Odd noise syndrome

I came back to this house after having been away for 3 weeks to find that I now have a regularly occurring pattern of noise which wasn't there previously.
There are bursts at hourly intervals throughout the day, and the only variation I've seen is a later start on Saturday morning - apart from that it seems to be persistent.
I haven't changed equipment, to give rise to this new pattern, and can so far spot nothing to account for it.
I'm not noticing problems with the internet link apart from this - browsing and so on seem unaffected.

The pics linked to are from routerstats reading from my main Netgear DG834G.
pic1
pic2
pic3
pic4



I'm not sure what to try.

Hourly intervals suggest a timer kicking in somewhere and the later Saturday start suggests that it's from a domestic source. If there's nothing in your premises that's timed hourly, suspect a neighbour.
Over what time periods does the interference occur?

Edited by Deadbeat (Sun 21-Oct-12 12:30:49)

Someone's central heating perhaps?

(Which order are those graphs please? They seem to be random. Makes it hard to follow a timetrack).

It could be but central heating switching tends to be pretty random after the initial switch on.

And 4:50am is quite an unusual time for central heating.

In reply to a post by Oliver341:

And 4:50am is quite an unusual time for central heating.

Not for my missus!

The time order is 1,4,3,2 - they got shuffled when transferring to photobucket (I'm not familiar with its foibles)

I'd considered candidates like central heating - but ruled it out as I'd never seen this before. It has to be something newly installed, and probably noiseless, as otherwise either I or my wife would have noticed it happening during the night.

Is there any chance of it being a PSU, and if so can I find out whether its mains-borne?

Edited by dandnsmith (Sun 21-Oct-12 14:00:53)

In reply to a post by Deadbeat:

Not for my missus!

15 tog duvet for christmas?

15 ton might just do it!