I'm talking about one of these: http://www.eldan.biz/emall/shops/1903/45983-tb-Automess-dose%20rate%20meters.jpg [Broken] The use a Geiger-Muller gas chamber which can only detect when A UNIT of gamma or beta radiation (or alpha if you have a really tiny window) goes through, but it says nothing about the energy or the origin of the pulse. So, all it measures is (compensating for the dead time) counts/sec. Yet the output is in units of uSv/h or mR/h. From what i know, one needs to know the source constant h to go from cps to dose, using: D = h*A / r^2 And to determine the source constant h, one needs to know the energy and type of incoming radiation. The GM-counter obviously does not have this information, so how does it calculate the dose rate?