[aprssig] What sets the max packet length for APRS

Bryan Hoyer bhhoyer at gmail.com
Sun Dec 2 12:09:50 EST 2012

Thanks for clearing this up.

How do I reserve APNxxx or APUxxx for NW Digital Radios? i looked in APRS101 and see it isn't currently in use.


On Nov 10, 2012, at 4:21 PM, Robert Bruninga <bruninga at usna.edu> wrote:

> The original texting APRS radio, the D7 can only display 45 bytes of Messages.  The D700 displays 64.
> The VX8R etc I think displays 80 maybe.
> Just remember, limiting to 45 charageceters will ALWAYS work and be seen by everyone.  Anything longer is risking miss-commmunication. 
> But yes, they can be longer if you KNOW who you are sending to.  That is why the APxxxx identifies the type of radio in all packets, so we can see what their capabilities are.
> Bob, WB4APR
> From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf Of Bryan Hoyer
> Sent: Saturday, November 10, 2012 11:22 AM
> To: TAPR APRS Mailing List
> Subject: [aprssig] What sets the max packet length for APRS
> APRS1.01 states 67 characters for a message and up to 43 for a comment, yet I see packets twice that long on APRS.FI. This ones 109 after the :
> KA8OAD-1>APU25N,K8YSE-1,WIDE1,K8UI-1,WIDE2*,qAR,K8LI-1:@101613z4108.09N/08136.25W_190/004g005t057r000p020P020b10220h51FWX_http://pages.sssnet.com/kend Fairlawn,OH
> AX.25 says 256 bytes for the UI payload
> A Tweet is 140 characters
> An SMS is 160 characters
> Is it just the display limit of some radios?
> Just exploring the capabilities and limitations of APRS
> Thanks!
> Bryan Hoyer - K7UDR
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