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Proceedings with Extended Abstracts (single PDF file) - Radio ...

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Figure 3. Pulse Design Diagram to synchronize the BLT and ST Systems operating at thesame frequency.For our comparisons we have used hourly averaged data (consensus <strong>file</strong>s) for bothsystems. We have removed data when the SNR is below a given SNR Threshold (0 dB) andwhen outliers are present. In order to identify the outliers we calculate the median and standarddeviation per each height (continuously) for both modes. Those points that are over 1.5standard deviations are outliers. A similar approach has been used by Palo et al. [1995]. Afterwe obtained the averages for each mode, we combined them to obtain a <strong>single</strong> <strong>file</strong> from eachsite, i.e., in the case of Piura below 1.5 km data from the low mode is used, while above 1.5 kmdata from the high mode is used. At Porcuya, we have selected 2.5 km to be the border heightbetween the two modes.Pilot Balloons are launched at Piura almost everyday around 1600 local time, and as wecan see in a qualitative form (Figure 4-left), there is a good agreement between pilot balloonwinds and BLT winds. There is also very good agreement between the hourly winds obtained<strong>with</strong> the BLT and the ST system (Figure 4-right). Since the ST system has a poorer rangeresolution, we have convolved the BLT pro<strong>file</strong>s <strong>with</strong> a 1-km wide function for the comparison.Figure 4. Left: Pilot Balloon, BLT and ST qualitative comparison. Right: BLT vs. STComparison. Zonal Winds at Piura (April 2002). Correlation almost 1, between 2-4kmand 4-6km data.359

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