TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 TELIS TeraHertz Limb Sounder

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 Agenda 9:30 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 break 11:00 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 Lunch 14:00 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 break 15:45 Funding, campaigns, etc. after Kiruna (all) 16:15 TELIS on HALO (M. Birk) 16:30 Spare time 17:30 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 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 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: mb SRON channel, OCS, olive: 10.5 mb, red: mb, green: mb, blue: mb, cyan: 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 problems  Requires lines covering range of interest  2. Bruker measurements  Method established  Requirement: Overspill of antenna beam by Bruker A Ω 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 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 = GHz = cm -1, Pink: USB/LSB, red: USB, blue: LSB

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 Updated time schedule according to Progress Meeting

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 channel Transmittance, limb sounding 40 to 14 km, tropical. Water vmr km, 4.0 km. Limb sounding barely feasible. Transmittance, limb sounding 40 to 16 km, tropical. Water vmr km, 2.9 km. Polar conditions: 12 km barely

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 SpeciesLine center/GHzLO range/GHzSidebandPreferred OH USBX OH LSB OH LSBX OH USB H2OH2O LSB H2OH2O USBX H2OH2O LSB H 2 18 O LSBX H 2 18 O USB H 2 17 O LSB H 2 17 O LSB H 2 17 O USBX HDO LSB HDO USB HDO LSBX HDO USB

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 SpeciesLine center/GHzLO range/GHzSidebandPreferred O 18 O LSB O 18 O USBX HO LSB HO LSB HO USBX HO USB CO LSB CO USBX HCl LSB HCl USBX

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-H 2 O, green: USB, red: LSB

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 HDO, 40 km tangent, white: DSB, blue: DSB-H 2 O, green: USB, red: LSB

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 H 2 17 O, 16 km tangent, white: DSB, blue: DSB-H 2 O, green: USB, red: LSB

TELIS Progress Meeting, Oberpfaffenhofen, 3. December 2007 H 2 17 O, 40 km tangent, white: DSB, blue: DSB-H 2 O, 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