Throughout the testing time frame, the 1027 records a measurement once every hour.  It stores the measurements in its memory.  When the data is transferred at the end of the test, the software uses all of the measurements to conclude and average reading for the entire test.

 According to the EPA protocol, and the manufacturers recommendations, I have my radon monitors calibrated once a year by Sun Nuclear, the manufacturer.  They submit the monitor to a chamber of known radon content and test it's accuracy.  They then make any necissary adjustment to assure that it is in line with standards.  I currently have two CRM's availible for duty.  I have posted their calibration reports for public viewing.  Links to those reports are below.

Sun Nuclear Model 1027 - Serial # 3385182

Sun Nuclear Model 1027 - Serial # 1860189 

Sun Nuclear Model 1027 - Serial # 35531014

Sun Nuclear Model 1027 - Serial # 35531016

Now and then, circumstances such as no electrical power might require a different method be used to test for radon in air.  In these cases I may use Radelec E-Perm chambers.  These devices are also reliable.  They are delivered to a lab at the end of the test.  The lab calculates the results and submits a report which I then forward to the interested party.