APRS Notes

The Least Expensive Setup

• The Radio

• K2 to TRSS cable

  With a TNC

• Add a Bluetooth TNC

• Use a Raspberry pi TNC

  Future APRS Mobile

APRS stands for Automated Packet Reporting System. A packet(AX.25 format) is sent from your radio’s Terminal Node Controller(TNC), or an external TNC, and received by other receivers in the area.

The US 2-meter frequency is 144.390.

Generally the APRS packet contains Location information, weather conditions, or current Voice Frequency.

The packets can be received by an iGate, which may report the packets to various aprs websites. The one I use is https://aprs.fi

The Least Expensive Setup

An inexpensive radio($25-40) coupled to a smartphone via an inexpensive cable($20). And I believe the APRSdroid software is free or only a few dollars in the google play store.

The radio

One radio that I use regularly is the Baofeng BF-F8+

Be sure to pick up the Baofeng Programming cable, it works great with the BF-F8+ or UV-5R. It’s certainly not necessary, but makes programming the radio with CHIRP much easier..

Anybody that poo-poo’s these Either

• A: does not know what they are talking about
• B: is probably a radio snob
• C: Some combination of A and B and has a lot of money to spend.

They work fine and in some cases better than other devices you could buy for quadruple the cost.

Some extra handy doo-dads

• SMA to BNC
• Diamond RHF40 - works really well and folds up in my pack.
• BNC to SO239 - quick connect for the SMAtoBNC for a standard antenna.
• Bigger battery
• 8-watt BaoFeng BF-F8HP radio - Mine puts out only 4-watts

K2 to TRRS cable

The K2 to TRRS cable works great with the Baofeng and APRSdroid.

A few notes:

• Squelch must be set to at least 1 to use the VOX;
• the VOX on the radio was fine at 1;
• The volume nob’s marking has the fattest part pointing at the LED(About 1/2 volume).

With TNC

The TNC is nice because it takes the signal processing away from your phone/tablet device so you can have notifications and stuff running on your phone.

Add a Bluetooth TNC

I’m using the Baofeng with the Mobilinkd TNC1 (There is also a new version TNC2)

Use a Raspberry pi TNC

The TNC-pi plugs in to your radio via a serial cable and is a hat for the raspberry pi.

I’ve had the TNC-pi around since I got my tech license… but I haven’t set it up yet. Arg. One of these days.

Future APRS mobile

Not an inexpensive setup - A nice radio for the vehicle

Looking into getting the Yaesu FT400DR for my vehicle. It seems to do great with beaconing APRS and Displaying received APRS.

The important part, for me, on this radio was the ability to scan Frequencies for voice, while sending and receiving APRS beacons.

To integrate with a phone or computer there are cables that plug into the back of the unit. As a mobile unit, I can’t think of a reason to do this unless you want to send messages instead of the preprogrammed APRS macros.