Archive for APRS

My APRS setup

Yaesu FT-7800, Kenwood TW-4100E and Raspberry Pi 3

It’s about time I write some more here, the updates have been seriously lacking for a few years 🙁


I have a link to this website in the status text for my digipeater, just in case someone wanted to have a look at what I use and the general setup and configuration for my software and hardware.


I live about 10 km north of Oslo. The location have a nice (radio) view over large parts of Oslo and the surrounding areas, which is ideal for APRS infrastructure. I think we have the highest number of APRS users in this part of Norway, so a working infrastructure is crucial. We also have a fair bit of SAR usage on APRS, so my setup is tailored for both normal APRS and high-rate beacons from lots of trackers.

The TinyTrak4 used to be my “go to” TNC for this use. It’s stable, quick and easy to configure, but unfortunately it lacks some of the more advanced features. After tinkering with the software TNC “Direwolf” for a while, I thought it was time to give it a go under live conditions. As a fill-in digipeater with some extra features, it’s quite straight forward to set up. It currently runs on a Raspberry Pi 3 with a “no name” C-Media USB soundcard and a crude PTT circuit, which is then connected to my trusty old Yaesu FT-7800 (discriminator output). The software TNC also sends data over a TCP KISS-port to APRX (LA1HSA-1), which then i-gates traffic (bidirectional for objects, messages and selectable TCPIP only stations).

The digipeater (LA1HSA-2) will respond to the following unused paths:

  • WIDE1-1
  • TEMP
  • SAR3-3 to SAR1-1
  • LA1HSA-2 (a digi should always respond to its MYCALL!)

Callsign substitution is of course activated, so everything should be traceable.

The antenna is Diamond X-510N on top of a 10m high mast, fed with Ecoflex 10 (changing to Ecoflex 15 when I have time). This antenna provides a high gain and is suitable for my QTH. The TX power is about 10 Watts.

Here’s a little map showing stations heard directly during some months. Note that this only shows stations transmitting full paths, like WIDE1-1 or WIDE2-2. assumes that a path of WIDE2-1 has been digipeated, but not inserted its callsign. There’s also quite vast areas that never sees a person sending a beacon, so the main roads are probably the only places you’ll see someone sending their position.

APRS coverage for LA1HSA

APRS coverage for LA1HSA

This picture is a superimposed stack of pictures from I’ve since improved the reception a fair bit with the use of Direwolf.

Since I run this on a Raspberry Pi 3 and have “loads” of CPU power available, I’m thinking of expanding it a bit further. I have an idea for our SAR usage which involves cross-band digipeating to free up time slots for more trackers in the field. With 40-50 trackers deployed, there will be issues getting all packets when they transmit on the same frequency and perhaps have to be digipeated at the same time. The solution might be a digipeater that receives on one (or perhaps two) 2m-frequencies and digipeats them on 70cm or maybe even 6m. On the other end, I could have an i-gate that receives on the digipeater’s frequency. To make sure the digipeater can keep up, I might use 9600 baud or 2400 baud (Direwolf allows me to do all this). A simple cross-band digipeater could possibly consist of a Raspberry Pi Zero and two soundcards connected to two commercial high quality radios. This is on the to-do list and should be in a test phase during this summer.

Here’s a picture showing the APRS radio, the old repurposed project box that contains the

Yaesu FT-7800, Kenwood TW-4100E and Raspberry Pi 3

Yaesu FT-7800, Kenwood TW-4100E and Raspberry Pi 3

Pi (the box was originally an old stereo amplifier I worked on when I was 12 years or so). It also shows the radio that takes care of my Winlink gateway (70cm 1200 baud packet, LA1HSA-10).

I think I have to revisit this topic a bit later, I have more things to polish and try out before anything is definite. It’s working great though, and the best part is that it’s very easy to reconfigure anything on the go wherever I am in the world (if needed). A mobile phone with SSH is all I need 😉


APRS in my car – TM-D710 or FTM-350

Wow, it’s been a long time since I posted anything here – so sorry for that! I’ve been too busy to think about my hobbies, unfortunately. To sum it up in two words: Work + XYL.

feel that I have to make a little rant about todays APRS-capable transceivers, namely the Kenwood TM-D710 and the Yaesu FTM-350. I just traded in an Icom ID-E880 DSTAR-radio for the FTM-350 (don’t get me started on the ID-E880..). I was hoping that the FTM-350 would be way more user friendly for car use as it has an awesome display and well laid-out user interface. Indeed, in some places the FTM-350 shines like no other radio I’ve used. The display can be customized with colors, text size and other parameters to look at. The buttons and ease of access to common functions is as expected from a Yaesu radio. A bonus is that the display light can be set to match my instrument lights (BMW orange-ish). I also like the fact that you can chose to connect the microphone to either the base or the remote panel – neat! The remote panel also contain two small speakers, but they’re too weak to be of any use in a car. I recommend connecting an external speaker anyway, so I won’t make an issue out of it.

