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Op 23-12-2010 16:35, Ron Stordahl N5IN schreef:
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<div style="font-family: times new roman,new york,times,serif;
font-size: 12pt;">Can someone estimate the length of a typical
compressed position packet such as most mobiles would be sending
exclusive of TXDelay and TXTail. It's the time between these
two elements that I need, in order to determine the significance
of adjusting TXDelay and TXTail. Typical default values are 300
ms and 50 ms. Adjustment of the later is usually not offered.
<br>
<br>
I get reliable operation of our area UIDIGI's with old Motorola
Micors at TXD of 100, but I am not sure of the impact upon
others users ability to decode, nor am I sure if the reduction
in congestion is all that significant.<br>
<br>
Ron, AE5E (ex N5IN)<br>
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According to the aprs specs the minimum packet length including
header etc. is 44 bytes add 1 byte for kenwoods you come to 45 bytes
from start flag to end flag so that would be 0.3 seconds or 300 ms
at 1200 baud minimum, you can see right away that txd matters a lot,
you will find if you use a modem with a fast soft dcd or hard dcd
rather then using radio squelsh it is posible to get even lower even
down to 30 ms on modern allmode radios but even 50 to 70 ms should
be posible on most mobile fm rigs providing the recieving radio runs
open squelsh<br>
<br>
Andre PE1RDW<br>
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