Value chain · CLM-1000
In plain terms
By 1981 the government's own compatibility study said the satellite's frequency band had not actually been allocated to it, listed which services each harmonic would land on, and concluded that radio telescopes could not work within about 150 km of a receiving site.
The claim as recorded
The programme's 1981 EMC assessment states that the 2.40 to 2.50 GHz ISM band was an assumption of the analysis and "has not yet been allocated for space-to-earth power transmission"; that the second harmonic at 4.9 GHz "is very near a radio astronomy allocation", the third at 7.35 GHz falls into a government satellite downlink band and the fifth at 12.25 GHz is adjacent to a band considered for TV broadcasting; that an SPS frequency assignment must sit at least 10 MHz from the ISM band edge; that noise sidebands at Arndt and Leopold's 1978 levels "would exceed interference limits only for the adjacent satellite broadcast band"; and, as its headline conclusion, that radio astronomy facilities "probably could not operate within a distance of 150 km from a rectenna site".
Evidence behind this: T3-programme assessment, the EMC summary report of the whole CDEP.
Scope and limits
A 1981 ASSESSMENT OF 1978 ALLOCATIONS AND A 1978 NOISE MODEL; the allocation position has changed many times since and the register's current-allocation records are CLM-0120 and CLM-0552 (CLM-0919 is the 1978 reading of the rules). The 150 km is the document's own estimate and is not derived on the page quoted.
What it assumes
The Reference System of DOE/ER-0023: 60 satellites, klystrons, 2450 MHz.
Where it comes from
PDF p.9, normalised: "The current EMC analysis is dependent on the assumption that the MPTS would operate in the 2.40- to 2.50-GHz industrial, scientific and medical (ISM) frequency band. Although this is a logical choice of frequency, it is not the only possibility and has not yet been allocated for space-to-earth power transmission." PDF p.14, raw: "The second harmonic of 2.45 GHz at 4.9 GHz is very near a radio astronomy allocation. In practice radio astronomy operates below the allocated band and would be impacted by SPS second harmonic radiation unless it was held to very low levels. The third harmonic at 7.35 GHz falls into a satellite downlink band allocated to government use in the United States... The SPS fifth harmonic at 12.25 GHz is adjacent to a satellite downlink band being considered for TV broadcasting"; "the minimum SPS frequency separation from the ISM band edge must be 10 MHz"; normalised: "Noise sidebands from SPS, if held to the levels computed by Arndt and Leopold (1978), would exceed interference limits only for the adjacent satellite broadcast band". PDF p.76, raw: "In the Reference System, all 60 satellites transmit at 2450 MHz... it is not possible to phase lock the satellites in such a way that the off-axis radiation from different satellites will remain phase-constant for all ground-based observers". PDF p.86, normalised: "Radio astronomy receivers represent the most complex area for interference mitigation because of the sensitivity and wide spectrum of observations. These facilities probably could not operate within a distance of 150 km from a rectenna site."
Basis: GHz of harmonic against allocated bands; MHz of separation from the ISM band edge; km of separation from a rectenna
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-1000
CLM-1000, Energy Aperture, as of 1981-01.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-543
- CLM-1001Besides the deliberate beam and the tubes' noise, the satellite's fifty square kilometres of warm solar array glow faintly at radio...CLM-1002The 1981 study tells you exactly which international rulebooks it measured the satellite against, report by report, and warns that the...CLM-1204A 1981 US government study worked out what happens when an airliner flies through the beam. Its wings would reflect some of the beam...CLM-1205A 1981 US study worked out what a satellite in low orbit feels when it flies through the beam. For a craft like LANDSAT, the strongest part...