Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[konrado5]

Someone in Poland have similar tone gap as I. Which Hlog is better? First is my, second is its.

Best regards
konrado5

[burakkucat]

Of the two Hlog graphs, the second one is the "better" one. Notice that the attenuation smoothly increases with the frequency, without any "roll" that is present in the first graph.

Before you ask the question I will say that I have no idea why two (apparently) similar circuits should show different behaviour in their Hlog graphs. Likewise, I have no idea what is the cause of the "roll" that is present in your graph. 

[konrado5]

Likewise, I have no idea what is the cause of the "roll" that is present in your graph.

My home installation maybe? I have above 5 meters cable from socket to router.

[burakkucat]

My home installation maybe? I have above 5 meters cable from socket to router.

I have no idea. 

But, surely, you could perform an experiment to see if that cable is responsible? Just move the modem/router to the socket and use a mains supply extension lead to temporarily provide the power. Allow the modem - DSLAM to synchronise and then harvest the data. Plot the Hlog graph and view the result.

[konrado5]

I'll do it but not at this moment because I have 16248 kbps with 3 dB from 2 months. I don't want to disconnect. This man have similar tones gap. He have 415-474 tones not used.
http://obrazki.elektroda.pl/1949157100_1395010806.jpg
However his QLN looks very better. First is my QLN, second is his QLN.
Moreover, his router shows SNR on unused tones, my router reports 0 dB on unused tones. Is his gap have the same cause as my gap? He lives in other town.

I see also similar DSLAM. I have:

Code: [Select]

ChipSet Vendor Id: BDCM:0x   0
ChipSet VersionNumber: v10.06.47     
ChipSet SerialNumber:
0
His DSLAM is:

Code: [Select]

ChipSet Vendor Id: BDCM:0x6093
ChipSet VersionNumber: 0x6093
ChipSet SerialNumber:
This gap is caused by strange DSLAM maybe?

Best regards
konrado5

[burakkucat]

b*cat nods his head after viewing the bit-loading per tone. It does look rather similar to your own. 

Again, I would agree that his QLN graph does, overall, look "better" than your own . . . however both of them are better than mine!

Let us look a little closer at the two QLN plots. Notice that the overall level of the first graph is between -120 & -110 dBm, whereas the overall level of the second graph is between -110 & -100 dBm. Now remember that the more negative the overall level (that is the more quieter) the better the graph. So although, by eye, the shape of the second graph looks "better" I would say that the first graph is preferable, as it has a lower average "noise floor".

Moreover, his router shows SNR on unused tones, my router reports 0 dB on unused tones. Is his gap have the same cause as my gap? He lives in other town.

There is really nothing I can say. I just do not know. 

Finally, with regards to the two DSLAMs -- all we can say, with certainty, is that they both use Broadcom chipsets. Nothing else is obvious. 

I attach, below, my current QLN graph. Notice that I have two distinct "noise floors" -- between -115 & -120 dBm for US and between -130 & -140 dBm for DS. Although the overall "noise floor" is quieter than the two graphs that you have shown, I have severe RFI at various frequencies.

[konrado5]

burakkucat: Thank you very much for reply. I remember earlier on this forum it has been considered that amteur radio causes this gap. Do you still believe radio can cause this gap or rather fault router or fault DSLAM? Moreover, this man have also slightly lower upstream since he have gap on download. I also have lower upstream since I have 3 mbps lower synchronization but I don't know if I had gap at that time.

Best regards
konrado5

[burakkucat]

Well . . . the frequencies involved do correspond quite closely to the amateur radio "top band" (the 160 metre band). In the UK the frequency range is 1810 - 2000 kHz.

Perhaps CPs / ISPs in Poland deliberately avoid using that band of frequencies? 

[konrado5]

Perhaps CPs / ISPs in Poland deliberately avoid using that band of frequencies? 

However, there are small differences between distinct synchronizations eg. sometimes tone 410 is used, sometimes is not used. Moreover, there is very low SNR nearly the unused tones.
 

Code: [Select]

404 20.6250
   405 19.3125
   406 17.7500
   407 16.6250
   408 14.9375
   409 13.5625
   410 12.6875
   411 0.0000
   412 0.0000Maybe there is power cut back on some frequiencies?

Best regards
konrado5

[burakkucat]

Yes, that could be a possibility. However I do not have any knowledge of how Polish CPs / ISPs configure their xDSL services.

You should really submit these detailed questions to your CP / ISP. I guess the problem is making contact with someone who has sufficient knowledge and seniority . . . not the "front line" support desk.

[kitz]

Perhaps CPs / ISPs in Poland deliberately avoid using that band of frequencies? 

However, there are small differences between distinct synchronizations eg. sometimes tone 410 is used, sometimes is not used. Moreover, there is very low SNR nearly the unused tones.
 

