[OZAPRS] FW: Dos & Don'ts for APRS HF (A Guide)

[Ron and Val Smith]

Hi Richard,
I think we need to think in terms of geography and not just states.
For example I am about as far from Des as Des is from you but I am less
than half way across Queensland.
I would like us to think of other scenarios applicable to situations
without significant vhf coverage. I know the network in Vic is excellent
but it is almost non-existent in Qld outside Brisbane.  There is a good
case to look at 40m to cover close range scenarios in addition to 30m.
As I think most know I am looking at digi sites around here in Central
Qld.  Most hilltops are inaccessible and those that have tracks need four
wheel drive high clearance vehicles and do not have mains electricity.
Another complication is that the most likely emergency situation in Qld is
storm or cyclone with flooding so remote sites are likely to be the wrong
side of flooded creeks. So emergency response situations, eg WICEN
activities, cannot be implemented rapidly on VHF unless the infrastructure
exists and has survived the storm.  So short range hf needs to be
considered.
Cheers
Ron
vk4ags

----- Original Message -----
From: Richard Hoskin <mailto:vk3jfk at amsat.org>
To: ozaprs at marconi.ics.mq.edu.au ; zlaprs at mail.nzart.org.nz
Sent: Monday, 24 May 2004 21:29 PM
Subject: [OZAPRS] FW: Dos & Don'ts for APRS HF (A Guide)




Hi All,



I’ve been working on an APRS HF Guide to assist operators.

The guide below is currently in a draft format where any ‘?’ are yet to be
determined.



I would like to receive comments / suggestions to be included in the final
version of the Australasian APRS HF Operations Guide.



Remember that HF APRS is completely different to VHF APRS so please think
of the larger Regional picture which involves Australia, New Zealand, Papa
New Guinea, New Caledonia etc.



Once this is finalised I will add it to the HF web page I am putting
together.





--------------------------------------------------------------------------
---

Australasian APRS HF Operations Guide.





As HF APRS is becoming more popular in Australasia I have put together a
set of guild lines that we all need to adhere to. This will allow the
successful long-term use of the ARPS HF 10Mhz network as it’s popularity
continues to grow.



The Do’s and Don’ts for APRS HF.



Do’s



1.	Do consider all other users of the HF network. Remember you are
sharing this single frequency with hundreds of other operators.

2.	Do use only a path of GATE,WIDE

3.	Do Net (set your frequency) to the Primary Net server VK3MY-4. Or
if you can not here VK3MY-4 use a secondary APRS HF Gate server.

4.	Do user a SSID of  -4 if your station is an HF to VHF (or IS)
Gate. (Refer to the SSID Guide)

5.	Do keep your packet size to a minimum. Use the Mic-e or APRS
compressed format and no or minimal information in your status text.

6.	Do set your beacon time to 10 minutes or more. ( The primary and
secondary net stations are the Only station that will  beacon at more
frequent intervals)

7.	Do use the path of ECHO Only for tuning your radio into the Net.

8.	Do use the following TNC settings for your success. TXDelay 400ms,
PACket LENgth 64, SLOTtime 300ms PERsistance 64ms.

9.	?



Don’ts



1.	Don’t Digipeat any packets on HF (the only exception is for tuning
your radio).

2.	Don’t transmit Home station positions on HF. Only Gates and Mobile
stations need to transmit position information.

3.	Don’t feed VHF or IGate data to HF

4.	Don’t allow your station to operate as a digipeater

5.	?



APRS HF NET Servers.



Primary NET server – VK3MY-4

Secondary Net servers – VK4DMI-1, VK6???, VK8??? ZL?????



The Primary Net server will transmit the following messages at the
indicated times:



Every 5 Minutes - / APRS 10Mhz Net Station (1)

Every 10 Minutes - APRS HF To VHF Gateway On 10.147.60Mhz USB



The Secondary Net servers will transmit similar messages at 5 minute
intervals.

Eg;  APRS 10Mhz Net Station (2)





APRS HF Gates;



VK3MY-4, VK3ECV,VK4DMI-1, VK6???, VK8??? ZL?????





NOTES:

Remember that an average length APRS Posit packet takes 3 to 4 seconds to
transmit on HF. Assuming a channel efficiency of 30% for ax25 this results
in a maximum of 7 stations being able to transmit per minute. At a
transmission rate of one posit per 10 minutes the maximum number of
stations that can be in a single APRS Gate’s coverage area is 70 stations.
This will be less as the Net stations transmit frequently and messages
and/or tuning may be under way on the channel. HF Propagation is also an
important factor in limiting station numbers.



--------------------------------------------------------------------------
----------------------------------



Regards

Richard

VK3JFK



  _____




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