Optimizing a power level for a transmission so that the transmission is receivable at or near a destination, but no farther, is useful for reduced-power transmissions. Taking into account known distance for the transmission as determined by onboard GPS and geographic databases, a power level may be set more precisely. Accounting for atmospheric conditions which may impact transmission as determined by onboard or received measurements of temperature, solar or other conditions may also permit a power level to be set more precisely. An obstruction database may be consulted to determine whether transmissions will degrade due to objects in between the transmitter and receiver, permitting power level, frequency, bandwidth or transmit/receive location to be adjusted accordingly. The techniques may be implemented in any signal transmission scenario including mobile telephones, aircraft, marine or other vehicle radios, mobile devices with Wi-Fi radios for network computing, stationary radios, and other situations requiring communications.