[aprssig] Roundthe-world approaching Cancouver Island now!

Steve steve at daniels270.eclipse.co.uk
Wed Jul 23 18:46:00 CDT 2014


The tracker sends it's current location as normal, but also in the comment
field attempts to send the last 64 locations taken every 2 hours, which is
around 5 days. For the time it is out of range of any receiving stations.
It's in Base91

Steve
G6UIM

-----Original Message-----
From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf
Of John Langner WB2OSZ
Sent: 24 July 2014 00:38
To: aprssig at tapr.org
Subject: Re: [aprssig] Roundthe-world approaching Cancouver Island now!


The telemetry format is a little perplexing.

After discovering http://he.fi/doc/aprs-base91-comment-telemetry.txt, we can
understand this:

M0XER-3>APRS63,WIDE2*,qAR,VE7VMH:!//xOy0<xtO JioE/A=041397|y6OV&s<W!,|

The part between the | characters, in the comment field, is the base 91
representation of the telemetry values.

The protocol spec indicates that we still need the original special
"message" packets for the metadata such as field names, scaling
coefficients, and units.  I don't see them anywhere.

However we do see less frequent longer packets like this:

M0XER-3>APRS63,WIDE2*,qAR,VE7VMH:!//w{W0=T:O
Jiq1.tJ57Q+UnByC(\Gb:$Yw>z/A=041420|y9OR&\<[!)|

What does ".tJ57Q+UnByC(\Gb:$Yw>z" represent?   Is this the metadata in some
new compressed format?  Where is it documented?

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