telis progress meeting, oberpfaffenhofen, 3. december 2007 telis terahertz limb sounder
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TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Agenda9:30 Welcome, Status of Telis: Summary of IMK integration campaigns, mechanics,
electronics, software (M. Birk, G. Wagner)10:00 Status of DLR channel (N. Suttiwong)10:15 Status of SRON channel (G. de Lange, P. Yagoubov)10:30 Status of RAL channel (N.N.)10:45 Coffee break11:00 Radiometric accuracy: sideband ratio, autocorrelator (M. Birk)11:30 Time schedule before Teresina campaign (M. Birk)12:00 Scientific capabilities of TELIS: DLR channel (M. Birk), SRON channel (N.N.), RAL
channel (N.N.)12:45 Lunch14:00 Scout scientific goals (H. Oelhaf)14:15 Planning of Teresina campaign, tuning science with MIPAS team, discuss
measurement plan (all) 15:15 Planning of Kiruna campaign (all)15:30 Coffee break15:45 Funding, campaigns, etc. after Kiruna (all)16:15 TELIS on HALO (M. Birk)16:30 Spare time17:30 End of meeting
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Status after 2nd integration campaign
Successful integration, pointing, EMC, TV test
Problems
• Leak in He constant pressure control
• Rate gyro not functional
• Light switches not functional
• Calibration blackbody T sensors not functional
• Measurement time efficiency insufficient
• Radiometric accuracy not established
• Faulty power supply for autocorrelator
To be solved for test flight
To be solved for flight with scientific results
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Open issues and modifications
Mechanics
• Cabling between movable and static telescope parts
• Connector plate of autocorrelator unit modification
• Indium seals for flanges, heat exchange unit
• Radiation shield for telescope and cables
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Open issues and modifications
Electronics/cabling
• Line drivers for MORABA card digital outputs
• Ground cables for control lines
• New DC/DC box for autocorrelator unit from SRON
• 5V, 6A DC/DC converter for autocorrelator improved
• Safety circuit for 1.8 THz channel LO
• Filters for DC/DC converters in analogue and digital rack
• Suitable batteries for analogue rack
• Resistor network for gate Voltage
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Open issues and modifications
Software
• Implementation of SRON driver
• HEB current monitor for PC/104
• On-board backup
• Adaption of 8 Gbyte Flash ROMs
• TM/TC test in Toulouse, round 2
• UDP ?
Thermal design
• Iteration of radiator areas
• Coating of radiator areas
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Radiometric accuracy
• Requirement: 1% true radiance
• Investigation: Gas cell measurement of opaque lines
• Needed: Sideband ratio – all three receivers measure double sideband mode
• Exception: Two opaque lines from both sidebands superimposed at same IF frequency
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
LO=16,961751
150
170
190
210
230
250
270
290
310
330
4000 4200 4400 4600 4800 5000 5200
Frequency, MHz
Bri
gh
tnes
s T
emp
erat
ure
,K
17:PE=4 15:PE=0
DLR channel, methanol, red: PE attenuator, blue: no attenuator
• Peak intensity wrong, 15 K instead of 300 K
• 11.5% line intensity error
• At first attributed to non-linearity in IF chain
DLR Measurements August 2007
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
RFpower & ACS
0
2000
4000
6000
8000
10000
12000
14000
16000
50 100 150 200 250 300
Temp (from Themometer), K
ab
s P
ow
er
0
0,2
0,4
0,6
0,8
1
1,2
Po
wer
, mW
abs(ACS) RFpower Linear (RFpower) Linear (abs(ACS))
DLR measurements October 2007
The IF was found to be perfectly linear
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
SRON channel, OCS, blue: 0.17 mb, black: 10.46 mb
SRON channel, OCS, olive: 10.5 mb, red: 31.26 mb, green: 60.02 mb, blue: 104.12 mb, cyan: 60.02 mb
SRON measurements November 2007
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
SRON measurements• Line intensity error 25%
• Spectral shape garbled, artefacts present – more serious error than intensity scaling error
• Apparantly severe error only when:
•Spectral IF gain varies by more than 5dB?
•Broad line is present
• Autocorrelation and quantization correction of broad features numerically simulated --- should be no prinicipal problem for autocorrelator
• SRON is currently fixing IF problem
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Detected autocorrelator spectrum
SRON DLR
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
DLR measurement November2007
Measurement at 5 mb (green, 13 spectra averaged), 10 mb (red, 41 spectra)
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Conclusion on autocorrelator problems
• The severe error (artefacts, spectrum garbled) is not linked to broad lines
• Remaining line scaling error can be attributed to a lag 0 error
• Modelling has shown: Quantization error changes ratio of line contrast to noise floor
• Noise floor information in lag 0, line information in all lags
• Error propagation into calibrated scene leads to observed spectrum
• Correction may be feasible
Open questions:
• Chip-dependence of scaling error?
• How does the error depend on the autocalibration?
• How does the error depend on spectral shape?
