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! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! SDDL Name: VEH_TIME_COEFF.SDDL ! ! Purpose: This SDDL file defines the veh_time_coeff relation. ! ! Modification History: ! ! Date PR Who Reason ! -------- ------- --- ------------------------------------------------- ! 05/25/98 35371 MRB Original implementation supersedes cpp8_ut_arcv ! 09/29/98 37337 MRB ref_ut is in SOGS seconds (seconds since 1980) ! 05/11/99 39037 MRB Added a second unique index for OPUS use ! 04/15/00 41339 MRB Changed major_frame_secs definition to SOGS secs !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! LANGUAGE C, FORTRAN, SQL INCLUDE ZSPSS_USER_TYPES.SDDL RECORD VEHTIME_TYPE !------------------------------------------------------------------------------ ! ! RECORD INFORMATION ! !------------------------------------------------------------------------------ DESCRIPTION "This relation contains all clock updates that were sent to the Space Telescope. These clock updates are used for command synchronization and to decipher the data. The ST clock count is a 32-bit running counter, where each count represents approximately 125 milli-seconds. To date the clock has ticked eight times a second with no drift; it was updated quarterly, we now are updating it weekly. Clock updates originate at Goddard/propagate through CCS, passed to PASS via an ASCII file, which is read by SCS and populated into this relation. CCS to PASS ICD-T1 describes the time correllation file which is the source of data for this relation. CCS uses engineering telemetry to evaluate onboard clock drift over time and also incorporates leap seconds when necessary. PASS P&S uses the spacecraft clock correlation parameters to correlate an onboard vehicle clock count with universal time, converting user-specified time tags and major frame boundaries into vehicle clock values. PASS P&S also forwards the correlation parameters to the Science Planning and Scheduling System (SPSS) for use in major frame synchronization and to the Science Data Processing (SDP) PDT for time-tagging science data. OPUS populated this relation whenever they receive the data in a science observation. The update was automatic with data processing. PASSFile/VTime now populates this relation using the time corellation file. SMSG/Generate uses this relation for SMS times (major frame synchronizations." !------------------------------------------------------------------------------ ! ! FIELD INFORMATION ! !------------------------------------------------------------------------------ FIELD ascii_ref_ut TYPE FULL_SOGS_CHAR_TIME_TYPE DESCRIPTION "This is an ASCII representation of the ref_ut time fields for user's viewing data directly." END_FIELD FIELD trans_time TYPE FULL_SOGS_CHAR_TIME_TYPE DESCRIPTION "This is an ASCII representation of the time the record was added by PASSFile/VTime. To OPUS it is the earliest the record can be used. " END_FIELD FIELD ref_ut TYPE R8 DESCRIPTION "This is the reference universal time in seconds since January 1, 1980 (SOGS seconds)." END_FIELD FIELD clock_rate TYPE R8 DESCRIPTION "This is the vehicle clock rate in seconds per count." END_FIELD FIELD clock_drift_rate TYPE R8 DESCRIPTION "This is the clock drift rate in seconds per count squared." END_FIELD FIELD clock_count TYPE R8 DESCRIPTION "This is the number of clock counts (ticks) since the defined zeroth tick. This times the clock rate gives the number of seconds since the clock was zero. This value will roll around periodically since the spacecraft has a fixed number of bits for it. The ST clock count is a 32-bit running counter, where each count represents 125 milli-seconds. In order for this counter to run for the 17 year lifetime of the Space Telescope, all 32 bits must be used. This means that one cannot use a four byte data type to contain this counter since the sign bit will be used as a part of the count (An I*4 data type would suddenly appear to be a negative number after 8.5 years.)" END_FIELD FIELD major_frame TYPE R8 DESCRIPTION "This is the major frame fiducial point in counts." END_FIELD FIELD major_frame_secs TYPE R8 DESCRIPTION "This is the major frame fiducial point in seconds since January 1, 1980." END_FIELD FIELD nssc_cnt_cyc TYPE I4 DESCRIPTION "This is the number of counts per cycle for the NSSC-1." END_FIELD FIELD df_cnt_cyc TYPE I4 DESCRIPTION "This is the number of counts per cycle for the DF-224/HST486." END_FIELD FIELD nssc_secs_cnt TYPE R8 DESCRIPTION "This is the number of seconds per count for the NSSC-1." END_FIELD FIELD df_secs_cnt TYPE R8 DESCRIPTION "This is the number of seconds per count for the DF-224/HST486." END_FIELD FIELD rts_secs_cnt TYPE R8 DESCRIPTION "This is the number of seconds count for the RTS." END_FIELD FIELD cp_secs_cnt TYPE R8 DESCRIPTION "This is the number of seconds per count for the CP." END_FIELD END_RECORD !------------------------------------------------------------------------------ ! ! RELATION DECLARATION ! !------------------------------------------------------------------------------ RELATION veh_time_coeff TYPE VEHTIME_TYPE DESCRIPTION "Vehicle Time Coefficient Relation" SUBSYSTEM_USING "SPSS", "SCS", "OPUS" INDEX veh_time_coeff_1 TYPE unique, clustered FIELDS ref_ut END_INDEX INDEX veh_time_coeff_2 TYPE unique FIELDS clock_count desc, trans_time desc END_INDEX END_RELATION !------------------------------------------------------------------------------ ! ! INSTANCE DECLARATION ! !------------------------------------------------------------------------------ INSTANCE veh_time_coeff GLOBAL TYPE VEHTIME_TYPE END_INSTANCE

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