KPL/SCLK
\begintext
FILENAME = "spp_sclk_0001.tsc"
CREATION_DATE = "13-Aug-2018"
SPP Spacecraft Clock Kernel (SCLK)
===========================================================================
This file is a SPICE spacecraft clock (SCLK) kernel containing
information required for time conversions involving the on-board
SPP spacecraft clock.
Version
--------------------------------------------------------
SPP SCLK Kernel Version:
SPP Version 0.1 - March 6, 2015 -- Eric Melin
Updated text to replace references to RBSP with SPP
SPP Version 0.0 - August 7, 2014 -- Eric Melin
The initial SPP spice kernel.
This file was created by using RBSPA initial kernel and
modifying the spacecraft ID.
Usage
--------------------------------------------------------
This file is used by the SPICE system as follows: programs that
make use of this SCLK kernel must 'load' the kernel, normally
during program initialization. Loading the kernel associates
the data items with their names in a data structure called the
'kernel pool'. The SPICELIB routine FURNSH loads text kernel
files, such as this one, into the pool as shown below:
FORTRAN:
CALL FURNSH ( SCLK_kernel_name )
C:
furnsh_c ( SCLK_kernel_name );
Once loaded, the SCLK time conversion routines will be able to
access the necessary data located in this kernel for their
designed purposes.
References
--------------------------------------------------------
1. "SCLK Required Reading"
Inquiries
--------------------------------------------------------
If you have any questions regarding this file or its usage,
contact:
Scott Turner
(443)778-1693
Scott.Turner@jhuapl.edu
Kernel Data
--------------------------------------------------------
The first block of keyword equals value assignments define the
type, parallel time system, and format of the spacecraft clock.
These fields are invariant from SCLK kernel update to SCLK
kernel update.
The SPP spacecraft clock is represented by the SPICE
type 1 SCLK kernel. It uses TDT, Terrestrial Dynamical Time,
as its parallel time system.
\begindata
SCLK_KERNEL_ID = ( @2018-08-13T16:37:52 )
SCLK_DATA_TYPE_96 = ( 1 )
SCLK01_TIME_SYSTEM_96 = ( 2 )
\begintext
In a particular partition of the SPP spacecraft clock,
the clock read-out consists of two separate stages:
1/18424652:24251
The first stage, a 32 bit field, represents the spacecraft
clock seconds count. The second, a 16 bit field, represents
counts of 20 microsecond increments of the spacecraft clock.
The following keywords and their values establish this structure:
\begindata
SCLK01_N_FIELDS_96 = ( 2 )
SCLK01_MODULI_96 = ( 4294967296 50000 )
SCLK01_OFFSETS_96 = ( 0 0 )
SCLK01_OUTPUT_DELIM_96 = ( 2 )
\begintext
This concludes the invariant portion of the SCLK kernel data. The
remaining sections of the kernel may require updates as the clock
correlation coefficients evolve in time. The first section below
establishes the clock partitions. The data in this section consists
of two parallel arrays, which denote the start and end values in
ticks of each partition of the spacecraft clock.
SPICE utilizes these two arrays to map from spacecraft clock ticks,
determined with the usual modulo arithmetic, to encoded SCLK--the
internal, monotonically increasing sequence used to tag various
data sources with spacecraft clock.
\begindata
SCLK_PARTITION_START_96 = ( 0.00000000000000e+00 )
SCLK_PARTITION_END_96 = ( 2.14748364799999e+14 )
\begintext
The remaining section of the SCLK kernel defines the clock correlation
coefficients. Each line contains a 'coefficient triple':
Encoded SCLK at which Rate is introduced.
Corresponding TDT Epoch at which Rate is introduced.
Rate in TDT (seconds) / most significant clock count (~seconds).
SPICE uses linear extrapolation to convert between the parallel time
system and encoded SCLK. The triples are stored in the array defined
below.
The first time triplet below was entered manually and represents the
approximate time (in TDT) at which MET = zero. The current plan for
SPP is that the given epoch will be used for both Observatory I&T
and launch. Note that the conversion from UTC to TDT used 34 leap
seconds.
\begindata
SCLK01_COEFFICIENTS_96 = (
0 @01-JAN-2010-00:01:06.184000 1.00000000000
13589166450000 @12-AUG-2018-15:23:15.029296 1.00000000000
)
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