Technical Note

Transcription

1 CO &< S8 i CO PJ < '! t-i H i M Q H U3 CO w w ESD-TR ESD RECORD COPY RETURN TO SCIENTIFIC & TECHNICAL INFORMATION DIVISION (ESTi), BUILDING 1211 ESD ACCESSION LIST ESTI Call N. AL Cpy N. f cys. Technical Nte J. H. Hclfrich LESTR-2 Telemetry Grund System 17 June 1968 Lincln Labratry MASSACHUSETTS INSTITUTE OF TECHNOLOGY Ü Lexingtn, Massachusetts ADUlMS<\

2 The wrk reprted in this dcument was perfrmed at Lincln Labratry, a center fr research perated by Massachusetts Institute f Technlgy, with the supprt f the U.S. Air Frce under Cntract AF 19(628>5167. This reprt may be reprduced t satisfy needs f U.S. Gvernment agencies. This dcument has been apprved fr public release and sale; its distributin is unlimited.

3 MASSACHUSETTS INSTITUTE OF TECHNOLOGY LINCOLN LABORATORY LESTR-2 TELEMETRY GROUND SYSTEM /. H. HELFRICH Grup 63 TECHNICAL NOTE JUNE 1968 LEXINGTON MASSACHUSETTS

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5 ABSTRACT A new telemetry grund statin identified as LESTR-2 and intended fr use with LES-5 and LES-6 satellites is described fr the purpse f defining interface requirements and available utputs. Like the previus grund statin, LESTR-2 prvides a printed paper-tape utput as well as a magnetictape utput. In additin, hwever, it includes a number f new features and utputs such as selectable-wrd printut frm a secnd printer, telephne data-set utput fr remte real-time data prcessing, and autmatic framefrmat identificatin. Accepted fr the Air Frce Franklin C. Hudsn Chief, Lincln Labratry Office 111

6 LESTR-2 TELEMETRY GROUND SYSTEM I. LESTR-2 GENERAL DESCRIPTION mdel. LESTR-2 is the _Lincln J]xperimental_Satellite T_elemetry Receiver - 2nd It is intended t accept the rf telemetry signal utput f LES-6 and frm this prvide the fllwing: (a) Printut n paper tape f all telemetry data. (b) Printut n a separate auxiliary paper tape f selected telemetry data. (c) Magnetic-tape recrding f all telemetry data. (d) Data set utput f telemetry data fr real-time cmputer prcessing via telephne link. (e) Cmmand system synchrnizatin. A blck diagram f the verall system is shwn in Figure 1. Except fr the auxiliary paper-tape printer, LESTR-2 is cntained within a single cabinet which can be rlled between lcatins as required. The Lgic Unit has been implemented with TTL integrated-circuit lgic and has been designed fr peratin with either LES-5 r LES-6. While the basic input circuitry fr prcessing the incming telemetry data stream is very simi- lar t that in the previus grund statin, a number f refinements and additins have been made t the verall system. These include facility fr printut f selected data n a secnd paper tape printer, facility fr peratin f a data set telephne link t the cmputer center fr real-time data prcessing, and facility fr detectin and utput f frame and frmat identificatin. II. LOGIC UNIT INPUT Input t the Lgic Unit frm the RF Unit is prvided n tw lines: data and clck. Bth lines must switch TTL inputs in the Lgic Unit. The data is nn- return-t-zer. etry signal. The clck is a 100 Hz square wave lcked t the LES-6 telem- The negative transitins f this clck signal time sampling f the data line state within the Lgic Unit, i.e. at each negative transitin, the state

