mini wireless

One way or both (simplex or duplex ?)

If, as I'm assuming, your data is going from the "small" unit to a distant base, then I'd probably recomend an OOK transmitter on the 433MHz ISM band. SAW resonators can be had in 3x3mm packages, and a two transistor oscillator + buffer circuit will probably do

Myk, (I also read your columns in EWW): 433 MHz is in the centre of the 430 - 440 MHz radio / T.V. amateur band, and the carrier frequency for ATV is 434.250 MHz; we have enough various applications of "low power" status (here, that's 10mW maximum) that interfere with our research efforts as well as each other, so I would really recommend the 868 MHz transmitter solution which suffers far less and affects other users less as well in my professional as well as amateur experience (I was a Space Electronics Engineer especially involved (in the ground segment) with telemetry distribution using a  UHF link series.

Another common consumer problem arises too from the 433 MHz usage - older car-door-keys that use this range for locking / opening of car doors, I've seen occasions of people "hopping mad" because their "car door won't work" when near an ISM transmit source, which is often not referred to the 10 mW limit but maybe around 100mW or so, 10dBm above what is supposed to be allowed but is not policed effectively in any way most of the time.

Just my own views and experience - Trevor Gale.

Myk, (I also read your columns in EWW): 433 MHz is in the centre of the 430 - 440 MHz radio / T.V. amateur band, and the carrier frequency for ATV is 434.250 MHz; we have enough various applications of "low power" status (here, that's 10mW maximum) that interfere with our research efforts as well as each other, so I would really recommend the 868 MHz transmitter solution which suffers far less and affects other users less as well in my professional as well as amateur experience (I was a Space Electronics Engineer especially involved (in the ground segment) with telemetry distribution using a  UHF link series.

Another common consumer problem arises too from the 433 MHz usage - older car-door-keys that use this range for locking / opening of car doors, I've seen occasions of people "hopping mad" because their "car door won't work" when near an ISM transmit source, which is often not referred to the 10 mW limit but maybe around 100mW or so, 10dBm above what is supposed to be allowed but is not policed effectively in any way most of the time.

Just my own views and experience - Trevor Gale.

I found these

http://www.laipac.com/gps_rf_components.htm

Is there anything smaller?

Hi R_P,

Well, if you want smaller physical size, then you might look at the Nordic NRF24L01GNRF24L01G+ http://www.sparkfun.com/products/690 , however you'd need to do work to add an aerial etc, like this: http://www.sparkfun.com/products/152. You'll find some cool NRF24L01GNRF24L01G+ options at a cheaper price on eBay too, however they are "bigger". The bigger profile "ready made" boards might help you to learn/ prototype.

Another option along these lines is the Texas Instrument chips: eg. the CC2530, CC2540, etc http://focus.ti.com/analog/docs/rfifcomponentshome.tsp?

What mirocontroller are you using? If you're new to wireless and are using Arduino, then you might want to do some hands on research first. The 1MW Xbees (e.g. element14: XB24-AWI-001XB24-AWI-001) would arguably be the easiest place to start. They simplify a lot of the comms management you'll need to do with the cheaper 433Mhz RF options, and there are lots of code libraries and examples available for xbee. Of course, they are "bigger" and they cost more .

SeeedStudios RFBee is also another interesting option http://bit.ly/gLlztW with its built in Atmega168 AVR. So, as its AVR is combined, this might help you with size.

If 868 or 915Mhz appeal, then the JeeNode might be a good prototyping choice: http://jeelabs.com/products/jeenode.

Cheers,

Paul