On 25/08/11 13:20, Marko Vojinovic wrote:
> On Thursday 25 August 2011 16:06:28 Bob Goodwin wrote:
>> On 25/08/11 10:43, Marko Vojinovic wrote:
>>> On Thursday 25 August 2011 13:24:00 Bob Goodwin wrote:
>>>>> Clients
>>>>> MAC Address Interface Uptime TX Rate RX Rate Signal
>>>>> Noise SNR Signal Quality
>>>>> 00:1E:52:86:4B:C3 eth1 N/A N/A N/A -42 -88 46
>>>>> 64%
>>>>> B8:FF:61:35:AC:CC eth1 N/A N/A N/A -52 -88 36
>>>>> 52%
>>>>> 00:1F:1F:A5:D6:84 eth1 N/A N/A N/A -62 -88 26
>>>>> 39%
>>>>> 00:AA:BB:CC:DD:10 eth1 N/A N/A N/A -67 -88 21
>>>>> 33%
>>>>> 0C:EE:E6:84:F3:A9 eth1 N/A N/A N/A -55 -88 33
>>>>> 48%
>>>>> 00:11:85:8C:CC:25 eth1 N/A N/A N/A -61 -88 27
>>>>> 40%
>>>>> 00:02:6F:9B:BA:C4 eth1 N/A N/A N/A -42 -88 46
>>>>> 64%
>>>>> 00:1D:73:C9:11:94 eth1 N/A N/A N/A -57 -88 31
>>>>> 45%
>>> I'm confused --- there is the "Signal" column, the "Noise" column, and
>>> the "SNR" column which apparently has nothing to do with the ratio
>>> between signal and noise. In addition, how is the "Signal Quality"
>>> estimated?
>> I'm sorry, the lines were "wrapped" messing up the formatting.
>>
>> There are four numbers of interest, Signal, Noise, SNR, and
>> Signal Quality.
>>
>> Signal quality is expressed as a percentage. For instance the
>> first line shows the series
>> -42 -88 46 64%
>>
>> The received signal level -42 dbm
>> The receiver noise level -88 dbm
>> Signal to noise ratio 46
>> Signal quality 64%
>>
>> I did not create the system, I am merely a user but that's is
>> how I interpret it.
> I'm not complaining about formatting. What I don't understand is why is SNR
> equal to 46, and not to the ratio of signal to noise, ie. 42/88, which is not
> 46, but 0.47? Or take the next row in your table: signal: -52, noise: -88,
> SNR: 36, quality: 52%. However, the ratio of signal to noise is 52/88 = 0.59,
> which has apparently nothing to do with the given SNR value 36, nor with the
> signal quality of 52%.
>
> How am I supposed to understand these numbers if the "Signal to Noise Ratio"
> is not equal to the ratio of signal to noise? :-)
>
> Furthermore, if the ratio between signal and noise does not represent the
> overall quality of the signal, how is the "signal quality" parameter measured?
>
> Is there some explanation about the definitions of the columns in that table?
> And can you tell me what tool did you use to generate these numbers? Maybe
> there's some explanation in its man page, and besides I am sort of interested
> in using some tool to measure the geometry of my own wireless net here...
>
> P.S. Sorry for hijacking the topic from the OP... ;-)
>
> Best, :-)
> Marko
>
They are simply taking the difference between the noise and
signal and calling that the signal to noise ratio. A signal at
-42 dbm is much stronger than the noise level down at -88 dbm,
the difference is 46 db. I don't know if that is a valid noise
figure or not but it seems to me that that's what they are doing.
As I said in the original post this is displayed in the data
provided by DD-WRT. And once more I simply use it, I have no
part in its development. This must be derived from data
available in the Linksys router.
My point was that the receiver quality was probably more
important in most cases than increased transmitter power.
Bob
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