7 f the data-line input is sampled. If the state is identical t that at the previus sampling time, a binary zer is sensed; if different, a binary ne is sensed. The Lgic Unit includes n clck-data phase adjustment and therefre depends upn prper phase relatin being established in the RF Unit. The clck-line input is used as a basis fr all timing within the Lgic Unit and fr this purpse bth psitive and negative transitins are used fr timing. By utilizatin f bth transitins, a synchrnized ZOO hz clck is derived t cntrl magnetic recrding and data set transmissin. The squareness and frequency at the clck input must therefre be cntrlled accrdingly and must nt include any spurius transitins f sufficient magnitude t switch the TTL input circuitry. III. LESTR-2 TELEMETRY DATA IDENTIFICATION Telemetry data frm LES-5 and LES-6 is identified accrding t Figure 2. The illustrated hierarchy f rganizatin cnsists f bits, wrds, frames, frmats and grups. Within each level f data rganizatin, sequential identificatin is made starting with the cunt zer. 1 wrd = 8 bits, 0 t 7 1 frame = 32 wrds, 0 t 31 1 frmat = 8 frames, 0 t 7 fr LES-6 = 4 frames, 0 t 3 fr LES-5 1 grup = 8 frmats, 0 t 7 fr LES-6 = 16 frmats, 0 t 1 5 fr LES-5 Starting with the cunt zer is significant in that previus frame and frmat identificatins have been made starting with the cunt 1. The change has been made primarily because the numerus frame-frmat identificatins within LESTR-2 culd be implemented mst simply in this manner. Althugh the LESTR-2 Lgic Unit has been designed fr receipt f bth LES-6 and LES-5 telemetry, cmpliance with LES-6 requirements has been emphasized. Accrdingly the frame frmat cunt is made n the basis f LES-6 nly, i.e. 8 frames/frmat, 8 frmats/grup. The resulting cunt is

8 an ctal frame cunt f the 64 frames making up a grup fr bth LES-6 and LES-5. Wherever a frame-frmat cunt is prvided as an utput r required as a switch setting, it is as this ctal cunt, even if the system is synchr- nized t LES-5 telemetry. The relatin f LESTR-2 frmat-frame identificatin t LES-5 and 6 iden- tificatin is listed in Table 1, where LES-5 and 6 cunts are defined as start- ing with ne. The LESTR-2 frmat-frame identificatin is generally assciated with the wrd cunt within a frame t identify a wrd, The resultant LESTR-2 wrd identificatin therefre cntains up t fur digits which prvide a cncise iden- tificatin f bth LES-5 and 6 wrds, e. g. LESTR-2 Wrd 1528 = Wrd 28 in LESTR-2 frame 5 f LESTR-2 frmat 1 Frm the relatins f Table 1, the fllwing equivalences are als valid. LESTR-2 Wrd 1528 = Wrd 28 in decimal frame 13 = Wrd 28 in LES-5 frame 2 f LES-5 frmat 3 Wrd 28 in LES-6 frame 6 f LES-6 frmat 1 LESTR-2 Wrd 528 = Wrd 28 in LESTR-2 frame 5 f all frmats Wrd 28 in LES-6 frame 6 f all LES-6 frmats Fr a wrd t repeat nce per LES-5 frame, it must be included twice per LES-6 frame, e.g. LESTR-2 Wrd 1/528 = Wrd 28 in LESTR-2 frames 1 and 5 f all frmats = Wrd 28 in LES-5 frame 2 f all LES-5 frmats

9 Fr wrds repeating every frame, the wrd identificatin is simplified further, e. g. LESTR-2 Wrd 28 = Wrd 28 f all frames and frmats IV. FRAME SYNCHRONIZATION Frame synchrnizatin infrmatin is prvided within each telemetry frame by wrds 00 and 31. These wrds cnsist f a fixed bit pattern transmitted every ther frame and the cmplement f this pattern in intervening frames. The specific pattern is shwn in Figure 3. Frame synchrnizatin is accmplished by a cntinuus check f the incming bit stream fr the pattern defined in Figure 3. If data is received withut errr, the pattern will be fund nce every ther frame and when it is, the wrd identificatin shwn in Figure 3 is assumed t exist and the bit and wrd cunters within LESTR-2 are reset accrdingly. This methd f frame synchrnizatin is similar t that used previusly and assumes negligible prbability f spfing by any telemetry data bit patterns. V. FRAME-FORMAT COUNT SYNCHRONIZATION The Lgic Unit f LESTR-2 includes facility t cunt frames and frmats being received and t synchrnize this cunt autmatically. Cunting is accmplished by a three-stage binary frame cunter fllwed by a three-stage binary frmat cunter, the frame cunter being advanced at the end f each frame. Synchrnizatin f the cunters is manually cntrlled by the "Frame- Frmat Sync Cntrl" switch n the LESTR-2 panel. Three psitins are available: "LES-5", "OFF", and "LES-6". With "LES-6" selected LESTR-2 will check the cntent f wrd 1 in every frame received. Upn detectin f all nes (decimal 2 55) fllwed by a prper check wrd (wrd 5), frame zer is identified and the frame cunter reset t zer. Similarly LESTR-2 will check the cntent f wrd 6 f the first frame f every frmat received. Again, upn detectin f all nes fllwed by a

