1) Point to point step calibration, the sensitivity is checked at selected frequencies and a calibration curve is drawn out.

2) Is called continuous method also known as Full Frequency Sweep or B&K White Noise Method, as implied sensitivity is checked over the full frequency range of the sensor. This is about a 15 minute procedure and a full frequency graph is printed with the calibration certificate.

Below the single calibration only checks the sensitivity at one (1) frequency 100 Hz. The green arrows represent the optimal range of the accelerometer. That is the frequency range you are suppose to take your vibration measurements. If you do not check the sensitivity over the full range of the accelerometer you do not know if it is performing to specification. That is why you should always request a continuous calibration certificate when you buy an accelerometer.