[aprssig] Deviation

Steve Bunting stephen.bunting at virgin.net
Tue Mar 16 10:53:57 EDT 2010

I have old school packet question for you all from someone who is still

In an attempt to be a good citizen, I have picked up a deviation meter 
and am going round tweaking various trackers and digis that I use or am 
responsible for rather than using the traditional “by ear” method.

I have several TNCs and radio combinations in use but there is always a 
difference in the low and high tone deviation, e.g. when my OT1+ has a 
high tone deviation of 2.4KHz, the low tone is only at 1.5Khz. I 
understand that this is normal and why 
(http://www.febo.com/packet/layer-one/transmit.html ) but my question is 
what do I set the deviation at for the high and/or low tone at for a 
12.5KHz channel? I asked this question on the UKAPRS forum and got 
several different answers (ranging from 0,9 to 2.4KHz). Whilst I 
appreciate the time that has been put into providing these replies, I am 
not much further towards knowing which is right so am asking a larger 

I am not trying to start a fight, I just want to understand!

Thanks in advance for your help es 73
Steve M0BPQ

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