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CCSDS RF communications physical layer

by Yee Wei Law - Friday, 8 March 2024, 3:20 PM
 

The International Telecommunication Union (ITU) has defined a series of regulations or recommendations for space research, space operations and Earth exploration-satellite services [ITU20, Recommendation ITU-R SA.1154-0], but CCSDS has tweaked these recommendations for their purposes [CCS21, Sec. 1.5].

CCSDS has defined two mission categories [CCS21, Sec. 1.5]:

  • Category A for missions having an altitude above the Earth of < 2 million km.
  • Category B for missions having an altitude above the Earth of ≥ 2 million km.

Orthogonal to the preceding classification, CCSDS has also divided their recommendations into these six categories [CCS21, Sec. 2]:

  1. earth-to-space RF
  2. telecommand
  3. space-to-earth RF

  4. telemetry

    Here, “telemetry” encompasses spacecraft housekeeping data and mission data (e.g., video) transmitted from the spacecraft directly to an Earth station or via another spacecraft (space-to-space return link).
  5. radio metric
  6. spacecraft

For example, the recommendations for telemetry RF comm are summarised in Table 1.

Table 1: Telemetry recommendation summary [CCS13a, p. 2.0-5], where NRZ = non-return-to-zero, PCM = pulse code modulation, QPSK = quadrature phase-shift keying,  OQPSK = offset quadrature phase-shift keying, BPSK = binary phase-shift keying, GMSK = Gaussian minimum shift keying, APSK = amplitude and phase-shift keying.

Note:

  • For Category-A missions [CCS21, Sec. 2.4.12A], filtered OQPSK and GMSK modulations are recommended for high-rate telemetry in 1️⃣ the 2-GHz and 8-GHz Space Research bands, 2️⃣ the 8-GHz Earth Exploration-Satellite band, and 3️⃣ the 26-GHz Space Research band.

    Filtered 8PSK modulation is also recommended for the 8-GHz Earth Exploration-Satellite band.

    2 GHz, 8 GHz and 26 GHz are part of the L/S, X and Ka bands respectively.

    This knowledge base entry discusses usage of different frequency bands.

  • For Category-B missions [CCS21, Sec. 2.4.12B], GMSK is recommended for high-rate telemetry in the 2-GHz, 8-GHz and 32-GHz bands.

  • The 25.5–27.0 GHz band (part of K band) is already being used for high-rate transmission in many missions, and usage is expected to rise [CCS21, Sec. 2.4.23].

  • The 32-GHz band (part of Ka band) is planned to become the backbone for communications with high-rate Category-B missions [CCS21, Sec. 2.4.20B].

The Proximity-1 physical layer is separate from all the above.

References

[CCS13a] CCSDS, Proximity-1 Space Link Protocol—Physical Layer, Recommended Standard CCSDS 211.1-B-4, The Consultative Committee for Space Data Systems, December 2013. Available at https://public.ccsds.org/Pubs/211x1b4e1.pdf.
[CCS21] CCSDS, Radio Frequency and Modulation Systems—Part 1 Earth Stations and Spacecraft, Recommended Standard CCSDS 401.0-B-32, The Consultative Committee for Space Data Systems, October 2021. Available at https://public.ccsds.org/Pubs/401x0b32.pdf.
[ITU20] ITU, Radio regulations, 2020. Available at https://www.itu.int/hub/publication/r-reg-rr-2020/.
[McC09] D. McClure, Overview of satellite communications, slides, 2009. Available at https://olli.gmu.edu/docstore/800docs/0909-803-Satcom-course.pdf.