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.
The frequency is the number of waves that pass a point in space during any time interval, usually one second. We measure it in units of cycles (waves) per second, or hertz. The frequency of visible light is referred to as color, and ranges from 430 trillion hertz, seen as red, to 750 trillion hertz, seen as violet.