An operational low cost system is developed for mapping daily and monthly mean daily global solar radiation reaching the ground over a big geographical area from APT (Automatic Picture Transmission) images of NOAA polar orbiting satellite. The system is suitable for use in south and southeast Asia and is said to be acceptable for engineering, agricultural, and climatological applications requiring the knowledge of geographical and temporal variation of solar radiation. It is alterable for use in other locations. The system comprises a personal computer attached with a small APT receiver along with other peripherals such as monochrome monitors and simple printer. An improved empirical bispectral method which applies visible and far infrared APT images is used to calculate the cloudiness of the sky. The empirical coefficients obtained by correlating cloudiness with ground measured solar radiation are used to estimate solar radiation at a target on the ground knowing the cloudiness of its sky from a satellite image. The geographical coverage of the map can be as big as 15 degrees latitude by 20 degrees longitude near the Equator. The spatial resolution of the radiation map is 111 km. The mean standard error of estimation of daily global radiation is 12.9% with a range of 6-19% of the measured mean. This accuracy is acceptable and comparable to other similar methods developed so far.