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[burakkucat]

Slightly offtopic, but I wonder if anyone could explain to me how to correctly read my Hlog? It appears to be a stable curve for most tones, but upon reaching tone 2750, there are many spikes.

Reading it from low frequency to high frequency (left to right), you have usable US (green), DS (red), US (green) and DS (red). At the frequencies of the next US band, the signal is so degraded (due to line length, conductor material (aluminium), etc) that it drops to the "no signal present" value (-94.6 dB). At the following DS band (even higher frequencies) there is an indication of some signal "getting through" but it is essentially unusable (the "ragged tail" of the plot).

I would also like to suggest that you consider the the bands in the "Discovery Phase" and in the "Medley Phase" (a.k.a. "showtime") of your pbParams information.

[Dave2150]

Slightly offtopic, but I wonder if anyone could explain to me how to correctly read my Hlog? It appears to be a stable curve for most tones, but upon reaching tone 2750, there are many spikes.

Reading it from low frequency to high frequency (left to right), you have usable US (green), DS (red), US (green) and DS (red). At the frequencies of the next US band, the signal is so degraded (due to line length, conductor material (aluminium), etc) that it drops to the "no signal present" value (-94.6 dB). At the following DS band (even higher frequencies) there is an indication of some signal "getting through" but it is essentially unusable (the "ragged tail" of the plot).

I would also like to suggest that you consider the the bands in the "Discovery Phase" and in the "Medley Phase" (a.k.a. "showtime") of your pbParams information.

Thanks for this wonderful explanation

[Dave2150]

Hi there,

My line synced a little higher again today! Now syncing at 36,194Kbps.

I'm a little confused with my speed tests - I'm only getting 33.85Mbps -



IP profile result:


Am I right in thinking this result is a little low, considering my sync rate and that I have no interleaving on my line (G.INP active).

I've restarted my BT HH5B a few times to create a new PPP session, with the same result.

Many thanks for any help

[WWWombat]

I think the IP Profile is right - 96.7% of 36,194 = 34,999

Then losing about 2Mbps on the speedtest overheads also seems about right. It could, possibly, be a tiny tad higher, but not a lot.

[Dave2150]

I think the IP Profile is right - 96.7% of 36,194 = 34,999

Then losing about 2Mbps on the speedtest overheads also seems about right. It could, possibly, be a tiny tad higher, but not a lot.

Thanks for the reply. I wasn't aware of this "96.7%" reduction, thanks for informing me. I've read http://www.kitz.co.uk/adsl/IPprofile.htm but I still don't understand the reason for effectively reducing each line's bandwidth by 3.3%.

Why exactly is this needed? I understand the need for an IP Profile, but surely it would be best for us if it simply set itself to the current sync speeds etc?

[Chrysalis]

BT wholesale network cannot handle queued packets so the IP profile gets set to slightly below I think what the natural flow of traffic would be.

[Dave2150]

BT wholesale network cannot handle queued packets so the IP profile gets set to slightly below I think what the natural flow of traffic would be.

Hi Chrysalis, thanks for this info. I'm assuming Sky's network doesn't have such a limitation? I remember my speed test results were very much in line with my sync back then.

I've now resumed uploading to MDWS - interestingly enough my line decided to sync a little higher again today - 36247Kbps - it keeps increasing a tiny bit each day! Unsure if this is just coincidence with the time of day that I power on the modem, or if DLM is seeing my line is error free on the DS side and seeing how far it can push it?

[NewtronStar]

I'm assuming Sky's network doesn't have such a limitation?

They get the same 96% limitations as users on the poor old BT wholesale network 
http://speedof.me/ and see what you get

[Chrysalis]

yeah there is overheads, the profile in itself is no noticeable loss of performance unless it gets stuck, however FTTC ip profiles update instantly on PPP connect, and stuck occurances seem to be extremely rare so I dont really consider BTw's ip profile a problem.  Unlike the old ADSL ip profile's which took 5 days to update.

[Dave2150]

I'm assuming Sky's network doesn't have such a limitation?

They get the same 96% limitations as users on the poor old BT wholesale network 
http://speedof.me/ and see what you get

Thanks for this link, this speed tester seems to represent the speeds I'm seeing when actually downloading content (see attached for imagine, can't direct link it for some reason)

yeah there is overheads, the profile in itself is no noticeable loss of performance unless it gets stuck, however FTTC ip profiles update instantly on PPP connect, and stuck occurances seem to be extremely rare so I dont really consider BTw's ip profile a problem.  Unlike the old ADSL ip profile's which took 5 days to update.

Ah I see, thanks for the information


I see on my MDWS (Dave2150) I seem to have had a sudden DS SNR drop to 3DB around 22:00 yesterday - it doesn't appear to have caused any ES etc. I'm used to my line loosing around 1DB DS SNR each night, then slowly regaining it in the morning etc, but this seems like a much larger drop than I've seen before. I presume it's linked to something electrical turning on, though I can't think of anything in my household that turns on around then. Any thought would be most welcome