Im not sure I understand your questionThe question is not really clear but I will briefly write about radiological survey instruments..maybe that will help.
Radiological survey instruments are used to determine exposure rates,infact it is the most effective method for determining exposure rates.
The radiological survey instrument consist of various parts.It has a chamber in which nuclear radiation us detected,yielding an electric pulse or current,and electronic circuitry which converts the current into a meaningful readout.
Most survey instruments are portable, and fairly easy to maintain in operational condition .Most survey instruments maintained for emergency management are powered by standard Dcell batteries.That is why they are portable and fairly easy to maintain.
If you want to determine exposure rate with a survey instruments follow the operational instruction for that instrument.The procedure varies for different detectors