[ale] My Raspberry π is here
Michael H. Warfield
mhw at WittsEnd.com
Wed Oct 17 14:59:55 EDT 2012
On Wed, 2012-10-17 at 13:50 -0400, Ron Frazier (ALE) wrote:
> Hi Mike W,
>
> Your message made me think of a specific application for the pi that I
> have need of. I have to maintain my Dad's Windows Vista computer. He
> lives in Jasper. I can drive up there to do things and do so
> periodically. That also give us the opportunity to have lunch, etc.
> However, it's nice to be able to do things by remote control. I can
> already do this with a Windows application called CrossLoop, kind of
> like Go To My PC, etc. That works OK if Windows is working and all
> the communications stuff is working. However, I cannot reboot that
> way and I cannot manipulate the BIOS. Dad has to help me get logged
> into the machine.
> I need a fully encrypted remote kvm. It would sit between the pc and
> it's monitor, mouse, keyboard, and router; and would, once I'm
> properly and securely authenticated, transmit all kvm signals back and
> forth to me. It should also allow local pass through so the original
> keyboard, mouse, and monitor still are usable. That way, I could
> reboot the machine if necessary, and even get into the BIOS. Nice to
> have features would be remote control of the power outlet, status
> information for the power outlet, remote control of the power and
> reset buttons, and a visual light signal at his location to indicate
> when I'm connected. He should be able to switch off the remote
> connection at any time if desired, in case anyone nefarious breaches
> the security. I may even want a key switch to be turned on at his
> site to enable login, although being able to log into the machine when
> he's not even there would be helpful. The ability to transfer files
> back and forth would be very helpful. I suppose I could start
> Crossloop once I boot up, but that seems a bit kludgy. The interface
> between my machine and his needs to be fully graphical without any
> cooperation from the OS on his system.
> I know such things are on the market, but they are quite expensive.
Yes they are. I have some Ascend IP KVM's that are crazy expensive for
one of my labs.
I strongly suspect you may have a problem with your desire for it to be
pass-through where it sits between the computer and the associated
keyboard/video/mouse device allowing you to share simultaneously. I'm
not really sure what might be on the market available for such an
application. I have a Digi Passport I-KVM single port IP KVM that was
reasonable in price, when and where I bought it, but it doesn't support
the kind of passthrough you would be looking for.
http://www.digi.com/products/consoleservers/digi-passport-i-kvm#overview
They price out at at several hundred up at CDW but can be had cheaper if
you shop around. Still... Big owwie. I think I found one somewhere
for under $100 but that was some time ago and I will not attest to how
well it works. It's not the most reliable device in my setting.
Certainly, with USB, you have the potential of handling the keyboard and
mouse if you can get a host-mode emulation going with the keyboard and
mouse coming into the RP and running a keyboard mouse emulation out to
the computer. It's doable. If it's doable on android (and we have it)
it's doable. To do it with the PS/2 interfaces - I wouldn't even
attempt it. Video can be challenging on one front but may even be
easier in other ways. A USB video capture device could be used to
passively capture the screen output. You could use a VGA to component
adapter, along with some sort of sharing device. Video capture at any
decent resolution is going to be VERY processor intensive, though.
Anything more than NTSC or PAL resolution and you're going to need
something beefy like the Hauppauge HD PVR or better. There's another
pricey toy (I have one). That's about $170 at Fry's last I looked.
> By the way, I like the idea of the power disturbance analyzer.
> Available bandwidth may be a problem, depending on what the highest
> harmonic you want to measure or the shortest spike. If the sensor pod
> had it's own micro controller and USB port, you could probably get
> much higher bandwidth. It would be interesting to tie some of the
> sensor pods from the PC based O-Scope products to the pi and run some
> DSP algorithms or something like matlab on the pi. I think some of
> those sensor devices or probe devices use USB.
Well, bandwidth should not be a major problem. Most audio capture will
handle from about 30Hz up to maybe 20KHz two channel without breaking a
sweat. I don't even particularly care where the 3dB points are because
it can always be equalized in software and I'm probably just going to
feed it straight into an FFT anyways. If I wanted to reach up into the
MHz range, one of the digital O-scope pods would be nice but would be
overkill in bandwidth and, quite frankly, weak in resolution. The
reasonably priced ones are only 8 bits per channel. Admittedly, 24 bits
per channel is overkill from an audio capture but I would rather have
more resolution. It may not catch X-10 120 KHz signals or Insteon at
131 KHz but I would have to filter them out of the data anyways.
Voltage spikes I'm not really concerned about too much as far as
measuring them goes, only detecting them.
If I compare this to say a Dranitz Line Disturbance Analyzer (my
existing one died may years ago and it's too expensive to replace for
such little use) I think it has the potential to do as well or better...
> Sincerely,
> Ron
This is good though. This is really what we need. Brainstorming ideas
we can put these things to work for. I like your KVM idea... May take
some work but hell yes!
