PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 SPACECRAFT_NAME = MAGELLAN TARGET_NAME = VENUS OBJECT = TEXT PUBLICATION_DATE = 2014-11-26 NOTE = "Notes on the MAGELLAN archive of raw radio tracking data" END_OBJECT = TEXT END MAGELLAN RAW RADIO TRACKING DATA ARCHIVE This file contains errata and user notes for the MAGELLAN raw radio tracking data archive (MGN-V-RSS-1-TRACKING-V1.0). --------------------------------------------------------------------------- One ATDF was lost before the collection was assembled by the PDS GEO Node in 1997. Two corrupted files were not included in the archive, and two files were omitted because they appeared to be duplicates of other files. Coverage (YYYY/DDD) Reason for Omission from Archive ------------------- ---------------------------------- 1990/166-1990/193 Lost before GEO collection in 1997 1991/084-1991/112 Corrupted 1992/034-1992/050 Duplicate 1993/313-1993/313 Duplicate 1994/162-1994/164 Corrupted --------------------------------------------------------------------------- Ordinarily an ODF is derived from an ATDF by editing and compression (integration). The ODFs in this archive were reconstructed from NAVIO files by KJ Lee of the Jet Propulsion Laboratory's Radio Metric Data Conditioning Team. The NAVIO files had been used by Alex Konopliv in deriving the 120x120 and 180x180 gravity models for Venus, but their origin and detailed history is otherwise not known. --------------------------------------------------------------------------- There were two types of errors in the reconstructed ODFs delivered to Stanford. (1) "Format ID" in the Orbit Data File Data (ODFD) records is set to "2", a value that should not have appeared until 1997-04-15. For MAGELLAN the correct value should be "1". This error appears in all ODFD records of all ODFs; it has not been corrected. (2) In ODF/2262011A.ODF approximately the last 6-7 percent of ODFD records and Ramp Group Data (RGD) records (except ramp data from DSS 14, 43, and 63) delivered to Stanford were invalid. The bad records have been removed, and the label file (2262011A.LBL) has been regenerated for the corrected file. --------------------------------------------------------------------------- The ATDF SIS (DOCUMENT/TRK_2_25.TXT) is not up to date on a few points (the PDS label for individual ATDF data files is correct). In TDF1_TABLE and TDF2_TABLE, the spacecraft ID (Item 9) has been expanded to 16 bits, 8 of which were taken from Item 8 (spare). Items 10, 11, and 12 contain the ASCII character string 'TDF'. --------------------------------------------------------------------------- The SFF SIS (DOCUMENT/SFFDR.LBL) for AMD data files was recovered from JPL Archives in PDF. A Microsoft Word file was derived from the PDF by scanning, optical character recognition (OCR), and manual typing. An ASCII version was derived from the Word document. Spelling, grammatical, and other apparent errors in the original have been preserved in the Word and ASCII files. (1) There were at least two changes to the SIS after it was originally released. The changes are documented in an InterOffice Memorandum (IOM) and two Magellan Change Requests (MCRs). The document itself was apparently never updated, but the IOM and MCRs are interleaved with the SIS pages in the PDF; the IOM and MCRs were moved to the front in the Word and ASCII files. (2) There may be other inconsistencies between the archival document and the AMD data files. For example SIS section 2.2 says that data files will never have more than 10 records of 80 bytes each and that the $$EOF marker will denote end-of-file. However, the files in this data set have between 2440 and 43540 records, and $$EOF appears to delimit blocks of variable length records where each block summarizes a single angular desaturation event. --------------------------------------------------------------------------- Ancillary data were added to the archive, but the coverage is not complete. ION data from June-July 1993 are missing, TRO data from February-April 1991 and January-August 1992 are missing, and WEA data from 1991 (all DSN complexes) are missing. --------------------------------------------------------------------------- Shortly before this archive was released for public use, reviewer Pascal Rosenblatt provided a final set of comments and corrections. The archiving team had neither the time nor the expertise to corroborate his findings, so his comments are simply reproduced here for the benefit of others. Dr. Rosen- blatt is actively using these data in his research. 1) The phase of the carrier as recorded in Table TRK-2-25-3 at items 31 and 32 must be interpreted in 'cycles' instead of 'milli-cycles' as wrongly indicated in the TRK-2-25 document. 2) To derive the ramp frequency rate and the frequency at the beginning of the ramp interval, one must modify formulas given in Moyer's book. One must change the numerical coefficients '96' and '32' to '48' and '16', respectively, in formulas 13-1 and 13-2 on page 13-11. The same is true for formulas 13-5 and 13-6 on page 13-12. Note that the formula 13-4 on page 13-11 is not used for the ramp frequency. Only formulas 13-1 and 13-2 work. 3) Then, one must use an algorithm that consists of combining two records read from the TDF files to get one measurement. In this way, I have obtained the same numerical values as in the ODFs provided by Alex [Konopliv]. 4) However, I could not test for range since there was no range in the ODF data base. In addition, it was not possible to get crucial information for the 3-way Doppler data -- the number of the transmitting station. It is not given in the TDF even though 3-way Doppler data exist in the ODF. ---------------------------------------------------------------------------