HP E42 manual Sources of Measurement Error, 36.±1 Count Ambiguity

Model 5328A

Theory of Operation

Figure 4-5,Synchronizer Operation with Time Interval Averaging

4-33. There are occasional situations where time interval averaging cannot be performed on a periodic signal. This problem occurs when the input time interval repetition rate is synchro- nous with the internal clock.

4-34.SOURCES OF MEASUREMENT ERROR

4-35. The major sources of measurement error are the ±1 count ambiguity, the time base error and trigger error. These are discussed in the following paragraphs.

4-36.±1 Count Ambiguity

4-37. Since the signal input to the main gate of the counter and the clock input are not coherent, an inherent ±1 count ambiguity exists in the count accumulated in the decade counting assem- blies. This is illustrated by Figure 4-6.

Figure 4-6.±1 Count Ambiguity

NOTE

The main gate is open for the same time, tm, in both cases. incoher- ence between the clock and the input signal can result in two different counts which for this example is one for case A and two for case B.

4-5