STAFF-SC / FGM Comparison I. Spectrograms comparison II. Average spectra comparison III. Wave Forms...

STAFF-SC / FGM Comparison

I. Spectrograms comparison

II. Average spectra comparison

III. Wave Forms comparison

IV. Noise Level

Conclusions

Cross_Calibration Workshop ESTEC, Noordwijk, 2-3 february 2006

P. Robert, CETP

A. Reminder on old comparisons (IC, London, February 2001)

B. New comparisons

P. Robert, Croos Cal WS, 2006-02-02, ESTEC

A. Old comparisons (IC, London, February 2001)

Original FGM High res. Files provided by M. Dunlop

Already STFF-FGM difference on perp. DC field

A.1 Spectrogram


A. Old comparisons (IC, London, February 2001)

Original FGM High res. Files provided by M. Dunlop

Sensitivity differs beyond 1 Hz

A.2 Average Spectra

Rather good agreementBetween STFF-FGM


B. New comparisons (February 2006)

All following result has done with FGM high res. DataProvided by FGM Dapclus software,

using cal tables downloaded from I.C.


I.1 Bx,By,Bz SC1I. Spectrograms comparison

OKRest of spin effect, OK


Position in space

18:0024:00 21:00

22:00

Tetrahedron size about 1200 km


I.2 Bz ALL S/C

OK

Pb !


I.3 Bperp ALL S/C

FGM

STAFF

1) STAFF < FGM,

2) STAFF Pb on S/C # 1

Sometimes up to 20%When strong DC field


I.3 Bperp SC1 and SC2

FGM

STAFF

2) STAFF Pb on S/C # 1

1) STAFF < FGM, Diff=1 nT or 16% on SC1, Diff=0.5 nT or 8% on SC2

Sometimes up to 20%When strong DC field


II. Average spectra comparison II.1 Bx,By,Bz SC1

STAFF FGM

Sensitivity loss

STAFF < FGM

Sensitivity loss

Fs

FsFs


II.2 Bz SC1

STAFF

FGM

II.2 Bz SC2

Some differences, as Bperp: Staff < FGM,

Best fit with SC2

Fs

FsFs

Parasite spikes


II.3 Bz All S/C

Fs

FsFs

Parasite spikesdifferent on each SC

Parasite spikes different between STAFF and FGM


III. Wave Forms comparison

III.1 Filtered Bx,By,Bz, Bperp SC1

STAFF bug, offset NE 0

STAFF/FGM : difference about 0.5 nT


III.2 ZOOM on Filtered Bx,By,Bz, SC1

Looks the same, butSTAFF < FGM

About 20% at 2 Hz


III.3 ZOOM on Filtered Bx,By,Bz, SC2

Best fit: About 5 %But not everywhere

16


IV. Background noise Level IV.1 Bx,By,Bz SC1

Starting Time 09:02:00.029

Starting Time 09:02:00.486

No reliable measurement

Fs

Fs Fs


IV. Background noise Level

IV.2 Bz SC1Fs

Fs

No hurried conclusion !Must be re-computed

For other events

FGM - STAFF-SC (from B. Grison)



PRELIMINARY CONCLUSION

- This work has be done too quickly: We have to take care with too fast conclusions

- Two basic problems has been identified:

a) Why perp DC. Field estimated from STAFF SC1 is less that SC2,3,4 ?

b) Why perp DC field estimated from STAFF is less than FGM measurement ?

. True for perp. DC field,

. But also true on the entire spectra,

. And also true on the filtered waveforms

We have to look on the 4 transfer functions, and carrefully study the onboard calibration

- A large amount of work remain to be done:

a) Study other cases, in other regions of spacein other epochs

With or without strong DC field

b) See if preliminary conclusions remains the same ; see also HBR mode

c) Introduce the new despin utility software, and restart all…

STAFF SC - SA (B. Grison)

10-1

100

101

102

103

104

10-12

10-10

10-8

10-6

10-4

10-2

100

102

104

10-1

100

101

102

103

10410

-10

10-8

10-6

10-4

10-2

100

102

104

106

10-1

100

101

102

103

10410

-10

10-8

10-6

10-4

10-2

100

102

104

106

FGM

STAFF-SC

STAFF-SA

f-2.5

SC 2-FGM/STAFF/EFW/SC+SA 2002/02/18 04:59:28-04:59:48

FGM/STAFF

nT2/Hz

EFW

(mV/m) 2/Hz

Hz

EFW

STAFF sensitivity

Fci=0.38Hz Flh=16Hz

FGM - STAFF - EFW (B. Grison)

STAFF-SC / FGM Comparison I. Spectrograms comparison II. Average spectra comparison III. Wave Forms...

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