First real qso via GO-32…

November 20, 2007 | Amateur Radio | By: Mark VandeWettering

I was experimenting with APRS messaging via GO-32 this morning, after being simply overrun by Mexican hams earlier in the morning on AO-51. W7KKE runs a GO-32 SatGate in Lincoln City, Oregon (a place I’ve visited many times) and was apparently listening when I messaged him this morning via my TH-D7. I wasn’t using a computer, so it was rather like text messaging from a cheap phone, but here are the messages as recorded in my HT.

AMSG 3,W7KKE-1,73s,I
AMSG *,W7KKE-1,handheld here,H
AMSG M,W7KKE-1,Good to see some GO-32 activity!,51
AMSG 1,W7KKE-1,first qso on go32,G
AMSG M,W7KKE-1,Good morning!,50
AMSG *,W7KKE-1,hi ken,F
AMSG 0,VA3SU-1,test,E
AMSG B,4XTECH-12,D7&D700 posits use 145.9s,3
AMSG B,4XTECH-12,APRS msgs and clients use 145.85 Upl,2
AMSG B,4XTECH-12,su APRS!!Use pth via 4XTECH,1
AMSG 0,VA3SU-1,hi there ,D

Addendum: Using the information from here, it appears that the first number after the AMSG statement is either an M (indicating that the message is Mine), a B (bulletin), an asterisk (meaning the transmission was acknowledged) or a number (indicating the number of times that it will retry to send it). You can see that my attempt to reach VA3SU was unsuccessful, but that W7KKE acked a couple of my packets.


Comment from Dan Lyke
Time 11/20/2007 at 4:22 pm

Charlene and I just got our Technician licenses, but the process was such that we know the answers to the test questions rather than actually understanding anything.

Any suggestions for places to begin learning? Our primary concern was emergency services during the Marin Century, and probably participating in some of the disaster preparedness drills. I know that the HAM club that supports us has some sort of APRS system on various support vehicles because they’ve got a projector with SAG car locations on it back at the comm center, but as I read through your notes and other things I feel like I’m just picking up narrow views into something that an overview will make clear.

Comment from Mark VandeWettering
Time 11/20/2007 at 7:20 pm

I must say that’s pretty precisely the problem that I’ve found with the many online websites that talk about this stuff. A lot of the information is spread out, out of date, insufficiently detailed, or too specific to get a really get overview of what’s current best operating procedures and process.

APRS is a pretty simple thing actually. Packet radio (which except for APRS seems extinct) is based upon the AX.25 protocol. AX.25 supports reliable connections much like TCP/IP, but also supports unreliable, packet oriented communications, similar to UDP. APRS uses this, with an adhoc distribution scheme to distribute position reports. There also exist gateways which transfer these reports onto the Internet, via something called APRS-IS. It’s actually pretty easy to use any standard packet controller (or TNC) to send APRS packets. They are basically just UI packets (I forget what UI stands for) with particular kinds of routing and information stored within. They are repeated by “digipeaters” out to some radius, then they die. In the US, 144.390Mhz is the standard frequency for APRS, and you can hear the “blaaaat” sound of the packets pretty much everywhere.

The ARRL has some pretty good introductory articles here that describe what’s possible. APRS can be used to distribute weather information, to transmit telemetry from aircraft or balloons, or to coordinate movement of emergency services. Kind of neat actually.

The particular HT I have has a built in TNC, so you can do packet right out of the box. It has ports that allow you to plug in a GPS and hook it to a computer, so it is really quite versatile, and can do many APRS functions without any additional help from a PC. In use, it beeps whenever you get a new position fix broadcast, and can tell you the bearing, direct and speed of these sites. You can also receive APRS messages, and even sending them, although it’s rather like text messaging on a bad cell phone.

If you are interested in just a cheap tracker (perhaps for a tandem bicycle? 🙂 ) to put on a vehicle, you can look at something like the tiny tracker which is a transmit only solution.

Comment from Dan Lyke
Time 11/21/2007 at 2:03 pm

Thanks. I think I’ve run across a few folks using the term APRS to refer to packet radio, or maybe it’s just that I’ve been seeing “APRS capable”.

I think we need to go to some local club meetings to absorb some of the lore.