Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: 1 [2]

Author Topic: Telnet commands to obtain SATN & LATN data  (Read 7936 times)

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #15 on: June 09, 2014, 11:54:30 PM »

Concerning some of the points above:

The info I reported from --linediag was on my ADSL2+ connection. The modem/router is the Billion 7800DXL. This is a high end model, so it's quite possible that it processes commands more quickly than some others.



Quite possibly the speed of the modem will have an impact, as will the PC's speed & the vastly reduced amount of data produced via an ADSL connection.

Pro-rata, I estimate my setup would produce the linediag data in about 0.22 seconds for an ADSL2+ connection



Quote
The attenuation values reported in the main stats correspond with the LATN (line attenuation) values in --linediag.


Thanks for confirming that.


Line attenuation shouldn't really change much at each resync, apart from a slight increase during warmer weather or if there is indeed a physical change to the cable properties (such as a permanent or intermitent HR issue).


Signal attenuation is a dynamic measure of 'interference' probably such as equipment being switched on/off or even increased crosstalk.

Quite small changes in Signal attenuation (less than 0.5dB) appear to make quite a difference (2 to 3 Mbps) to sync speeds if resyncing when signal attenuation has changed.
That's on my own connection, where I can't achieve anywhere near the 40 Mbps service cap.

Other achieving the their service cap, with further spare attainable rates/SNRM probably wouldn't see any differences from such small changes in signal attenuation.


I can see those changes in my pbParams data, but they aren't reported in LATN & SATN data.

As we now know there is a difference between Line & Signal attenuation reported by some modems on ADSL connections, plotting changes in SATN along with the already plotted LATN data might just be useful.



Quote
My interleave values are the same as b*cat's (32 down, 1 up), but if I tweak the SNRM down by 3 dB the downstream interleave level increases to 64, and sometimes the upstream will become 2. Over the years these values have always been in that region, so I consider them to be 'normal'.


It seems that interleaving depth adjustments are far more granular for VDSL2 connections, possibly down to an adjustment of 1.
It certainly can be adjusted by less than 10, as seen on my connection.

I have no idea what constitutes low medium or high depths for VDSL2, but perhaps the smaller adjustments allow more flexibility when DLM determines whether or not to apply the next (more severe) stage of delay & INP?

Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #16 on: June 10, 2014, 10:08:54 AM »

If you do want to use the --linediag method, you can get both LATN and SATN in a single command:

Code: [Select]
> adsl info --linediag | grep "LATN\|SATN"
LATN(dB):        43.0            23.8
SATN(dB):        46.8            24.6
 >
Logged
  Eric

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #17 on: June 10, 2014, 06:19:01 PM »

Cheers Eric,


grep isn't actually included in the compiler I use, but extracting the data isn't a problem.

It just seems a waste of resources/time to have to obtain thousands of rows of data from the modem/router just to get the LATN & SATN data.

Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #18 on: June 10, 2014, 06:36:37 PM »

I was suggesting that you get the modem to do the job for you. Send the command above to the modem, and all you get back is those two lines. If the modem doesn't support the --linediag option, then you just get a "too many parameters" type of response. I've experimentally implemented this in DSLstats, and it works well, although it does take an extra quarter of a second or so to complete the sampling.

Logged
  Eric

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #19 on: June 11, 2014, 07:54:11 AM »

Thanks Eric,

I have now added the LATN & SATN data to my ongoing logging program (for ADSL connections only).

I started obtaining the additional data last night on an ADSL2 connection that I monitor remotely & it is indeed much, much quicker than on VDSL2 as the linediag data contains far fewer rows.

The xdslcmd info --linediag command still obtains the whole set of data to a temporary memory buffer though.
The LATN & SATN (& ATTNDR) data is then extracted & the allocated memory is then freed again.

Unexpectedly, SATN data doesn't change, but ATTNDR does, despite a significant change in SNRM as per the attached graph.

I have not yet added graphs for LATN & SATN, but I will be doing so as soon as I get chance.

 
Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #20 on: June 11, 2014, 10:01:26 AM »

Quote
Unexpectedly, SATN data doesn't change, but ATTNDR does, despite a significant change in SNRM as per the attached graph.

