OVERVIEW OF THE ANOMALIES AT THE KOUROU BEACON SITE

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1 OVERVIEW OF THE ANOMALIES AT THE KOUROU BEACON SITE Ph. Yaya, H. Capdeville, B. Frayssinet, B. Nhun-Fat, J.-J. Valette, L. Soudarin CLS, Collecte Localisation Satellites, France contact : yaya@cls.fr - 1 -

2 Content Motivation of the work Signal analysis Attenuations of on-board received power Measurement losses Comparison with GPS reception Mask? Measurement analysis POE residuals Ionospheric correction variability Troposphere contribution Conclusions - 2 -

3 Motivation : situation of Kourou Signal losses 400 MHz (cf. B. Bonhoure, 1999) Radio-electric interferences (jamming campaign) Routine POE processing Guier : Kourou residuals systematically high High elimination rate + seasonal effect Orbit : Kourou s RMS is higher than DORIS network s RMS - 3 -

4 Some examples KRVB R M S G u ie r s ta tio n (S p o t5, n o v 0 5 ) 4,0E-03 4.E-03 3,5E-03 3,0E-03 2,5E-03 2,0E-03 Guier RMS of SPOT5 POE (Nov. 05) 1,5E-03 1.E-03 1,0E-03 A DEB R IPB SP JB T H UB ST JB SCRB METB H EMB SYPB SANB YAS B R OTB SAKB REUB B EMB K ESB YELB MSPB H BLB N O WB MATB F AIB SODB JIU B K OLB MAL B C ROB D IO A C ADB C ICB PD MB MORB TLHA F U TB MIAB MANB EAS B TRIB EVEB R EZB LIBB PA QB SALB A SDB K R VB KIUB 90% mm/s 35% 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35% Kourou : Taux de mesures traitées POE SPOT5 kourou réseau entier 1/8/03 30/9/03 29/11/03 28/1/04 28/3/04 27/5/04 26/7/04 24/9/04 23/11/04 22/1/05 23/3/05 22/5/05 21/7/05 Rate of validated measurement for SPOT5 POE (August 03 July 05) Kourou : RMS d'orbite POE SPOT5 mm/s 0,80 0,75 0,70 0,65 0,60 0,55 0,50 0,45 0,40 0,35 1/8/03 30/9/03 29/11/03 28/1/04 28/3/04 27/5/04 26/7/04 24/9/04 23/11/04 22/1/05 23/3/05 22/5/05 21/7/05 Orbit RMS of SPOT5 POE (August 03 July 05) kourou réseau entier - 4 -

5 Analysis method Analysis of the attenuation of the received signal power (400 MHz and 2GHz) DEF : attenuation = actually received power expected received power Analysis of signal losses DEF : loss = no signal on either 400 MHz or 2 GHz channel Analysis of the POE orbit processing statistics Context of the work : 1 year (Oct. 04 to Nov. 05) The whole DORIS missions (except Jason POE due to SAA effect) - 5 -

6 Plan Power attenuations Signal losses POE orbit résiduals Measurement correction - 6 -

7 Power attenuation (1) Comparison of the received power levels Mean values of the power attenuations (low-pass filter) 400 MHz better received than 2 GHz Only D2 on the 400 MHz channel has the expected level - 7 -

8 Power attenuation (2) Seasonal effect Mean over 500 measurements sliding window of the power attenuation for ENVISAT Std dev. over 500 measurements sliding window of the power attenuation for ENVISAT Beginning of Nov : change of beacon type More dispersion frome October to March - 8 -

9 Power attenuation (3) Local hour effect Power attenuation for SPOT4 (all passes Oct. 04 Oct. 05) Morning passes (descending) Abnormal situations during the evening : - more dispersion - some very low levels - some high levels Evening passes (ascending) Same behaviour for the other DORIS instruments - 9 -

10 Power attenuation (4) Geographical effect Winter (min elev = 12 ) Summer (min elev = 8 ) 2 GHz 2 GHz Presence of an interference source (mask?) - 20 db and more - N.W. from Kourou - Persistent all the year - Seen on all missions 400 MHz 400 MHz # More fluctuations during winter # Good 400 MHz reception on a western area # Weak 2 GHz reception circle at high elevation db db

11 Plan Power attenuations Signal losses POE orbit residuals Measurement corrections

12 Signal losses (1) Seasonal effect 15 days signal losses on SPOT5 Oct. 04 Nov MHz - More losses from Nov. to March on the 400 MHz channel - The same for the other missions 2 GHz

13 Signal losses (2) Local hour effect Signal losses on SPOT5 vs. local hour - Evening passes - Same for the other missions - Jason : 2GHz losses whatever the local time constant presence of the interference source

14 (SPOT4 similar to SPOT2) Signal losses (3) Geographical effect 2 GHz 2 GHz 400 MHz 400 MHz

