OVERVIEW OF THE ANOMALIES AT THE KOUROU ...Microsoft PowerPoint - IDS06_s2_Yaya_Kourou.ppt Author...

- 1 -IDS Workshop, Venice13-15 March 2006

OVERVIEW OF THE ANOMALIESAT THE KOUROU BEACON SITE

Ph. Yaya, H. Capdeville, B. Frayssinet,B. Nhun-Fat, J.-J. Valette, L. Soudarin

CLS, Collecte Localisation Satellites, France

contact : [email protected]


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


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


Kourou : Taux de mesures traitées POE SPOT5

35%40%45%50%55%60%65%70%75%80%85%90%

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

mm

/s

kourou réseau entier

Some examplesR M S G u ie r s t a t io n ( S p o t 5 , n o v 0 5 )

1 , 0 E - 0 3

1 , 5 E - 0 3

2 , 0 E - 0 3

2 , 5 E - 0 3

3 , 0 E - 0 3

3 , 5 E - 0 3

4 , 0 E - 0 3

ADEB

RIPB

SPJB

THUB

STJB

SCRB

ME T

BHE

MB

SYPB

SANB

YAS B

ROTB

SAKB

REUB

BEM

BKE

SBYE

LBM

SPB

HBLB

NOW

BM

ATB

FAIB

SODB

JIUB

KOLB

MAL

BCR

OB

D IO

ACA

DB

C ICB

PDM

BM

ORB

TLHA

FUTB

MIA

BM

ANB

EAS B

TRIB

EVEB

REZB

L IBB

PAQ

BSA

LBAS

DBKR

VB

K IUB

KRVB

Kourou : RMS d'orbite POE SPOT5

0,350,400,450,500,550,600,650,700,750,80

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

mm

/s

kourou réseau entier

Rate of validatedmeasurementfor SPOT5 POE(August 03 July 05)

Orbit RMSof SPOT5 POE(August 03 July 05)

Guier RMSof SPOT5 POE(Nov. 05)

90%

35%

4.E-03

1.E-03


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 lossesDEF : 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)


Plan

• Power attenuations• Signal losses• POE orbit résiduals• Measurement correction


Power attenuation (1)Comparison of the received power levels

400 MHz better received than 2 GHz

Only D2 on the 400 MHz channel has the expected level

Mean values of the power attenuations (low-pass filter)


Power attenuation (2)Seasonal effect

Mean over 500 measurements sliding windowof the power attenuation for ENVISAT

Beginning of Nov. 2004 :change of beacon type 1.0 3.0

Std dev. over 500 measurements sliding window of the power attenuation for ENVISAT

More dispersion frome October to March


Power attenuation (3)Local hour effect

Abnormal situations during the evening :

- more dispersion

- some very low levels

- some high levels

Same behaviour for the other DORIS instruments

Morning passes (descending)

Evening passes (ascending)

Power attenuation for SPOT4(all passes Oct. 04 – Oct. 05)


Power attenuation (4)Geographical effect

Winter (min elev = 12°) Summer (min elev = 8°)

Presence of aninterference source (mask?)

- 20 dB and more

- N.W. from Kourou

- Persistent all the year

- Seen on all missions

# More fluctuations during winter

# Good 400 MHz reception on a western area

# Weak 2 GHz reception circle at high elevation

0 +10 dB-20 -10 0 +10 dB-20 -10

2 GHz 2 GHz

400 MHz 400 MHz


Plan

• Power attenuations• Signal losses• POE orbit residuals• Measurement corrections


Signal losses (1)Seasonal effect

- More losses from Nov. to March on the 400 MHz channel

- The same for the other missions

400 MHz

2 GHz

15 days signal losses on SPOT5Oct. 04 – Nov. 05


Signal losses (2)Local hour effect

- Evening passes

- Same for the other missions

- Jason : 2GHz losses whatever the local time constant presence of the interference source

Signal losses on SPOT5 vs. local hour


Signal losses (3)Geographical effect

(SPOT4 similar to SPOT2)

2 GHz 2 GHz

400 MHz 400 MHz


Signal losses (4)Geographical effect

400 MHz

2 GHz

400 MHz

2 GHz400 MHz more affected

The interfered area affects only the 2GHz losses

Heliosynchronous sat. : losses only on the ascending passes (evening)

