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SR71BB — Sun, 28 Nov 2021 19:36:23 GMT

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 18:54:23 GMT

You said that "The noise level on such a short line seems to be very high."

Do you mean that you are hearing noise on voice calls? In which case have you done a quiet line test by dialling 17070?

I'm just wondering if you are confusing "noise level" with the noise margin figures that you quoted. For noise margin, the higher the figures the better, (generally). Your figures of "15.5 / 12.7" are very good.

Noise margin is basically the difference between the wanted broadband signal level and the unwanted noise. If the noise margin is too low, then the hub can have difficulty in differentiating between wanted signal and unwanted noise, leading to errors and lower speeds.

SR71BB — Sun, 28 Nov 2021 19:36:42 GMT

SR71BB — Sun, 28 Nov 2021 19:36:54 GMT

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 19:08:28 GMT

For the downstream at least, the minimum desirable is around 6dB I believe? I have also been told that this depends on the manufacturer of the equipment in the serving cabinet, and can potentially be as low as 3dB and still be satisfactory, (noted that you may be connected directly to the exchange).

For comparison, I am 50 metres, (by cable), from my cabinet and my noise margin figures are 16.0 / 10.6

SNR and Noise Margin is basically the just different names for the same thing - the difference between the noise floor and the wanted signal. As I said before, generally more is better for this figure, though provided it never drops below the minimum there is nothing to be gained. ie my current downstream measurement is 10.6dB and AFAIK it could go down to say 4dB and my speed and connection would be unaffected(?).

SR71BB — Sun, 28 Nov 2021 19:37:23 GMT

SR71BB — Sun, 28 Nov 2021 19:37:36 GMT

Re: Random disconnects on a new connection

imjolly — Sun, 28 Nov 2021 19:35:56 GMT

On FTTC you are not connected to the exchange but to a street cabinet. However I think in your case you originally had EO (exchange only) line and ould not get FTTC. OPENREACH then built cabinet outside exchange which allowed connection like yours to get FTTC.

Your noise margin is high because your attainable being so close to cabinet is far higher than your connection speed of 80mb. This will not reduce and stands you in good stead should FTTC ever allow higher connection speed.

SNR IS signal to noise ration which is not the same as noise margin which is what the routers show.

Are you on digital voice as that would explain why dslchecker does not recognise your phone number

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 19:42:17 GMT

@imjolly

"SNR IS signal to noise ration which is not the same as noise margin which is what the routers show."

For my understanding, can you explain the difference between Signal to Noise Ratio and Noise Margin please?

Re: Random disconnects on a new connection

licquorice — Sun, 28 Nov 2021 19:58:00 GMT

Signal to noise ratio is exactly that, the ratio of signal level to noise level. SNR margin is the amount of margin the signal has over the noise level.

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 20:08:14 GMT

@licquorice

I understand that, so what is "Noise Margin" measuring if not that?

Re: Random disconnects on a new connection

gg30340 — Sun, 28 Nov 2021 20:10:09 GMT

Any one have any idea why the OP has deleted all his posts?

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 20:14:50 GMT

@licquorice

I'm not sure if my previous post made sense. I'm asking what the difference between Signal to Noise Ratio (SNR), and SNR Margin is please?

Re: Random disconnects on a new connection

imjolly — Sun, 28 Nov 2021 20:17:50 GMT

https://kitz.co.uk/adsl/linestats.htm#SNR

Re: Random disconnects on a new connection

licquorice — Sun, 28 Nov 2021 20:49:31 GMT

@gg30340 wrote:

Any one have any idea why the OP has deleted all his posts?

Nope

Re: Random disconnects on a new connection

Keith_Beddoe — Sun, 28 Nov 2021 21:01:34 GMT

@licquorice wrote:

@gg30340 wrote:

Any one have any idea why the OP has deleted all his posts?

Nope

This is the content of the last post by @SR71BB Deleting the posts the way its been done, seems to have upset the forum index, as there are posts with no subject.

"Another test.

Jitter this time 26.4 ms

Maybe I should delete this thread and restart it but put greater emphasis on the jitter.

https://www.netmeter.co.uk/ping-test/202147-72090-1654.html

Posted with device: google_chrome_96

Re: Random disconnects on a new connection

licquorice — Sun, 28 Nov 2021 21:14:55 GMT

With all due respect @@Keith_Beddoe I'm not sure it is right to repost items that somebody has decided they no longer wish to be publicly viewable.

Re: Random disconnects on a new connection

Anonymous — Sun, 28 Nov 2021 21:31:54 GMT

@imjolly

Thanks for the link - very interesting.

My SmartHub2 currently says that my downstream Noise Margin is 10.9dB. I have previously been advised on these forums that my cabinet is of a type that only requires 3dB, would that have been 3dB SNR or Noise Margin? ie could I lose nearly 11dB and still maintain my connection speed, or only 7.9dB before there would be problems?

Cabinet 50 on Bradwell Abbey exchange.

Re: Random disconnects on a new connection

imjolly — Sun, 28 Nov 2021 21:45:34 GMT

It is noise margin the routers show not SNR. The normal noise margin is 6db but should you have an attainable speed in excess of the say 80mb max connection speed then the noise margin will be higher than the norm. The bigger the difference between attainable and the actual the higher the noise margin .

The DLM can if on Huawei cab activate G.INP reducing noise margin down to 3db giving an increase in connection speed. Obviously not higher than your package max 55/80mb

Re: Random disconnects on a new connection

licquorice — Sun, 28 Nov 2021 21:46:52 GMT

Margin.

You have to look at everything together, you can't look at one parameter in isolation.

Target noise margin is 3dB for most cabinets but if you are very close to the cabinet or have a capped service, noise margin will be high.