Radiometric CMB measurements need to be highly stable and this stability is best obtained with differential receivers. The residual 1/f noise in the differential output is strongly dependent on the radiometer input offset which can be cancelled using various balancing strategies. In this paper we discuss a software method implemented in the PLANCK-LFI pseudo-correlation receivers which uses a tunable gain modulation factor, r, in the sky-load difference. Numerical simulations and experimental data show how proper tuning of the parameter r ensures a very stable differential output with knee frequencies of the order of few mHz. Various approaches to calculate r using the radiometer total power data are discussed with some examples relevant to PLANCK-LFI. Although the paper focuses on pseudo-correlation receivers and the examples are relative to PLANCK-LFI, the proposed method and its analysis is general and can be applied to a large class of differential radiometric receivers.

Offset balancing in pseudo-correlation radiometers for CMB measurements / A. Mennella, M. Bersanelli, M. Seiffert, D. Kettle, N. Roddis, A. Wilkinson, P. Meinhold. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 0004-6361. - 410:3(2003), pp. 1089-1100.

Offset balancing in pseudo-correlation radiometers for CMB measurements

A. Mennella
Primo
;
M. Bersanelli
Secondo
;
2003

Abstract

Radiometric CMB measurements need to be highly stable and this stability is best obtained with differential receivers. The residual 1/f noise in the differential output is strongly dependent on the radiometer input offset which can be cancelled using various balancing strategies. In this paper we discuss a software method implemented in the PLANCK-LFI pseudo-correlation receivers which uses a tunable gain modulation factor, r, in the sky-load difference. Numerical simulations and experimental data show how proper tuning of the parameter r ensures a very stable differential output with knee frequencies of the order of few mHz. Various approaches to calculate r using the radiometer total power data are discussed with some examples relevant to PLANCK-LFI. Although the paper focuses on pseudo-correlation receivers and the examples are relative to PLANCK-LFI, the proposed method and its analysis is general and can be applied to a large class of differential radiometric receivers.
Cosmology: cosmic microwave background, observations; Instrumentation: detectors; Methods: analytical
Settore FIS/05 - Astronomia e Astrofisica
Settore FIS/01 - Fisica Sperimentale
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/198995
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