7. Now, slowly adjust the trimmer in the probe body until you
achieve the best square wave shape that you can. By this we
mean nice square corners and minimum over and under shoot
near the edges. A small amount of over shoot is preferable to
an adjustment with “curved” square wave corners: this would
mean that the scope will attenuate high frequency signal
components whereas a small amount of overshoot will mean
that the scope will tend to slightly amplify high frequency
signal components.
A typical trace, after compensation will look like this.
Some deviation from this is normal due to variations in probe
performance. It is possible that on lower cost, lower
bandwidth probes that you may see a larger amount of
overshoot near the edges. This overshoot may be very
narrow and seem to come and go…this is normal. Better
quality scope probes have better transient response and so
have smaller overshoot.
Elan Digital Systems Ltd.
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USBscope50 USER’S GUIDE Iss8
