Did you mean:. All forum topics Previous Topic Next Topic. Message 1 of Acceptable Noise Margin. As per the title , what is an acceptable noise margin in HH5 stats? Message 2 of Re: Acceptable Noise Margin. Message 3 of Quiet line test seems normally quiet tbh. Message 4 of Can you post lines from the HH stats page? Message 5 of Looks like this may have been a temporary glitch.
Things seem to be returning to normal. Noise margin 6. Message 6 of Noise margin has nothing to do with dB. Noise margin is how much noise you can have 1V, 2V, 2. That's not the proper unit or method for determining noise margin, you're talking about something unrelated to noise margin- though I don't know what the proper way to refer to it is. High noise margin means quiet room and you can whisper to one another.
Low noise margin means noisy room and your whispering would be drowned out. You'd keep losing track of the conversation and having to repeat yourself to get the message accross; analogous to resending packets and losing sync. That's exactly what it's been stated in the FAQ.
Some is right, some is wrong. The higher is the better. This is indeed the actual "Volume" of carrier signal. Most Modems do not display this value. The higher is the better, but explanation in article is wrong. An "SNR margin" of 1 or 2 may synchronize your modem correctly. It shows up the dB of Signal! I also wouldn't recommend this but this may work. You will have no buffer. It could be much more, this is what you read.
Annex J becomes quite common in Europe. Modem link speeds are allowed to be handshaked by both sides to the max possible speed. Therefore you'll get way lower SNR margin. Noise margin in a digital circuit is different than the noise margin on an analogue line.
ADSL modulation takes the digital 1s and 0s in your computer and converts them into analogue signal suitable for sending down a phone line. That's why you measure it in dB - it's an analogue signal when it's on the line.
In response to the idiotic notion that decibels are nothing to do with Noise Margin in DSL communication circuits:- In communications system engineering, noise margin is the ratio by which the signal exceeds the minimum acceptable amount. Noise Margin in circuits is the amount of noise that a circuit can withstand. Noise Margins are generally defined so that positive values ensure proper operation, and negative margins result in compromised operation, or perhaps outright failure.
Most of you have it half right. Snr is the ratio of useful signal compared to background noise. Snr margin is the extra signal strength needed to overcome the noise the noisy room is a good example, the lower the Snr, the quieter you can talk. Noisy lines need a bigger margin. Broadband is a trade-off between speed and stability. A higher Snr margin means the dslam actually msan these days has to do more work so, although the line is more stable, it is slower. Generally a margin increase of 1dB will drop sync speed by about 3mbps.
I could have got those numbers backwards. The dlm at the exchange adults bigger margins when multiple losses of sync are detected, giving a slower, more stable connection.
Before people wade in to argue, I'm a broadband support agent with one of the UK's biggest Bb providers, and deal with this daily. But to answer the question, UK lines aim for a margin of 3dB, most are stable at 6db, anything over 12dB is worrying and will be very slow. Thanks for actually answering the question! Could you please advice how to manage the noise margin, like if the noise margin is very high 31db how can we minimize and what is the possible impact.
Thank you. A few notes: 1 dB is not a unit, it's simply a way to look at things in a logarithmic scale. Instead of saying , , , I could say 20 dB, 30 dB, 60 db. The common use of dB when discussing noise is due to the high amount of variability in signal and noise amplitudes, which would otherwise necessitate use of cumbersome numbers.
It could be high because noise is low, which is a good thing. The British engineers looking to minimize SNR are relying on persistently high noise to look at the signal-to-noise ratio as a measure of the signal's amplitude, which is a really bad practice because some lines have less noise, and because they could simply look at the amplitude of the signal directly instead. My ISP provider is BTand since this happened the hub has disconnected the internet for about 1 minuet, it does this about every 8 hours or so on and have been advised that it can take up to 5 days to stabilize.
Can you please advise thanks. I found the "opposite" opinions on whether the SNR margin is better high or low confusing. I did some reading in Wikipedia and I came to the conclusion that the reason for the opposite opinions is likely due to an assumption of what the SNR margin is representing. By my reading the SNR margin is negotiated between the subscriber ADSL device and the provider and represents the percentage of the theoretical data throughput that will be used.
Sorry, guys, but I am of the opinion that a low SNR is bad, and a high one is good. Perhaps you are mistaking SNR for attenuation? With attenuation, higher dB's is good and low dBs is bad. My ISP's system backs this up. These types of lines are in use in video surveillance systems that utilize PoE Power over Ethernet cameras.
As a person who has installation experience with systems of this type, I can attest to the cost-effectiveness of the technology. And before ADSL, there was dial-up utilizing our phone lines for internet access. Although Fiber in many areas supplants the use of this technology as a whole, it still has its place in specific markets. The parameters that govern ADSL functionality include:. Speed: We refer to this as the channel rate of the connection to the DSL-switch.
Also, this consists of two speeds, Download to the customer and Upload from the customer. Furthermore, a higher value equates to better signal quality. Signal Power Level: It is a reference to the output power. In other words, it is the output power of a signal at the instant of modem synchronization with the DSL-switch. In general, the standard output power is approximately 10 dBm sending data.
Signal Attenuation: This refers to the signal attenuation in the line at the instant you achieve modem synchronization with the DSL-switch. Overall, this value should be less than 45 dB.
As a rule, a higher value means a lower signal quality and slower data speeds. When we refer to signal attenuation, we consider a value of 5 dB to 30 dB to be optimal, and above 45 dB to be unacceptable for ADSL use. After understanding these basic characteristics of ADSL, you can then move into how to design around characteristic vulnerabilities.
As you can see, several parameters govern the functionality of ADSL, and specific parameters are more detrimental to functionality than others, for example, noise margins.
Although our signals do not originate from the planet Krypton, the weakening effects of exceeding the recommended noise margins are no less accurate. As I am sure you are aware, these margins represent the measurement of the line quality and define a minimum limit at which the signal level is above the noise level. The minimum noise margin limit for data transmission is 6 dB, and a value lower than this will not support a stable ADSL connection.
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