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RECORD_TYPE = FIXED_LENGTH
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OBJECT = TEXT
PUBLICATION_DATE = 2002-04-15
NOTE = "Software Interface Specification for
Mars Global Surveyor Radio Science
Surface Reflection investigation files.
Formatted for display or printing at
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Stanford Center for Radar Astronomy
Mars Global Surveyor Project
Software Interface Specification
Surface Reflection (SRX) Participating Scientist Investigation Files
prepared by
Richard A. Simpson
Center for Radar Astronomy
Stanford University
Stanford, CA 94305-9515
650-723-3525
Version 1.1
15 April 2002
PREFACE
|====================================================================|
| |
| DOCUMENT CHANGE LOG |
| |
|====================================================================|
|REVISION|REVISION| SECTION | REMARKS |
| NUMBER | DATE | AFFECTED | |
|--------+--------+------------+-------------------------------------|
| 1.0 |00/01/14| All |Adapted from RSTP V1.0 SIS |
|--------+--------+------------+-------------------------------------|
| 1.1 |02/04/15| various |Added SRA product |
|--------+--------+------------+-------------------------------------|
| 1.1 |02/04/15|Acrn & Abbrv|Added AGK, HGA, SRA, TCK |
|--------+--------+------------+-------------------------------------|
| 1.1 |02/04/15|Distribution|List matches product distribution |
|--------+--------+------------+-------------------------------------|
| 1.1 |02/04/15| 1.3 |Updated [4]; added [7] |
|====================================================================|
|====================================================================|
| |
| ITEMS TO BE DETERMINED |
| |
|====================================================================|
| REVISION | SECTION | ITEM DESCRIPTION | RESOLUTION |
| NUMBER | AFFECTED | | |
|----------+----------+------------------------+---------------------|
| 1.0 | | none | . |
|====================================================================|
Distribution
MGS/Jet Propulsion Laboratory
B. McGuffie........MS barbara.mcguffie@jpl.nasa.gov
MGS MOLA/Massachusetts Institute of Technology
M. Zuber...........54-518 zuber@tharsis.gsfc.nasa.gov
MGS RST/Centre Nationale d'Etudes Spatiales
G. Balmino........GRGS balmino@pontos.cnes.fr
MGS RST/Goddard Space Flight Center
F.M. Flasar..........Code 693 mike@leprss.gsfc.nasa.gov
F. Lemoine.........Code 926 flemoine@ishtar.gsfc.nasa.gov
D.E. Smith...........Code 920 dsmith@tharsis.gsfc.nasa.gov
MGS RST/Jet Propulsion Laboratory
A. Anabtawi........MS 264-860 aseel@godzilla.jpl.nasa.gov
J. Armstrong.......MS 238-725 john@oberon.jpl.nasa.gov
S.W. Asmar...........MS 264-860 sami.w.asmar@jpl.nasa.gov
A. Konopliv........MS 301-125J ask@krait.jpl.nasa.gov
W.L. Sjogren.........MS 301-150 wls@kamel.jpl.nasa.gov
R. Woo.............MS 238-725 richard.woo@jpl.nasa.gov
D-N Yuan............MS 302-125J dny@krait.jpl.nasa.gov
MGS RST/Stanford University
C-S Han............Packard 325 chinsan@stanford.edu
D.P. Hinson.........Packard 333 hinson@nimbus.stanford.edu
K. Kusza..........Packard 325 kusza@Stanford.edu
R. Simpson........Packard 332 rsimpson@magellan.stanford.edu
J.D. Twicken........Packard 321 joe@neptune.stanford.edu
L. Tyler..........Packard 331 len@nova.stanford.edu
PDS Atmospheres/New Mexico State University
L. Huber..........Dept Astron lhuber@nmsu.edu
PDS Central Node/Jet Propulsion Laboratory
B. Sword..............171-264 betty.sword@jpl.nasa.gov
PDS Geoscience/Washington University
J. Alexopoulos....Dept E&P Sci jim@wuzzy.wustl.edu
E. Guinness.......Dept E&P Sci guinness@wunder.wustl.edu
PDS Planetary Plasma Interations/UCLA
S. Joy............Geology 6707 sjoy@igpp.ucla.edu
Contents
Preface.............................................................ii
Document Change Log...............................................ii
Items to be Determined...........................................iii
Distribution......................................................iv
Contents...........................................................v
Acronyms and Abbreviations.......................................vii
1. General Description...............................................1
1.1. Overview......................................................1
1.2. Scope.........................................................1
1.3. Applicable Documents..........................................1
1.4. System Siting.................................................2
1.4.1. Interface Location and Medium.............................2
1.4.2. Data Sources, Transfer Methods, and Destinations..........2
1.4.3. Generation Method and Frequency...........................2
1.5. Assumptions and Constraints...................................3
1.5.1. Usage Constraints.........................................3
1.5.2. Priority Phasing Constraints..............................3
1.5.3. Explicit and Derived Constraints..........................3
1.5.4. Documentation Conventions.................................3
1.5.4.1. Data Format Descriptions..............................3
1.5.4.2. Time Standards........................................3
1.5.4.3. Coordinate Systems....................................4
1.5.4.4. Limits of This Document...............................4
1.5.4.5. Typographic Conventions...............................4
2. Interface Characteristics.........................................5
2.1. Hardware Characteristics and Limitations......................5
2.1.1. Special Equipment and Device Interfaces...................5
2.1.2. Special Setup Requirements................................5
2.2. Volume and Size...............................................5
2.3. Labeling and Identification...................................5
2.4. Interface Medium Characteristics..............................6
2.5. Failure Protection, Detection, and Recovery Procedures........6
2.6. End-of-File Conventions.......................................6
3. Access............................................................7
3.1. Programs Using the Interface..................................7
3.2. Synchronization Considerations................................7
3.2.1. Timing and Sequencing Considerations......................7
3.2.2. Effective Duration........................................7
3.2.3. Priority Interrupts.......................................7
3.3. Input/Output Protocols, Calling Sequences.....................7
4. Detailed Interface Specifications.................................8
4.1. Structure and Organization Overview...........................8
4.2. Detached PDS Label............................................8
4.2.1. Label Header..............................................8
4.2.2. Label Body...............................................10
4.3. Data Files...................................................10
Appendix A. Example Labels.........................................12
A.1. Example SRA Label............................................12
A.2. Example SRG Label............................................12
A.3. Example SRI Label............................................25
A.4. Example SRT Label............................................26
Figure
4-2. Example SRX Label Header......................................7
Acronyms and Abbreviations
AGK NAIF Antenna Gimbal Kernal
ASCII American Standard Code for Information Interchange
CD Compact Disc
dB Decibel
DSN Deep Space Network
FEA Front End Assembly
GDF GEODYN (Goddard) final ephemeris
GDN GEODYN (Goddard) quick look ephemeris
HGA High-Gain Antenna
IAU International Astronomical Union
IEEE Institute of Electrical and Electronic Engineers
IPN Inner Planet Navigation (Team) ephemeris
JPL Jet Propulsion Laboratory
J2000 IAU Official Time Epoch
K Degrees Kelvin
kB Kilobytes
km Kilometers
MB Megabytes
MGS Mars Global Surveyor
MO Mars Observer
MOLA Mars Orbiting Laser Altimeter
NAIF Navigation and Ancillary Information Facility
NASA National Aeronautics and Space Administration
NAV Navigation Subsystem/Team
ODR Original Data Record
ODS Original Data Stream
OLR Open Loop Receiver
PDS Planetary Data System
POD Precision Orbit Determination
RS Radio Science
RSS Radio Science Subsystem
RST Radio Science Team
RSTP Radio Science Temperature Pressure (profile)
SCET Space Craft Event Time
SIS Software Interface Specification
SOPC Science Operations Planning Computer
SPK Spacecraft and Planetary Kernel (ephemeris)
SRA Surface Reflection Antenna file/table
SRG Surface Reflection Geometry file/table
SRI Surface Reflection Image
SRT Surface Reflection Table
SRX Surface Reflection generic file or file type
TBD To Be Determined
TCK NAIF Spacecraft C-Kernel
TDB Temps Dynamique Barycentrique - IAU Standard Ephemeris
Time
UTC Coordinated Universal Time
WO Write Once
1. General Description
1.1. Overview
This Software Interface Specification (SIS) describes data files
produced during the Surface Reflection investigation conducted by Mars Global
Surveyor (MGS) Radio Science Team (RST) Participating Scientist (PS) Richard
Simpson. The objectives of the investigation include characterization and
interpretation of surface echoes both for their own sake and also to improve
the quality of MGS atmospheric radio occultation results. Echo signal
strength and dispersion can be used to infer dielectric constant, density,
and centimeter-scale roughness of the reflecting surface [1].
