You may wish to consider SDR# with a dongle or better yet an airspy, and install the frequency scanner plugin. With an airspy
you can scan the entire milair band in about a second. Prolly takes 2.5 seconds or so with a dongle. This will allow you to find whats
actually in use around you. 225-380mhz. There is a split in there that is FM sattelites, but you prolly won't hear much of that by accident (signals are pretty weak without the right antenna). It's a needed in a haystack problem, you'll never know how much there is around you til you can monitor it all almost at once, such as with the above mentioned setup.