SUBJ: GPS STATUS 25 JUL 90
1. SATELLITES, PLANES AND CLOCKS (CS=CESIUM RB=RUBIDIUM):
SLOTS MAY NOT BE FINAL UNTIL AFTER 21-SATELLITE REPHASING
A. BLOCK I : PRNS  3,  6,  9, 11, 12, 13
   PLANE   : SLOT D1, A3, A2, C2, A1, C1
   CLOCK   :      RB, RB, RB, CS, CS, CS
B. BLOCK II: PRNS  2, 14, 16, 17, 18, 19, 20
   PLANE   : SLOT B2, E1, D2, F2, F3, A4, B3
   CLOCK   :      CS, CS, RB, CS, CS, CS, CS
2. CURRENT ADVISORIES (ADV) AND FORECASTS (FCST):
INFORMATION IS REPEATED FOR SEVEN DAYS AFTER EVENT CONCLUDES
NANU      MSG DATE/TIME   PRN    TYPE  SUMMARY
126-90172 211629Z JUN 90  ALLSV  FCST  TESTING  175/0000-240/0000
139-90193 121330Z JUL 90  PRN6   ADV   UNUSABLE 193/1000-193/1100
140-90194 120300Z JUL 90  PRN11  ADV   UNUSABLE 194/0159-194/0212
141-90194 131700Z JUL 90  PRN18  FCST  UNUSABLE 200/1600-201/1200
142-90198 171356Z JUL 90  PRN18  FCST  UNUSABLE 200/1000-201/0400
143-90198 181327Z JUL 90  PRN13  ADV   UNUSABLE 198/2046-198/2100
144-90202 211000Z JUL 9O  PRN11  ADV   UNUSABLE 202/0901-202/0915
145-90205 241000Z JUL 90  PRN13  ADV   UNUSABLE 205/0748-205/0805
146-90205 241700Z JUL 90  PRN12  ADV   UNUSABLE 205/1350-205/1415
3. REMARKS:
A. NANU# 142-90198 CORRECTS NANU# 141-90194 PRN18 OUTAGE TO
READ UNUSABLE 200/1000-201/0400.
B. IMPLEMENTATION OF STANDARD POSITIONING SERVICE:
THE CURRENT GPS CONSTELLATION BEGAN BROADCASTING NAVIGATION
MESSAGES AT ACCURACY LEVELS CONSISTENT WITH STANDARD POSITIONING
SERVICE ON 25 MAR 90. GPS IS NOT EXPECTED TO BE DECLARED FULLY
OPERATIONAL UNTIL 1993. ANY GPS USERS ARE OPERATING AT THEIR OWN
RISK.
C. NOTICE ADVISORY INFORMATION WILL NOT BE AVAILABLE DIRECTLY FROM
THE MASTER CONTROL STATION FOR CIVIL USERS BEGINNING 1 AUG 90. THIS
INFORMATION MAY BE OBTAINED FROM THE US COAST GUARD, THE GENERAL
DYNAMICS GPS BULLETIN BOARD, AND THE US NAVAL OBSERVATORY.
D. SATELLITE REPOSITIONING:
THE SATELLITES WHICH BEGAN REPOSITIONING EARLIER THIS YEAR WILL
CONTINUE GRADUAL CHANGES TO THEIR ORBITAL POSITIONS UNTIL
REPOSITIONING TERMINATE DATES AS SHOWN BELOW:
PRN  TERMINATE#1 TERMINATE#2  REMARKS
11   31 OCT 90                FINAL MANEUV-ER
 3   17 OCT 90                FINAL MANEUVER
13    3 OCT 90                FINAL MANEUVER
18   24 NOV 90   8 DEC 90     24 NOV 90 WILL SLOW THE RATE OF CHANGE
19   31 DEC 90                FINAL MANEUVER
16   20 SEP 90                FINAL MANEUVER
 2    1 DEC 90                FINAL MANEUVER
14   10 NOV 90                FINAL MANEUVER
E. LIMITED SELECTIVE AVAILABILITY TESTING CONDUCTED DURING THE
PERIOD BEGINNING DAY 174 (24 JUN 90) UNTIL DAY 240 (28 AUG 90)
SHOULD NOT DEGRADE NAVIGATION ACCURACY BEYOND LEVELS IN EFFECT
SINCE THE IMPLEMENTATION OF THE STANDARD POSITIONING SERVICE.
HOWEVER, USERS MAY OBSERVE SOME CHANGES IN DAY-TO-DAY POSITIONING
AND NAVIGATION ACCURACY AS A RESULT OF THIS TEST. POINT OF CONTACT
IS MAJOR WYSOCKI AT USSPACECOM/SPJ3OS, (719)554-2634 OR AUTOVON
692-2634.
4. POINT OF CONTACT: MAJ FAUVER AT (719)550-6379.