Sunday, 9 November 2008

Ana...nother thing or two about the SD1

Earlier in the year I described my impressions and opinions about the Anabat SD1, describing it as "God's own bat detector" (August 2008). Since then I have had many more opportunities to use the machines in a wide variety of situations and discussed them with a number of people, including those who were kind enough to reply to my post with advice and information (thanks!).

One thing I commented on then was the option to pay nearly £450 extra for a PDA (hand-held computer) mounted on a bracket on the front of an Anabat. This delivers the opportunity to view live sonograms as bats fly past. Although a great teaching tool and potentially quite useful in the field I had strong doubts about whether this was a realistic option as it is a lot of cash to lay out on something which would be vulnerable to damage in the field, unlike the Anabat on it's own, which is quite robust.

After receiving some intriguing emails I decided to look for an alternative way of achieving the same end. I spend quite a bit of time training bat-workers and a way of displaying live sonograms without touting a lap-top around could be very handy.
The finished SD1 + PDA + GPS in use

Chris Corben, who designed the Anabat, has an excellent website, full of practical suggestions, based on his own experience of using Anabats (see below). This includes a step-by-step idiot's guide to setting up a PDA to work with an Anabat and even some advice on PDA models known to work. A look on eBay revealed that some of these are out-dated for more advance puposes and are therefore available cheaply second-hand. A few days later I had an HP Ipaq HX2190 in my hands for the princely sum of £38.25. It came with the cables and cradle to charge it and link it my home PC. Following Chris's notes it was remarkably easy to install Anapocket (the PDA version of the Anabat software - it comes free with the Anabat) onto the PDA and I was quickly able to view sonograms I had recorded previously.

Next I needed to connect the PDA to one of my Anabats. The cable used for this is the same as those used for synchronising a PDA with a PC - I just needed to find one with a serial plug rather than the more usual (nowadays) USB plug. Once again eBay came up trumps (£3.85). Hey presto! Live sonograms - it really was that easy.
The next thing I needed was a bracket to attach the PDA to the Anabat, so I could walk around with it. There are three threaded holes on the SD1 case, designed to take bolts on the standard bracket. These are simply M3 machine screw holes (the bolts are readily available from DIY shops). I considered making a bracket out of some aluminium or brass sheet, with two folds to make the required U shape. I remain concerned about the vulnerability of the whole set-up and decided instead to make a bracket out of 7 mm foam board - a lightweight yet strong material used in building exhibition displays etc and available from large stationers.

A little experimentation showed the best size and shape for three pieces to create the bracket (email me if you'd like a copy of this). A little Araldite and spray paint (the latter more cosmetic than anything else) and I had a strong, yet light bracket. I attached the PDA to the bracket using stick-on velcro strips. In the event of the unit being dropped or bashed against something the foam board is likely to break before the PDA, so my small investment will be safe. More importantly, so will any survey data on the PDA.

To make the most of this new set-up in the field I needed two more things: a spare battery for the PDA and a CF GPS unit to plug into the top of it. It is possible to use a Bluetooth GPS with the PDA (if, like my one it is Bluetooth enabled, though I think most are), but Chris mentions experiencing problems with the GPS and PDA losing contact from time to time. I also think that, when using an automated GPS in the field, there is a danger of the GPS losing the satellites and the user being unaware of it. Having the GPS plugged into the top of the PDA means it will always be held upwards, unshielded and in the best possible position to retain a view of the GPS satellites.

In my earlier piece about Anabats I bemoaned the fact that, when using an Anabat with a GPS, it was necessary to manually cross-reference bat passes against a GPS file to get a grid reference for each bat. Using a PDA with GPS resolves this problem and now all my bat passes are automatically grid referenced by the PDA. I also questionedthe problem of losing night vision by looking at a PDA screen in the dark. Even turning down the PDA brightness to minimum may leave it too bright. I had heard a Titley employee describing keeping the PDA facing away when not looking at it, which seemed rather self-defeating. I have resolved this by changing the colours on the screen, so that the background is black and the sonogram traces and Anapocket menus are the only things in a bright colour.

The PDA screen, with the Anapocket background set to black, to reduce glare.

So now I have a great teaching tool, a really good toy and a solution to the problem of GPS-referencing bat passes. Compared to the £450 it could have cost I actually paid a total of £61.63 (plus a bit for postage and packaging). I still think it's a Heath Robinson approach and vulnerable to damage, but I don't mind that so much when I've saved £387. After several decades of living in Scotland, something seems to have rubbed off....

Chris Corben's Anabat website:

Anabats in the UK are sold by Alana Ecology, who are usually knowledgeable and helpful:

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