From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x22c.google.com (mail-wm0-x22c.google.com [IPv6:2a00:1450:400c:c09::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 7C05C3B29E for ; Sat, 4 Nov 2017 21:56:25 -0400 (EDT) Received: by mail-wm0-x22c.google.com with SMTP id b9so8036075wmh.0 for ; Sat, 04 Nov 2017 18:56:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=QmNVssegJxj00mtOrkpL/zywWyjQ8Pba0ghBpi/VN8c=; b=gaZERNbxkJfCS9Xx4RoMQ1gW8GziMHChp2Nj/yZn3QeXRVQYd51vKvNAccu1hg2AYw jGTgSdTSASGm0u6L1bsRZ8O/L2XV2hDYt9wAazby38MTUnhp4ZHs6Z7XoaO7YgC3ZC85 kdqQHLTnaOA7hJQ4yWRgOYRPBYNegmDMU2pyA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=QmNVssegJxj00mtOrkpL/zywWyjQ8Pba0ghBpi/VN8c=; b=ND/J0llFDBIG686afPoKrQcLrufx8aT6SmQO4CTsdIdTY5+pJW+Zn4H05HiY6MBseh 9KjdBkLWPDIGta1/s2ZGKbEqM7JYQdaxhHiQLli5tjjl3VYxXECY48rt4y0q9twOvVvG 8FrF7+pIjI+wifMhv41uwmUyk5+q4td939kyCHOFR9CyYSxTgcOj51gNUiiaURWJHJmR tCBD9yI8Fjs/x8z+JT8XZPuv6rxtRdgsdRvzPMb/yj4UljEh4LKdJeCd+Hls9iqQJMlr RmDlyD0ewi0L7/OnmM9SPQzq5a9lJg90S9xwkgp7Y9iO9ApAxZ0VDeGSjwvvOxj305Ez Ghdg== X-Gm-Message-State: AMCzsaVRe62Nc8/9gc2PgQpCSDuAVyDpSv5P2p894QIU4I2n0/eptaX7 kvnWWh1sB0cogj7Tit+hOiHLwEDMGcA8DH2IQq3QeQ== X-Google-Smtp-Source: ABhQp+SrWK6H/mt5e68+Lc4Sj5Mj/QIqGKPxHxWwv4grBzo2RoSsBE+Cy20NSl2h9mqit+3D9IYWcRPq/bG/aCm+gnw= X-Received: by 10.80.154.165 with SMTP id p34mr14964139edb.303.1509846984355; Sat, 04 Nov 2017 18:56:24 -0700 (PDT) MIME-Version: 1.0 Received: by 10.80.186.35 with HTTP; Sat, 4 Nov 2017 18:56:23 -0700 (PDT) In-Reply-To: References: <87tvybm0x2.fsf@toke.dk> <87efpdn2at.fsf@toke.dk> From: Bob McMahon Date: Sat, 4 Nov 2017 18:56:23 -0700 Message-ID: To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Aaron Wood , make-wifi-fast@lists.bufferbloat.net Content-Type: multipart/alternative; boundary="f403045c2d002b0964055d32a5b0" Subject: Re: [Make-wifi-fast] Wiring up a wireless testbed X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Nov 2017 01:56:25 -0000 --f403045c2d002b0964055d32a5b0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Also, Ixia is selling a controllable RF system and it's in early stages. Maybe contact them to see what the market is driving them to build? My guess is their asking price will exceed $100K and has huge margins relative to bill of materials. One could probably work with telemakus and build a few using their parts and sell it for cheaper than the IXIA chassis and still make a nice profit. Bob On Sat, Nov 4, 2017 at 6:50 PM, Bob McMahon wrote: > Try telemakus for variable attenuators and > variable phase shifters. Aeroflex works well to though are a bit more > expensive, e.g. the 8331 > is an > example > > Power dividers, splitter/combiners and butler matrix devices are sold by > multiple vendors. Prices will vary. Unfortunately, prices aren't super > low. But usually it's worth the extra money to get a reliable and > controllable test bed, particularly when one values their time into the > equation. > > Bob > > On Sat, Nov 4, 2017 at 2:48 PM, Toke H=C3=B8iland-J=C3=B8rgensen > wrote: > >> Bob McMahon writes: >> >> > A way I think about is to emulate the "system" in both range/power >> > (attenuation) and in mixing (phase shifts) It's a diagonal matrix fo= r >> > range feeding into an h-matrix for the mixing. A butler matrix can be >> used >> > for the latter if variable phase control isn't required, e.g. you don'= t >> > care about spatial stream relative powers. >> > >> > On adding energy for "random" noise, some knobs of concern are the >> energy >> > detect on the tx and signal floor for the rx. These sources can be f= ed >> > into the same h-matrix through their own d-matrices. This won't repla= ce >> > field tests but helps get closer towards that while providing for repe= at >> > ability. >> >> What equipment would it take to do something like that? >> >> > Also, equally important by my judgment, though not related to wireless= , >> is >> > to synchronize the clocks on the PCs. An oven controlled oscillator a= nd >> > PTP works well towards that goal. >> >> Yeah, already using PTP in my testbed; quite essential for measuring >> one-way delay. >> >> -Toke >> > > --f403045c2d002b0964055d32a5b0 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Also, Ixia is selling a controllable RF system and it'= s in early stages.=C2=A0 Maybe contact them to see what the market is drivi= ng them to build?=C2=A0 =C2=A0My guess is their asking price will exceed $1= 00K and has huge margins relative to bill of materials.=C2=A0

One c= ould probably work with telemakus and build a few using their parts and sel= l it for cheaper than the IXIA chassis and still make a nice profit.=C2=A0<= br>
Bob

O= n Sat, Nov 4, 2017 at 6:50 PM, Bob McMahon <bob.mcmahon@broadcom.co= m> wrote:
= Try telemakus f= or variable attenuators and variable phase shifters.=C2=A0 =C2=A0 Aeroflex = works well to though are a bit more expensive, e.g. the 8331= is an example

Power dividers, splitter/combiners and butler mat= rix devices are sold by multiple vendors.=C2=A0 Prices will vary. Unfortuna= tely, prices aren't super low.=C2=A0 But usually it's worth the ext= ra money to get a reliable and controllable test bed, particularly when one= values their time into the equation.

Bob

On Sat, Nov = 4, 2017 at 2:48 PM, Toke H=C3=B8iland-J=C3=B8rgensen <= toke@toke.dk> wrote:
Bob McMahon <bob.mcmahon@broadcom= .com> writes:

> A way I think about is to emulate the "system" in both range= /power
> (attenuation) and in mixing (phase shifts)=C2=A0 =C2=A0It's a diag= onal matrix for
> range feeding into an h-matrix for the mixing.=C2=A0 A butler matrix c= an be used
> for the latter if variable phase control isn't required, e.g. you = don't
> care about spatial stream relative powers.
>
> On adding energy for "random" noise, some knobs of concern a= re the energy
> detect on the tx and signal floor for the rx.=C2=A0 =C2=A0These source= s can be fed
> into the same h-matrix through their own d-matrices.=C2=A0 This won= 9;t replace
> field tests but helps get closer towards that while providing for repe= at
> ability.

What equipment would it take to do something like that?

> Also, equally important by my judgment, though not related to wireless= , is
> to synchronize the clocks on the PCs.=C2=A0 An oven controlled oscilla= tor and
> PTP works well towards that goal.

Yeah, already using PTP in my testbed; quite essential for measuring=
one-way delay.

-Toke


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