GISM user manual 6.53-bis
Contents
1. 25 6 4 MAS M 26 7 Comparison with measurements sua u kaw na n ava QG u a an e 27 www ieea fr IEEA Bs EE Ae TEE NTIS as A A E ned REAA EEAS 29 SLi SCOMALIOS RM LED 29 8 2 Simulation assuming static user and satellite constellation 29 8 3 Simulation assuming static user and static satellite point to point link 30 S A Static user trajettory RR 30 S S MAPS ii C e 31 9 Migrating from previous version to GISM version 6 53 32 PIN Referentes sa arani E kie 33 www ieea fr 4 GISM user manual v6 53 IEEA on 1 Introduction As a result of propagation through ionosphere electron density irregularities transionospheric radio signals may experience amplitude and phase fluctuations In equatorial regions these signal fluctuations specially occur during equinoxes after sunset and last a few hours They are more intense in periods of high solar activity These fluctuations result in signal degradation from VHF up to C band They are a major issue for many systems including Global Navigation2. PP ren emi der T EEFE ETET EE EEE me XR gh gh 9 ok GF oe gi Ge A AO AN AE AD Ah AD AO AT AB AD ae yo Smoothed Monthly Values Monthly Values Predicted Values Smoothed Updated 2010 Mar 4 NOAA SWPC Boulder CO USA Figure 4 Solar Spot Number Drift velocity The apparent drift velocity at receiver level is a combination of ionosphere drift velocity and motion of the link ionosphere pierce point IPP The IPP motion modifies the fades duration It can be an increase or a decrease depending on the geometry It also depends on the magnetic field as a result of elongated bubbles in that direction 4 5 The IPP drift velocity default value is set to 100 m s at low latitudes and to 1000 m s at high latitudes www ieea fr 23 GISM user manual v6 53 IEEA o 5 3 Nequick model NeQuick 2 used in GISM is the latest version of the NeQuick ionosphere electron density model developed at the Aeronomy and Radiopropagation Laboratory of the Abdus Salam International Centre for Theoretical Physics ICTP Trieste Italy with the collaboration of the Institute for Geophysics Astrophysics and Meteorology of the University of Graz Austria 6 The NeQuick is a quick run ionospheric electron density model particularly designed for transionospheric propagation applications To describe the electron density of the ionosphere above 100 km and up to the peak of the
3. flux_number 150 0 receiver MarakParak 60011600 0 0 time s 600 0000 1200 000 1800 000 2400 000 3000 000 3600 000 4200 000 4800 000 5400 000 6000 000 6600 000 7200 000 7800 000 8400 000 9000 000 9600 000 10200 00 10800 00 11400 00 12000 00 latitude longitude altitude km 2 000000 5 000000 28000 4 000000 10 00000 28000 6 000000 15 00000 28000 8 000000 20 00000 28000 10 00000 25 00000 28000 12 00000 30 00000 28000 14 00000 35 00000 28000 16 00000 40 00000 28000 18 00000 45 00000 28000 20 00000 50 00000 28000 22 00000 55 00000 28000 24 00000 60 00000 28000 26 00000 65 00000 28000 28 00000 70 00000 28000 30 00000 75 00000 28000 32 00000 80 00000 28000 34 00000 85 00000 28000 36 00000 90 00000 28000 38 00000 95 00000 28000 40 00000 100 0000 28000 www ieea fr IEEA 31 M dd LE nos 8 5 Maps Input data file GlobalMap 85 0050035 1800050073 date monday 1 1 2003 2200 flux_number 150 0 frequency LI www ieea fr IEEA d 9 Migrating from previous version to GISM version 6 53 Satellite trajectory The keyword time was renamed in time window For a satellite trajectory the keyword time start shall be used Maps GlobalMap instead of map coordinates keyword date as before maps flux number replace by flux number maps frequency replaced by frequency www ieea fr GISM_user_manual v6 53 27 02 11 9 2334 GISM user manual v6 5
4. 0 0 Q 0 0 Q Q 0 0 762288E 01 821385E 01 B49797E 01 S08886E 01 10191 8E 02 120797E 02 1l131338E 2 141804E 02 156958E 02 169978E 02 182382E 02 192509E 02 183583E 02 174382E 02 172032E 02 178852E 02 189303E 02 217322E 02 231782E 02 237992E 02 2362 72E 02 206789E 02 20193 9E 02 189822E 02 173508E 02 163160E 02 160415E 02 151073E 02 143561E 02 135358E 02 130335E 02 123911E 02 122338E 02 121449E 02 118687E 02 111315E 02 1l104477E 2 1004 90E 02 960621E 01 896533E 01 842352E 01 771452E 01 712984E 01 681901LE 01 654294E 01 636994 E 01 611882E 01 603 951E 01 60522 0E 01 61874 6E 01 659656E 01 697071E 01 FOROSSE OL 6864 34E 01 680 798E 01 66053 7E 01 652016E 01 641566E 01 608524E 01 S991 78E 01 5621156 01 5294 58E 01 506193E 01 ID gt gt r gt gt D gt DID D gt D DIDI O r gt D DO D DID D D gt D gt D D D r gt O r gt gt D gt D D D D gt DO O r gt O r gt D O D O D gt r gt gt r gt O r gt DO O gt gt r gt gt phase 298807E 03 2987 7 LE O0S 299469E 03 298860E 03 296034E 03 292014 E 03 248960E 03 247346E 03 282881LE 03 2744 51E 03 26413 56 03 250123E 03 237005E 03 2337260ET03 228183E 03 225673E 03 223187E 03 213924E 03 187752E 03 172429E 03 143847E 03 140867 E 03 141575E403 13384 6E403 12085 7E 03 123090E 03 1142076403 1085 90E 03 10893
