First Post

I had this mad urge to brag about what I am doing, so, well here is this site.
Maybe couple of months from now, looking back, I will remember why this thing is taking me so long.

Anyways, the current history up till now:

My first design was going to be an FM controller, in the standard 72-73MHz range. Given the fact that there are 50 channels in the range, which should be software selectable, forces to build a complex processing system. I couldn't find anything off the shelf, so building involved a standard PLL, 10kHz reference frequency (from a counter powered by a Pierce oscillator at 10.24MHz crystal). The PLL should produce a frequency in the range of 2MHz to 3MHz. This can be mixed with a 70MHz reference (i.e. use frequency multipliers to generate). The mixer can double up as a power amplifier (Class D I think). The channel is selectable though the counter chip from the processor. (A lot of my research on frequency synthesis came from this wonderful website: http://web.telia.com/~u85920178/ ) The main problem then lay in designing a custom VCO. With back to back varactors for channel selection and message modulation, the problem is just selecting the right values for the components.
After several months of part-time fiddling with the circuit and trying to get spice to work on Linux or Windows, I scrapped the whole design to the garbage bin... I had several reasons: I am notentirely sure if my design is solid nor the tooling and research time to verify it. On top of that, modulation has to be done with a 8B/10B circuit so that PLL does not loose frequency lock (Not something exactly built into a PIC processor). I would be interested to know if the design idea was complete scrap or not. On other hand, I am happy to share more info about this design, if you are doing something similar.

My new design!!!

I found this nifty module called XBEE that communicates over the new ZigBee standard in the 2.4GHz ISM band. The module communicates over standard UART protocol, plus several pins for extensions. The modules are reasonably priced and have been tested for a decent distance. Whether this module will be fast enough to keep up with the controller is something I will have to find out by trial. The XBEE-1 boasts from a 115 kbs while I think I can encode all of my data into 1kbs stream.
With this module, the communication is bidirectional, so no worrying whether the battery is dying on the model, the controller will know in due time.
The plan is to build the circuit around this module, and ensure extensibility for later additions.