?
Solved

Understanding SNR Signal to Noise Ratio on Netstumbler.

Posted on 2006-06-25
9
Medium Priority
?
5,231 Views
Last Modified: 2012-08-14
I would like someone to explain to me how SNR can tell me which AP provides the best signal strength.  Ex.  I have to AP's.  
AP1 has:  SNR: 36 Signal -52 Noise -100 SNR+ 48
AP2 has:  SNR: 36 Signal -62 Noise -100 SNR+ 38

I would like to understand what is the optimal state I am looking for.

Thanks
0
Comment
Question by:kapara
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
9 Comments
 
LVL 22

Assisted Solution

by:fredshovel
fredshovel earned 225 total points
ID: 16979867
I can only relate this to SNR in audio, which is a similar principal -- and the most simplistic explanation is that a higher number represents how much higher the signal stands out from the noise -- thus the higher the number the better. It's a ratio based on a reference level between clean signal and the noise -- you want your signal to climb as high as it can above the noise floor.
You don't want noise 'up there' with your signal. You want to bury your noise as low as you can.

Cheers.  
0
 
LVL 77

Assisted Solution

by:Rob Williams
Rob Williams earned 150 total points
ID: 16979960
To add to fredshovel's comments, below is a link to a brief explanation.
http://www.pcmag.com/encyclopedia_term/0,2542,t=signal-to-noise+ratio&i=51330,00.asp
0
 
LVL 2

Assisted Solution

by:XY_GT
XY_GT earned 150 total points
ID: 16980414
AP1 has the best signal strength.

The better signal is shown by the signal value. When the signal value is lower it is better. This is also indicated by the signal to noise ratio, higher is better.

A good resource for this is WikiPedia. http://en.wikipedia.org/wiki/Snr
0
NFR key for Veeam Backup for Microsoft Office 365

Veeam is happy to provide a free NFR license (for 1 year, up to 10 users). This license allows for the non‑production use of Veeam Backup for Microsoft Office 365 in your home lab without any feature limitations.

 
LVL 30

Expert Comment

by:ded9
ID: 16982168
0
 
LVL 5

Accepted Solution

by:
skaap2k earned 225 total points
ID: 16982896
SNR = Signal to Noise ratio,

It is generally the difference between Noise and Signal,

The less noise you have, and more signal, the higher the SNR.

ie, you could have a signal of -63dbm and a noise level of -82dbm, giving you a SNR of 19.
SNR is only an indicator of the quality of the link, and does not guarantee a good connection.

Kind Regards,
Rob
0
 
LVL 1

Author Comment

by:kapara
ID: 16985211
The reason I want to know is I have to get 2 wireless bridges pointing at each other from 1 mile away.  They are currently working but I have a feeling that they are not positioned for the best possible reception.  I was thinking of taking a wifi card with an external antenna and position it in front of Bridge 1 and tring to change the position to find the best reception.  

Thanks
0
 
LVL 77

Expert Comment

by:Rob Williams
ID: 16985255
If you can actually measure, it is well worth doing. Some commercial wi-fi units have built-in diagnostics to do this.
0
 
LVL 5

Expert Comment

by:skaap2k
ID: 16985272
Hi,

Theoretically, you should have equal signal levels on each end (that is the -52 and -62 bit) - All is not fair with wireless though, most cards have a sensitivity of up to -90dbm (-95dbm if you have a good chipset!) so you have plenty of headroom for weather factors to come into play.

Any signal level between -50 and -70 is good, anything lower and you'd want to either look at alignment / antenna size.

Rgds,
Rob
0
 
LVL 77

Expert Comment

by:Rob Williams
ID: 17172784
Thanks kapara,
--Rob
0

Featured Post

Free Backup Tool for VMware and Hyper-V

Restore full virtual machine or individual guest files from 19 common file systems directly from the backup file. Schedule VM backups with PowerShell scripts. Set desired time, lean back and let the script to notify you via email upon completion.  

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When you try to share a printer , you may receive one of the following error messages. Error message when you use the Add Printer Wizard to share a printer: Windows could not share your printer. Operation could not be completed (Error 0x000006…
This article explains the fundamentals of industrial networking which ultimately is the backbone network which is providing communications for process devices like robots and other not so interesting stuff.
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
Suggested Courses

765 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question