PPM (parts per million) is a unit of measurement that describes the frequency stability of a crystal oscillator. Hz (Hertz) is the unit of frequency, representing the number of cycles per second.
The formula to convert PPM to Hz is:
\[ \text{Frequency Variation (Hz)} = \frac{\text{Oscillation Frequency (MHz)} \times 10^6 \times \text{PPM}}{10^6} \]
Consider an oscillator with a frequency of 10 MHz and a stability of 5 PPM:
Using the formula:
\[ \text{Frequency Variation (Hz)} = \frac{10 \times 10^6 \times 5}{10^6} = 50 \text{ Hz} \]
This means the frequency variation is 50 Hz.