That is slightly surprising. At the moment I'm testing a different modem which doesn't support the --linediag command, but later I'll put the Billion back and see if my results are similar to yours.

ATTNDR presumably matches the max attainable speed values.
Logged
  Eric

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #21 on: June 11, 2014, 06:30:16 PM »

ATTNDR presumably matches the max attainable speed values.


It does indeed match & it changes dynamically in line with Max rates:-

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Last initialization procedure status:   0
Max:   Upstream rate = 776 Kbps, Downstream rate = 1444 Kbps
Bearer:   0, Upstream rate = 772 Kbps, Downstream rate = 1244 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    1.3       6.4
Attn(dB):    65.0       37.2
Pwr(dBm):    0.0       12.7


      Down      Up
SNRM(dB):    1.3       6.4
LATN(dB):    65.0       37.2
SATN(dB):    71.4       37.5
TxPwr(dBm):    0.0       12.7
ATTNDR(Kbps):   1444      776
Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #22 on: June 11, 2014, 06:39:01 PM »

I've put my Billion 8800NL back, and it behaves in exactly the same way - SATN never seems to change, but ATTNDR tracks the max attainable speeds.
Logged
  Eric

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #23 on: June 11, 2014, 06:51:15 PM »

I suppose that even when SNRM changes, Signal Attenuation remains static (crosstalk will still be present to the same extent).

SATN might only change if say one or more of the crosstalk disturbers switches off/on their modem/router, thus reducing/increasing crosstalk?

In other words, SATN could be partly used as a measure of crosstalk.
For VDSL2 connections, I have seen some users with very little or no difference between Line & Signal attenuation & others with quite a difference (e.g. my connection):-

Code: [Select]
  VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
  Line Attenuation(dB): 8.2 54.9   N/A   N/A   N/A 22.0 67.4   N/A
Signal Attenuation(dB): 8.2 54.3   N/A   N/A   N/A 31.1 67.4   N/A

Although Signal Attenuation does occasionally change dynamically (slightly) on VDSL2 connections between resyncs.
Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #24 on: June 13, 2014, 11:43:01 AM »

I've been pondering this some more, and I realised that I didn't really have a proper understanding of the difference between line and signal attenuation. This article on the Whirlpool site has clarified it a bit: line attenuation is measured by the DSLAM for a fixed range of parameters including the noise frequency distribution; signal attenuation is measured by the modem for the actual parameters of the connection at the time of the measurement.

So, it's quite possible that the modem only measures the signal attenuation at the time of negotiating the connection, which would explain why it doesn't seem to change between resyncs. On my ADSL2 connection, it does change from one resync to the next; with the Billion 8800NL the previous and current values are:

Code: [Select]
Previous: Down 45.9  Up 24.6
Current:  Down 45.1  Up 24.7
Logged
  Eric

Bald_Eagle1

  • Helpful
  • Kitizen
  • *
  • Posts: 2720
Re: Telnet commands to obtain SATN & LATN data
« Reply #25 on: June 13, 2014, 05:33:34 PM »

So, it's quite possible that the modem only measures the signal attenuation at the time of negotiating the connection, which would explain why it doesn't seem to change between resyncs. On my ADSL2 connection, it does change from one resync to the next; with the Billion 8800NL the previous and current values are:

Code: [Select]
Previous: Down 45.9  Up 24.6
Current:  Down 45.1  Up 24.7


I believe Signal attenuation is supposed to be reported dynamically (at least for VDSL2 connections).

I do see 'small' fluctuations between resyncs on my connection (see attached graphs)

Perhaps the ADSL standard doesn't have dynamic Signal attenuation reporting?


« Last Edit: June 13, 2014, 05:35:41 PM by Bald_Eagle1 »
Logged

roseway

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 39471
  • Penguins CAN fly
    • DSLstats
Re: Telnet commands to obtain SATN & LATN data
« Reply #26 on: June 13, 2014, 06:41:57 PM »

On my ADSL2+ connection I've never seen any change in signal attenuation between resyncs, but I don't plot it, so it may have changed without my noticing it.
Logged
  Eric

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 32107
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: Telnet commands to obtain SATN & LATN data
« Reply #27 on: June 13, 2014, 08:00:09 PM »

Ive refrained from commenting because this is something I went over with time and time and time again with konrado and Im now weary to a point you wont believe about making any posts about anything.

