Sample clocked buffered point frequency measurements can either be a single frequency measurement or an average between sample clocks. For buffered frequency, averaging is enabled by default.

A sample clocked buffered frequency measurement with averaging enabled uses the embedded counter and a sample clock to perform a frequency measurement. For each sample clock period, the embedded counter counts the signal-to-measure (fx) and the primary counter counts the internal time-base of a known frequency (fk). Suppose T1 is the number of ticks of the unknown signal counted between sample clocks and T2 is the number of ticks counted of the known timebase as shown in the following figure. The frequency measured is:

Next, route the Counter 0 Output signal to the input of Counter 1. You can route a signal of known frequency (fk) to the Counter 1 timebase. Configure Counter 1 to perform a single pulse-width measurement. Suppose the result is that the pulse width is J periods of the fk clock.

When averaging is disabled, the frequency measurement returns the frequency of the pulse just before the sample clock. This single measurement is a single frequency measurement and is not an average between clocks as shown in the following figure.

With sample clocked frequency measurements, ensure that the frequency to measure is twice as fast as the sample clock to prevent a measurement overflow.