Apollo Experience Report Data Management for Post Flight Engineering Evaluation

8/8/2019 Apollo Experience Report Data Management for Post Flight Engineering Evaluation

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N A S A T E C H N I C A L N O T E NASA TN 0-7684

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APOLLO EXPERIENCE REPORT -D A T A M A N A GE M E N T FOR POSTFLIGHTENGINEERING EVALUATIONby G a l l o w a y B. Foster, Jr.Lyndon B . Johnson space CenterHozlston, T e x a s 77058

NATI ONA L AERONAUTICS AND SPACE ADMINISTRA TION WASHINGTON, D. C. M A Y 197


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1. Report No.TN D- 7684

7. Author(s)Galloway B. Foster, J r .

2. Government Accession No.

9. Perform ing Organization Name and AddressLyndon B. Johnson Space Cente rHouston, Texas 77058

19. Security Classif. (of this repor t) 20. Security Classif. (of this page)None None

12. Sponsorin g Agency Name and AddressNational Aeronautics and Space AdministrationWashington, D. C. 20546

15 . Supplementary Notes

21. NO. o f Pages17 22. Price$ 3 . 0 0

3. Recipient's Catalog No -. Report DateMav 1974

6. Performing Organization Code~~

8. Performing Organization Report No.JSC S-39310. Work Unit No.

914-11-00-00-721 1 . Contract or Grant No.

13. Type of Report and Period CoveredTechnical Note

14 . Sponsoring Agency Code

16 . AbstractTheApollo management of data fo r postflight engineering evaluation is described. The source sof Apollo telemetry data, the control of data processing by a single data team , the data techniquesused to assist in evaluation of the large quantity of data, and the operation of the data team beforethe mission and during the evaluation phase a r e described. The techniques used to ensur e theoutput of valid data and to determine areas in which data we re of questionable quality a r e alsoincluded.


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CONTENTS

Sect onSUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FLIGHT DATA MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . .

Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Data Management Team . . . . . . . . . . . . . . . . . . . . . . . . . . . .Planning for Missions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Data Management Aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mission and Postmission Operations . . . . . . . . . . . . . . . . . . . . .Data Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CONCLUDING REMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .APPENDIX-GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page1122347

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TABLES

Table Page2CHARACTERISTICS OF THE BASIC PCM SYSTEM . . . . . . . . . . .

I1 COMPARISON OF FULL RATE AND ZERO-COUNT BANDPASS 5ATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FIGURES

Figure Page81 Example of a portion of a flight data sou rce log . . . . . . . . . . . . .

2 Example of a portion of a request status maintenance report . . . . . . 93 Annotated page of flight data sou rce plot . . . . . . . . . . . . . . . . . 10

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APOLLO EXP ER l ENCE REPORTDATA MANAG EMENT FOR POSTFLIGHT ENG l NEER

B y G a l lo w a y B. Foster, Jr.L y n d o n B. J o h n s o n Sp ac e C e n t e rS U M M A R Y

NG EVALUAT ON

Apollo data management w a s based on the experience gained in the Gemini Pro-gram and w as modified to use advantageously the abundance of rea l-t ime data availableon the Apollo lunar flights. The cen tra l data management team provided the single pointof control fo r Apollo data reduction. An in-depth reduction of all flight data w a s neithereconomical nor practi cal because of the lar ge amounts of data generated on the la terApollo fligh ts. The concepts developed by the data team were as follows.

1 . To use the data from early missions to establish the chara cteri stics that de-f i n e normal system operations2 . To develop a system to afford the analysts a quick look at the overall missiondata throughout the remaining Apollo flights3 . To perform an in-depth reduction of data for those areas in which additional

analysis w a s requiredTo fulfill these objectives, the data team used quick-look techniques to identify areasneeding m or e analysis and a computer to scan data and to remove superfluous data(bandpass). Standard outputs were developed so that production methods could be usedto process data.

