# Copyright: Public domain. # Filename: S-BAND_ANTENNA_FOR_LM.agc # Purpose: Part of the source code for Luminary 1A build 099. # It is part of the source code for the Lunar Module's (LM) # Apollo Guidance Computer (AGC), for Apollo 11. # Assembler: yaYUL # Contact: Ron Burkey . # Website: www.ibiblio.org/apollo. # Pages: 486-489 # Mod history: 2009-05-17 RSB Adapted from the corresponding # Luminary131 file, using page # images from Luminary 1A. # 2009-06-07 RSB Corrected a misprint. # # This source code has been transcribed or otherwise adapted from # digitized images of a hardcopy from the MIT Museum. The digitization # was performed by Paul Fjeld, and arranged for by Deborah Douglas of # the Museum. Many thanks to both. The images (with suitable reduction # in storage size and consequent reduction in image quality as well) are # available online at www.ibiblio.org/apollo. If for some reason you # find that the images are illegible, contact me at info@sandroid.org # about getting access to the (much) higher-quality images which Paul # actually created. # # Notations on the hardcopy document read, in part: # # Assemble revision 001 of AGC program LMY99 by NASA 2021112-61 # 16:27 JULY 14, 1969 # Page 486 # SUBROUTINE NAME: R05 -- S-BAND ANTENNA FOR LM # # MOD0 BY T. JAMES # MOD1 BY P. SHAKIR # # FUNCTIONAL DESCRIPTION # # THE S-BAND ANTENNA ROUTINE, R05, COMPUTES AND DISPLAYS THE PITCH AND # YAW ANTENNA GIMBAL ANGLES REQUIRED TO POINT THE LM STEERABLE ANTENNA # TOWARD THE CENTER OF THE EARTH. THIS ROUTINE IS SELECTED BY THE ASTRO- # NAUT VIA DSKY ENTRY DURING COASTING FLIGHT OR WHEN THE LM IS ON THE MOON # SURFACE. THE EARTH OR MOON REFERENCE COORDINATE SYSTEM IS USED DEPENDING # ON WHETHER THE LM IS ABOUT TO ENTER OR HAS ALREADY ENTERED THE MOON # SPHERE OF INFLUENCE, RESPECTIVELY. # # TO CALL SUBROUTINE, ASTRONAUT KEYS IN V 64 E # # SUBROUTINES CALLED --- # R02BOTH # INTPRET # LOADTIME # LEMCONIC # LUNPOS # CDUTRIG # *SMNB* # BANKCALL # B50OFF # ENDOFJOB # BLANKRET # # RETURNS WITH # PITCH ANGLE IN PITCHANG REV. B0 # YAW ANGLE IN YAWANG REV. B0 # # ERASABLES USED # PITCHANG # YAWANG # RLM # VAC AREA BANK 41 SETLOC SBAND BANK EBANK= WHOCARES COUNT* $$/R05 SBANDANT TC BANKCALL # Page 487 CADR R02BOTH # CHECK IF IMU IS ON AND ALIGNED TC INTPRET SETPD RTB 0D LOADTIME # PICK UP CURRENT TIME STCALL TDEC1 # ADVANCE INTEGRATION TO TIME IN TDEC1 LEMCONIC # USING CONIC INTEGRATION SLOAD BHIZ X2 # X2 =0 EARTH SPHERE, X2 =2 MOON SPHERE CONV4 VLOAD RATT STODL RLM TAT CONV3 CALL LUNPOS # UNIT POSITION VECTOR FROM EARTH TO MOON VLOAD VXSC VMOON REMDIST # MEAN DISTANCE FROM EARTH TO MOON VSL1 VAD RLM GOTO CONV5 CONV4 VLOAD RATT # UE = -UNIT(RATT) EARTH SPHERE CONV5 SETPD UNIT # UE = -UNIT((REM)(UEM) + RL) MOON SPHERE 0D # SET PL POINTER TO 0 VCOMP CALL CDUTRIG # COMPUTE SINES AND COSINES OF CDU ANGLES MXV VSL1 # TRANSFORM REF. COORDINATE SYSTEM TO REFSMMAT # STABLE MEMBER B-1 X B-1 X B+1 = B-1 PUSH DLOAD # 8D HI6ZEROS STORE PITCHANG STOVL YAWANG # ZERO OUT ANGLES CALL *SMNB* STODL RLM # PRE-MULTIPLY RLM BY (NBSA) MATRIX(B0) RLM +2 PUSH DSU RLM DMP 1OVSQRT2 STODL RLM +2 DAD DMP RLM 1OVSQRT2 STOVL RLM # R B-1 RLM UNIT PDVL # Page 488 RLM VPROJ VSL2 # PROJECTION OF R ONTO LM XZ PLANE. HIUNITY BVSU BOV # CLEAR OVERFLOW INDICATOR IF ON RLM COVCNV COVCNV UNIT BOV # EXIT ON OVERFLOW SBANDEX PUSH VXV # URP VECTOR B-1 HIUNITZ VSL1 VCOMP # UZ X URP = -(URP X UZ) STORE RLM # X VEC B-1 DOT PDVL # SGN(X.UY) UNSCALED HIUNITY RLM ABVAL SIGN ASIN # ASIN((SGN(X.UY))ABV(X)) REV B0 STOVL PITCHANG URP DOT BPL HIUNITZ NOADJUST # YES, -90 TO +90 DLOAD DSU HIDPHALF PITCHANG STORE PITCHANG NOADJUST VLOAD VXV UR # Z = (UR X URP) URP VSL1 STODL RLM # Z VEC B-1 PITCHANG SIN VXSC HIUNITZ PDDL COS PITCHANG VXSC VSU HIUNITX # (UX COS ALPHA) - (UZ SIN ALPHA) DOT PDVL # YAW.Z RLM RLM ABVAL SIGN ASIN STORE YAWANG SBANDEX EXIT CA EXTVBACT MASK BIT5 # IS BIT5 STILL ON EXTEND BZF ENDEXT # NO CAF PRIO5 # Page 489 TC PRIOCHNG CAF V06N51 # DISPLAY ANGLES TC BANKCALL CADR GOMARKFR TC B5OFF # TERMINATE TC B5OFF # PROCEED TC ENDOFJOB # RECYCLE CAF BIT3 # IMMEDIATE RETURN TC BLANKET # BLANK R3 CAF PRIO4 TC PRIOCHNG TC SBANDANT +2 # YES, CONTINUE DISPLAYING ANGLES. V06N51 VN 0651 1OVSQRT2 2DEC .7071067815 # 1/SQRT(2) UR EQUALS 0D URP EQUALS 6D SBANK= LOWSUPER # END OF LNYAIDE .001 ***