All types of measurements made by the device are based on counting the number of pulses from detector over a certain period of time for the assessment of average frequency of these pulses. Calculated average frequency is converted to value of ambient dose intensity or to value of flux density of the particles and is displayed on a screen of device.
As well the device evaluates and displays statistical error of current measurement. This error appears due to properties of randomness, which inherent to all types of radioactive decay. At the beginning of measurement statistical error of is high, and readings are changing rapidly. With increasing of measurement time the statistical error is reducing, and the readings are becoming more stable. In such a manner, the longer measurement is performed, the more statistically reliable result is obtained.
Also there is an important additional condition of obtaining reliable results. Radiation level in area of the detector shouldn’t change significantly during the measurement. It is possible, for example, when device and radiation source are motionless, or if radiation level at the motion path of the device is everywhere approximately the same.