Originally Posted by Keef
out here in rural Suffolk I can hear gently warbling carriers all over the 430-440 MHz band. They are coming in off the aerial (removing it removes them) but are clearly not amateur. They aren't as rough and unstable as SMPS noise, but as to what they are...
You will find that the range of frequencies in question are used by a whole host of users. It is a shared band with radio amateurs. Remotes for car keys use 433.92Mhz +/- 100Khz in addition to that I seem to recall that building sites use various spot frequencies for cranes. That is something to do with making sure that jibs do not collide. The list is fairly long as to other users of 430-440 Mhz.
Astral