Documents / Official release
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//iiOlil OiiiilCI0L Llili QPIL¥ 3.0 Operational Concerns 3.1 LINK BUDGET 3.1 . 1 Signal-to-Noise Ratio Signal-to-noise ratio (SNR) is an im portant figure of merit in communication systems because it is an indicator of whether or not a transmitted signal will be useful upon arrive at its destination, the receiver. Without processing gain an SNR > 1 will be required to maintain a link budget. On the transm itter's end, the signal to noise is determined by the useful signal that is produced by the transmitter after it is already in its transm ission mode, such as the GW power at the output of the GW generator antenna, divided by the RSS (Root Sum Square) of the uncorrelated noise sources referred to the same spot in the signal chain-that is, output referred noise equivalent power (NEP). This signal to noise ratio is represented by the left hand column in Figure 16. The components of the transmitter's noise equivalent power may be sorted by the source of the noise. First, before the signal is converted to GW it is in the rea lm of EM or photon radiation. Photons themselves make noise, and this component goes as the square root of the total number of photons. Then there is thermal noise-that is, the photons generated by blackbody radiation of the transmitter components themselves. Other electron ic and semiconductor components provid ing the source signal generate their own photon noise due to carrier activity. All these noise sources are carried along with the original EM signal and may be converted just as faithfully as if they were signals should they fall within the transmission bandwidth. All of this is just for the EM noise component. The generation process itself may also be a source of noise, and will vary widely depending upon the generator method used. For example, the generation process noise created in the GASER would be significantly different than that created in a tuned resonant EM toroid cavity. Th is of course would be an important consideration in selecting a generator type. Finally, it is expected that there are a variety of GW noise sources. Background sources from space are predicted, in low levels, across the entire frequency spectrum. Also, in a GW generator situation, pa rasitic vibrations may also have quadrupole moments, such as the walls of a generation cavity for instance, or an unwanted vibration within a slab of SC, and these could also generate GW noise. Then there is link loss to contend with. While it is expected that the attenuation of GW due to absorption and scatter will be quite low, geometry alone will dictate that a spherically uniform radiating source will fall off as 1/R2 . This link loss will affect both the transmitted signal and the transmitted noise. UNCLASSIFIED/ /FOR OiiiilCl.t.k HSI!! eflti 22
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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.