# Calculation method of 53131A measurement accuracy and error of measuring 1Hz signal frequency

## Calculation method of 53131A measurement accuracy and error of measuring 1Hz signal frequency

### Troubleshooting (FAQ)

### Summary

Explain how to calculate 53131A measurement accuracy and error of measuring 1Hz signal frequency.### Question

How to calculate 53131A measurement accuracy and error of measuring 1Hz signal frequency?### Answer

Generally speaking, users can do it using the instrument’s standard time base, medium-stability time base (Option 001), or high-stability time base (recommended) and the following instrument settings:Gate Time: 1 second

Auto Trigger: off

Level: 50%

By selecting “Assumptions” you can view the assumptions the calculator uses in its calculations. The first assumption listed is the total measurement error equation:

Measurement Error = Systematic Uncertainty + 2 * RMS Resolution

Because the time base error term in the Systematic Uncertainty equation is dominant (much larger than the other terms in the equation) and much larger than the RMS resolution, the measurement error is effectively, the time base error. By selecting “Details” as shown above, you can see the calculated time base error. For the medium-stability time base selected, the time base error , thus the measurement error (accuracy) is 3.6 ppm. For comparison, when calculating the accuracy of measuring a 1 Hz signal using the standard time base and high-stability time base, you can get the following:

Standard Time Base: 8.6 ppm

High-Stability Time Base: 0.1825 ppm