`
`
`Ex. PGS 1059
`
`
`
`EX. PGS 1059
`
`
`
`
`
`

`

`United States Patent [19J
`Counselman, III
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,809,005
`Feb. 28, 1989
`
`[54] MULTI-ANTENNA GAS RECEIVER FOR
`SEISMIC SURVEY VESSELS
`
`[75]
`
`Inventor: Charles C. Counselman, III, Belmont,
`Mass.
`
`[73] Assignee: Western Atlas International, Inc.,
`Houston, Tex.
`
`[21] Appl. No.: 147,123
`
`[22] Filed:
`
`Jan. 21, 1988
`
`Related U.S. Application Data
`[63] Continuation of Ser. No. 35,662, Apr. 6, 1987, which is
`a continuation-in-part of Ser. No. 852,016, Apr. 14,
`1986, which is a continuation-in-part of Ser. No.
`353,331, Mar. 1, 1982.
`
`Int. CJ.4 ............................................. H04B 7/185
`[51]
`[52] U.S. CI ...................................... 342/352; 342/357
`[58] Field of Search ..................... 342/352, 357; 375/1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,860,921 1/1975 Wood .................................. 342/109
`3,900,873 8/1975 Bouvier et a! ...................... 342/103
`3,906,204 9/1975 Rigdon eta! ................... 342/357 X
`3,943,514 3/1976 Afendykiw eta! ................. 342/156
`4,045,796 8/1977 Kline ................................... 342/103
`4,054,879 10/1977 Wright eta! ........................ 342/192
`4,114,155 9/1978 Raab .................................... 342/394
`4,170,776 10/1979 McDoran ............................ 342/458
`4,232,389 11/1980 Loiler .................................... 455/12
`4,368,469 1/1983 Ott et a! .............................. 342/352
`4,443,799 4/1984 Rubin .................................. 375/1 X
`4,445,118 4/1984 Taylor eta!. ....................... 342/357
`4,455,651 6/1984 Baran .................................. 375/1 X
`4,463,357 7/1984 MacDoran .......................... 342/460
`4,468,793 8/1984 Johnson et a!. ..................... 342/460
`4,484,335 11/1984 Mosley eta! ........................... 375/1
`4,578,678 3/1986 Hurd ................................... 342/357
`4,601,005 7/1986 Kilvington .............................. 375/1
`4,613,864 9/1986 Hofgen ................................ 342/352
`4,613,977 9/1986 Wong eta! ..................... 324/420 X
`4,652,884 3/1987 Starker ................................ 342/357
`4,656,642 4/1987 Aposto1os eta! ....................... 375/1
`4,672,382 6/1987 Fukuhara eta! .................... 342/357
`
`FOREIGN PATENT DOCUMENTS
`852191 5/1985 Norway .
`
`OTHER PUBLICATIONS
`Charles C. Counselman III, "Radio Astrometry", An(cid:173)
`nual Reviews of Astrometry and Astrophysics, vol. 14,
`1976, pp. 197-214.
`(List continued on next page.)
`
`Primary Examiner-Theodore M. Blum
`Assistant Examiner-John B. Sotomayor
`Attorney, Agent, or Firm-Norman E. Brunell; E.
`Eugene Thigpen
`ABSTRACf
`[57]
`Method and apparatus are disclosed for accurately de(cid:173)
`termining position from GPS satellites and received on
`a ship using observations of C/ A code group delay, Ll
`band center frequency carrier phase, L1 band 5.115
`MHz implicit carrier phase, and L2 band 5.115 MHz
`implicit carrier phase. A precise measurement of the
`range to each satellite is made based upon the Ll center
`frequency carrier phase. A correction for ionospheric
`effects is determined by simultaneous observation of the
`group delays of the wide bandwidth P code modula(cid:173)
`tions in both the Ll and L2 bands. These group delays
`are determined by measuring the phases of carrier
`waves implicit in the spread-spectrum signals received
`in both bands. These carriers are reconstructed from
`both the Ll and L2 band signals from each satellite
`without using knowledge of the P code. The unknown
`biases in the Ll center frequency carrier phase range
`measurements are determined
`from simultaneous,
`pseudorange measurements, with time averaging. The
`instantaneous position of the antenna receiving these
`signals, and therefore the ship, may then be determined
`from the ranges so determined, with both the bias and
`the ionospheric effects having been eliminated. Addi(cid:173)
`tional antennas are positioned on the ship and a seismic
`streamer towed by the ship to reject false signals, com(cid:173)
`pensate for blockage of signals by the ship's structure,
`and determine the position of sensors in the streamer.
`
`9 Claims, 25 Drawing Sheets
`
`Ex. PGS 1059
`
`

