A programmable pulse-position- modulation (PPM) encoder has been designed for use in testing an optical communication link. The encoder includes a programmable state machine and an electronic code book that can be updated to accommodate different PPM coding schemes. The encoder includes a field-programmable gate array (FPGA) that is programmed to step through the stored state machine and code book and that drives a custom high-speed serializer circuit board that is capable of generating subnanosecond pulses. The stored state machine and code book can be updated by means of a simple text interface through the serial port of a personal computer.
This work was done by David Zhu and William Farr of Caltech for NASA’s Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics/Computers category.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
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Refer to NPO-41103, volume and number of this NASA Tech Briefs issue, and the page number.
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Programmable Pulse-Position-Modulation Encoder
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Overview
The document outlines the development and features of a Programmable Pulse-Position Modulation (PPM) Encoder created by NASA's Jet Propulsion Laboratory (JPL). This technology addresses the need for a flexible and efficient method to test optical communication links, particularly in the context of evolving coding schemes in aerospace applications.
The primary motivation for developing the PPM encoder stems from the necessity to facilitate high-speed space communication. Traditional methods lacked the adaptability required to keep pace with advancements in coding techniques. The solution presented involves a programmable state machine and a codebook, which allows for easy updates to the encoder's functionality.
At the core of the PPM encoder is a Field-Programmable Gate Array (FPGA) that is programmed to navigate through a stored state machine and codebook. This setup drives a custom high-speed serializer board capable of generating pulse widths in the sub-nanosecond range. The encoder can be updated via a simple text interface through a PC serial port, making it user-friendly and versatile.
The document also highlights the contributions of key individuals involved in the project, including David Q. Zhu and William H. Farr, who played significant roles in the construction, design, and testing of the encoder. The technology is still in the prototype stage, with ongoing development aimed at enhancing its speed and performance.
In terms of commercialization, the PPM encoder has potential applications in various markets, particularly in high-speed communication systems. The document notes that while prototype boards have been built and tested, further development is necessary to finalize the invention and explore its commercial viability.
The PPM encoder represents a significant advancement in optical communication technology, enabling more efficient testing and implementation of high-speed communication links in space exploration and other related fields. The document emphasizes the importance of this innovation for future NASA projects and its potential impact on aeronautical and space activities.
Overall, the Programmable Pulse-Position Modulation Encoder is a cutting-edge technology that exemplifies NASA's commitment to advancing aerospace communication capabilities, with implications for both governmental and commercial applications.
