Moving to kHz Ranging

Eastbourne, October 2005

- kHz Experiences in Graz- SLR 2000 Status & Issues- Herstmonceux kHz Status- Complete PC Board for kHz SLR- Others ?- Discussion, Questions, Plans …

kHz Ranging: Graz Experiences

Eastbourne, October 2005

2 Years Experience with the

Graz kHz SLR System

2 years kHz Ranging:

Fully operational since 2 years, day and night; All satellites - from Champ to GPS 35 / 36 – are tracked; Routinely 2000 Hz used (lower repetition rates would be

possible, but are never used ...); Laser System is running very stable;

Pump Diodes: Now 6000 hours, still perfect ... Results: NOT ONLY (big) increase in return numbers;

EVERYTHING has improved significantly: Stability; Single Shot RMS; Accuracy; Additional Outputs Results …

Eastbourne, October 2005

2 years kHz Ranging

Eastbourne, October 2005

Experiences in Graz (1):

kHz SLR gives lot of returns (million !) – even with J lasers ! kHz lasers are DPSS (Diode Pumped Solid State) units:

(... like changing from tubes to transistors ) They deliver very stable, very uniform pulses; They can deliver short pulses (10 ps in Graz); This results in 2-3 mm SS RMS:

For CAL AND for – some – satellites (Grace, Champ..)

kHz SLR Graz: Single Shot RMS GRACE A & B, 2003 - 2005

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

2003.0 2003.5 2004.0 2004.5 2005.0 2005.5

SS

RM

S [

mm

]

Grace AGrace B

kHz Ranging: Grace SS RMS

kHz Laser10 Hz Laser

2 years kHz Ranging

Experiences in Graz (2):

With kHz, you get not only more and better returns,

but also additional information:

You can „see“ single Retro-Reflectors; With up to 100 k pts/NP: Single-NP-statistics ??? You can „see“ satellite spin and measure its parameters !

Eastbourne, October 2005

Ajisai Spin Determination

Eastbourne, October 2005

AJISAI: Retro panels seen at

variable distances; AJISAI rotates (0.51 Hz); @ 10 Hz: Big Sat Signature;

@ kHz: Single Retro Motion

visible

kHz Ranging: AJISAI Spin

Eastbourne, October 2005

AJI26907 Daylight 300 k pts

Ajisai Spin Determination

Eastbourne, October 2005

AJISAI 10 secs of

full pass: 11 k rets

AJI12217/05: 10 secs of residuals

-15

-10

-5

0

5

10

15

64708 64710 64712 64714 64716 64718

Seconds-of-Day

Res

idua

ls [m

m]

Residuals [1-way mm]

Ajisai Spin Determination

Eastbourne, October 2005

AJISAI:

2.5 secs of full pass;

3 k rets;

Spin: 0.51 Hz

AJI12217/05: 2.5 secs of residuals

-15

-10

-5

0

5

10

15

64708.0 64708.5 64709.0 64709.5 64710.0 64710.5

Seconds-of-Day

Res

idua

ls [m

m]

Residuals [1-way mm]

kHz Calibrations: Differences

SLR Graz: Routine - Calibrations 2005;Each CAL: 10 000 Returns

-6

-4

-2

0

2

4

6

2005 2005.1 2005.2 2005.3 2005.4 2005.5 2005.6

Dif

fs b

etw

ee

n s

uc

ce

ss

ive

CA

LS

[m

m]

Successive CAL Diffs [mm]

kHz Valibrations: Single Shot RMS

SLR Graz: Routine - Calibrations 2003-2005;10 Hz: 500 Returns; kHz: 10 000 Returns

0.00.5

1.01.5

2.02.53.0

3.54.0

4.55.0

2003 2003.5 2004 2004.5 2005 2005.5

CA

L R

MS

[m

m]

CAL RMS [mm]

10 Hz 2 kHz

kHz Calibrations: Peak - Mean

SLR Graz: Routine - Calibrations 2003-2005;10 Hz: 500 Returns; kHz: 10 000 Returns / CAL

-4

-3

-2

-1

0

1

2

3

4

2003 2003.5 2004 2004.5 2005 2005.5

Pe

ak

min

us

Me

an

[m

m] CAL Peak minus Mean [mm]

kHz Ranging: Graz Experiences

Eastbourne, October 2005

High Orbit Satellites, e.g. GPS 35 / GPS 36: Difficult to track for most SLR stations; Low return quotes; Not many stations get daylight GPS returns …

kHz: Also advantages for GPS 35 / 36 Tracking: Acquisition is faster, easier with kHz laser; More returns / NP from GPS than with 10 Hz lasers; Day and night: Very similar results;

kHz Ranging: GPS 35/36

GPS-35:- Daylight Pass;

- 12 k pts remaining;

- Down to 47° Elev.

- 4.5 mm RMS

kHz Ranging: GPS with 400 J

GPS 35: Average # of Pts/NP in 200484

5

357

215

155

129

95 67 62 46 32 30 30 20 18 12 7 3

0200400600800

1000

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Riy

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kHz Ranging: Graz Experiences

Additional Information / all presentations of the kHz Workshop 2004 in

Graz available at:

http://khzslr.oeaw.ac.at/presentations.htm

Eastbourne, October 2005

kHz Ranging: Graz Experiences

Eastbourne, October 2005

Conclusion: The kHz Poem ....

Kilo-Hertz is lot of fun !

At least if all the work is done

It DOES make sense – you should NOT wait …

You should increase your firing rate !!!