Sure, but it did open my eyes to the possibilities-I think the laptop idea is probably the most simple way of checking.
The only problem with the laptop idea is catch-22. You can't find a sweet spot unless you can see it first. It's like scanning your TV for available channels, if it can't be seen, you will not be able to tune to it later.
Only a spectrum analyzer will work, it see all signal, even the weak ones.