Data products include: (1) a Surface Reflection Table (SRT) summarizing
observables (signal strengths, Doppler offsets, etc), (2) a Surface
Reflection Image (SRI) which shows signal amplitude and frequency as a
function of time, (3) a Surface Reflection Geometry (SRG) file which
summarizes the observing geometry for an observation, and (4) a Surface
Reflection Antenna (SRA) file which summarizes spacecraft antenna pointing.
For simplicity, the collection of Surface Reflection files or any single file
or file type may be denoted by SRX in the following description. SRX files
have been designed according to standards of the National Aeronautics and
Space Administration (NASA) Planetary Data System (PDS) [2-3].
SRX files are created at Stanford University. The Surface Reflection
investigation is one of several carried out by the MGS Radio Science
Team [4].
The Mars Global Surveyor Mission is managed by the NASA Jet Propulsion
Laboratory (JPL).
1.2. Scope
The format and content specifications in this SIS apply to all phases
of the Mars Global Surveyor Mission for which SRX files are produced.
1.3. Applicable Documents
[1] Simpson, R.A., Spacecraft Studies of Planetary Surfaces Using Bistatic
Radar, IEEE Transactions on Geoscience and Remote Sensing, 31, 465-482, 1993.
[2] Planetary Science Data Dictionary, JPL D-7116, Rev. D, 15 July 1996.
[3] Planetary Data System Standards Reference, JPL D-7669, part 2,
24 July 1995.
[4] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R.A.
Simpson, S.W. Asmar, P. Priest, and J.D. Twicken, Radio Science Observations
with Mars Global Surveyor: Orbit Insertion Through One Mars Year in Mapping,
J. Geophys. Res., 102, 23327-23348, 2001.
[5] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo,
J.W. Armstrong, F.M. Flasar, R.A. Simpson, and P. Priest, MGS: Raw Radio
Science Data from Orbit Insertion, R.A. Simpson, editor,
USA_NASA_JPL_MORS_0201 - USA_NASA_JPL_MORS_0359, 1997-1999.
[6] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo,
J.W. Armstrong, F.M. Flasar, R.A. Simpson, and P. Priest, MGS: Raw Radio
Science Data from Mapping, R.A. Simpson, editor, USA_NASA_JPL_MORS_0401 -
USA_NASA_JPL_MORS_0584, 1999-2001.
[7] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo,
J.W. Armstrong, F.M. Flasar, and R.A. Simpson, Mars Global Surveyor Raw Data
Set - EXT V1.0, R.A. Simpson, editor, USA_NASA_JPL_MORS_0601 - , 2001- .
[8] Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo,
J.W. Armstrong, F.M. Flasar, R.A. Simpson, and P. Priest, MGS RST Science
Data Products, R.A. Simpson, editor, USA_NASA_JPL_MORS_1001 -, 1999-.
[9] RSC-11-11, DSN Radio Science System Original Data Record (ODR) and
Original Data Stream (ODS), DSN System requirements - Detailed Interface
Design (Document 820-13; Rev. A), 1992.
[10] Simpson, R.A., Software Interface Specification: Radio Science Digital
Map (RSDMAP) Products, Mars Global Surveyor Project Radio Science Team, 9
March 1999.
[11] MO 642-321, Mars Observer Planetary Constants and Models, JPL D-3444,
November 1990.
1.4. System Siting
1.4.1. Interface Location and Medium
SRX files are created on the Stanford MGS RST processing system which
consists of Sun Ultra-1, Sun Ultra-2, Sun Ultra-5, and other computers and
peripherals.
1.4.2. Data Sources, Transfer Methods, and Destinations
SRX files are derived from files in the MGS RST raw data archive
[5-7]. They are stored on magnetic disk, then written to compact-disk (CD)
write-once (WO) volumes as part of the MGS RST Science Data Products (SDP)
archive [8]. The MGS RST SDP archive is delivered to the Planetary Data
System (PDS) for distribution to potential users in the planetary science
community.
1.4.3. Generation Method and Frequency
SRI files are created from Original Data Records (ODRs) [9]. ODR
samples are processed coherently to yield power spectra. The typical SRI is
300 consecutive 512-point power spectra stored as a two-dimensional array in
Radio Science Digital Map format [10]. The image generally shows the MGS X-
band carrier signal and any surface echoes that may be present.
Each SRT file provides quantitative information in tabular form to
accompany an SRI file. Estimates of MGS carrier power and frequency are
obtained by searching each spectrum for the maximum signal. The surface echo
is found using a guided search algorithm for anomalously large signals to the
side of the carrier.
SRG files give summaries of observing geometry around events of
interest. Calculations are based on ephemerides provided by the MGS
Navigation (NAV) Team and others. Although an immediate application is to
interpretation of SRI and SRT files, the SRG is not limited to that
application.
SRA files give summaries of spacecraft high-gain antenna (HGA) pointing
around events of interest. Absolute pointing is derived from spacecraft
attitude (TCK) and antenna gimbal (AGK) files. Offsets from the Earth-MHS
line are found from comparison of absolute pointing with data in the SRG file.
SRI and SRT files are generated (as resources allow) when surface echoes
have been detected or are expected in ODRs. SRG files are generated as
needed. SRA files are generated when the input data become available. If an
occultation was recorded at two or more ground antennas, there may be multiple
SRI and SRT files; but there will generally be only one SRG file and no more
than one SRA file. SRA files will not be produced if SRG, TCK, or AGK files
could not be found.
1.5. Assumptions and Constraints
1.5.1. Usage Constraints
None.
1.5.2. Priority Phasing Constraints
None.
1.5.3. Explicit and Derived Constraints
None.
1.5.4. Documentation Conventions
1.5.4.1. Data Format Descriptions
The reference data unit is the byte. Data may be stored in fields with
various sizes and formats, viz. one-, two-, and four-byte binary integers,
four- and eight-byte binary floating-point numbers, and character strings.
Data are identified throughout this document as
char 8 bits character
uchar 8 bits integer
short 16 bits integer
long 32 bits integer
float 32 bits floating point (sign, exponent, and
mantissa)
double 64 bits floating point (sign, exponent, and
mantissa)
u (prefix) unsigned (as with ulong for
unsigned 32-bit integer)
other special data structures such as
time, date, etc. which are
described within this document
If a field is described as containing n bytes of ASCII character
string data, this implies that the leftmost (lowest numbered) byte contains
the first character, the next lowest byte contains the second character, and
so forth.
An array of n elements is written as array[n]; the first element is
array[0], and the last is array[n-1]. Array[n][m] describes an n x m
element array, with first element array[0][0], second element array[0][1],
and so forth.
1.5.4.2. Time Standards
SRX calculations use the January 1.5, 2000 epoch as the standard time.
Within the data files, all times are reported in Universal Coordinated Time
(UTC) as strings of up to 24 ASCII characters. The time format is "YYYY-MM-
DDThh:mm:ss.fff", where "-", "T", ":", and "." are fixed delimiters; "YYYY" is
the year "19nn" or "20nn"; "MM" is a two-digit month of year; "DD" is a two-
digit day of month; "T" separates the date and time segments of the string;
"hh" is hour of day; "mm" is the minutes of hour (00-59); "ss" is the seconds
of hour (00-59); and "fff" is in milliseconds. The decimal point and "fff"
are optional. Optional suffix "Z" explicitly indicates use of the UTC
reference.
The date format is "YYYY-MM-DD", where the components are defined as
above. A three-digit day-of-year "DDD" may be substituted for "MM-DD" in
either the time or date format.
1.5.4.3. Coordinate Systems
SRX files use Areocentric J2000 inertial coordinates and the Areocentric
fixed body coordinate system [11].
1.5.4.4. Limits of This Document
This document applies only to SRX products.
1.5.4.5. Typographic Conventions
This document has been formatted for simple electronic file transfer and
display. Line lengths are limited to 80 ASCII characters, including line
delimiters. No special fonts or structures are included within the file.
Constant width characters are assumed for display.
2. Interface Characteristics
2.1. Hardware Characteristics and Limitations
2.1.1. Special Equipment and Device Interfaces
SRX files are created on the Stanford MGS Science Operations Planning
Computer (SOPC) using IEEE formats and are stored in electronic form on
magnetic disk and CD-WO media
2.1.2. Special Setup Requirements
None.
2.2. Volume and Size
SRX products typically consist of one SRI, SRT, SRG, and SRA file for
each event studied. Nominal file sizes are 300, 40, and 400 kB, respectively,
with associated labels requiring 5, 15, and 60 kB. Total volume for a single
event (e.g., one occultation) would be approximately 820 kB.
