NASA Technical Reports Server (NTRS) 20110002991: SAD5 Stereo Correlation Line-Striping in an FPGA

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by  NASA Technical Reports Server (NTRS)

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
in less than 80 BRAM, 52k Slices on a Vir- be computed on the PowerPC 750 flight This work was done by Carlos Y. Villal-
tex 5LX330T, 25% and 24% of resources, computer. The work covered in the re- pando and Arin C. Morfopoulos of Caltech for
respectively. Using a 100-MHz clock, this port allows the stereo algorithm to run NASA’s Jet Propulsion Laboratory. Further in-
build would perform stereo at 39 Hz. on much larger images than before, and formation is contained in a TSP (see page 1).
Of particular interest to JPL is that using much less BRAM. This opens up The software used in this innovation is
there is a flight qualified version of the choices for a smaller flight FPGA (which available for commercial licensing. Please con-
Virtex 5: this could produce stereo re- saves power and space), or for other al- tact Daniel Broderick of the California Insti-
sults even for very large image sizes at 3 gorithms in addition to SAD5 to be run tute of Technology at [email protected].
orders of magnitude faster than could on the same FPGA. Refer to NPO-47245.
NASA Tech Briefs, January 2011 11