Last year there was no one particular HAB project that really stood out as pushing the bounds of HAB flight. There were, though, may incremental steps taken in the improvement of the LoRa system of radio broadcast for trackers. So what is LoRa anyway and what makes it special?
LoRa is a radio broadcast system that offers higher bandwidth than is generally achieved by HAB flights that use RTTY. LoRa also allows for an uplink to a radio tracker since the modules used in the radios are transceivers. This means they receive signals as well as transmitting them.
A LoRa gateway is a LoRa transceiver connected to a computer and controlled by software that reads incoming packets and uploads them to habitat, in the same way that dl-fldigi does. The computing requirement is minimal, and anything that has an SPI interface and internet connectivity can do it. Freed of a PC, gateways can be made small and waterproof and put up near the aerial. Tom (SP9UOB) has done just that – see http://sp9uob.verox.pl/LoRa/lora-gateway-inside.jpg. Very neat. Something like that can be left on all the time, and remotely administered, at much lower power consumption than a PC. Most people use Raspberry Pi for this as it’s cheap and convenient. The combination is a lot cheaper than a laptop and radio or SDR.
LoRa systems can be found for existing trackers that use the most common protocol: RTTY. Pi in the Sky, for example, has an optional LoRa board that stacks over the RTTY transmitter board. The PITS software supports LoRa (and APRS for that matter) and can transmit any combination of LoRa, APRS and RTTY at the same time.
HAB enthusiasts are currently developing software to run both RTTY, APRS, and LoRa at the same time. An example of this is Flextrack AVR tracker software developed by Dave Akerman .
One of the nice things about LoRa is that you don’t need a PC – as I said anything with SPI and an internet connection will do fine. A Pi is cheap and convenient, or a cheap Arduino with an ESP8266 wifi module could do it, albeit with a bit more effort.
This article was put together with a lot of very useful information from Dave Akerman.