The method of operation used by the evaluation team began before the mission withthe planning of the data reduction. During and aft er the mission, the analysts reviewedthe quick-look da ta and submitted req ues ts for additional data . The data team consoli-dated these requests , assigned priori tie s, and submitted the consolidated requests to aprocessing organization. The data were then processed , validated, and delivered to theuser .

INTRODUCTI ONThe expe rience gained during the Gemini Prog ram in data management f or mis-sion evaluation purposes was applied to the Apollo Program. Because of the la rge ma ss


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of data acquired during Apollo miss ions and the need to evaluate thes e data, a methodw a s developed to review all data rapidly and then carefully select those data that requiredin-depth processing. In addition, the Apollo data management system accommodatedmany u ser s that included approximately 12 NASA spacecraft sy st em s analysis groupsand two major contractors, each with their own systems analysts. This report dis cuss esthe methods used in process ing Apollo engineering data and the activit ies of a centraldata management team in making the data available for mission analysis on a timely andeconomical basis. The computer te rm s used in this report a r e defined in the appendix.

FLI GHT DATA MANAGEMENT

Data SourcesTwo types of data sources are of int er es t to the data proces so r: the spacecraf t

data source s and the ground data systems.The primary source of spacecraf t data w a s the operational telemetry system.The characteris tics of the basic pulse code modulation (PCM) system used in both the

command and ser vi ce module (CSM) and the lunar module (LM) a r e given in table I.TABLE I.- CHARACTERISTICS OF THE BASIC PCM SYSTEM

Characteristic Iode of operationIBit rat e, kbps . . . . . . . . . . . .Bits/word . . . . . . . . . . . . . .Words/ frame . . . . . . . . . . . .Prime frame rate, frames/ sec . . .Subframe ra te , subframe/sec . . .

51.28

128501

Low bit rate1.68

200

Data could be transmitted in real time i n either of these modes. The CSM couldreco rd data for later t ransmissi on to the Earth. The LM did not contain a recorderbut could transmit low bit ra te data to the CSM recorde r. Other Apollo telemetry datasources were th e CSM flight qualification tape r eco rd er and the LM developmental flightinstrumentation package. The flight qualification tape re co rd er was a supplementaldata system for supplying data on the launch and entry conditions. The developmentalflight instrumentation syst em provided supplemental data to verify the proper sy st em soperation during the two initial LM flights, the Apollo 9 and 10 missions. Data reduc-tion from these sy ste ms was a short-term task that required s pecial handling.

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After being received at the ground station, the data wer e handled in two differentway s : (1) the data were routed back to the NASA Lyndon B. Johnson Space Center (JSC)(formerly th e Manned Spacecraft Center (MSC)) o as si st in the operational control ofthe mission, and (2) the data wer e recorded on magnetic tape fo r shipment to a reductionfacility. The data fo r operational control were transmit ted fr om the Manned SpaceFlight Network (MSFN) si tes by high-speed data lines . Because of limited bandwidth,the high-speed data lines available would not accommodate all spacecraft telemetry data.Two methods were used to dec re as e the amount of retr ansmitted data. In the firstmethod, data were thinned by reducing the sample ra te . In most case s, selected meas-urement s we re transmitted to MSC at one-tenth the normal sampl e rate . The secondmethod w a s to transmit only those data that were of most inter est during a particularmission phase. Thus, planned se t s of measurement/sample-rate for ma ts we re used.Each of these fo rm at s was used for a particular mission activity or function. For ex-ample, a format containing mostly CSM data w a s transmitted during translunar coast,and a for mat containing both LM and CSM data was transmitted in lunar orbit.

