Re: prism2 silence value question

Rob,

I've had a similar experience with some of my cards.. My older prism2 cards
(smc 2632w v8r3) and my senao 200mw prism2.5 card will not report any
(accurate) noise values. Whereas, my milan prism2.5 card (under the sticker
it says prism 2.5 reference card) reports accurate noise values. I'm
guessing that it might be something that intersil forgot to implement
originally and finally got around to implementing it properly.

Additionally, I remember reading somewhere that the signal/noise/quality
values are calculated based off of the ratio of good packets to crc err
packets. If that's actually true, it might be possible to implement noise
ratings on the software end. Just a thought.

-h1kari


On 1/28/03 13:12, "Rob Deker" <[email protected]> wrote:

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> 
> Maybe somebody out there can help me noodle this one out (you listening
> h1kari? ;)
> 
> I've been writing some code for a project that looks at the signal/silence
> values from prism2 cards, and I've hit one somethign interesting. I was
> initially doing my coding against a Netgear MA401 prism2.5 card that
> probes out (under OpenBSD 3.2) like this:
> 
> wi1 at pcmcia0 function 0 "NETGEAR MA401RA Wireless PC, Card, ISL37300P"
> port 0xa400/64
> wi1: PRISM 2.5 ISL3873, Firmware 1.0.7 (primary), 1.3.6 (station), address
> 00:09:5b:24:0b:fd
> 
> Seems simple enough, it's an ISL3873-based card. For any given sample of
> packets here in my lab, I see silence values ranging from ~3 through ~10,
> which seemed to directly contradict a lot of people's driver code that
> asserts 27 as a floor value for the silence byte (dstumbler included). In
> some testing, I noted that I was seeing packets with my code that were
> being discarded by dstumbler because of a silence value < 27. I thought
> this was odd/nifty/whatever and hadn't mailed here about it because I
> hadn't gotten around to it.
> 
> I recently got my hands on a Demarc 200mw Prism2.5 card (which I have to
> say is SWEET), and I'm seeing something that's confusing me a bit. The
> demarc card probes out like this:
> 
> wi0 at pcmcia1 function 0 " , IEEE 802.11 Wireless LAN/PC Card, " port
> 0xa000/64
> wi0: PRISM 2.5 ISL3873, Firmware 1.0.7 (primary), 1.3.6 (station), address
> 00:60:b3:75:ae:3d
> 
> My values for silence however are (again, in my lab) ranging from ~30 to
> ~38 on average. This roughly seems to bear out the floor value of 27 that
> a lot of people seem to use, but I'm confused as to why I'm getting these
> different values from 2 cards with the same chipset and firmware versions.
> 
> Any thoughts from the peanut gallery?
> 
> Alternately, any suggestions on a good way to normalize the data I'm
> getting so that either card would be useful?
> 
> thanks,
> 
> 
> - -d
> 
> "You see, wire telegraph is a kind of a very, very long cat.
> You pull his tail in New York and his head is meowing in
> Los Angeles. Do you understand this? And radio operates
> exactly the same way: you send signals here, they receive
> them there. The only difference is that there is no cat. "
> 
>                                          --Albert Einstein
> 
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