Voyager Radio Science investigations at the giant planets utilized instrumentation with elements both on the spacecraft and at the DSN. Much of this was shared equipment, being used for routine telecommunications as well as for Radio Science. The performance and calibration of both the spacecraft and tracking stations directly affected the radio science data accuracy, and they played a major role in determining the quality of the results. The spacecraft part of the radio science instrument is described immediately below; unless noted otherwise, the description applies equally well to both Voyager 1 and Voyager 2 and it applies throughout the Voyager mission. The description of the DSN (ground) part of the instrument follows. Because the DSN was continually changing, that description has been tailored to each Voyager encounter.