ECSS-E-ST-50-05C – Radio frequency and modulation (31 July 2008)

This Standard has been cancelled and replaced by ECSS-E-ST-50-05C Rev.1 (6 March 2009).


This Standard defines the radio communication techniques used for the transfer of information between spacecraft and Earth stations in both directions, and for the tracking systems used for orbit determination. It includes the following:

  • frequency allocation, assignment and use;
  • requirements on transmitted signals concerning, for example, spectral occupation, RF power levels, protection of other radio services;
  • definition of the permissible modulation methods and parameters;
  • specification of the major technical requirements relevant for the interface between spacecraft and Earth stations;
  • operational aspects, such as acquisition;
  • cross-support.

This Standard is applicable to all spacecraft supported by Earth stations[1] and to all controlled Earth stations operating in the Space Operation, Space Research and Earth Exploration-Satellite services as defined in the ITU Radio Regulations.[2]

Other space telecommunication services are not covered in this issue.

All requirements in this Standard are equally applicable to both the customer and the supplier with exception of clauses 4.3.1 and 4.3.2 which are applicable to the customer only.

Further provisions and guidance on the application of this Standard can be found, respectively, in ECSS-E-ST-50 “Communications”, and in the handbook ECSS-E-HB-50A “Communications guidelines”.

ECSS-E-ST-50 defines the principle characteristics of communication protocols and related services for all communication layers relevant for space communication (physical- to application-layer), and their basic relationship to each other. The handbook ECSS-E-HB-50 provides information on specific implementation characteristics of these protocols in order to support the choice of a certain communications profile for the specific requirements of a space mission. Users of the present standard are invited to consult these documents before taking decisions on the implementation of the present one.

This Standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00.

1 This Standard is not applicable to spacecraft supported by data relay satellites.
2 Under the term Earth Exploration‐Satellite service, the Meteorological Satellite service is also included.


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This standard cancels and replaces ECSS-E-50-05A (24 January 2003).