The same thing we do every night, Pinky...

Archiver

Fellow High Stampers,

I've noticed a recurring theme among recent posts is how to implement
some sort of arbitrary location tracking system, within a fixed area
(race track, flat panel display, front yard).

While IR is always a possibility, I distinctly recall way back in the
1980s seeing a number of location tracking systems in development
which could accurately detect the location of an object radiating an
RF field of a particular frequency, in 3 dimensional space. What
happened to those?

Do we have *any* form of off-the-shelf or better yet, inexpensive,
method of detecting the location of an object based (2d on a plane or
3d, either will do) on either RF or magnetic field strength or
interference?

If not, anyone have any links to research in this field or somewhere
that I could start looking for info on it?

I think many people would benefit from this info.

Thanks,
-Chilton

Archiver

2-D and 3-D ultrasonic position tracking has been used since the early
1980s, with analog electronics and specialized microphones. A system
called the Grafpen used a spark source sonic emitter on the moving object,
with external microphones for localization. Magnetometry requires external
field coils, and works only within a restricted 3-D space. Both types of
systems are quite expensive.

Dennis

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Original Message

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From: <chilton@t...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, March 19, 2001 11:00 AM
Subject: [noparse][[/noparse]basicstamps] The same thing we do every night, Pinky...


> Fellow High Stampers,
>
> I've noticed a recurring theme among recent posts is how to implement
> some sort of arbitrary location tracking system, within a fixed area
> (race track, flat panel display, front yard).
>
> While IR is always a possibility, I distinctly recall way back in the
> 1980s seeing a number of location tracking systems in development
> which could accurately detect the location of an object radiating an
> RF field of a particular frequency, in 3 dimensional space. What
> happened to those?
>
> Do we have *any* form of off-the-shelf or better yet, inexpensive,
> method of detecting the location of an object based (2d on a plane or
> 3d, either will do) on either RF or magnetic field strength or
> interference?
>
> If not, anyone have any links to research in this field or somewhere
> that I could start looking for info on it?
>
> I think many people would benefit from this info.
>
> Thanks,
> -Chilton
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Archiver

Take a look here: http://www.naturalpoint.com/prod/product.htm

A pair of simple vision sensors somewhat like TrackIR was used to build a
2-D tracking system that covered most of a large room. The moving target
has to have a bright IR emitter (LED) that's visible from all angles, and
there must be no other bright IR sources within the sensor fields of view.
I was involved in TrackIR development, and I was told that the vendor has
published an application programmer's interface...

>> I've noticed a recurring theme among recent posts is how to implement
>> some sort of arbitrary location tracking system, within a fixed area
>> (race track, flat panel display, front yard).
>>
>> While IR is always a possibility, I distinctly recall way back in the
>> 1980s seeing a number of location tracking systems in development
>> which could accurately detect the location of an object radiating an
>> RF field of a particular frequency, in 3 dimensional space. What
>> happened to those?
>>
>> Do we have *any* form of off-the-shelf or better yet, inexpensive,
>> method of detecting the location of an object based (2d on a plane or
>> 3d, either will do) on either RF or magnetic field strength or
>> interference?
>>
>> If not, anyone have any links to research in this field or somewhere
>> that I could start looking for info on it?

Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!

Archiver

I happened to be thinking a bit more about this question... Without doing
any research, I bet those RF-based systems used phase measurement to
establish position of a relatively low-frequency source on the moving target.

In order to eliminate phase ambiguity, a single wavelength has to cover the
entire tracking area. This puts the transmit frequency in the neighborhood
of 10MHz (30m wavelength) for many applications. Two receive antennas are
needed to establish receive angle (in a phase detector) albeit with 180
degrees of uncertainty. A third receive antenna is likely needed to
establish absolute distance and resolve the 180 degree uncertainty. The
mobile transmitter is just a stable CW (sine) source. Phase detectors are
relatively simple circuits, and the necessary trig calculations could be
done by a Stamp with some help from a math coprocessor.

A posible problem with this scheme: Unless you have an amateur radio
license, there may be no suitable and legal transmit frequencies available...

>> I've noticed a recurring theme among recent posts is how to implement
>> some sort of arbitrary location tracking system, within a fixed area
>> (race track, flat panel display, front yard).
>>
>> While IR is always a possibility, I distinctly recall way back in the
>> 1980s seeing a number of location tracking systems in development
>> which could accurately detect the location of an object radiating an
>> RF field of a particular frequency, in 3 dimensional space. What
>> happened to those?
>>
>> Do we have *any* form of off-the-shelf or better yet, inexpensive,
>> method of detecting the location of an object based (2d on a plane or
>> 3d, either will do) on either RF or magnetic field strength or
>> interference?
>>
>> If not, anyone have any links to research in this field or somewhere
>> that I could start looking for info on it?


Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!