Space systems & satellite networks | ACMA

Space systems & satellite networks

The Australian Communications and Media Authority (the ACMA) has a number of powers in relation to space objects such as satellites or launch vehicles. The ACMA focuses on the radiocommunications devices associated with the satellite network allowing it to receive and transmit signals.

These powers and other regulations are outlined in the Radiocommunications Act 1992 (the Act):

This section...

provides the ACMA with the power to determine:

Section 5

which space objects are Australian space objects . These are launch vehicles that commence their flight in Australia and satellite networks that we file with the International Telecommunication Union (ITU).

Section 10A

that a particular object is not a space object for the purposes of this Act.

Paragraph 16(1)(ca) and Section 23

the circumstances in which foreign space objects are subject to the Act. Currently, the only circumstance identified is the use of the spectrum to provide services to places in Australia (that is, use of Australian spectrum).

What is a space system?

A space system consists of one or more earth stations and a space station, which can transmit and receive information to and from earth stations or other space stations using radiocommunications.

A space station is a transmitting or receiving device located on a space object. A space station may be located on a launch vehicle or a satellite, or a transponder on a satellite.

An earth station is a transmitting or receiving device located on the ground. It may be fixed or mobile.

A satellite is a type of spacecraft, moving through space in circular or elliptical orbits around the Earth.

The two most common orbits are:

  1. geosynchronous (GSO or geostationary)

  2. non-geosynchronous (NGSO). Types of NGSO orbits may be Low Earth Orbit (LEO), Medium Earth Orbit (MEO) or Highly Elliptical Orbit (HEO).

Types of satellite networks

A satellite network may involve:

  1. more than one spacecraft (LEO satellite constellations for example)

  2. one spacecraft hosting two or more satellite networks

  3. using the entire capacity of a satellite, lease of one or more transponders, or lease of specific frequencies within a transponder.

The term ‘space systems’ applies to satellite networks. The ITU categorises some of the major categories of satellite services as follows:

  1. Fixed-Satellite Service (FSS)

  2. Broadcasting-Satellite Service (BSS)

  3. Mobile Satellite-Service (MSS)

  4. Earth Exploration-Satellite Service (EESS)

  5. Radiodetermination-Satellite Service (RDSS).

These are broad categories that can encompass satellite communication services for:

  1. land

  2. maritime

  3. aeronautical craft or vehicles

  4. amateur satellite activities

  5. emergency beacon satellite monitoring

  6. Global Positioning Systems (GPS)

  7. direct-to-home (DTH) sound and television

  8. data acquisition (weather systems and survey purposes).

One satellite can be made up of a number of satellite networks providing a combination of services, such as FSS, BSS, or MSS, in a number of different frequency ranges.

The frequency bandwidths employed can vary, from 75 kHz for use in telecommand and telemetry, to around 65 MHz for use in high capacity communication circuits.

Structure of satellite networks

Up and down links

In a satellite network, transmissions from Earth to space are known as uplinks. Transmissions from space to Earth are known as downlinks. Generally, different carrier frequencies are used for uplinks and for downlinks.

Feeder and service links

Two other distinct classes of links exist in most satellite networks:

  1. feeder links the transmission path for channels between gateway earth stations and satellites that carry trunk or network traffic

  2. service links the transmission path for channels between end-users and satellites that carry traffic intended for end-users such as DTH radio, television and internet services or satellite mobile telephony.

BSS - the uplink is typically a feeder link that transmits broadcast radio or television content to a satellite for retransmission to end-users such as pay TV subscribers.

FSS - feeder uplinks and downlinks were originally between small numbers of gateway earth stations, but more recently, services are provided directly to end-users through service uplinks and service downlinks.

MSS - provides services directly to end-users and used both feeder and service links, with feeder links connecting satellites to gateway earth stations that interface with the broader telecommunications network.

Satellite transponders

The satellite can be viewed as a 'repeater in the sky' receiving information from one location and relaying it to one or more locations. The device located on the satellite that performs this function is known as a transponder. A satellite may have many transponders, each operating on different frequencies and providing different services.

Bringing a satellite network into use does not always involve launching a new satellite space station and placing it in orbit. Sometimes a new network may be established simply by using part of the transponder capacity on an existing satellite. One satellite may act as the space station for several satellite networks with entirely different names and operated by or for entirely different users.

Spectrum available for satellite services

The International Telecommunication Union (ITU) Table of Frequency Allocations is set out in the Radio Regulations.

Australian allocations are set out in the Australian Radiofrequency Spectrum Plan (the Spectrum Plan).

Satellite service plans

To ensure satellite networks do not interfere with existing and planned satellite networks and terrestrial services, the ITU Radio Regulations require a satellite network to be coordinated with all administrations that may be affected.

The ITU has already established arrangements to allow for the use of certain frequency ranges by Member States. These pre-planned arrangements include:

  1. The Broadcasting Satellite Service Plan set out in Appendices 30 and 30A of the ITU Radio Regulations (the BSS Plan)

  2. The Fixed Satellite Service Allotment Plan set out in Appendix 30B of the ITU Radio Regulations (the FSS Plan).

Operating satellite networks in accordance with either of these plans does not require detailed coordination with other countries. However, establishing a satellite network in unplanned satellite bands or establishing an additional satellite network in the planned bands does require this. Most satellite systems have been established in unplanned bands.

Satellite licensing

Getting the right licence to operate or communicate with a satellite service depends on how it will be used within a space network. Up and down links to and from the satellite may be licensed via the ground segment or space segment of the network.

Space Licence - Issued to a satellite operator or service provider specifically to authorise transmissions.

Space Receive Licence - Issued specifically to authorise reception of transmissions.

Radiocommunications (Communication with Space Object) Class Licence 1998 (the Class Licence) - When space stations are licensed via the space segment, the operation of ubiquitous earth stations that are communicating with them may be authorised by a class licence issued by the ACMA.

The ACMA will consider the appropriateness of space segment licensing for specific bands, other than those mentioned in the Class Licence, on a case-by-case basis.

When licensing transponders on satellites to provide services in Australia, the satellite itself must be made subject to the Radiocommunications Act 1992.

Before a Space or Space Receive licence can be issued it must be determined if it is an Australian space object or a foreign space object.

Last updated: 16 April 2019