Ascending passes with high elevation : less affected

Signal losses on ENVISAT (Oct. 04 – Oct.05) Signal losses on JASON (Oct. 04 – Oct.05)


The guilty interference source

Antenna of the DORIS beacon

Reception antenna of the CNES2GHz network

MASK


Comparison with GPS reception

The phenomenon is more important on the evening AND from October to March

IONOSPHERIC SCINTILLATIONS

L2 measurement losses of lock

Scintillation indices (empirical, [0-1], based on the phase fluctuations, same for both Kourou receiver)

Local hour

0h 12h 0h6h 18h0

1.5

3


Plan



POE orbit residuals (1)Comparison Kourou/DORIS network

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

SPOT2 monthly RMS : influence of latitude

Kourouequatorial latitudes (|λ|15°)

M: ascending (“montants”)D: descending


POE orbit residuals (2)Beacon change

small improvement ?

SPOT2 orbit RMSA ascending D descending

1.0(35 days beforebeacon change)

3.0(35 days after

beacon change)

A AD D

T,H meteorological parameters for SPOT2


POE orbit residuals (3)Geographical effects

Winter (min elev = 12°) Summer, min elev = 8°

All residuals(validated + eliminated)

Ascending : summer/winter contrast

Influence of the mask :- elimination around the NW area- complete pass eliminated ?

-3 +3 mm/s -3 +3 mm/s

ascending

descending

ascending

descending


POE orbit residuals (4)Signatures of passesex : Envisat, arc 147 (05/04/05 to 11/04/05)

local hour local hour

resi

dual

s (m

m/s

)

Morning Kourou passes Evening Kourou passes

Signatures for both type of passneed an analysis of the measurement correction


Plan



Measurement corrections (1)Ionosphere variability – effect on 2 GHz Doppler?

Correction ionosphérique 2 GHz

-50-40-30-20-10

01020304050

0 100 200 300 400 500 600

seconde

mm

/s

2/12:05 51749 sec 4/12/05 49000 s 5/12/05 48000 s

Correction ionosphérique

-50-40-30-20-10

01020304050

0 100 200 300 400 500 600

seconde

mm/

s

3/12/05 5100 sec 4/12/05 4000 s 5/12/05 8965 s

(N2-Doppler-iono)

-50-40-30-20-10

01020304050

0 100 200 300 400 500 600

seconde

mm/s

2/12:05 51749 sec 4/12/05 49000 s 5/12/05 48000 s

(N2-Doppler-iono)

-50

-40

-30

-20

-10

0

10

20

30

40

50

0 100 200 300 400 500 600

seconde

mm/s

3/12/05 5100 s 4/12/05 4000 s 5/12/05 8965 s

Doris/SPOT5 at Kourou :

Fast fluctuations of both ionospheric correction and 2 GHz Doppler (scintillation effect ?)

Morning passes Evening passes


Measurement corrections (2)Contribution of the tropospheric effect at Kourou?

RMS de Guier en fonction de la latitude (SPOT5 nov 05)

1,5E-03

2,0E-03

2,5E-03

3,0E-03

3,5E-03

4,0E-03

4,5E-03

0 10 20 30 40 50 60 70 80 90

Latitude

RMS

Gui

er (H

z)

Allongements tropo (LOC) - tous satellites

2,20

2,30

2,40

2,50

2,60

2,70

2,80

2,90

15/07

/04

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

10/07

/05

09/08

/05

08/09

/05

08/10

/05

07/11

/05

Allongements tropo (LOC) - tous satellites

2,20

2,30

2,40

2,50

2,60

2,70

2,80

2,90

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 0:0

0

Total tropospheric correction (all satellites)

Guier RMS vs. Latitude (SPOT5, Nov. 05)

Total tropospheric correction vs. local hour (all satellites)


Measurement corrections (3)Azimuthal variability of the troposphere near Kourou ?

-27 cm

-33 cm

Use of a non-symmetric elevation function ?

Tropospheric correction grid : wet component(ex : 01/03/02 at 12h TU)

-45 cm 0 cm

-37 cm -26 cm


Conclusions

• Beacon change 1.0 3.0 : 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 eveningEffect of the ionospheric scintillations

OVERVIEW OF THE ANOMALIES AT THE KOUROU ...Microsoft PowerPoint - IDS06_s2_Yaya_Kourou.ppt Author...

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