Tutor and students at the ERA base location viewing the video feed and communicating via VoIP with the field geologist. Howick, Friday 07 August 2009
The curse of ERA – bringing sunny weather to field trips – strikes again! Despite packing gaiters, gortex, and waterproof sample bags to protect our kit, it was the sunshine rather than the rain that was the challenging weather for the Durham area field trips.
Jokes aside, we’ve had great weather, mainly sunny with the occasional light smattering of rain. This is actually a significant factor for us when we’re working in the field. The radio signal isn’t affected by rain to any great degree, we’re fairly confident that students will dive for cover before the radio signal deteriorates too far in rainy conditions, but we have to watch out for sun and rain when it comes to using the equipment in the field.
We’re aiming to use off-the-shelf, consumer equipment as much as possible so as to come up with a solution that could be taken up by the greatest number of other educational institutions. There is heavily ruggedised military-specification equipment for most of what we’re doing but the cost and weight factors puts this out of our league and probably would make the ERA system much less likely to be adopted by a broad community of users. Continue reading →
Chris on Whitby foreshore testing voice and video, with field antennae in the background
Today we went to Whitby to explore the field localities on the beach there, and also to see how far we could connect using just a single node.
In the morning we set up the base station in the car at the top of the cliffs, with a single Nanostation 2 access point, and Chris and Trevor headed off down onto the shore to explore the site. Quite a walk across the rocks and onto some interesting geology below the tide line, and with a turning tide Mark was posted not only to watch their progress but also keep an eye on the North Sea!
We made a really solid connection with two Nanostations connecting to each other and streaming voice and video smoothly between the two Asus Eee PC laptops that were connected by wire to these access points. A good few hundred metres distance covered, data to be analysed. Testing had to be cut short though as the incoming tide threatened to cut off the shore team and so it was off for the fabled fish and chips of the town for lunch.
The afternoon saw us back in the same location, but exploring how far we could push a signal from just a single Nanostation access point to a laptop on the beach over a couple of hundred metres. We ran iperf ans iwscan tests to check bandwidth and jitter rates and then tried setting up video calls. Suprisingly good connectivity was made, despite the distance. Clearly though we’re pushing the edge of what the kit can do and we found that by locking the video back to 2.048Mb/s from 3.096Mb/s give the audio a greater slice of the bandwidth and really improves its quality. Good quality audio really feels the key to giving the sense of an assured, seamless connection. We had a couple of crashes with the Ekiga video software at the edge of its range but generally this seems to be working really well on the Asus 901 PCs. We’re using walkie talkies as a backup channel as we know we’re pushing the equipment to its limit and will lose signal sometime; with line of sight we’re assured we can chat to each other, which is more than we can assume with mobile phones here!
We gathered the GPS readings from all the locations and we’ll put up the details shortly.
Today’s visit brought us to the dramatic coastal features of Scremerston, just south of Berwick-upon-Tweed. This is a tough location for Assisted Requirements students as the high, steep cliff face can be quite challenging to negotiate for anyone. The closest practical access is down a gravelled lane (which could be driven up at a push), stopping before the gate to a muddy field full of cows. From there, the beach site (which should be visited on a falling tide) is accessed down a grassy cliff face 300m or so from the gate. From the beach access, the geological study site is quite stretched out along the sea front, with features jutting out from the cliff base into the sea.
Screenshot of Nanostation 2 bandwidth testing at Old Wolverton, displayed on Asus Eee PC running Ubuntu
Today we carried out our second set of field tests. This time using our new Ubiquity Nanostation2 wifi routers. In the morning Chris, Mark and John started with a radio site survey, then did a single wifi link of about 460 meters, and had a quick check of the video streaming software (mjpgstreamer) in one direction and a two-way voip call.