[aprssig] Fwd: [nwaprssig] BALDI/VBALDI igate functionality

David Dobbins ddobbins at gmail.com
Mon Dec 13 02:07:24 CST 2010

FYI from the NWAPRS mail list. Digipeaters mentioned below are in the
Seattle/Puget Sound area. Dave K7GPS


BALDI/VBALDI has had some interesting improvements in the last month or so.
Scott N7FSP and I added an additional piece of hardware to his APRS station
up on the hill before the snow and we now have added IGate functionality for
both 144.39/1200 and 144.35/9600.

The hardware is a Lantronix UDS2100, a commercial-grade dual-port
serial-to-ethernet converter.  It's a small box about the size of 2 packs of
cigarettes.  The device is physically connected to the serial port of the
OT2 TNC on the .39 side and the serial port on the D700 TNC for the .35
side.   The Ethernet side of the device is connected to the Internet through
a router at the site.  At my QTH I have a server that runs the WW7CH
IGate/WX station and is also running a piece of relatively new Linux-based
digi/igate software called aprx <http://wiki.ham.fi/Aprx.en>.  aprx connects
to the APRS-IS, and also connects to the remote TNCs on the hill via
internet tcp stream and operates them in KISS mode (KISS over IP, or
KoIP!).  Prior to running aprx I tried running UI-View and connecting to the
TNC via serial port emulation software, tried APRSISCE, and aprsd as well.
All three worked, but aprx had the most functionality for what I wanted it
to do and was designed for this kind of application, including the ability
to do all of this with 1 instance of software running with no memory
leakage.  And it's open source!

The advantage to using a serial-ethernet converter over having a PC at the
site is because the site is not easily accessible almost 6 months out of the
year and the Lantronix device is a firmware-based appliance specifically
designed for this type of application that is far less likely to fail than a
PC.  The ISP that provides the network connectivity at Baldi responds VERY
fast to outages there year-round because that is lost revenue to them when
it goes down.  So it's comforting to know there's good reliability there.

I have been experimenting with this setup for over a month now (including
experimentation with cross-freq messaging and digipeating) and neither Scott
or I have received any complaints about its operation.  In fact it has
resulted in quite a few more packets being heard direct making it into the
APRS-IS and increasing the chances of messages/acks being heard in the
field.  Since it can hear many packets first before they are first digi'd,
it results in less packets being lost due to RF collisions, which is
frequent on .39.  No, it doesn't solve the congestion issue, but it does
help to allow for the packets that would have otherwise been lost to get
into the system.

One feature of aprx is the ability to send telemetry to the APRS-IS to show
erlang and RF packet count statistics:
BALDI (1200 side) - http://aprs.fi/telemetry/a/BALDI
VBALDI (9600 side) - http://aprs.fi/telemetry/a/VBALDI

The amount of packets sent/rcvd to/from the APRS-IS is shown on Tom KD7LXL's
server statistics page (connected as BALDIMTN):

This station and setup does not replace any existing igates/digipeaters nor
make any others obsolete - that's not the intent.  Like any other station,
it is always subject to outages due to internet connectivity loss, power
loss at either end, etc. and will occasionally miss packets here and there
due to collisions, etc.  The intent is to enhance APRS coverage/capabilities
in the area by taking advantage of having internet access on the mountaintop
and Scott, me, and others are noticing that it is working successfully.

Casey WW7CH
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