2.3. Labeling and Identification
Each file has a name which describes its contents. The name includes the
following structure which uniquely identifies it among Mars Global Surveyor
Radio Science products:
ydddHmmC.SRx
where
y is the least significant digit of the year
ddd is the day of year
H is a one character representation of the hour on which
the file begins (A = 00, B = 01, ... X = 23)
mm is the minute on which the file begins (see note below for
convention when two acquisition systems began at the same
minute; applies only to SRI and SRT files)
C is a single character denoting the version of the file
(first version is "A", second is "B", etc.)
"SR" identifies the file as containing a Radio Science
Surface Reflection data file,
"x" indicates the specific product
"A" summary antenna pointing table
"G" summary geometry table
"I" image file
"T" radio observables (table)
Note: Some events may be captured by more than one ground station
with recording beginning at the same time. In those cases the
least significant digit of mm will be modified as follows
(applies only to SRI and SRT files):
Least Significant Digit of "mm" for Coincident Files
First Data File Second Data File Third Data File
--------------- ---------------- ---------------
0 A K
1 B L
2 C M
3 D N
4 E O
5 F P
6 G Q
7 H R
8 I S
9 J T
2.4. Interface Medium Characteristics
SRX products are electronic files. CD-WO volumes conform to standards
of the Planetary Data System [3].
2.5. Failure Protection, Detection, and Recovery Procedures
None.
2.6. End-of-File Conventions
End of file labeling complies with standards for CD-WO media.
3. Access
3.1. Programs Using the Interface
Data contained in SRX files will be accessed by programs at the home
institutions of Mars Global Surveyor and other investigators. Those programs
cannot be identified here.
3.2. Synchronization Considerations
3.2.1. Timing and Sequencing Considerations
N/A
3.2.2. Effective Duration
N/A
3.2.3. Priority Interrupts
None.
3.3. Input/Output Protocols, Calling Sequences
None.
4. Detailed Interface Specifications
4.1. Structure and Organization Overview
The SRA, SRG, SRI, and SRT files (collectively known as SRX files) are
generated by Radio Science data reduction and analysis software at Stanford
University. Each SRX file is accompanied by a detached PDS label.
4.2. Detached PDS Label
The detached PDS label has two parts -- a header and body. The header
contains information about the origin of the file and its general
characteristics such as record type and size. The body is a complete bit-
level definition of the SRX file; it includes object definitions for each
component of the SRX file.
Each detached PDS label is constructed of ASCII records; each record
contains exactly 80 characters. The last two characters in each record are
the carriage-return (ASCII 13) and line-feed (ASCII 10) characters.
4.2.1 Label Header
The structure of the label file header is illustrated in Figure 4-2.
Keyword definitions are given below. Not all keywords appear in all labels,
nor will they always be in the same order. Examples of complete label files
are given in Appendix A.
|====================================================================|
| |
| Figure 4-2. Example SRX Label Header |
| |
|====================================================================|
| |
| PDS_VERSION_ID = PDS3 |
| RECORD_TYPE = FIXED_LENGTH |
| RECORD_BYTES = 100 |
| FILE_RECORDS = nnn |
| ^xxxx = ("ydddHmmC.SRx",1) |
| ^xxxx = ("ydddHmmC.SRx",n) |
| ... |
| INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR" |
| TARGET_NAME = "MARS" |
| INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM" |
| DATA_SET_ID = "MGS-M-RSS-5-SDP-Vn.m" |
| PRODUCT_ID = "ydddHmmC.SRx" |
| ORIGINAL_PRODUCT_ID = "cccccccccc" |
| PRODUCT_RELEASE_DATE = YYYY-MM-DD |
| DESCRIPTION = "cccccccccccccccccc" |
| START_TIME = YYYY-MM-DDThh:mm:ss |
| STOP_TIME = YYYY-MM-DDThh:mm:ss |
| SOFTWARE_NAME = "ccccccc;Vn.m" |
| PRODUCT_CREATION_TIME = YYYY-MM-DDThh:mm:ss |
| PRODUCER_ID = "MGS RST" |
| |
|====================================================================|
PDS_VERSION_ID = The version of the Planetary Data System for which
these data have been prepared (set to PDS 3 by
agreement between the Mars Global Surveyor and PDS).
RECORD_TYPE = The type of record. Set to "FIXED_LENGTH" to
indicate that all records have the same length.
RECORD_BYTES = The number of bytes per (fixed-length) record.
Varies among products, and may vary as the product
evolves. Initially set to "80" for the SRA, "688"
for the SRG, "1024" for the SRI, and "50" for the
SRT.
FILE_RECORDS = The number of records in the SRX file; instance
dependent.
^xxxx = File name and record number at which a data object
begins; repeated for each data object. The SRA
contains two data objects (HGA_POINTING_HDR_TABLE
and HGA_POINTING_TABLE). The SRG
contains two data objects (BSR_GEOM_HDR_TABLE and
BSR_GEOM_TABLE). The SRT contains two data objects
(SURF_HDR_TABLE) and (SURF_TABLE). The SRI contains
one data object (IMAGE); in this case, the
parentheses, comma, and record number are omitted.
The file naming convention is defined in
Section 2.3. Record number starts at 1 and is
incremented once for each RECORD_BYTES.
INSTRUMENT_HOST_NAME = Name of the spacecraft; set to "MARS GLOBAL
SURVEYOR".
TARGET_NAME = A character string which identifies the target body.
Set to "MARS".
INSTRUMENT_NAME = Name of the instrument; set to "RADIO SCIENCE
SUBSYSTEM".
DATA_SET_ID = Identifier for the data set of which this SRX
product is a member. Set to "MGS-M-RSS-5-SDP-Vn.m",
where "Vn.m" indicates the version number of the
data set.
PRODUCT_ID = A unique identifier for the product within the MGS
RST collection of data sets. The naming convention
is defined in Section 2.3.
ORIGINAL_PRODUCT_ID = The name of the file upon which this product was
primarily based. This keyword is used only for
SRG products, where it specifies the source SPK
file using the MGS RST file naming convention
ydddeeeC.EXT. In the name y is the one-digit start
year, ddd is the 3-digit start day-of-year, eee is
the 3-digit stop day-of-year, C is the version
('A' is first, 'B' second, etc.), and EXT denotes
one of several SPK sources (SPK if from MGS NAV,
GDN if a quick-look solution from the MOLA POD Team,
GDF if a final MOLA POD solution, and IPN if from
the JPL Inner Planet Navigation Group).
PRODUCT_RELEASE_DATE = A largely fictitious date on which the product may
be released by the Mars Global Surveyor Project to
the Planetary Data System; entered in the format
"YYYY-MM-DD", where components are defined in
Section 1.5.4.2. Optional
DESCRIPTION = A short description of the SRX product.
START_TIME = The Earth Receive Time at which the first real (or
virtual, in the case of SRG files) radio sample was
acquired expressed in the format
YYYY-MM-DDThh:mm:ss
where the components are defined in Section 1.5.4.2.
STOP_TIME = The Earth Receive Time at which the last sample was
acquired expressed in the format
YYYY-MM-DDThh:mm:ss
where the components are defined in Section 1.5.4.2.
SOFTWARE_NAME = The name and version number of the program creating
the SRX file; expressed as a character string in the
format "PROGRAM_NAME;n.mm" where "PROGRAM_NAME" is
the name of the software and "n.mm" is the version
number. Optional.
PRODUCT_CREATION_TIME = The time at which the SRX file was created;
expressed in the format
YYYY-MM-DDThh:mm:ss
where the components are defined in Section 1.5.4.2.
PRODUCER_ID = The entity responsible for creation of the SRX
product; set to "MGS RST". Optional.
4.2.2 Label Body
The body of the PDS label completely defines both the format and the
content of the associated SRX file. It is written as one or two OBJECT
definitions -- one for the header (if any) and one for the data. Examples of
complete labels are given in Appendix A. Since the format and content of the
SRX files may evolve over the course of the MGS mission, users should always
refer to the accompanying label for current specifications of the SRX file.
4.3. Data Files
The SRA file contains summary lines for the high-gain antenna pointing
at fixed time steps (typically 1, 10, or 100 s). It comprises two PDS TABLE
objects -- one containing "fingerprint" information and assumed constants for
the calculation and the other containing results. The structure and content
of each SRA file is defined by the accompanying detached PDS label (see
Section 4.2 and Appendix A).
The SRG file contains summary lines for the observational geometry at
fixed time steps (typically 1, 10, or 100 s). It comprises two PDS TABLE
objects -- one containing "fingerprint" information and assumed constants for
the calculation and the other containing results. The structure and content
of each SRG file is defined by the accompanying detached PDS label (see
Section 4.2 and Appendix A).
