We have been doing more tests on the Swarm pico-sat coms with a view to using their system in Iceland.
This graph shows the temperature measurements during 6 days – showing the solar panel charging. On average the modem used 52mA but the battery was providing more like 120mA due to the LEDs and feather board.
Swarm have a system of tiny satellites (11x11x2.8cm) for low data rate communications anywhere on earth. This enables lower cost data access to very remote places.
In my first test I received my message on their Dashboard within a minute (I was not timing!)
A maximum of 192 bytes can be sent on one message – which is OK for batches of sensor readings. Their cloud (“Hive”) has a RESTful API to gather the data easily. We look forward to building an environmental sensor network test with the help of the Swarm team!
In our mountainsensing project we showed that fully standard communications could cover large areas. For that project we had to add an 868MHz transceiver to our designs. This year we are doing a lot of development with the Atmel SAMR30 based system-on-chip as it includes a sub-GHz radio and has good support in the RIOT-OS. One important thing to test was the typical range to make sure it was similar to our roughly 1km with the previous CC1120. Here is a photo of a quick test in the New Forest which achieved 1km with this set of antennas:
The Fjalls tracker has restarted – perhaps uprighted itself – and data is now coming in daily again. The gap in the data shows that it coul not create accurate readings then – which could also be due to a problem with its base station..
the distance moved by one of the Breiðamerkurjökull nodes shows us the glacier has started moving again – at a rate comparable to the previous autumn. Its also great that this prototype node has sent data so continuously – right through the winter!