India Broadband Forum

hexwiz · 08-05-09, 04:48 AM

Quote:

Originally Posted by power_downloader

I have Home 500 C plan. I cannot stay connected for more than 20 min.Suddenly while surfing my speed becomes 0 kB/s for no reason .When I look at my router I see the yellow DSL light blinking which means that its reconnecting(I'm using pppoe mode).The green internet light always blinks.I have read somewhere it means that my connection is out of sync. While surfing this site after every 10-20 min I get a message to log in again which may be because my IP changes after reconnection.Is my SNR too low ?

What are super frame errors ? Are they causing problem?

router:Siemens sl2_141
plan:500C
OS:Windows XP pro

Super frame errors are also known as crc6 errors which means the data packet is corrupted enroute. This could mean a lot many things and going by the stats, the low SNR and high attenuation certainly signify line issues which may be inside the premises or out. You could start with the cables and connections and making sure they are plugged in proper. Make sure the adsl filter is not faulty and that the modem is plugged into the correct adsl port on the filter and not the phone port. If that doesn't resolve the problem it certainly is your provider's call. And on the modem GUI if it gives you an option which says something akin to "Connect on demand" and if it has a check box - leave that UNchecked. EMI can also cause such but I doubt that's what's happening here. But nevertheless you could make sure there is no electronic device too close to the dsl modem or cables as they could cause interference. This would include equipments like speakers, tv tubes, power amplifiers, power supplies, radio, microwaves, cordless phones etc

hexwiz · 08-15-09, 10:04 PM

My last post in this thread was deleted. I'd appreciate if someone could let me in as to why. Thanks

mickey · 08-15-09, 10:05 PM

^^ one cant know the reasons without asking the mods directly.. they always help..

just4kix · 08-16-09, 12:27 PM

Quote:

Originally Posted by hexwiz

My last post in this thread was deleted. I'd appreciate if someone could let me in as to why. Thanks

None of your posts in this thread has been deleted. I checked.

Perhaps you posted somewhere else.

Luke Skywalker · 08-17-09, 10:54 AM

Rated this thread but kix .Please change definition from signal to noise ratio to power ratio between signal to noise as I said earlier. SNR long form is Signal to noise but it is not definition. It is 10 times log(base 10) of ratio of signal power to noise power.

PS: 1. I remember this as I have just studied it in March for my communication exam.
2.Dunno whether I gave rep or not don't want to give again for same. Tell me if I didn't , I will give to it.

just4kix · 08-17-09, 01:28 PM

Changing to Power Ratio will confuse a lot of people as everywhere it mentioned as SNR margin.

just4kix · 08-17-09, 01:28 PM

Changing to Power Ratio will confuse a lot of people as everywhere it mentioned as SNR margin.

Xenon · 08-31-09, 02:12 PM

Nice ! From what your comparision stats say .. my BSNL connection is outstanding

(Probably due to the local exchange being like 400 meters away

and new telephone line)

(Downstream / Upstream)
SNR Margin (dB): 34.0 |7.5
Attenuation (dB): 18.0 |6.1

Output Power (dBm): 8.8 |1.5

Attainable Rate (Kbps): 13720|1028
Rate (Kbps):2048 |928

I am a bit confused about the Rate... it say 2048 or 2 Mbps and my plan is 512 kbps =\
which Rate does that number signify =\ ? I suppose attainable rate is the max supported speed by the router.

just4kix · 08-31-09, 08:49 PM

^ Attainable rate is the maximum achievable by the ADSL connection. Modem can achieve much more.

You actual speed is better ascertained by a speedtest. Do not depend upon the modem results.

Xenon · 08-31-09, 09:28 PM

Oh, speed test was at speedtest.net was around .9 mbps - .4 mbps (download) and .3-.5 upload. I am veeery happy with the speeds I am getting, although I am surprised by how the dl speed goes upto 80Kbps (max till now) on torrents at times. Even when I am sharing it with another PC on the network (which also downloads stuff quite a lot), the dl speeds are consistently around 50KBps-60KBps. I thought the speeds in UL plans don't go beyond the stated dl speed.