`

`4,809,005
`
`Page 2
`
`OTHER PUBLICATIONS
`
`Counselman, Shapiro, Greenspan and Cox, "Backpack
`VLBI Terminal with Subcentimeter Capability",
`NASA Conference Publication 2115-Radio Interfer(cid:173)
`ometry Techniques for Geodesy, 1980, pp. 409-414.
`Counselman, Gourevitch, King, Herring, Shapiro,
`Greenspan, Rogers, Whitney and Cappallo, "Accuracy
`of Base~ine D~terminations by MITES Assessed by
`Companson w1th Tapes, Theodolite, and Geodimeter
`Measurements", EOS, The Transactions of the Ameri(cid:173)
`can Geophysical Union, vol. 62, Apr. 28, 1981, p. 260.
`Counselman and Shapiro, "Miniature Interferometer
`Terminals for Earth Surveying", Bulletin Geodesique,
`vol. 53, 1979, pp. 139-163.
`W. 0. Henry, "Some Developments in Loran", Journal
`of Geophysical Research, vol. 65, Feb. 1960, pp.
`506-513.
`Pierce, "Omega", IEEE Transactions on Aerospace
`and Electronics Systems, Vol. AES-1, No. 3, Dec.
`1965, p. 206-215.
`J. J. Spilker, Jr., "GPS Signal Structure and Perfor(cid:173)
`mance Characteristics", Navigations, vol. 25, No. 2,
`1978, pp. 121-146.
`Bossler, Goad and Bender, "Using the Global Position(cid:173)
`ing Systems (GPS) for Geodetic Positioning", Bulletin
`Geodesique, vol. 54, 1980, pp. 553-563.
`A~an E: E. Rogers, "Broad-Band Passive 90° RC Hy(cid:173)
`bnd with Low Component Sensivity for Use in the
`Video Range of Frequencies", Proceedings of the
`IEEE, vol. 59, 1971, pp. 1617-1618.
`M. L. Meeks, Editor, Methods of Experimental Physics,
`vol. 12, (A~trophysics), Part C (Radio Observations),
`1976, pp. v-1x and as follows: Chapter 5.3: J. M. Moran
`"Very Long Baseline Interferometer Systems", pp:
`174-197, Chapter 5.5: J. M. Moran, "Very Long Base(cid:173)
`line Interferometric Observations and Data Reduc(cid:173)
`tion", pp. 228-260, Chapter 5.6: I. I. Shapiro, "Estima(cid:173)
`tion of Astrometric and Geodetic Parameters", pp.
`261-276.
`Counselman and Gourevitch, "Miniature Interferome(cid:173)
`ter Terminals for Earth Surveying: Ambiguity and Mul(cid:173)
`tipath with Global Positioning Systems", IEEE Trans(cid:173)
`actions on Geoscience and Remote Sensing, vol.
`GE-19, No. 4, Oct. 1981, pp. 244-252.
`Counselman and Shapiro, "Miniature Interferometer
`
`Terminals for Earth Surveying", Proceedings of the 9th
`GEOP Conference, An International Symposium on
`the Applications of Geodesy to Geodynamics, Oct. 2-5,
`1978, Dept. of Geodetic Science Report No. 280, The
`Ohio State University, 1978, pp. 65-85.
`Peter F. MacDoran, "Satellite Emission Radio Interfer(cid:173)
`ometric Earth Surveying Series-GPS Geodetic Sys(cid:173)
`tem", Bulletin Geodesique, vol. 53, 1979, pp. 117-138.
`Peter F. MacDoran, "Series-Satellite Emission Radio
`Interferometric Earth Surveying", Third Annual
`NASA Geodynamics Program Review, Crustal Dy(cid:173)
`namics Project, Geodynamics Research, Jan. 26-29,
`1981, Goddard Space Flight Center, p. 76 (plus) Three
`View Graph Figures entitled: Satellite L-Band Iono(cid:173)
`spheric Calibration (SLIC); Series One-Way Range
`Receiver Simplified Block Diagram; and Series Re(cid:173)
`ceiver Range Synthesis.
`Peter F. MacDoran, "Satellite Emission Range Inferred
`Earth Surveying, Series-GPS", JPL, presented at
`Defense Mapping Agency Meeting, Feb. 9, 1981, 13 pp.
`MacDoran, Spitzmesser and Buennagel, "Series: Satel(cid:173)
`lite Emission Range Inferred Earth Surveying", Pres(cid:173)
`ented at the Third International Geodetic Symposium
`on Satellite Doppler Positioning, Las Cruces, N.M.,
`Feb. 1982, 23 pp.
`MacDoran, Spitzmesser and Buennagel, "Series: Satel(cid:173)
`lite Emission Range Inferred Earth Surveying", Pro(cid:173)
`ceedings of the 3rd International Geodetic Symposium
`on Satellite Doppler Positioning, vol. 2, 1982, pp.
`1143-1164.
`"Operating Manual STI Model 5010 GPS Receiver",
`Inc., STI-0 &
`Stanford Telecommunications
`M-8707B, Feb. 25, 1980, selected pages as follows: Title
`page, i-iv, 1-1, 1-3, 2-1 through 2-5, 3-1 through 3-3,
`6-1 through 6-9.
`"Pioneer Venus Project, Differenced Long-Baseline
`Interferometry Experiment, Design Review Docu(cid:173)
`ment", NASA Ames Research Center, Moffett Field,
`Calif., Jul. 1, 1977, 23 pp.
`C. Goad, "Visit with P. MacDoran, Aug. 6, 1981",
`Memo to Capt. Bossler, sent to Dr. Counselman, Aug.
`12, 1981, 3 pp.
`Peter F. MacDoran, Statements made at the 3rd Inter(cid:173)
`national Geodetic Symposium on Satellite Doppler
`Positioning, Feb. 1982.
`
`(List continued on next page.)
`
`Ex. PGS 1059
`
`

