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User manual

ManualsBrandsTELEDYNE LECROY ManualsLaboratory Test EquipmentDigital 350 MHz 2 GSa/s 10 Mpts 8 Bit Digital storage (DSO)
71727374757677787980
Math and Measure
However, by setting a Sweeps value, you establish a fixed weight that is assigned to the old average once
the number of sweeps is reached. For example, for a sweeps (weight) value of 4:
Sweep New Average =
1 (no old average yet) (new data +0 * old average)/(0 + 1) = new data only
2 (new data + 1*old average)/(1 + 1) = 1/2 new data +1/2 old average
3 (new data + 2 * old average)/(2 + 1) = 1/3 new data + 2/3 old average
4 (new data + 3 * old average)/(3 + 1) = 1/4 new data + 3/4 old average
5 (new data + 4 * old average)/(4 + 1) = 1/5 new data + 4/5 old average
6 (new data + 4 * old average)/(4 + 1) = 1/5 new data + 4/5 old average
7 (new data + 4 * old average)/(4 + 1) = 1/5 new data + 4/5 old average
In this way, for sweeps > 4 the importance of the old average begins to decrease exponentially.
Note: The number of sweeps used to compute the average is displayed at the bottom of the trace
descriptor box.
ERes Function
ERes (Enhanced Resolution) filtering increases vertical resolution, allowing you to distinguish closely
spaced voltage levels. The instrument's ERes function is similar to smoothing the signal with a simple,
moving-average filter. However, it is more efficient concerning bandwidth and pass-band filtering.
Use ERes:
l On single-shot acquisitions, or where the data record is slowly repetitive (cases where you cannot use
averaging).
l To reduce noise on noticeably noisy signals when you do not need to perform noise measurements.
l When performing high-precision voltage measurements (e.g., zooming with high vertical gain).
Setting Up ERes
To apply ERes as a Math function:
1. Follow the usual steps to set up a math function, selecting Eres from the Filter submenu.
2. Touch the Trace On checkbox.
3. On the Eres subdialog, select the number of bits of improvement from the pop-up menu.
How the Instrument Enhances Resolution
The instrument's enhanced resolution feature improves vertical resolution by a fixed amount for each
filter. This real increase in resolution occurs whether or not the signal is noisy, or whether it is single-shot or
repetitive. The signal-to-noise ratio (SNR) improvement depends on the form of the noise in the original
signal. The enhanced resolution filtering decreases the bandwidth of the signal, filtering out some of the
noise.
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