Author Archives: Kirk Martinez

Sensor Network working well today!

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This sensor node links our radio network up into the peat study area

This sensor node links our radio network up into the peat study area

In order to cover the study area over the ridge – we placed this sensor node in a strategic place so it passes traffic across. By this time the packets have come 3km up to the mountain then 1km across to this node – then another 600m down to the peat area.

All this with 868MHz radios running IPv6 (6LowPAN) and CoAP to gather the data!

Arthur-router2

Arthur – our superb intern team member this summer has worked very hard to get the CoAP layer working for the system and has now seen it in action on the mountain.

Testing CoAP for node communication protocol

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In 2014 we implemented an HTTP/web interface to the sensor nodes to test how much easier they would be to manage. This was successful but the large number of packets exchanged made it slow (not surprising).

In 2015 we are testing CoAP instead – as it is essentially a compressed binary form of HTTP – and only uses UDP packets – so there are far fewer radio exchanges. Initial tests in the lab with our CC1120 868MHz driver show it is very efficient – and we are now porting large parts of our code to use it. We will still be using Protocol Buffers – as they are also small binary compressed objects for data – so we should have the best of both worlds!

Connecting from desktop to IoT sensor node!

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ping-a-node-from-soton

What this shows is a “ping” from a computer in Southampton going all the way to Glen feshie (last part via satellite link), through our “border router”, across to a node via the low power radio. It took around a second for the reply to get back to Southampton. (The IPv6 addresses have been blurred to prevent attacks).

For techies: the interval is set to 10s to prevent overloading the low power network and the packet size is set to 25 so it is small (6LowPAN prefers small packets)

relay node

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Phil and Graeme building a relay node on the ridge

Phil and Graeme building a relay node on the ridge

There are key “hops” in the network which require a node to route traffic. These “relay nodes” are key to the links and have a tripod to raise their antenna slightly – which is a higher performance antenna too. Before leaving for the winter we pegged it to the ground to test its strength.

border router now installed

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The system relies on a directional radio link down from the mountain to a sensor node attached to a small Linux-based computer. This is a picture of the setup in a shed in th Estate buildings. We are using an Atom-based mini-ITX computer which routes data from the low power 6LowPAN network to the Internet via the Estate’s satellite link.

ND6_0869 (Medium)

 

This Yagi antenna provides the directional link over 3km to the mountains

This Yagi antenna provides the directional link over 3km to the mountains

Laser scanning

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ND6_1351 (Small)

Thanks to the estate’s buggy we could take all the laser scanner gear up the track to the site easily.

ND6_1352 (Small)

Once the targets are set up the scanner captures a 3D map of the study area – in this case some stone banked lobes

Testing the radio links in the Cairngorms

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the antennas were tested in glen feshie - between th eestate buildings and the ridge 3.8km away and performed as well as we expected with the TI CC1120 transceivers. We now have a way to link the mountain's sensors to the web!

The antennas were tested in Glen Feshie – between thevestate buildings and the ridge 3.8km away and performed as well as we expected with the TI CC1120 transceivers. We now have a way to link the mountain’s sensors to the web!

this shows the distance covered by our first radio "hop" up to the mountains

This shows the distance covered by our first radio “hop” up to the mountains