could it be street lights, if so what can i do

[#1]

You wouldn't have a radio that can tune to 600kHz unless you were in the business / radio engineering  ;).
Many scanners have 600kHz and it would be Amplitude Modulation - or SSB, single sideband

[#2]

I'll go and hunt out an old radio and have a check later, have an interview to go to 1st.
podman

[#3]

Quote from: Mal08

You wouldn't have a radio that can tune to 600kHz unless you were in the business / radio engineering  ;).

Er, medium wave is 522 - 1611 kHz, as found on any domestic tranny.

[#4]

sorry meant to say 600kHz radio with Frequency Mod 🙂

[#5]

I don't think you get any FM stations at 600 KHz 
Anyway, impulse noise will have a major AM component.
Doesn't the ADSL signal go up to 1100 KHz anyway?

[#6]

It does indeed

[#7]

It's a clever modulation system
http://en.wikipedia.org/wiki/ADSL

[#8]

Finally managed to get a graph of my router stats. Before the street lights come on my down stream is 11 or 12 occasionally 10.
Podman