Communications

Protecting the Sky

This whitepaper provides insights into the use, specifications, and impact of Radio Controlled (RC) Unmanned Aerial Vehicles (commonly referred to as “drones”). UAVs intended for recreational use are increasingly being used for other (sometimes hostile) purposes. These include: observing/disturbing public events, spying in protected areas, smuggling contraband into prisons, endangering/threatening commercial air traffic, and entering restricted airspace. A technical approach for countering the threats posed by such drones is described, and includes: monitoring the spectrum for relevant signals, identification of frequency-agile RC signals, direction finding, and possible defensive countermeasures.

Posted in: White Papers, White Papers

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Confidence Intervals for the Bit Error Rate of Coded Communications Systems

A new method provides a robust, rigorous confidence interval on which communications performance and system risk may be determined. NASA’s Jet Propulsion Laboratory, Pasadena, California The bit error rate (BER) is a wellunderstood metric for measuring communications system performance. When a system is not amenable to analytical performance analysis, a Monte Carlo simulation is often used to determine the performance. In such simulations, it is necessary to compute a 95% (or other percent) confidence interval to establish the statistical significance of the simulation run, or to determine how long to run a simulation to achieve the desired accuracy.

Posted in: Briefs

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Final High-Fidelity Down-Conversion Source for Secure Communications Using On-Demand Single Photons

The basic idea is to array, cascade, or time multiplex the output from several parametric down-conversion sources. John H. Glenn Research Center, Cleveland, Ohio Secure communication over long distances requires robust encryption. While current encryption algorithms exist using classical methods, there are no unconditionally secure methods of distributing encryption keys classically. However, by exploiting the quantum nature of individual photons, quantum key distribution (QKD) can be proven as an unconditionally secure method for the distribution of encryption keys. Because QKD operates via the transmission and detection of single photons, there are major challenges for practical use in terms of both key generation rate and the maximum distance over which a secret key can be established.

Posted in: Briefs, TSP

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Space Telecommunications Radio System Memory Test Application

NASA’s Jet Propulsion Laboratory, Pasadena, California This software provides a portable, flexible memory testing application meeting the NASA Space Telecommunications Radio System (STRS) specification. As an STRS-compliant application, the tester application is portable to any STRS-compliant hardware/software platform. Thanks to configurable properties, the tester application can be adjusted for many different memory environments.

Posted in: Briefs

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Functional Enhancements to the FPGA Implementation of the Advanced Orbiting System Data Link Protocol

NASA’s Jet Propulsion Laboratory, Pasadena, California Dynamic frame sizing was added to the existing AOS Packet Service FPGA implementation. This capability provides in-flight system calibration functionality, allowing the spacecraft and ground station the means to optimize a communication link by dynamically adjusting the Advanced Orbiting System (AOS) transfer frame size.

Posted in: Briefs, TSP

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Communication System and Method Over High-Latency, Low-Bandwidth Networks

Lyndon B. Johnson Space Center, Houston, Texas In high-latency, low-bandwidth networks such as those employed when communicating with an extraterrestrial object via wireless communication over hundreds or thousands of miles, it may be difficult or expensive to communicate large quantities of information in a reliable manner. Each data stream that is transmitted may require error correcting, redundancy, or other bandwidth-heavy techniques to ensure the information received matches the information transmitted. This may often lead to a total reduction of communicated information, with little regard for the importance of the underlying data.

Posted in: Briefs

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CASH: Framework for Streamlined, Daily Updates

NASA’s Jet Propulsion Laboratory, Pasadena, California Secure, efficient, and effective communication is critical for the multinational Cassini mission to Saturn. Cassini teams share information through the use of internal Web pages. The challenge was to develop dynamic Web pages that did not require special understanding of HTML complexities and the implementation of complex Web server access controls.

Posted in: Briefs, TSP

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