Spectrum Management

related to Nobeyama and Chile
Masaaki Hiramatsu

NAOJ Spectrum Management OfficeNAOJ Spectrum Management Office Established in 2019 under
NAOJ Public Relations Center Masatoshi Ohishi
 Masaaki Hiramatsu Maki Ozaki Establish a healthycoexistence b/w radio
astronomy and other radio
application services.
 Maintain a beautiful starry
sky by reducing lightpollution.

 Radio application companies Administration（総務省）
 Delegates from other countries
 Satellite constellation operators2

Our Principle

Radio astronomers want to observe all frequency range.
Other radio users may want to emit at all frequency range.

All radio users, including astronomers, have to SHARE the frequency resource.

3Frequency Allocation in mm-wave band
White: Radio Astronomy as a PRIMARY service

H22

H40/Z45/EQ

ALMABand 1

T70/FOREST/7BEE
Band 2/3

Nobeyama 45m
Band 4Band 5

Band 6Band 74

Overall Structure of Spectrum Management
総務省
(MIC)

Radiocommunication
Sector, the International
Telecommunication
Union (ITU-R)

Subsecretaría deTelecomunicaciones(Subtel)
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Activities in ITU-R• Working Party 7D: Radio Astronomy• Discussion to produce reports and recommendation, tomake comments on documents from other WPs in orderto preserve radio quiet environment.

• New ITU-R Reports:

 RA.2508: Widely-distributed radio astronomy array systems operating
above 200 GHz

 RA.2509: Technical and operational characteristics of radio astronomy
systems operating below 350 MHz (85 cm)
 RA.2510: Technical and operational characteristics of radio astronomy
systems in the 67-116 GHz (3-4 mm) range

 RA.2512: Technical and operational characteristics of broadband,background-limited detectors operating in the millimetre-wave regime6Ongoing/New items
40 GHz Space Mobile
94 GHz Cloud Radar

76 GHz Car Radar
42 GHz “5G”
24 GHz (?) Wireless Power Transmission
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24 GHz (?) Wireless Power Transmission

24 GHz: adjacent to Radio astro. band (23.6-24.0GHz)
Background: 920 MHz/2.4 GHz/5.7 GHz WPT wasapproved in 2022 in Japan. → Some companies areinterested in ~24 GHz.
Current Status:

 ITU-R WP declines studies in 24 GHz in response to thecomments from radio astronomy and earth observation, but
technical development research is ongoing.

840 GHz Space Mobile42.5 GHz: adjacent to Radio astro. band (42.5-43.5GHz)

1.8 GHz

37.5-42.5 GHz

Background: AST SpaceMobile launched a test satellite
BlueWalker 3 (64m2 antenna)in 2022. Direct-to-Mobilecommunication is planned.
Current Status:

 Rakuten Mobile obtained test license in Japan.

Earth gateway
at Fukushima

 Doubts about legal legitimacy: direct-to-mobile comm. in
1.7 GHz is not assumed in Radio Regulation.
 Detailed arrangement in sharing conditions is needed.

942 GHz “5G” mobile phone39.5-43.5 GHz: adjacent to/included in Radio astro.
band (42.5-43.5 GHz)

Background: 37-43.5 GHz was identified for “5G” in 2019.
→ MIC considers to allocate 39.5-43.5 GHz to “5G” .
Current Status:

 ~40 km separation is needed to protect radio astronomy.

 Ongoing research in even higher frequency range (> 100 GHz)for “6G” !?

⇒ 240/300 GHz

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76 GHz automobile radar
76 GHz

76 -77 GHz: Co-primary with Radio Astronomy

EIRP: Equivalent Isotropic Radiated Power

Background: Maximum EIRP in the current regulation in
Japan is lower than in US/Europe.
→ Companies want to raise the limit.

Current Status: Discussion with radar companiesis ongoing.
 Calculated necessary separation
around Nobeyama and VERA.
→ a few – several x 10 km?

Radar experiment at NRO45m (May 2015)(Distance: 477m)

1194 GHz Cloud Radar

94-94.1 GHz: adjacent to Radio astro. band (79-94 and94.1-116 GHz)

Background: CloudSat reactivated in 2021 withunstable attitude control (several degrees uncertainty).
Current Status:

 CloudSat regularly publishes information on the expected
time it will pass over the radio astronomy stations.

 Coordination with the new satellite (ESA/JAXA EarthCARE,2024) has been made in 2022. Radar will be in silent state
above observatories (including ALMA and Nobeyama).
12Our Principle

Radio astronomers want to observe all frequency range.
Other radio users may want to emit at all frequency range.

All radio users, including astronomers, have to SHARE the frequency resource.

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