MAMBO PRE-LAUNCH CALIBRATION CONSIDERATIONS S. Gulkis Paris Meeting February 4-6, 2002

CALIBRATION OVERVIEW FOUR LEVEL WORK BREAKDOWN RADIOMETRIC CALIBRATION SPECTRAL CALIBRATION TELESCOPE PARAMETERS BORESIGHT AND MIRROR POSITIONS

RADIOMETRIC CALIBRATION Requirement brightness temperature between space and atmosphere known to within 1% (3) or noise level RMS sensitivity less than 1 K in 1 sec Calibration budget considerations Optical system Emissivity and temperature knowledge of calibration target System linearity Gain stability (Alan variance) Sideband ratio (calibration target and mirror alignment covered later) Performance measurements System temperature Bandwidth

SPECTRAL CALIBRATION Requirement Spectral budget considerations Frequency knowledge to 1 m/sec - f/f < 1.0/3e8 = 3.3 e (-9) Frequency stability to 3.16 m/sec - f/f < 3.16/3e8 = 1 e (-8) Spectral response of filters /relative gain of spectral channels to 1% Knowledge of sideband ratio to TBD % Spectral budget considerations USO and frequency synthesizers Frequency response of spectrum analysers and filters Including stability Sideband responses /rejection Temperature suceptabilities

Wind Noise due to Frequency Jitter Requirement Frequency jitter shall produce an error less than .5 m/sec at 10 m/sec Implication for frequency stability f/f < 3.16/3e8 = 1 e (-8) Derivation |xm -xt| < 0.5 xm = measured wind speed = √(xt2 +x2) xt = true wind speed = 10 m/sec; x = freq. jitter (x/xt)2 = 2 (0.5)/xt x(rms) = 3.16 m/sec at xt = 10 m/sec Corresponds to 100 kHz at 10 Mhz √(102 +3.162)= 10.5

Telescope Parameters Requirements HPBW TBD Main beam efficiency >> 0.9 TBD Sidelobe levels >> -30 db TBD

BORESIGHT AND MIRROR POSITIONS Requirements Boresight direction shall known to within 0.2 HPBW and aligned with known WRT SC axis to within xxx Boresight stability shall be within 0.05 HPBW Considerations Scan mechanism position, repeatability and jitter S/C Stability