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<div class="moz-cite-prefix">On 27/05/13 3:34 AM, Bear Albrecht
wrote:<br>
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<blockquote cite="mid:51A247B7.8000702@gmail.com" type="cite">
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<div class="moz-cite-prefix">On 5/26/13 11:10 AM, Brad NK8J wrote:<br>
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<blockquote cite="mid:001801ce5a33$f1fc7890$d5f569b0$@juno.com"
type="cite">
<pre wrap="">Most Fire Stations and ambulances require DTMF Tones to tell them which
station is being sent out to where. </pre>
</blockquote>
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. <a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://www.batlabs.com/qcii.html">http://www.batlabs.com/qcii.html</a>
has some of the info although it doesn't cover what we use, nor
several other variants.<br>
</blockquote>
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.<br>
<br>
<pre class="moz-signature" cols="72">--
73 de Tony VK3JED
<a class="moz-txt-link-freetext" href="http://vkradio.com">http://vkradio.com</a></pre>
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