[OZAPRS] HF Tracker beacons and Compressed frames

[Richard Hoskin]

Hi Tony,

Thanks for the good information and comments. It applies equally to HF and
VHF.

The only time compression can be a problem is when 'UI-View' Compression
is
used for WX Stations, the D7/D700 will not decode these WX packets.

Note that the compression used in UI-View is different to MIC-E.
Information
on both can be found in the APRS Specs.

Cheers
Richard
VK3JFK


> -----Original Message-----
> From: ozaprs-bounces at marconi.ics.mq.edu.au [mailto:ozaprs-
> bounces at marconi.ics.mq.edu.au] On Behalf Of Tony Hunt
> Sent: Tuesday, 28 September 2004 9:09 AM
> To: OZ-APRS Mial-list
> Subject: [OZAPRS] HF Tracker beacons and Compressed frames
> 
> Its interesting and good  to note a few more HF users appearing.. Ive
also
> noticed that there are some using uncompressed frames.. Now there are a
> few
> possible reasons why this is happening but it would seem sensible to
make
> comment about our settings particularly on Tiny Traks..
> 
> For those running Tiny Traks on HF you can do yourselves a real favor
and
> change the settings to Enable the MIC-E format. Sending uncompressed
> frames
> seems to produce a packet of about 96 bytes. Sending MiC-E results in a
> frame of 13 bytes.. Not just a good saving on channel bandwidth but an
> appreciably higher chance in actually getting a valid frame to propagate
> and
> decode on HF especially when its noisy or when its just poor propagation
> at
> the time..  There are all sorts of settings on Tiny Traks particularly
the
> version 3 but
> this one setting is probably one of the more important ones (in my
> opinion)
> that makes
> a real difference and also makes your efforts worth while by making it
> work
> effectivly.
> 
> Ive messed about alot of late on HF with messaging frames which are
> typically 80-90 byte frames.. Sending these and getting them to decode
is
> a
> challenge on HF at times.. Getting the ACKs back is far easier generally
> being 13-14 bytes..
> 
> So even on 2m channels this same philosopy applies.. A NMEA string I
just
> saw for a mobile in VK3 was 116 Bytes whereas a compressed MIC-E frame
> would
> convey the same general info very quickly and more reliably.
> 
> UI-View also if used in a mobile as a traking device should be set to
use
> Compressed frames. There are still some devices about that cant send
> compressed frames like KPC3 and TNC based trackers.. While there is no
> harm
> in using these it begs the question why on earth not turn on compression
> if
> its available??
> 
> Tony Hunt VK5AH
> 
> 
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