "Tnnn"
> for specifying PL or CTCSS tones instead of CTCSS 136.5 which
> takes almost 3 times as much bandwidth!
> Bob, Wb4APR

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