What situations could cause a false alarm?
Personal protection requires early alarming in case of dangerous field conditions. Therefor long averaging times (e.g. 6 minutes) are not appropriate. So the monitor will detect short peaks exceeding the limit which triggers an alarm. Also the problem of distance is important. With the personal monitor you are often much closer to a radiation source as with a measuring instrument. Because of the quadratic or cubic relationship between distance and field strength you have very close to the antenna a high field strength which is sometimes over the limits (e.g. mobile phone, TV-Sets, displays …).