10 prper check wrd (wrd 10), frmat zer is identified and the frmat cunter reset t zer. With "LES-5" selected, peratin is similar. Fr frame cunter sync, the cntent f wrd 2 f every frame is checked. Upn detectin f (decimal 64) fllwed by a prper check wrd, frame zer is identified. Hwever, since a LES-5 frmat cntains nly fur frames rather than eight, nly the first tw stages f the LESTR-2 frame cunter are reset t zer. Fr frmat cunter sync, the cntent f wrd 7 f every frame fr which the first tw stages f the frame cunter read zer is checked. Upn detectin f (decimal 244) fllwed by a prper check wrd, frmat zer is identified and the frmat cunter, as well as the third stage f the frame cunter, is reset t zer. With "OFF" selected, n synchrnizatin is prvided and the frame and frmat cunters are allwed t free run. VI. PAPER TAPE PRINTOUT The paper-tape printut f LESTR-2 is illustrated in Figure 4. Data wrds, tgether with frmat, frame, and wrd cunt fr each are printed fr wrds 1 thrugh 30 f each frame. Wrds 31 and 00 are fr synchrnizatin nly and are nt printed. Hwever, at the beginning f each frame during wrd 00, time-f-day infrmatin is printed as shwn. LESTR-2 checks the cntent f check wrds 5, 10, 15, 20, 2 5, and 30 and if the cntent is nt crrect, a "- " is printed t the right as shwn. This indicates an errr in the preceding set f fur data wrds. Selected data printut is prvided as an auxilliary utput frm a separate printer. In this case, printut entries fr selected wrds are identical t thse in Figure 4, except that printut is restricted accrding t the selectin made. Up t five wrds may be selected by panel switches set t the apprpriate LESTR-2 wrd identificatin. Selectin f LESTR-2 wrd XX00 (where XX is any desired frmat-frame cunt) will result in printut f time-f-day infrmatin.

11 S lng as the frmat-frame cunt is synchrnized with either LES-5 r LES-6, the frmat-frame cunt will be printed ut as shwn in Figure 4. Hwever, if synchrnizatin is inhibited by setting the "Frame-Frmat Sync Cntrl" t "OFF", frmat-frame cunts will nt be printed and an entry f "-- " will be printed instead. As an adjunct t the auxilliary printer, a strip chart recrder and D/A cnverter is included. This will allw pltting f telemetry data vs. time frm a single selected channel. VII. MAGNETIC TAPE OUTPUT The manner in which telemetry data is recrded fr magnetic tape utput is defined in Figure 5. Each frame f recrded data crrespnds t ne frame f received telemetry data and includes time-f-day and site identificatin infrmatin as well as received telemetry data. Telemetry data, and all ther infrmatin, is recrded in BCD cde as indicated. Tw mdes f nrmal recrding are prvided. Selectin is determined by setting f the "Frame-Frmat Sync Cntrl" switch, which als cntrls the mde f frame-frmat cunter synchrnizatin as discussed with regard t frame-frmat cunt. With the "Frame-Frmat Sync Cntrl" switch in either the "LES-5" r "OFF" psitin, data will be recrded as previusly recrded fr LES-5, i.e. n frame-frmat cunt infrmatin will be recrded and a P r F will be recrded after every check wrd t indicate whether the check wrd has passed r failed a check fr prper cntent. With the switch in the "LES-6" psitin, data will be recrded as defined in Figure 5 with frame and frmat cunt infrmatin included. As an indicatin f this recrding mde, a "K" is substituted fr the "S" in character 12. Als n P r F indicatin will be recrded. This has been mitted t limit the amunt f recrded data and because a check f the telemetry check wrd can be made by tape prcessing prgrams.