AIUI this is what's been on the site for a while What is the difference between Line Attenuation and Signal Attenuation? (although I did change the layout some time last year)

Quote
~ What is the difference between Line Attenuation and Signal Attenuation?

Routers that display two sets of attenuation figures are usually reporting the Signal Attenuation and Line Attenuation.   In these cases it can be taken to mean:-

    Line (or Loop) Attenuation is an average of all the tones available for use in the relevant dsl spectrum - regardless of if the tones are in use or not.
    Loop attenuation is calculated during the transceiver training phase of the sync process and is an estimation of the line attenuation averaged through all the upstream or downstream subcarriers.
    Signal Attenuation is monitored and reported as an ongoing process and can sometimes be affected by ongoing changes in line conditions. Calculation is performed as the difference between the power transmitted at the far end and the power received at the near end.
    Signal attenuation is based an average of the frequency bins actually in use


Read more: http://www.kitz.co.uk/adsl/linestats.htm#Signal_v_Line_Attenuation#ixzz34Xng8Wht



During the time when he was asking questions elsewhere, he got practically the same answer from Phil (yarwell) on TBB about SATN.
Yes LATN is measured by the DSLAM during sync process.   SATN is ongoing and will change.  The bitswap process could affect SATN, as well as SNR (which is what triggers changes to bitswap)

When I had a line fault last year my SATN would change - and quite often -  which is why I asked eric if he could put it into dslstats.
Since the fault has been fixed it seldom, if ever, changes - at least not that Ive noticed.

>>> Perhaps the ADSL standard doesn't have dynamic Signal attenuation reporting

My guess would be its more like something to do with the required diagnostic parameters of G.997.1 which which hopefully standardise the reporting of attenuation, rather than the mix-match that we previously had where router A would report attenuation in an entirely different manner than router B.  Thats not to say that some adsl routers may not already report LATN and SATN separately.

I'd be a bit wary of using SATN to gauge crosstalk, because it can be affected by other factors.   Your LATN & SATN figures intrigue me..  I think I commented a couple of months ago that they were odd (iirc I may have said 'nagged at me'), but why they are like that Ive no idea.

FWIW Ive lost near 20Mb from my max headline speed due to crosstalk (although the Zyxel gave me 3.5Mb back) - yet my attenuation figures havent really changed much over the past year.  Both my LATN & SATN were 36.4 in D3, now its 37.0 for both.   I certainly dont see that wide discrepancy that you do.

------
ETA

>> Quite small changes in Signal attenuation (less than 0.5dB) appear to make quite a difference (2 to 3 Mbps) to sync speeds if resyncing when signal attenuation has changed.

I dont know for certain, but could that be more to do with bit your bitloading.   ie signal atten measuring atten from only tones in use?
To know for sure we'd need to see individual attenuation per tone figures - which arent reported :/




« Last Edit: June 13, 2014, 08:17:44 PM by kitz »
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 32107
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: Telnet commands to obtain SATN & LATN data
« Reply #28 on: June 13, 2014, 08:25:24 PM »

PS

Quote
Loop attenuation is calculated during the transceiver training phase of the sync process and is an estimation of the line attenuation averaged through all the upstream or downstream subcarriers.

I should really clarify on that when it comes to VDSL2 - by adding 'bins in each subcarrier band'.
« Last Edit: June 13, 2014, 08:27:31 PM by kitz »
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

konrado5

  • Reg Member
  • ***
  • Posts: 896
Re: Telnet commands to obtain SATN & LATN data
« Reply #29 on: June 24, 2014, 01:33:45 PM »

I see signal attenuation changes only for upstrem (only after bitswap). For downstream my signal attenuation is always the same as line attenuation. I've seen it also on JDSU, therefore it is normal. I suspect it is caused by fact that router doesn't report upstream power output fluctuations while reports downstrem power output fluctuations.
« Last Edit: June 24, 2014, 01:43:49 PM by konrado5 »
Logged
Pages: 1 [2]