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'[EE] Audio Positioning System (GPS with sound inst'
2008\01\10@134620 by M. Adam Davis

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I've seen the occasional topic on the piclist with this general idea,
but quick searches on the internet don't show that anyone has
succeeded in creating (or opening their hardware/software/notes)

So I'm thinking about making a simple a positioning system using a few
speakers (sounders) placed about the room with a hand-held receiver
that simply times the reception of each sounder's pulse.

To aid in simplicity, the pulses from the sounders will not contain
any coding, will be within human audio range (so cheap speakers and
mics can be used, as well as being a useful demonstration for
listeners), and the sounders will talk to each other via wire so clock
skew doesn't happen over time.  Pulses will be sent out about once a
second, short enough and with long enough gaps inbetween each that
they will never overlap in the region of interest nor will reflections
be an issue (receiver ignores pulses coming too quickly after the last
pulse).

All the receiver has to do is time the pulse reception relative to
each other of the 3 or 4 sounders, and then perform some simple
trigonometry.  4 sounders would allow the receiver to either recover a
clock, or altitude.  Location of the sounders would be fixed in the
receiver so the firmware has to be changed for a different
configuration (simple, easy to develop, I'll complexify later if
desired)

With tones in the kHz range it seems that a very quick & cheap APS
(audio position system) could be made with gross resolution measured
in feet (at least 10 feet, which isn't much since most demonstration
rooms would be smaller than 40x40, but it would be a start and would
give enough information on where to tweak it.)  Again, complexity
could be added in stages - zero crossing/phase detection, information
encoded in the pulses, etc can improve resolution, accuracy, ease of
deployment, etc.  For now, KISS.

At any rate, I'm no analog guru.  I was planning on amplifying the mic
and filtering it for a particular frequency before doing some sort of
AGC/envelope/ASK sensing scheme.  Perhaps mostly in software (ADC) as
future tweaking would benefit from that.  It's been a long time since
my DSP classes though...

What suggestions/ideas/concepts do you have now that you've read
through this?  Keep in mind I want the first iteration to be as simple
as possible while still getting some positioning information on the
receiver.

-Adam

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2008\01\10@142011 by Cristóvão Dalla Costa

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Years ago there was an experiment where people would walk around with a kind
of pulsing device about the size to serve as keychain holder which would
identify them. Then each room in an office would have 3 or more microphones
to identify and locate these people in the room. Then they could do things
like lock their workstations when they´re away, automatically log them into
any computer they sit in front of, unlock doors, find where their workmates
are, etc.

It was developed by ATT labs in the UK, their site is out but I found an
archived copy here:

http://www.cl.cam.ac.uk/research/dtg/attarchive/projects.html

In their projects page click on "sentient computing", "location systems" and
others for more information.

HTH.

On Jan 10, 2008 4:46 PM, M. Adam Davis <spam_OUTstienmanTakeThisOuTspamgmail.com> wrote:

{Quote hidden}

>

2008\01\10@142242 by Brian Kraut

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That is a common way for positioning information for dynamic positioning
systems used for oil rigs and offshore supply boats in the oil fields.  Look
for acoustic positioning systems on Google and you will get some more
information.  Kongsberg is one maker.  Speed of sound is different in the
water of course.

Brian Kraut
Engineering Alternatives, Inc.
http://www.engalt.com

{Original Message removed}

2008\01\10@142847 by Dwayne Reid

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My understanding is that there are several commercial systems
available that do position sensing on a stage using audio and/or RF.

I don't recall the specifics but I'm pretty sure that a search of the
Yahoo Show-Control mailing list archives will have relevant
information.  I *think* that is where I've seen sporadic discussion
regarding the various systems available.

dwayne

At 11:46 AM 1/10/2008, M. Adam Davis wrote:
>I've seen the occasional topic on the piclist with this general idea,
>but quick searches on the internet don't show that anyone has
>succeeded in creating (or opening their hardware/software/notes)
>
>So I'm thinking about making a simple a positioning system using a few
>speakers (sounders) placed about the room with a hand-held receiver
>that simply times the reception of each sounder's pulse.


