It is a Global Gravity measurement at the comet 67P and covers the time 2014-08-29T18:17:00.000 to 2014-08-30T00:54:02.000.
Born Of Osiris A Higher Place Manual RSIUSERMANUAL2004 InFor more information on the investigations see the RSI User Manual RSIUSERMANUAL2004 in the DOCUMENTRSIDOC folder.This is a Global Gravity measurement covering the time 2014-08-29T18:17:00.000 to 2014-08-30T00:54:02.000. This data set was collected during the Rosetta Mission Prelanding Phase (PRL) - on route to comet Churymov-Gerasimenko. For more information about RSI measurements see INST.CAT or the RSI User Manual RSIUSERMANUAL2004. Mission Phase Definition Mission phase abbreviations are defined in CATALOGMISSION.CAT and DOCUMENTESADOCROESTTN3372.PDF. General description of radio science data Closed-loop and Open-loop data: There are in principle two different ways to record radio science data: Open-loop and closed-loop data. The CLOSED-LOOP system used a phase-lock loop in the receiver to track the downlink signal, reporting both amplitude and fre- quency at rates typically of 1-10 times per second. In the OPEN-LOOP system, the signal was simply converted to a baseband frequency range; the entire passband was sampled and recorded for later processing. Typical open-loop sampling rates for ROS were 2000 complex samples per second. CLOSED-LOOP data are efficient for characterizing slowly changing signals; OPEN-LOOP data (because of their much higher volume) are usually used when the signal is very dynamic - such as during an occultation or bistatic radar measurement. The data set includes four primary data types with respect to the two different ground station systems. These systems are on the one hand the ESA ground station in New Norcia, Australia (NNO) and the NASA Deep Space Network (DSN). C. LOSED-LOOP data types: - ESA: Intermediate Frequency Modulation System (IFMS) Closed-Loop (CL) In this data set file names of data recorded at the New Norcia IFMS closed loop system start with the string R32ICL IFMS CL consists of Doppler and Ranging data at selected sample rates. The only exception are occultation data where the sample rate should be 10s to get a good enough vertical resolution of the atmosphere. Thus the IFMS closed loop has three recording systems IFMS 1, IFMS 2 and IFMS 3 The standarddataproductid in the data label specifies on which system the data was recorded. RSI measurements are usually done in TWO-WAY configuration: that is an uplink signal goes up (This is usually X-Band but the uplink signal can also be S-Band) and the ground station receives a dual frequency simultaneous and coherent downlink signal. It receives X-Band downlink if uplink was X-Band and S-Band downlink if uplink was S-Band. IFMS 1 D1 is fixed to a sample rate of 1s IFMS 1 D2 is on fixed to a sample rate of 110s In addition each Doppler recording system has also two Doppler channels which can record simultaneous ly and act as an additional backup system. Therefore for each IFMS system there should be at a given time two Doppler files and two Auto Gain Control files recorded. The file names of these data contain the string D1 or D2 for Doppler and G1 or G2 for Auto Gain control files and they will be on different subfolders within the data directory. Ranging data was nominally recorded on IFMS1. DSN: -Tracking and Navigation File (TNF) The Tracking and Navigation File (TNF) is the primary out put from the DSN closed-loop receiver system. These are large files, accumulating at the rate of approximately 3 megabytes (MB) per hour of antenna operation. The files comprise nearly 20 block types, each designed to carry data of interest to a particular navigation, telecommuni- cations, or science community. The blocks are described by TNFSIS.TXT in the DOCUMENTDSNDOC directory. Fields include: Uplink and downlink antenna numbers Spacecraft number Equipment identifiers, status flags, and calibration values Time tags and frequency bands Transmitted and received phase and frequency Transmitted and received ranging information Noise levels, signal-to-noise ratios, and uncertain- ties -Orbit Data Files (ODF) For many applications the TNF is too cumbersome. The ODF is an edited and partially processed version of the TNF. It is a smaller file, often issued in daily increments of about 0.2 MB. It contains the most important information (range and Doppler) needed by spacecraft navigators and investigators interested in determining gravitational fields of bodies such as Mars.
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