Date: Tue, 23 Aug 2005 10:59:31 -0500 From: Sam Pierson <samuel.pierson@gmail.com> To: Sam Leffler <sam@errno.com>, FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Global txpower in ath Message-ID: <d9204e4c05082308597437589@mail.gmail.com> In-Reply-To: <42FACAF6.4020805@errno.com> References: <d9204e4c05081010537d65972@mail.gmail.com> <42FACAF6.4020805@errno.com>
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On 8/10/05, Sam Leffler <sam@errno.com> wrote: > Sam Pierson wrote: > > I noticed that when I control the signal strength through > > ifconfig, I can effectively reduce the signal when I set it > > as something like: ifconfig ath0 txpower 1. I have read > > that this input is device driver dependent and I couldn't > > find anything in the interface that handles txcontrol. Are > > these values taken in exactly or are they rounded to some > > less fine-grained control number? Thanks, >=20 > The current support has a limited number of settings for the tx power. > I don't recall how many there are but it's chip dependent and possibly > also frequency-specific. 5212 parts are capable of controlling txpower > on a per-packet basis but getting it "right" has proven very hard and is > not yet supported. >=20 > Sam >=20 I read that the Atheros chipset supports up to 60 different txpower options and like you said, it seems to be limited, to about 45 different settings at this point (ie: only txpower 1-45 are respected). The thing that has been bothering me is that the card is supposed to be capable of transmitting at like -90dBm (practically nothing, only good for=20 communication at a few meters with normal wireless cards) and at its lowest power setting, transmits like a -50 or -60 dBm signal. This ends up going like 60m before any significant signal loss. Are there _any_ cards at this point which support a global variable rate txpower and can transmit a signal only good for a few meters? Or is the support for these cards just not at that point yet? Even the cisco cards that I tried, which can supposedly transmit at 101 different levels, send like a -60dBm signal at its weakest strength. -Sam
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