Data Manag em ent TeamThe Apollo data were managed by a central data management team that was es -tablished to control the reduction of all mission data. The data team w a s a conceptthat had proved effective during the Gemini Pro gram. The maj or functions of the cen-t ra l data management team that contributed to the success of the Apollo miss ion datatask a r e explained in the following paragraphs.To eliminate redundancy in data processing, request s from sever al us e rs werecombined into one request to the process ing facility, and the capabilities of the com-puter system were used fully. For example, computer systems in use could processall spacecraft telemetry measurements in a single computer run. The computer timerequired to proces s all measurements as compared to processing only a f ew w as neg-ligible. Because experience had indicated that mo re than one person w as usually

interested in data from a particular event, an analyst's request for particula r meas-urements resulted in a data management team request fo r all measurements for thattime period.Data were only processed when required for analysis. The data team, a pa rt ofthe mission evaluation team, w a s staffed with engineers who understood the princip lesof analysis. Justification w a s required when the data team believed that the requesteddata we re not required or that more data were requested than could be effectivelyanalyzed.Pr io ri ti es were established fo r data reduction requirements to ensure some ord erin dispensing the available data. Some of the factors considered in establi shing pr io r-

ities we re the importance of a quick solution to anomalies, the balance of da ta (i.e . ,one group of analysts not having mo re data than they could use while another group w a swaiting fo r data) , and the availability of the range tapes or other data sources.Data reduction was also enhanced by selecting the type of data processing outputmost applicable to the situat ion. By using thei r knowledge of the capabil ities and thest at us of the processing equipment, the other data requirements in work, and the pur-pose of the analysis the data were to support, the data team could suggest alte rnates

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for the requested process ing method. For example, an analyst (because of fami lia r-i ty with the output) might request a tabular output of a few parameters for a long seg-ment of the miss ion. After analyzing thi s request , the data team would recommend astripchart-type output fo r these data. The ba si s for this recommendation was that,fo r the particula r se t of circumstances, the suggested output would be fas te r and mor eeconomical to produce and easi er to scan and analyze. After a discussion of the situ-ation, the analyst and the data team would ag re e on the method of data process ing.

Planning for MissionsThe fi rst lunar-landing mission produced approximately 220 hours of spacecraftda taf ro m the two vehicles during the 195-hour mission. Because of the time and cost sassociated with the shipment of range tapes and the reduction of all mission data, aplan w a s required that would ensure that the evaluation could be accomplished withoutin-depth processing of all mission data. To achieve this objective, di scussions werethen held with the users to acquaint the data team with the analysis techniques and toeducate the analyst on the potentials and limi tations of the data processing systems.The evaluation concept w a s based on the assumption that there would be long pe-rio ds of routine operation, some planned periods of high int erest ac tivity, and someunplanned periods of high inte rest ac tivity. To implement thi s concept> the objectiveswere to establish what constituted normal miss ion operations, to review each missionin sufficient detail to establish periods of special interest, and to reduce data fo r de-tailed analysis of these special interest periods.A s much as possible, all data outputs were planned before the miss ion. Meas-urements were placed in related groups (normally by subsystem) fo r ea se of analysis .Tabulation, plot, and stripchart formats we re specified.Normal sy ste ms operating characteristics we re established by analysis of datafrom te st s and early Apollo flights. Because early unmanned flights were of shor tduration, most available data were processed. To aid in data validation and to ac-quaint the analyst with the strengths and weaknesses of the various output formats, thedata were also processed and displayed in se ve ra l different types of outputs.As the Apollo Program progr essed t o longer duration flights, a quick-look tech-nique was used to provide visibility into a rea s requiring further analysis. Data thatwere required for operational control of the miss ion were used in this technique. Theinitial data display w a s on a television s cre en in rea l time.essed into a hard-copy form, which was available within 4 to 12 hours after the datawere received. In addition to developing a general concept fo r managing the data, thedata management team developed seve ra l process ing techniques to as si st both the anal-y s i s and the process ing workload.

