DMT Bits Per Bin ?

Unanswered Question
Mar 26th, 2010

Hi All

I am just wondering if someone knows how to interpret the DMT Bits  Per Bin
we got in a sh dsl int atm0:

DMT Bits Per Bin
000: 0 0 0 0 0 0 0 0 2 3 3 4 5 5 6 6
010: 6 6 6  6 6 5 5 5 5 4 4 3 3 3 3 0
020: 0 0 0 0 0 0 0 0 0 0 0 B B B B B
030:  B B B B B B B B A B B A B A A A
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050:  0 0 0 0 A 0 2 A A 0 A A A 0 0 0
060: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
070:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
080: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
090:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0A0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0B0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0C0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0D0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0E0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0F0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I read first 6 bits where for Voice, the bits until the 31st bits  where for upstream and others where for downstream. Now I am wondering  what means the code
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050: 0 0  0 0 A 0 2 A A 0 A A A 0 0 0

What means the zero value, is that showing bad line quality? Is someoneknows how to interpret this code?

Thanks in advance for your help

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Giuseppe Larosa Fri, 03/26/2010 - 03:57

Hello Melanie,

DMT uses multiple tones at different frequencies the bits per tone means if a specific tone is used or not

the tones are spaced every 4 Khz

in your case those specific lines say that some tones are not used. = 0 bits of modulation per tone

The reasons are: a safe guard is left between upstream and downstream because they travel in different directions so some tones are not used

in this range should also be included the pilot tones that are used to negotiate speed and line rate and to report other diagnostic data

this is an example taken from an ADSL1

DMT Bits Per Bin
000: 0 0 0 0 0 0 0 5 6 7 8 9 9 A A A
010: A A A A A A A 9 9 9 8 8 7 6 0 0
020: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
030: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
040: 0 0 0 0 0 4 4 4 5 5 5 5 5 2 5 5

Hope to help

Giuseppe

melaniemaillet Fri, 03/26/2010 - 06:41

Hi Giuseppe,

Thanks for your help.

Got a another question if the tone is not used, will it affect the downstream quality of the line? As in a tone we can have 0 to 16bits, 0 is bad and 16 is showing good quality?

Ta

Mel

Giuseppe Larosa Fri, 03/26/2010 - 07:13

Hello Melanie,

I agree for those tones that are not intentionally not used

a 0 should be unusable for example for the presence of high interference

note that all this is dynamic: signal to noise ratios are measured for each tone over time intervals, and the modems exchange this information on some special purposes tones used for this OAM and for basic negotiation.

Hope to help

Giuseppe

federico_tv Thu, 01/23/2014 - 00:48

Quite old post...

So I understood the higher is the tone number the higher is that bin capability, so in bandwidth terms, the higher is the sum of all bins in upstream or downstream section, the higher is the bandwidth , isn't it ??

So a pattern rich of  2, 3, 4 values is symptom of bad quality line 

Am I rigth ???

Thanks

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