[time-nuts] question for expert time guys

WB6BNQ wb6bnq at cox.net
Fri Feb 1 04:39:36 EST 2013

Hi Rick,

You would do better putting a small GPS receiver in the mobile and transmit with
a 2.4 GHz Blue tooth transmitter.  The GPS devices can be gotten very small (your
thumb would just about cover it up).  They are also very light and draw very
little power.  That would save you two transmitting and receiving stations.
Clearly the software would be infinitely easier as you would not need to deal
with all the timing issues.

GPS would provide the position information and its time count for each report, if
that mattered.  Some representative GPS receivers can be research at the
following location:


They also have various transmitter devices for blue tooth, WIFI and Zigbee.  You
can view these under the following category:


This is only one place that provides such things for hobbyist.  There are others,
as well as, going direct to the manufacturers for such OEM products.

I do not know if you are aware of it, but and finale product that transmits over
the air may need FCC certification.  Other sections might apply in certain


Rick Harold wrote:

> To time experts/EE's.
> I would like to triangulate a position of a device which moves using 3
> fixed positions devices of known location.
> The idea is to have these operate on 915mhz or 434mhz or 2.4ghz or
> appropriate frequency.
> These two type of devices (fixed and mobile) are all under my control and
> thus customized as needed.
> The mobile device (not a phone, custom device) would be the least expensive
> item.  I'd like a range of 150 feet or better and accuracy of 3 feet or
> better.
> When manufactured these items they can be calibrated in order to adjust for
> any variation in IC's, discrete components etc...
> We can assume for now the temperature is constant 70 degree temperature.
> Cost is the key design factor.
> The general flow is:
>    1. base station 1 indicates we are determining position of device A.
>    2. Each base station 1, 2, 3 take turns pinging the device to determine
> distance.
>    3. A ping consists of (something like, e.g. frequencies as examples)
>         -send 915mhz signal from base station to device
>         -device response ASAP on different frequency
>         -station waits and counts 'time' for return
>         -this is repeated N? times to get best avg/accuracy.
>         -The mobile device does not move very fast
>    4. Since delays of the process on each unit is calibrated the device and
> base station would subtrack that time out from the results.
>    5. obviously with 3 distances we can determine the 2D position of the
> mobile device
> I know the time accuracy is the key to count time =  feet, 1ns.  This
> overall project is not new concept.   How to make it "inexpensive" is key.
> how inexpensive, very ;-)   no OCXO or expensive components like that.
> That's my goal, and I'm looking for help on the design/thought process of
> getting there.
> I am open to a consulting arrangement for a fee, please email if you like.
>  I've worked with 'regular' EE's (I'm a software guy) but this time
> accuracy is too much for them.
> Esp. finding a way to do it inexpensively.
> Thanks for any thoughts.
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