Hi all. I am new to the board. Just recently decided to get a new scanner and found this site in my research. I've read all about the different types of scanners these days, and I'm pretty familiar with an old school conventional scanner. But I still seem to be a bit fuzzy on this whole trunking conceept. Mainly because when I look at London (40741) in the database it lists some trunking systems, and then it lists a bunch of frequencies. Can anyone help me a bit? I'm trying to decide between a GRE PSR-100 or a PSR-300. Do I NEED the PSR-300?