Value chain · CLM-1021
In plain terms
Boeing ran the timing reference down glass fibre in four stages, measured each fibre's delay by sending the signal back, and used a second tone at half the frequency to tell which cycle it was in - the same trick satellite navigation uses. Every one of the hundred thousand tubes got its own phase corrector.
The claim as recorded
Boeing's Phase II reference system distributes the reference phase as a four-level fibre-optic tree: three Level One receivers on named subarrays take the spread-spectrum pilot from the ground and demodulate it to a 980 MHz intermediate frequency; 20 Level Two and then 380 Level Three slave repeaters are fed over actively delay-compensated two-way fibre links that return the signal so the total delay is held to a multiple of 2 pi; and a 490 MHz half-frequency signal is added "to provide compensation for the cabling phase shift ambiguities that the 980 MHz line length compensation circuit alone does not provide". Total mass 84,481 kg, of which 83,200 kg is fibre (the sum of the three cable lines, not a printed figure); design reliabilities .99999, .9998 and .998 over thirty years; conjugation at the klystron level, 101,552 conjugators, chosen over subarray level for a tilt and curvature loss "very conservatively estimated at 1%".
Evidence behind this: T3-contractor reference system description, a design with a mass and reliabilities but no test.
Scope and limits
A 1979 DESIGN DESCRIPTION WITH A MASS AND A COST; NO TEST RESULT, AND THE DERIVATION IS ATTRIBUTED TO LINCOM WORK NOT HELD. The pilot's spread-spectrum parameters are not given here (CLM-0979).
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.117, normalised: "divided into 20 sectors"; raw: "spread spectrum reference phase signal from the pilot beam transmitter on the ground"; "980 MHz if frequency". PDF p.119, raw: "490 MHz", "ambiguities", ".99999", "84,481"; the sentences on holding total delay to a multiple of 2 pi and on the 490 MHz signal compensating "the cabling phase shift ambiguities that the 980 MHz line length compensation circuit alone does not provide" transcribed because the text layer joins them across hyphenated line breaks; the mass table from the render, fibre 83,200 kg of 84,481. Klystron-level conjugation and the 1 per cent are on PDF p.73 (printed 47), in the parent WBS 1.1.2 text, read at the render: "Phase conjugation at the individual klystron level was selected over control at the subarray level ... The improvement in efficiency is very conservatively estimated at 1%" (the text layer prints "estimated at 106"), the page continuing "Since there are 10^5 klystrons, each requiring one receiver"; the 101,552 is the klystron count on PDF p.97 ("7220 subarrays; 101,552 klystrons") and p.114. The symbol after "multiple of 2" is not reproduced by the scan; "2 pi" is a reading of it.
Basis: MHz; kg; reliability over 30 years
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-1021
CLM-1021, Energy Aperture, as of 1979.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-495
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