5. 490000E 00 500000EHOQ 510000E 00 320000E 00 530000E 00 JAQOOQEHOQ 550000E 00 560 000E 00 570000E 00 580000E 00 S90000E 00 600000E 00 810000E 00 82 0000E 00 D D D gt gt ID gt DID DI gt r gt D r gt O r gt DIDI DID DID gt r gt gt gt D D r gt gt r gt gt D gt D D D gt gt r gt O r gt O r gt D O gt gt O O r gt gt r gt O r gt D O r gt O r gt gt space tm oooogoE 00 F6ll26e 04 152225E 03 228338E 03 304451E 03 s80563E 03 456676E 03 532788E 03 S08901LE 03 685014E 03 761126E 03 837233E 03 913352E 03 9894654E 03 1065 586 02 114168E 02 12178 E 02 1289381E 02 137003E 02 144614E 02 152225E 02 159837E 02 l167448E 02 175059E 02 182670E 02 19 282E 2 197893E 02 205504E 02 213115E 02 22072 7E O2 228338E 02 235949E 02 243 5606 02 2511 726 02 2a8 7836 02 2663 946 02 274005E 02 281617E O2 289228E 02 296839E 02 3044 516 02 312062E 02 319673E 02 B27 2846 02 334896E 02 342507E 02 S50118E 02 357 29E 02 365341E 02 372852E 02 380563E 02 388174E 02 395786E 02 403397E 02 411008E 02 418619E 02 426231E 02 433842E 02 441453E 02 449065E 02 456676E 02 464287E 02 471888E 02 intensity dB 0 0 Q Q 0 0 0 Q 0 0 Q Q 0 0 0 0
6. galileo point 2 point orbit trajectory Medium description slope BubblesRMS OuterScale All these parameters are optional Default values are assigned to each one Geophysical parameters flux number vdrift Scintillation analysis parameters frequency same seed optional LOSSpaceStep the space step along the line of sight optional Receiver Location receiver Map Analysis GlobalMap Analysis Period of time time window time start date tgps UT SLT Outputs options sampling frequency average duration of fades spectrum All these keywords are optional Keyword List Project name gps glonass Galileo point 2 point orbit trajectory slope BubblesRMS Outerscale flux number vdrift frequency same seed LOSSpaceStep receiver GlobalMap time window time start date tgps UT SLT sampling frequency average duration of fades spectrum www ieea fr o 9 GISM user manual v6 53 IFEA 27 02 11 3 1 Trajectory The satellite location may be defined by one of the following options gps glonass galileo Point2Point OrbitTrajectory 3 1 1 GPS constellation Yuma files are used GPS Yuma files can be downloaded from http www navcen uscg gov ftp GPS almanacs yuma GPS Yuma file example kkk Week 109 almanac for PRN 01 ID 01 Health 000 Eccentricity 0 5046367645E 002 Time of Applicability s 319488 0000 Orbital Inclination rad 0 9655654054 Ra
7. phase deg intensity_ dB 200 ERR na Be ne J Sooo S ul s uni MN M MUN t E M00 esce dne t ren ONSE ar E EA ee EE a00 ea ere E Me ey ENERO DI RN ee a ao cee Sa time_ s time_ s Figure 6 Intensity and phase time series for S4 0 89 6 2 Average duration of fades average_duration_of_fades_prn_30 100 amp 10 s 3 bar i g 0 1 i 8 i z 7 U 0 01 0 001 i i 40 30 20 10 0 10 fade level_ dB Figure 7 Average duration of fades for S4 0 89 www ieea fr 9 25 GISM user manual v6 53 IFEA 27 02 11 6 3 Spectrum Power densities 3 140 100 10 1 0 1 0 01 140 140 4 140 1409 l 4 1410 0 01 0 1 1 10 100 frequency Hz Phase Amplitude Figure 8 Intensity and phase spectrum www ieea fr IEEA 26 sd LE dir 6 4 Maps Figure 9 shows the correspondence between a Total Electron Content TEC map and a scintillation map Those two maps were obtained by modeling using NeQuick Radicella 2009 model for the TEC and GISM for scintillations They correspond to vertical links The electron density is consequently integrated along a vertical at each grid point on the map to get the TEC Slant observations may however exhibit higher values The propagation length inside the ionosphere would increase in that case and by consequence the levels obtained TEC F10 7 158 date 1 1 2883
8. 0 0 20 10 92 06 70 Exp 14 43 10 05 i34 Doppler shift Hz Co Oo Oo 0 OCC O0 0 OO 0 amp NO CO Oy 2 QC O1 OO tO HP OO OO Oo oo oa oD 1 0 m N RR N Q O gt Q t O O gt z Q O N RR N Q O Q Q O O G P Iono 62 42 08 44 54 54 78 46 19 10 405 132 51 45 08 238 30 69 67 58 95 295 68 19 GISM_user_manual v6 53 IEEA 27 02 11 4 3 Scintillations effects synthesis File name scintillations_synthesis txt Scintillations synthesis ground station name naha ground station coordinates latitude 26 00 longitude 128 00 altitude 0 00 PRN UT LT azimut elevation sat lat sat long S4 sigma phi deg deg deg deg rad 1 12 500 21 033 224 788 23 640 14 690 92 101 0 730 0 658 3 12 500 21 033 27 133 49 421 52 404 151 044 0 048 0 027 11 12 500 21 033 191 439 27 762 23 118 118 496 0 757 0 975 13 12 500 21 033 265 269 23 124 11 346 72 534 0 284 0 125 15 12 500 21 033 37 594 6 569 55 137 219 097 0 020 0 013 22 12 500 21 033 80 219 35 307 25 043 176 409 0 087 0 048 25 12 500 21 033 146 836 54051 34 181 166 533 0 822 1 352 27 12 500 21 033 317 379 26 532 52 189 68 689 0 046 0 022 3t 12 500 21 033 312 017 66 814 36 910 111 587 0 045 0 026 9 satellites in view ground station name naha ground station coordinates latitude 26 00 longitude 128 00 altitude 0 00 PRN UT LT Angular error Coh length PLL DLL C N Proba of LoL