`

`4,809,005
`
`Page 3
`
`OTHER PUBLICATIONS
`
`A. E. E. Rogers, C. A. Knight, H. F. Hinteregger, A. R.
`Whitney, C. C. Counselman III, I. I. Shapiro, S. A.
`Gourevitch and T. A. Clark, "Geodesy by Radio Inter(cid:173)
`ferometry: Determination of a 1.24-km Base Line Vec(cid:173)
`tor with 5-mm Repeatability", J. Geophysics. Res., vol.
`83, pp. 325-334, 1978.
`W. E. Carter, A. E. E. Rogers, C. C. Counselman III,
`and I. I. Shapiro, "Comparison of Geodetic and Radio
`Interferometric Measurements of the Haystack-West(cid:173)
`ford Base Line Vector", J. Geophysics. Res., vol. 85,
`pp. 2685-2687, 1980.
`R. A. Preston, R. Ergas, H. F. Hinteregger, C. A.
`Knight, D. S. Robertson, I. I. Shapiro, A. R. Whitney,
`A. E. E. Rogers, and T. A. Clark, "Interferometric
`Observations of an Artificial Satellite", Science, vol.
`178, pp. 407-409, 1972.
`C. C. Counselman, III and I. l. Shapiro, "Miniature
`Interferometer Terminals for Earth Surveying", Proc.
`of the 2nd Int.'l Geodetic Symposium of Satellite Dop(cid:173)
`pler Positioning, vol. 2, pp. 1237-1286, 1979, (avail.
`from Appl. Res. Lab., University of Texas, Austin, Tex.
`78758).
`R. J. Anderle, "Application of the NAVSTAR GPS
`Geodetic Receiver to Geodsey and Geophysics", Naval
`Surface Weapons Center Tech. Rept., No. 80-282, 27,
`pp., 1980.
`J. J. Spilker, Jr., Digital Communications by Satellite,
`Prentice-Hall, Englewood Cliffs, N.J., pp. 302-303,
`1977.
`P. L. Bender, "A Proposal to the National Aeronautics
`and Space Administration for the Support of GPS Sat(cid:173)
`ellite Orbit Determination Using the Reconstructed
`Carrier Phase Method for Tracking", Quantum Physics
`Division, National Bureau of Standard, Boulder, Colo.,
`pp. l-12, submitted Aug. 5, 1980.
`Peter L. Bender, National Bureau of Standards, Private
`Communication, 1978.
`C. C. Counselman III, D. H. Steinbrecher, "The Mac(cid:173)
`rometer TM : A Compact Radio Interferometry Termi(cid:173)
`nal for Geodesy with GPS", Proceedings of the Third
`International Geodetic Symposium on Satellite Dop(cid:173)
`pler Positioning, pp. 1165-1172, Feb. 8-12, 1982.
`C. C. Counselman III, R. J. Cappallo, S. A. Gourevitch,
`R. L. Greenspan, T. A. Herring, R. W. King, A. E. E.
`Rogers, I. I. Shapiro, R. E. Snyder, D. H. Steinbrecher,
`
`and A. R. Whitnet, "Accuracy of Relative Positioning
`by Interferometry with GPS: Double-Blind Test Re(cid:173)
`sults", Proceedings of the Third International Geodetic
`Symposium on Satellite Doppler Positioning, pp.
`1173-1176, Feb. 8-12, 1982.
`R. L. Greenspan, A. Y. Ng, J. M. Przyjemski, & J.D.
`Veale, "Accuracy of Relative Positioning by Interfer(cid:173)
`ometry with Reconstructed Carrier GPS: Experimental
`Results", Proceedings of the Third International Geo(cid:173)
`detic Symposium on Satellite Doppler Positioning, pp.
`1177-1198, Feb. 8-12, 1982.
`T. P. Yunck, "An Introduction to Series-X", Jet Pro(cid:173)
`pulsion Laboratory, California Institute of Technology,
`NASA Contract NAS 7-1000, Nov. 1982.
`Buennagel, MacDoran, Neilan, Spitzmesser & Young,
`"Satellite Emission Range Inferred Earth Survey (Se(cid:173)
`ries) Project: Final Report on Research and Develop(cid:173)
`ment Phase, 1979 to 1983", JPL Publication 84 16, Mar.
`1, 1984.
`Crow, Bletzacker, Najarian, Purcell, Statman &
`Thomas, "Series-X Final Engineering Report", JPL
`D-1476, Aug. 1984.
`MacDoran, Whitcomb & Miller, "Cordless GPS Posi(cid:173)
`tioning Offers Sub-Meter Accuracy", Sea Technology,
`Oct. 1984.
`MacDoran, Miller, Buennagel & Whitcomb, "Cordless
`Systems for Positioning with Navstar-GPS", First In(cid:173)
`ternational Symposium on Precise Positioning with the
`Global
`Positioning
`System,
`Positioning with
`GPS-1985, Apr. 15-19, 1985.
`James Collins, "GPS Surveying Techniques", ACSM
`Bulletin, Jun. 1985, pp. 17-20.
`Ron L. Hatch, "The Synergism of GPS Code and Car(cid:173)
`rier Measurements", Proceedings of the Third Interna(cid:173)
`tional Geodetic Symposium on Satellite Doppler Posi(cid:173)
`tioning, pp. 1213-1231, Feb. 8-12, 1982.
`"Proposal for a GPS Geodetic Receiver", The Johns
`Hopkins University Applied Physics Laboratory, Apr.
`1980.
`Phil Ward, "An Advanced Navstar GPS Geodetic
`Receiver", Proceedings of the Third International Geo(cid:173)
`detic Symposium on Satellite Doppler Positioning, pp.
`1213-1231, Feb. 8-12, 1982.
`Javad Ashjaee, "GPS Doppler Processing for Precise
`Positioning in Dynamic Applications", IEEE Oceans
`'85, Nov. 1985.
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 1 of25
`
`4,809,005
`
`C) --
`
`' "
`'<
`
`'
`
`C\j
`
`' ' ' ' '
`
`C)
`C\j
`
`co --
`
`--C\j
`
`---
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 2 of25
`
`4,809,005
`
`TENN~ V52
`
`AN
`
`RMINAL
`
`23
`I
`
`--
`
`--
`
`--
`
`--
`
`TRACKING CHANNEL
`(ONE PER SATELLITE)
`
`UJJ
`/~ \2
`42
`38
`v
`v
`MEAS1 TS
`~~
`
`ESTIMATES
`
`41-
`
`COMPUTER
`
`t
`I
`34
`
`44 i''
`
`---4 0
`
`,..._
`52
`
`--~
`
`LOW-FREQ.. \
`SIGNALS
`l
`30
`
`v
`
`./
`
`RECEIVER
`
`j4
`
`26~
`
`4f0
`
`FREQUENCY
`STANDARD
`
`___.,
`
`CLOCK
`
`)8
`
`j6
`
`EXTERNAL
`I
`SATELLITE
`ORBIT AND
`CLOCK
`INFO.
`
`INFORMATION INPUT_( .-
`I
`54
`I
`PHASE AND
`SHIP
`DELAY
`POSITION
`OBS'NS
`AND
`FROM
`VEL. INFO.
`SHORE
`ST'NS
`
`DATA
`STORAGE
`
`POSITION
`DISPLAY
`
`I
`
`I
`48
`
`I
`50
`
`I
`56
`
`I
`53
`
`FIG. 2
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 3 of25
`
`4,809,005
`
`62
`
`DUAL
`BANDPASS
