From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x230.google.com (mail-wm0-x230.google.com [IPv6:2a00:1450:400c:c09::230]) (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 304673B29E for ; Sat, 4 Nov 2017 21:50:26 -0400 (EDT) Received: by mail-wm0-x230.google.com with SMTP id z3so7964240wme.5 for ; Sat, 04 Nov 2017 18:50:26 -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=Wx+zhxAosd/e3arO5CNkKNbZDBwLeyo6CG+VrY5DyXs=; b=IUWQwelzzVl+VscGdLa7yQJMT6pxW2meZMoEoFlhsmp5bW8Xj60pTlp9pmQIpEulkS q8LO3X3cdTYQ5Kgabx2tzlM4cdyaUJzH41du+l8bU3uQwDACCAAA1MLkraXYoGr/nIIq YO+mIRn3nrn/tfzQjuYUmOXPUxy/JxhEAG3Lo= 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=Wx+zhxAosd/e3arO5CNkKNbZDBwLeyo6CG+VrY5DyXs=; b=uIXm2cHhdzPBeIP+B1cafTzsy5hY+8p+ZUe9DjTF1srj74smbOtLYSJJerFjt59dfY DPmMQdpOqKrK/ztsY4By8kzgV2tXNSXRXiTBG8nx28XbakcRs1tdH7D923d8CSHn9eag PfZkKWdOuW/R3rx+3Z3dO8hGxJdRQ9XzuFufDipDYG8xUUnVJPuF2lhU+Esc1FpZHSg5 W0hWaT6MGbR6REvMLWtdwT2gmMd9Pbt8JRlj44tmX2DgJ94yqEUgnNTrjHQXY0O87BzV jKByDzQ3IonhQnhTyNWJSXzTsho/A/Pbr3/Miu3AgPOiEUF5UYudNE+FrvaWQQWo2jfx +VAQ== X-Gm-Message-State: AMCzsaXMWnfUe5EDNmPxtUR04EJnZrJcAu70ZfP7X6uDtvJYVd8g06J9 mXbGfmfVqZ8lBFqXPguoICoFik1kLU84oyyRgufFVg== X-Google-Smtp-Source: ABhQp+RVCr9E4Zye+Xqn9KYuQD8qwaK8WfhZByxYb4XukAhZXHoCIvMRZSRUHDkJSm9ivTgvfAYFdLfbvl13WQJgQuA= X-Received: by 10.80.168.129 with SMTP id k1mr14808124edc.109.1509846625051; Sat, 04 Nov 2017 18:50:25 -0700 (PDT) MIME-Version: 1.0 Received: by 10.80.186.35 with HTTP; Sat, 4 Nov 2017 18:50:24 -0700 (PDT) In-Reply-To: <87efpdn2at.fsf@toke.dk> References: <87tvybm0x2.fsf@toke.dk> <87efpdn2at.fsf@toke.dk> From: Bob McMahon Date: Sat, 4 Nov 2017 18:50:24 -0700 Message-ID: To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Aaron Wood , make-wifi-fast@lists.bufferbloat.net Content-Type: multipart/alternative; boundary="94eb2c195950c0957b055d328fc2" 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 01:50:26 -0000 --94eb2c195950c0957b055d328fc2 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 for > > 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 ener= gy > > detect on the tx and signal floor for the rx. These sources can be fe= d > > into the same h-matrix through their own d-matrices. This won't replac= e > > field tests but helps get closer towards that while providing for repea= t > > 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 an= d > > PTP works well towards that goal. > > Yeah, already using PTP in my testbed; quite essential for measuring > one-way delay. > > -Toke > --94eb2c195950c0957b055d328fc2 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Try telemakus fo= r variable attenuators and variable phase shifters.=C2=A0 =C2=A0 Aeroflex w= orks well to though are a bit more expensive, e.g. the 8331 is an example<= br>
Power dividers, splitter/combiners and butler matrix devices are sol= d by multiple vendors.=C2=A0 Prices will vary. Unfortunately, prices aren&#= 39;t super low.=C2=A0 But usually it's worth the extra money to get a r= eliable 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=B8= rgensen <toke@toke.dk> wrote:
<= span class=3D"">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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