How small can you make a cell phone?
 

and it doesn't have to be a cell phone. Just needs to be transmit GPS location data.

I think it would be limited by ergonomic considerations (size of buttons limited by fingertip size?) and probably battery technology because GPS transmitters tend be quite hungry. I'm guessing something around the size of an IPod Shuffle?

Breitling once made an Emergency Transmitting watch that had a pull out aerial that could only be used once before being sent back to the factory for resetting.

So again something watch / IPod Shuffle sized i would think.

Just a guess...

This:

https://www.sparkfun.com/products/10138

Is your cell phone transmitter, can send the data via SMS.

This:

https://www.sparkfun.com/products/10922

Is your GPS reciever.

Put the two on the same board and give it power from a small lithium cell and you're good to go.



If you designed the boards from scratch with just the bare essentials from those boards above needed for your specific application, even smaller.

And if you ditch transmission by cell phone signal and go with something local-based, even smaller still.

Thanks Mike, that's exactly what I want.

Would not want to go with local/personal area networks.

Any ideas on what it would take to add wireless charging?

Adding wireless charging to any phone

Induction charging still requires some pretty small distances between the charger and the device.

There is another form of wireless power transmission technology that uses magnetic resonance instead of induction, but I haven't seen anyone using it.

Depending on how often if it programmed to send data, a small lithium battery could power the device for a very, very long time. Essentially, if you only wanted to track on object's position once a day, it could be in a low power standby mode almost all the time, and only turn on to parse the GPS data and send it. I'd say over a month.

Intel has developed a product that is a SOC, memory, I/O, sensors, wireless, power management, in a single package (looks like a single "chip", though probably has multiple semi die inside), less than 1" x 1". Not sure if it has radio amp/tx/rx included. I heard it includes battery too but not sure I believe it. That's small.

And Google Glass is another very small device.

Very cool, thanks again. Yes, when charging, you would just put it on your desk to charge. No plugging in.

I'd like dual connectivity between any given smart phone and the transmitter.

I'd like secure bluetooth and/or wireless connectivity such that if the transmitter moves outside of your personal area network, the phone sends an alarm. This would be programmable so that you aren't getting false alarms.

If I and my phone are in NYC and the transmitter is in Boston, I'd like to know exactly where the transmitter is in Boston.

The package limitation for a GPS device that can transmit over GSM networks isn't the size of the chip, the microprocessors. The act of taking the raw timing info from the GPS signal, converting it to position, and parsing it for a text message... can be done on a bit of silicon the size of a pea now.

The package limitation for this device will be antenna interfaces, power & signal conditioning- these are solid state objects that are still limited in their fundamental size, although major advances in antenna tech have been happening over the last 10 years.

Google glass isn't quite a good benchmark as it requires pairing with a phone for it's data connection to the outside world via cell signal (unless that has changed recently, but I think that is the case). But take away the camera and eyepeice and add a cell module like the data module I linked to above, and you're right on target.

Then the only package driven becomes battery size- how long you want it to run on a single change.

So I have to marry peas (silicon) and carrots (antenna) with a wafer thin battery.

The spot tracker is pretty compact, but as mentioned earlier the battery size comes into play determining the size

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