The SDR-1 Single Detector Rotating Shadowband Radiometer is identical to our standard Multifilter Rotating Shadowband Radiometer (MFR-7) except that it has a single cosine-corrected broadband silicon channel that provides fully automatic measurements of global, diffuse, and direct normal components of solar radiation. It is very similar to bolometric/thermopile type radiometers except the spectral response of silicon does not extend as far into the mid infrared. Historically, a total solar pyranometer has been integrated with a solar tracker-mounted normal incidence pyrheliometer and a third shaded pyranometer to make these measurements, as is done in the Baseline Solar Radiation Network. However, the SDR-1 offers a simpler and less expensive alternative than these separate instruments. Because it uses only one detector to make all three measurements, there is only one calibration necessary. In addition, because it uses only one mechanical axis of rotation it tends to stay in alignment with the sun much better than a two axis tracker, reducing labor required to operate the system.