Date: Wed Oct 29 13:46:40 2008

Author: Bernard Cleyet

Subject: Re: oscilloscope renewal

Post:

A discriminator is easily constructed, especially for multi
microsecond pulse widths -- look in Elmore and Sands.

bc vacuum tube man.


On 2008, Oct 29, , at 08:45, J. Terrence Klopcic wrote:

> On the subject of oscilloscopes.
>
> We have made a disappointing discovery in connection with our new
> Tektronix digital oscilloscopes.
>
> One of the handy uses of a scope is to find random signals in a
> noisy background. The way one can do this is to set the trigger to
> the "Normal" mode. (In this mode, the scope does not sweep until a
> pulse exceeds the trigger level.) One then starts with a low
> trigger level - which displays the noise - and slowly increases the
> trigger level until the noise disappears. At that point, the
> sweeps are all initiated by pulses that exceed the noise level -
> and one can judge the frequency of such pulses by the persistence
> of the traces which overlap at the beginning of the trace.
>
> Not so with the Tektronix TDS 2022. That scope has a Persistence
> Setting (0, 1, 2, 5, or infinite seconds) for individual traces - a
> very handy thing if one wants to study individual traces. However,
> in the Normal mode, the only choice is infinite! Yep - no matter
> what, the scope displays the previous pulse until superseded. When
> contacted, Tektronix replied that such behavior is "Industry
> standard". Yuk! Why offer a Persistence setting and then
> automatically over-ride it? It is a disappointment.
>
> Anyone else bothered by this behavior and found a work-around?
>
> Terry
>
> J. Terrence Klopcic, PhD
> Director of Laboratories
> Departments of Physics and Mathematics
> Kenyon College

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