The SRI file is a two-dimensional image in RSDMAP format [10]. The
structure and content of each SRI file is defined by the accompanying detached
PDS label (see Section 4.2 and Appendix A).
The SRT data file contains estimates of the power and frequency of the
MGS X-band carrier and surface echo. It comprises two PDS TABLE objects --
one containing "fingerprint" information and assumed constants for the
calculations and the other containing the measurements themselves. The
structure and content of each SRT file is defined by the accompanying detached
PDS label (see Section 4.2 and Appendix A).
Note that the format and content of SRX files may evolve over the course
of the MGS mission; users should always refer to the accompanying PDS label
for current format and content specifications.
A. Example Labels
A.1 Example SRA Label
PDS_VERSION_ID = PDS3
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 80
FILE_RECORDS = 602
^HGA_POINTING_HDR_TABLE = ("9127M28A.SRA",1)
^HGA_POINTING_TABLE = ("9127M28A.SRA",3)
INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR"
TARGET_NAME = "MARS"
INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM"
DATA_SET_ID = "MGS-M-RSS-5-SDP-V1.0"
PRODUCT_ID = "9127M28A.SRA"
START_TIME = 1999-05-07T12:28:00
STOP_TIME = 1999-05-07T12:37:59
PRODUCT_CREATION_TIME = 2002-03-29T21:09:40
DESCRIPTION = "This file summarizes high-gain
antenna (HGA) pointing for Mars Global Surveyor (MGS) bistatic
radar (BSR) observations. For highly oblique BSR, the results
may also apply to the accompanying atmospheric occultation.
The file gives the HGA unit vector and offset angles from
the desired pointing direction as a function of time.
The file comprises two tables. The first table is a single row
which identifies the calculation (fingerprints). The second
table (with many rows) is the HGA summary itself.
File names are of the form ydddHmmC.SRA where y is the one-digit
year, ddd is the 3-digit day-of-year, H is a letter denoting the
hour (A=00, B=01, ..., X=23), and mm is the 2-digit minute of the
first data in the file. C indicates version of the file; C='A'
is the first version, 'B' is the second version, etc. ydddHmm
With regard to the file naming convention, ydddHmm
in these files is intended to be SIMILAR to ydddHmm in TPS and
TPH occultation file names and in SRT and SRI surface
scattering file names. However, because SRA files are produced
independently, this correspondence cannot be guaranteed. Further,
mm in the other files can sometimes include a letter -- if data
were collected simultaneously at two antennas; and the version
indicators (C) may be entirely different.
Reconstruction of the HGA pointing was carried out by Joe Twicken
using the NAIF Toolkit and kernels. The SRA file was produced by
Dick Simpson of the MGS Radio Science Team (RST) as part of his
Participating Scientist investigation."
OBJECT = HGA_POINTING_HDR_TABLE
NAME = "HGA POINTING HEADER"
INTERCHANGE_FORMAT = ASCII
ROWS = 1
COLUMNS = 14
ROW_BYTES = 152
ROW_SUFFIX_BYTES = 8
DESCRIPTION = "Table contains identifying information and
summary data about the HGA pointing for one
BSR event. Table contains a single row of
14 columns giving date, orbit number, sense
of the occultation, file names used in
constructing the Earth-Mars-MGS geometry,
file names used in reconstructing the HGA
pointing, occultation time, and average
angle offsets from the desired pointing
direction. Columns are delimited by commas;
total space occupied by data columns and
column delimiters is 150 bytes. The row is
padded with 8 ASCII blanks. An ASCII
carriage-return and line-feed occupy byte
positions 159 and 160."
OBJECT = COLUMN
COLUMN_NUMBER = 1
NAME = "DATE"
DATA_TYPE = DATE
START_BYTE = 1
BYTES = 10
FORMAT = "A10"
DESCRIPTION = "Date on which the observations began, given
in a YYYY-MM-DD format where YYYY is the
4-digit year, MM is the 2-digit month, and
DD is the 2-digit day."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 2
NAME = "ORBIT NUMBER"
DATA_TYPE = ASCII_INTEGER
START_BYTE = 12
BYTES = 5
FORMAT = "I5"
DESCRIPTION = "Orbit number during which the data were
collected."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 3
NAME = "OCCULTATION SENSE"
DATA_TYPE = CHARACTER
START_BYTE = 19
BYTES = 1
FORMAT = "A1"
DESCRIPTION = "Sense of the occultation, if any. Possible
values include: E for egress, I for ingress,
B for both (grazing occultation), and X
for undefined (for example, data acquired
when there was no occultation, such as
during a specular point experiment)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 4
NAME = "DSS"
DATA_TYPE = ASCII_INTEGER
START_BYTE = 22
BYTES = 2
FORMAT = "I2"
DESCRIPTION = "DSN antenna through which the data were
collected."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 5
NAME = "SRT FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 26
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of SRT file in which reduced surface
echo data have been tabulated. Left blank
if there is no associated SRT file."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 6
NAME = "SRG FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 41
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of SRG file in which geometry data
for the experiment have been tabulated.
The SRG file is the source of the vectors
defining relative positions of Earth,
Mars, and spacecraft."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 7
NAME = "SOURCE SPK1 FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 56
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of SPK file used to generate the
SRG file."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 8
NAME = "SOURCE SPK2 FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 71
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of SPK file used in reconstruction
of the HGA pointing."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 9
NAME = "TCK FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 86
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of TCK file used in reconstruction
of the HGA pointing. TCK file defines
the attitude of the spacecraft body."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 10
NAME = "AGK FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 101
BYTES = 12
FORMAT = "A12"
DESCRIPTION = "Name of AGK file used in reconstruction
of the HGA pointing. AGK file defines
the azimuth and elevation gimbal angles
for the HGA."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 11
NAME = "TOCC"
DATA_TYPE = ASCII_REAL
START_BYTE = 115
BYTES = 12
FORMAT = "F12.6"
UNIT = "SECOND"
DESCRIPTION = "Time at which occultation ray was tangent
to the surface of Mars. Derived from the
time at which the carrier was roughly 25%
of its free-space intensity, adjusted for
light-time to Earth, and stored in the
SRT file."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 12
NAME = "AVG ANGY"
DATA_TYPE = ASCII_REAL
START_BYTE = 128
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Average value of ANGY during 20 seconds
after egress or 20 seconds before ingress.
See below for definition of ANGY."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 13
NAME = "AVG ANGX"
DATA_TYPE = ASCII_REAL
START_BYTE = 136
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Average value of ANGX during 20 seconds
after egress or 20 seconds before ingress.
See below for definition of ANGX."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 14
NAME = "AVG ANGZ"
DATA_TYPE = ASCII_REAL
START_BYTE = 144
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Average value of ANGZ during 20 seconds
after egress or 20 seconds before ingress.
See below for definition of ANGZ."
END_OBJECT = COLUMN
END_OBJECT = HGA_POINTING_HDR_TABLE
OBJECT = HGA_POINTING_TABLE
NAME = "HGA POINTING"
INTERCHANGE_FORMAT = ASCII
ROWS = 600
COLUMNS = 6
ROW_BYTES = 80
DESCRIPTION = "Table contains HGA unit vector and offset
angles from desired HGA pointing direction versus time.
The tables are constructed with Earth Receive Time (ERT, or
TRX) in the first column, the corresponding transmit time
(TTX) in the second column, the three-element reconstructed
pointing vector (HGA) in the third column, and the offset
angles (ANGY, ANGX, and ANGZ) in columns 4-6.
For computing the offset angles we define a local coordinate
system as follows. DSD is the SRG vector from the spacecraft
at transmit to the Earth at receive. DOS is the SRG vector
from the center of Mars to the spacecraft at transmit time.
DOP is the SRG vector from the center of Mars to the specular
point at transmit time. For a transient (occultation) echo
event
+Y axis is in the direction of DSD
+Z axis is in the direction of +Y crossed with DOS
+X axis is in the direction of +Y crossed with +Z
For a specular point experiment, +Y is in the direction
DOP-DOS; +X and +Z are defined as above. In either case
ANGY is the angle between +Y and HGA
ANGX is the projection of ANGY onto the XY plane
with positive values toward +X
ANGZ is the projection of ANGY onto the YZ plane
with positive values toward +Z
This is an ASCII table. Columns and items are delimited by
commas (vectors are considered to be single columns comprising
three 'items'). Data and delimiters occupy the first 78 bytes
of each row; rows are delimited by an ASCII carriage-return
line-feed pair in byte positions 79 and 80."
