Is this noise margin variation normal?

Sample from RouterStats log.

Sun 06 Dec 2009 09:09:48, Noise Margin= 12.0, Sync Speed= 6368, 1 day, 0:46:00

Sun 06 Dec 2009 19:30:13, Noise Margin= 3.5, Sync Speed= 6368, 1 day, 11:06:23

Router ST585 v 6.2.17.5. d/s attenuation 40dB. Remained synced all day.

No; a margin variation of 8.5dB (at the same sync speed) is not normal.

Have you tried the usual tricks (removing the ring wire, connecting the router into the 'test' socket, etc.)?

Yes it is.

Why do you think that the noise margin should not vary?

In reply to a post by adebov:

No; a margin variation of 8.5dB (at the same sync speed) is not normal.

Have you tried the usual tricks (removing the ring wire, connecting the router into the 'test' socket, etc.)?

Filter faceplate at master socket, connected to router 6 feet away.

BTW stats this morning

Mon 07 Dec 2009 08:14:19, Noise Margin= 11.0, Sync Speed= 6368, 1 day, 23:50:28

Yes, it is normal. Once it goes dark numerous factors come into play and the background noise will increase. It can be anything from 3dB to 15 dB (or maybe even more).

If you resync now with a lower margin, this evening it will loose sync and reconnect at a lower speed again. Just leave as is.

If you could stop the rotation of the earth and orbiting around the sun then you could stabilise the margin.

In reply to a post by MHC:

If you could stop the rotation of the earth and orbiting around the sun then you could stabilise the margin.

I'll work on it

Actually, I am amazed it stays synced at such a low margin!

If SNR Margin is used correctly it should stay sync'd at 0dB. But who knows with router manufacturers?

A router should sync at a specified SNR which is rarely stated - the MARGIN is the spare available.

OK thanks.

btw: now have a G1, a GF1, 14-45, 45-200 and 20mm f/1.7 pancake

In reply to a post by MHC:

Yes, it is normal. Once it goes dark numerous factors come into play and the background noise will increase. It can be anything from 3dB to 15 dB (or maybe even more).

If you resync now with a lower margin, this evening it will loose sync and reconnect at a lower speed again. Just leave as is.

If you could stop the rotation of the earth and orbiting around the sun then you could stabilise the margin.

Variations of more than 6dB usually indicate a split pair, or bad wiring on the customer's side of the master socket.

At >6Mb a split pair is unlikely.

Mine can vary by up to 12dB - and that is irrespective of wiring and I know of others where it can be as low as 1 dB variation.