NrN Kill · 09-02-09, 07:55 PM

Quote:

Originally Posted by just4kix

There have been many posts regarding SNR and Line Attenuation.

SNR
SNR means Signal to Noise Ratio. Simply put divide the Signal value by Noise Value and you get SNR. You need high SNR for a stable connection. In general, a higher signal to noise ratio will result in less errors.

6bB. or below = Bad and will experience no line synchronisation and frequent disconnections
7dB-10dB. = Fair but does not leave much room for variances in conditions.

11dB-20dB. = Good with little or no disconnection problems

20dB-28dB. = Excellent
29dB. or above = Outstanding

Note that most modems display value as SNR Margin and not pure SNR.

SNR Margin
You can think of SNR margin as the measure of quality of the service; it defines the ability of the service to work error free during noise bursts.

This is a measure of the difference between your current SNR and the SNR that is required to keep a reliable service at your connection speed. If your SNR is very close to the minimum required SNR, you are more likely to suffer intermittent connection faults, or slowdowns. You need a high margin to ensure that bursts of interference don't cause constant disconnections.

With traditional broadband, the higher the SNR Margin, the better. With MaxDSL the faster speeds are only available as a trade-off with what your line can reliably support. The Target SNR Margin is about 6dB. If your broadband is provided through an LLU (Local Loop Unbundled) network, this target SNR Margin may be as high as 12dB.

Line Attenuation
In gerneral, attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and gauge (which can differ over the length of the cable), the number and location other connection points on the cable.

20bB. and below = Outstanding

20dB-30dB. = Excellent
30dB-40dB. = Very Good
40dB-50dB. = Good

50dB-60dB. = Poor and may experience connectivity issues
60dB. and above = Bad and will experience connectivity issues

Line attenuation also affects your speed.

75 dB+: Out of range for broadband
60-75 dB: max speed up to 512kbps
43-60dB: max speed up to 1Mbps
0-42dB: speed up to 2Mbps+

Please comment on this article.

(and if you give me reputation on this, I shall return the favour)

I have upstream at a better range then downstream... Both use the same cable, if i am not wrong..

Quote:

Originally Posted by just4kix

There have been many posts regarding SNR and Line Attenuation.

SNR
SNR means Signal to Noise Ratio. Simply put divide the Signal value by Noise Value and you get SNR. You need high SNR for a stable connection. In general, a higher signal to noise ratio will result in less errors.

6bB. or below = Bad and will experience no line synchronisation and frequent disconnections
7dB-10dB. = Fair but does not leave much room for variances in conditions.

11dB-20dB. = Good with little or no disconnection problems

20dB-28dB. = Excellent
29dB. or above = Outstanding

Note that most modems display value as SNR Margin and not pure SNR.

SNR Margin
You can think of SNR margin as the measure of quality of the service; it defines the ability of the service to work error free during noise bursts.

This is a measure of the difference between your current SNR and the SNR that is required to keep a reliable service at your connection speed. If your SNR is very close to the minimum required SNR, you are more likely to suffer intermittent connection faults, or slowdowns. You need a high margin to ensure that bursts of interference don't cause constant disconnections.

With traditional broadband, the higher the SNR Margin, the better. With MaxDSL the faster speeds are only available as a trade-off with what your line can reliably support. The Target SNR Margin is about 6dB. If your broadband is provided through an LLU (Local Loop Unbundled) network, this target SNR Margin may be as high as 12dB.

Line Attenuation
In gerneral, attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and gauge (which can differ over the length of the cable), the number and location other connection points on the cable.

20bB. and below = Outstanding

20dB-30dB. = Excellent
30dB-40dB. = Very Good
40dB-50dB. = Good

50dB-60dB. = Poor and may experience connectivity issues
60dB. and above = Bad and will experience connectivity issues

Line attenuation also affects your speed.