These data were a lso proc-

Bandpass techniques. - The pr ime process ing technique used fo r the Apollo P ro -gram w a s the bandpass tabulation. A bandpass tabulation is a display fo rm at that high-lights those measurements with changing values. Repetitious data points a r e omitted,and only those measurements that change by a predetermined amount a r e tabulated. Abandpass technique is used in a PCM system because it does not produce a continuous

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indication of the measurement values; it produces d isc ret e digital values (counts) at apredetermined sample rat e. This sys tem does not contain information between counts.The simplest form of a bandpass technique s cans the PC M counts transmitted andeliminates all redundant counts. This method pr in ts out the f ir st count value, holds

this value in the computer memory, and compares each success ive count to this baseuntil there is a change. No repetitive values a r e retained. The changed count isprinted and stored in the computer memory a s the new base value. This technique iscalled a zero-count bandpass. Because al l changes a re printed and all transmitteddata can be reconstructed by rein sert ing the redundant data points, no data a r e lost.A time history and a bandpass of the sa me data are given in table 11.

TABLE II. - COMPARISON OF FULL RATE AND ZERO-COUNT BANDPASS DATA

Time,hr :min:secCCO206VDirect-current voltagemain bus A

~~

cco207vDirect-current voltagemain bus BFu l l rate data

105:47:50.083105:47:50.183105:47:50.283105:47:50.383105:47:50.483105:47:50.583105:47:50.683105:47:50.783105:47:50.883105:47:50.983105:47:51.083105:47:51.183105:47 :51.283105 47 :51.383105:47:51.483

?05:47:51.583

28.2928.2928.2928.2928.2928.1028.1028.1027.9227.9227.9227.9228.1028.1028.1028.10

Zero-count bandpass data

28.0928.0928.0928.0928.0928.0928.0928.0927.9127.9127.7427.7427.7427.7427.7427.74

105:47:50.083105:47:50.583105:47:50.883105:47:51.083105 47 :51.283105:47:51.583

28.2928.1027.9228.1028.10

--~ ~~

28.0927.9127.7427.74

----

aLast value of each data interval.5


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The zero-count bandpass technique has the advantage of deleting superfluous data.Because of long per iods of quiescent system operations and because of measurementsthat by nature change slowly, approximately 80 percent of the returned data need notbe presented to the analyst. A shortcoming of this technique is that a measurementthat is noisy or rapidly changing between two counts results in an excessive output ofusele ss data. This shortcoming can be corrected by opening the bandpass limits andeliminating the insignificant da ta . This method is feasible because the instrumentationsystem operates so that a one-count change is sufficient to provide'data for off -nominalconditions. During normal operation, a change of severa l counts usually is not signif-icant in the analysis process. Limits a r e defined as standard bandpass when the ana-lysts and the data team have agreed that these lim its a r e to be used in processing themajori ty of the data.

Manned Space Flight Network data usage. - Another technique developed for theApollo Program involved taking the real-timTdata returned for mission control Pur-poses and processing the data specifically for hardware evaluation. The method ?f dis-playing MSFN data was developed primari ly f or the lunar missions because th ere werelong continuous periods of rea l-time data transmission during these missions .A s previously explained, the real-time operational data were transmitted f ro m

the receiving s it es at a reduced sample rate. These data were displayed in variousways for ground support personnel. However, f or postflight analysis purposes, the datawere routed to the central data facility for processing. After zero-count bandpass proc-essing, the data were stored in a computer memory. At regular intervals, the datawere processed with a standard bandpass technique and tabulated or plotted forevaluation.Although the MSFN data output provided process ing for large amounts of data,the following const raint s of the sys tem wer e required.1. Standard output formats would be established approximately 30 days beforethe mission.2. The time contained in the data s tr ea m would be used uncorrected.3 . Measurements with two or more modes of calibration would be processedwith the most common mode.4 . Only real-time data would be processed.The MSFN data were available at 4-hour intervals in predetermined fo rmat s withpr es et bandpass limits. Two other options were available fo r limited use. One wasthe rapid processing (approximately 1 hour) of data from sh or t time periods by specialhandling and priority during the processing cycle. The other option w a s the use of the

zero-count bandpass technique also for short time periods. The requirement fo r as-signing a computer fo r the duration of the mission w a s a disadvantage of processingMSFN data.

