LeCroy 9400A Manual page 21

Whenever a given data point of the new waveform
exceeds the existing data point of the accumulated
extrema waveform it replaces it. In this way the maxi-
mum and/or minimum envelope of all waveforms is
accumulated up to a maximum of 1,000,000 sweeps.
ARITHMETIC
WP01 also offers basic arithmetic operations such as
addition, subtraction, division, and multiplication.
These arithmetic functions can be performed on two
source waveforms on a point by point basis. Different
vertical gains and offsets of the two sources are auto-
matically taken into account. However, both source
waveforms must have the same time-base setting. The
first waveform may be multiplied by a constant factor
and offset by a constant.
MATHEMATICAL FUNCTIONS
Mathematical functions such as negation, square,
square root, integral and differentiation are performed
on a single source waveform. The waveform may be
multiplied by a constant factor and may be offset by a
constant. Arithmetical and mathematical functions may
be chained by using memory C and D.
SMOOTHING
WP01 provides two types of smoothing to decrease
signal noise of single transient acquisitions.
Mean value smoothing divides the acquired signal
into a chosen number of segments and then gener-
ates the smoothed waveform in which each displayed
point corresponds to the mean value of "n" points
contained in the corresponding segment. The number
of segments can be between 50 and 32000. Mean
value smoothing takes all digitized points on the
screen into account.
N-point smoothing applies a moving average of N
points symmetrically placed around each of the 50 to
32000 selected points for display.
Each selected point Yk is replaced in the smoothed
waveform by a processed point Y'k corresponding to:
(N-1)/2
Y' (k) =
C(n) Y(k+n)
n= -(N-1)/2
where, in case of a 3-point filter,
N -- 3; C 1 --- 1/4; C o -- 1/2; C 1 = 1/4
SPECIFICATIONS
SUMMATION AVERAGING
Number of sweeps: 10 to 1,000,000 can be selected
in a 1-2-5 sequence.
Number of points averaged over CH1, CH2:50 to
32000 in 10 steps.
Offset dithering: up to 6 LSBs may be chosen.
Artifact Rejection: ON/OFF
Theoretical signal-to-noise improvement achievable:
The number of points N can be selected to be 3, 5, 7
or 9.
In interleaved sampling mode, the averaging speed is
reduced as more signals are required to complete a
displayed waveform.
57 dB.
Vertical expansion: 10 times maximum.
Maximum sensitivity: 500/~V/div after vertical
expansion.
CONTINUOUS AVERAGING
Number of sweeps: infinite.
WAVEFORM ARITHMETIC
Addition, subtraction, multiplication, and ratio can be
performed on two live waveforms from CH1 and CH2,
or from stored waveforms in memories C, D and E.
E = CH1 - CH2
F = CH2 * D
F=CH1 +E
Example:
Weighting factors selectable: 1:1, 1:3, 1:7, 1:15, 1:31,
1:127.
Number of points averaged: 50 to 32000 in 10 steps.
Vertical expansion: 10 times maximum.
Maximum sensitivity: 500/JV/div after vertical
expansion.
AVERAGING SPEED
The figures below assume that the display time
Number of points processed: from 50 to 32000 can
be selected in 10 steps.
Multiplicative constants: from 0.01 to 9.99 can
be selected in steps of 0.01.
Additive constant: from - 9.99 to 9.99 divisions can
be selected in steps of 0.01.
Vertical expansion: 2 times maximum.
Typical execution time for 1250 points: 600 msec.
WAVEFORM FUNCTIONS
Integration, differentiation, square, square root,
between triggers is negligible:
record length summation
(= of points) (sweeps/sec)
32000 3
25000 4
12500 6
6250
13
2500 32
1250
51
625 73
250 100
125 112
50
118
negation (invert).
Examples: E=./' CH1 dt
F = - CH2
dD
E=
dt
Number of points processed: from 50 to 32000 can
be selected in 10 steps.
Multiplicative constants: from 0.01 to 9.99 can be
selected in steps of 0.01.
Additive constant: from -9.99 divisions to 9.99
divisions can be selected in steps of 0.01.