9. 06 20 00 06 20 00 12 satellites in view operating frequency 5 6 15 16 18 21 22 25 26 29 30 14 14 14 14 14 14 14 14 14 14 14 20 20 20 08 20 20 20 20 20 20 08 20 20 08 08 08 08 08 08 08 08 08 synthesis txt azimut elevation deg deg 1575 420 MHz 28 16 6 33 113 68 49 74 145 26 0 47 275 63 36 28 220471 19 78 14 83 59 90 199 14 60 16 345 04 29 34 293 20 13 26 95 19 7 81 106 78 5 64 16 31 43 07 1575 420 MHz 28 05 4 39 110 10 49 15 2172 87 37 36 2214 52 21 63 16 69 62 39 194 98 59 07 344 88 31 61 295 25 12 34 97 28 8 34 108 93 5 88 15 93 40 65 18 Mean effects synthesis GISM v6 50 sat lat sat long deg deg 38 64 348 64 31 90 348 21 56 04 52 95 13 26 270 39 53 04 248 46 0 74 319 87 44 54 303 77 23 94 301 87 8 40 258 04 12 17 26 08 22 43 31 63 12 28 324 01 40 26 349 91 30 08 348 98 15 31 270 67 52 21 251 12 2 81 320 07 45 97 305 46 21 98 302 30 10 40 258 29 214 77 26 26 24 44 32 04 14 30 324 33 www ieea fr TEC 127 21 52 40 34 234 Tia 112 19 12 45 133 21 50 32 22 115 18 12 47 95 225 67 36 56 37 45 lid 85 22 72 41 48 38 11 61 90 89 24 26 5 28 09 67 GISM user manual v6 53 27 02 11 Faraday rotation deg el 0 0 0 0 el 0 0 0 G 30 05 01
10. 22 23 24 25 LT LT Figure 11 Intensity and phase scintillation indices on day 314 GPS week N 377 obtained by modeling Measurements The local time corresponds to hours in GPS time Each point corresponds to a 1 mn sample Only points with a S4 value greater than 0 2 were retained in the analysis The points are clustered every evening at post sunset hours The scintillation activity occurred quite regularly that week with comparable levels The S4 average value is about 0 4 The flux number that week GPS week N 377 was equal to 90 The phase fluctuations are plotted concurrently The mean value is about 0 2 consequently lower than the S4 value This observation is quite general In addition it has to be noticed that some points exhibit high values This is due to phase jumps www ieea fr IEEA 28 EE Ae Modelling The case was replayed one day using the Yuma files Another week day will not bring significant differences considering that the geophysical parameters would have been quite identical As mentioned previously the model provides a mean value It overestimates the number of affected links due to the fact that the probability of occurrence is not considered Only the mean values can be compared For the intensity they compare quite well It is about 0 4 in both cases For the phase the mean measurements value is around 2 The value obtained by modelling is slightly greater In both cases the phase RMS is low
11. 9E 03 109511E 03 107429E 03 102146E 03 103194E 03 102073E403 l0z323E 03 105020E 03 103367E 03 L023 67E 03 9823 20E 02 97 5469E 02 956622E 02 96141 26 02 958126E 02 972888E 02 967332E 02 952092E 02 933004E 02 9053 76E 02 873096E 02 854393E 2 845988E 02 835733E 2 BLOGSSE 02 6144 29E 02 814522E 02 B17039E 02 B17347E 02 B13418E 02 B15059E 02 797182E 02 Z78461E 02 Z70854E 02 ZZ2410E 02 www ieea fr GISM_user_manual v6 53 27 02 11 9 21 GISM_user_manual v6 53 IEEA on 5 Input Parameters Default Values 5 1 Medium s definition The medium is defined by three parameters the fluctuations spectrum slope the average size of inhomogeneities and the strength of fluctuations The fluctuations spectrum slope The slope coefficient of the power law spectrum and the turbulence strength can be deduced from measurements Figure 3 shows the slope value deduced from measurements in Cayenne recorded during the PRIS measurement campaign 3 One week of 50 Hz raw data files was used to obtain these plots A slope value equal to 3 is the most probable value This is in agreement with what is usually considered in the literature 7 The slope value decreases with time after sunset corresponding to the fact that the inhomogeneities sizes decreases with time after sunset It should be noticed however that the PRIS measurement campaign was done in a year close to solar minimum High solar activity value
12. EEA t sd LE ir Global Ionospheric propagation Model GISM USER MANUAL release n 6 53 January 2011 www ieea fr 9 Mo GISM user manual v6 53 IEEA on TABLE OF CONTENTS ME T troduction e n 4 2 GISM implementation 6 2 1 Task 1 Create a project directory cii cciscscscscsssssessecdsonssonssoesseessessecesossoecsosesccessoocsseseeessecesessenes sees soussnoseeosceossevssensse 6 2 2 Task 2 MPU nn M 7 2 3 Task PED IUD 7 TUL nro NC EP 8 S BIR TALLI D A l T 9 SM NEG SUITES 9 Be Qi GIOMASS M 10 3 3 Galil egu 11 3 VA eumd aE 11 3 22 Medium Description ERE Nm 12 3 3 Geophysical Parameters eee renes re eee eer Feu e etre sacs p Saura pee vet aeuo Uie ru Sisa Se as ada ga seta 12 3 4 Scintillation Analysis Parameters 13 3 5 Receiver Location sisien 14 3 6 Map Analysis sscssiccsscci
13. Satellite Systems GNSS telecommunications remote sensing and earth observation systems The signal fluctuations referred as scintillations are created by random fluctuations of the medium s refractive index which are caused by inhomogeneities inside the ionosphere These inhomogeneities or bubbles or more generally the turbulences develop under several deionization instability processes These processes start after sunset when the sun ionization drops to zero consequently at nighttime To produce signal scintillation the bubbles sizes should be below a typical dimension typically one km such that the diffracting pattern is inside the first Fresnel zone The Fresnel zone dimension also depends on the distance from the Ionospheric Pierce Point usually defined at about 350 km height to the receiver and on the frequency The Global Ionospheric Propagation Model GISM presented in this document aims to calculate these effects in particular e The Line of sight errors e The Faraday rotation effect on polarization being an anisotropic medium ionosphere layers will impact a linear polarized wave by rotating its polarization plane e The propagation Delay the ranging error is proportional to the TEC and to the inverse square of the frequency e The scintillation effects phase and amplitude scintillations shorter correlation distances with respect to space time and frequency cycle slips loss of lock GISM model uses the Mult