`FILTERS
`
`--~
`
`64
`
`66
`
`I
`
`--l
`
`72
`Ll
`
`74
`
`76
`
`RF TO VIDEO
`FREQUENCY
`DOWN-CO NV.
`
`L2
`
`DIPLEX
`FILTER
`
`80
`
`RF TO VIDEO
`FREQUENCY
`DOWN-CONV.
`
`1
`
`94
`
`26
`
`26
`
`! +o CARRIER
`RECONSTR.
`
`1
`
`+0 CARRIER
`RECONSTR
`
`4.f0 FROM
`FREQ. STD.
`28
`
`l_ ~:=N~--_9_6_8~6- -~:=N~ __j
`
`90
`
`88 84
`
`82
`
`100
`
`98
`
`TO 208
`
`TO 206
`
`LOW FREQUENCY __7'--:;.-----------.v
`SIGNALS 30
`TO ALL TRACKING CHANNELS 32
`(ONE PER SATELLITE)
`
`FIG. 3
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 4 of25
`
`4,809,005
`
`L I BAND
`RF SIG's FROM
`Dl PLEX FILTER 72
`
`74
`
`------~
`
`I
`I
`
`110
`
`112
`
`LOW PASS
`
`FILTER
`
`130
`
`LOW PASS
`
`FILTER__j
`
`i
`124 ___j
`
`82
`84
`/"- - - - - - - - ' ....... \
`· V G
`VI
`;
`'- __________ ,..,.
`
`TO 86 AND /90
`
`4+0 FROM
`FREQ. STD. 28
`
`26
`
`FREG.. MULT.
`X 77
`
`I 16
`
`i 308 f 0
`
`114
`
`90°
`PHASE
`LAG
`
`118
`
`I
`I
`
`I DOWN =~N_v_E_R_T_E_R __ ~ __
`
`76
`COMPLEX VIDEO SIGNAL V /
`REPRESENTED BY PHASOR
`83
`
`FIG. 4
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 5 of25
`
`4,809,005
`
`4-to FROM
`FREQ. STD.
`2.8
`
`FROM
`DOWN CONV'R 76
`
`v~
`"'
`
`2.6
`
`84
`
`82.
`
`~---- ----~ROADBAND VIDEO
`I
`
`QUADR. HYBRID
`
`140
`
`LSB
`
`USB
`
`144
`
`FILTER
`
`148
`
`146
`
`/62.
`
`L.._~ _
`
`/52.
`__;(CF =-Z+o)
`
`/56
`
`-;-z
`
`90°
`PHASE
`LAG
`
`172.
`
`I
`1 Ll BAND -to CARRIER
`RECONSTRUCTOR AND
`DOWN CONVERTE_R ___ L--~~~----- ___ _
`
`I kHz
`LPF
`
`I kHz
`LPF
`
`_j
`
`90
`
`88
`
`SG (L 1)
`COMPLEX Ll BAND
`Sr (LI)
`RECONSTRUCTED
`+0 CARRIER COMPOSITE S ____ ........_ ___ - -v - - - - - - - "
`REPRESENTED BY PHASOR
`TO 2.06
`89
`
`FIG. 5
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 6 of25
`
`4,809,005
`
`MEASUREMENTS
`
`32
`( !90 -l
`I l4to
`308 fo CARRIER PHASE AND
`!r84
`C/A CODE DELAY ERROR
`I r26 DETECTOR
`I 34
`I
`
`Vr
`
`FROM}
`76
`
`VQ
`OM 28.
`4f0 FR
`t FROM 36
`
`--
`--
`SATELLITE TRACKING CHANNEL
`(82
`
`I ~--
`I
`I
`
`~
`192--..
`
`/94 ........
`
`y
`
`\ ERROR SIGNALS,
`PHASE DELAY
`198- 2oo-..
`'
`
`PHiest TAUest
`
`PHASE AND GROUP DELAY
`REGISTER SUBSYSTEM
`
`....
`
`1\
`
`SAT.
`ASSIGN .
`41,
`FROM}
`40
`>ESTIMATES.)
`v
`
`is
`
`SIG.>THRESH.
`
`SIG. ENERGY
`
`I L348
`
`SIGN
`i
`I
`I
`
`'-201
`
`\...198
`
`tl
`
`PHASE
`AND DELAY
`MEAS'TS
`I v
`202
`
`fo CARRIER
`PHASE EST.
`
`204"'
`
`I
`I
`
`I
`
`I
`'
`
`I
`
`88
`\
`
`90
`\
`
`~ Ll BAND
`fo CARRIER
`....
`PHASE
`DETECTOR
`....
`
`I
`/96
`
`I
`I
`
`I
`L I fo RESIDUAL
`PHASE MEAS'T
`
`~
`
`i'--206
`
`v
`
`I
`210
`
`I
`I
`I
`
`s1(L1)
`
`FROM}
`86
`SQ(L 1)
`
`s 1(L2)
`FROM}
`96
`SQ(L2)
`
`204.....,
`
`98\
`
`100
`.\
`
`I
`I
`
`I
`
`fo CARRIER
`PHASE
`DETECTOR
`
`---- L2 BAND
`L_ __ _ __ j
`
`L2 fo RESIDUAL
`PHASE MEAS'T
`
`r--208
`
`1\
`
`I v
`212
`
`FIG. 6
`
`42
`
`TO
`COMPUTER
`40
`
`J
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 7 of25
`
`4,809,005
`
`308 fo CARRIER PHASE
`AND C/A CODE DELAY
`ERROR DETECTOR
`
`UNWOUND COMPLEX
`VIDEO SIGNAL U
`REPRESENTED BY \
`PHASOR 223
`
`226
`I
`CORRELATOR
`
`PHASOR
`COUNTER-
`ROTATOR
`
`I
`I
`
`6
`F R E Q. S T D. ___c_---.J.._ _
`
`_____,
`
`28
`t FROM
`CLOCK
`
`:
`
`4fo FROM 121
`I
`3 4
`)
`I 4,1
`I
`
`36
`SAT. ASSIGN'-. --'-----1
`FROM 40
`
`I
`I
`
`L
`
`DELAY ERR.SIG. }TO
`
`2bo I~ 196
`PHASE ERR.
`SIG. L/98
`
`TO
`40
`
`SIG.>THRESH.
`
`SIGN BIT
`
`4~0 1
`/o;
`I
`SIGNAL ENERGY
`
`3~8
`
`228-.... 230
`I
`
`222
`I
`224
`l
`-220
`
`I u I \
`(
`)'
`,UQ/
`
`25
`)
`
`26
`
`/--.. X2
`
`Bfo
`
`27-...__
`34
`I
`
`41
`I
`
`!"- 308 fo CARRIER
`PHASE ESTIMATE
`PHI est 192
`
`C/A CODE GROUP
`DELAY ESTIMATE...--_
`!94
`TAUest
`----------------·---
`
`I
`I
`
`___ j
`
`FROM PHASE
`REGISTER
`840
`
`FROM DELAY
`REGISTER
`842
`
`FIG. 7
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 8 of25
`
`4,809,005
`
`VG
`
`1st
`QUADRANT
`
`2nd
`QUADRANT
`87
`
`ANGLE 8/, THETA
`Vr
`
`3 rd
`QUADRANT
`
`4th
`QUADRANT
`
`3 rd
`QUADRANT
`
`FIG.
`
`8A
`
`FIG. 88
`
`1st
`QUADRANT
`
`PHiest,/92
`
`85
`
`4th
`QUADRANT
`
`2nd
`QUADRANT
`87
`
`1st
`QUADRANT
`
`(THETA-PH I est)
`
`3rd
`QUADRANT
`
`85
`
`4th
`QUADRANT
`
`FIG.
`
`Be
`
`SG
`
`87
`
`sr
`
`85
`
`FIG. 80
`
`--.. i4---- DELAY ERROR WHOSE SIGN
`IS INDICATED BY ERROR
`SIGNAL 200
`
`SATELLITE CLOCK
`INDICATION tj ,60lf------l/
`
`L...__ ___ ___,t- TAU e s t , 876
`
`FIG. BE
`
`REAL TIME
`INDICATION, 34
`
`TIME OR DELAY
`
`TAU
`
`....
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 9 of25
`
`4,809,005
`
`COMPLEX VIDEO
`SIGNAL V
`REPRESENTED
`BY PHASOR 83
`
`1 } ""-
`
`FROM
`76
`
`/ v -" ------<~
`I
`I
`I
`I
`I
`I
`'Vo-~~
`'-_/
`
`LOGIC
`
`812
`
`814
`
`---..
`308 fo CARRIER
`1 R
`PHASE ESTIMATE
`PHiest 192--:_~\ I
`'
`
`/
`
`---
`
`'
`
`FROM PHASE REGISTER 840
`
`FIG. 9A
`
`/~,'':}~~6
`1----'------1~ U G I
`"
`
`/
`\_ UNWOUND COMPLEX
`VIDEO SIGNAL U
`REPRESENTED BY
`PHASOR 223
`
`PHASOR
`QUADRANT
`
`1st
`
`2nd
`3 rd
`4th
`
`2- BIT DIGITAL
`REPRESENTATION
`
`SIGN
`
`BINARY
`
`806
`
`808
`
`812
`
`814
`
`I
`
`0
`
`0
`I
`
`I
`I
`
`0
`0
`
`0
`0
`
`I
`I
`
`0
`I
`
`0
`I
`
`FIG. 98
`
`LOGIC OUTPUT ur
`
`(222)
`
`5814
`= 00
`806,808
`=00
`
`0
`
`01
`
`II
`
`I
`
`I
`
`10
`
`0
`
`01
`
`II
`
`10
`
`I
`
`I
`
`0
`
`0
`
`0
`
`0
`
`I
`
`I
`
`I
`
`0
`
`0
`
`I
`
`FIG. 9C
`
`LOGIC OUTPUT U0 (224)
`1~814 = 00
`806,808
`= 00
`
`01
`
`I
`
`II
`
`0
`
`I
`
`01
`
`I I
`
`10
`
`I
`
`0
`
`0
`
`0
`
`0
`
`I
`
`I
`
`I
`
`0
`
`I
`
`FIG. 90
`
`10
`
`0
`
`0
`
`I
`
`I
`
`Ex. PGS 1059
`
`

`

`358
`
`356
`
`198
`
`I
`I
`
`I
`
`TO
`196
`
`~
`r.J1
`•
`
`~ a
`n> a
`
`~
`~
`N
`'"010
`~
`\C
`010
`\C
`
`I
`8fo ~ FROM
`
`I
`I
`
`25
`
`34
`
`t
`FROM
`36
`
`I
`I
`
`228
`
`FROM
`230
`}
`
`FIG 10
`
`TO
`196
`
`gJ
`(t)
`~
`~
`
`N
`til
`
`0 a
`...
`
`....
`00
`0
`\C
`....
`Q
`0
`Ul
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28,1989
`
`Sheet 11 of 25
`
`4,809,005
`
`2301
`
`~--_L _________ __ __ __ _ __ _ __ _ __ _
`
`TO CORRELATOR 226
`
`ONE -BIT
`CIA CODE _
`LOCAL
`MODEL 228
`
`- - - - - -
`
`•
`\
`I
`
`CODE
`MEMORY
`
`450~~------~~-~
`
`~_/ r
`
`ADDRESS-
`460
`
`I
`
`CIA CODE GENERATOR
`
`FROM
`COMPUTER
`40
`
`)
`
`SATELLITE ASSIGNMENT
`
`SETTABLE
`MODULO- 40
`COUNTER
`
`>--.---/--1-..lJ NC R
`27
`
`fo/5
`0 v f----....::...._....---1~
`45~
`
`I NCR
`
`SETTABLE
`MODULO -I 023
`COUNTER
`
`I
`I
`
`8 fo
`FROM 25
`
`FROM 36
`
`ENBL VALUE TO SET
`SET
`
`---
`
`f-.---
`
`ENBL
`
`SET •
`
`4~6
`--
`
`VALUE TO SET
`'---,..
`/
`
`WHOLE
`CHIPS
`
`4oTHSoF
`10 THS OF
`A CHIP
`(!OBITS) v
`A CHIP
`---+{4 BITS)
`(2 BITS)-V
`CIA CODE
`------------- -----
`_-
`GROUP DELAY
`EST I MATE !94 ~=~C!_4-"
`~'--872
`874_./ ---
`--- ---------------------------
`
`FROM 864 FROM 866
`
`L..-----.._
`FROM 868
`
`FROM DELAY REGISTER 842
`
`FIG. I I
`
`Ex. PGS 1059
`
`

`

`Ll BAND fo CARRIER
`PHASE DETECTOR
`
`"UNWOUND"
`240
`SIGNALS
`,-------"----~ 24 4
`
`248
`,------'----~
`INTEGRATOR
`(100 sec)
`
`Ll fo RESIDUAL PHASE
`MEASUREMENT 210
`
`FROM 86
`
`PHASOR
`COUNTER-
`ROTATOR
`
`90
`
`S~-_L---.1 L:
`
`250
`
`TO 40
`
`fo CARRIER PHASE
`ESTIMATE __ 2_0_4 ________ _
`
`FROM 196
`
`FIG. 12
`
`Ex. PGS 1059
`
`

`

`FIG. !3A
`
`INITIAL VALUE
`~ AIDING FROM
`COMPUTER 40
`
`)
`
`r
`
`/96]
`
`~-;:l
`__;__ __ cz 34
`..,.,.J---"C--=L=-=O'-=-C_:_:K--"~'-"6 _
`TO ADDERS I
`
`898 TO 908
`
`I
`
`I
`900
`
`~J 906 r-----'-~--'------,
`:3q
`1 {" FREQUENCY 1·) • CARRIER FREQUENCY 1 - - - - - - - - - - - - - - - - ' -~"\
`~\(PHASE-INCREMENT,
`ADDER
`. f I \908
`(100/SEC) ---,/ OR RATE) REGISTER
`\. 902
`I
`900-l
`r - - - - -~"'"'7:.__8:.._9_::8_?-j~
`(852
`__ __ J L....._----"-'\ PHASE A ODE R
`VfL__.L__--,
`1\------
`( 110,000/ SEC)
`
`1
`. , - -
`
`)
`
`/98 ~
`
`r
`
`894 r
`
`I
`
`II
`
`308 f0 CARRIER
`PHASE ERROR
`SIGNAL FROM
`tan-1 (Q/ 1), 334
`
`192
`
`308 f 0 CARRIER
`PHASE ESTIMATE
`TO Ll VIDEO
`{
`COUNTER-ROTATOR
`220
`DELAY ERR.
`SIG. FROM
`CORR 226
`
`l' 1 4 18\
`. ~2~u 414 J
`
`I
`
`3: ..../
`PHASE
`>- ~
`REGISTER,
`I MS 8 ~ LOWER PART
`~<(
`0:0 814 I
`..... -~---'-----'-( I_/_4_C_Y_._A_T_3_0_8_fo=--')'--_u"'l'-m-'T'--'-l---,-: __ _,l
`B48
`I
`( 1/2 CY. AT 308 fo)
`J
`I
`8)2 I
`
`896 ~Jg~:~RIER---- ~852
`
`}
`16BITS
`:
`\344 1
`
`·~
`
`856
`I "
`48 BITS
`v
`
`A
`
`¢
`
`~
`
`~ PHASE RE:I:_:_:_P_A...,.RT- ~ 1854
`
`202
`
`880_,..--
`
`892
`878 r
`
`890
`
`1.
`840
`
`I
`850,
`\L_ .!:_~8- _
`CARRIER
`I
`.---~'IC-..__-7-1 -ll'l DECR PHASE
`1-3-2'--B-I-'TS
`/
`t-------...,--...! INCH
`REGISTER,
`>-------,---.....J'I'---'"1'---,
`
`Ex. PGS 1059
`
`

`

`202
`
`876
`I
`
`30 BITS
`
`Av
`
`t
`
`I
`I
`
`1
`
`I
`
`LBITS[~ I
`888 .;- 1023 : .;- lifj '
`
`--
`r860
`
`l
`
`~
`TJ)_
`•
`~
`""""""" g
`
`"""""""
`
`~ ?-
`
`N
`~
`~
`\C
`00
`\C
`
`(7 BITS) ~
`870
`
`, .
`
`---
`
`4
`
`-
`
`-
`
`I
`37
`
`(
`
`INITIAL VALUE
`~
`FROM COMPUTER ~
`40
`
`a
`
`N
`(Ja
`
`880 ~878
`
`~ 7 BITS I r858 ----16 BITS
`
`I
`I
`
`I
`
`8
`
`42-
`
`DELAY REGISTER
`--
`
`--
`
`196)
`
`I
`864
`- - - - - -
`---- - - --
`--
`1/4 CY. BIT~
`1/2 CY.
`BIT..--
`
`DUL0-'77
`MODUL0-40
`MODUL0-130944
`V'BLE CNTR 882 REVERSIBLE COUNTER 886 REVERSIBLIE COUNTER
`I
`I
`I
`INCR
`o'FLO
`o'FLO
`I NCR
`INCR
`I
`I
`884 74 I 7 10
`77
`,
`I
`I
`u'FLO
`DECR
`U FLO
`DECR
`DECR
`I
`1
`(7 BITS)
`(2 BITS) I
`(10 BITS) I
`(4 BITS)
`7
`\
`866 868
`---
`
`1---872 874~
`v
`
`!;;>-
`
`,
`10 THS OF
`WHOLE
`A CHIP
`CHIPS
`204~~---------~,r--------~
`!94
`TO C/A CODE GEN. 230
`f 0 CARRIER
`TO
`PHASE DET'S
`206 $ 208
`
`FIG. 138
`
`Ex. PGS 1059
`
`

`

`ANTENNA
`
`22
`. - - - - - - - - - - - - - -
`
`FIG. 14A
`
`32)- --6~2-r~-=-=_6_5_0_-IXI~
`
`I
`
`610
`
`6 4 8 ,--___L_____j
`
`600
`
`606
`
`726
`
`616
`~---
`____J.__:;'63 6
`~ _
`~616 CIA CODE GEN.
`,----L~ I PHASE FEEDBACK
`628
`1-
`
`____L _
`
`684
`FROM
`40
`
`670
`
`I DELAY
`PHASE
`626
`742
`NUMBER
`L-------'1~---------------------~---------L~--~~
`
`I
`1 CODE DELAY
`
`698 I MEASUREMENT
`
`Ex. PGS 1059
`
`