75 dB+: Out of range for broadband
60-75 dB: max speed up to 512kbps
43-60dB: max speed up to 1Mbps
0-42dB: speed up to 2Mbps+

Please comment on this article.

(and if you give me reputation on this, I shall return the favour)

I have upstream at a better range then downstream... Both use the same cable, if i am not wrong..

deepmohan · 09-03-09, 02:24 AM

Quote:

Originally Posted by NARENkill

I have upstream at a better range then downstream... Both use the same cable, if i am not wrong..

Yup you are right both use same cable.

can you please post your Statistics -- ADSL over here will make things easier.

The Black · 11-13-09, 09:10 PM

The following are the values from my "modem status" page :

Modem Status

Connection Status Connected
Us Rate (Kbps) 508
Ds Rate (Kbps) 2042
US Margin 24
DS Margin 31
Trained Modulation ADSL_2plus
LOS Errors 0
DS Line Attenuation 13
US Line Attenuation 4
Peak Cell Rate 1198 cells per sec
CRC Rx Fast 0
CRC Tx Fast 0
CRC Rx Interleaved 0
CRC Tx Interleaved 0
Path Mode Interleaved

DSL Statistics
Near End F4 Loop Back Count 0
Near End F5 Loop Back Count 0

Please comment on whether the above values are ideal.
(esp. the US/DS Margins & US/DS Line Attenuation).

What US/DS Margins & US/DS Line Attenuation values
are the best ?

Thanks ...

Router : D-Link GLB-502T V2 ADSL2+
ISP & speed : BSNL DataOne; 256 kbps unlimited data transfer

meetdilip · 11-13-09, 09:45 PM

Your values seem good.

itsmemad · 11-15-09, 12:37 AM

Yes, they are pretty good...

appy.djuetce · 11-17-09, 10:59 PM

My SNR margin varies. it is generally 7.1 downstram and 19 upstram. attenuation is 21.5(500 combo--speed Upto 2 MBPS plan). But when it rains, it goes don and starts to disconnect. What should I do? sometimes I get SNR of 14 when its not raining. So I think rain is the culprit. What will I do in monsoon yaar!

essbebe · 11-17-09, 11:37 PM

Quote:

Originally Posted by appy.djuetce

My SNR margin varies. it is generally 7.1 downstram and 19 upstram. attenuation is 21.5(500 combo--speed Upto 2 MBPS plan). But when it rains, it goes don and starts to disconnect. What should I do? sometimes I get SNR of 14 when its not raining. So I think rain is the culprit. What will I do in monsoon yaar!

Mention your modem model and make.
Check all contacts for oxidisation /high resistance contacts /blackening
Use short cables.
Change MOd mode to GDMT. Uncheck adsl2 +
Check SNR/ATTN when it rains.
Hasty conclusion.
SNR will increase and ATTN will reduce !!

08-17-09, 10:54 AM	#65
Luke Skywalker Jedi knight Join Date: Jul 2009 Location: IBF Age: 21 Posts: 1,818 Rep Power: 5	Rated this thread but kix .Please change definition from signal to noise ratio to power ratio between signal to noise as I said earlier. SNR long form is Signal to noise but it is not definition. It is 10 times log(base 10) of ratio of signal power to noise power. PS: 1. I remember this as I have just studied it in March for my communication exam. 2.Dunno whether I gave rep or not don't want to give again for same. Tell me if I didn't , I will give to it. Last edited by Luke Skywalker; 08-17-09 at 11:11 AM.

