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More Signal Intensity Dependency Tests at Yarragadee. Randall Carman EOS Space Systems / Moblas5. ILRS Technical Workshop - Eastbourne 2005. Introduction. - PowerPoint PPT Presentation
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More Signal Intensity More Signal Intensity Dependency Tests at YarragadeeDependency Tests at Yarragadee
Randall Carman
EOS Space Systems / Moblas5
ILRS Technical Workshop - Eastbourne 2005
IntroductionIntroduction
We have conducted experiments to try & determine the magnitude of ranging biases induced by receive energy variation in a multi-photon SLR system.
In particular we want to try and find any biases induced by satellite signature (Centre of Mass) effects.
ILRS Technical Workshop - Eastbourne 2005
Acquiring DataAcquiring Data
We use the receive path ND wheel to ensure Receive Energy continually varies throughout entire pass. This should eliminate elevation/predict induced biases.
Receive Intensity was maintained within normal system Dynamic Range.
In our previous attempt at high/low energy experiments (see Carman et al,2004), we didn’t allow for discriminator walk in our analysis.
To remedy this, an extended Calibration set was recorded for each pass, ensuring we had good data for the whole dynamic range of the pass. We then use this to generate a walk function.
Satellites targeted: Lageos 1&2, Ajisai, GFO-1, Stella, Starlette, Jason & Envisat.
Good Lageos 1&2 candidate passes rare. Sky conditions had to be perfect to get enough variation between weak and strong returns.
ILRS Technical Workshop - Eastbourne 2005
Pass Receive EnergyPass Receive Energy
ILRS Technical Workshop - Eastbourne 2005
Ajisai
0
200
400
600
800
1000
1200
0 500 1000 1500 2000
Return #
Re
ce
ive
En
erg
y (
mV
nS
)
Lageos-1
0
50
100
150
200
250
300
350
400
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Return #
Re
ce
ive
En
erg
y (
mV
nS
)
Receive energies are varied throughout pass to avoid biases which may be induced by elevation changes or predicts.
Process - AnalysisProcess - Analysis
Pass processed using regular np processor. Extract and plot calibration receive energy and residuals for each
data point. Produce discriminator walk function from calibration data. Extract and plot satellite residuals Vs Receive energy for each
data point. Edit outliers. Remove discriminator walk from satellite data by applying
previously calculated walk function.
ILRS Technical Workshop - Eastbourne 2005
Typical Calibration CurveTypical Calibration Curve
y = 0.000000000281773x 4 - 0.000000444460192x3 + 0.000298236026503x 2 - 0.089876131173947x + 8.115591062313750
-20
-15
-10
-5
0
5
10
15
20
25
0 100 200 300 400 500 600 700 800 900
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
ILRS Technical Workshop - Eastbourne 2005
Typical Receive energy Vs Single Shot Residual curve for an extended calibration set.
Resulting 4th order polynomial trend function is applied to satellite residuals
CFD Walk FunctionsCFD Walk Functions
ILRS Technical Workshop - Eastbourne 2005
Polynomial functions calculated from extended calibration sets.
-5
5
15
25
35
45
0 100 200 300 400 500 600 700 800 900 1000
Receive Energy
Res
idu
al (
mm
)
Lag1/2/Stella
Envisat
GFO/Jason
Ajisai
Starlette
ResultsResults
StellaStella
ILRS Technical Workshop - Eastbourne 2005
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800
Rx Energy (mVnS)
Res
idu
als
(mm
)
-30
-20
-10
0
10
20
30
0 100 200 300 400 500 600 700 800
Rx Energy (mVnS)
Res
idu
als
(mm
)
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
StarletteStarlette
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-40
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800 900
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
-40
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800 900
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
Lageos-1Lageos-1
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-40
-30
-20
-10
0
10
20
30
40
50
0 50 100 150 200 250 300 350 400
Rx Energy (mVnS)
Res
idu
als
(mm
)
-50
-40
-30
-20
-10
0
10
20
30
40
50
0 50 100 150 200 250 300 350 400
Rx Energy (mVnS)
Res
idu
als
(mm
)
Lageos-2Lageos-2
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-50
-40
-30
-20
-10
0
10
20
30
40
0 50 100 150 200 250 300
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
-50
-40
-30
-20
-10
0
10
20
30
40
0 50 100 150 200 250 300
Rx Energy (mVnS)
Res
idu
als
(mm
)
GFO-1GFO-1
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-30
-20
-10
0
10
20
30
0 100 200 300 400 500 600 700 800 900
Rx Energy (mVnS)
Res
idu
als
(mm
)
-30
-20
-10
0
10
20
30
0 100 200 300 400 500 600 700 800 900
Rx Energy (mVnS)
Res
idu
als
(mm
)
JasonJason
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-40
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800 900 1000
Rx Energy (mVnS)
Res
idua
ls (m
m)
-40
-30
-20
-10
0
10
20
30
40
50
0 100 200 300 400 500 600 700 800 900 1000
Rx Energy (mVnS)
Res
idu
als
(mm
)
EnvisatEnvisat
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800 900 1000
Rx Energy (mVnS)
Res
idu
als
(mm
)
-30
-20
-10
0
10
20
30
40
0 100 200 300 400 500 600 700 800 900 1000
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
AjisaiAjisai
ILRS Technical Workshop - Eastbourne 2005
Single Shot residuals Vs Receive Energy without Discriminator walk removed
With Discriminator walk removed
-50
-40
-30
-20
-10
0
10
20
30
40
50
0 100 200 300 400 500 600 700 800
Rx Energy (mVnS)
Re
sid
ua
ls (
mm
)
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
0 100 200 300 400 500 600 700 800
Rx Energy (mVnS)
Res
idu
als
(mm
)
DiscussionDiscussion
Although we will continue to take more experimental passes - it appears as though any biases induced by satellite signature are indeed small especially for the spherical satellites.
Some Satellite signature effect seems apparent for at least Ajisai. How many photons are in the lowest level returns (35 mVnS) ? Some
people suggest at least 3. How many in the high level? We are seeing variations with time of the floor level of receive energies.
The Integrator is probably inducing this +/-30 mVnS error. Maybe if we can eliminate this, we could see some finer effects.
The results do show how important it is to maintain as constant a receive energy throughout passes as possible to reduce biasing by Discriminator Walk.
At Yarragadee we should align the discriminators better for the the low return energies and restrict return energies above 800 mVnS during passes.
ILRS Technical Workshop - Eastbourne 2005
ReferencesReferences
Carman,Noyes & Otsubo: Centre of Mass Correction Issues: Determining Intensity Dependency at a Multi-photon (Moblas5) station. Proc. International Workshop on Laser Ranging, San Fernando,2004.
Otsubo & Appleby: Centre of Mass Correction Issues: Towards mm Ranging. Proc. International Workshop on Laser Ranging, San Fernando,2004.
ILRS Technical Workshop - Eastbourne 2005
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