From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f171.google.com (mail-we0-f171.google.com [74.125.82.171]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id E9FF320024C for ; Mon, 12 Mar 2012 16:22:50 -0700 (PDT) Received: by werm1 with SMTP id m1so6528277wer.16 for ; Mon, 12 Mar 2012 16:22:49 -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=F0Lse1XJXd0ccYeMm58+7/ZGzKrpnJwlkiqjF6kcBdw=; b=aS5OXSJZgHD1Y3g5YrgoEyGL8Lpv9PwRPt3QC10UVAPEEAofGm8kMq+sE7dftjdxXM oeUwrDT4f6dI7x5Ixa52V+Rs89PZqCHVbSOhmAgiSkGhnuupgC1xuoUDBl09lf33eCQ/ 4dP73i0EZnakiFgw6uDto8lrZ7VhDGzN0OcsY6hJngDZ5Jo0bJYvpxXUfW1cFr+XIyDe qvFN1SgKNthkxgKLEq6gkMj75kc2YZXRgd4tTYfPNpbuIja5+QUtH4192Y3ZaPA0hiat HQOWL9l6CaWMcxNc4G4DyiPPhz/lBjleekBNd0uVek18HgTL/szA57nmOOa/xm5e05ck 89MQ== MIME-Version: 1.0 Received: by 10.180.93.232 with SMTP id cx8mr1966037wib.14.1331594568989; Mon, 12 Mar 2012 16:22:48 -0700 (PDT) Received: by 10.223.151.8 with HTTP; Mon, 12 Mar 2012 16:22:48 -0700 (PDT) In-Reply-To: References: <20120312220623.GB18256@thyrsus.com> Date: Mon, 12 Mar 2012 16:22:48 -0700 Message-ID: From: Dave Taht 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] the serial alternative/radio noise 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 23:22:51 -0000 So in addition to the crypto + gps idea floated earlier I direct you at the 'smile plug', which is also an ideal device for deployment in places without reliable power. http://www.youtube.com/watch?v=3Dr74rKmz-9Qk I have to drop in at stanford soon to check out their progress. Earlier versions of this hardware (see the open-rd) had some interesting connectors available in addition to usb. I don't know if the dreamplug does - the guruplug had such lousy thermals as to rule it out for any usage.... I'm not wedded to the the wndr3800 as the 'reference time ticker beyond the internet edge' for this project, it merely seemed at the time that just plugging in a good gps signal into the deployment via the router I was already using (and bismark uses, as well as what several other network measurement projects are using), which has increasingly well characterized behavior, was the right thing. we certainly seem to have identified a market and price gap between shipped devices with bad time, and devices with good time, but we haven't established that usb with PPS on 'dcd emulation' can be made 'more right', as yet. So I'm kind of looking for ways to get the right parts and evaluate the following without having to do much soldiering, to try and isolate where each of the latency problems are. PPS serial PPS usb kernel pps gpsd w/wo r/t privs under load Stuff like that. I'd like to be able to duplicate hal's weird traces, find a reciever that works even halfway decently indoors, etc, etc. The venus really does look like a nice device. http://www.sparkfun.com/products/11058 On Mon, Mar 12, 2012 at 3:59 PM, Dave Taht wrote: > On Mon, Mar 12, 2012 at 3:06 PM, Eric S. Raymond wrote: >> Dave Taht : >>> I AM curious if there is one of the gps boards we've looked at than >>> can 'just fit' on this header. Or, for that matter, a RTC. >> >> How often do I have to sing the "this kind of customization won't scale" >> song? > > Cats, herding. > > I note that in the early stages of any project, I tend to appreciate > all sorts of blue-sky thinking, rather than tie down to any one goal, > and try to encourage such in others. I guess in part what drives me in > suggesting alternatives (and please note my alternative above was > intended as a lead-in into the noise question more than an actual > suggestion), is that I would like to find markets for a 'new device', > that 'does new stuff', that justifies the manufacturing run, more than > a 'usb gps with hyper-accurate pps and time output' may, as a > differentiator. > > To give an example I've long had an interest in climate change, in > particular, in the lack of good data from equatorial zones. I had > intended while I was still working on my mesh project in Nicaragua to > co-locate weather stations with at least some nodes, (multiple open > source and open hardware alternatives are available, google for them), > and in that case - given that the network might be down or > non-existent, having good time for the samples also seemed good (as > well as a good location indicator! See > http://www.teklibre.com/~d/b4barrios10.kml for an interactive map of > the sites I'd surveyed with my handheld gps below san juan del sur, > Nicaragua). > > http://oscirrus.see-do.org/schematics/schematics.html for one weather > station (this isn't the one I was thinking of at the time, tho) > > Anyway, this is a potential market use-case for the hardware as > discussed thus far. There are no doubt others. > >> >>> Now, I actually brought this up because in looking at this I realized >>> anew what a huge radiator of various forms of electronic noise this >>> is. - 2.4ghz and 5.x ghz radios, and a variety of possible waveforms >>> from the cpu - and I'm curious as to what extent gps is affected by >>> these frequencies. >> >> You and I have observational evidence that it's not an issue even for >> low-end, poorly-shielded hardware, > > I have observational evidence that we have problems with many kinds of > hardware and the cause is undefined, and varies by manufacturer. > > >> -- >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Eri= c S. Raymond > > > > -- > Dave T=E4ht > SKYPE: davetaht > US Tel: 1-239-829-5608 > http://www.bufferbloat.net --=20 Dave T=E4ht SKYPE: davetaht US Tel: 1-239-829-5608 http://www.bufferbloat.net