OBJECT = COLUMN
COLUMN_NUMBER = 1
NAME = "TRX"
DATA_TYPE = ASCII_REAL
START_BYTE = 1
BYTES = 10
FORMAT = "F10.3"
UNIT = SECOND
DESCRIPTION = "Earth received time (ERT) for which the
the antenna pointing calculations were made.
TRX is the time (UTC) when an Earth-based
observer would see this geometry. Given
in seconds from midnight. For date, see
Column 1 in the HGA_POINTING_HDR_TABLE."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 2
NAME = "TTX"
DATA_TYPE = ASCII_REAL
START_BYTE = 12
BYTES = 10
FORMAT = "F10.3"
UNIT = SECOND
DESCRIPTION = "Transmit time corresponding to TRX. The
one-way light time for a photon traveling
directly from the spacecraft to the DSN
station has been subtracted from TRX."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 3
NAME = "HGA"
DATA_TYPE = ASCII_REAL
START_BYTE = 23
BYTES = 29
ITEMS = 3
ITEM_BYTES = 10
ITEM_OFFSET = 11
FORMAT = "F10.6"
UNIT = "N/A"
DESCRIPTION = "HGA unit vector in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 4
NAME = "ANGY"
DATA_TYPE = ASCII_REAL
START_BYTE = 56
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Angle between desired direction and
reconstructed HGA unit vector."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 5
NAME = "ANGX"
DATA_TYPE = ASCII_REAL
START_BYTE = 64
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Component of ANGY toward the surface."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 6
NAME = "ANGZ"
DATA_TYPE = ASCII_REAL
START_BYTE = 72
BYTES = 7
FORMAT = "F7.3"
UNIT = "DEGREE"
DESCRIPTION = "Component of ANGY along the limb."
END_OBJECT = COLUMN
END_OBJECT = HGA_POINTING_TABLE
END
A.2 Example SRG Label
PDS_VERSION_ID = PDS3
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 688
FILE_RECORDS = 722
^BSR_GEOM_HDR_TABLE = ("0055A00A.SRG",1)
^BSR_GEOM_TABLE = ("0055A00A.SRG",2)
INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR"
TARGET_NAME = "MARS"
INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM"
DATA_SET_ID = "MGS-M-RSS-5-SDP-V1.0"
PRODUCT_ID = "0055A00A.SRG"
START_TIME = 2000-02-24T00:00:00
STOP_TIME = 2000-02-24T02:00:00
ORIGINAL_PRODUCT_ID = "0031215A.SPK"
PRODUCT_CREATION_TIME = 2000-01-14T02:52:23
DESCRIPTION = "This file summarizes observing
geometry for Mars Global Surveyor (MGS) bistatic radar (BSR)
observations. The results apply to both atmospheric occultations
and surface scattering, but more parameters of interest for
surface studies have been included. START_TIME and STOP_TIME
(above) are Earth Receive Time (ERT).
The file comprises two tables. The first table is a single row
which identifies the calculation (fingerprints). The second
table (with many rows) is the geometry summary itself.
File names are of the form ydddHmmC.SRG where y is the one-digit
year, ddd is the 3-digit day-of-year, H is a letter denoting the
hour (A=00, B=01, ..., X=23), and mm is the 2-digit minute of the
first data in the file. C indicates version of the file; C='A'
is the first version, 'B' is the second version, etc. ydddHmm
in these files is intended to be SIMILAR to ydddHmm in TPS and
TPH occultation file names and in SRT and SRI surface
scattering file names. Because SRG files are produced
independently, this correspondence cannot be guaranteed. Further,
mm in the other files can sometimes include a letter -- if data
were collected simultaneously at two antennas; and the version
indicators (C) may be entirely different.
This file was produced by Dick Simpson of the MGS Radio Science
Team (RST) as part of his Participating Scientist investigation."
OBJECT = BSR_GEOM_HDR_TABLE
NAME = "BSR GEOMETRY HEADER"
INTERCHANGE_FORMAT = ASCII
ROWS = 1
COLUMNS = 7
ROW_BYTES = 77
ROW_SUFFIX_BYTES = 611
DESCRIPTION = "Table contains identifying information and
constants for use with the geometry in the
next table. Table contains a single row of
7 columns giving DSN antenna number, input
SPK file name, assumed planet radius and
speed of light, latitude and longitude of
a user-specified target point, and time
spacing of rows in next table. Columns are
delimited by commas; total space occupied by
data columns and delimiters is 75 bytes.
The row is padded with 611 ASCII blanks.
An ASCII carriage-return and line-feed
occupy byte positions 687 and 688."
OBJECT = COLUMN
COLUMN_NUMBER = 1
NAME = "DSS"
DATA_TYPE = ASCII_INTEGER
START_BYTE = 1
BYTES = 2
FORMAT = "I2"
DESCRIPTION = "Deep Space Network antenna number."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 2
NAME = "SPK FILE NAME"
DATA_TYPE = CHARACTER
START_BYTE = 5
BYTES = 12
DESCRIPTION = "File name of the SPK file used to generate
the geometry data in the BSR GEOMETRY table.
File name is of the form ydddeeeC.EXT where
y is the least significant digit in the
year, ddd is the start day-of-year for the
SPK data, eee is end day-of-year for the
SPK data, C denotes the version of the SPK
file ('A' is first, 'B' is second, etc.),
and EXT is one of several possible
extensions:
SPK standard MGS NAV Team SPK file
GDN quick-look Goddard reconstruction
GDF final Goddard reconstruction
IPN reconstruction by JPL IPNG
The ydddeeeC.EXT naming convention was
adopted by the MGS RST to simplify tracking
of SPK files; the ORIGINAL_PRODUCT_ID can
be found in the detached label for the SPK
file."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 3
NAME = "RP"
DATA_TYPE = ASCII_REAL
START_BYTE = 19
BYTES = 12
FORMAT = "F12.3"
UNIT = "METER"
DESCRIPTION = "Assumed radius for spherical planet. Note
that partial derivatives with respect to
Rp are given for many important quantities,
so the assumption of a single radius is
not as restrictive as it might first seem."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 4
NAME = "VLITE"
DATA_TYPE = ASCII_REAL
START_BYTE = 32
BYTES = 14
FORMAT = "F14.3"
UNIT = "METER PER SECOND"
DESCRIPTION = "Assumed speed of light in vacuum."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 5
NAME = "TLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 47
BYTES = 9
FORMAT = "F9.4"
UNIT = "DEGREE"
DESCRIPTION = "Planetocentric latitude of user-specified
target point. This point may or may not
be meaningful for a given application. It
was included to facilitate planning and
analysis of spotlight mode surface
scattering experiments."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 6
NAME = "TLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 57
BYTES = 9
FORMAT = "F9.4"
UNIT = "DEGREE"
DESCRIPTION = "Planetocentric east longitude of
user-specified target point. This point
may or may not be meaningful for a given
application. It was included to
facilitate planning and analysis of
spotlight mode surface scattering
experiments."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 7
NAME = "DT"
DATA_TYPE = ASCII_REAL
START_BYTE = 67
BYTES = 9
FORMAT = "F9.3"
UNIT = "SECOND"
DESCRIPTION = "Time spacing between rows in next table."
END_OBJECT = COLUMN
END_OBJECT = BSR_GEOM_HDR_TABLE
OBJECT = BSR_GEOM_TABLE
NAME = "BSR GEOMETRY"
INTERCHANGE_FORMAT = ASCII
ROWS = 721
COLUMNS = 34
ROW_BYTES = 688
DESCRIPTION = "Table values allow reconstruction of bistatic
observing geometry. The 34 columns give Earth receive time;
transmit time; Mars fixed-body x, y, and z unit vectors;
positions of spacecraft, DSN receiver, and various surface points
(specular point, backscatter point, closest approach of
occultation ray, and a user-specified target point); incidence,
scattering, and bistatic angles at these points; and
sensitivities of several quantities to changes in planet radius.
The user-specified target point is given in areocentric
latitude and longitude. Depending on the application, it may
or may not be meaningful. For MGS, one such point might be
the Mars Polar Lander target site.
The backscatter point is where the line connecting the DSN
receiver and the spacecraft intersects the planetary surface.
At the backscatter point, the bistatic angle is zero. The
backscatter point is only defined when the spacecraft appears
silhouetted against the planet disk when viewed from the
receiver on Earth (that is, when the planet surface appears
to be behind the spacecraft).
The raypath closest approach point is where the line connecting
the receiver and spacecraft is closest to the planetary surface.
This is the same construction as for the backscatter point; but
the raypath closest approach point is defined only when the
spacecraft is NOT silhouetted against the disk AND when the
receiver-to-spacecraft distance is greater than the distance
between the planet center of mass and the receiver.
