Value chain · CLM-0952
In plain terms
A solar power satellite would have to stay below published interference limits, and the limits differ by who is being protected. Microwave relay links get a limit per 4 kHz of bandwidth. Radio astronomy and deep space research get limits stated per hertz, which cannot be ranked directly against the relay limits. The radio astronomy and deep space limits are recommendations rather than binding rules, and the report says what protection radio astronomy really has is not clear.
The claim as recorded
The protection criteria an SPS would have to meet are numeric, published, and four different kinds of thing. As stated by the 1977 assessment: line-of-sight microwave relay, from the International Radio Regulations, an upper limit between -154 and -144 dBW/m2 in any 4 kHz band near 2 GHz depending on angle of arrival, and -152 to -142 dBW/m2 in 4 kHz near 5 GHz; troposcatter links, an additional IRR restriction near 2 GHz limiting the interfering signal at the receiver terminals to no more than -168 dBW in any 4 kHz band, set that way "because of the difficulty in defining a generic antenna size"; radio astronomy, the CCIR recommendation at the isotropic level, -247 dBW/m2-Hz near 2 GHz and -241 dBW/m2-Hz near 5 GHz; deep space research, the CCIR recommendation, not to exceed -220 dBW/m2-Hz at ground receiver terminals for more than 5 minutes per day. The report notes that the IRR affords no specific protection to radio astronomy or deep space research, so those two rest on recommendations rather than regulations, and it says the protection actually afforded to radio astronomy "is not clear".
Evidence behind this: T3-primary-report, and the tier is doing real work: these are SECONDARY statements of criteria that live in CCIR recommendations and the International Radio Regulations, neither of which this register holds in any edition. The numbers are as good as the report's reading of instruments nobody here has opened.
Scope and limits
THESE ARE 1977 READINGS OF INSTRUMENTS THIS REGISTER DOES NOT HOLD IN ANY EDITION, and both the CCIR recommendations and the IRR have been revised since. No figure here may be cited as a current limit, and confidence is MEDIUM for that reason rather than because the reading is doubtful. THE REPORT ITSELF HEDGES THE RADIO ASTRONOMY FIGURE - "the exact protection afforded to Radio Astronomy is not clear" - and attributes it to what the US "has tended toward" rather than to a binding rule. THE UNITS ARE NOT COMPARABLE ACROSS THE FOUR without a bandwidth assumption: dBW/m2 in 4 kHz and dBW/m2-Hz are different quantities, and a reader lining them up as a severity ranking would be comparing a band-integrated limit with a spectral density. The antenna sizes used for the conversions are 1977 values.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
All figures read from SRC-450 PDF pp.33-34 on registration. The line-of-sight limits and the radio astronomy figures match at the normalised level; the text layer corrupts freely in this passage and the corruptions are shown rather than repaired - "Near 2 G1z" for 2 GHz, "4 KHz" for 4 kHz, "-241 dBW/m2.Hz near 5 0Hz" for 5 GHz, and the deep space sentence renders "the applicable CIR recommendation" for CCIR and -220 dBW/m2 followed by a stray quotation mark and Hz where dBW/m2-Hz is meant. The deep space sentence is therefore TRANSCRIBED, NOT QUOTED. The report also gives the conversions it used to turn per-hertz criteria into power spectral flux density: a 10 metre geometric mean for troposcatter antennas and 64 metres for the largest deep space antennas then in use. CORRECTED 2026-09-15 ON VERIFICATION: the claim said four kinds and listed three. Troposcatter was in the conversion arithmetic and missing from the enumeration; it is now the second of the four, verified at PDF p.33 at the normalised level.
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-0952
CLM-0952, Energy Aperture, as of 1977.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-450
- CLM-0949There is a standard international curve describing how quickly an antenna's stray radiation should fall away off-axis. The SPS pattern...CLM-0950A solar power satellite in geostationary orbit cannot make its beam any tighter than its design figure, because it is too far away to focus...CLM-0951The usual way to stop a strong transmitter interfering with other radio users is to smear its power across a wide band. For a solar power...CLM-0969If the tubes are only 70 per cent efficient, the transmitter's own face is not big enough to get rid of the heat they make, even spread...CLM-1408In the late 1970s, US studies sketched receiving stations raised on posts or legs so the ground beneath could still be farmed or built on...CLM-1413A 1977 NASA-funded report says the metal mesh behind a receiving station's antennas can be about three-quarters open to light while letting...