Saturday, August 30, 2008


The last few days have brought warm nights.
While sat in the garden sipping my amber nectar a bat flutters around my discone antenna. I have tried a few times to capture an image of this silent little creature. Is it really a bat I can see or is it a bird?
Well tonight I finally cracked it, here it is... a cute little bat!
Here it is close up...

Amazing to watch, flying at high speed twisting and turning but never bumping into anything.

So is it digital or analogue?

I works like radar a thing called 'echolocation'
Acoustic features of bat echolocation calls:
Frequency Modulation and Constant Frequency: Echolocation calls can be composed of two different types of frequency structures: frequency modulated (FM) sweeps, and constant frequency (CF) tones. A particular call can consist of one, the other, or both structures. An FM sweep is a broadband signal – that is, it contains a downward sweep through a range of frequencies. A CF tone is a narrowband signal: the sound stays constant at one frequency throughout its duration.

Definately sounds analogue to me!

A nice link for a more technical explanation:

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