12 Nrmal recrd length fr LESTR-2 is 2 56 frames. A recrd will always begin with frame zer f frmat zer as indicated by the frame-frmat cunters. Once begun, a recrd cannt be terminated until the required 2 56 frames are cmpleted. This crrespnds t fur grups f 64 frames and will require a run f apprximately 11 minutes. When tape is laded, a beginning-f-tape gap f at least 3.4 inches beynd the beginning-f-tape marker will be prduced autmatically. Thereafter, a recrd gap will be inserted by LESTR-2 at the end f each recrd. At the end f a tape, ne r mre file gaps will be inserted by manual peratin f the recrder. All recrdings will be made n 1200-ft reels which will allw apprximately 18 hurs f cntinuus recrding. Fr unattended peratin, LESTR-2 includes facility fr recrding during a preselected interval. This feature utilizes the time-f-day clck required fr recrding time infrmatin. Fr recrding test data, LESTR-2 als includes facility fr recrding shrt recrds cnsisting f a single frmat r a single grup nly upn pushbuttn cmmand. VIII. TELEPHONE DATA SET OUTPUT Fr real-time cmputer prcessing f telemetry data, LESTR-2 cntains a 103 Data Set which can feed data directly t a terminal in the Lincln Labratry cmputer center. The data set signal is defined in Figure 6. Data is transmitted as 8-bit wrds, ne wrd being transmitted fr every telemetry wrd received. T prvide time-f-day infrmatin t the cmputer, telemetry check wrds are replaced by the time-f-day infrmatin and a singlebit indicatin f check wrd cntent as determined by LESTR-2. Frame synchrnizatin is prvided by alternate sets f all nes and all zers transmitted in wrd 31 f each frame. When enabled, transmissin will always begin with wrd 31. Further, the first wrd 31 will always cnsist f all nes.

13 Transmissins will terminate at the end f wrd 30. Since data wrds within each frame may als cnsist f all nes r zers any synchrnizatin prgram must check the peridicity f true sync t avid being spfed. Errr checking is prvided by parity bits shwn in Figure 6. A single parity bit is transmitted at the end f wrd 0 t prvide an dd parity check ver wrds 31 and 0. Als a single parity bit is transmitted at the end f each timef-day wrd t prvide an dd parity check ver this and the preceding set f fur data wrds. Since this latter parity extends ver 5 x 8 r 40 bits, it is nt a very pwerful check. Hwever, a mre sphisticated and cnsequently mre cmplex check des nt appear warranted fr initial peratin. IX. COMMAND SYNC OUTPUT Operatin f the grund cmmand system requires synchrnizatin with peratin f the satellite telemetry. Fr this purpse, tw utputs are available frm LESTR-2: a slw cmmand sync and a fast cmmand sync. These are defined in Figure 7. Fr the slw cmmand sync, LESTR-2 includes switch cntrl f the utput plarity. Fr fast cmmand sync, a rtary switch is included t prvide incremental delays in the 6.25 Hz square wave utput frm 0 t 140 ms in 20 ms steps. 8

14 TABLE 1 LESTR-2 Frmat-Frame Identificatin Decimal LESTR-2 LES-5 LES-6 Decimal LESTR-2 LES-5 LES-6 Fr. Cunt Fr.-Fr. Fr. Fr. Fr«-Fr. Fr. Cunt Fr.-Fr. Fr.-Fr. Fr.-Fr ~

15 STRIP CHART RECORDER TIME-OF-DAY CLOCK AUXILIARY PAPER TAPE PRINTER RF UNIT LOGIC UNIT PAPER TAPE PRINTER MAGNETIC TAPE RECORDER 103 DATA SET COMMAND SYSTEM SYNC Fig. 1. LESTR-2 blck diagram. 10

