358 Appendix E High Resolution Digitizing With the 3458A
Errors in Measurements
The flexibility of the 3458A helps you avoid or compensate for many of the
measurement errors that can occur in the digitizing process. Errors associated with
digitizing can be grouped by their amplitude error and time error contributions to
the total error in the measurement. For dynamic signals, time errors result in
amplitude error. Fortunately, most time dependent measurements are differential
and any absolute timing errors are calibrated out of the measurement. A close look
at the block diagram of the 3458A reveals the sources of error in the measurement,
summarized in Figure 60.
Broadly speaking, errors that creep into digitizing measurements are evident in
both the amplitude and time axes.
For amplitude, the errors are:
1. Quantization error
2. Missing code
3. Non-linearity
4. Noise
5. Bandwidth
6. Amplitude accuracy
On the time axes, the error factors are:
1. Timebase reference jitter
2. Trigger uncertainty
3. Trigger accuracy
Figure 59. Example of
results generated using
the Wave Form Analysis
Library.
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