I have that same type problem.  I am in 460 mhz range.  I bought a directional antenna a handheld radio to trace noise.  From Leeds I drove towards Rugby and gave up on locating the problem but was told that is one way to really find where is is from. That was a few years ago. I should try to find it again if I ever had more time.  It is not all the time but sounds like transmissions with data being sent.
Good luck. 
I use cell phones more so get by with noise.
You can go to FCC and search frequencies and who owns them.  May help.