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Homebrewed LoRa APRS tracker

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 Gary
(@gary)
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Joined: 5 years ago
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I recently built a self-contained 1.5 Watt LoRa APRS tracker using a TTGO T-Beam board, AB-IOT-433 amplifier and an 18650 battery power bank. I managed to get it in a 5.1" x 3.1" x 2.8" enclosure. The tracker will easily run for 16 hours continuously on the two 18650 batteries in parallel.

If you aren't familiar with LoRa APRS, it is APRS using a chirp spread spectrum transmission method, which offers better coverage than the AFSK over FM transmission method used on "standard" 2 meter APRS. There are a number of folks using LoRa APRS here in the Denver area, mainly in Douglas County at the moment. The tracker board with GPS and LoRa chip are only about $40, or less, and it outputs 100 mW max. The results from just a 100 mW transmitter have been far better than what you would get with 100 mW using AFSK over FM. But, of course, adding a small amplifier to boost the signal to about 1.5 Watts helps the signal go even further. The tracker boards will usually come installed with Meshtastic, or other application, but you will replace those with APRS firmware.

There are also LoRa APRS iGate boards (TTGO LORA 32) available for about $16, which you can install at your QTH and send received LoRa APRS packets via the Internet to aprs-is, which then makes stations you receive visible on services such as aprs.fi. All of the iGates in our area are currently operating at ham's homes, many with compromised antennas due to HOA regulations. There are currently no iGates on mountaintops or tall towers, yet we have seen very good local coverage from our home iGates. 

So, the hardware to get started is quite inexpensive compared to buying off-the-shelf ham radios that have APRS built in. It will not take too much out of your ham budget to participate.

The tracker and iGate boards that we are using locally operate on 70 cm, so this is totally separate from 2 meter APRS. Note that the LoRa boards are available for both 70 CM and 33 cm bands, and there certainly is nothing to keep you from using 33 cm, but all local activity is currently on 70 cm, so be sure to order boards for 70 cm (433 MHz).

The ham community has written the firmware that you install on these boards, and new features are being added on a fairly regular basis. You do need to have some computer literacy in order to load the firmware onto the boards, but it is all part of the fun of learning how to get these homebrewed systems up and running.

There are 3D printer files available for printing your own cases for both the tracker and iGate boards. If you are into 3D printing, then there is more fun you can have with this project.

So, if you have an interest in APRS and want to try something new, then check out LoRa APRS as a homebrew project. Put up an iGate at your home and/or put a tracker in your vehicle, slap an external antenna on the trunk, and have some fun.



https://github.com/richonguzman


 


   
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