We report the role that the ambiguity function (AF) plays on the determination of signal to noise ratio (SNR) collected from meteor head echoes. Theoretical analysis shows that any measured meteor SNR exhibits temporal ripples whose shape is related to both the transmitted pulse envelope and the filter impulse response of the receiver. These theoretical findings are corroborated with (1) experimental meteor data recorded with Jicamarca 50 MHz radar (11.95 S, 76.87 W) and (2) simulated meteor data obtained by replicating the acquisition system of Jicamarca. A statistical analysis of the experimental meteor data reveals that at least 14% of the population collected each day at Jicamarca exhibits these ripples. On the remaining 86% of meteor events, the ripples cannot be distinguished due to noise, contamination from other sources of scattering (i.e., nonspecular echoes), and ensemble avera...

Radar observations typically employ periodic pulses to study any target. This scheme allows a simple processing of the data but the results frequently shows range or frequency aliasing. In order to solve this problem Uppala and Sahr [1] introduced the aperiodic technique (AT) in the radio science community. The AT is based on transmitting pulses at non uniform intervals and allows to study moderately overspread targets. Some equatorial Spread F (ESF) echoes belong to this category, particularly those from the topside. Using this idea Jicamarca Radio Observatory (JRO) has done a couple of experiments to study ESF echoes. Chau et al [2] used the Fast Fourier Transform (FFT) to compute spectra from those experiments and developed some criteria to remove clutter due to the aperiodic sequence. A second scheme of work was introduced by Hysell et al [3] and this scheme uses a Bayesian method to...

Diapositivas presentadas en: CEDAR Workshop 2009 del 28 de junio al 2 de julio de 2009 en Santa Fe, Nuevo México, USA.

In recent years, more and more radar systems with multiple-receiver antennas are being used to study the atmospheric and ionospheric irregularities with either interferometric and/or imaging configurations. In such systems, one of the major challenges is to know the phase offsets between the different receiver channels. Such phases are intrinsic to the system and are due to different cable lengths, filters, attenuators, amplifiers, antenna impedance, etc. Moreover, such phases change as function of time, on different time scales, depending on the specific installation. In this work, we present three approaches using natural targets (radio stars, meteor-head and meteor trail echoes) that allow either an absolute or relative phase calibration. In addition, we present the results of using an artificial source (radio beacon) for a continuous calibration that complements the previous approach...

Diapositivas presentadas en 2009 Joint Assembly. The Meeting of the Americas. 24-27 May 2009. Toronto, Ontario, Canada.

Diapositivas presentadas en The Meeting of the Americas, 2009 Joint Assembly, organizadas por la American Geophysical Union del 24 al 27 mayo de 2009 en Ontario, Canada.