Embedded system upgrade based on Raspberry Pi computer for a 23/31 GHz dual-channel water vapor radiometer

We present the refurbishment of a 23.8/31.5 GHz tipping radiometer (WVR-III) to characterize atmospheric opacity for astronomical sites. The mid-life upgrade will bring new life to the 20-year-old WVR-III with most control functions now embedded on a Raspberry PI 3B+ (RPi-3B+). The radiometer will be installed alongside the 225 GHz radiometer at the Large Millimeter Telescope site in Mexico and in 2021 it will be taken to the Hartebeesthoek Radio Astronomy Observatory in South Africa. Later, it will be deployed to Mt Gamsberg, Namibia to perform PWV site surveying for potential future radio astronomy telescopes. This paper describes the new control and data acquisition sub-systems that are controlled by the RPi-3B+.The Consejo Nacional de Ciencia y Tecnología (CONACyT-Mexico), the National Research Foundation (South Africa), the Universidad Nacional Autónoma de México (UNAM).https://www.spiedigitallibrary.org/conference-proceedings-of-spieam2021Electrical, Electronic and Computer Engineerin