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.
Local tests – mainly to debug the python code – of the ublox M8P have produced fast fixes today.
this is over about 30mins in my garden – using about 15 sats.
These new dGPS units seem to be accurate to around 2cm as shown in our test. This is for a close baseline (and at the moment doesn’t use GLONASS).
Testing the Piksi Multi from Swift Navigation. North/East relative position of rover – in a 96s test in an open space. The readings are quoted as accurate to 0.023m H 0.037m V.
carrying out a repeat Ground Penetrating Radar (GPR) survey of the glacier
For the last few years we have seen more and more of the lead for the 2008 wired probe be exposed due to surface melt. We were hoping that this year for the first time in Iceland we’d be able to recover it. When we arrived this year we found the lead going into a stream on the surface of the glacier, and with a bit of wiggling Graeme (shown below) was able to extract the probe.
Graeme with a wired probe from 2008 which has been recovered.
We’re looking forward to being able to open it up and see how well it has survived.