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Special programs . - In genera l, the output of the proces sed data was a simple,straightforward presentation that w a s used by all analysts for evaluating both nominaland anomalous conditions. Some analysts required special computations fo r sy st em sanalysis . Two examples of different approaches used to meet thi s situation are dis-cussed in the following paragraphs .For the analysis of the reaction control system, standard analysis programs weredeveloped. When spec ial progra ms were required, standard computations that werenot dependent on personal judgment were used. With th is mode of dat a presenta tion,the basic system analysis was accomplished with data processed by the central comput-e r facility; therefore, additional programs were not required.For analysis of the ascent, descent, and se rv ice propulsion systems , however,the only reduced data provided w ere standard printouts of chamber pr es su re and othertelemetered propulsion pa rame te rs . To comply with the requirement for special com-putations, a computer-compatible tape w a s provided t o the MSC sy st ems analysts fo rfur the r reduction with the ir own computer progra ms. During thi s reduction, the ana-l y s t s weighted the various measurements on the basis of re su lt s from ground t es ts andprevious flight te st s. Because this method of data reduction contained a judgment fac-to r, these programs were unacceptable to other analysts who were either unfamiliarwith the weighting fac to rs or did not agr ee with the fac tor s. Consequently, other ana-l y s t s had to develop additional programs to evaluate the se propulsion syst ems , whichproved to be a continuing problem. A better solution for all analysts would have beento develop standard programs fo r special computations. Any additional computationsinvolving personal judgment could have been made to supplement the standard output.This experience emphasized the need fo r an agreement on processing all data requiredfo r the basic analysis.

Dat a M anag em en t AidsThe data team developed several aids for the m.anagement task. As input to theseaids , two types of daily teletype messa ges were requir ed from each remote s it e. Onecontained the time periods of rea l-t ime data recorded at the si te and identified the tapere co rd er . The othe r type of mes sage furnished information on the data playbacks re -ceived by each sit e. The MSFN data furnished information on the data r at e being trans-mitted by the spacecraft . The information provided by these data sou rces was used inth re e computer programs and served as a management aid for the data team.Flight data so urce log. - The flight data source log listed al l recorded telemetrytapes in time sequence generated during a miss ion. This log used information fromthe s it e teletype mess age s and listed the recording site , st ar t and stop time of eachtape, re co rd er number, type of recorded data (re al time o r delayed time), and acces-sion number of all tapes delivered to MSC. This log wa s used primarily to identify aparti cular range tape to as su re that it was sen t to MSC. An example of th is log is shownin figure 1.

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S E Q R E C O RD T A P E G M T T I M E S G ET T I M E S D A T A M I S S I O NN O. STAT N O. D S S S T A R T S T O P Y R S T A R T S T O P T Y P E P H A S E R Eb W RK .535512209333564965043 584 9736 050550650736493436 5

AC N 15-0849DUMP -------DUMP - _- -- -A CN 15-0849M A D 15-0619M A D * 15-0633ACN. 15-0850M A D 15-0620A C N 15-0851M A D * 15-0634MAD * 15-0634M A D * 15-0635A CN 15-0852D U MP -------A C N 15-0852

630 211/1849 211/1859--- 21 1 1857 21 1 1946-- - 211/1857 211/1947630 21 1 1942 21 1 1956631 211/1942 211/2027637 211/1949 211/2002630 211/1955 211/2033631 211/2026 211/2058630 21 1/203 2 21 1/2051637 211/2 032 211/2034637 21 1 2039 21 1/2 042637 21 1 205 0 21 1 205 9630 21 1 2050 21 1 2058630 21 1 2137 21 1 2152- -- 211/2112 211/2148

717171717171717171717171717171

101:15101 :23101 :23102:08102:08102:15102:21102:52102:58102:58103:05103:16103:16103:38104:03

101 :25102:12102:13102:22102:53102:28102:59103:24103:17103:OO103:08103:25103:24104:14104:18

D C LLC

D C LC LDC L

D C LC LD C LDCDC LDCDCCDC

L O R E V 12MA D 634 L B Rf l A D 633 L B RLO R E V 13~L O R E V 13LO RE V 13

L O R E V 13L O R E V 13L O R E V 13.L O R E V 13L O R E V 13LO RE V 13LO R E V 13L O R E V 14GD S 375 L B R

Notes: (1) SEQ NO. (sequence number) - A number assigned by th e data manager for in it ia lprogram entry.entry to indicate delayed-time data coverage. Record ing stat ions (Ascension (ACN),Madrid (MAD), or Goldstone (GDS)) are designated with an asterisk.)

