Philips PM3350A - Zoom and Auto Zoom Functions.4

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4 APPLICATIONS
4.3.4 ZOOM AND AUTO ZOOM FUNCTIONS
The ZOOM and AUTO ZOOM functions are used to magnify a part of signal while
retaining full sample resolution over the selected part.
ZOOM
If part of the signal needs to be examined in more detail the ZOOM function can
be used. The main cursors can be set on the wanted trace and on the signal part
of interest, using the CURSOR SELECT menu and the CURSOR CONTROL menu.
Then by entering the ZOOM menu and activating the RESTART function, if within
the limits of time base and delay range, a new acquisition will be made in the
adapted time base setting and delay time. This means that the the selected part
is resampled using full memory and at a higher sample rate and so higher
resolution is used only on the part of interest.
The REVERSE function resamples at the previous settings (This function is only
active after use of the RESTART function).
The CENTER function sets the MAIN CURSORS horizontally to +2 DIV and -2
DIV from the screen centre. This helps to continuously zoom in on the signal part
of interest without having to return to the CURSOR CONTROL menu and then
back to the ZOOM menu.
After CENTERing the MAIN CURSORS, a new RESTART can be made.
The limitations for the ZOOM function are given as error messages on the
screen. The three possible error messages are:
NO RESTART, timebase limit reached
NO RESTART, trigger delay limit reached
NO RESTART, &t between cursors too big
The ZOOM mode is not active if the signal memory is locked. When locked, the
following error message is shown on the screen:
WARNING, oscilloscope Is in lock mode
4.3 MENUS AND MEASUREMENtS