16 WORD (8 bits, 80 msec) JIT U- 10 r I ' I» 1» I «H I «I T I B6 5ST WORD ERROR DETECTION WORDS FRAME (32 wrd», 2.56 sees) ~4J5[6 7 B 9 lo 11 1? IS 1«is l«17 )B~i Z2 21Z«25[ FRAME SYNC WORDS- FRAME LES-6 FORMAT (8 frames, l s sees) (t) (2) (3) (4) (S) (6) (7) ( ) LES-6 GROUP (64 frames, sees) I ' I 2 I» I 4 S 6 7 («I (1) (21 (3) (4) (5) (6) (7) J LES-5 FORMAT (4 frames, sees) FRAME - I "" I 0/4 1/9 2/g 3/7 (1) (2) 13) (4) LES-5 FORMAT, LES-5 GROUP (64 frames, sees) (16) (1) (2) (3) (4) (3) (6) (7) (8) (9)(IO)(ll)(l2>fl3l(14)(lS) 0 0 l l «««' '1 Parenthetical Frame And Frmat Numbers Indicate Crrespnding Identificatin In Satellite Telemetry Systems Fig. 2. LESTR-2 data identificatin. 11

17 3-63-»656 TELEMETRY BIT STREAM ^ INTO LESTR-2 lootoolo 11O0O111 N. / N I ' WORD 00 FRAME N WORD 31 FRAME N-l 30 WORDS ' 240 BITS N ' WORD 00 FRAME N-l N 1 ' WORD 31 FRAME N-2 Fig. 3. Telemetry frame sync pattern. 12

18 «* FORMAT FRAME WORD NO. NO. NO. (0-7) (0-7) (1-30) DATA WORD 13-3-a«57[ LESTR-2 WORD IDENTIFICATION I I 0 6 I I 2 3 CHECK WORD ERROR INDICATION HOUR MINUTE SECOND MILLISECOND' (Hypthetical data shwn) Printut accrding t LES-6 telemetry, I.O., 8 frames/frmat, 8 frmats/grup Equals ctal frame cunt fr bth LES-5 and LES-6 **Tlme at which bit 0 f wrd 00 frm satellite is sampled at LESTR-2 Lgic Unit Input. Fig. 4. LESTR-2 paper tape printut. 13

19 1 START OF FRAME » ] r- t/1 a z y i/> O V) a z UJ tn in UJ t- Z 2 O t UJ r- =3 Z 3 cr =3 O </> <r O X U7 O UJ in 2 O <n u UJ in 3 O </1 UJ If) 2 6 z UJ r- 0) v. V) z UJ 2 < Q- U. 6 h- < 2 cr u_ * 13 * 14 * O O <! < < < r- h t- < a a 3 < < a 3 a Q Q s < Q Q CM 00 (M ro P" - ) IT, T <r <r.n io <r> 1 f~y n Q O n n n n rr IT rr rr * O O * * 'i * * * * * i i s * * N» (wrds 6-25) 1 Jh END O 8 O O 8 O 8 c <* < CD <T> s a ci.r 01 a^ s s Q a a a a Q s f~ a fm t\j M CM 1\J M r> Q Ci n n O n n n (T fr O (T Q A ir a rr fr * 8 * * * i* 1 * * * * * * * * Ü Frame - Frmal Syne Cntrl Switch Selling Char. 12 Char. 13 and 14 P/F Char. Char. per Frame LES-5 Off LES-6 S s K Omitted Omitted Included Included Included Omitted All Recrding 7-Track BCOIC, Even Parity, 200 BPI Nrmal Recrd Length : 256 Frames (4 grups) Fig. 5. LESTR-2 magnetic tape utput. 14

