[aprssig] Amount of "padding" before and after data at 1200 baud?

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Fri Jul 21 12:14:42 CDT 2017


And tuning for the minimum that works in your neighborhood might not 
work in other areas depending on their particular RF infrastructure.  
IMHO, longer that works everywhere is better than tightly short that 
barely works in your local area and completely leaves you non-decodable 
elsewhere.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 7/21/2017 1:09 PM, Scott Miller wrote:
> The preamble length also depends on how fast the receiver locks on and 
> how fast the receiving modem gets clock sync.  I'd say 100 ms would be 
> a minimum for normal APRS use, and I think my trackers default to 200 ms.
>
> Scott
> N1VG
>
> On 7/21/2017 8:44 AM, Alan wrote:
>> In adjusting the TXDelay and TXTail parameters, is there a 
>> recommended number of ms before and after the data that you want 
>> actually transmitted?  With conventional rigs, it is relatively 
>> simple to take a guess, and tweak it slightly until it is reliable.
>>
>> In working with DSP rigs, not only is the internal latency 
>> significant, but in some cases not entirely reproducible.  That is, 
>> you can send a series of beacons, and the timing will vary from one 
>> to the next.  I can look at the actual output, and would like to know 
>> what the minimum recommended times are so that I can insure that 
>> without just brute forcing long unneeded transmission times.
>>
>> 73s,
>>
>> Alan
>> WA4SCA
>>
>>
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