The Grape 1 Legacy Doppler Monitor (fldigi version) is a citizen science instrument developed as part of the HamSCI Personal Space Weather Station (PSWS) project. It is a low-cost, easy-to-assemble system designed to receive, analyze, and record signals from frequency standard stations such as WWV, WWVH, and CHU. Using a low-IF receiver board, a GPS-disciplined oscillator (GPSDO), and a Raspberry Pi running a custom HamSCI fldigi-based image, it measures Doppler frequency shifts caused by ionospheric variations on a 24/7 basis. Data is typically recorded in CSV format. Grape 1 systems have been operational since 2019 and have been used in studies of space weather impacts, including during the 2024 North American total solar eclipse. The Grape 1 is a receive-only device and does not require a ham radio license to operate.

The AB1XB Node 33 is located at 42.479ºN, 71.625ºW. Instrument type is Grape 1 Legacy. There is one antenna at this staton, which is Antenna 1: 30M dipole. It records WWV 10MHz Doppler Shift.