14. carried out under one ESA ESTEC contract For this study a number of receivers were deployed both at low and high latitudes in particular in Vietnam Indonesia Guiana Cameroon Chad and Sweden These receivers were dedicated receivers operating at 50 Hz A data bank has been constituted and the scintillation characteristics have been derived from an extensive analysis of this data bank For assessment of the model performance we have selected one week of measurements at Cayenne French Guiana taken from the PRIS data bank The results are presented on Figures below SA all satellites Sigma Phi all satellites Cayenne days 314 to 319 year 2006 Cayenne days 314 to 319 year 2006 x 001 E 4 me ie aa SE SOY PKS SSS SI IPO o PRN13 l i i i Y PRNID E E O ici eed ined PPM zr T FPRAJ S p B l PRN28 B 06 Lee Me eec emn l T m PRN12 amp l We iis PRN8 A e E PRN29 a l 4 Y PRN26 D g e Y PRN9 npe E as OM E eee s PEN ki d P 1 L aA oi u f O i mho calme c mm om m l r Q Li mia si ee L a Ly 40 20 0 20 40 60 80 40 20 0 20 40 60 80 LT LT Figure 10 Intensity and phase scintillation indices measurements on GPS week N 377 Cayenne day 314 2006 Cayenne day 314 2006 GISM GISM 4 4 E 2 o O L r rr nuraranetnateneneneLARenantnenPinenetanenetunetnti eo So 18 19 20 21
15. time time_window time_start date UT SLT tgps If the calculation applies to a GPS constellation the time window shall be specified If the calculation applies to a satellite defined by its trajectory the initial time and date shall be initialised If the calculation applies to a Global or regional map the date shall be specified GPS UT or Solar Local Time UT longitudinal delay can be considered Examples ftime window Tuesday 11 05 2001 2000 1 start of analysis day name date day month year hour minute second Tuesday 11 05 2001 2100 l end of analysis day name date day month year hour minute second 050 time step hour minute second all values integer time_start Tuesday 11 05 2001 200 0 1 start of analysis day name date day month year hour minute second all values integer date Tuesday 11 05 2001 20000 1 date of analysis day name date day month year hour minute second all values integer UT or SLT or tgps www ieea fr 9 15 GISM_user_manual v6 53 IEEA on 3 8 Outputs options sampling frequency average duration of fades spectrum All these keywords are optional Additional files will be created for each one of the above optional calculations Each new link will add data to the files In order to limit this size it may be convenient to limit the creation of such files to one particular link sampling frequency This will create time series files of
16. will correspond to a specific directory This is the first task to be completed by the user This directory shall be located inside directory Scenarios Before GISM execution this directory must contain two files The first one named data txt contains the link or map data The second one is the satellite trajectory GISM Scenarios Data txt Yuma file Figure 1 GISM implementation The executable file must be at the same level than Scenarios and bin www ieea fr 9 a GISM_user_manual v6 53 IEEA on 2 2 Task 2 inputs e create the data txt file inside the corresponding folder e Include a trajectory file in the project folder For GPS a Yuma file GPS Yuma files can be downloaded from http www navcen uscg gov ftp GPS almanacs yuma For Glonass a Yuma file The Glonass Yuma file contains one additional datum for the frequency dependency of the satellite The corresponding files are stored for Galileo For a trajectory a txt file containing the trajectory 2 3 Task 3 Execute Once the data file and the trajectory file are properly created and stored in a directory the execution can be launched from a DOS window gism project name on a DOS window www ieea fr IEEA 8 a LE ir 3 Input data The input data file must be saved inside the directory corresponding to the problem of interest The following sections may be addressed Satellite position One of the following options gps glonass
