MESSENGER RSS Radio Occultation Measurements (OCC)

OCC – Radio Occultation Measurements

Instrument: MESSENGER Radio Science Experiment

PDS4 Bundle: urn:nasa:pds:mess_rs_derivedDOI: 10.17189/1518647

For more information about RSS OCC products, see the OCC Product SIS.

The Radio Science Subsystem (RSS) Radio Occultation Measurements (OCC) data product contains results of processing MESSENGER radio occultation data of results from one or more radio occultations. The occultation measurements of Mercury’s radius are based on data acquired using the Radio Science Receiver (RSR) open-loop receiver. The Radio Science System Group (RSSG) extracts the time-dependent RF power as MESSENGER passes behind and past Mercury as viewed from Earth.

The best-performing extraction algorithm is a short-term periodogram using a windowed Fast-Fourier Transform (FFT) with 50% overlap. Normally, the FFT is filtering 4 Hz around the carrier. Other extraction algorithms used are a normal FFT and a software phase-locked loop (PLL). These latter algorithms produced lower signal margins (FFT) or more distortion (PLL) for the lowest signal levels, but sometimes produced the best results for the strongest transmissions. When analyzing with multiple algorithms, the archived value is the one with the lowest uncertainty as measured by the quality of the diffraction fit.

The OCC file is named MESS_RS_OCC_V04.CSV, with its corresponding label file.

In ODE, the OCC file has the following product ID:

mess_rss_occ_v04