The FTM-350 is marketed as an APRS-capable radio, which it is, but when you start looking at the flaws or

Yaesu FTM-350

Yaesu FTM-350 in car

misunderstood implementation from Yaesu, I think you should think at least twice before you select this one instead of the (older) TM-D710. I might be a semi-advanced user of APRS, so my view on this might be a bit biased compared to people who just want to use a “tracker”. Please see my pros/cons list further down, it’s a lot easier to explain what I mean in a table instead of a huge wall of text.

The TM-D710 has been around some years now and it certainly is a good and


Kenwood TM-D710

capable radio with lots of features. Sadly, it lacks user-friendliness when driving a car. I don’t encourage people to make changes on the radio while driving, but sometimes you just have to change to a different memory channel or take a look at where you’re transmitting. Yep, the display on the TM-D710 could use some tweaking. One major gripe is that the alpha-tag of the memory slot is so small, while the frequency is in huge letters. Why couldn’t it be switched over? You might not agree, but I think some customization would be a good idea so it suits the user. More details in the table further down..


Good Nuissance Minor flaw Major flaw
FTM-350 TM-D710
Many selectable colors Can only select from two eye-straining colors
Can be set to single mode (hide APRS-part) Will always show A and B-side
Very good TX audio Good TX audio, although not as clean as FTM-350
No fan noise Noisy fan, although not Icom-style, but still loud
Integrated GPS (option FGPS1) Have to use external GPS – more clutter
Received beacons only show up ONCE until you delete the station list All received beacons can show up as you want them
Transmitted beacons does not show digipeat-path if heard Transmitted beacons can show all heard digipeaters and their path
NO digipeater functionality! (Severe flaw) Has all functionality to be a proper digipeater
No access to internal TNC so it can be used for packet or external APRS control (although it can send data out to serial) Full access to internal TNC so it can be used for APRS or KISS
Menu-driven squelch adjustment (no pot) Dual physical squelch control
Nice readout of alpha-tags and/or frequency Alpha-tags are very small while frequency is shown as huge numbers
Receiver seems poorer, it can’t decode packets as good as the TM-D710 Receiver can decode packets with lower S/N-ratio then the FTM-350, but nowhere near as good as a TinyTrak4/Yaesu FT-7800 combo
Transmitted beacons seems to hit fewer digipeaters than the Kenwood at the same power level Transmitted beacons is successfully decoded more often than the Yaesu
Wide receiver that also supports AM air-band and broadcast + FM wide broadcast (even has line in) Supports FM a fair bit up in frequency, but no FM or AM broadcast
Microphone can be attached to radio or remote panel Microphone has to be attached to the radio (base) and in 99% of all cases extended to be useful in a car
Speakers built into the front panel (although they are small for car use) Have to use external speaker as the speaker in the radio most often will be tucked away to reduce fan noise
Display can use different colors for different information, customizable Display can only show alternative color for emergency beacon and messages
No profile memory Has profile memories, very smart when you want to use different setups according to the situation

As you see, there’s quite a few differences between the two radios, and I haven’t mentioned them all just yet. Why can’t at least one manufacturer make THE radio for once? Both the Yaesu and Kenwood have their pluses and minuses, but there’s no hands down “best radio” as far as I see it. On top of all this, you have different standards when it comes to digital voice, but the most evolved “standard” is the DSTAR system. I’m currently not too fond of DSTAR, ’nuff said (keyword: Icom).


Wishlist for a mobile dream-rig:

  • Large customizable display (size like the FTM-350)
  • Color LCD or even OLED? You could get rid of the distracting backlight if you used OLED, but it would probably suffer in very bright (sun) light. Not a big problem here in Norway as 75% of all my driving happens when it’s pitch black outside.
  • Discrete TNC that can be used however you want when connected to external devices
  • Built-in digipeater with features like the ArgentData OT3m (options connected to the radio base)
  • Full-blown APRS like the TM-D710
  • Multi-band: 2m, 70cm and hopefully 4m
  • All mode! When was the last mobile 2m all-mode rig produced? Disregard the HF-capable rigs.
  • DSTAR (even though I don’t like it, it would be nice to have it in the same box as APRS)
  • Choose where I connect my microphone (like Yeasu)
  • Capacitive touch-screen if the user interface at least have physical buttons for common “operate-when-not-looking”-functions (VFO, volume, squelch, beacon on/off).
  • Integrated GPS (with external antenna if needed)

I guess I could go on forever, but I might just post a follow-up later..