17. 139 32 249 61 685 24 26559 125 0 938E 02 56 323 93 038 28 230 63 017 25 26561 018 0 906E 02 53 757 111 155 145 591 107 498 26 26560 430 0 131E 01 55 487 16 709 89 632 155 750 27 26559 740 0 153E 01 54 017 145 610 146 944 21 611 28 26572 707 0 531E 02 54 992 137 061 150 616 68 702 29 26562 156 0 843E 02 55 308 106 837 87 942 162 146 30 26559 459 0 585E 02 54 047 77 274 151 998 69 371 31 26559 826 0 103E 01 54 090 49 513 92 451 130 243 www ieea fr 9 10 GISM_user_manual v6 53 IEEA on 3 1 2 Glonass Glonass Yuma file example week KK Week 109 almanac for PRN 01 ID 01 Health 000 Eccentricity 0 5046367645E 002 Time of Applicability s 319488 0000 Orbital Inclination rad 0 9655654054 Rate of Right Ascen r s 0 7943188009E 008 SORT A m 1 2 5153 693359 Right Ascen at Week rad 0 1580654101E 001 Argument of Perigee rad 1 732023850 Mean Anom rad 0 1213174697E 001 Af0 s 0 1964569092E 003 Afl s s 0 0000000000E4 000 week 109 frequency channel 8 The Glonass Yuma file includes one additional line with respect to GPS Yuma file This additional line specifies the frequency channel of the corresponding PRN required for the frequency calculation which depends on the PRN for the Glonass constellation www ieea fr 9 11 GISM user manual v6 53 IFEA 27 02 11 3 1 3 Galileo In case of Galileo no Yuma file is required The data is already stored The corresponding valu
18. 3 IEEA on 10 References 1 2 3 4 5 6 7 B niguel Y A Global Ionosphere Scintillation Propagation Model for Equatorial Regions submitted to Space Weather Space Science SWSC B niguel Y Global Ionospheric Propagation Model GIM a propagation model for scintillations of transmitted signals Radio Sci Vol 37 N 3 May 2002 B niguel Y J P Adam N Jakowski T Noack V Wilken J J Valette M Cueto A Bourdillon P Lassudrie Duchesne B Arbesser Rastburg 2009 Analysis of scintillation recorded during the PRIS measurement campaign Radio Sci 44 doi 1029 2008RS004090 Kintner P H Kil T Beach E de Paula Fading timescales associated with GPS signals and potential consequences gt Radio Science Vol 36 N 4 731 743 DasGupta A A Paul S Ray A Das S Ananthakrisnan Equatorial bubbles as observed with GPS measurements over Pune India Radio Science 2006 Vol 41 RS5S28 Radicella S M The NeQuick model genesis uses and evolution Annales of Geophysicae Vol 52 N 3 4 June August 2009 Wernik A L Alfonsi M Materassi Scintillation modeling using in situ data Radio Sci Vol 42 2007 doi 0 1029 2006RS003512 www ieea fr
19. 56 000 0 000 240 000 306 660 27 29993 711 0 000E 00 56 000 0 000 240 000 346 660 28 29993 711 0 000E 00 56 000 0 000 0 000 20 000 29 29993 LLL 0 000E 00 56 000 0 000 120 000 20 000 30 29993 711 0 000E 00 56 000 0 000 240 000 20 000 3 1 4 Orbit trajectory orbit_trajectory File name Coordinate system Two possibilities e ECEF relative time along the trajectory s amp x y z coordinates m in the earth referential e latitude longitude altitude km with respect to ground plus relative time hrs along the trajectory A calculation is performed for each line of the trajectory file In both cases the time considered is a relative time along the trajectory The initial time is defined by the time_start keyword time_start monday 14 03 1999 20 00 0 www ieea fr 9 12 GISM_user_manual v6 53 IEEA on 3 2 Medium Description slope BubblesRMS OuterScale All these parameters are optional Default values are assigned to each one Examples slope 4 BubblesMS 0 1 OuterScale 500 l in meters 3 3 Geophvsical Parameters Flux number vdrift The Flux number is the solar spot number The ITU recommendation is to limit this value to 193 However this limitation has been removed in the NeQuick2 version used in GISM Example fflux number 150 0 vdrift 100 in meters second www ieea fr IEEA il 3 4 Scintillation Analysis Parameters frequency same seed optional LOSSpaceSte
20. F2 layer the NeQuick uses a profile formulation which includes five semi Epstein layers with modelled thickness parameters Three profile anchor points are used the E layer peak the F1 peak and the F2 peak that are modelled in terms of the ionosonde parameters foE foF1 foF2 and M 3000 F2 These values can be modelled e g ITU R coefficients for foF2 M3000 or experimentally derived A semi Epstein layer represents the model topside with a height dependent thickness parameter empirically determined The NeQuick package includes routines to evaluate the electron density along any ray path and the corresponding Total Electron Content TEC by numerical integration NeQuick2 Year2000 Month 4 UT 1200 45 N 14 E Azimuth 180 3000 TA T T TEC 90 41 4 TECU TEC 60 626 TECU TEC 30 94 4 TECU 2500 m TEC 10 143 9 TECU 2000 s km 1500 1000 500 1 x10 1 x10 1 x10 2 1 x 107 N s m Figure 5 Example of NeQuick 2 profiles and TEC along ray paths Different colours correspond to different path elevation angles 90 means vertical profile and TEC from Radicella 2009 6 www ieea fr v 24 GISM user manual v6 53 IFEA 27 02 11 6 Outputs 6 1 Time series time series 11 9 2000 prn 30 freq 1575 time series 11 9 2000 prn 30 freq 1575 800 A 10 00 societe Liceo bones m bons J 400 u L pen nocet M 4 20 H Melle k ll
