LoRa APRS

LoRa (Long Range) and APRS (Automatic Packet Reporting System) are two distinct technologies used in the field of amateur radio and wireless communication.

Derived from Chirp Spread Spectrum (CSS), LoRa is a wireless communication technology developed for low-power, long-range communication between devices.  It is often used in applications like the Internet of Things (IoT), where devices need to communicate over relatively long distances while consuming minimal power. Internationally LoRa operates in unlicensed radio spectrum (433 MHz, 868 MHz, 915 MHz for example), making it accessible for hobbyists and developers.  LoRa “encodes information on radio waves using chirp pulses – similar to the way dolphins and bats communicate! LoRa modulated transmission is robust against disturbances and can be received across great distances.”

APRS, on the other hand, is a system developed for real-time tactical digital communication between radio amateurs.  It allows for the exchange of position information, messages, weather data, and other relevant information over radio waves.  APRS is widely used in amateur radio for tracking and reporting the location of objects like vehicles, weather stations, and even individuals.

As previously mentioned, hobbyists and developers can work with LoRa using the unlicensed radio spectrum, but it ultimately depends on the specific frequency and the associated rules as issued by your region’s regulatory bodies such as the Federal Communications Commission (FCC) in the United States or the European Telecommunications Standards Institute (ETSI) in Europe.  In the Denver, Colorado area ARES R1D5 is leveraging our amateur radio licenses to experiment with LoRa in the 70 cm band, specifically 433.775 MHz.

Members of ARES R1D5 are using LoRa and APRS to primarily experiment with GPS tracking.  GPS tracking via LoRa is accomplished via two device configurations – the iGate and the tracker, which are different software configurations but can be the same LoRA PC board.  The iGate (Internet gateway) listens to the LoRa 433MHz frequency and connects to the Internet via Wi-Fi.  When the iGate receives an APRS position report from a LoRa tracker, the iGate sends an APRS position report to APRS-IS (www.aprs-is.net). The tracker device contains an onboard GPS receiver and uses a smart beaconing algorithm to transmit position reports.

Some ARES R1D5 members have a LoRA iGate setup at home. Some have a LoRA tracker in their vehicle.  Some take a tracker with them on walks and hikes.  Some do all the above and more.  LoRa trackers and iGates are becoming part of our best communications practices to effectively assist our served agencies at running events, bicycle events, and off-road motorcycle events.  Where no internet is available, the iGate can be programed to function as a decoder that passes position reports to a receiving station using PinPoint APRS software. PinPoint is a free to download APRS mapping application for Windows developed by ARES R1D5 member, Frank Watervoort, AB0WV.

Click here to see an aprs.fi “heat map” of LoRa position reporting activity for the current month.  In the future, ARES R1D5 has plans to expand our LoRa and APRS capability to include passing short messages over APRS or even to communicate via Winlink (www.winlink.org).

To get started with LoRa and APRS, you would need the following:

1. LoRa/APRS Hardware(There are more manufacturer options than shown below; however, at this time we recommend these specific devices based on our own experience and experimentation. The best prices tend to be on AliExpress, which is an online retail service based in China. If you are not comfortable with AliExpress, these devices can also be found on Amazon, eBay, and other websites. Regardless of where you shop and buy, BE SURE to select the 433 MHz version and not the 868, 915, or 923 MHz options.)
   • iGate: LILYGO® LoRa32 433 MHz version 1.6 through 2.1

• • Tracker: LILYGO® T-Beam Meshtastic 433 MHz soldered OLED version 1.0 through 2.1

