4-128 User Math Menu
SR785 Dynamic Signal Analyzer
where r =
√
(x
2
+ y
2
) and
θ
= tan
-1
( y/x ). Sqrt computes all angles positive from 0. The
[X/(1-X)]( ) operator is generally used on real arguments only.
The jOmega( ) operator is simply j
ω
and zeroes the real part and fills the imaginary part
with the value of
ω
(2
π
• frequency) at each point in the array. The frequency is
determined by the span of the operand. A measurement operand (FFT(1) or Time(1))
uses the current frequency span. A Trace operand uses the span of the measurement
which is stored in the Trace.
FFT( ) is the windowed FFT operator. These operations switch the X axis type. The
current window chosen in the [Window] menu is used on the operand before the FFT.
FFTu( ) is the un-windowed FFT operator. The uniform window is always used. The
FFT( ) and FFTu( ) operators do not calibrate their results since their operands are not
necessarily input time records. To use a calibrated FFT, use the measurement operand
FFT(1) or FFT(2).
IFFT( ) is the inverse complex FFT operation. This operation switches the X axis type.
d/dx( ) is the derivative operator. The derivative is performed with respect to the X-axis
bin number, not the x-axis values. For example, to convert d/dx( ) to d/df( ) for a linear
frequency display, divide by the frequency spacing of the bins. In the case where the X-
axis is logarithmic, the function needs to correct for d(logx)/dx. The d/dx( ) operator
requires a smoothing aperture or window.
GrpDly( ) is the group delay operator. Group delay is simply d
θ
/d
ω
. Use [Display
Options]<d/dx Window> to set the aperture. This operator yields valid results for any
complex operand which has a frequency x-axis.
AWt( ) is the A-Weighting operator. This filter is a software version of the input A-
Weight filter. BWt( ) and CWt( ) are the software B-Weighting and C-Weighting
operators. The AWt( ), BWt( ), and CWt( ) operators should only be used on operands
with a frequency x-axis. All three filters conform to ANSI Standard S1.4-1983.
Function String
Move the cursor to the function equation window at the top of the screen. Use the knob
to move the highlighted cursor within the equation. <Delete> will delete the highlighted
term. <Operands> and <Operations> will either insert or replace at the cursor. Use
<Insert/Replace> to switch between insert and replace mode.
[<-] (Backspace) deletes the term before the cursor.
Insert/Replace
Toggle between insert and replace mode while editing a User Function equation.
If editing in insert mode, ‘Ins’ appears in the upper right corner of the edit window. If
editing in replace mode, ‘Rep’ appears.
Summary of Contents for SR785
Page 4: ...ii ...
Page 10: ...viii ...
Page 80: ...1 64 Exceedance Statistics ...
Page 158: ...2 78 Curve Fitting and Synthesis SR785 Dynamic Signal Analyzer ...
Page 536: ...5 136 Example Program SR785 Dynamic Signal Analyzer ...