21. UT 22 080 4 F10 7 158 date 1 1 2803 UT 24 08 80 70 60 50 3 40 5 30 gt 20 i 16 8 156 108 58 8 50 100 158 longitude Figure 9 TEC left panel and scintillation map right panel obtained bv modeling Figure 9 was obtained with a solar radio flux at 10 7 cm set to 150 It corresponds to a high value Universal time is 10 p m for the TEC map and 12 p m for the scintillation map At this time the peak values for the TEC occur in the Pacific Ocean area For the scintillations the time duration of the events is a few hours after sunset This is what gives the model Both plots reproduce the same features regarding the peak values on both sides of the magnetic equator The values decrease increasing the latitude For scintillations the model calculates the effects at the equatorial regions The high latitudes regions are also concerned by this problem but this is not taken into account bv the model The TEC maximum is 80 TEC units which is a significant value It is directly linked to the solar flux value The peak value for the intensity RMS S4 parameter is 0 7 Such a value corresponds to strong fluctuations It is also linked to the electron density levels Depending on the signal to noise ratio one receiver may lose lock at this level www ieea fr sja GISM_user_manual v6 53 IEEA on 7 Comparison with measurements The results reported hereafter are taken from the PRIS measurement campaign 3
22. al parameters F10 7 150 00 year 2004 month 5 day of month 11 yuma file for week number 246 PRN Semi major axis Eccentricity Inclination Argument of perigee RAAN Mean anomaly 3 26559 9536 0 556E 02 53 214 31 199 1 384 84 027 B 26560 893 0 522E 02 53 612 47 594 58 508 99 BBB 6 26561 340 0 555E 02 53 645 115 540 4 417 29 022 10 26560 289 0 511E 02 56 157 17 473 126 425 153 285 14 26559 207 0 141E 02 56 041 83 299 174 372 64 992 15 26559 936 0 886E 02 55 392 127 520 69 978 354291 16 26561 385 0 246E 02 55 057 81 499 54 398 98 448 18 26559 766 0 473E 02 552222 169 252 128 304 112 793 21 26559 951 0 869E 02 54 624 171 048 68 398 35 646 22 26559 0165 0 489E 02 55 071 81 535 128 870 129 187 25 26559 896 0 114E 01 54 118 90 580 119 146 73 335 26 26559 779 0 154E 01 56 265 33 915 71175691 58 514 29 26560 299 0 823E 02 56 090 E S 2175 553 176 106 30 26559 699 0 733E 02 54 008 72 705 56 145 159 797 Statistics CPU time Lecture des fichiers d entree 6mn 8 05 s 47 43 Calcul scintillations 0 00 s 0 00 Post traitement 6 mn 47 94 s 52575 Total 12 mn 55 98 s 100 00 end of job www ieea fr IEEA 4 2 Mean effects synthesis file name mean_effects_buget_link PRN UT Range delay operating 5 23 6 234 10 23 15 23 16 23 18 23 21 23 22 23 25 23 26 23 29 234 30 23 LT frequency 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00 06 20 00
23. er than the intensity RMS and in both cases some points exhibit high values due to the phase jumps www ieea fr 9 29 GISM_user_manual v6 53 IEEA on 8 Examples 8 1 Scenarios The scenarios considered are Simulation assuming static user and satellite constellation Simulation assuming static user and static satellite i e a point to point link Simulation assuming static user and moving satellite trajectory specific locations and times Global and regional maps of vertical S4 and o The input data files for each one of these different cases are presented in the next sections 8 2 Simulation assuming static user and satellite constellation Input data file gps Yuma246 txt frequency LI SLT time_window tuesday 11 05 2004 20 0 0 wednesday 11 05 2004 20 0 0 050 flux_number 150 0 receiver Cayenne 4 49 27 307 38 12 0 www ieea fr o IEEA 30 8 3 Simulation assuming static user and static satellite point to point link Input data file point_2_point 0 35 3 65E4 frequency LI UT time tuesday 11 10 2004 0 0 0 tuesday 11 10 2004 7 0 0 0120 flux_number 193 recelver Kourou 5 4 48 53 22 120 8 4 Static user trajectory GISM_user_manual v6 53 27 02 11 Input data file orbit_trajectory txt orbit_trajectory satellite_trajectory txt geodetic frequency L1 SLT time_start monday 14 09 2000 21 00 0
24. es are reproduced below constellation parameters printed in history file PRN Semi major axis Eccentricity Inclination Argument of perigee RAAN Mean anomaly 1 29993 711 0 000E 00 56 000 0 000 0 000 0 000 2 29993 TLI 0 000E 00 56 000 0 000 0 000 40 000 3 29993 711 0 000E 00 56 000 0 000 0 000 80 000 4 29993 711 0 000E 00 56 000 0 000 0 000 120 000 5 29993 711 0 000E 00 56 000 0 000 0 000 160 000 6 29993711 0 000E 00 56 000 0 000 0 000 200 000 T 29993711 0 000E 00 56 000 0 000 0 000 240 000 8 29993 1 1 0 000E 00 56 000 0 000 0 000 280 000 9 29993 711 0 000E 00 56 000 0 000 0 000 320 000 10 29993 711 0 000E 00 56 000 0 000 120 000 134 330 11 29993 711 0 000E 00 56 000 0 000 120 000 534330 12 29993 711 0 000E 00 56 000 0 000 120 000 93 330 13 29993 1711 0 000E 00 56 000 0 000 120 000 133 330 14 29993 711 0 000E 00 56 000 0 000 120 000 1732330 15 29993 l 0 000E 00 56 000 0 000 120 000 213 330 16 29993 711 0 000E 00 56 000 0 000 120 000 253 330 17 29993 711 0 000E 00 56 000 0 000 120 000 293 330 18 29993 711 0 000E 00 56 000 0 000 120 000 333 330 19 29993 711 0 000E 00 56 000 0 000 240 000 26 660 20 29993 711 0 000E 00 56 000 0 000 240 000 66 660 21 29993 711 0 000E 00 56 000 0 000 240 000 106 660 22 29993711 0 000E 00 56 000 0 000 240 000 146 660 23 29993 711 0 000E 00 56 000 0 000 240 000 186 660 24 29993 711 0 000E 00 56 000 0 000 240 000 226 660 25 29993 711 0 000E 00 56 000 0 000 240 000 266 660 26 29993 711 0 000E 00