20 DATA SET FRAME SYNC -. ALL It WORD AT END OF ODD NUMBERED FRAMES ALL Os WORD AT END OF EVEN NUMBERED FRAMES (Transmissin begins with wrd 31 t end t dd frame, i.e., with an all Is wrd ) ODD PARITY /- OVER WO WS 0-7) (0-7),/ 31-0 ALL Is - ALL Ü1 FORMAT ' FRAME ' 0 P 31 0 ODD PARITY OVER WORDS DATA WORO 1 DATA WORD 2 OATA WORD 3 DATA WORD 4 HRS «10 ip/ 0 0 p DATA *ORD 6 DATA WORO 7 DATA WORD 8 DATA WORD 9 HRS it ;P/ 0 0 p A V DATA WORD 11 DATA WORD 12 DATA WORD 13 DATA WORD 14 MINS «10 >/f\ 0 0 p DATA WORD 16 DATA WORD 17 DATA WORD 18 DATA WORD 19 MINS 11 J^JO 0 p DATA WORD 2 1 DATA WORD 22 DATA WORD 23 DATA WORD 24 SECS 10 ;5f j 0 0 p DATA WORD 26 DATA WORD 27 DATA WORD 28 DATA WORD 29 SECS «1 ;Rfj 0 0 p V n A 1 IF CORRESPONDING CHECK WORD FROM SATELLITE SATISFACTORY, 0 OTHERWISE All Data Wrds in Binary Frm All Other Wrd«in BCD Frm All Infrmatin Transmitted mst Significant Bit First TRANSMITTED DATA ON BA CIRCUIT TO DATA SET : SPACE (0) - MARK (1)- in BIT WORD -35 MSEC- ) 5 MSEC (200 BPS) One Wrd Transmitted fr Each Telemetry Wrd Received frm Satellite. Bit Rate Derived frm Satellite. Fig. 6. LESTR-2 utput t telephne data set. 15

21 3-83-JJ60 SLOW COMMAND SYNC + SLOW COMMAND SYNC MSEC FAST COMMAND SYNC (6.25 Hz square way«) 80 MSEC- K- 160 MSEC ADJUSTABLE SYNC DELAY (0-140 msec, 20-miec Increments) REFERENCE TIME = TIME AT WHICH BIT 0 OF WORD 00 FROM SATELLITE IS SAMPLED AT LESTR-2 LOGIC UNIT INPUT (equal t recrded time) Sync Output» Frm TTL Timing Derived Frm Satellite Fig. 7. LESTR-2 cmmand sync utput. 16

22 UNCLASSIFIED Security Classificatin DOCUMENT CONTROL DATA - R&D (Security classificatin l title, bdy l abstract and indexing anntatin must be entered when the verall reprt is ctaeetlted) I. ORIGINATING ACTIVITY (Crprate authr) Lincln Labratry, M.I.T. 3. REPORT TITLE 2a. REPORT SECURITY CLASSIFICATION Unclassified 2b. GROUP Nne LESTR-2 Telemetry Grund System 4. DESCRIPTIVE NOTES (Type l reprt end inclusive dates) Technical Nte S. AUTHORIS) (Last name, tirst name, initial) Helfrich, Jhn H. 6. REPORT DATE 17 June 1968 TOTAL NO. OF PAGES 22 7b. NO. OF REFS Nne 8a. CONTRACT OR GRANT NO. AF 19(628)-5167 b. PROJECT NO. 649L 9a. ORIGINATOR'S REPORT NUMBER(S) TN b. OTHER REPORT NO(S) (Any ther numbers that may be assigned this reprt) ESD-TR AVAILABILITY/LIMITATION NOTICES This dcument has been apprved fr public release and sale; its distributin is unlimited. It. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY Nne Air Frce Systems Cmmand, USAF 13. ABSTRACT A new telemetry grund statin identified as LESTR-2 and intended fr use with LES-5 and LES-6 satellites is described fr the purpse f defining interface requirements and available utputs. Like the previus grund statin, LESTR-2 prvides a printed paper-tape utput as well as a magnetic-tape utput. In additin, hwever, it includes a number f new features and utputs such as selectable-wrd printut frm a secnd printer, telephne data-set utput fr remte real-time data prcessing, and autmatic frame-frmat identificatin. 14. KEY WORDS telemetry grund system LESTR-2 satellite telemetry receiver 17 UNCLASSIFIED Security Classificatin