[OZAPRS] HF APRS is different, Really different to VHF APRS

[Brian Beamish]

Hi
 
Before I start I am not a new on the block "Whiz Kid" with all the
technical know how and jargon I came up the hard way starting with
absolutely no electronic knowledge having to study and sit for essay type
exams and 10wpm CW.
 
I must add here that I am also 100% for the dropping of CW and other
licence changes anything that encourages and brings new blood into our
hobby I am 100% for it.
 
I got into the "Digital Modes" way back in the 70s starting by
rebroadcasting the WIA and VK4 News on RTTY firstly typing in on to paper
tape and transmitting on HF with the use of a Model 15 teleprinter, I
progressed from there still on RTTY to a Commodore 16k Pet I actually used
to connect to the ARRL in USA with the Commodore Pet with the grand speed
of a 300 baud  via a acoustic coupled modem over the phone to get snippets
of news not available here.
 
Satellites and Packet for me came along about the same time and I grabbed
them with open arms ending up running the VK4BBS Packet BBS station for
some 13 years, this station still runs under the VK4WIE callsign looked
after now by the City of Brisbane Radio Society SysOp Ari VK4PKT, to this
I added the first HF Packet gateway out of VK to USA and also into Asia
(AsiaNet) along came the digital satellites and I added the first VK
Satellite gateway HF packet went to PSK but slowly disappeared and about
the time that I passed the BBS over to the CBRS satellite gateways were on
the way out and Wormholes were on the way in.
 
Why tell you all this really only to let you know that whilst not so much
on the technical side I have had considerable experience on the
operational side of RF digital communications during this time I have made
many errors in fact it all has been " flying from the seat of my pants"
all trial and error but what an exciting and fun time have I had doing
just that and what a thrill it was when things all panned out and worked
correctly but is sure was not without a lot of trial and error, APRS has
been the same.
 
HF Packet is different, Really different to VHF APRS.
 
With the changes in licensing about to take place and reading the grape
vine I imagine that there are those, hope they do, currently on VHF APRS
who will hopefully want to give HF APRS a go. Whilst I personally look
forward to seeing you there in the near future I should make you aware the
HF APRS is vastly different to VHF.
 
Looking at your map and seeing stations move about I doubt if you will
really recognise these differences for after all for a station Monitoring
on HF, VHF or via an Internet Gateway the results are virtually the same
but actually operating is vastly different.
 
1. On HF a beacon at either 15 or 30 minute intervals is all your will
hear of a HF APRS Gateway.
2. The HF Gateway does NOT digipeat on HF it may though do so on either or
both VHF or an Internet Gateway.
3. HF gateways gate traffic to VHF and internet but there should NOT be
traffic the other way round, ie VHF and internet to HF.
4. You can NOT connect to a HF Gateway whilst some VHF gateways allow
this.
5. Your beacon should NOT contain Speed and Height etc just the very basic
location no more.
6. You do NOT use 1200 baud on HF your use the slower 300 baud.
7. Your beacon should NOT be long, mine at 21 character takes almost 4
seconds to transmit when more stations get on I will reduce this even
further but it still will be around 3 seconds, bonuses of having a shorter
beacons on HF include having a far better chance of being heard error
free, it is only the error free beacons heard and passed on by the HF
gateway, and allows more stations to operate on HF at a similar time.
8. You can NOT ping, query, send messages or chat etc on HF you must go to
VHF or Internet to do this.
9. You generally can NOT track other stations, unless heard direct by you,
on HF again you should  go to VHF etc to do so.
10. Try to NOT interfere other HF APRS stations with your beacons which is
hard due to HF Skip as you may not hear them..
11. You should NOT send Objects or the like on HF go to VHF or the net if
you must send objects NOT HF.
12. You MUST Net with a HF Gateway like VK3SB or VK4DMI if you don't you
will just NOT get heard.
13. Please use the recommend path of only GATE,WIDE when on HF especially
if you want to remain friends with the HF SysOps.
14. Above all you should think of others particularly on HF for if you
thought VHF a challenge you have NOT tried HF yet.
15. You do NOT really need a TNC for HF APRS just a tracking module like a
TigerTrak is all that is required.
 
Give HF APRS a try really needs a few more there and certainly another two
or three suitably place HF Gateways around VK/ZL would be most welcome,
look forward to hearing your beacons there.
 
Hope that the above gives some food for thought to those contemplating
operating on HF APRS.
 
B C N U
Brian VK4BBS
Brisbane.
 
Yes this is an plug for I like VK4DMI are very happy with our APRS, SSTV
and GPS product and service of Tigertronics it is worth having a look
there http://www.tigertronics.com/ especially whilst the Aussie Dollar is
so good.
 
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