25. intensity and phase average duration of fades Performs the calculation of the average duration of fades spectrum Calculates the spectrum of the intensity and phase of received signal Examples sampling frequency 100 in Hz 500 in seconds The first number 100 in the above example is the sampling frequency The second number 500 is the sample time duration average duration of fades spectrum www ieea fr IEEA 16 sd LE dir 4 Output files Inside the folder corresponding to the problem under analysis the following files are created during execution one history file gt one file for the mean errors synthesis one file for the scintillation errors synthesis one summary file n files for the mean errors n files for the scintillation errors onoption n Rinex files signal scintillation noise amplitude and phase Scenarios Data txt Yuma file history txt mean_effects_synthesis txt scintillations_synthesis txt Summary txt Ground_station_name _date_prn_n xx_mean_effects Ground_station_name _date_prn_n xx_scintillations Figure 2 Output files www ieea fr 17 GISM_user_manual v6 53 IEEA 27 02 11 4 1 History File File name history txt GISM v6 50 input data GPS constellation frequency 1575 42 MHz ground station name Kourou time of analysis start 20 000 hours LT end 21 000 hours LT time step 5 000 mn Geophysic
26. iple Phase Screen technique MPS With this technique the medium is divided into successive layers each of them acting as a phase screen The locations and altitudes of both the transmitter and the receiver are arbitrary The link can consequently go through the entire ionosphere or through a small part of it The whole calculation for one particular link is composed of two steps e The calculation of the Line Of Sight LOS e The calculation of scintillations The calculation of the Line of sight is done using a ray technique GISM uses the NeQuick model to provide the value of the electron density inside ionosphere required at any time and location At the end of this calculation the LOS errors the Faraday rotation and the delays are calculated The LOS being determined the scintillations are then calculated To do this at each screen location along the line of sight the parabolic equation PE is solved This calculation requires the knowledge of the medium statistical characteristics They are defined with respect to the ionosphere electron density mean value at all points along the LOS www ieea fr IEEA ee EE Ae GISM model estimates the scintillation parameters from the knowledge of the time series at receiver level using the signal intensity and phase and its correlation and structure functions In case of strong scintillations typically S4 gt 0 7 the phase may exhibit cycle slips with consequences on the receiver phase loop I
27. mr km deg m 1 12 500 21 033 0 11 0 27 17 52 23 97 30 13 0 061 3 12 500 21 033 0 00 0 62 5 99 0 00 35 78 0 000 11 12 500 21 033 0 18 0 23 21 17 30 72 31 31 0 045 13 12 500 21 033 0 01 0 60 9 237 7 33 29 82 0 000 15 12 500 21 033 0 00 0 62 6 99 0 00 24 99 0 000 22 12 500 21 033 0 00 0 62 6 99 0 00 32 97 0 000 25 12 500 21 033 0 52 0 11 318 88 515 13 24 55 0 428 27 12 500 21 033 0 00 0 62 6 99 0 00 30 60 0 000 31 12 500 21 033 0 00 0 62 6 99 0 00 37415 0 000 9 satellites in view www ieea fr 4 4 Time series IEEA 20 File name time series date prn N freq xxxx txt The sampling frequency was set to 100 Hz in this example ID DII DDDIUDIDI DI DIUDDIIDIDISIDIDIDDIDISIIDDIDIDISIDIDIDIDIDIDIDIDIIDmDDIIDIDIDII DIDIDIDIDI 2 2 gt 2 r gt gt gt gt time_ts 3 000000E 0O0 100000E 01 200000E 01 300000E 01 400000E 01 00000E O1 B500000E 01 zQO OODE 0T B800000E 01 B 00 000E 01 100000E 00 110 000E 00 120000E 00 130000E 00 140000E 00 150000E 00 160000E 00 170000E 00 180000E 00 180000E 00 200000E 00 2al 000EFOQ0 220000E 00 23 0000E 00 240000E 00 25 0000E 00 260000E 00 270000E 00 280000E 00 290000E 00 s00000E 00 310 000E 00 320000E 00 330000E 00 340000E 00 350000E 00 350000E 00 370000EF 00 380000E 00 380000EHO00 400000E 00 410000E 00 420000E 00 430000E 00 440000E 00 450000E 00 460000E 00 47 0000E 00 480000E 00
28. p the space step along the line of sight optional frequency range first frequency step number of frequencies the first two values in MHz or frequency L1 or L2 or L5 or El or E2 or E5 or E6 Or frequency other value in MHz fisame seed GISM user manual v6 53 27 02 11 This keyword allows running several cases in the same conditions to obtain in particular the frequency correlation GISM uses a random number generator The seed is the PC clock If the same seed keyword is used the seed will be identical for successive runs LOSSpaceStep 15 e3 in meters This keyword is optional It allows defining a space step along the Line Of Sight The default value is 15 km as above The algorithm convergence with the space step value is commented at section 6 www ieea fr IEEA 14 EE Ae 3 5 Receiver Location receiver Name of receiver Latitude degrees minutes seconds longitude degrees minutes seconds altitude meters Example receiver MarakParak 60011600 0 0 latitude degrees minutes seconds longitude degrees minutes seconds altitude the first 6 data integer the last one real 3 6 Map Analysis GlobalMap Example GlobalMap 50 0020051 latitude minimum degrees minutes seconds step latitude id number of steps 100 0 0 2 0 0 76 longitude minimum degrees minutes seconds step longitude id number of steps all values integer 3 7 Analysis Period of
