From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bifrost.lang.hm (mail.lang.hm [64.81.33.126]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5737C21F40B for ; Sun, 21 Dec 2014 00:28:18 -0800 (PST) Received: from asgard.lang.hm (asgard.lang.hm [10.0.0.100]) by bifrost.lang.hm (8.13.4/8.13.4/Debian-3) with ESMTP id sBL8S8Jg021790; Sun, 21 Dec 2014 00:28:12 -0800 Date: Sun, 21 Dec 2014 00:28:07 -0800 (PST) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: "Mike O'Dell" In-Reply-To: <6764.1419109075@ccr.org> Message-ID: References: <6764.1419109075@ccr.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] Cerowrt-devel Digest, Vol 37, Issue 24 X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 21 Dec 2014 08:28:47 -0000 On Sat, 20 Dec 2014, Mike O'Dell wrote: > 15.9bps/Hz is unlikely to be using simple phase encoding > > that sounds more like 64QAM with FEC. > given the chips available these days for DTV, DBS, > and even LTE, that kind of processing is available > off-the-shelf (relatively speaking - compared to > writing your own DSP code). per the chart at http://ubcdn.co/media/images/product-features/spectral-efficiency-image.jpg (part of the link above), they use up to 1024 QAM (although the peak rate is listed at 64 QAM) I also wouldn't be surprised if their claim for 15.9bps/hz is the aggregate of both directions at once. David Lang > keep in mind that the reason the 2.4 and 5.8 ISM bands > are where they are is specifically because of the ready > absorption of RF at those frequencies. the propagation > is *intended* to be problematic. that said, with > good-enough antennas mounted with sufficient stability > and sufficient power on the TX end and a good enough > noise floor on the RX end, one can push a bunch of bits > pretty far. > > Bdale Garbee (of Debian fame) had a 10GHz bent-pipe repeater > up on the mountain above Colo Spgs for quite some time. X-band > Gunnplexers were not hard to come by and retune for the > 10GHz ham band. i believe he just FM'ed the Gunnplexer > with the output of a 10Mbps ethernet chip and ran > essentially pure Aloha. X-band dishes are relatively > small and with just a few stations in the area he had fun. > > -mo > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel >