Optimization of heterodyne observations using Allan variance measurements

Abstract

Abstract. Stability tests based on the Allan variance method have become a standard procedure for the evaluation of the quality of radio-astronomical instrumentation. They are very simple and simulate the situation when detecting weak signals buried in large noise fluctuations. For the special conditions during observations an outline of the basic properties of the Allan variance is given, and some guidelines how to interpret the results of the measurements are presented. Based on a rather simple mathematical treatment clear rules for observations in "Position-Switch", "Beam-" or "Frequency-Switch", "On-The-Fly-" and "Raster-Mapping" mode are derived. Also, a simple "rule of the thumb" for an estimate of the optimum timing for the observations is found. The analysis leads to a conclusive strategy how to plan radio-astronomical observations. Particularly for air-and space-borne observatories it is very important to determine, how the extremely precious observing time can be used with maximum efficiency. The analysis should help to increase the scientific yield in such cases significantly.

Estimation of Time Series Models via Robust Wavelet Variance

“…For example, it has been used for over 30 years as a standard routine measure of frequency stability in lasers (see Fukuda, Tachikawa, and Kinoshita (2003)) or atomic clocks (see Allan (1987)). More recently, the WV has also been used with optical sensors (see Kebabian, Herndon, and Freedman (2005)), various types of gas monitoring spectrometers (see Bowling, Sargent, Tanner, and Ehleringer (2003); Werle, Mücke, and Slemr (1993)), sonic anemometer-thermometers (see Loescher, Ocheltree, Tanner, Swiatek, Dano, Wong, Zimmerman, Campbell, Stock, Jacobsen et al (2005)), inertial sensors (see Guerrier (2009);El-Sheimy, Hou, and Niu (2008)), radio-astronomical instrumentation (see Schieder and Kramer (2001)). The WV was also used for example in Percival and Guttorp (1994) to analyse geophysics time series.…”

Compact Setup of a Tunable Heterodyne Spectrometer for Infrared Observations of Atmospheric Trace-Gases

“…The Allan variance method, a common procedure to investigate the accuracy of time and frequency standards [28], is used to demonstrate the radiometric decrease of the noise amplitude. The minimum of the Allan variance can be determined using a power law, where frequency drifts are proportional to τ β and the white noise contribution is proportional to 1 τ [29]. It can be written as:…”

Performance of a Low-Noise Test Facility for the SAFARI TES Bolometer Arrays

“…This particular detector had previously been characterized in SRON-Utrecht and also by Beyer et al in a low-background test facility [4]. To check the stability of the facility we measured the Allan variance [5,6] with the detector in the superconducting state and found a minimum at about 6 s. When the TES is in the superconducting state we see lines in the power spectrum, from radiofrequency interference and microphonic pickup, that disappear when the pulse-tube cooler is switched off. These are small compared with the current noise when the TES is biased on the transition and do not interfere with the measurement of the detector NEP (see Fig.…”