What is Spectrum Profile?

Forums › Spark New Zealand (including Skinny and BigPipe) › What is Spectrum Profile?

loafer

6 posts

Wannabe Geek

#69506 9-Oct-2010 15:02

I work at an ISP associated with TCNZ. I have often come across a term, Spectrum Profile, but no one seems to know exactly what it is. The Wholesale manual does not define the term. Anyone has any idea? The profile is supposed to be changed by Port Reset if it not standard.

cyril7

9058 posts

Uber Geek

ID Verified

Trusted

Subscriber

#389887 9-Oct-2010 15:22

Hi, DSL operates by using a whole spectrum of carriers or bins, depending on the noise (and in particular the spectral distribution of that noise) and line length exactly what carriers are used can be manipulated to provide a more stable connection, I presume this is what they are calling spectrum profile.

Cyril

cbrpilot

955 posts

Ultimate Geek

Trusted

Spark NZ

#390011 9-Oct-2010 22:44

I'm not expert on this, so I can't provide a more full explanation other than saying that it's part of the ISAM port config. Amongst other things it specifies which variant of xDSL to sync at and what power profile to use. As Cyril says, it also includes any per bin config (which may be things like "back off on these frequencies" - currently not used for ADSL).

A port reset will not change this config. A port "refresh" will align it back to what the provisioning systems thinks it should be. I.e. if someone had manually gone in and changed it via the element manager without telling the provisioning system, a port refresh will bring them back into alignment (same with the service profile). That's probably more of a side-effect rather than a feature though ....

Hope this helps.

My views are my own, and may not necessarily represent those of my employer.

loafer

6 posts

Wannabe Geek

#390028 10-Oct-2010 00:06

Thanks for the tip. I think I first have to understand what carrier is. My colleague told me that it is actually PPP itself, but I am not convinced. How could 'carrier' be best described in this context? I know users with frequent disconnection/no PPP issues are characterised by lost-carrier, but I am vague on its technical sense.

richms

28187 posts

Uber Geek

Trusted

Lifetime subscriber

#390032 10-Oct-2010 00:19

carrier is a hold over from the analog modem days when you had a signal that you modulated to carry data, that signal is the carrier.

Lost carrier meant that the connection to the other end was distrupted but disconnection or noise, and in the case of a dialup modem that you would have to redial to get it back again.

there are 100s of carriers on dsl, loss of some doesnt make it disconnect, so to call it a carrier lost is a bit wrong, it means that the 2 ends have given up communicating because the line has become bad, or in more common cases the end user has a crap router that has crashed or been turned off.

Richard rich.ms

raytaylor

4014 posts

Uber Geek

Trusted

#390042 10-Oct-2010 04:07

I see it like this

Imagine a FM radio band 88-108mhz
At various points you will have stations.
If you want to send heaps of data, you have to send it between the stations, or other users of the band.

So a spectrum profile would start off by saying "use the whole band"
But as errors occur, it discovers that there are other users at various points in the band and doesnt transmit on these frequencies so that the data can be sent more reliably.

When you have a cable go from the exchange or dslam to a cabinet, it can go through a cable with many other phone lines. The wires are twisted in pairs so there isnt signal interference between the lines inside the cable, but some signals do leak into other pairs or lines and it causes interference.
So the profile changes on the line so that it can get data through correctly without errors by avoiding the frequencies that have interference from the other lines in the cable.

This results in a slower connection speed. By resetting the port, the speed will then increase because the full range of frequencies becomes avaliable again but could be unreliable, untill it adapts to work around interference from other lines.

Ray Taylor

There is no place like localhost

Spreadsheet for Comparing Electricity Plans Here

raytaylor

4014 posts

Uber Geek

Trusted

#390043 10-Oct-2010 04:16

Above is a spectrum analysis i have done using a radio just now.
We can see that if i wanted to send data, i would use frequency 1,2,3,11-16
I would avoid bins 5-9, 17 and 18 because there is interference from another radio / telephone line - so if i sent something in bin 7, the reciever wouldnt be able to understand what I said.

All the bins that are avaliable are used all at the same time so data travels faster by going in parallel on different frequencies or bins.

So my spectrum profile would adjust over time so it learns what to avoid so that the link is most reliable and less likley to turn to errors.

Ray Taylor

There is no place like localhost

Spreadsheet for Comparing Electricity Plans Here

loafer

6 posts

Wannabe Geek

#390169 10-Oct-2010 15:04

Thanks for more replies. I see spectral profile and and port referesh relate to signal processing. Might have to start mugging up on it..