The LandTrendr (LT) algorithm has been used widely for analysis of change in Landsat spectral time series data, but requires significant pre-processing, data management, and computational resources, and is only accessible to the community in a proprietary programming language (IDL). Here, we introduce LT for the Google Earth Engine (GEE) platform. The GEE platform simplifies pre-processing steps, allowing focus on the translation of the core temporal segmentation algorithm. Temporal segmentation involved a series of repeated random access calls to each pixel's time series, resulting in a set of breakpoints ("vertices") that bound straight-line segments. The translation of the algorithm into GEE included both transliteration and code analysis, resulting in improvement and logic error fixes. At six study areas representing diverse land cover types across the U.S., we conducted a direct comparison of the new LT-GEE code against the heritage code (LT-IDL). The algorithms agreed in most cases, and where disagreements occurred, they were largely attributable to logic error fixes in the code translation process. The practical impact of these changes is minimal, as shown by an example of forest disturbance mapping. We conclude that the LT-GEE algorithm represents a faithful translation of the LT code into a platform easily accessible by the broader user community.

Abstract:We demonstrate W-band wireless transmission over distances covering both indoor and building-to-building scenarios with a setup of reduced complexity in the RF domain, employing a passive wireless transmitter and envelope detection at the receiver.

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Resumo-A codificac ¸ão wavelet surgiu como uma técnica de codificac ¸ão de canal alternativa para minimizar os efeitos nocivos dos canais de comunicac ¸ão sem fio caracterizados pelo desvanecimento. Diferente de técnicas clássicas de codificac ¸ão, nas quais o ganho de codificac ¸ão surge através da adic ¸ão de uma redundância controlada a informac ¸ão, a robustez conseguida pela codificac ¸ão wavelet contra os efeitos do desvanecimento ocorre em func ¸ão de uma diversidade temporal gerada sobre a informac ¸ão transmitida. Até o momento, o desempenho da codificac ¸ão wavelet foi investigado apenas em canais de comunicac ¸ão sujeito a desvanecimento plano variante no tempo. Este trabalho avalia o desempenho da codificac ¸ão wavelet, em termos de probabilidade de erro de bit, sobre canais de comunicac ¸ão com desvanecimento Rayleigh variante no tempo e seletivo em frequência. Através de simulac ¸ão computacional, apresenta-se neste trabalho resultados numéricos que demonstram a eficiência dessa técnica no combate à interferência entre símbolos, característica destes cenários de comunicac ¸ão.

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