SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Single, inexpensive system uses two identical circuits for simultaneous, bidirectional data transmission. Frequency response with currently available amplifiers is from dc to over 70 kHz.
The subcarrier phase recovery is analyzed for the bent-pipe mode of Space Shuttle detached-payload data transmission on the Tracking and Data Relay Satellite System (TDRSS) Ku-band return link. The high-power component of the subcarrier modulation is unrestored payload data, either at baseband or modulating another subcarrier. At the receiver a Costas loop recovers the subcarrier phase. To analyze its performance in the baseband case, we obtain the loop S-curve, the power spectral density of the equivalent noise process, and the loop phase error variance.
Information necessary for the operation and maintenance of the Model 600F Data Transmission Test Set is presented. A description is contained of the physical and functional characteristics; pertinent installation data; instructions for operating the equipment; general and detailed principles of operation; preventive and corrective maintenance procedures; and block, logic, and component layout diagrams of the equipment and its major component assemblies.
Data is communicated between redundant channels formatted in blocks having an initial command word followed by a destination code, starting address and a variable number of data words including a word count. The blocks are transmitted between each channel and all of the channels over cross-channel data links, each channel receiving the data blocks and determining the validity thereof by counting the number of data words received and comparing that number to the word count transmitted for that block. An interrupt signal indicative of invalidity of a block is provided in the event of a miscompare. A stop address is generated for each block received for storage at the start address. A memory address is generated for each valid word received for storage in sequence starting immediately after the start address. The next block received has its start address placed immediately at the end of the previously received block.
Here, this paper details the implementation of the digital pulse shaping subsystem within the Backbone Transmission Line Encoding (BTLE) driver, a low-power, long-distance on-chip data transmission solution designed in a 65 nm CMOS process. Digital pulse shaping is critical for minimizing inter-symbol interference (ISI) caused by bandwidth limitations of on-chip interconnects, especially in wafer-scale monolithic active pixel sensors (MAPS). A duobinary encoder coupled with a parallelized polyphase finite impulse response (FIR) filter is used for efficient shaping of the transmitted signal spectrum. This reconfigurable architecture achieves reliable 160 Mb/s data transfer over a 10 cm on-chip link, as validated by simulations demonstrating low power consumption (FoM 37.3 fJ/bit/mm of transmission line length) and effective ISI mitigation.
An 85 Mb/s modem/codec to operate in a 34 MHz C-band domestic satellite transponder at a system carrier to noise power ratio of 19.5 dB is discussed. Characteristics of a satellite channel and the approach adopted for the satellite data transmission modem/codec selection are discussed. Measured data and simulation results of the existing 50 Mbps link are compared and used to verify the simulation techniques. Various modulation schemes that were screened for the SDT are discussed and the simulated performance of two prime candidates, the 8 PSK and the SMSK/2 are given. The selection process that leads to the candidate codec techniques are documented and the technology of the modem/codec candidates is assessed. Costs of the modems and codecs are estimated.
Telemetry on-line monitoring, compression, and transmission system for manned space flight network
Following the success of the VLBI Space Observatory Program (VSOP), a next generation space VLBI mission (VSOP-2) is currently being planned. We expect the data rate of more than 1 Gbps to get more sensitivity. Here we will present: (1) How to sample the data (on board), including the radiation test results which show we can have the 10 Gbps sampler LSI which can use in space; (2) Possibility of the bit rate more than 1 Gbps to downlink the VLBI data. We studied the link budget for the wide band data transmission, and discussed the various ideas which can get more than 1 Gbps; and (3) What kind of VLBI tracking station and recording system will be expected for the VSOP-2 mission? We will present the idea of using normal radio telescopes as a tracking station, and also review the possibility of recording and processing at the tracking stations and correlators.
Scheme for coding and compressing data signals for transmission are compared by new analytical technique. Transmission rate of several schemes are plotted for direct comparison and evaluation.
