Talking to a KISS TNC (ham radio, APRS)?

Good morning,

I have a project involving high altitude balloons. I'm aware there are a number of options but would like to confine this thread to the following parameters:

My balloon project will use a terminal node controller (TNC) to communicate through a radio in the way a modem used to communicate over the phone years ago. There are many resources for connecting a computer to the TNC using the KISS Protocol. But instead of a computer, I'd like to connect an Arduino.

I don't think this is all that hard, but with certain holes in my knowledge, clearly there is something I'm missing. Would anyone be inclined to share some code to do this that I can use as a reference?

Thanks,
-- Markus K1FIG

if you do a web search for arduino kiss there are plenty of links

Take a look at MicroModem, but there are lots of other telemetry options for high altitude balloons. You don’t need a license to use LoRa, and the range record is now over 800 km.

If you want to go the Amateur radio APRS route, then its likely an Amateur radio forum would be a better choice for information.

I dont recall and requests for information on APRS\modem stuff in here in the last few years, a lot of people have moved on to LoRa which readily allows for license free comms over hundreads of kilometers.

Using TTN (LoRaWAN) has recently become popular in Europe for HAB tracking although its not suited to sending commands to a balloon tracker due to fair useage restrictions which limit you to 8 messages a day. Sending commands to balloon trackers via point to point LoRa is easy and is used for downloading images from balloon cameras for instance.

There was a group in South Africa working on replacing the short distance modem\audio type comms used in the past with LoRa for a replacement and much longer distance 'APRS' system.

I did use TNC\Modems for sending messages back in the 1980s, but technology moves on ...............

ask here: QRZ mictocontroller forum

These are some great ideas! Let me respond:

  • I'm not looking to make the Arduino into a TNC. I'm looking to connect an Arduino to a TNC. (Currently looking at the TinyTrak4 from Bionics.

  • LoRa is not a realistic option. I believe that someone might have received a signal once from 800km away, but since LoRa's range is +/- 10km according to the wiki page (LoRa - Wikipedia). I need a range of 30km or more.

  • LoRa is a proprietary technology owned by the LoRa Alliance - members include IBM and others. I prefer APRS because it's open source.

  • I'm using an APRS strategy because I'm a licensed ham radio operator and those radios have the range. So I'm going to connect the radio to the TNC, then the TNC to the Arduino.

  • The QRZ suggestion is cool - thank you!

Thanks,
-- Markus K1FIG

MaineWebDad:

  • LoRa is not a realistic option. I believe that someone might have received a signal once from 800km away, but since LoRa's range is +/- 10km according to the wiki page (LoRa - Wikipedia). I need a range of 30km or more.

The Wiki page is huglely missleading, dont take what you read out of context, the 10km quote gives no indication of where the 10km range applies.

LoRa has been used for a while in the UK for high altitude balloon tracking, in part because we are not allowed to use Amateur devices airborne. Tracking ranges of 400km+ are the norm.

I myself once held the two way control record (for LoRa) at 242km back in 2015, the current distance record is now 832km using TTN and there have now common to achieve 700km+ for HAB flights.

If you only want a measly 30km, then 2.4Ghz LoRa will suit you fine, the current record for that is 89km, see here;

LoRa is a proprietary technology owned by the LoRa Alliance

LoRa is a proprietary technology owned by Semtech.

  • LoRa is not a realistic option.

What a strange thing to say, considering how popular it has become for balloon projects like yours!

LoRa is in fact the preferred option. You can even tap into existing LoRaWan networks to send your data.

I appreciate the perspective on LoRa. Here are some reasons I'm going with a 2m APRS solution instead:

  • 144 MHz (2m) has a greater range than 915 MHz, which is the LoRa frequency for North America.

  • I question if the reason LoRa is so popular with balloon projects is because folks don't want to take the time to get a ham radio license. If so, the popularity doesn't necessarily mean LoRa is a better solution.

  • In my rural location, we have tall mountains with APRS repeaters. While this doesn't matter when the balloon is in the air, it makes for better communication as the payload approaches the ground.

  • Websites like APRS.FI allow anyone (including students in the classroom anywhere in the world) to monitor a balloon flight or any other APRS beacon.

  • The 2m frequency works with existing radios and APRS gear that many ham radio operators use.

  • A 2m HT radio will broadcast at 5 watts max, as opposed to 1 watt (from what I've seen) for LoRa.

All that said, I think LoRo looks interesting and might be useful for other kinds of projects, such as a secondary tracker and perhaps having some payloads that interact with each other.

-- Markus K1FIG

MaineWebDad:
A 2m HT radio will broadcast at 5 watts max, as opposed to 1 watt (from what I've seen) for LoRa.

Do include the right context when reviewing power levels, LoRa has a range advantage over FSK type data transmissions of around 10 times, so to cover the same distance as a 5watt transmitter, a LoRa device would only need 50mW, thus much smaller and lighter transmitters and batteries.

Considering the current price of helium, its surely no surprise that HAB enthusiasts are looking for much lighter payloads.

In the UK most HAB flights are also tracked with FSK RTTY, which the LoRa device can produce. A low cost SDR is all you need for the receiver and the received signals are fed into the HABHUB online tracking system;

https://tracker.habhub.org/#!mt=roadmap&mz=2&qm=1_day&mc=42.95378,-88.33729&f=IT9ZOB&q=!RS_*;

Which has Worldwide coverage and accepts inputs from APRS, FSKRTTY (via FLDIGI), raw LoRa and TTN.

I dont know how heavy a APRS repeater would be, but a LoRa one would be circa 5g, and put airborne on a small cheap RC plane can allow you to search very large areas (for a landed balloons etc) in a matter of minutes, see here;

MaineWebDad:

  • I question if the reason LoRa is so popular with balloon projects is because folks don't want to take the time to get a ham radio license. If so, the popularity doesn't necessarily mean LoRa is a better solution.

On that point, getting a Amatuer radio licence is easy peasy these days, hardly an obstacle at all.

Most all the people I come across who use LoRa for balloon tracking are already radio Amateurs.