• Why does autocorrelator not work for strongly varying IF gain + broad line
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Outlook for autocorrelator problems
• Noise source + synthesizer with ACS and spectrum analyzer
• OCS measurements after IF of SRON channel is fixed
• Excerpt of relevant data will be sent to Omnisys
• Other experts involved: Chalmers, SRON
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Sideband ratio determination
Sideband ratios may depend on• Microwindow• Frequency within microwindow• LO power• Mixer bias• In case of standing waves: outside pressure, temperature
Requirement for double sideband measurement• Fabry-Perots fringes reduced to percent level
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Two methods:
1. Gas cell measurements with sample/without sample with two different radiation sources behind cell
Requires a spectrometer without problemsRequires lines covering range of interest
2. Bruker measurements
Method established
Requirement: Overspill of antenna beam by Bruker AΩ
Current status
No sideband ratios for level 2 processing determined
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Sideband ratios for different LO and mixer bias settings
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Sideband ratio variations for different LO and mixer bias settings
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
First sideband ratio measurements of THz channel 30.11.2007
• Diplexer tuning not optimised
• Problems with Bruker
• Only tentative results
• Spectral sideband variations ca. 6%, possible Fabry-Perot with 23 cm spacing
• Coincides with distance diplexer – HEB rooftops
• Should go away for better diplexer tuning
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Sideband ratio THz channel, LO = 1839.75 GHz = 61.367 cm-1,
Pink: USB/LSB, red: USB, blue: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Updated time schedule
according to Progress Meeting 04.12.2007Nr. Work package/Milestone
1 SRON+DLR radiometric tests
2 Mechanic modifications
3 Electronic modifications
4 RAL integration
5 TM/TC test in Aire
6 Total system assembly and test
7 Antenna profile measurement
8 TV test
9 Flight rehearsal
10 Packing
11 Shipping
12 Flight preparation
13 Flight
14
15 All channels integrated and tested
16 Packing list ready
17 Travel to Teresina
18 End of Teresina Campaign
31.01.
31.03.
02.05.
15.06.
12.07 01.08 02.08 03.08 04.08 05.08 06.08 07.08 08.08
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Time schedule• RAL and SRON integration and radiometric characterisation measurements
have to be coordinated
• Time requirement for RAL channel integration unknown
• Radiometric characterisation for RAL channel open
• Decision about additional TV test
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Scientific capabilities of DLR 1.8 THz channelTransmittance, limb sounding 40 to 14 km, tropical. Water vmr 6.2 ppm @ 14 km, 4.0 ppm @15 km. Limb sounding barely feasible.
Transmittance, limb sounding 40 to 16 km, tropical. Water vmr 3.0 ppm @ 16 km, 2.9 ppm @17 km.
Polar conditions: 12 km barely
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Species Line center/GHz LO range/GHz Sideband Preferred
OH 1834.75 1829.35-1830.25 USB X
OH 1834.75 1839.75-1840.20 LSB
OH 1837.8 1842.70-1842.20 LSB X
OH 1837.8 1833.50-1833.60 USB
H2O 1766.2 1770.70-1771.00 LSB
H2O 1880.75 1876.55-1875.65 USB X
H2O 1800.5 1805.65-1804.65 LSB
H218O 1815.85 1820.05-1820.85 LSB X
H218O 1815.85 1810.05-1811.65 USB
H217O 1783.4 1788.35-1788.80 LSB
H217O 1840.15 1844.20-1844.35 LSB
H217O 1840.15 1834.70-1836.00 USB X
HDO 1818.5 1823.70-1824.30 LSB
HDO 1818.5 1813.80-1814.30 USB
HDO 1853.9 1858.10-1859.60 LSB X
HDO 1853.9 1849.10-1849.70 USB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
Species Line center/GHz LO range/GHz Sideband PreferredO18O 1875.04 1880.34-1880.74 LSB
O18O 1875.04 1870.04-1870.84 USB X
HO21805.5 1810.075-1810.125 LSB
HO21821.8 1826.45-1826.55 LSB
HO21821.8 1817.40-1817.70 USB X
HO21847.25 1842.68-1842.75 USB
CO 1841.36 1846.00-1846.10 LSB
CO 1841.36 1836.10-1836.56 USB XHCl 1873.40 1877.60-1878.40 LSB
HCl 1873.40 1868.15-1869.05 USB X
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
OH, 16 km tangent , white: DSB, blue: DSB-OH, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
OH, 40 km tangent , white: DSB, blue: DSB-OH, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
HDO, 16 km tangent , white: DSB, blue: DSB-H2O, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
HDO, 40 km tangent , white: DSB, blue: DSB-H2O, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
H217O, 16 km tangent , white: DSB, blue: DSB-H2O, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
H217O, 40 km tangent , white: DSB, blue: DSB-H2O, green: USB, red: LSB
TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007
• Funding for integration of TELIS on HALO available for 2008/2009
• Since ASUR integration uncertain, TELIS would be valuable candidate for POLSTRACC demo mission
• TELIS integration in belly pod
• Limb sounding? Scientific benefit not explored
• Above flight altitude vertical resolution 5-10 km
• Remote sensing of clouds
• Temperature profiling like MTP
TELIS on HALO
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