The Ohio University Avionics Engineering Center is currently developing a fiber optic data bus transmission and reception system that could eventually replace copper cable connections in airplanes. The original form of the system will transmit information from an encoder to a transponder via a fiber optic cable. An altimeter and an altitude display are connected to a fiber optic transmitter by copper cable. The transmitter converts the altimetry data from nine bit parallel to serial form and send these data through a fiber optic cable to a receiver. The receiver converts the data using a cable similar to that used between the altimeter and display. The transmitting and receiving ends also include a display readout. After completion and ground testing of the data bus, the system will be tested in an airborne environment.
A task order was written by the High Resolution, High Frame Rate Video Technology (HHVT) project engineers to investigate data compression techniques that could be applied to the HHVT system, and both existing and planned downlink/uplink capabilities of the Space Shuttle and Space Station Freedom. The following tasks were included: (1) Investigate signal channel availability and determine both the maximum possible data rate and the average data rate; (2) Identify time blocks for HHVT video transmission assuming time sharing and interruptions in the communication links; (3) Determine the bit error rates to be expected; and (4) Define the transmit and receive interfaces. A summary chart of the data transmission capabilities for Tracking and Data Relay Satellite System (TDRSS), the Space Shuttle, Space Station Freedom, Spacelab, and USLab are also presented.
Very high frequency-to-microwave converter relay link for transmitting telemetry data
NASA depends on advanced, ultra-sensitive photoreceivers and photodetectors to provide high-data communications and pinpoint image-detection and -recognition capabilities from great distances. In 2003, Epitaxial Technologies LLC was awarded a Small Business Innovation Research (SBIR) contract from Goddard Space Flight Center to address needs for advanced sensor components. Epitaxial developed a photoreciever capable of single proton sensitivity that is also smaller, lighter, and requires less power than its predecessor. This receiver operates in several wavelength ranges; will allow data rate transmissions in the terabit range; and will enhance Earth-based missions for remote sensing of crops and other natural resources, including applications for fluorescence and phosphorescence detection. Widespread military and civilian applications are anticipated, especially through enhancing fiber optic communications, laser imaging, and laser communications.
Distributed processing, fiber optics technology, and redundancy management in the aircraft environment are discussed. The project features the development of an angle-of-attack and sideslip data collection system hich features: (1) two independent microprocessor controlled data collection and calibration units; (2) transmission of data to the control system on a fiber optic data bus; and (3) software implemented error detection and recovery.
Apparatus for transmitting multiple channels of data across a rotating interface, such as between an antenna that rotates with respect to a platform, is described. Features of the apparatus include: (1) light emitter elements and light detector elements located on the two bodies that rotate relative to each other; (2) a lens for focusing light from each emitter element onto a corresponding detector element; and (3) an image rotating means which is turned as one of the objects rotates, to derotate the images of the emitter elements that are to be focused on the detector elements.
An assessment of the quantity of data processed by the system is discussed investigating the various methods for transmission within the system. Various methods of data storage are considered. It is concluded that the entire processing system should be located in White Sands, New Mexico.
A method of transmitting data packets, where randomness is added to the schedule. Universal broadcast schedules using encoding and randomization techniques are also discussed, together with optimal randomized schedules and an approximation algorithm for finding near-optimal schedules.
The data links established between the U.S. and Europe during the September 1985 International Cometary Explorer/Comet Giacobini-Zinner encounter are summarized. The Space Physics Analysis Network (SPAN), which is a link between U.S. universities, research institutes and NASA centers, was responsible for the rapid dissemination and analysis of the data obtained from the encounter. The network was then linked across the Atlantic to support investigators involved in a European experiment on board the spacecraft. It is concluded that SPAN provided ESA personnel with a unique opportunity to experience near-real-time data acquisition. The data transfer was performed successfully, and the experience gained proved useful in assessing ESA's needs for future participation in scientific international networking.