[Al Skierkiewicz]

Erik,
I posted a few of the rules because of the statement that he intended this to be used at a First event. To follow up, interference can come from the mixture of a variety of signals. Most often these are on frequency or harmonics (sub harmonics too) and in general the second and third harmonics are the most incipient. However, anything that can mix with 900 MHz and harmonics can produce a signal on 2.4GHz known as intermod distortion. Second harmonic mixing with a 450 Mhz business band/police radio might produce a signal that swamps communication at 2.4GHz