From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vx0-f171.google.com (mail-vx0-f171.google.com [209.85.220.171]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id D403920024C for ; Mon, 12 Mar 2012 14:22:30 -0700 (PDT) Received: by vcbfl15 with SMTP id fl15so8718679vcb.16 for ; Mon, 12 Mar 2012 14:22:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=9irjj4nOPHh+RGhUquXMfcJisTLv6g8Gb2iSLELvdbU=; b=n3sJpMIQHPEuE/00sLDKaatoDrgOOYgCsRJTJ1oivE3D4DQ77TyvdkZzQmzF04joR9 b9zmantFcvZ7cY7Yv5MBnpvrcZnHWsRQ40rZ+aKyEhW2JhdYp4OtcYm4s8CSqOMD6p5e OFB+YLbjFdZjyUF1HNqw1ntI9qp34MqzPbA/8Mu7kQ5IFX12nisPrOQpchX+WmigB10W ABr5cneYIorgTp4uedDn92HkmKqAlnXnzT438umNGWRKKIELsbJTBDFYlfoEoRfKAAvm KmPbH3QNDVrBqOo4zTFvZnmXTiBBusb+bL7Zq3QhCuA6Pcec0ILmUa/TkItqyrkYnMpI liVQ== MIME-Version: 1.0 Received: by 10.52.36.226 with SMTP id t2mr15439969vdj.52.1331587349797; Mon, 12 Mar 2012 14:22:29 -0700 (PDT) Received: by 10.220.140.132 with HTTP; Mon, 12 Mar 2012 14:22:29 -0700 (PDT) In-Reply-To: <20120312210345.GC17357@thyrsus.com> References: <20120312210345.GC17357@thyrsus.com> Date: Mon, 12 Mar 2012 16:22:29 -0500 Message-ID: From: Patrick Maupin To: esr@thyrsus.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: thumbgps-devel@lists.bufferbloat.net Subject: Re: [Thumbgps-devel] Build vs. modify vs. what should we be doing anyway? X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Mar 2012 21:22:31 -0000 On Mon, Mar 12, 2012 at 4:03 PM, Eric S. Raymond wrote: > I'm still skeptical about custom builds for production - means one of us > would have to do the soldering, keep inventory, ship the results. =A0I'd = rather > develop a design and talk SparkFun or Dangerous Prototypes into fabbing i= t. But if you work with somebody like this or like seedstudio, they will order parts for you and assemble according to your instructions. If you simply view the dongle as a part to be ordered and the assembly to be "take it apart, add this blue wire, put it back together" you will realize that the same process could apply, at least for a company that does more than basic board assembly. > But an advantage of starting with this $23 module is that we don't have > to make that decision yet. Exactamundo! > [Test system] sounds like a larger project than just reverse-engineering = the dongle, > though. =A0Do you have the capability, personally, to design and build su= ch > a thing? This is more what I do on a daily basis. Use a bunch of readily available off-the-shelf thingies to make a few units. In this case, I would buy a third party FPGA board, make a couple of smaller PCBs to talk to it with a socket for an OCXO, maybe a connector to accept a clock from a rubidium time source, headers for some USB modules and some GPS modules and do some FPGA coding to allow reliable high resolution timestamps. There are a couple of levels of this. The first is just to do some one-off futzing around looking at various devices. The second is to get serious. You could probably build 3 identical units with really good resolution and stability (expensive OCXO) for under $2K total. Maybe a lot less if you can find some good surplus stuff on ebay. > And this makes complete sense. =A0Seems like a good way to start that doe= sn't > require excessive time commitment up front on your part. In that case I'll start ordering and plotting out what I'm going to do, and will sign up for the project to start putting out information on the test setup for people to throw rocks at.