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 preparation for deploying more systems in Iceland this summer – I updated our spare Piksi Multis and did a garden test. It performed very well!
I set them up to fix at 10Hz but report every 5 readings – so its closer to our slow system in Iceland. The fix hopped around within about 1.5cm – which is good for my garden as the sky box is not that wide.
Today we set up two dGPS units to measure the speed of some of Fjallsjökull glacier. We chose an area of ice which is clearly moving forward towards the lake.
Here is the dGPS system setup on Fjallsjokull, with Jane Hart and Frey
The photo above shows a “quadpod” supporting the GPS units – which are an adaptation of those made by Matthew Roberts of the Icelandic met-office. The idea is to be strong enough to cope with winter and cast few shadows (which cause ice to grow). The system is currently measuring its position every 3hrs to an accuracy of about 2cm – using signals from the base station to help it.
the dGPS base station installed on a moraine close to the Fjallsjokull glacier. We used speaker stands burried in rocks to support the GPS antenna (top) and hold its 2.4GHz radio antenna (white stick). Shortly after this photo I accidentally kicked sand into the laptop keyboard – so it was not so easy to use after that!
View of Fjallsjokull with our deployement being almost in the middle of this photo.
Here you can see the new shape of the 2013 base station – without wind generator (extra solar panels instead), new panel Wifi antenna on the top, new camera just below that and Topcon dGPS on the very top now. The structure has been reinforced with recovered parts from the damaged and decommissioned GPS pyramid.