Home Forums Meteors LCD Shutter Hi,

Bill Ward


Some objective perfomance,

First pic is the LCTec shutter running at 20Hz. The upper trace is the photodiode output. You can see how it is twice the frequency of the driving signal, lower trace.

The second picture is what I reckon is the best performance of the smaller, cheaper shutter. It only has the upper trace. Ignore the frequency on the image, the scope is picking up some of the much higher frequency noise. The drive signal was 6Hz giving 12 breaks/second.

You can see the photodiode output is much more rounded. This would translate into a “softer” edge to the segments of the meteor image. This might actually be ok for slow meteor measurements but probably just for purely aesthetic effect (and, rather usefully, differentiation between satellites and meteors!), we’ll see…

(The “delta T” is given as 85ms between the cursors. So working backwards gives a drive frequency of 5.9Hz so I don’t exactly have the cursors one pulse apart.)



Just noticed, 2011, I need to reset my clock!!!