Posted 03 April 2007 - 08:48 AM
Looking at your data, it appears that your signal sits right at 0.0 volts, and then every once in a while you get a quick pulse. Initially the pulses are 2-3 volts, but then settle down to consistent ~0.5 volt pulses.
If you could get those pulses to go over 2.3 volts, then you can just connect the signal to a timer or counter input. As it is, though, you should use a comparator to condition your signal. Check out the MAX921CPA from maxim-ic.com. You can power this from VS on the UE9. That means that if IN+ is greater than IN-, you will get 5 volts out. If IN+ is less than IN-, you get 0 volts out.
The typical operating circuit on page 1 of the MAX921 datasheet seems to show the input signal put through a voltage divider. Your signal appears to be within the input range, though, so I think you can just connect it directly to IN+ without the divider.
In the typical operating circuit, they have REF=1.182 connected to IN-, so that is the threshold value. You want more like 0.3 volts, so pass REF through a voltage divider (try 100k/33k) before connecting to IN-.