--
Dwayne Reid   <.....dwaynerKILLspamspam@spam@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2008\01\10@194117 by Nate Duehr

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Cristóvão Dalla Costa wrote:
> Years ago there was an experiment where people would walk around with a kind
> of pulsing device about the size to serve as keychain holder which would
> identify them. Then each room in an office would have 3 or more microphones
> to identify and locate these people in the room. Then they could do things
> like lock their workstations when they´re away, automatically log them into
> any computer they sit in front of, unlock doors, find where their workmates
> are, etc.

There are also systems that did this for automated camera tracking on
stages, and for presentations for videoconferencing.

Most of them today use IR instead.  Speaker clips a little IR sender to
their body, usually part of a lapel microphone so it shouldn't really
ever be "blocked" to two or three IR receivers.

I think the IR solution is probably more elegant than an acoustic one.
Less filtering needed to filter out noise, echos, etc... unless you have
a lot of highly light-reflective surfaces in the view of the receivers.

Nate

2008\01\10@195320 by M. Adam Davis

face picon face
A brief look at the group site brings up the following system:
http://www.martin.com/specification/specification.asp?product=lightingdirector&subgroup=Tracking+Systems

Ultrasonic with predictive tracking, 5cm (2").  Pretty cool.

-Adam

On Jan 10, 2008 2:28 PM, Dwayne Reid <dwaynerspamKILLspamplanet.eon.net> wrote:
{Quote hidden}

2008\01\10@200049 by M. Adam Davis

face picon face
I assume they would use IR cameras then?

-Adam

On Jan 10, 2008 7:41 PM, Nate Duehr <EraseMEnatespam_OUTspamTakeThisOuTnatetech.com> wrote:
{Quote hidden}

> --

2008\01\10@201926 by Nate Duehr

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M. Adam Davis wrote:
> I assume they would use IR cameras then?

I don't know -- I believe the system I saw demoed once (wasn't able to
get my hands on it, just saw it tracking in a very big room) had the IR
receivers on top of the cameras, but since many CCD devices can "see" IR
... maybe the CCD's in the camera are also used to follow the tracking
device.

Wish I could have gotten up close and personal with the cameras to see
the telltale signs of an IR receiver window in the top or something.

Very cool to watch a three camera system follow a speaker around.

It did a pretty good/smooth job, and for an event where they didn't want
to pay camera operators and wouldn't mind a little "camera lag" when a
speaker was moving around, it would have worked pretty well.

The room I saw it demoed in was a giant lecture hall, and the system
wasn't "installed" so I again assume that the IR receivers are on the
cameras themselves, and then straight to the pan/tilt/zoom control
hardware.

(Yeah, thinking back, it did also seem to know somehow how to track a
person moving "fore and aft" on a deep stage, also, including framing
their body with zoom by zooming out as they walked forward and zooming
in as they walked backward.  Must have been some interesting code to
write...)

Nate

2008\01\10@210812 by M. Adam Davis

face picon face
The wii remotes can do that, and in fact it would be fairly easy to
tape a wii remote to a PTZ camera and control pan and tilt so the IR
light is always in the center of the Wii sensor.  The zoom would be
easier with two cameras (or a second wii remote) to do a little
triangulation for depth.

http://www.cs.cmu.edu/~johnny/projects/wii/

Looks like Johnny Lee's next project is 3d tracking.  He keeps making
me want to pick up a few Wii remotes...

-Adam

On Jan 10, 2008 8:19 PM, Nate Duehr <natespamspam_OUTnatetech.com> wrote:
{Quote hidden}

> -

2008\01\11@044935 by Alan B. Pearce

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>The wii remotes can do that, and in fact it would be fairly easy
>to tape a wii remote to a PTZ camera and control pan and tilt so
>the IR light is always in the center of the Wii sensor.  The zoom
>would be easier with two cameras (or a second wii remote) to do a
>little triangulation for depth.
>
> http://www.cs.cmu.edu/~johnny/projects/wii/
>
>Looks like Johnny Lee's next project is 3d tracking.  He keeps making

Hey, that is real clever. The 3D demonstration in the 3rd movie is really
something.

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