Bob, The original implementation was done on a Sanyo 5800 series CMOS 4 bit processor that was used for watches and small PDA's and in this case store labels. the processor was used because it was low power and an internal gate array that was designed to drive LCD segments. It will take some looking for the implementation notes here, its here we moved and the old mental index doesn't work here. The basic implementation sync'd the serial data with the carrier frequency. The carrier was 32.768Kz. I can't remember the data rate carrier /8 or 16 maybe / 32. The data was manchester encoded so the carrier did a 180 deg shift on a data transition. The links were half duplex bi-directional with a range of about 300 feet in an electrically noisy environment . The transmitter consisted of two output pins on the micro that always complimented each other to drive the tuned circuit that served as an antenna. Data was added by exoring 11 with the port mask that was being output. Input used the same two pins and a software detect of the phase shifts . The system had a low data rate and enough redundancy to be quite reliable. It also had a layer of error correcting in the protocol. When I get a chance I will pull notes. We used a similar system on a wireless transmitter that reported data out of an instrumented tooth brush (forces and direction information for a research project) w.. Bob Blick wrote: > On Wed, 17 Sep 2008 17:26:49 -0400, "Walter Banks" > said: > > The Tx/Rx had everything in software. > > > > Yep bit banged RF > > That is way cool. I'd love to actually do something like that. Is there > any documentation or more info around? > > Thanks, > > Bob -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist