NASA Technical Reports Server (NTRS) 20110002997: FPGA Sequencer for Radar Altimeter Applications

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by  NASA Technical Reports Server (NTRS)

Semiconductors & ICs
Interface Supports Multiple Broadcast Transceivers for
Flight Applications
NASA’s Jet Propulsion Laboratory, Pasadena, California
A wireless avionics interface provides strapping of data links. This greatly sim- the network, and then uses this health
a mechanism for managing multiple plifies the design of redundant flight information to make autonomous deci-
broadcast transceivers. This interface subsystems. The interface fully exploits sions for routing traffic through trans-
isolates the control logic required to the broadcast data link to determine the ceivers. Multiple selection strategies are
support multiple transceivers so that the health of other transceivers used to de- supported, like having an active trans-
flight application does not have to man- tect and isolate faults for fault recovery. ceiver with the secondary transceiver
age wireless transceivers. All of the logic The interface uses simplified control powered off except to send periodic
to select transceivers, detect transmitter logic, which can be implemented as an health status reports. Transceivers can
and receiver faults, and take auton - intellectual-property (IP) core in a field- operate in round-robin for load-sharing
omous recovery action is contained in programmable gate array (FPGA). and graceful degradation.
the interface, which is not restricted to The interface arbitrates the reception This work was done by Gary L. Block,
using wireless transceivers. Wired, wire- of inbound data traffic appearing on William D. Whitaker, James W. Dillon, James
less, and mixed transceiver technologies multiple receivers. It arbitrates the trans- P. Lux, and Mohammad Ahmad of Caltech for
are supported. mission of outbound traffic. This system NASA’s Jet Propulsion Laboratory. For more in-
This design’s use of broadcast data also monitors broadcast data traffic to formation, contact [email protected].
technology provides inherent cross- determine the health of transmitters in NPO-46317
FPGA Sequencer for Radar Altimeter Applications
NASA’s Jet Propulsion Laboratory, Pasadena, California
A sequencer for a radar altimeter pro- A RAM (random access memory) quire minor processing to become
vides accurate attitude information for a within the FPGA holds instructions for range and velocity.
reliable soft landing of the Mars Science up to 15 sets. For each set, timing is run, This technology is the heart of the
Laboratory (MSL). This is a field-pro- echoes are processed, and a comparison Terminal Descent Sensor, which is an in-
grammable-gate-array (FPGA)-only im - is made. If a target is seen, more detailed tegral part of the Entry Decent and
ple m entation. A table loaded externally processing is run on that set. If no target Landing system for MSL. In addition, it
into the FPGA controls timing, process- is seen, the next set is tried. is a strong candidate for manned land-
ing, and decision structures. Radar is When all sets have been run, the ings on Mars or the Moon.
memory-less and does not use previous FPGA terminates and waits for the next This work was done by Andrew C. Berkun,
acquisitions to assist in the current ac- 50-millisecond event. This setup simpli- Brian D. Pollard, and Curtis W. Chen of Cal-
quisition. All cycles complete in exactly fies testing and improves reliability. A tech for NASA’s Jet Propulsion Laboratory. For
50 milliseconds, regardless of range or single vertex chip does the work of an more information, contact [email protected].
whether a target was found. entire assembly. Output products re- NPO-46988
Miniature Sapphire Acoustic Resonator — MSAR
Q values as high as 108 may be achieved at room temperature.
NASA’s Jet Propulsion Laboratory, Pasadena, California
A room temperature sapphire Where quartz technology is very ma- more. As quartz oscillators are an es-
acoustics resonator incorporated into ture and shows a performance im- sential element of nearly all types of
an oscillator represents a possible op- provement of perhaps 1 dB/decade, frequency standards and reference sys-
portunity to improve on quartz ultra- these sapphire acoustic resonators tems, the success of MSAR would ad-
stable oscillator (USO) performance, when integrated with matured quartz vance the development of frequency
which has been a staple for NASA mis- electronics could achieve a frequency standards and systems for both ground-
sions since the inception of spaceflight. stability improvement of 10 dB or based and flight-based projects.
NASA Tech Briefs, January 2011 9