`

`742
`
`751
`
`I
`I
`
`CODELESS DUAL BANDl
`f 0 PHASE DETECTOR
`
`1 ~32
`
`740
`
`L_~----~758 L_______J
`
`760
`
`23
`
`L I fo
`f-------=---tl~ RESIDUAL
`PHASE 7/8
`
`I
`I
`
`ARCTAN
`
`762
`
`I 1
`___ A_R_C_~-A-N - 1------,-~~ ~~~~~~A7~0
`
`L2
`
`f 0
`
`FIG. 148
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 17 of 25
`
`4,809,005
`
`70/
`
`I OBSERVABLES COMBINER-
`-
`922')
`SCALE
`CONY.
`
`I
`
`876]
`TAU OR
`698
`
`\..920
`
`924~
`
`SCALE
`CONV.
`
`926")
`
`PHI
`
`856]
`OR
`626
`
`I
`
`I
`
`t _r936
`(-)
`6
`(+)
`
`938?
`
`940~
`
`TIME
`AVG.
`
`I
`I
`
`I
`
`I
`I
`I
`
`928'\
`
`SCALE
`CONV.
`
`932\
`
`930\
`
`t
`(+)
`6
`(-)
`
`I
`
`SCALE
`
`934..,
`
`•
`
`'948
`
`CONV. L __ _
`I OBSERVABLES COMBINER --ll-701
`
`PSI 2/0l OR
`
`(L I) 718
`
`PSI
`
`2 12]
`(L2) 7~~
`
`876]
`TAU OR
`698
`
`l=_942
`[,r944
`(
`
`(-)
`(+) 6
`
`926\
`
`X 3600
`2329 !'--
`
`l:_
`
`956
`954
`
`I
`I
`
`946
`t ?60
`(+)
`6
`( -)
`4
`\_958
`
`VACUUM
`RANGE
`962
`
`I
`950
`
`TIME
`AVG.
`
`[\._952
`
`I
`I
`
`856]
`PHI OR-~
`626
`
`KALMAN
`FILTER
`
`210
`]
`PSI
`(Li) 7~~ -~
`2 12]
`(L2) 7~~ -~-:_j-.-----r---J
`763
`
`PSI
`
`EXT. INFO 707
`
`--
`
`FIG. 15A
`
`POSIT! ON
`INFORMATION
`705
`
`FIG. 15 B
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 18 of 25
`
`4,809,005
`
`KALMAM FILTER PARAMETERS
`
`STATE VARIABLE
`
`SIGMA
`
`CORRELATION TIME T
`
`ZERO
`LATITUDE (LAT.)
`[LATITUDE IS GIVEN EXACTLY BY THE INTEGRAL OF D(LAT) / DT.]
`
`--
`ZERO
`LONGITUDE (LON.)
`[LONGITUDE IS GIVEN EXACTLY BY THE INTEGRAL OF D (LON)/DT.]
`
`HEIGHT (HGT.)
`
`I 0 METERS
`
`I o4 SECONDS
`
`D (LAT.)/DT
`
`3 METERS /SEC
`
`I o4 SECONDS
`
`D (LON.)/ DT
`
`3 METERS/ SEC
`
`I o4 SECONDS
`
`DELTA LAT.
`
`5 METERS
`
`4 SECONDS
`
`DELTA LON.
`
`5 METERS
`
`4 SECONDS
`
`DELTA HGT.
`
`5 METERS
`
`4 SECONDS
`
`CLOCK EPOCH
`
`7X 10-6 SEC
`
`10 12 SECONDS
`
`CLOCK RATE
`
`7 X I o-9 SEC/ SEC
`
`I 012 SECONDS
`
`[THE EPOCH ERROR OF THE CLOCK IS GIVEN BY THE SUM OF THE "CLOCK
`EPOCH"PROCESS AND THE INTEGRAL OF THE "CLOCK RATE" PROCESS
`CHARACTERIZED ABOVE.]
`
`PH I BIAS (EACH SAT.)
`
`20 CENTIMETERS
`
`I o8 SECONDS
`
`IONOSPHERE AT L I
`
`I 0 METERS
`
`6 X I o4 SECONDS
`
`FIG.
`
`!5C
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 19 of 25
`
`4,809,005
`
`GPS
`SATELLITE
`
`GPS
`SATELLITE
`
`Q
`GPS-2-/~
`/
`\
`
`GPS-1-~'
`' , , //\~,
`I
`' , ~1575MHZ .
`/
`SIGNALS
`I
`/
`'
`I
`----!
`/ / / . --__::::__...,..., '>
`
`//.:,...,
`
`\
`\
`\
`\ - - -
`
`lOll
`
`1013-1
`
`1013-2
`
`I
`
`ERFEROMETER
`LD
`TERMINAL
`+"'-
`SURVEY~ \
`MARK
`-
`\
`SM-1
`
`•
`
`\
`
`\
`
`\
`
`\
`
`:TERFEROMETER
`FIELD
`TERMINAL
`. . . - ! I
`I
`BASELINE VECTOR b
`I -!.{SURVEY
`I
`I
`-
`MARK
`I
`SM-2
`
`\
`
`I
`I
`
`I
`
`.
`
`I
`
`'\'-,~~ COMPU;ER r_.//
`1015 ~ /1019
`
`/
`!017\
`~-~---
`FIRST DATA
`STORE
`
`~----~-----
`SECOND DATA
`STORE
`
`FIG. /6
`
`Ex. PGS 1059
`
`

`

`I AN;"' ASSEMBLY
`
`ANTENNA
`
`1
`I
`
`PREAMPLIFIER
`CIRCUIT
`
`FIG. 17
`
`SIDEBAND
`SEPARATOR
`
`u ( t)
`
`I ( t)
`
`5.115MHZ
`
`DIGITAL
`ELECTRONICS
`UNIT
`
`I
`1035
`
`RECEIVER UNIT, 1031
`
`I
`
`/
`1023/
`
`INTERFEROMETER
`FIELD TERMINAL, 1013
`
`FIELD
`TERMINAL
`COMPUTER
`
`1039
`
`ELECTRONICS
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 21 of 25
`
`4,809,005
`
`1027
`
`~ANTENNA ASSEMBLY 102/
`
`COAX lA L
`CABLE
`CONNECTOR
`
`I
`I
`
`REG~
`F/G./8
`
`105!
`
`-
`
`1029
`
`.
`
`I (t)
`
`--l !E~6:WR --~
`
`I
`
`SUPS
`
`I
`
`I
`
`-
`
`I
`~ I
`
`RECEIVER POWER
`CIRCUIT, /034
`
`I
`
`1~5
`
`1---'-- 5.115 MHZ
`TO DIGITAL
`ELECTRONICS
`ASSEMBLY
`UNIT
`
`--- 1575.42
`
`MHZ
`
`SIDEBAND SEPARATOR, /033
`
`--
`
`lr
`
`:
`
`~----- td7t--- 107_9/o8fj
`I
`I
`I
`I
`I
`
`BPF
`
`LIM
`
`1043
`
`1045
`
`PREAMPLIFIER CIRCUIT
`-
`
`1059
`
`DC
`
`1099
`
`vco
`
`X4
`
`I
`I
`I
`/0731 1067
`I./
`r
`I
`I
`I
`
`1
`
`I
`I
`I
`
`5.115MHZ-
`
`Gs75.42MHZ SYNTHESIZER
`----------------
`OSCILLATOR CIRCUIT, /035
`
`Jl
`
`1057
`
`FIG. 19
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 22 of 25
`
`4,809,005
`
`U ( t) ...:::!:.cP:::::.._ __ .[S:-;-:1 G~N:-;-A:-L -~
`I (t)--.::1=>------.!CONDITIONER
`5.115 MHZ --.;P-----t_----r _ _jf-----..---.1
`1/25
`
`-9:r
`10.23
`MHZ
`
`CORRELATOR
`ASSEMBLY
`
`. - - DIG I TAL ELECTRONICS
`UN IT, 1037
`1127
`
`1133
`
`TO FIELD
`TERMINAL
`COMPUTER
`1039
`
`F!G.20
`
`REAL
`TIME
`CLOCK
`
`NUMERICAL
`OSCILLATOR
`ASSEMBLY
`
`I 131
`
`1129
`
`EXTIPPS
`INPUT
`
`IPPS
`OUTPUT
`
`ANALOG
`u ( t)
`
`ANALOG
`I ( t)
`
`...-siGNAL coNDITIONER, 125
`
`FF
`
`U~H
`TTL LEVELS
`
`I I 4 I .---------,..-L----,1 I 4 3
`
`=r 1-----+----- TTL LEVELS
`
`}----
`
`10.23 MHZ
`
`SINUSOIDAL
`5.115 MHZ
`
`.--X-2..J-,
`
`FIG. 2/
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb.28, 1989
`
`Sheet 23 of 25
`
`4,809,005
`
`U 3 L ---:----.,---4
`co s --'--1----1
`
`1153
`
`1159
`
`COUNTER
`
`CLK
`
`SIN
`
`CLK
`10.23 MHZ_~~ - - - - - - - - - - - '
`"CLOCK"
`I
`I
`IPPS
`I ~~~~-·
`.CLOCK
`~~~OR MODULE
`
`LATCH
`RESET
`
`FIG 22
`
`1173
`
`10.23
`MHZ
`CLOCK
`
`IPPS
`RESET
`
`FIG. 23
`
`TO
`DATA
`BUS,
`1/33
`
`TO
`DATA
`BUS,
`1/33
`
`1163
`
`FROM
`DATA
`BUS,
`//33
`
`Ex. PGS 1059
`
`