The specular point is where angle of incidence equals angle
of reflection and where the incidence plane and the scattering
plane are the same. When the spacecraft is in occultation,
the specular point is not defined.
Vectors are given in inertial J2000 coordinates. Latitudes
and longitudes are given in areocentric fixed body (rotating)
coordinates. Values at Mars are given at transmit time;
values at Earth are given at ERT. Mixed quantities (e.g.,
vector from spacecraft to DSN station) are combinations.
Mars is assumed to be a sphere of radius (3397+3397+3375)/3
kilometers. Speed of light is assumed to be 299792458 m/s.
This is an ASCII table. Columns and items are delimited by
commas (vectors are considered to be single columns comprising
three 'items'). Data and delimiters occupy the first 686 bytes
of each row; rows are delimited by an ASCII carriage-return
line-feed pair in byte positions 687 and 688."
OBJECT = COLUMN
COLUMN_NUMBER = 1
NAME = "TRX"
DATA_TYPE = ASCII_INTEGER
START_BYTE = 1
BYTES = 5
FORMAT = "I5"
UNIT = SECOND
DESCRIPTION = "Earth received time (UTC) for which the
geometrical calculations were made."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 2
NAME = "TTX"
DATA_TYPE = ASCII_REAL
START_BYTE = 7
BYTES = 12
FORMAT = "F12.6"
UNIT = SECOND
DESCRIPTION = "Transmit time corresponding to TRX. The
one-way light time for a photon traveling
directly from the spacecraft to the DSN
station has been subtracted from TRX."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 3
NAME = "NPOLE"
DATA_TYPE = ASCII_REAL
START_BYTE = 20
BYTES = 29
ITEMS = 3
ITEM_BYTES = 9
ITEM_OFFSET = 10
FORMAT = "F9.6"
UNIT = "N/A"
DESCRIPTION = "North Pole unit vector in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 4
NAME = "FBODX"
DATA_TYPE = ASCII_REAL
START_BYTE = 50
BYTES = 29
ITEMS = 3
ITEM_BYTES = 9
ITEM_OFFSET = 10
FORMAT = "F9.6"
UNIT = "N/A"
DESCRIPTION = "Fixed body Mars x-axis unit vector in J2000
coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 5
NAME = "FBODY"
DATA_TYPE = ASCII_REAL
START_BYTE = 80
BYTES = 29
ITEMS = 3
ITEM_BYTES = 9
ITEM_OFFSET = 10
FORMAT = "F9.6"
UNIT = "N/A"
DESCRIPTION = "Fixed body Mars y-axis unit vector in J2000
coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 6
NAME = "DOD"
DATA_TYPE = ASCII_REAL
START_BYTE = 110
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Center of Mars to DSN vector at TRX in
J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 7
NAME = "DOS"
DATA_TYPE = ASCII_REAL
START_BYTE = 152
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Center of Mars to spacecraft vector at
TTX in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 8
NAME = "DSD"
DATA_TYPE = ASCII_REAL
START_BYTE = 194
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Spacecraft (TTX) to DSN (TRX) vector in
J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 9
NAME = "DOT"
DATA_TYPE = ASCII_REAL
START_BYTE = 236
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Vector from center of Mars to user-specified
surface point in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 10
NAME = "DTD"
DATA_TYPE = ASCII_REAL
START_BYTE = 278
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "User-specified point (TTX) to DSN (TRX)
vector in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 11
NAME = "DTS"
DATA_TYPE = ASCII_REAL
START_BYTE = 320
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "User-specified point to spacecraft vector
at TTX in J2000 coordinates."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 12
NAME = "THTI"
DATA_TYPE = ASCII_REAL
START_BYTE = 362
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
DESCRIPTION = "Incidence angle at user-specified point.
The angle between the local surface
normal and the DTS vector. Values
larger than 90 mean the spacecraft
is below the horizon."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 13
NAME = "THTS"
DATA_TYPE = ASCII_REAL
START_BYTE = 372
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
DESCRIPTION = "Scattering angle at user-specified point.
The angle between the local surface
normal and the DTD vector. Values
larger than 90 mean that the DSN
receiving site below the horizon."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 14
NAME = "BETA"
DATA_TYPE = ASCII_REAL
START_BYTE = 382
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
DESCRIPTION = "Bistatic angle at user-specified point.
Separation angle between DSN and the
spacecraft as seen at the user-specified
point. Angle between DTS and DTD."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 15
NAME = "DOB"
DATA_TYPE = ASCII_REAL
START_BYTE = 392
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Center of Mars to beta=0 (backscatter)
point in J2000 coordinates. If the beta=0
point does not exist, this vector is
undefined and BLAT and BLON should be set
to -999.9999."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 16
NAME = "BLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 434
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric latitude of beta=0 point. Set
to -999.9999 if the point does not exist."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 17
NAME = "BLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 444
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric east longitude of beta=0 point.
Set to -999.9999 if the point does not
exist."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 18
NAME = "DOR"
DATA_TYPE = ASCII_REAL
START_BYTE = 454
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Center of Mars to raypath closest approach
(RCA) point in J2000 coordinates. The
raypath is vector DSD; the RCA point is on
the surface of Mars where DSD is closest.
If the RCA point does not exist, DOR is
undefined and RLAT and RLON should be set
to -999.9999."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 19
NAME = "RLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 496
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric latitude of the raypath closest
approach point. Set to -999.9999 if the
spacecraft to DSN receiver distance is less
than the DSN receiver to center of Mars
distance."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 20
NAME = "RLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 506
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric east longitude of the raypath
closest approach point. Set to -999.9999
if the spacecraft to DSN receiver distance
is less than the DSN receiver to center
of Mars distance."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 21
NAME = "DOP"
DATA_TYPE = ASCII_REAL
START_BYTE = 516
BYTES = 41
ITEMS = 3
ITEM_BYTES = 13
ITEM_OFFSET = 14
FORMAT = "E13.6"
UNIT = "METER"
DESCRIPTION = "Center of Mars to specular point vector
in J2000 coordinates. If the specular point
does not exist, this vector is undefined and
PLAT and PLON should be set to -999.9999"
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 22
NAME = "THPI"
DATA_TYPE = ASCII_REAL
START_BYTE = 558
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
DESCRIPTION = "Incidence angle at specular point. Values
are undefined when the spacecraft is in
occultation."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 23
NAME = "THPS"
DATA_TYPE = ASCII_REAL
START_BYTE = 568
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
DESCRIPTION = "Reflection angle at specular point. Values
are undefined when the spacecraft is in
occultation."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 24
NAME = "PLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 578
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric latitude of specular point. Set
to -999.9999 if the specular point does not
exist (the spacecraft is in occultation)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 25
NAME = "PLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 588
BYTES = 9
FORMAT = "F9.6"
UNIT = "DEGREE"
INVALID_CONSTANT = -999.9999
DESCRIPTION = "Areocentric east longitude of specular point.
Set to -999.9999 if the specular point does
not exist (the spacecraft is in occultation)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 26
NAME = "DTHTI"
DATA_TYPE = ASCII_REAL
START_BYTE = 598
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
DESCRIPTION = "Partial derivative of THTI with respect to
Rp. The change in incidence angle at the
user-specified target point resulting from
a +1 m change in Mars radius."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 27
NAME = "DTHTS"
DATA_TYPE = ASCII_REAL
START_BYTE = 608
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
DESCRIPTION = "Partial derivative of THTS with respect to
Rp. The change in scattering angle at the
user-specified target point resulting from
a +1 m change in Mars radius."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 28
NAME = "DBETA"
DATA_TYPE = ASCII_REAL
START_BYTE = 618
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
DESCRIPTION = "Partial derivative of BETA with respect to
Rp. The change in bistatic angle at the
user-specified target point resulting from
a +1 m change in Mars radius."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 29
NAME = "DBLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 628
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of BLAT with respect to
Rp. The change in latitude of the
backscatter point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no backscatter point (line from
DSN station to spacecraft does not intersect
the surface)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 30
NAME = "DBLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 638
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of BLON with respect to
Rp. The change in longitude of the
backscatter point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no backscatter point (line from
DSN station to spacecraft does not intersect
the surface)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 31
NAME = "DTHPI"
DATA_TYPE = ASCII_REAL
START_BYTE = 648
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of THPI with respect to
Rp. The change in incidence angle at the
specular point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no specular point (spacecraft
is in occultation)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 32
NAME = "DTHPS"
DATA_TYPE = ASCII_REAL
START_BYTE = 658
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of THPS with respect to
Rp. The change in reflection angle at the
specular point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no specular point (spacecraft
is in occultation)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 33
NAME = "DPLAT"
DATA_TYPE = ASCII_REAL
START_BYTE = 668
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of PLAT with respect to
Rp. The change in latitude of the
specular point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no specular point (spacecraft
is in occultation)."