29. s might be different in particular for the strength slope Power spectrum detrended phase p index histogram 500 r I F T T T 1 0L 7T 137 T1 a a TO 400 200 f 0 04 08 12 1 6 2 24 28 32 3 6 4 4 4 Time after sunset Range Figure 3 Slope distribution GISM uses 1D phase screen It has been shown 1 that using ID phase screens to define the medium is equivalent to a 2D isotropic medium provided that the slope is increased by one The GISM spectrum slope default value is set to 4 Average value of inhomogeneities dimension The inhomogeneities dimensions which contribute to scintillations are linked to the first Fresnel zone dimension given by expression y Ad with d the distance from the fluctuating medium to the receiver In the L band the dimension is a few hundreds of meters The default value is set to 500 meters www ieea fr o 22 GISM_user_manual v6 53 IEEA on Fluctuation strength This parameter defines the RMS electron density value with respect to the mean value 0 05 is an average value 0 15 is considered as a maximum value The default value is 0 1 5 2 Geophysical parameters Flux number The flux number may be set to any value The past and future values of this index are shown on the following plot taken from NOAA web site SES Solar Cycle Sunspot Number Progression Observed dete through Feb 2010 ERTS Sunspot Number I
30. sccisessteessccrscosssosteodseteseeceessteus 14 3 7 Analysis Period Of Gime icccsscisssssscsscsosssssssssssssssoosssssssssssssssescssosessssssssseedsssessssassoaseseseessssscsssses sosessssscessssssssonsosssesses 14 3 8 Outputs OPTIONS ses EE I clt 15 MDE ISO a a E ha aaa munasi Q ua E EE 16 4 1 Hist ry Mole 17 4 2 Mean effects Syntliesis roce u u i aaa eta pea ees eee eene o0dshoesicetscesavecsecesedesansesasescessbescessatesesssauassesveeasoes 18 4 3 Scintillations effects synthesis 7 s u tre errante ene eer soasscesesesecesesoseseceusosetseeessoedsesssoeddessseesseesseccsessseesees 19 DR MIO NI ETE TUTTO LC LL IT RR 20 5 Input Parameters Default Values 21 5 1 Medium d finifi ni 21 5 2 Geophysical parameters M 22 5 3 Nequick Sun osoo 23 UNT ME 24 6 1 TAM SOV IOS u us ayasa DESDE D TL LLLI 24 6 2 Average duration of fades aaa aaa aaa aassessssssssassssssossssassossessssassesssssssessssossesssssssesssssssssssssssssesssssassesssos 24 6 3 SPECtr UM E
31. t may also in that case lead to losses of lock for one or several satellites GISM model allows considering either a trajectory described by a list of successive points or a constellation GPS Galileo or Glonass An orbit generator has been introduced for this capability The input in that case is the Yuma file GISM allows considering either links from a receiver to a satellite or a constellation or maps Details on the theoretical formulation and corresponding algorithm may be found in the GISM technical report 1 2 This document is organized as follows Section 2 presents the code organisation Section 3 presents the input data Section 4 presents the output files Section 5 defines the input parameters default values Section 6 is related to the algorithm convergence Section 7 presents the mapping capability Section 8 is related to the output options Section 9 presents some input data files for typical scenarios Section 10 indicates the changes in the input data file with respect to the previous version www ieea fr 9 6 GISM user manual v6 53 IEEA on 2 GISM implementation The 4 tasks required for execution are detailed below Task 1 Create a directory inside which will be located all files input and output related to the problem case Task 2 Hill the input data file Task 3 Define the satellite location and trajectory Task 4 Run a test case 2 1 Task 1 Create a project directory Each problem
32. te of Right Ascen t s 0 7943188009E 008 SQRT A m 1 2 5153 693359 Right Ascen at Week rad 0 1580654101E 001 Argument of Perigee rad 1 732023850 Mean Anom rad 0 1213174697E 001 Af0 s 0 1964569092E 003 Af1 s s 0 0000000000E 000 week 109 constellation parameters printed in the history file PRN Semi major axis Eccentricity Inclination Argument of perigee RAAN Mean anomaly 1 26560 555 0 505E 02 55 323 99 238 90 565 69 510 2 26559 5299 0 213E 01 53 464 115 284 155 177 103 414 3 26559 855 0 238E 02 53 588 29 984 934 35B 178 421 4 26558 496 0 556E 02 55 743 24 585 29 194 25 230 5 26558 809 0 312E 02 53 640 25 810 153 976 1349929 6 26559 604 0 685E 02 54 021 128 902 90 729 74 593 7 26560 711 0 121E 01 54 122 114 051 92 447 170 945 8 26560 350 0 815E 02 54 966 117 344 151 123 91 425 9 26560 127 0 123E 01 54 171 43 545 148 044 59 600 10 26559 680 0 449E 02 56 097 4 843 29 482 100 709 11 26560 102 0 995E 03 52 749 133 26 75 33 650 124 151 13 26560 012 0 184E 02 555563 6 589 89 356 68 616 14 26559 840 0 224E 02 554 258 28 220 89 114 102 658 15 26559 725 0 806E 02 56 114 100 564 26 571 112 876 17 26560 027 0 135E 01 562222 178 768 24 278 48 302 18 26559 559 0 236E 02 55 108 159 857 32 216 9 208 20 26560 625 0 221E 02 55 150 121 231 2942231 88 161 21 26559 398 0 177E 01 56 077 138 349 29 821 84 738 22 26558 910 0 145E 01 53 436 40 565 154 405 122 015 23 26556 625 0 156E 01 56 263 104
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