STARTUP power up wake up gps get cold gps fix sleep gps set rtc time from gps calculate time to next transmit window go to sleep LOOP wake up [30] seconds before transmit window wake up gps get hot gps fix sleep gps update rtc time from gps calculate grid locator and assemble message(s) go to sleep wake up at start of transmit window (+/-) enable tcxo/radio transmit wspr message(s) disable tcxo/radio calculate time to next transmit window 10 minutes from now go to sleep POWERDOWN Save some data in eeprom? ???