Whether its a proof or not. the point is there were changes to the SNRM which did change my sync. I did speed tests and there was a 6Mb increase.

Speed Tests

Edited by sohail2k (Wed 01-Feb-17 17:15:02)

Understood.

The point I was making back is that there are other reasons for what you have seen, and have been for a long time before this trial existed.

The first part of analysis now is to figure out which case you are following...

In reply to a post by BatBoy:

Unfortunately, my modem has no knowledge of the target SNRM and so my attainable is calculated as being a lot less than my actual

Interesting. I wonder why some seem to know, and some do not?

I can only comment on mine obviously. What are these other ones that seem to know?

In reply to a post by WWWombat:

Understood.

The point I was making back is that there are other reasons for what you have seen, and have been for a long time before this trial existed.

The first part of analysis now is to figure out which case you are following...

You could be right but I am not aware of any other reason which could have lowered the SNRM. This is the first time I have see it and it was actually below 3db. Should have taken the telnet stats. If it happens next time I'll do that.

Just to mention that I live in Reading (Earley area), and the exchange is not on the list of test exchanges (someone posted a list on these forums). So not sure how we take these results.

I'll try to do a resync tonight or early tomorrow morning (15 min power cycle method).

Luckily the monitoring app I use tells me the SNRM when my modem resyncs, so I know the target is 5dB.

In reply to a post by sohail2k:

I don't have the raw stats at the moment. But if you see screenshots - it says GINP enabled. INP 48. Interleaving On (8). I had G.INP enabled for a long time. Clearly I had 3db profile enabled for a couple of days with G.INP enabled.

Sorry, I'm not particularly familiar with that layout and didn't see the G.INP line above the table. I was looking in the table .

As for telnet stats, that's what I'm looking for in relation to your current sync - I see in a later post you say you will be getting those .

In reply to a post by sohail2k:

but I am not aware of any other reason which could have lowered the SNRM.

When you see the SNRM value in the modem stats, it reflects the current actual situation, not the target. The actual value varies second-by-second, depending on the noise interference encountered. Noise can change, so SNRM can change too.

A low SNRM can be seen with a normal sync speed, for example, after a new subscriber is activated. In this case, the attainable speed will be lower than the current, normal speed. Next time there is a resync, the sync speed will likely be reduced.

A low SNRM can be seen with a high sync speed, for example, after a DSLAM has been restarted, or the area has had a power cut. In this case, modems can start with a 6dB target and a higher-than-normal speed but, as other subscribers start up in parallel, the SNRM value will drop. In this case, the attainable speed will be lower than the current (excessive) speed, but will be around the normal speed for the line. Next time there is a resync, the sync speed will return back down to normal.

In your case, it looks more like the latter has happened. The attainable speed (in the screenshot) was much lower than the actual speed. A resync put everything back to normal.

Easy - you record a copy of the figure at the time of training, either by being passed it, or inference from the first sample after sync negotiation has completed.

Not sure that attainable is going to be reliable, as many will be based on the old relatively standard 6dB margin being fixed into the code for the maths

That's what I think too, mine is apparently using the default of 6 to do the calculation for the attainable.
Which ones are using the actual target margin?