LeCroy 6000 SERIES, Operator'S Manual

Page: 358 / 409

Operator's Manual
356
ISSUED: October 2003 WR6K-OM-E Rev A
1. A noisy sine wave with a frequency of 3 MHz.
2. The first low-pass filter with 20 MHz edge frequency and 30
MHz transition region is applied.
3. A sparsed version of trace A.
4. A second low-pass filter with an edge frequency of 5 MHz and
a transition region width of 6 MHz is applied to the sparsed trace
in 3.
The last trace shows the zoomed signal, which was filtered by a multistage filtering method.
Notice that all high frequency noise components were removed.
CUSTOM FILTERS
Custom Filter Setup
If the standard filters provided with DFP2 are not sufficient for your needs, you can create filters
with virtually any characteristic, up to 2000 taps.
The required custom filter can be designed with a digital filter design or math package such as
MATLAB or Mathcad. The filter coefficients can then be loaded into the scope from an ASCII file.
The file consists of numbers separated by spaces, tabs, or carriage returns.
Note: Do not use commas as separators.
For a custom IIR filter there needs to be a multiple of 6. Each stage consists of 3 numbers for the
numerator polynomial followed by 3 numbers for the denominator polynomial. They are in the
order a b c where the polynomial is of the form: a + b * z
-1
+ c * z
-2
.
Example 1: Creating an FIR Filter Coefficient File Using Mathcad
N := 200 i := 0..N
sinx(x) := sin(x)/x