Regards,
Mike
> "Michael H. Warfield" <mhw at wittsend.com> wrote:
>
> >On Wed, 2012-10-17 at 10:11 -0400, Derek Atkins wrote:
> >> "mike at trausch.us" <mike at trausch.us> writes:
> >>
> >> > On 10/16/2012 04:05 PM, Scott Castaline wrote:
> >> >> Finally got my π today and wifey wasn't here to grill me, so I'm a
> >> >> very happy camper! Happy, happy, happy! Playtime now begins. Even
> >the
> >> >> FedEx guy has already been playing with one already.
> >> >
> >> > They are wonderful little things.
> >> >
> >> > I ordered 5 after last month's meeting so that we could play with
> >them,
> >> > and I am already looking at putting them to use to solve some
> >> > long-standing problems that these are just absolutely perfect for
> >solving.
> >
> >> Okay, what long-standing problems are they absolutely perfect for
> >solving?
> >
> >I can come up with several just off the top of my head.
> >
> >Easy:
> >
> >*) A "little black box" with ssh keys, cron, and highly restricted
> >access do manage remote server operations and interserver
> >communications
> >using key auth forwarding over ssh.
> >
> >*) A security storage module holding CA keys or PGP keys much like a
> >smart card might due but higher capacity, higher performance, and lower
> >cost.
> >
> >*) A remote serial console driver to monitor servers. Sort of an add
> >on, out board, server management module.
> >
> >*) Server monitor. Drop it on a remote network running nagios and
> >health checks against your bigger servers.
> >
> >*) Logging server. Have it running rsyslogd and just saving syslog
> >events off the local network to the SD card where it can't be tampered
> >with by intruders who can't reach it.
> >
> >Because they're cheap, you can use lots of them as embedded controller
> >devices for for small specialized tasks like these.
> >
> >A much more difficult straw man idea I've been wrestling with:
> >
> >(This one I believe Mike T will relate to immediate based on some of
> >our
> >recent discussions...)
> >
> >How about a DIY power line disturbance analyzer? Take your AC power
> >line signal (both phases) and divide it WAY down (say 1000:1) so it
> >fits
> >within range of an audio signal. If you're not really concerned too
> >much, some nice resisters will do along with some micro-fuses and
> >transorbs. If you are paranoid about playing with high voltage, some
> >linear opto-isolators are even better, just more complicated. Now feed
> >those two signals to the stereo input of a USB audio adapter. It's
> >just
> >a 60Hz signal, after all, with the two phases 180 degrees out of phase.
> >Most ADC (analog to digital converter) daughter boards I'm seeing for
> >the RP are two slow for what I want (15 samples per second for a 16 bit
> >8 channel board is NOT going to hack it).
> >
> >Now you can monitor and measure things like...
> >
> >* Surges
> >* Sags
> >* Spikes
> >* Dropouts
> >* High frequency noise (notch for X10 and Insteon if desired)
> >* Frequency
> >* Voltage
> >* THD (Third-order Harmonic Distortion)
> >* Imbalances
> >
> >Basically the things that a decent line disturbance analyzer does only
> >without the $10,000 price tag. Commercial units I've worked with will
> >handle more phases and more inputs at higher voltages, are hipot (hi
> >potential) tested and isolated for workplace safety, and are often
> >calibrated and tracible back to NIST standards, which are not
> >necessarily things we need (hipot isolation is desirable to protect the
> >device but may not be necessary as a safety feature do to more limited
> >voltages in the home). That could be in the price range where you
> >install it near your breaker panel and just leave it there and download
> >data occasionally.
> >
> >You can not measure things outside of the audio range of the device.
> >Things like DC offsets and very low frequency that an ADC could measure
> >but are generally not of serious concern.
> >
> >Add another audio input and some induction picks and you could add
> >current monitoring. Another audio input and you can have neutral to
> >earth ground (common mode) monitoring. Some nice beefy batteries can
> >keep it going through some long power failures. With enough on-board
> >horsepower to do a decent FFT and you could store large amounts of
> >signal data and events.
> >
> >Yes, I've read the articles indicating that audio input to the RP has
> >been less that sterling (sucks? still?) and may be rather
> >problematical. That's something I really want to test and compare to a
> >more general purpose device.
> >
> >> > --- Mike
> >
> >> -derek
> >
> >So... Those are just a few ideas.
> >
> >Anyone else?
> >
> >Regards,
> >Mike
> >
> >> --
> >> Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
> >> Member, MIT Student Information Processing Board (SIPB)
> >> URL: http://web.mit.edu/warlord/ PP-ASEL-IA N1NWH
> >> warlord at MIT.EDU PGP key available
> >>
> >> _______________________________________________
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> >> Ale at ale.org
> >> http://mail.ale.org/mailman/listinfo/ale
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> >> http://mail.ale.org/mailman/listinfo
> >>
>
>
> --
>
> 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
>
>
--
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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