`

`1/8/
`
`/183
`
`1!85
`
`1187
`
`!189
`
`CPU
`
`PROGRAM
`MEMORY
`
`DATA
`MEMORY
`
`EXTERNAL
`DATA PORT
`
`OPERATOR
`TERMINAL
`
`DATA BUS
`
`TO REAL TIME CLOCK, 1/31
`NUM. OSC. ASS'Y,//29
`AND CORR. ASS'Y,//27
`
`FIELD TERMINAL
`COMPUTER
`/039
`
`EXTERNAL
`DATA PORT
`
`MODEM
`
`/191
`
`FIG. 24
`
`1195
`
`TELECOMM.
`LINK
`
`Ex. PGS 1059
`
`

`

`U.S. Patent
`
`Feb. 28, 1989
`
`Sheet 25 of 25
`
`4,809,005
`
`~O<t_
`~18
`
`1216
`
`\
`
`1
`
`!206
`
`\
`\
`
`\
`\
`\
`\
`I
`\
`\
`12!6--'
`\
`\
`\
`I
`\
`\
`\
`\
`\
`I
`\
`\
`
`1214
`
`FIG. 25
`
`Ex. PGS 1059
`
`

`

`1
`
`4,809,005
`
`MULTI-ANTENNA GAS RECEIVER FOR SEISMIC
`SURVEY VESSELS
`
`2
`tial navigation systems to navigate the ship and deter(cid:173)
`mine the position thereof, but the information deter(cid:173)
`mined concerning the position and shape of the
`streamer during the survey is often quite limited. Many
`5 times the information available concerning the actual
`position of the streamer during the survey is limited to
`an observation that a visually identifiable flag flown
`from a tail buoy dragged by the streamer indicates that
`10 the streamer is being towed directly behind the ship.
`Such indications are useful for determining that the
`streamer has recovered from the effects a major change
`in ship direction, such as a 180• turn, so that recording
`of survey information can continue. These indications,
`however, are not usually sufficient to permit complete
`use of the more sophisticated forms of seismic surveys
`presently being developed, some of which are called
`3-D surveys.
`For these more sophisticated forms of seismic survey
`work, it is desirable to know the exact location of the
`streamer, and its sensors, during the survey so that in(cid:173)
`formation collected during one part of the survey at a
`particular location may be used to improve or interpret
`information collected at a different location during
`another part of the survey or even during another sur(cid:173)
`vey. In order to utilize such information it is necessary
`to know very accurately the position of the sensors
`detecting the information at the time of the detection.
`
`BACKGROUND OF THE INVENTION
`This is a continuation of co-pending application Ser.
`No. 035,662, filed on Apr. 6, 1987, which is a continua(cid:173)
`tion-in-part of U.S. patent application Ser. No. 852,016
`filed on Apr. 14, 1986 in the name of Charles C. Coun(cid:173)
`selman III, which itself is a continuation-in-part of U.S.
`patent application Ser. No. 353,331 filed on Mar. 1,
`1982, also filed in the name of Charles C. Counselman
`III.
`The present invention relates generally to an im(cid:173)
`proved method and system for measuring position on 15
`earth from a moving platform, such as a ship, using
`signals from the NA VST AR Global Positioning Sys(cid:173)
`tem satellites, commonly called GPS satellites. In par(cid:173)
`ticular, the present invention relates to civilian GPS
`receivers, that is, receivers which do not utilize knowl- 20
`edge of the potentially unavailable P code component
`of the GPS signals to determine position information.
`Conventional civilian GPS receivers utilize simulta(cid:173)
`neous pseudorange, in other words, group delay obser(cid:173)
`vations of the C/ A code components of the Ll band 25
`signals received from a plurality of GPS satellites to
`determine position information. A major source of posi(cid:173)
`tion errors with such conventional GPS receivers is
`multipath. Multipath errors may be reduced by time
`averaging of observations made from a fixed position. 30
`Conventional time averaging, however, cannot be used
`to improve the accuracy of receivers on ships because
`the resultant position information would relate to the
`average position of the ship during the observation
`period, not the instantaneous position.
`Position errors also result from ionospheric group
`delay effects in such pseudorange measurements. The
`magnitude of the delay encountered by a signal in the
`ionosphere varies with local conditions and cannot be
`predicted with sufficient accuracy to be eliminated from 40
`position measurements made by GPS receivers. The
`magnitudes of such errors are frequency dependent,
`however, and can be determined from simultaneous
`measurements of signals in different frequency bands. In
`particular, the GPS system was designed so that simul- 45
`taneous measurement of signals in the Ll and L2 bands
`could be used to determine ionospheric delay. This
`technique is routinely used in military GPS receivers.
`Conventional civilian receivers measure the C/ A code
`group delay in the Ll band, but cannot make L2 band 50
`C! A code group delay measurements because the C/ A
`code modulation is not presently applied to signals
`transmitted in the L2 band. Simultaneous