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This Defense Intelligence Reference Document, DIA-08-1004-005, is dated 6 April 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications program. It reviews proposed laboratory generators and detectors for high-frequency gravitational waves. It favors a piezoelectric approach for proof-of-concept tests, IR-excited molecules for an operational transmitter and the Li-Baker detector as the receiver. It estimates about 1.9 million bits per second over 7,000 km through the Earth and discusses timing standards and interplanetary navigation uses.
From the source:Release of 2026-09-18 Incident: 4/6/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines whether high-frequency gravitational waves could serve as a communications medium while avoiding the attenuation that limits radio-frequency systems. The report surveys proposed transmitter and detector concepts, argues that gravitational-wave communications could support secure point-to-point links, timing standards, and interplanetary navigation, and gives particular attention to laboratory generator concepts and the Li-Baker detector as possible building blocks for such a system. The document makes clear, however, that the entire concept depends on capabilities that had not been demonstrated in practice, including laboratory-scale generation and reliable detection of usable high-frequency gravitational-wave signals. It is an exploratory systems-oriented review built around a future communications concept.
“Harder”1 page
UNCLASSIFIED//&Olil OiiiilCI0L Llili QPIL¥ section below. For a 5 μsec acquire test time, the result is Tacq = 150 x 150 x 16 x 5 μsec= 1.8 seconds acquisition time. However, with effectively perfect knowledge of time, frequency, and hence also phase, there will on ly be one case to check, so result is Tacq = 1 x 1 x 1 x 5 μsec = 5 μsec acquisition time. This is essentially instantaneous for applications such as TCP/IP or VoIP. This will favorably impact the overall TDMA efficiency in that it speeds the claiming process to the point where an "always on" link can be replaced by a "link on demand." This is a savings of 25 to 50 percent in channel usage for VoIP and TCP/IP sessions over "always on." 3.3.3 The Impact of Phase Noise Improvements on Phase Shift Encoding The use of a universal HFGW FTS would also benefit the relative phase noise of all term inals, allowing for finer phase encoding. Phase noise limits the type of modulation and manner of encod ing that can be performed in phase space, commonly used for over the air telecommun ication systems . An HFGW FTS system could reduce phase noise by providing a frequency reference with outstanding stability. For example, moving from QPSK to 8PSK or 16-PSK im proves bandwidth efficiency by a factor of 2 to 4. The phase space improvement is summarized in Figure 21. Q Q (a) QPSK (b) Low Noise QPSK (c) Low Noise BPSK (d) Low Noise 16-PSK Figure 21. The Impact of Phase Noise Improvements on Phase Shift Encoding In the example of Figure 21 nominal performance allows on ly QPSK, but improved phase noise would allow higher density phase encoding. Data rate will scale linearly with encoding efficiency as shown in Equation ( 13): Data Rate = (BW/2) x (Coding Efficiency) x (FEC Rate)/ (PN Spreading Factor) (13) Coding efficiency will be a factor of 2 better when moving from QPSK to 8PSK, or a factor of 4 better when moving from QPSK to 16-PSK. This will translate directly into a linear increase in the allowable data rate that a given bandwidth can support. Put another way, a universal frequency time standard could quadruple over the air bandwidth efficiencies just by improving phase noise alone. Phase noise improvements would be limited only by the slight variations induced in the HFGW signal passing through the earth as described in Baker (2007). UNCLASSIFIED/ /FOR OiiiilCl.t.k HSI!! eflti 29
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Official release, from the pursue 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.