Bird Diagnostic System
32
Averaging
The BDS offers two types of data averaging for Standard Tracking Mode: Simple (Fixed) or Moving. Both averaging
modes will reduce signal-to-noise ratio in a measurement. Averaging is performed in the receiver.
Figure 33 Averaging Dialog
A simple average will take a number of measurements and then compute and report the average value after the
number of measurements has been sampled. This averaging mode will decrease the data update rate by the number
of averages requested.
Example -
If the data update rate for 1 measurement dataset is 10ms, then it will take about 40ms to
average 4 measurements and produce the result. A user can average up to 16 measurements using
Simple averaging.
The Moving average mode averages data over time using a sliding filter window. The average window size is
specified as a power of 2 ranging from 2 to 128 measurements.
The difference between Moving and Simple averaging is that the moving average doesn’t wait for the buffer to fill
before computing a result, it simply adds a new measurement to the buffer and computes and reports the result. It
removes the oldest measurement if the buffer is full before adding the new measurement. This provides little impact
to the data update rate, depending on the measurement set.
The “V/I Noise Threshold” parameter is used to determine when to clear the filter buffer – when the signal (voltage
or current) exceeds this threshold the buffer is cleared to provide a fast response to the measurement system.
De-embedding
De-embedding is used to mathematically rotate the measurement plane from the center of the BDS sensor toward
either the load or the signal source. In doing so, it adjusts measurements made by BDS sensor in order to get a
reading at a different segment of a line section.
Figure 34 De-embedding Dialog
The de-embedding algorithm accounts for losses in the RF delivery system.
The de-embedding options allow users flexibility to enter segment parameters in different formats to match
segment spec or data sheets.
Line section impedance is entered as either inductance and capacitance or Z0 in Ohms.
Dielectric is entered as either propagation velocity as a fraction of the speed of speed of light or in Er.
Loss can be entered as Ohms, dB, or Nepers.