END_OBJECT = COLUMN
OBJECT = COLUMN
COLUMN_NUMBER = 34
NAME = "DPLON"
DATA_TYPE = ASCII_REAL
START_BYTE = 678
BYTES = 9
FORMAT = "E9.2"
UNIT = "DEGREE PER METER"
INVALID_CONSTANT = -9.99E-02
DESCRIPTION = "Partial derivative of PLON with respect to
Rp. The change in longitude of the
specular point resulting from a +1 m
change in Mars radius. Set to -9.99E-02
if there is no specular point (spacecraft
is in occultation)."
END_OBJECT = COLUMN
END_OBJECT = BSR_GEOM_TABLE
END
A.3 Example SRI Label
PDS_VERSION_ID = PDS3
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 1024
FILE_RECORDS = 300
^IMAGE = "9133H43A.SRI"
INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR"
TARGET_NAME = "MARS"
INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM"
DATA_SET_ID = "MGS-M-RSS-5-SDP-V1.0"
PRODUCT_ID = "9133H43A.SRI"
PRODUCT_RELEASE_DATE = 2000-07-28
DESCRIPTION = "This file contains a 2-D array in image
format showing power vs frequency and time around the time of a Mars
Global Surveyor radio occultation. A nominal image is made from 300
512-point power spectra where the spacing between spectra is 0.2048 s
and the frequency spanned is 2500 Hz (4.88 Hz resolution). Images
show the spacecraft carrier emerging from occultation (egress) or
disappearing as the spacecraft goes behind the limb (ingress). Near
the occultation time there may be a weak surface echo racing away from
the carrier to lower frequencies (egress) or coming in from higher
frequencies to merge with the carrier at occultation (ingress).
Keywords START_TIME and STOP_TIME give the beginning and ending of
data recording for the occultation. For exact times of each spectrum
see the Surface Reflection Table file that corresponds to this image
(same file name except for suffix .SRT).
This image was produced by R.A. Simpson of the MGS Radio Science Team."
START_TIME = 1999-05-13T07:43:00
STOP_TIME = 1999-05-13T07:55:00
SOFTWARE_NAME = "SURF2PDS;1999-10-13"
PRODUCT_CREATION_TIME = 2000-01-08T03:30:20
PRODUCER_ID = "MGS RST"
OBJECT = IMAGE
LINES = 300
LINE_SAMPLES = 512
SAMPLE_TYPE = MSB_INTEGER
SAMPLE_BITS = 16
UNIT = "DECIBEL"
OFFSET = 0.0
SCALING_FACTOR = 0.01
DESCRIPTION = "This image contains values of received
signal power versus frequency and time
in units of decibels relative to one
one watt. Values can be obtained by
multiplying the sample in the image by
SCALING_FACTOR and then adding OFFSET.
Each line in the image corresponds to
one power spectrum. The first line in
the file is the LAST spectrum. The
first point in a line corresponds to
the lowest frequency (0 Hz)."
END_OBJECT = IMAGE
END
A.4 Example SRT Label
PDS_VERSION_ID = PDS3
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 50
FILE_RECORDS = 305
^SURF_HDR_TABLE = ("9133H43A.SRT",1)
^SURF_TABLE = ("9133H43A.SRT",6)
INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR"
TARGET_NAME = "MARS"
INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM"
DATA_SET_ID = "MGS-M-RSS-5-SDP-V1.0"
PRODUCT_ID = "9133H43A.SRT"
PRODUCT_RELEASE_DATE = 2000-07-28
DESCRIPTION = "This file contains measurements
of surface echoes obtained in the course of Mars Global Surveyor
radio occultation observations. The time of geometric occultation
and the sense of occultation (ingress or egress) were determined
from high time resolution analysis of the carrier amplitude.
A search was then made on either side of the carrier; if more
power was found on one side, that was assumed to be from the echo.
An estimate of the thermal noise background was obtained from the
other side; that, in conjunction with an estimate of system
temperature was used to calibrate the measurements. The table
contains estimates of the peak frequency bin and the amplitude
of both the carrier and the surface echo as a function of time.
For more information on bistatic radar probing of planetary
surfaces, see Simpson (IEEE Transactions on Geoscience and Remote
Sensing, 31, 465-482, 1993)."
START_TIME = 1999-05-13T07:43:00
STOP_TIME = 1999-05-13T07:55:00
SOFTWARE_NAME = "SURF2PDS;1999-10-13"
PRODUCT_CREATION_TIME = 2000-01-08T03:30:20
PRODUCER_ID = "MGS RST"
OBJECT = SURF_HDR_TABLE
ROWS = 1
COLUMNS = 24
ROW_BYTES = 222
ROW_SUFFIX_BYTES = 28
INTERCHANGE_FORMAT = ASCII
DESCRIPTION = "The SURF header contains ancillary data
associated surface echo power measurements. Each header includes
a single row of 24 data columns (220 total bytes), 28 ASCII blank
characters to pad out the record, and an ASCII carriage-return
line-feed pair at the end."
OBJECT = COLUMN
NAME = "START TIME"
COLUMN_NUMBER = 1
DATA_TYPE = TIME
START_BYTE = 1
BYTES = 19
UNIT = "N/A"
DESCRIPTION = "The Earth Receive Time at which
the first radio occultation data sample was acquired."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "STOP TIME"
COLUMN_NUMBER = 2
DATA_TYPE = TIME
START_BYTE = 21
BYTES = 19
UNIT = "N/A"
DESCRIPTION = "The Earth Receive Time at which
the last radio occultation data sample was acquired."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "OCCULTATION TIME"
COLUMN_NUMBER = 3
DATA_TYPE = ASCII_REAL
START_BYTE = 41
BYTES = 12
FORMAT = "F12.6"
UNIT = "SECOND"
DESCRIPTION = "The Earth receive time when
the geometrical ray path grazed the limb. At this point
half of the Fresnel zone was presumably obscured, and
received carrier power should have been one-fourth of its
free space value. The time was computed using power versus
time output from the POWERFIT program. Maximum and minimum
minimum carrier amplitudes within 3 seconds of the occultation
established the amplitude range. For egress, the last sample
below the 25 percent threshold served as a temporary marker.