1. • The cost of entry for experimenting with LoRA APRS is low with the above-mentioned iGate selling for around $20.00 each and the Tracker selling for around $35.00 each.
   • Both devices have a micro-USB interface for programming and power. Be aware that a micro-USB cable, power supply, and a protective case are not included.
   • These devices are one-to-many and many-to-one meaning there is no one 1:1 relationship between the iGate and the tracker. For example, you can start experimenting with just a tracker and take advantage of the existing distribution of iGates in the Denver.  Or if you have an unused UHF antenna on your tower and have been looking for something to do with it, you can attach an iGate and monitor the quantity and location of incoming LoRA APRS beacons.  Essentially you can get started with LoRa APRS one piece at a time.
2. Programming Software / LoRa APRS Firmware (Similar to the hardware, there are more available firmware options than are shown below. We recommend firmware being published by Chilean ham radio operator, Ricardo Guzman, CA2RXU).
   • Programming Software: Visual Studio Code. Free from Microsoft for private use.  Available for Windows x64, macOS, and Linux x64.
   • iGate Firmware: LoRa_APRS_iGate
   • Tracker Firmware: LoRa_APRS_Tracker
3. Programming Knowledge: At a minimum, you will need to edit a text file in Visual Studio Code to configure either the iGate or tracker devices. The LoRa software is public domain, and therefore free to use and change. This means the sky is the limit based on your level of interest and ability.
4. License: FCC issued Technician class or higher amateur radio license.

The LILYGO® LoRa devices do not include a case.  Protecting the circuit board and components with a case should be considered to ensure the proper functioning, reliability, and longevity of the electronics.

3D printing provides a great option for creating custom cases tailored to your specific project requirements and/or personal tastes. You can design and print cases that precisely fit your LoRa modules, antennas, and other components. There are case designs by others that can be downloaded and printed.  Thingiverse, a website dedicated to the sharing of user-created digital design files, is a great resource for ideas or just downloading existing designs to start printing.  PLA is a good 3D filament for controlled environments (i.e. your air-conditioned house), but it has a relatively low melting point compared to some other 3D printing materials and is not suitable for vehicles in the summer sun.  PETG, ABS, and ASA are a few alternative filament examples that are better to use for higher temperature (greater than 100F) applications.

Etsy is an online marketplace that allows independent sellers to showcase and sell their products.  Check out Etsy for 3D printed cases that you can buy.  If you find something you like but you really wish it was red and not blue, contact the seller to determine if they are able to create a custom solution for you.  Be sure to inquire about the 3D filament used if your application could be in an environment where the heat will reach or exceed 100F.

3D printing is not the only option.  There are plenty of off the shelf cases or project boxes that can be modified to house your LoRa devices and components.  You can go expensive with a Pelican case, or cheap with something you find at Walmart.  Home improvements stores have enclosures that can be retrofitted and supplies that can be used to fabricate a custom solution.  In general, consider checking online forums, websites, or communities where enthusiasts and developers share their experiences and projects.

The LILYGO® LoRa32 and T-Beam boards come with a very basic antenna and have a maximum transmission output of 100mW.  Maximizing performance involves two central aspects of the radio system, which are already familiar to most amateur radio operators: (1) antenna selection and placement, (2) transmission power. Replacing the antenna with a higher gain alternative and/or connecting to an outside the home or vehicle antenna will yield better transmission and reception results.

For the traditionalist, the default 100mW will be adequate for experimentation.  For higher performance an amplifier can be added to the system.  There are 5-Watt, 8-Watt, & 13-Watt inexpensive TX-only amplifier options that can be used for example in vehicle applications.  There are inexpensive 1-Watt bi-directional options that can future proof your system when future capabilities like 2-way messaging and Winlink are developed.  If you have a Mirage, RM Italy, or the similar UHF amplifier, chances are it too can be used to boost your effective radiated power.

For most applications, the small ceramic GPS antenna that comes with the T-beam tracker is more than adequate to lock on to the GPS signal; however, there are inexpensive (around $4.00 each) and more sensitive GPS antennas available that are compatible with the IPEX connector found on the tracker circuit board.  An example is this 33dB GPS antenna.  If you decide to upgrade the GPS antenna, be very, very careful when removing the factory antenna from the IPEX connector.  Take your time; slowly and gently pry the GPS antenna cable from the circuit board.  If you exert too much force you can break the IPEX connector off the circuit board, and it will be very challenging to solder it back on to the board.

***Hyperlinks above to amplifiers and GPS for sale on AliExpress are merely examples and not endorsements of the sellers.