I'm not a radio scanner hobbyist, but I thought
you folks might be able to help.

I have an 802.11b wireless network in my house;
the access point is a Linksys DWL-1000AP. I also
have a pair of baby monitors, made by Safety 1st.

I believe the wlan operates at a frequency around
2.4 GHz, and the baby monitor at 49.8 MHz.

I suddenly noticed considerable degradation in
the performance of both of these devices. They
continue to work, but the network connection
is very spotty, and the baby monitor has lots
of noise.

Questions:

Is there one thing (possibly at neighbor's
house, I live in a townhouse) that could simultaneously
disrupt both of these devices?

Is there an inexpensive tool (scanner?) that can
search an arbitrary range of frequencies and report
the presence of signals and their relative strengths?
I don't have a need to listen to signal per se, more
interested in identifying it.

More generally: how does one approach the problem
of troubleshooting radio interference?

thanks for any information,
-usman