Documents / Report
This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) program, is dated 6 April 2010 and is part of a series of advanced technology reports produced in FY 2009. It reviews proposed laboratory generators and detectors of high-frequency gravitational waves for communications. It favors an infrared-excited molecules transmitter and the Li-Baker detector, estimating about 1.9 million bits per second over 7,000 km through the Earth. It also discusses timing standards and interplanetary navigation uses.
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DDl.1.2 Detailed design of brackets and fixtures for the internal equipment,
wiring, piping and through-wall connections: the general principles demonstrated
by existing Magnetic Resonance Imaging (MRI) system designs (for example, from
Siemens MRI, GE Healthcare, and others) will be followed to determine the most
compatible design of the internal equipment, wiring, piping and through-wall
connections for the HFGW detector. A cryostat or cryogenic containment vessel
supported inside the vacuum vessel will house the superconducting magnet assembly
necessary for the Li-Baker detector. Through-wall fittings and seals for copper leads
supplying the magnet and other internal apparatus will be needed. Design of brackets,
wiring, and piping of detector equipment will also be based upon input from the other
tasks.
DDl.1.3 Design of vacuum system: there are a large number of "off-the shelf"
Ultra-High Vacuum (UHV) equipment providers such as: Varian, Inc. (Lexington,
Massachusetts), Kimball Physics, Inc. (Wilton, New Hampshire), and Edwards High
Vacuum Ltd. (UK), amongst others. Those with capability for producing a system able
to evacuate the chamber to about 10-7Torr for the HFRGW detector will be approached
to undertake a detailed specification.
DDl.1.4 Detailed design of size and shape of containment vessel: determination
of the containment vessel's precise dimensions will be based upon the final designs of
the equipment determined by the other tasks and will integrate all the specific sub-task
designs, resolving any conflicts between units.
DD1.2 Signal Processing
Design of the recording apparatus hardware and software development that will be
needed to handle merging the two receiver inputs over an averaging period of up to
1,000s: Dr. R. ML Baker (TSC), G.V. Stephenson (TSC). This will require the
conceptual design of digitizing hardware and software to handle the data gathered,
including the combination of multiple receiver signals, the use of delay histograms,
statistical filtering techniques, and the study of false alarm pitfalls in non-linear signal
processing. There is much overlap with this area and DDl.5, the design of the detection
receivers. The expected GW signal structure must be characterized to optimize the
matched filtering needed. The definition of a detection event is the foremost
consideration, and will be studied both in terms of the threshold level and in terms of
the statistics of exceeding that level. Expected signal to noise enhancements
("processing gain") will be investigated for various filtering and processing options, and
the effect of the Q-factor inherent in the detection apparatus will be included in this
area of the investigation. Linear processing techniques such as multiple receiver
combination and delay histogram searches will be studied, and nonlinear signal
processing will also be considered, including its effect on detectability, as well as its
effect on false alarm generation. This task includes the selection of the best computing
and digitizing recorder platforms for the signal-processing needed. Also under this task
is an investigation of whether magnetic field modulation can be used to advantage in
this detector. Any scattered BPF does not depend upon the applied magnetic field or on
the GW. Therefore, the wanted PPF can be "labeled" by varying the applied (nominally
static) magnetic field in some way. A common technique in magnetic resonance
experiments is to use field modulation coils that superimpose upon the constant applied
magnetic field a time-varying component at low frequency (for example, around 5GHz
but asynchronous with the commercial power supply frequency). As a result, the PPF is
46
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 57 pages are in the text index: search them above, or from the library's search.