10.1117/2.1201108.003703 Heterogeneous transmission and parallel computing platform for remote sensing Yi Guo, Antonio Rius, Serni Rob` o, and Carles Ferrer A novel architecture promises a new approach to real-time data post- processing for advanced satellite-navigation systems. Global navigation satellite system reflectometry (GNSS-R) is a remote-sensing technique that receives and processes micro- wave signals that are reflected from various surfaces. The system is shown schematically in Figure 1(a). The global posi- tioning system open-loop differential real-time receiver (GOLD- RTR) instrument has been proposed as a complement to GNSS-R to gather global positioning system (GPS) satellite sig- nals after they have been reflected from surfaces such as sea, ice, and ground 1 and to extract useful information from them: see Figure 1(b). This configuration—called the GNSS-R scenario— was first proposed in 1993 by the European Space Agency (ESA) as a passive multistatic radar system for monitoring mesoscale ocean altimetry. The main and most innovative feature of GOLD- RTR is its computation and storage in real time of the complex- valued cross-correlation waveform (CC-WAV) between GPS L1-C/A (so-called legacy civilian navigation) signals and the reflection signals. The CC-WAV retrieves geophysical parame- ters over different types of surfaces, e.g., sea level and tides, ice roughness and thickness, and soil moisture and biomass. However, the growing number of satellite installations is mak- ing great demands on high-performance post-processing design for space-level instrumentation. Due to the intensive computa- tion required for CC-WAV and the amount of data that must be stored prior to downlinking, onboard real-time parallel process- ing has been suggested as a promising approach to GNSS-R post-processing systems. Previously, 2 we proposed reducing the link load between satellite and ground by integrating the CC- WAV for one second by incoherently adding (i.e., averaging) the different points of the surface from the reflected waveform and comparing the result with the corresponding direct signal. Here, Figure 1. (a) Global navigation satellite system reflectometry (GNSS- R) scenario. (b) The global positioning system open-loop differential real-time receiver (GOLD-RTR). (c) Schematic showing the inter- operation of the GOLD-RTR and the heterogeneous transmission and parallel computing platform (HTPCP). (d) Block diagram of the sys- tem. eth: Ethernet. JTAG: Joint test action group. LHCP: Left-hand cir- cularly polarized. RF: Radio frequency. RHCP: Right-hand circularly polarized. we describe a method of post-processing the CC-WAV on a space segment to lessen the data transmission load on the ground. In the past 10 years, dynamically reconfigurable field- programmable gate arrays (FPGAs) have proven well suited to parallel architectures because they incorporate several soft cores (i.e., open cores and embedded operating systems). Tak- ing into account time-to-market issues and rapid prototype de- velopment, a shared-memory symmetric multiprocessor (SMP) mounted with an embedded operating system would appear Continued on next page