A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual- carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator.
This work was done by Stanley Butman, Edgar Satorius, and Peter Ilott 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 Information Sciences category. NPO-42910
This Brief includes a Technical Support Package (TSP).
Special Semaphore Scheme for UHF Spacecraft Communications
(reference NPO-42910) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) detailing a new semaphore signaling scheme for UHF (Ultra High Frequency) spacecraft communications, identified by NTR Number 42910. This innovation is part of NASA Tech Briefs, which aim to disseminate aerospace-related developments that have broader technological, scientific, or commercial applications.
The special semaphore scheme is designed to improve communication efficiency and reliability for spacecraft operating in the UHF frequency range. UHF communications are critical for various space missions, including satellite operations, interplanetary missions, and communication with ground control. The new signaling scheme likely addresses challenges such as signal interference, bandwidth limitations, and the need for robust communication protocols in the harsh environment of space.
The document emphasizes the importance of this innovation within the context of NASA's Commercial Technology Program, which seeks to make advancements in aerospace technology accessible for wider use. It encourages collaboration and partnerships through the NASA Innovative Partnerships Program, highlighting the potential for commercial applications of the technology developed.
Additionally, the Technical Support Package provides information on how to access further resources related to research and technology in this area through the NASA Scientific and Technical Information (STI) Program Office. This includes contact details for the NASA STI Help Desk, which can assist with inquiries related to the technical documentation and its applications.
The document also includes a notice regarding the proprietary nature of the information contained within, indicating that it may be subject to export control regulations. It clarifies that the United States Government, nor any individuals acting on its behalf, assumes liability for the use of the information provided, nor does it guarantee that such use will be free from privately owned rights.
In summary, the Technical Support Package outlines a significant advancement in UHF spacecraft communication technology, promoting its potential applications and encouraging further exploration and collaboration in the aerospace sector. This innovation represents a step forward in enhancing the capabilities of spacecraft communications, which is vital for the success of current and future space missions.
