2012-06-21 APRS Setup and Operation

[michael]

This week's net will discuss the basic fundamentals and features of APRS and some options for using it. We'll discuss common hardware and software set-ups for APRS solutions and some basics about making your own connecting cables. A brief history of APRS and how it relates to Packet Radio will also be discussed. If you're currently using APRS in your off-road vehicle we'd like to hear your solution and how you've set it up.

[sdnative]

delete

[ldsnet]

I hope someone posts a "podcast" of this topic. It is one I am very interested in hearing, but I am still out of the country (last one posted is from Feb 2012).

[toms]

Eric - can you hit Palomar? IT gets linked up with IRLP for the net. 449.300 - 100

[DaveK]

I hope someone posts a "podcast" of this topic. It is one I am very interested in hearing, but I am still out of the country (last one posted is from Feb 2012).

We record almost all of the nets and make them available on the home page. If you have some specific questions or areas you want discussed, post them here and we will make sure they are addressed during the net.

[michael]

Several of the questions on last night's net about APRS centered around Garmin or other GPS units. Here is a wiring diagram for making a serial cable to connect your Garmin GPS to your APRS tracker (TNC).

The DB-9 serial plugs can be purchased at just about any electronics store (Radio Shack, Fry's, etc). The round plugs used by Garmin on their serial connectors can be purchased from several sources online, including Argent Data Systems and pfranc.com. If you want to buy the cable already assembled, pfranc.com has the prefabricated cable with the connectors you'll need on both ends.

[michael]

For those of you who missed last night's net discussion on APRS, here is a transcript of the broadcast.

[michael]

Sounds like an interesting topic. I would like to participate, but I moved and have a hard time hitting Keller (for now until the tower goes in )

I am using a Byonics TT4 connected to a Yaesu FT-1500M using the data jack. GPS is a garmin 60csx. The 1500 is a dedicated APRS rig and doubles an emergency backup 2m radio for the Yeasu 8800.

Your vehicle APRS setup is similar to mine. I use an Agrent Data Tracker2 connected to a Kenwood TM-271 and a Garmin 60Csx. The tracker is also connected via a null-modem serial cable to my navigation laptop PC, which runs OziExplorer. A friend and I developed a software interface for OziExplorer that displays the APRS stations on the Ozi moving map by either name or call sign. You can specify which stations you want to see to eliminate clutter in crowded areas. We developed it specifically for when we're exploring the desert with friends and for search and rescue applications. The laptop PC is handy to have in the system because it also allows remote control of other Tracker2 units and for monitoring messages, etc as they are decoded.

A nice feature of the Tracker2 (and the TT4 as I recall) is that you can use it as a digipeater, which helps out when tracking vehicles in a group if they become separated in canyons or get out of the VHF 'line of sight'. Each vehicle repeats the transmissions it hears so the signal almost always gets passed to everyone, even if they're hidden by terrain. We typically use some 2m frequency other than 144.390 (or sometimes even a UHF frequency) so we don't clutter up the APRS channel.

The TM-271 is a good choice for a backup radio because it is an exceptionally rugged and nicely heat-sinked radio, and therefore good for offroading. It also makes an excellent APRS radio because there are pads on the motherboard that allow easy installation of a data port. Most radios with data ports cost extra, but Kenwood used the same motherboard on the European model (which has the data port) but didn't connect the pads on the U.S. model. The nice thing about using a radio with a data port for APRS is that the radio can easily be used for voice without changing the cables. Initially, it takes about 20 min to solder the pads to a mini-din data cable but after that it is plug and play! Unfortunately, the TM-271 is no long sold. The TM-281 replaced the TM-271, and the newer radio does not have the pads on the motherboard If you see one at a swap meet, I recommend you grab it!

Like you, I justified the second 2m radio I'm using for APRS as an 'emergency backup'. Kept my personal financial manager (spouse) happy