Is it possible to build GPS "like" system for high-accuracy local position finding?

If you can live with fairly poor accuracy and can have more transmitters, your life will be easier. If the receiver has a good signal from 3 transmitters and your transmitters all share the same reference time base, the phase relationship between carriers gives you a fine resolution continuous function of position.

Wood and sheetrock act enough different from free space to be a problem to the system. I see no reason you couldn't add more transmitters if needed to solve this however.

Ultra sound is fine unless there is a wind.

I see you have a few years spare... ;^)

Here is an open source GPS design based on a rather obsolete RF frontend and correlator IC:

That's a starting point. You may be able to adapt it to a different frequency band and modulation scheme to improve accuracy.

Also read the GPS documentation. The civilian stuff is freely available.

This one practically tells a seasoned EE professional how to build a receiver:

Kind regards,

Iwo

FOUND SOLUTION!!!!

I found what I was looking for. "Indoor position tracking" was the key search in google. Duh!

It is pretty accurate 1 - 2 cm. This will have to do!! Uses ultrasound and RF.

This is opensource software and hardware, as they give the circuit diagrams along with parts list.

My only question now is, can you assemble this with a saudering iron?

Parts are around $50 bucks, I'm going to try!! Wish me luck.

Crossbow technologies sells them assembled, but at $225 a peice, I'm going to try building one myself.

The price is very cheap, but $50 is a whole lot cheaper!!

I'm pretty excited about this, thankyou for all the advice.

EVERYONE I FOUND A SOLUTION!!!!

I found what I was looking for and the price is right!!! "Indoor position tracking" was the key search in google. Duh!

It is pretty accurate 1 - 2 cm. This will have to do!! Uses ultrasound and RF.

This is opensource software and hardware, as they give the circuit diagrams along with parts list.

My only question now is, can you assemble this with a saudering iron?

Parts are around $50 bucks, I'm going to try!! Wish me luck.

Crossbow technologies sells them assembled, but at $225 a peice, I'm going to try building one myself.

The price is very cheap, but $50 is a whole lot cheaper!!

I'm pretty excited about this, thankyou for all the advice.

NOTE: This is a double post, and I am sorry.

I know you have found a solution, but here's a thought.

Instead of 'n' static transmitters and 1 mobile receiver, how about using 1 mobile transmitter and 'n' receivers? That should be easier to calibrate and less prone to reflections.

Have fun :o)

Mike

The ATMega is available either of two 64-pin packages, neither of them all that easy to work with on a breadboard.

Best regards, Spehro Pefhany

Sure they're pretty big SMD AFAICS.

Well, huh ... You need to design the PCB first because I didn't see it on they're site. And it will most likely be a 2 layer PCB so you have to add that to the price.

And there is the time it will take you to do it.

Sylvain

Here is my reasoning:

For initial prototyping phase, I'll need five crickets. $5 x 225 = $1125

For the second phase prototype, I'll need 30 - 50 crickets ~$6750 to $11250. But I'd imagine getting a discount at that quantity, so this isn't accurate. My point is, I need a lot of these things.

If I could design the PCB, (which I currently have NEVER done) and solder them by hand, this would save a HUGE amount of money.

It would take a long long time for me to do this, but I have lots of time and no money.

Finished product size isn't a huge issue, so I'll make them bigger then they are when you buy them. This will make it easier for me to create them.

A couple of ICs have a lot of pins. (20 - 50). Do these guys have "seats" or "connectors" so I do not have to try to solder the IC directly?

I'm researching this plenty but any advice is a great help.

I have played with that idea, but my object in motion, needs to know his own coordinates in the space. Somehow this would have to be trasmitted back to him.

I guess that is possible though and the problems I'd face would seem easier then doing it the other way.

I'm hoping just to solder everything and skip the breadboard alltogether. Does it have some kind of "seat"? Are their universal seats for many pin IC's like this?

I'm still looking...

Well, sure you can. But solder 30-50 units is kinda boring ;)

The schematics is fairly easy, shouldn't take too long. Of course if you don't already know any CAD program, that may take some time.

As an advice : the harder is to place the component so that the connection are easy to make. Since you have a photo of a finished product just use their placement ;)

The bigger it is, the expansier the PCB will cost. For 50 units that should be < 7.5$ per PCB.

??? that's not that hard to solder, it has a pretty big pitch, hard to screw up with a good iron (and if you're planning on doing 50 units, you have to buy one ;).

Just look up on the net how to solder SMD's properly. (try 'hand smd soldering').

Sylvain

Warehouse? Whorehouse?

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

A "wharehouse" sounds like a place to keep old politicians after they have finished plying their trade.