05) 2 GHz 2 GHz 400 MHz more affected The interfered area affects only the 2GHz losses

15 Signal losses (4) Geographical effect Signal losses on ENVISAT (Oct. 04 Oct.05) Signal losses on JASON (Oct. 04 Oct.05) 2 GHz 2 GHz 400 MHz more affected The interfered area affects only the 2GHz losses 400 MHz 400 MHz Heliosynchronous sat. : losses only on the ascending passes (evening) Ascending passes with high elevation : less affected

16 The guilty interference source Antenna of the DORIS beacon Reception antenna of the CNES 2GHz network MASK

17 Comparison with GPS reception L2 measurement losses of lock Scintillation indices (empirical, [0-1], based on the phase fluctuations, same for both Kourou receiver) h 6h 12h 18h 0h Local hour The phenomenon is more important on the evening AND from October to March IONOSPHERIC SCINTILLATIONS

18 Plan Power attenuations Signal losses POE orbit residuals Measurement corrections

19 POE orbit residuals (1) Comparison Kourou/DORIS network SPOT2 monthly RMS : influence of latitude Kourou equatorial latitudes ( λ <15 ) mean & high latitudes ( λ >15 ) M: ascending ( montants ) D: descending Kourou RMS systematically higher than the other the network beacons (included the equatorials) Asc. pass RMS (evening) very high from October to March Asc. pass RMS lower than the desc. pass RMS from May to September Same behaviour on the other instruments

20 POE orbit residuals (2) Beacon change SPOT2 orbit RMS A ascending D descending T,H meteorological parameters for SPOT2 1.0 (35 days before beacon change) 3.0 (35 days after beacon change) A D A D small improvement?

Ascending : summer/winter contrast descending descending Influence of the mask

21 POE orbit residuals (3) Geographical effects Winter (min elev = 12 ) Summer, min elev = 8 ascending ascending All residuals (validated + eliminated) Ascending : summer/winter contrast descending descending Influence of the mask : - elimination around the NW area - complete pass eliminated? mm/s mm/s

22 Morning Kourou passes POE orbit residuals (4) Signatures of passes ex : Envisat, arc 147 (05/04/05 to 11/04/05) Evening Kourou passes residuals (mm/s) local hour local hour Signatures for both type of pass need an analysis of the measurement correction

23 Plan Power attenuations Signal losses POE orbit residuals Measurement corrections

24 Measurement corrections (1) Ionosphere variability effect on 2 GHz Doppler? mm/s mm/s Correction ionosphérique 2 GHz 2/12: sec 4/12/ s 5/12/ s Morning passes seconde (N2-Doppler-iono) 2/12: sec 4/12/ s 5/12/ s seconde mm/s mm/s Correction ionosphérique 3/12/ sec 4/12/ s 5/12/ s Evening passes seconde (N2-Doppler-iono) 3/12/ s 4/12/ s 5/12/ s seconde Doris/SPOT5 at Kourou : Fast fluctuations of both ionospheric correction and 2 GHz Doppler (scintillation effect?)

25 Measurement corrections (2) Contribution of the tropospheric effect at Kourou? 2,90 Allongements tropo (LOC) - tous satellites Total tropospheric correction (all satellites) 2,80 2,70 2,60 RMS de Guier en fonction la latitude nov 05) Guier RMS vs. Latitude (SPOT5, Nov. 05) 4,5E-03 2,50 2,40 2,30 4,0E-03 2,20 RMS Guier (Hz) 3,5E-03 3,0E-03 2,5E-03 2,0E-03 15/07/04 2,90 14/08/04 13/09/04 13/10/04 12/11/04 12/12/04 11/01/05 10/02/05 12/03/05 11/04/05 11/05/05 10/06/05 Allongements tropo (LOC) - tous satellites 10/07/05 09/08/05 08/09/05 Total tropospheric correction vs. local hour (all satellites) 08/10/05 07/11/05 2,80 1,5E ,70 Latitude 2,60 2,50 2,40 2,30 2,20 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:

26 Measurement corrections (3) Azimuthal variability of the troposphere near Kourou? Tropospheric correction grid : wet component (ex : 01/03/02 at 12h TU) -27 cm -45 cm 0 cm -33 cm Use of a non-symmetric elevation function? -37 cm -26 cm

27 Conclusions Beacon change : reception improvement, better orbit residuals Signal and residuals (Guier & POE) perturbations : Presence of a mask attenuations and losses, increase of residuals Seasonal effect of the reception quality (attenuations + losses) : Declining reception during winter and the evening Effect of the ionospheric scintillations

ELECTROMAGNETIC PROPAGATION (ALT, TEC)

ELECTROMAGNETIC PROPAGATION (ALT, TEC) N. Picot CNES, 18 Av Ed Belin, 31401 Toulouse, France Email : Nicolas.Picot@cnes.fr ABSTRACT For electromagnetic propagation, the ionosphere plays a key role. This