[chirp_users] Fire paging

[Tony Langdon]

On 27/05/13 3:34 AM, Bear Albrecht wrote:
> On 5/26/13 11:10 AM, Brad NK8J wrote:
>> Most Fire Stations and ambulances require DTMF Tones to tell them which
>> station is being sent out to where.
> Well, not exactly.  The system here is "two-tone" which has one single 
> tone transmitted for a couple of seconds and then another single tone 
> for a couple of seconds.  Precise timing I can look up on Tuesday if 
> needed.  Google "two tone paging" for some of the angles. 
> http://www.batlabs.com/qcii.html has some of the info although it 
> doesn't cover what we use, nor several other variants.
We used to use that here in the late 1980s.  I was toying with the idea 
of building a decoder (before software methods were practical) when we 
had the system installed.  I got good at picking the tones by ear in the 
end, could tell ours from others in use.  Those days are long gone, as 
we now use a statewide single frequency POCSAG network, independent of 
the voice channels for emergency callouts.

-- 
73 de Tony VK3JED
http://vkradio.com

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