7800n config adjustment help

Harvey_NFFC
Posts: 7
Joined: Sun Jan 26, 2014 5:09 pm

7800n config adjustment help

Post by Harvey_NFFC » Sun Jan 26, 2014 5:19 pm

My line is ADSL
These are my stats:
Operational Mode G.DMT
Upstream 448
Downstream 1088
SNR Margin(Upstream) 20.0
SNR Margin(Downstream) 9.6
Line Attenuation(Upstream) 31.5
Line Attenuation(Downstream) 63.5

I have:
ADSL Mode :Annex L (unticked) Annex M (ticked)
Modulator: ADSL2 ADSL2+ G.Lite T1.413 G.Dmt (ticked)
Capability: SRA (unticked)
PhyR : Upstream Downstream (both unticked)

My line is 4.5/5km. Could anyone help me with the above. I haven't played with snr as I don't know what I'm doing. My line is fairly stable and is usually a stable 1.2 meg but dropped today slightly.

Tomken
Posts: 467
Joined: Tue Jul 26, 2011 10:31 am
Location: Co Durham

Re: 7800n config adjustment help

Post by Tomken » Mon Jan 27, 2014 9:32 am

A guide to adjusting the Target SNR Margin can be found in http://www.spaldwick.com/broadband/billion-7800n

The Table gives basic adjustments but you can +/- 5 or 10dB to those for fine adjustment and initially using the value of 75 will reduce the Margin by 1.5dB.

As you are almost 4.6km (63.5/13.81) from the exchange then your speeds are never going to be great, you may get some improvement from the tweaking although you should never sacrifice stability for speed.

If you are with BT then you may get away with a slight tweak as BT's DLM tends to kick in and will revert you to your original Profile of 9.6.

Your speed dropping could be due to a line problem so it may be best to contact your ISP before you start tweaking.

Harvey_NFFC
Posts: 7
Joined: Sun Jan 26, 2014 5:09 pm

Re: 7800n config adjustment help

Post by Harvey_NFFC » Mon Jan 27, 2014 8:52 pm

Since I let the line settle it has changed to:
Operational Mode G.DMT
Upstream 448
Downstream 1696
SNR Margin(Upstream) 20.0
SNR Margin(Downstream) 8.9
Line Attenuation(Upstream) 31.5
Line Attenuation(Downstream) 63.5

Tomken
Posts: 467
Joined: Tue Jul 26, 2011 10:31 am
Location: Co Durham

Re: 7800n config adjustment help

Post by Tomken » Mon Jan 27, 2014 10:07 pm

Not sure if you will be able to squeeze a little more out of that as you will see if you put 64 into http://www.kitz.co.uk/adsl/max_speed_calc.php (it doesn't do .5s) and those speeds are an estimate based on a 6dB profile.

If you have a fluctuating SNR Margin then that can affect your speeds just as you can experience a drop at peak periods, so taking speed tests throughout the day may ID if the drops are due to the peak periods or if due to an intermittent line fault.

inSSIDer can show if you are on the best channel to use for your area which may also help http://www.techspot.com/downloads/5936-inssider.html

Harvey_NFFC
Posts: 7
Joined: Sun Jan 26, 2014 5:09 pm

Re: 7800n config adjustment help

Post by Harvey_NFFC » Thu Jun 11, 2015 5:11 pm

Hi,

My sync speed now max's at about 2000, but my IP profile is only 1200. Should I be getiing more?

Thanks

billion_fan
Posts: 5272
Joined: Tue Jul 19, 2011 4:30 pm

Re: 7800n config adjustment help

Post by billion_fan » Fri Jun 12, 2015 9:37 am

Harvey_NFFC wrote:Hi,

My sync speed now max's at about 2000, but my IP profile is only 1200. Should I be getiing more?

Thanks
Whats your ADSL stats like?

Harvey_NFFC
Posts: 7
Joined: Sun Jan 26, 2014 5:09 pm

Re: 7800n config adjustment help

Post by Harvey_NFFC » Sat Jun 13, 2015 11:34 am

Here you are:

DSP Firmware Version A2pB025f.d22k
DMT Status No Defect
Operational Mode G.DMT
Upstream 448
Downstream 1888
SNR Margin(Upstream) 19.0
SNR Margin(Downstream) 6.4
Line Attenuation(Upstream) 31.5
Line Attenuation(Downstream) 63.5

billion_fan
Posts: 5272
Joined: Tue Jul 19, 2011 4:30 pm

Re: 7800n config adjustment help

Post by billion_fan » Mon Jun 15, 2015 9:28 am

Harvey_NFFC wrote:Here you are:

DSP Firmware Version A2pB025f.d22k
DMT Status No Defect
Operational Mode G.DMT
Upstream 448
Downstream 1888
SNR Margin(Upstream) 19.0
SNR Margin(Downstream) 6.4
Line Attenuation(Upstream) 31.5
Line Attenuation(Downstream) 63.5
Looking at the SNR downstream value this is lowest setting BT recommend (if you are confident you always try to tweak the SNR lower, but this might cause your line to drop out, you have find the best SNR settings for speed and stability)

Harvey_NFFC
Posts: 7
Joined: Sun Jan 26, 2014 5:09 pm

Re: 7800n config adjustment help

Post by Harvey_NFFC » Mon Jun 15, 2015 11:09 pm

Hi, changing my SNR improves my sync speed but my IP Profile (BRAS) doesn't seem to change. Do I have to ask BT to change this?

billion_fan
Posts: 5272
Joined: Tue Jul 19, 2011 4:30 pm

Re: 7800n config adjustment help

Post by billion_fan » Tue Jun 16, 2015 10:44 am

Harvey_NFFC wrote:Hi, changing my SNR improves my sync speed but my IP Profile (BRAS) doesn't seem to change. Do I have to ask BT to change this?
You can ask BT, but not sure if they will be able to do so, as you far away from the exchange

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