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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.
“Harder”1 page
UNCLASSIFIED//F9A: 9FFHil.tzL 1!181!! 8HL'f 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 only be one case to check, so result is Tacq = 1 x 1 x 1 x 5 μsec = 5 ~tsec acquisition time. This is essentially instantaneous for applications such as TCP/IP or VoIP. This will favorably impact the overall TOMA 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 SO 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 terminals, allowing for finer phase encoding. Phase noise limits the type of modulation and manner of encoding that can be performed in phase space, commonly used for over the air telecommunication systems. An HFGW FTS system could reduce phase noise by providing a frequency reference with outstanding stability. For example, moving from QPSK to SPSK or 16-PSK improves 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 only 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 SPSK, 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). 29 UNCLASSIFIED// I OK orr1e1111t ~:!I! 8HLV
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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.