Hi All,

I'm close to my EE. BSc finale and I'm looking to play around a little bit with the stuff I've learned. To be honest, I'm a little bit upset that afer 4 years of learning communications theory, I'm not able to choose the HW I need.

My idea is to reach a half duplex walkie talkie with the following reqs:

-Low voltage operation. Till 5V.
-Range about 1.5 km LOS
-ISM frequency use ( I preffer 433 MHZ UHF bands )
-Single chip that doesn't require extra elements as crystal or filters

The idea is to intstall 2 walkie talkies, one on each house. House are about 900m range. One has a direct window outside while the other is an interior office.

The application is for voice only. Cosidering the FM advantages I'll prefer it, but if there is a big difference of value then AM could be an option.

The chip I'm looking for must be smallest that can be.

I've seen many chips ( as the following links ) but I'm not sure that their digitals buffers support voice applications..

http://www.hoperf.com/rf_fsk/fsk/21.htm
http://www.melexis.com/Wireless-Multi-Market--Sensing/RFIC-Transceivers-27-to-950MHz/TH7122-121.aspx
http://www.silabs.com/products/audio/fmtransceivers/Pages/default.aspx

Thanks !

 

in the uninted states, 433 isnt an ism frequency, its primary useage is government radiolocation (high power radar) ham radio and part 15 unliscensed devices.
check in the newark catalog, they have 433mhz tranciever part kits and modules.
cliff