(2 ) RECORD STAT (recording sta tio n) - Ground station that recorded data. (Dump i s a manual

(3) TAPE NO.- Number assigned by MSC after receip t of sta tion tape.(4 ) DSS (data service support) - Number assigned by network to designate missi on phaseand type of data-recorded tape (630 and 631 - real-time data for translunar coast andlunar orb it, 632 and 633 - real-time data for transearth coast, 637 - all delayed-timedata).(5) GMT TIMES - The Greenwich mean time for the data start and stop times.(6) Y R (year) - The year data were recorded.(7) GET TIMES - The ground elapsed time for the data start and stop times.(8)DATA TYPE - To indicate t he vehicl e downli nk recorded o n tape (C = CSM, L = LM, and(9)MI SS ION PHASE - LO = lun ar orbit.

(10) REMARKS - REV 12, REV 13, and REV 14 indicate revo lut ion number. MAD 634, MADD = DUMP).

633, and GDS 375 indicate th e recording stat ion and the l ast th re e digits o f th e tapenumber . LBR indicates a low bi t rate dumpFigure 1. - Example of a portion of a flight da ta source log.

Request status maintenance report. - The request status maintenance repor t con-tained a listing of data requested and included information on the request number, timeperiod, accession number of the tape used, and status of the requested data. Data werelisted in a number of ways, but the mos t widely used method was listing by the time re-quested or the request number. This repo rt was used to avoid duplication of reques ts,to provide processing status, and to assess priorities.in figure 2. A portion of this report is shown

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APOLLO 15 REQUEST STATUS AS OF 0800 10/19 /71

S B S S C : S S: B 0:L E B:A D V:P R E T MA I T T 0 : P P : R ':O X I : N I 0 : P C X R ID L D D M:L L: S G:O P O:L G 1:s S P A SQ E P : : H R :K : G C: J CB D C / V T P W:T P:C A:A T M:T T T :B B B E E/ M / T E A L D : A L : H M : N A E: / / / : / / / C LI M E ( A E T ) R EQ .S T A R T S T O P N O. S I T E R P L E L 8 T S : B T : T S : G B D:C C C:T T T T L : R E M A R K S : NO.TAPE

101 :09101 0910 1 :2 010 1 :2 2101 :23101:23101:38101:38102:08102:08102:12102:13102:49102:52102:52103:OO103:38103:38103:38103:38103:40104:03

101 :23101:25102:12101 :25102:13102:13101 :45101 :45102:53102:53102:28110:06103:40103:24103; 24103:25104:14104:31104:14104:14104: lO104:33

63 470415456336043704240 35866044704372214771 66045704463260387037603770365446039

MA DMA DMADMA DMADMADMADMADMA DMA DMA DGOSSMA DMA DMA DMADGDSGDSGDSGDSGDSGDS

H C C C CH C DL D C C C CL c c c cH O C 0H D C DL c c c cL D C CH C DH C Dc c cCH C CH C DH C DH C C C CH D C DH D C CH D C DH D C DL D C C C CH C D

C :C :C :

C:

C:

C :

C :

C:

c :

c :

FORMAT 3.9KB/S PCM ONLYCRYO TAPEFORMAT 64KB/S PCM ONLYFORMAT 3.9KB/S PCM ONLYFORMATTED ON REQ 40 3FORMAT 64KB/S PCM ONLYFORMAT 3.9KB/S PCM ONLY

