ChillyGoose
@sofsa.mil | Noise, Attenuation and Power Margin
I am new to the DSL world and noticed Noise Margin, Attenuation and Power db levels. What are acceptable levels and when should I be concerned? Can I do anything to optimize my DBs?
I have a 2wire 2701HG gateway.
Thankx in advance. |
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Gwai Lo Dan
join:2007-01-24
St Catharines, ON
 ·CIKTEL Telecom
| I am no expert, but no one replied. I did read that upstream + downstream divided by 18 is approximately the distance to the DSL equipment (CO or remote), and 5 km is about the limit. Someone can now add in!!
In terms of what you can do, have simple wiring! No 100 foot phone cords - stay with the standard 6 foot cord. If you need more distance between the jack and the phone, put the modem close to the jack and run cat5/6 wire from the modem to your computer. |
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muiredised
ESSE QUAM VIDERI
join:2007-06-11
Tacoma, WA
1 edit | reply to ChillyGoose
said by ChillyGoose :
I am new to the DSL world and noticed Noise Margin, Attenuation and Power db levels. What are acceptable levels and when should I be concerned? Can I do anything to optimize my DBs?
The "Noise Margin" is related to the Signal-to-Noise Ratio (SNR). Your line requires a minimum SNR in order to deliver a specified speed. The Noise Margin is the difference between your actual SNR and the SNR required to deliver the specified speed. Since SNR fluctuates the Noise Margin can be thought of as a buffer zone. An example, if your line requires 30dB SNR in order to deliver 10mbps and the actual SNR of your line is 38dB then the Noise Margin is 8dB. The higher the value the better. I've seen this table before.
6dB or below is bad
7dB-10dB is fair
11dB-20dB is good
20dB-28dB is excellent
29dB or above is outstanding
Attenuation is a measure of the signal loss that happens as a result of the distance between your modem and the exchange. The lower the value the better. Attenuation is logarithmic and each 3dB of attenuation halves the strength of the signal power received. A line with 30dB of attenuation only receives 1/1,000th of the original power. A 60dB line would only receive 1/1,000,000th.
20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor
60dB or above is bad
said by ChillyGoose :
Can I do anything to optimize my DBs?
You can somewhat affect your Noise Margin. Using good quality, shielded cabling, and eliminate sources of noise. What introduces noise to your line? Anything that produces an electromagnetic field, hence all modern technology.
Attenuation is mostly beyond your control unless you move closer to the exchange.
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