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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Noise, attenuation and CRC figures?



 
 
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  #3  
Old April 23rd 05, 10:18 PM posted to uk.telecom.broadband
Bill
external usenet poster
 
Posts: 74
Default Noise, attenuation and CRC figures?

Martin Underwood wrote:

I'm about 100 metres from my local exchange as the crow flies and the wires
can't be more than twice that distance. My results a

Downstream Upstream
Line Attenuation 30.3 dB 31.0 dB
Noise Margin 6.0 dB 5.5 dB



They seem truly awful for your situation, unless you've quoted in reverse !
I am at 300m and get 8dB att, 40dB margin

Bill

  #4  
Old April 24th 05, 01:11 PM posted to uk.telecom.broadband
stephen
external usenet poster
 
Posts: 50
Default Noise, attenuation and CRC figures?

"Martin Underwood" wrote in message
...
"Grant" wrote in message
...
"Nigel M" wrote in message


Operation Data Upstream Downstream
Noise Margin 31 dB 31 dB
Attenuation 28 dB 25 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 7 0

Are the noise and attenuation figures about right?


Look very good.

From my frequently dodgy long reach Pipex/3Com:

Operation Data Downstream
Noise Margin 9 dB
Attenuation 64 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 47845 331


Yes, very good results.

I'm about 100 metres from my local exchange as the crow flies and the

wires
can't be more than twice that distance. My results a

Downstream Upstream
Line Attenuation 30.3 dB 31.0 dB
Noise Margin 6.0 dB 5.5 dB


Very good attentuation figures but the noise margin is nowhere near as

good
as the OP's.


Agreed. And since at this kind of attenuation you should have much better
noise margin, there may well be a problem on your system.

I had to fix a similar issue for a family member (with higher attenuation,
so margin was around 4 dB) - once we sorted out the house wiring the noise
figures improved by 10 dB......


So far, the speed tests that I have done have varied between 1.2 and 1.9
Mbit/sec (for a 2Mbit/sec service), so it doesn't affect the transfer

rate.
I'm sure the lower speed results are simply due to contention.

--
Regards

Stephen Hope - return address needs fewer xxs


  #5  
Old April 24th 05, 01:40 PM posted to uk.telecom.broadband
Martin Underwood
external usenet poster
 
Posts: 251
Default Noise, attenuation and CRC figures?

"stephen" wrote in message
...
"Martin Underwood" wrote in message

I'm about 100 metres from my local exchange as the crow flies and the

wires
can't be more than twice that distance. My results a

Downstream Upstream
Line Attenuation 30.3 dB 31.0 dB
Noise Margin 6.0 dB 5.5 dB


Very good attentuation figures but the noise margin is nowhere near as

good
as the OP's.


Agreed. And since at this kind of attenuation you should have much better
noise margin, there may well be a problem on your system.

I had to fix a similar issue for a family member (with higher attenuation,
so margin was around 4 dB) - once we sorted out the house wiring the noise
figures improved by 10 dB......


Well the underground wiring to the house will have been installed about four
years ago and probably takes a direct line back to the exchange since all
the land was derelict before my development was built so they didn't need to
go via the road. Even if they did go via the main road, the length is
probably not more than 200-300 metres.

The socket where the router is plugged in was installed by BT: from the
master socket, it goes through the outside wall, up the outside and in
through the bedroom wall to the socket. It's good thick 2-core BT wire -
looks like the sort that they use between the pole and your house. In
parallel with this, also leading off the master socket, is wiring installed
by the builder which leads to further sockets in the lounge and in another
bedroom. It would be interesting (but illegal!) to disconnect the house
wiring and BT-installed wiring to see if it made any difference.

When I first got the router, before my broadband was enabled, I tried it at
my parents' house and got very similar figures for much older wiring and
much further distance - probably about 1.5 km. And long lengths of
non-BT-installed wiring from the master socket, with several junctions and
splitters.

I've just tried plugging the router into my master socket to see if the
figures
changed at all, but it made an improvement (increase) of only about 0.5 dB
to the
upstream noise and an improvement (decrease) in downstream attenuation of 1
dB; interestingly the downstream noise figure stayed the same despite
slightly less attenuation.