C OMPR ESSED FU LL- R ATE

15-03251,252,253,067,68,69,70,71FORMAT 64KB/S PCM ONLYFORMAT 3.9KB/S PCM ONLYFORMAT 64KB/S PCM ONLYFORMAT 3.9KB/S PCM ONLYFORMAT 64KB/S PCM ONLYFORMAT 3.9KB/S PCM ONLYCRYO TAPEFORMAT 64KB/S PCM ONLY

:0061 9:00619:00633: 061 9:00633:00633:00633:00633:0061 9:00619:0061 9: M U L T I:00620: 0620:00620:00620:00376:I20376:00375:00375:DO375:00364

~

N o t e s (1) IME (AET) - Tim e of data on tape in elapsed time from nea rest whole second before l ift-off (same asGET in f igure 1).(2 ) RE Q N O . - Number assigned to data request that in i t iated processing of data.(3) SITE - Range station wh ere tape was recorded (GOSS = gr ou nd operational support system ).(4) BIR - Bi t ra te of data: H = h igh b i t ra te , L = low bit rate .(5) M P - "D " indicates data f rom a dump of the onboard reco rder .(6) IL - Ind ica tes veh ic le tha t i s the data sourc e C = command and service module and L = l u n a r

modu Ie.(7 ) Remain ing ver t ica l co lum ns - Va rio us types of data outputs th at a re requested and processing status.O n e of th e fo l lowing designat ions appears in t h e c o l u m n i f t h a t output ha s been requested: R = r e -quested; C = completed; D = requ est deleted.(8) APE NO . - Last f i ve d ig i tso f access ion number , wh ic h is the number assigned by MS C a f te r receip t

of rang e stat ion tape.Figure 2 . - Example of a portion of a request sta tus maintenance re po rt .

Flight data source plot. - The flight data sou rce plot w as a time-line plot of alldata recorded at the th re e deep-space tracking s it es (Madrid, Spain; Honeysuckle,Aus tra lia ; and Goldstone, California). Both rea l-t ime and delayed-time data were plot-ted, individual tapes were identified, and the transmitted da ta rat e and selec ted missionevents we re indicated. The request status maintenance report printout fo r the sam etime period w a s usually published on the page facing the plot. The information fo r thisplot was taken from the flight data source log, the request status maintenance report ,the dat a r a te fr om the MSFN data, and the manual inputs of mission events. A sampleof this plot is shown in figure 3.

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Vehicle7 Mission no. Spacecraft numberCI M A P D L L O 15ISC-iII P.CL .'I

7 ape number (real time)

Acquisition of signalC l f * l S

Figure 3 . - Annotated page of flight data source plot.Mis sio n and Postmission Operat ions

The mission evaluation team supported the flight con trol team during the miss ionThree types of data wer e available to the ana-nd conducted the postmission analysis.lysts during the mission.Television data. - Television data wer e available to the analysts fro m many closed-circuit television rec eive rs in the mission evaluation room. These rec eiv ers displayedmiss ion control data. The for mat s of these disp lays were established and controlledby the flight controll ers. Most displays wer e grouped by subsys tem, so that each ana-lyst had data of his part icular int eres t displayed. A Polaroid ca mer a, controlled by thedata manager, provided a limited hard-copy capability.Summary messag es. - Summary messages were distributed in the form of teletypetransmissio ns. Each message was generated by a particular flight controller a t hisdiscretion and contained the telemetered values of preselected mea sur eme nts at the re-quested time. These mes sag es were received by the analyst within minutes of beingproduced and provided printed da ta points.Manned Space Flight Network data. - The MSFN data we re originated specificallyfo r mission evaluation team use. The sys tem s analysts reviewed these data and deter-mined the areas in which more detailed anal ysis was required. Requests fo r postflightdata fro m these areas were made to the data team.The data team received these re ques ts, combined them with requ est s from otheranalysts, ordered the range tape, and transmitted the data request to the selected proc-essing organization. The data team reviewed the proce ssing stat us daily and assigned

priorities for data reduction. Priority assignments were based on the most impendingproblem facing the evaluation team, the availabili ty of r ang e tapes, and the need tomaintain a balance of data among the analys ts. After dat a processi ng, these data werevalidated and delivered to the users .

