NASA Technical Reports Server (NTRS) 20110003009: Miniature Sapphire Acoustic Resonator - MSAR

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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
Current quartz oscillator technology has not been previously tested for mounting configuration will need atten-
is limited by quartz mechanical Q. With acoustic modes. tion. The effects of these parameters will
a possible improvement of more than This initial Q measurement and excita- be calculated and folded into the res-
×10 Q with sapphire acoustic modes, the tion demonstration can be viewed similar onator design. It is envisioned that the
stability limit of current quartz oscilla- to a transducer converting electrical en- initial test configuration would allow for
tors may be improved tenfold, to 10–14at ergy to mechanical energy and back. movable electrodes to check gap spacing
1 second. The electromagnetic modes of Such an electrostatic tweeter type excita- dependency and verify the input imped-
sapphire that were previously developed tion of a mechanical resonator will be ance prediction.
at JPL require cryogenic temperatures tested at 5 MHz. Finite element calcula- Quartz oscillators are key components
to achieve the high Q levels needed to tion will be applied to resonator design in nearly all ground- and space-based
achieve this stability level. However sap- for the desired resonator frequency and communication, tracking, and radio sci-
phire’s acoustic modes, which have not optimum configuration. The experiment ence applications. They play a key role
been used before in a high-stability oscil- consists of the sapphire resonator sand- as local oscillators for atomic frequency
lator, indicate the required Q values (as wiched between parallel electrodes. A standards and serve as flywheel oscilla-
high as Q = 108) may be achieved at DC+AC voltage can be applied to gener- tors or to improve phase noise in high-
room temperature in the kHz range. ate a force to act on a sapphire resonator. performance frequency and timing dis-
Even though sapphire is not piezoelec- With the frequency of the AC voltage tribution systems. With ultra-stable per-
tric, such a high Q should allow electro- tuned to the sapphire resonator fre- formance from one to three seconds, an
static excitation of the acoustic modes quency, a resonant condition occurs and Earth-orbit or moon-based MSAR can
with a combination of DC and AC volt- the sapphire Q can be measured with a enhance available performance options
ages across a small sapphire disk (≈ l mm high-frequency impedance analyzer. for spacecraft due to elimination of at-
thick). The first evaluations under this To achieve high Q values, many exper- mospheric path degradation.
task will test predictions of an estimated imental factors such as vacuum seal, gas This work was done by Rabi T. Wang and
input impedance of 10 kilohms at Q = damping effects, charge buildup on the Robert L. Tjoelker of Caltech for NASA’s Jet
108, and explore the Q values that can sapphire surface, heat dissipation, sap- Propulsion Laboratory For more information,
be realized in a smaller resonator, which phire anchoring, and the sapphire contact [email protected]. NPO-47343
Process-Hardened, Multi-Analyte Sensor for Characterizing
Rocket Plume Constituents
Stennis Space Center, Mississippi
A multi-analyte sensor was developed isopropanol, and ethylene from a single of a fiber bundle allows placement of
that enables simultaneous detection of measurement. the opto-electronic readout device at a
rocket engine combustion-product mole- The use of pin-printing technology place remote from the test stand. The
cules in a launch-vehicle ground test enables high-volume fabrication of the sensors are rugged for operation in
stand. The sensor was developed using a sensor chip, which will ultimately elimi- harsh environments.
pin-printing method by incorporating nate the need for individual sensor cali- This work was done by Kisholoy Goswami
multiple sensor elements on a single bration since many identical sensors are for Stennis Space Center. For more informa-
chip. It demonstrated accurate and sensi- made in one batch. Tests were per- tion, contact: Kisholoy Goswami, In-
tive detection of analytes such as carbon formed using a single-sensor chip at- noSense, LLC; (310) 530-2011. SSC-
dioxide, carbon monoxide, kerosene, tached to a fiber-optic bundle. The use 00348
SAD5 Stereo Correlation Line-Striping in an FPGA
NASA’s Jet Propulsion Laboratory, Pasadena, California
High precision SAD5 stereo computa- was developed to trade latency for would in the previous design be an effec-
tions can be performed in an FPGA BRAM by sub-windowing the image ver- tive 4× of BRAM usage: 2× for line width,
(field-programmable gate array) at tically into overlapping strips and stitch- 2× again for disparity search range.
much higher speeds than possible in a ing the outputs together to create a sin- The minimum strip size is twice the
conventional CPU (central processing gle continuous disparity output. search range, and will produce an out-
unit), but this uses large amounts of In stereo, the general rule of thumb is put strip width equal to the disparity
FPGA resources that scale with image that the disparity search range must be search range. So assuming a disparity
size. Of the two key resources in an 1/10 the image size. In the new algo- search range of 1/10 image width, 10 se-
FPGA, Slices and BRAM (block RAM), rithm, BRAM usage scales linearly with quential runs of the minimum strip size
Slices scale linearly in the new algorithm disparity search range and scales again would produce a full output image.
with image size, and BRAM scales qua- linearly with line width. So a doubling This approach allowed the innovators
dratically with image size. An approach of image size, say from 640 to 1,280, to fit 1280×960 wide SAD5 stereo disparity
10 NASA Tech Briefs, January 2011