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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.

Question about downstream power output



 
 
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  #1  
Old November 1st 08, 04:41 PM posted to uk.telecom.broadband
Stuart Rogers
external usenet poster
 
Posts: 13
Default Question about downstream power output

I have recently aquired a D-Link DSL-2740B router which although is working
OK there are a couple of issues I'm trying to sort out. The main one right
now is that it always reports the downtream power output as 0.0dBm both on
its stats web page and on the output of the adsl command when I telnet into
the router. The upstream power is usually shown as about 12.9dBm.

Now my question is on an ADSL2+ connection should I see a valid non-zero
value in this field? Do others see this as a non-zero value on this router?

If it should show a non-zero value does this indicate a problem with this
router?

Thanks
  #2  
Old November 1st 08, 09:11 PM posted to uk.telecom.broadband
alexd
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Posts: 1,765
Default Question about downstream power output

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The main
one right now is that it always reports the downtream power output as
0.0dBm


If it should show a non-zero value does this indicate a problem with this
router?


I believe that the downstream power output isn't calculated by your router,
the value is communicated to the router by the kit in the exchange. So if
there is a minor incompatibility between the DSLAM and your router, you'll
see nothing or nonsense in that field. Alternatively, it may be a bug in
the router's firmware.

--
http://ale.cx/ (AIM:troffasky) )
21:09:29 up 17 days, 2:00, 2 users, load average: 0.05, 0.06, 0.01
They call me titless because I have no tits

  #3  
Old November 2nd 08, 11:07 PM posted to uk.telecom.broadband
Stuart Rogers
external usenet poster
 
Posts: 13
Default Question about downstream power output

alexd wrote in :

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm


If it should show a non-zero value does this indicate a problem with
this router?


I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM and
your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.


Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both may be
not communicating with the DSLAM properly over this. I suppose it could be
that the DSLAM may not be sending the data either.
  #4  
Old November 3rd 08, 11:14 AM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 1,000
Default Question about downstream power output

Stuart Rogers wrote:
alexd wrote in :

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm
If it should show a non-zero value does this indicate a problem with
this router?

I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM and
your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.


Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both may be
not communicating with the DSLAM properly over this. I suppose it could be
that the DSLAM may not be sending the data either.


Well perhaps your exchange IS transmitting at 0dbM.


Its a perfectly reasonable power level.
  #5  
Old November 3rd 08, 08:39 PM posted to uk.telecom.broadband
Stuart Rogers
external usenet poster
 
Posts: 13
Default Question about downstream power output

The Natural Philosopher wrote in
:

Stuart Rogers wrote:
alexd wrote in
:

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm
If it should show a non-zero value does this indicate a problem
with this router?
I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM
and your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.


Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both
may be not communicating with the DSLAM properly over this. I suppose
it could be that the DSLAM may not be sending the data either.


Well perhaps your exchange IS transmitting at 0dbM.


Its a perfectly reasonable power level.


Yes it could be but I'm on a 3km line and so I would have thought it
would need some power!
  #6  
Old November 3rd 08, 09:23 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 389
Default Question about downstream power output


"Stuart Rogers" wrote in message
. 1.4...
The Natural Philosopher wrote in
:

Stuart Rogers wrote:
alexd wrote in
:

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm
If it should show a non-zero value does this indicate a problem
with this router?
I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM
and your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.


Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both
may be not communicating with the DSLAM properly over this. I suppose
it could be that the DSLAM may not be sending the data either.


Well perhaps your exchange IS transmitting at 0dbM.


Its a perfectly reasonable power level.


Yes it could be but I'm on a 3km line and so I would have thought it
would need some power!


Googled for dBm and found:


  #7  
Old November 3rd 08, 09:32 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 389
Default Question about downstream power output


"Stuart Rogers" wrote in message
. 1.4...
The Natural Philosopher wrote in
:

Stuart Rogers wrote:
alexd wrote in
:

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm
If it should show a non-zero value does this indicate a problem
with this router?
I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM
and your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.


Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both
may be not communicating with the DSLAM properly over this. I suppose
it could be that the DSLAM may not be sending the data either.


Well perhaps your exchange IS transmitting at 0dbM.


Its a perfectly reasonable power level.


Yes it could be but I'm on a 3km line and so I would have thought it
would need some power!


I googled and found :
http://www.jneuhaus.com/volts_to_dBm.html

which shows the line:

Volts-rms 0.775 Vrms
Volts-peak-to-peak 2.191 Vpp
dBm(Z=50ohm) 10.8 dBm
dBm(Z=75ohm) 9.0 dBm
dBmv(Z=75ohm) 57.8 dBmv
dBm(Z=600ohm) 0.0 dBm

So 0.0 dBm is 0.775 Vrms across 600 ohm i.e. 1mW - or a perfectly adequate
level of power to get down 3km of phone line.

A mate at BBC broadcasting house used to joke that their output was 1mW into
600 ohm for each programme channel - an expensive way to sell electricity!!!

--
Graham J





  #8  
Old November 3rd 08, 10:39 PM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 1,000
Default Question about downstream power output

Stuart Rogers wrote:
The Natural Philosopher wrote in
:

Stuart Rogers wrote:
alexd wrote in
:

Stuart Rogers wrote:

I have recently aquired a D-Link DSL-2740B router which although is
working OK there are a couple of issues I'm trying to sort out. The
main one right now is that it always reports the downtream power
output as 0.0dBm
If it should show a non-zero value does this indicate a problem
with this router?
I believe that the downstream power output isn't calculated by your
router, the value is communicated to the router by the kit in the
exchange. So if there is a minor incompatibility between the DSLAM
and your router, you'll see nothing or nonsense in that field.
Alternatively, it may be a bug in the router's firmware.

Well I've now tested another router of a different make on the same
connection and it does not display this value either. I guess both
may be not communicating with the DSLAM properly over this. I suppose
it could be that the DSLAM may not be sending the data either.

Well perhaps your exchange IS transmitting at 0dbM.


Its a perfectly reasonable power level.


Yes it could be but I'm on a 3km line and so I would have thought it
would need some power!


No, the power level at the exchange is pretty constant I think. That's
why the long line loses bandwidth..increase the power and it will start
buggering other peoples DSL..

 




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