Your code is most impressive. Using timer1 is inspired.
I can't take credit for that... My original code for receiving the signal was horrible. GitHub - kayno/ThermorWeatherRx: Arduino based Thermor/BIOS wireless weather station receiver and practicalarduino.com did most of the RX logic.
Your descriptions of the protcol are well set out.
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From your work I would'nt mind betting that you have also had some teaching experience.
If one of the developers i work with where to put a design spec on my desk as hastily created as my OS V3 protocol discriptoin id make them do it over again 
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