11-13-09, 09:10 PM	#73
The Black Junior Member Join Date: Nov 2009 Location: Kolkata Posts: 1 Rep Power: 0	Are my router values ideal ? The following are the values from my "modem status" page : Modem Status Connection Status Connected Us Rate (Kbps) 508 Ds Rate (Kbps) 2042 US Margin 24 DS Margin 31 Trained Modulation ADSL_2plus LOS Errors 0 DS Line Attenuation 13 US Line Attenuation 4 Peak Cell Rate 1198 cells per sec CRC Rx Fast 0 CRC Tx Fast 0 CRC Rx Interleaved 0 CRC Tx Interleaved 0 Path Mode Interleaved DSL Statistics Near End F4 Loop Back Count 0 Near End F5 Loop Back Count 0 Please comment on whether the above values are ideal. (esp. the US/DS Margins & US/DS Line Attenuation). What US/DS Margins & US/DS Line Attenuation values are the best ? Thanks ... Router : D-Link GLB-502T V2 ADSL2+ ISP & speed : BSNL DataOne; 256 kbps unlimited data transfer

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India Broadband Forum

SNR Margin and Line Attenuation - What do they mean?

SNR Margin and Line Attenuation - What do they mean?

Similar Threads

08-15-09, 10:04 PM	#62
hexwiz Junior Member Join Date: Dec 2008 Location: New Delhi/North East India Posts: 91 Rep Power: 1	My last post in this thread was deleted. I'd appreciate if someone could let me in as to why. Thanks

08-15-09, 10:05 PM	#63
mickey Senior Member & Mod Join Date: Jan 2009 Location: Delhi Posts: 3,303 Blog Entries: 3 Rep Power: 8	^^ one cant know the reasons without asking the mods directly.. they always help..

08-17-09, 01:28 PM	#66
just4kix Platinum Member Join Date: Dec 2007 Location: Pune Posts: 8,899 Blog Entries: 6 Rep Power: 19	Changing to Power Ratio will confuse a lot of people as everywhere it mentioned as SNR margin.

08-31-09, 02:12 PM	#68
Xenon Junior Member Join Date: Aug 2009 Age: 20 Posts: 13 Rep Power: 1	Nice ! From what your comparision stats say .. my BSNL connection is outstanding (Probably due to the local exchange being like 400 meters away and new telephone line) (Downstream / Upstream) SNR Margin (dB): 34.0 \|7.5 Attenuation (dB): 18.0 \|6.1 Output Power (dBm): 8.8 \|1.5 Attainable Rate (Kbps): 13720\|1028 Rate (Kbps):2048 \|928 I am a bit confused about the Rate... it say 2048 or 2 Mbps and my plan is 512 kbps =\ which Rate does that number signify =\ ? I suppose attainable rate is the max supported speed by the router.

08-31-09, 08:49 PM	#69
just4kix Platinum Member Join Date: Dec 2007 Location: Pune Posts: 8,899 Blog Entries: 6 Rep Power: 19	^ Attainable rate is the maximum achievable by the ADSL connection. Modem can achieve much more. You actual speed is better ascertained by a speedtest. Do not depend upon the modem results.

08-31-09, 09:28 PM	#70
Xenon Junior Member Join Date: Aug 2009 Age: 20 Posts: 13 Rep Power: 1	Oh, speed test was at speedtest.net was around .9 mbps - .4 mbps (download) and .3-.5 upload. I am veeery happy with the speeds I am getting, although I am surprised by how the dl speed goes upto 80Kbps (max till now) on torrents at times. Even when I am sharing it with another PC on the network (which also downloads stuff quite a lot), the dl speeds are consistently around 50KBps-60KBps. I thought the speeds in UL plans don't go beyond the stated dl speed.

11-13-09, 09:45 PM	#74
meetdilip The Wizard Join Date: Aug 2009 Posts: 903 Rep Power: 1	Your values seem good.

11-15-09, 12:37 AM	#75
itsmemad Alligator Join Date: Sep 2008 Location: Pleasure drome Posts: 3,514 Rep Power: 10	Yes, they are pretty good...

11-17-09, 10:59 PM	#76
appy.djuetce Junior Member Join Date: Oct 2009 Posts: 1 Rep Power: 0	My SNR margin varies. it is generally 7.1 downstram and 19 upstram. attenuation is 21.5(500 combo--speed Upto 2 MBPS plan). But when it rains, it goes don and starts to disconnect. What should I do? sometimes I get SNR of 14 when its not raining. So I think rain is the culprit. What will I do in monsoon yaar!