Average Function - Teledyne HDO9000 Operator's Manual

HDO9000 High Definition Oscilloscopes Operator's Manual

Average Function

Setting Up Averaging
To apply Continuous or Summed Averaging as a Math function:
1. Follow the usual steps to
submenu.
2. On the Average subdialog, choose Summed or Continuous.
3. Touch Sweeps and provide a value. The valid range is 1 to 1,000,000 sweeps.
Tip: To quickly set up Continuous Averaging (only), access the channel setup dialog (Cx) and
enter the number of sweeps to average in Averaging. The valid range is 1 to 1,000,000 sweeps.
Summed Averaging
Summed Averaging is the repeated addition, with equal weight, of successive source waveform
records. If a stable trigger is available, the resulting average has a random noise component lower
than that of a single-shot record. Whenever the maximum number of sweeps is reached, the
averaging process stops. In Summed averaging, you specify the number of acquisitions to be
averaged. The averaged data is updated at regular intervals.
An even larger number of records can be accumulated simply by changing the number in the dialog.
However, the other parameters must be left unchanged or a new averaging calculation will be started.
You can pause the averaging by changing the trigger mode from NORMAL/AUTO to STOP. The
instrument resumes averaging when you change the trigger mode back to NORMAL/AUTO.
You can reset the accumulated average by pushing the CLEAR SWEEPS button or by changing an
acquisition parameter such as input gain, offset, coupling, trigger condition, timebase, or bandwidth
limit. The number of current averaged waveforms of the function, or its zoom, is shown in the
acquisition status dialog. When summed averaging is performed, the display is updated at a reduced
rate to increase the averaging speed (points and events per second).
Continuous Averaging
Continuous Averaging, the default setting, is the repeated addition, with unequal weight, of successive
source waveforms. It is particularly useful for reducing noise on signals that drift very slowly in time
or amplitude. The most recently acquired waveform has more weight than all the previously acquired
ones: the continuous average is dominated by the statistical fluctuations of the most recently
acquired waveform. The weight of 'old' waveforms in the continuous average tends to zero (following
an exponential rule) at a rate that decreases as the weight increases.
You determine the importance of new data vs. old data by assigning a weighting factor. Continuous
averaging allows you to make adjustments to a system under test and to see the results
immediately. The formula for both summed and continuous averaging is:
110
set up a math
new average = (new data + weight * old average)/(weight + 1)
fuction, selecting Average from the Basic Math