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NORM/VERT trigger source on 2440 family


Jeff Woolsey
 

I can't figure out how to do this:  Display two independent signals
close in frequency, but with both triggered and stable.

(w2aew video #19 shows how ...) On many analog scopes, such as my 2235,
in dual-trace ALT mode, a switch selects CH1, VERT, or CH2 for A (&B)
INT triggering.  In CH1, CH1 is stable and CH2 is free-running.  In CH2,
CH1 is free-running and CH2 is stable.  In VERT, the CH1 sweep is
triggered by CH1, and the CH2 sweep is triggered by CH2.  Both traces
are stable.  This doesn't work in CHOP mode.

On the 2440, one can also trigger a dual trace display by one channel or
the other, with one stable and the other free-running.  There is a VERT
A-trigger source that displays CH2 only if CH2 is displayed and CH1 is
not, or CH2 and MULT only. The closest I can come to what I want is
SINGLE SEQ or SAVE, which gives me a stable snapshot of both traces, but
it's not realtime.  I fear that the capability I want is designed out of
the scope since both channels are always acquired simultaneously, it
always wants to display an accurate time relationship between events in
either trace.  An analog scope can only display one signal at any given
instant, playing games with ALT or CHOP to give the illusion of
simultaneous display of events, which can be satisfactory for recurrrent
events, but in reality for any given event, what the other trace did at
that instant is at least a sweep away, if it recurs at all.

So, am I right in thinking that this is a sacrifice we made for the
impossible-on-analog-scope things we like so much?

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire


Szabolcs Szigeti
 

Hi,

I don't think this is possible on the 2440. This scope closely mimics the
controls of the analog scopes, but inside it works differently. Both
channels are acquired simultaneously and constantly at the same time into
the CCD chain and they are transferred to the display when the trigger
event happens. So there is no separate "sweep" and triggering for ch1 and
ch2. And obviously there are no chop and alt modes.

Szabolcs


Jeff Woolsey <jlw@...> ezt írta (időpont: 2020. aug. 17., H, 8:08):


I can't figure out how to do this: Display two independent signals
close in frequency, but with both triggered and stable.

(w2aew video #19 shows how ...) On many analog scopes, such as my 2235,
in dual-trace ALT mode, a switch selects CH1, VERT, or CH2 for A (&B)
INT triggering. In CH1, CH1 is stable and CH2 is free-running. In CH2,
CH1 is free-running and CH2 is stable. In VERT, the CH1 sweep is
triggered by CH1, and the CH2 sweep is triggered by CH2. Both traces
are stable. This doesn't work in CHOP mode.

On the 2440, one can also trigger a dual trace display by one channel or
the other, with one stable and the other free-running. There is a VERT
A-trigger source that displays CH2 only if CH2 is displayed and CH1 is
not, or CH2 and MULT only. The closest I can come to what I want is
SINGLE SEQ or SAVE, which gives me a stable snapshot of both traces, but
it's not realtime. I fear that the capability I want is designed out of
the scope since both channels are always acquired simultaneously, it
always wants to display an accurate time relationship between events in
either trace. An analog scope can only display one signal at any given
instant, playing games with ALT or CHOP to give the illusion of
simultaneous display of events, which can be satisfactory for recurrrent
events, but in reality for any given event, what the other trace did at
that instant is at least a sweep away, if it recurs at all.

So, am I right in thinking that this is a sacrifice we made for the
impossible-on-analog-scope things we like so much?

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire





Roger Evans
 

The 2440 does sample both channels simultaneously every 3.3nsec so if you set the timebase to the fastest real time rate and single sequence you will get what you want but maybe not with adequate time resolution.

Regards,

Roger