Code: [Select]

404 20.6250
   405 19.3125
   406 17.7500
   407 16.6250
   408 14.9375
   409 13.5625
   410 12.6875
   411 0.0000
   412 0.0000Maybe there is power cut back on some frequiencies?

Best regards
konrado5

Due to the fact that you say sometimes a very low snr my gut instinct would say its more likely a local interference...  Or just plain mush that happens for no apparent reason on many many lines and is considered within the realms of adsl normality.   
It's seldom you see a line that is completely perfect.  Even very short lines can show troublesome tones .   For a line to be perfect it would have to be right next to the dslam, have no other lines on the dslam and no source of any local interferance.

When it comes to ISP based (and I'm sure I've mentioned this before) the totally block the tone from use.  A typical example of this would be similar to what BE/O2 MSANs in the uk used to do.  This takes the tones completely out of use, they did this susposedly because some areas in London where affected by radio wave type interferance. 

Another ISP related possibility is test tones, which can have a couple of bits loaded. These are normally within a set range.   As bcat says your ISP is the best person to ask about this.

[konrado5]

I've tried to contact my ISP, however they persuade me that my SNR on tones graph is typical for ADSL2+ long lines. They say I shoud compare my graph with other graphs (they say then I will see it is typical). However I've seen many graphs in Poland. It is not typical.

Another ISP related possibility is test tones, which can have a couple of bits loaded.

My router reports that these tones have 0 bits loaded.

Best regards
konrado5

[konrado5]

Sometimes my router disables starting tone for upstream if on the other tones there are very good conditions at synchronization establishment time. During 65 days I've had 16248/1245 kbps with SNR margin for download 3-4 dB. I've had following bit-loading for upstream (7th tone not used):

Code: [Select]

Tone number      Bit Allocation
   0 0
   1 0
   2 0
   3 0
   4 0
   5 0
   6 0
   7 0
   8 10
   9 12
   10 13
   11 14
   12 14
   13 15
   14 15
   15 15
   16 15
   17 15
   18 15
   19 15
   20 15
   21 15
   22 15
   23 15
   24 14
   25 14
   26 14
   27 13
   28 13
   29 12
   30 11
   31 11
Now I have 1221 kbps with 7th tone used:

Code: [Select]

Tone number      Bit Allocation
   0 0
   1 0
   2 0
   3 0
   4 0
   5 0
   6 0
   7 8
   8 10
   9 11
   10 12
   11 14
   12 14
   13 14
   14 14
   15 14
   16 14
   17 14
   18 14
   19 15
   20 15
   21 15
   22 15
   23 14
   24 14
   25 14
   26 13
   27 13
   28 12
   29 12
   30 11
   31 9
I've written about it earlier:
http://forum.kitz.co.uk/index.php?topic=13446.0
Kitz said me that my ISP changed PSD masks. However kitz was wrong. I've lost synchronization and I have 7th tone used again despire lower synchronization rate.

Before I've got 16248 kbps/1245 kbps I've had also 1221 kbps upstream with following bit-allocation:

Code: [Select]

Tone number      Bit Allocation
   0 0
   1 0
   2 0
   3 0
   4 0
   5 0
   6 0
   7 7
   8 9
   9 12
   10 12
   11 13
   12 14
   13 14
   14 14
   15 14
   16 14
   17 14
   18 15
   19 15
   20 15
   21 15
   22 15
   23 14
   24 14
   25 14
   26 14
   27 13
   28 13
   29 12
   30 10
   31 9
Perhaps January Hlog  and QLN (7th tone not used) and March Hlog and QLN(7th tone used) will be helpful.

Best regards
konrado5

[kitz]

Kitz said me that my ISP changed PSD masks. However kitz was wrong.

iirc I said perhaps your ISP has different tones in use since the change of dslam and was offering it as a possible suggestion as to why different tones are in use. 
TBH I feel like Im going round in circles sometimes because Ive suggested all sorts of things and Im really not sure what info you want or for us to say.

[konrado5]

I said perhaps your ISP has different tones in use since the change of dslam and was offering it as a possible suggestion as to why different tones are in use. 

Perhaps I've said it obscurely. I thought about: on the same DSLAM I've had not used 7th tone on upstream only when I've had 1245 kbps upstream. When I have 1221 kbps I have always used 7th tone with about 7 bits. Is it possible sometimes starting tone is disabled if remaining tones are very loaded? You didn't agree with me in reply #9
http://forum.kitz.co.uk/index.php?topic=13446.0
However as I've got new synchronization I have again 7th tone used.

I suspect on old DSLAM i've had on some connections 10 tones with stable SNR disabled.

Best regards
konrado5