Bats! Status

 

Status of the Bat Project:

The Bat Project has now been running in anger for over two years. I sometimes wonder what it was like to have free time - this project has grown and grown, and has proved to be rather more complex than I first imagined. No real problems there, rather my perspective of the project has moved from a purely academic exercise towards a rather more pragmatic business view... Bear in mind, I do have a full-time day job (and a family!). To do this I've been getting up at 4 or 5am, working until 6:30, getting the kids ready for school, waking my wife at 7, getting the train at 7:20, working for an hour on the train, working on it for an hour at lunch and again on the train home, and if I can, doing a couple of hours late in the night after everyone else is in bed. Luckily, I only need about 6 hours or less sleep a night... Least that sounds a bit over the top, I did have 20 days off for sailing this year, plus we spent some time skiing in Åre (pronounced "Oar-er") in Northern Sweden, so its not all work...

The initial idea was to produce a hand-held unit that allows a field worker to fully analyse a bat's calls and hopefully to use AI techniques to suggest what type of bat it might be. Many PhD students have tried and failed to make this approach work, but it takes more than a few failed theses to daunt me (stupidly).

Originally, I approached my alma mater, Southampton University, for advice. Due to the necessity of making money from anything (even probably making the tea) (cynic), they were not very helpful, however they did point me in the general direction of other academic researchers who have been extremely helpful. One, it turns out, lives adjacent to my in-laws' farm in East Sussex, and these kindly folk have aided me greatly, mostly in the area of functional requirements. Others have helped me by allowing me to bounce technical ideas off them, and have provided much welcome constructive criticism.

The unit is now rather awesome. It contains the very latest low power digital signal processor, running at over 150MHz, highly accurate digitising circuitry, a beautiful high-resolution graphics display, loads of memory, an expandable file system, a USB interface and much, much more... Oh, and it's only slightly larger than current top-end detectors... actually, its smaller than many, and anyway, if offers facilities that are so far beyond anything on the market, or even proposed, its all bit bit shocking...

Much of the work is still under wraps. I have had some ideas that are unique in this field, and which have never been considered practical before. As my device is very much state-of-the-art, many of the components are newly in production or only available as samples at present. PCB design is critical at these sorts of frequencies, and the software and hardware development environments are very very expensive - the ICE alone is USD 2,000, and the whole environment easily exceeds USD 25,000 (compilers, debuggers, ICE, JTAG programmers, arbitary function generators, digital storage 'scopes, ultra-high speed logic analyser, etc.). All the technology is low or micro-power surface mount, so I have had to invest in very good SMT reflow equipment (another USD 5,000) - you can't use soldering irons for this stuff, many of the devices have pins that are small fractions of a millimetre apart. The PCB is a 4-layer 8thou design with a significant number of VSLI devices, including the DSP, RAM, FLASH, CPLD etc, apart from the ADC/DACs and analogue circuitry. Did I mention that we've also converted some outbuildings into a lab with a clean supply?

The mathematics involved in the DSP, and the development of real-time filtering and analysis software that can capture, process, analyse and display up to 500,000 samples a second, is a challenge. The filtering allows a number of extremely clever tricks, such as compensating for transducer non-linearity, time-expansion, frequency division and heterodyning. Not only that, but it allows you to take a previously recorded signal and analyse it as if it was a live bat, even if that signal has been frequency shifted, expanded or divided and converted by another unit.

The graphics display provides the user interface as well as displaying analysis results. Its high-resolution and efficiently backlit. Real-time spectral analysis and sonograms can be displayed, allowing zooming, panning, analysis and correction for a number of influences. You can select sections of calls, process them, store and recall them, play them back as human audible signals or reconvert them back to ultrasound. Selected data can also be stored and recalled at will, or downloaded to another processor via a USB link - the device appears as a Windows disk to the PC.

Software updates are available over the USB cable from a PC, and can be downloaded from the web. This allows completely new functionality to be added to the device at any time. Factory diagnostic access is via on-board JTAG interfaces.

The above is a brief summary of what is going on - it does not mention many of the unique features of the device. Currently, I am designing the mark II PCBs - I can make 8thou double-sided boards myself, but I can't do 4-plane boards - internal power planes have to be done by a specialist board house, so I will have to wait for them until early January. Time permitting, the next version should be available in February 2002. I can't produce these devices for a few more months anyway, as some of the chosen logic will not be in full production until Q2, 2002.

If everything works out as expected, some mark II devices will be taken into the field in SE Asia in March/April 2002 which should be interesting! The devices will be taken into high-humidity jungle conditions for a month, and if they survive that, anything is possible. As I've tried to engineer everything to IP65/NEMA4 or better, I hope that there will be no problems. However, they could easily be eaten by a monitor lizard, or dropped from a great height...

So there you are. What started off as a simple idea one spring evening with the kids, has turned into a fairly major engineering exercise with as much, if not more, software and mathematical content as electronic engineering. A neat way to stretch my (highly limited) skills and (very tired) "intellect"...

If you have any questions about this project, drop me a line or use the guest book...

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