[OZAPRS] BMARC Expedition to Poeppels Corner

Geoff geoff-lists at gatwards.org
Thu Aug 13 11:32:45 EST 2009


Thanks to everyone who has indicated their HF Gates will be available for us
on 40m for this trip :)

Here is an update on the setup that will be used for the APRS component.
It's VERY non-standard, so I want to make sure we've 'notified' everyone
about the strange things that could be seen on the network during this time.

The mobile trackers on VHF (non-hf equipped 4x4's and bikes) will be running
the following settings:
- SSID = -13  
- Beacon Interval = 5 minutes
- Path = WIDE1-1,WIDE2-1,xxx,GATE,WIDE2-1

The -13 indicates a non-standard usage (not purely VHF -9, not purely HF
Whilst in normal network coverage on 2m, the WIDE1-1,WIDE2-1 part of the
path will allow the existing network to be used, with everything else being
(xxx will only be known to those on the trip to avoid possible abuse of the

When beyond the exiting 2m coverage area, The mobile gateway that will be
travelling in one of the vehicles takes over.  It runs digi_ned, which is
configured to detect the presence of the 'xxx' digipeater in the path, and
chop off everything before it (preempting).  It will then substitute 'xxx'
with the gateway callsign (VK2US-13) and gate the beacon from the bike to HF
with the remaining path - i.e.  GATE,WIDE2-1

The original and re-generated beacons from the mobile will look like this
(taken from digi_ned log)

from:2 VK2XJG-7 > PPPPP0 via WIDE1-1 WIDE2-2 xxx GATE WIDE2-1 UIv PID=F0 19
'vX.l .[/>PORTABLE

to:1 VK2XJG-7 > PPPPP0 via VK2US-13* GATE WIDE2-1 UIv PID=F0 19 bytes
'vX.l .[/>PORTABLE

The mobile gateway will also have a 3G data connection, and can run as a
mobile IGate whilst in 3G coverage, so not all posits will be sent via HF,
especially if HF APRS interferes too much with the HF voice comms that will
be also running from many vehicles.

This setup will be tested in the next week or two 'for real' to make sure
these configs do actually allow posits to gate from vhf to hf and back into
the APRS-IS before the fella's head out west.

Geoff  VK2XJG

-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Geoff
Sent: Saturday, August 01, 2009 5:30 PM
To: 'Australian APRS Users'
Subject: [OZAPRS] BMARC Expedition to Poeppels Corner



The planned Expedition by several Blue Mountains ARC members to Poeppels
Corner is coming up fast - the group leave Sydney on 29 August for a 15 day
trip out to the corner of VK4, VK5 and VK8.  


There will be a convoy of 4x4's and motorbikes, a few of which will be
carrying APRS trackers.  Whilst some of the 4x4's will have HF APRS
capability, most of the trackers will be 2m VHF units - especially the


For this trip, a special non-standard setup has been put together,
consisting of a "Reverse HF Gate come IGate".

This system is a laptop running Linux, with both digi_ned and javAPRSSrvr
configured, to gate the 2m posits to the Internet when within mobile 3G Data
coverage, or to HF when beyond the range of the mobile phone network.  The
Reverse HF Gate will only accept a special digi alias, so it will not
inadvertently gate everyone to HF if the convoy travels through an existing
VHF coverage area.


We will be configuring the trackers with HF parameters, so the beacon
intervals will be at 5-10 minutes, however to identify these "special"
stations, an SSID of -13 will be used.  (The standard HF mobiles will still
use -15 and regular paths).


The group are planning to use 40m for this trip, to allow all trackers to
operate under their own callsigns.

Could I please have a show of hands as to who would be able to operate their
HF Gates on 40m for the period 29/8 to 12/9 to help support this trip ?


More information about the trip can be found on the club's website -



Geoff  VK2XJG

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