Outputs, offsets and expands – SRS Labs SR850 User Manual

Page 27

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6.

Connect the DVM to the X output on the rear
panel.

7.

Connect the DVM to the CH1 output on the
front panel again.

Press <Expand>

Press [1] [ENTER]

Press <Offset>

Press [0] [ENTER]

The highlighted EXPD indicator turns on at the
bottom left of the top display to indicate that the
displayed trace is affected by an expand.

The CH1 output is
(X/Sensitivity - Offset)xExpandx10V. In this case,
the output voltage is

CH1 Out = (0.5/1.0 - 0.4)x10x10V = 10V

The expand allows the output gain to be increased
by up to 256. The output voltage is limited to
10.9 V and any output which tries to be greater will
turn on the OUTPT overload indicator at the
bottom left of the screen.

With offset and expand, the output voltage gain
and offset can be programmed to provide control
of feedback signals with the proper bias and gain
for a variety of situations.

Offsets do add and subtract from the displayed
values while expand increases the resolution of
the display.

The X and Y outputs on the rear panel always pro-
vide voltages proportional to X and Y (with offset
and expand). The X output voltage should be
10 V, just like the CH1 output.

The front panel outputs can be configured to
output different traces quantities while the rear
panel outputs always output X and Y.

Outputs proportional to X and Y (rear panel, CH1
or CH2) have 100 kHz of bandwidth. The CH1 and
CH2 outputs, when configured to be proportional
to R,

θ

, or a trace (even a trace defined as X or Y)

are updated at 512 Hz and have a 200 Hz band-
width. It is important to keep this in mind if you use
very short time constants.

Let's change CH1 to a trace.

First, set the X expand back to 1.

Set the X offset back to 0.0%.

X Should be 0.500 V again and the CH1 output

Outputs, Offsets and Expands

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