For ingress, working in time reverse order, a similar marker
was found. The final occultation time was the time of the
adjacent sample in the unocculted (free space) direction,
usually with higher carrier power. Formal accuracy of this
quantity is estimated to be +/-12.8 msec, the POWERFIT sample
spacing. However, this method does not account for effects
of the atmosphere at the limb; refraction is estimated to
advance the occultation time by about 2 seconds on egress
and to delay it by about 2 seconds on ingress."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "ORBIT NUMBER"
COLUMN_NUMBER = 4
DATA_TYPE = ASCII_INTEGER
START_BYTE = 54
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Orbit number from which the data
were acquired; set to zero if not known. NB: Orbit numbers
were reset to 1 at the beginning of the MGS Mapping Phase
(9 March 1999)."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "DSN ANTENNA NUMBER"
COLUMN_NUMBER = 5
DATA_TYPE = ASCII_INTEGER
START_BYTE = 60
BYTES = 2
FORMAT = "I2"
UNIT = "N/A"
DESCRIPTION = "Number of the DSN antenna used
to collect the data (e.g., 14, 43, 65, ...)."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "OCCULTATION SENSE"
COLUMN_NUMBER = 6
DATA_TYPE = CHARACTER
START_BYTE = 64
BYTES = 1
FORMAT = "A1"
UNIT = "N/A"
DESCRIPTION = "The sense of the occultation:
set to 'I' for ingress or to 'E' for egress."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "ODR FILE NAME"
COLUMN_NUMBER = 7
DATA_TYPE = CHARACTER
START_BYTE = 68
BYTES = 12
FORMAT = "A12"
UNIT = "N/A"
DESCRIPTION = "File name of the original
open-loop data."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "FILTER FILE NAME"
COLUMN_NUMBER = 8
DATA_TYPE = CHARACTER
START_BYTE = 83
BYTES = 12
FORMAT = "A12"
UNIT = "N/A"
DESCRIPTION = "File name of the equalizing filter
used to smooth the output spectrum."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "CARRIER TO NOISE RATIO"
COLUMN_NUMBER = 9
DATA_TYPE = ASCII_REAL
START_BYTE = 97
BYTES = 6
FORMAT = "F6.2"
UNIT = "DECIBEL PER HERTZ"
DESCRIPTION = "Estimate of unocculted carrier
power to thermal noise power. An indication of overall data
quality."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "SYSTEM TEMPERATURE"
COLUMN_NUMBER = 10
DATA_TYPE = ASCII_REAL
START_BYTE = 104
BYTES = 6
FORMAT = "F6.2"
UNIT = "KELVIN"
DESCRIPTION = "System temperature assumed in
calibrating data to units of watts. This quantity is obtained
in real time by the NASA Deep Space Network, but values
appropriate for interpreting a given observation are not always
available. A value of 30K is considered nominal."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "SAMPLE SPACING"
COLUMN_NUMBER = 11
DATA_TYPE = ASCII_REAL
START_BYTE = 111
BYTES = 8
FORMAT = "F8.6"
UNIT = "SECOND"
DESCRIPTION = "Time spacing of the complex samples
used as input to this analysis. Spacing is twice the spacing of
the original (real) samples."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "TRANSFORM LENGTH"
COLUMN_NUMBER = 12
DATA_TYPE = ASCII_INTEGER
START_BYTE = 120
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Number of points in each power
spectrum. Typically a number like 512."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "TIME PER SPECTRUM"
COLUMN_NUMBER = 13
DATA_TYPE = ASCII_REAL
START_BYTE = 126
BYTES = 8
FORMAT = "F8.6"
UNIT = "SECOND"
DESCRIPTION = "Time represented by each spectrum,
and spacing between spectra. The product of the previous two
columns multiplied by the number of spectra averaged."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "FREQUENCY RESOLUTION"
COLUMN_NUMBER = 14
DATA_TYPE = ASCII_REAL
START_BYTE = 135
BYTES = 7
FORMAT = "F7.4"
UNIT = "HERTZ"
DESCRIPTION = "Frequency resolution in each
spectrum. TIME PER SPECTRUM multiplied by FREQUENCY
RESOLUTION gives the number of spectra averaged incoherently."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "LOWEST NOISE BIN"
COLUMN_NUMBER = 15
DATA_TYPE = ASCII_INTEGER
START_BYTE = 143
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Lowest frequency bin included in
calculation of radio thermal noise background level. Noise
bins should be on opposite side of carrier from surface echo."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "HIGHEST NOISE BIN"
COLUMN_NUMBER = 16
DATA_TYPE = ASCII_INTEGER
START_BYTE = 149
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Highest frequency bin included in
calculation of radio thermal noise background level. Noise
bins should be on opposite side of carrier from surface echo."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NUMBER OF NOISE POINTS"
COLUMN_NUMBER = 17
DATA_TYPE = ASCII_INTEGER
START_BYTE = 155
BYTES = 8
FORMAT = "I8"
UNIT = "N/A"
DESCRIPTION = "Number of noise values used to
compute radio thermal noise background level. Number of
frequency bins (from Columns 14 and 15) multiplied by the
number of spectra gives this total."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NOISE MEAN"
COLUMN_NUMBER = 18
DATA_TYPE = ASCII_REAL
START_BYTE = 164
BYTES = 10
FORMAT = "E10.4"
UNIT = "N/A"
DESCRIPTION = "Average of the noise measurements
within the bounds defined by Columns 14-16."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NOISE STANDARD DEVIATION"
COLUMN_NUMBER = 19
DATA_TYPE = ASCII_REAL
START_BYTE = 175
BYTES = 10
FORMAT = "E10.4"
UNIT = "N/A"
DESCRIPTION = "Standard deviation of the noise
measurements within the bounds defined by Columns 14-16. For
white noise and no spectral averaging Columns 17 and 18 should
be very close."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "NUMBER OF MASKED FREQUENCY BINS"
COLUMN_NUMBER = 20
DATA_TYPE = ASCII_INTEGER
START_BYTE = 186
BYTES = 3
FORMAT = "I3"
UNIT = "N/A"
DESCRIPTION = "Number of frequency bins on each
side of the carrier that were masked during search for and fit
to the frequency track of the echo signal. If no masking
were used, splatter from the carrier would dominate the search."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "FIRST TIME BIN IN FREQUENCY FIT"
COLUMN_NUMBER = 21
DATA_TYPE = ASCII_INTEGER
START_BYTE = 190
BYTES = 3
FORMAT = "I3"
UNIT = "N/A"
DESCRIPTION = "First time bin used in search for
and fit to frequency track of the surface echo. Usually 41
for egress, variable for ingress."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "LAST TIME BIN IN FREQUENCY FIT"
COLUMN_NUMBER = 22
DATA_TYPE = ASCII_INTEGER
START_BYTE = 194
BYTES = 3
FORMAT = "I3"
UNIT = "N/A"
DESCRIPTION = "Last time bin used in search for
and fit to frequency track of the surface echo. Usually 259
for ingress, variable for egress."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "ECHO FITTED SLOPE"
COLUMN_NUMBER = 23
DATA_TYPE = ASCII_REAL
START_BYTE = 198
BYTES = 11
FORMAT = "E11.4"
UNIT = "HERTZ PER SECOND"
DESCRIPTION = "Slope of the linear fit to
surface echo position with respect to the carrier. This
is the linear coefficient a in the equation
f = a*t + b
where
f is frequency of surface echo relative to carrier
t is time from the previous even hour
b is constant coefficient (Column 24)."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "ECHO FITTED INTERCEPT"
COLUMN_NUMBER = 24
DATA_TYPE = ASCII_REAL
START_BYTE = 210
BYTES = 11
FORMAT = "E11.4"
UNIT = "HERTZ"
DESCRIPTION = "Intercept of the linear fit to
echo position with respect to the carrier. This is the
constant term b in the equation
f = a*t + b
where
f is frequency of surface echo relative to carrier
a is linear coefficient (Column 23)
t is time from the previous even hour."
END_OBJECT = COLUMN
END_OBJECT = SURF_HDR_TABLE
OBJECT = SURF_TABLE
ROWS = 300
COLUMNS = 5
ROW_BYTES = 50
INTERCHANGE_FORMAT = ASCII
DESCRIPTION = "Table contains time, bin numbers, and
amplitudes of carrier and surface echo. Calculations were based
on power spectra; typically 300 spectra were used, each having
512 frequency bins. Data are in five columns, delimited by
ASCII commas (98 bytes total); the final two positions are
occupied by an ASCII carriage-return and an ASCII line-feed."
OBJECT = COLUMN
NAME = "TIME"
COLUMN_NUMBER = 1
DATA_TYPE = ASCII_REAL
START_BYTE = 1
BYTES = 12
FORMAT = "F12.6"
UNIT = "SECOND"
DESCRIPTION = "Time at which the spectrum was
calculated, in seconds from the previous ERT midnight."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "CARRIER BIN NUMBER"
COLUMN_NUMBER = 2
DATA_TYPE = ASCII_INTEGER
START_BYTE = 14
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Number of the spectral bin with
maximum power. This is presumed to be the carrier signal,
but could, occasionally, be strong interference from a ground
source. During deep occultation, this value will be random."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "SURFACE ECHO BIN"
COLUMN_NUMBER = 3
DATA_TYPE = ASCII_INTEGER
START_BYTE = 20
BYTES = 5
FORMAT = "I5"
UNIT = "N/A"
DESCRIPTION = "Number of the spectral bin
containing the presumed peak of the surface echo. After
determination of occultation sense (ingress or egress) a
search was made of the time-frequency space in which the
surface echo should be found. Area within a few bins of
the carrier was excluded. This is the location of whatever
peak was found -- usually the surface echo when strong."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "CARRIER POWER"
COLUMN_NUMBER = 4
DATA_TYPE = ASCII_REAL
START_BYTE = 26
BYTES = 11
FORMAT = "E11.4"
UNIT = "WATT"
DESCRIPTION = "Carrier power in watts.
Obtained by summing the power in the peak bin (CARRIER BIN
NUMBER) plus three bins on either side, after removal of the
noise baseline."
END_OBJECT = COLUMN
OBJECT = COLUMN
NAME = "SURFACE ECHO POWER"
COLUMN_NUMBER = 5
DATA_TYPE = ASCII_REAL
START_BYTE = 38
BYTES = 11
FORMAT = "E11.4"
UNIT = "WATT"
DESCRIPTION = "Power in presumed surface echo.
Obtained by (1) fitting a straight line to the echo offset
frequency from the carrier [Column 3 - Column 2 multiplied
by Hertz per bin; best fit is given by coefficients in
Columns 23 and 24 of SURF_HDR_TABLE]; (2) summing powers
in approximately 7 spectral bins centered on this line.
This will be a poor estimate if the fit is not good."
END_OBJECT = COLUMN
END_OBJECT = SURF_TABLE
END