The Radio Check If you listen you can hear it Control will announce the intention of carrying out a radio check a few minutes before it takes place - be ready! Your reply will be:    (your callsign) in position, SS1, Post 4, reading you 5s That is assuming you are on stage 1 at post 4! Substitute as necessary! The "reading you 5s" bit is a way of measuring Control's signal strength at your position. Measured from 1 to 5 where 1 is dim and distant, probably with a lot of background noise, through to 5 which is perfect. Remember, when you are listening before the radio check moving your vehicle just 12 inches can be the difference between receiving control at 1 and receiving at 5. Trees, vehicles, hills, buildings all redirect the radio waves. All you have to do is find those radio waves! If you are start or finish radio use the radio check to tell Control the state of readiness of the Start and Finish timing crews.