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D a t a V a l i d a t i o nData validation was required to ensure that no e r r o r s were introduced by the dataprocessing equipment. Data validation identified suspec t or erroneous information thatw a s the result of ground processing o r problems with the spacecraft instrumentationsys tem. The validation process began with preflight readiness checks and continuedthrough postflight evaluations.The preflight ta sk verified the en tire processing sys tem by comparing the reduced

data with known input values with a specially prepared confidence tape. The tape wasintroduced into the sys tem as early as possible.Fo r MSFN data, the validation consisted of transmitting the data by high-speeddata lines from a remote-site data processor to MSC. The validation w a s conducted inparalle l with the flight control operation for economy and early determination of t ra ns -mission er ro r s . Normal mission procedures were used in data processing. An addi-tional check of the MSFN data process ing was made by reviewing data reduced duringthe countdown demonstration tes t. This validation used actual spacecraf t data and pro-vided additional confidence in the processing sys tem.Range tape prog ra ms were validated with the confidence tape ins tead of the r ange

tape, and normal 2ostflight procedures were used in process ing the data. Al l data out-puts were verified for data grouping, arrangement, identification, timing, and datavalue. Additionally, the use of the co rr ec t calibration information w a s verified.The postflight validation effort primarily consis ted of comparing data from differ-ent processing methods to e nsure the accuracy of these methods.process ed with a computer were compared with the sam e data processed on strip cha rts.All differences were resolved by the data team.

For example, data

The prime aid used by the data group for determining data quality was the synchro-nization and data quality tabulation. This tabulation was made from the same tape usedas an input for other processing and usually provided a good indication of the actual out-put quality. The designation of e rroneous data and the cause of the e r r o r wer e indicatedby this tabulation. With thi s information, data were som etimes recovered when specialprocessing techniques were used.

During the process ing of a data tape, data were sometimes missing for sh ort pe-ri od s of time . These time periods were indicated in the reduced data. Standard engi-neering troubleshooting techniques were used to determine and resolve instrumentationsystem problems.

CONCLUD NG REMARKSA centra l data management team with authority to approve and control da ta reduc-The technique ofion greatly improves the capability to manage la rg e amounts of data .proc ess ing only significant data is a necessity fo r economically evaluating space mis -sion s. The ear li er this technique can be instituted in the gathering, transmit ting, and

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processing system, the more advantageous it becomes. It is essentia l that preplanned,standardized, processing procedures be developed and used to proces s lar ge amountsof data rapidly. All data required for basic s ys te ms evaluation should be processe dwith techniques understood by all analysts.

Lyndon B. Johnson Space CenterNational Aeronautics and Space AdministrationHouston, Texas, January 18, 19749 4 11 00- 0- 2

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APPENDIXGlossary

Bit - a binary digit that has only two states, "0" or "1"; the sma llest piece of informa-tion produced by a PCM system

Computer-compatible tape - a digital magnetic tape produced by a computer for directuse by another computerFrame - that portion of a PCM bit stream between successive synchronization patternsIn depth - a detailed analysis of dataOutput - the final presentation of a computer programPlayback - the retrieval of data from a magnetic recorderPr ime f rame - see f rameQuick look - a rapid o r cursory evaluation of data or data processed quickly to facilita tea rapid evaluationReal time - at the s am e time the event is occurringStripchart - a data presentation technique in which measurement s a r e presented as acontinuous line on a paper st ri p; oscillograms and pen recordings are two com-mon types of s tr ip char tsSubframe - the portion of a PCM bit st re am between successive samples of those mea s-ureme nts that have the lowest sample ra teWord - the number of PCM bits assigned to each part icula r measurement; usually, inone bit stream, there is a standard word length

N A S A - L a n d e p , 1974 s- 39 3 13


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Apollo Experience Report Data Management for Post Flight Engineering Evaluation

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