Value chain · CLM-1311
In plain terms
The 1979 design sends a sample of the reference back up each cable and adjusts until the far end matches the source. That makes cable length stop mattering. What still matters is any difference between the trip out and the trip back, and small fixed offsets in each box. These pile up from the centre to the antenna elements.
The claim as recorded
In the 1979 baseline the MSRTS reference distribution cancels cable path length but leaves, on each hop, a residual equal to half the difference between outbound and return delay times the angular frequency. These residuals add down the tree: the tip phase error is (1/2) sum dtau, with variance (1/4) sum sigma^2. The report models the hardware sources (multiplier, four-way splitter, PLL network and couplers, reflective termination, end coupler) as static, zero-mean random phase shifts with no magnitudes assigned.
Evidence behind this: Contractor analytical model in a NASA contractor report. Equations read at render. No hardware data.
Scope and limits
No numeric sigma for any component; thermal drift explicitly neglected. The III.8 sum is written in delay units without omega_s (source notation). The PLL noise propagation result (Fig. III.7, PDF 185) is normalised and was not read at render here (unverified).
What it assumes
Reciprocal, nondispersive cable; independent errors across hops; tree treated as one chain per tip (printed p.179, PDF 186).
Where it comes from
printed p.34 (PDF 42, render): the phase at point B "equals the phase at point A even if the effective cable delay varies". Printed p.162 (PDF 169, render): eq. III.4, theta_M + omega_s.dtau/2 with dtau = tau12 - tau21, and dtau = 0 only under "(This assumes a nondispersive cable)." Printed p.164-165 (PDF 171-172, render): independent zero-mean dtau, Var[y_n] = (1/4) sum sigma^2 (III.9). Printed p.75 (PDF 83, render): list of sources, "Each of these phase errors is a static error (neglecting thermal effects) and is set for all time." Printed p.166-168 (PDF 173-175): a bias c gives mean n.c/2; an alternating-direction circuit (Fig. III.3) reduces it to 0 or c/2 (paraphrase).
Basis: deg rms of reference phase at each tree node
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-1311
CLM-1311, Energy Aperture, as of 1979-03.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-647
- CLM-1312In 1979 the contractor simulated the whole reference-distribution tree. Small, random timing errors were added at each branching level, and...CLM-1313An error near the antenna elements is different at each element. It averages out in pointing but scatters power. An error near the centre...