At a recent checkup, I was shocked: Even though I was eating foods rich in saturated fat and a seemingly more indulgent diet, my total cholesterol was down 10 points, my bad LDL cholesterol was stellar, and my good HDL was the highest it's ever been.
As the frequency of the signal to be measured increases to approach the frequency of the source frequency, measurement error increases. To improve the accuracy of the frequency measurement for higher unknown frequency, we can use this second measurement method, count number of pulses in known time.
Frequency is a measure of how many times something moves back and forth. A swing, a pendulum, a leg of a walking person all have a frequency. All those things start at one place, move, and come back to the same position that they started. This moving and coming back is one vibration. The faster something vibrates, the more frequency that something has.