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N. Shirbacheh

Bio: N. Shirbacheh is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Signal processing & Interface (computing). The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Papers
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Proceedings ArticleDOI
09 Mar 2002
TL;DR: A testbed for evaluation of general-purpose digital signal processors in earth-orbiting radar scatterometers is discussed, and performance of the DSP subsystem was evaluated in terms of measured vs. theoretical execution speed, timing accuracy, power consumption, and computational accuracy.
Abstract: A testbed for evaluation of general-purpose digital signal processors in earth-orbiting radar scatterometers is discussed. Because general purpose DSP represents a departure from previous radar signal processing techniques used on scatterometers, there was a need to demonstrate key elements of the system to verify feasibility for potential future scatterometer instruments. Construction of the testbed also facilitated identification of an appropriate software development environment and the skills mix necessary to perform the work. A testbed was constructed with three Astrium MCMDSPs, based on the Temic TSC 21020 general purpose DSP. Commercial data conversion hardware and high-speed serial communication hardware was interfaced to the MCMDSPs to allow demonstration of the key interfaces between subsystem elements: DSP program loading, synchronization and communication between multiple DSPs, interface to the scatterometer radio frequency subsystem, commanding, and science data delivery to the instrument data handling subsystem. A baseline set of requirements for the radar signal processing subsystem was established. From these requirements, signal processing algorithms such as digital filters and FFTs were developed using a combination of standard library functions and custom software. A software framework was developed to coordinate execution of the periodic signal acquisition and processing routines with asynchronous commanding and timekeeping functions. Emphasis was placed on developing modular software that would be applicable to a number of potential future instruments. Performance of the DSP subsystem was evaluated in terms of measured vs. theoretical execution speed, timing accuracy, power consumption, and computational accuracy.

2 citations


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Proceedings ArticleDOI
25 Jul 2010
TL;DR: An on-board signal processing subsystem of a spaceborne rotating fan-beam scatterometer in China returned signal after downconversion to intermediate frequency and the coefficients of the expression of Kpc are presented.
Abstract: This paper introduces an on-board signal processing subsystem of a spaceborne rotating fan-beam scatterometer in China. The subsystem processes returned signal after downconversion to intermediate frequency. To reduce the data stream downlinked from the satellite, the final data bins are summed into 34 energy slices, each with a range resolution of 10 km. Then a simulation process is adopted to analyze the Doppler effects due to the motion of the spacecraft, and to generate the Doppler compensation table and the bin summation table. This method is also used to analyze the measurement variance K pc of each detected slice. Finally, the coefficients of the expression of K pc are presented.

2 citations

Proceedings Article
09 Mar 2002
TL;DR: Results are presented on development issues surrounding the use of SpaceWire in this environment, from physical layer implementation (cables, connectors, LVDS drivers) to diagnostic tools, driver firmware, and development methodology.
Abstract: The need for a high speed, reliable and easy to implement communication link has led to the development of a space flight oriented version of IEEE 1355 called SpaceWire. SpaceWire is based on high-speed (200 Mbps) serial point-to-point links using Low Voltage Differential Signaling (LVDS). SpaceWIre has provisions for routing messages between a large network of processors, using wormhole routing for low overhead and latency. {additionally, there are available space qualified hybrids, which provide the Link layer to the user's bus}. A test bed of multiple digital signal processor breadboards, demonstrating the ability to meet signal processing requirements for an orbiting scatterometer has been implemented using three Astrium MCM-DSPs, each breadboard consists of a Multi Chip Module (MCM) that combines a space qualified Digital Signal Processor and peripherals, including IEEE-1355 links. With the addition of appropriate physical layer interfaces and software on the DSP, the SpaceWire link is used to communicate between processors on the test bed, e.g. sending timing references, commands, status, and science data among the processors. Results are presented on development issues surrounding the use of SpaceWire in this environment, from physical layer implementation (cables, connectors, LVDS drivers) to diagnostic tools, driver firmware, and development methodology. The tools, methods, and hardware, software challenges and preliminary performance are investigated and discussed.

1 citations