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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.
UNCLASSIFIED//&OR Oii&ICI0L Ll&li QPIL¥ Signal to noise ratios (SNR's) at the transmitter and at the receiver must be calculated to support a communications link design. Predicted SNR Predicted SNR Components at Link Components at the Transmitter Loss the Receiver rSignal Noise GW Sourc Noise ------ GW Xmit Signal 1/R2 Loss GW Antenna & Receiver Noise i EM to GW/'-,----------- GW to EM conversion \ EM Receiver --.....i----------1~ Conversion EM Source Noise Noise Noise Noise Figure 16. Conceptual SNR Fill Factors: Signal and Noise Components In the receiver all these same noise sources are duplicated in reverse, as shown on the right had side of Figure 16. Referring power now to the input, there will be a received power, and the created by the receiver that was not created at the transmitter, also GW to EM conversion noise, and EM receiver noise of the same types as received propagated transm it noise. Added to this will be GW noise admitted or outlined for transmitters. When all these noise components are referred the input of the receiver, the total NEP, wh ich is the RSS of all the noise components, must be less than the signal present at the input of the receiver to qualify as a useful link. A few comments are in order regarding the "Q-factor" of the receiver. One way to increase Q is to narrow bandwidth . However, this has lim ited va lue. At some point, shrinking the bandwidth will shrink the signal received as quickly as the noise received, and some receiver noise components remain constant, resulting in a net drop in SNR. Another way to increase Q is to arbitrary increase sample times of the signal. This technique will, relatively speaking, shrink receiver end noise components as referred to the input of the receiver, but it will not have any impact of the noise generated at the transmitter. Therefore in this case the SNR will approach a constant. However, both of these approaches for improving sensitivity will have an adverse effect on the information capacity of the channel, which is important for a communication application . 3.1.2 Link Budget Considerations Now consider the signal side of the commun ication cha llenge. The central question is, How do we close the link? That is, how much signal is necessary at the input of a commun ication channel to have a usefu l signal at the other end? These questions may be answered, qualitatively in this case, by considering the terms of the expression in UNCLASSIFIED/ /FOP OiiiilCl.t.k l!ISI!!! l>flti 23
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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.