But since I'm getting good transfer rates (apart from connection) then the
noise figure is a bit academic really!


  #7  
Old April 26th 05, 11:04 AM posted to uk.telecom.broadband
mr_flibble
external usenet poster
 
Posts: 1
Default Noise, attenuation and CRC figures?


Dave Wrote:
"Grant" wrote in message
...-
"Nigel M"
wrote in message
-

Operation Data Upstream Downstream
Noise Margin 31 dB 31 dB
Attenuation 28 dB 25 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 7 0

Are the noise and attenuation figures about right?-

Look very good.

From my frequently dodgy long reach Pipex/3Com:
-
Operation Data Downstream
Noise Margin 9 dB
Attenuation 64 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 47845 331--

Do you get frequent disconnects with those stats? I'm 63dB att. 11d
margin
and the router disconnects and reconnects about half a dozen times
day
over the weekend. Never seems to do it during the night or during a
weekday.
-

-


I too have a poor line, these are my stats from my router.

ADSL Line State: Up
ADSL Startup Attempts: 0
ADSL Modulation: Unknown
Datapump Version: 3.38.2
Downstream Upstream
---------- ----------
SNR Margin: 8.81 20.00 dB
Line Attenuation: 63.98 31.50 dB
Output Power: 15.83 12.33 dB
Errored Seconds: 0 0
Loss of Signal: 0 0
Loss of Frame: 0 0
CRC Errors: 8388 696
Data Rate: 1152 288


I know it looks like there are a lot of errors but the router has bee
up for more than 5 days with no disconnects. So something must b
working ok.

Just wish I lived a little closer to the exchange, or had a better lin
for faster services. I am 3.74km from the exchange as the crow flies
according to samknows.

I wonder if there is any aluminium in my line? How would I find out

--
mr_flibble
  #8  
Old April 26th 05, 05:54 PM posted to uk.telecom.broadband
kraftee
external usenet poster
 
Posts: 1,069
Default Noise, attenuation and CRC figures?


"mr_flibble" wrote in message
...

Dave Wrote:
"Grant" wrote in message
...-
"Nigel M"
wrote in message
-

Operation Data Upstream Downstream
Noise Margin 31 dB 31 dB
Attenuation 28 dB 25 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 7 0

Are the noise and attenuation figures about right?-

Look very good.

From my frequently dodgy long reach Pipex/3Com:
-
Operation Data Downstream
Noise Margin 9 dB
Attenuation 64 dB

Defect Indication
Indicator Name Near End Indicator Far End Indicator
Fast Path CRC Error 47845 331--

Do you get frequent disconnects with those stats? I'm 63dB att. 11dB
margin
and the router disconnects and reconnects about half a dozen times a
day
over the weekend. Never seems to do it during the night or during a
weekday.
-

-


I too have a poor line, these are my stats from my router.

ADSL Line State: Up
ADSL Startup Attempts: 0
ADSL Modulation: Unknown
Datapump Version: 3.38.2
Downstream Upstream
---------- ----------
SNR Margin: 8.81 20.00 dB
Line Attenuation: 63.98 31.50 dB
Output Power: 15.83 12.33 dB
Errored Seconds: 0 0
Loss of Signal: 0 0
Loss of Frame: 0 0
CRC Errors: 8388 696
Data Rate: 1152 288


I know it looks like there are a lot of errors but the router has been
up for more than 5 days with no disconnects. So something must be
working ok.

Just wish I lived a little closer to the exchange, or had a better line
for faster services. I am 3.74km from the exchange as the crow flies,
according to samknows.

I wonder if there is any aluminium in my line? How would I find out?


You can't, even the Bt cable records haven't been kept up to date when & if
the cables have been changed...

The only clue you may have is if you talk to one of the older u/g engineers
who may have local knowledge, but they are few & very far between now, hell
I've only been on the tools for 15 years now & I'm one of the longest
serving engineers in my patch & I'm still learning...


 




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