[ale] possible meeting topics - ODB / NTP-GPS - And more...

Sat May 26 14:38:40 EDT 2012

As long as we're on the topics of topics...

Based on recent threads, discussions, and presentations...

Robust DNS deployment and management or more.

Grub2 themeing.

Multiboot USB (related to grub2).

I might be able to do one or two of these in the future (just not in the
next couple of months).

I've seen a couple of other threads in the channel that could be
developed into good talks and presos.  We got some good stuff here,
people!

Regards,
Mike

On Sat, 2012-05-26 at 13:47 -0400, Ron Frazier (ALE) wrote:
> Hi all,
> 
> At the risk of opening a big can of worms for myself, I'd like to
> mention two potential meeting topics, which, if there is interest, I'm
> willing to do presentations on.
> 
> The first, which I've put a fair amount of time and energy into, and
> which I've mentioned in a previous thread, is using the OBD (onboard
> diagnostics) system of a car in conjunction with an android tablet to
> display virtual automotive gauges reading the car's vital statistics
> and show the results on the screen of the tablet. This is very cool,
> and, when I mentioned it before, there seemed to be some interest in a
> presentation. The one potential hitch in doing such a presentation, is
> that I cannot bring the car into the classroom. Therefore, I need an
> OBD-II simulator, which I can plug my OBD scanner into, and thus show
> what appears to be live data to the group. I don't know where to get
> such a thing, so, if anyone does, please let me know.
> 
> PS I'm not using the OBD scanner in my car as much as I was. I
> discovered that the MPG estimates, which were one of my primary
> purposes, are extremely inaccurate. You can put a fudge factor in the
> program to compensate, but then you have to measure your MPG the old
> fashioned way first.
> 
> The 2nd thing, which I've invested several months learning about, is
> using NTP with GPS to run my own time server. I am nowhere near an
> expert on the topic, however, I am happy to say that I now have a (non
> public) fully cross platform stratum 1 NTP time server running at my
> house using GPS with PPS as a time source and providing time service
> to the PC's on my LAN. GPS time is maintained by the DOD to within + /
> - 100 ns of UTC as far as I know. So that's + / - .1 us. My time
> server maintains its time to within + / - 30 us or so. The accuracy on
> my NTP clients' side is variable, depending on the load on my wifi,
> and runs from a few ms to a bit more.
> 
> What I'm somewhat proud of, and what was not easy to learn how to do,
> is that I've made everything totally cross platform. The NTP server
> runs and reads the GPS and serves time whether it's booted into
> Windows or Linux, using a different software stack, I might add, but
> still NTP. (Sorry Mac people, I don't have a Mac.) Also, the clients
> access the server whether they are booted into Windows or Linux. Not
> only that, the server may boot on either of two wifi routers I have,
> using two different wifi adapters, and everything still works. That
> presents problems because the server gets different IP addresses from
> the different routers. Getting all these various permutations to work
> was very complicated and tedious.
> 
> As with the OBD stuff, the hitch is caused by the classroom. There is
> no way to get GPS signals in there. So, I need a GPS simulator. If
> anyone knows how to do that, please let me know.
> 
> I did have a thought along those lines. Rather than simulating the
> radio waves the GPS device receives, we could simulate it's output.
> The NMEA output of a GPS is nothing but a bunch of ascii text on a
> serial communications port coming in at typically 9600 baud. The text
> includes coded information strings which specify things like time,
> latitude, longitude, data for satellites being tracked, etc. Suppose
> we were to simply capture all the output from the GPS for a few days
> into a file. If we could create a virtual com port, then we could dump
> the contents of that file into the virtual com port at 9600 baud. The
> NTP program could read the virtual com port, and it would think it's
> attached to a GPS. That could serve as an independent simulated time
> source.
> 
> I see two potential problems. First, the PPS (Pulse Per Second) pulses
> would not be appearing at the DCD line of the virtual com port, and
> therefore, the PPS functionality of NTP would be dormant. Second, the
> time stamps in the recorded data stream would not agree with the rest
> of the world. So, if we let the NTP server communicate with any
> servers in the outside world, it might mark the GPS as a falseticker
> and ignore it.
> 
> Please let me know what you guys think of these topics as
> presentations, and how we might be able to arrange the technology so
> it will work in the classroom. If anyone wants to collaborate with me
> on a joint presentation, I'd be glad to have the help.
> 
> Sincerely,
> 
> Ron
> 
> 
> --
> 
> Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9 Mail.
> Please excuse my potential brevity.
> 
> (To whom it may concern. My email address has changed. Replying to former
> messages prior to 03/31/12 with my personal address will go to the wrong
> address. Please send all personal correspondence to the new address.)
> 
> (PS - If you email me and don't get a quick response, you might want to
> call on the phone. I get about 300 emails per day from alternate energy
> mailing lists and such. I don't always see new email messages very quickly.)
> 
> Ron Frazier
> 770-205-9422 (O) Leave a message.
> linuxdude AT techstarship.com
> 
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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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