The world’s broadcasters have taken a step forward in combatting the growing problem of satellite interference by agreeing in principle to require all uplinks to be identifiable via a newly agreed upon Carrier ID specification. Although this does not directly resolve the problem, universal deployment of carrier ID would make it much easier and quicker to identify sources of interference so that immediate remedial action can be taken.
Most uplink interference is accidental, caused by use of incorrect settings that jam signals. The problem has grown in proportion to the number of communication satellites in the sky, now approaching 3000,driven in turn by growth in DTH broadcasting, cellular backhaul and various point-to-multipoint data applications. Although the reliability of satellite transmissions has improved with reduced error rates overall, the number of interference incidents reported on a monthly basis has been almost continually increasing, exceeding 100 per month for large operators. The problem is amplified by the fact that satellites now aggregate broadcast channels in a ‘multiplex,’ so that interference affecting one service can also scramble numerous other channels. The issue is relevant for operators in all categories and not just DTH, because satellites deliver broadcast content to cable or IPTV headends and terrestrial transmitters as well as direct to homes. All of these depend on reliable uplinks from the field or studios to beam the signal up to the satellite.
The problem has long been recognized but the coordinated action needed has been slow to materialize. Europe took a lead with the Geneva-based DVB developing the Carrier ID standard, with strong support from the European Broadcasting Union (EBU). A significant landmark came in June 2012, when Paris-based Eutelsat became the first satellite platform operator to incorporate carrier ID in its transmission parameters for SNG (Satellite Newsgathering), as well as for new DVB broadcasts. Coming in time for the 2012 Olympic Games in London, this followed strong lobbying from the Satellite Interference Reduction Group (sIRG), which hailed the move as a major breakthrough in the fight against interference.
Although this was a unilateral move only requiring Eutelsat’s own customers to insert carrier ID into their transmissions, it put pressure on rivals such as SES, Intelsat and Telesat Canada to adopt the same carrier ID technology. This has culminated in the recent agreement by the European Telecommunications Standards Institute (ETSI) to adopt the specification, as well as endorsement by the WBU’s International Satellite Operations Group (WBU-ISOG).
Carrier ID includes the MAC (Media Access Control) address that uniquely identifies an uplink system, along with Carrier ID format version, which provides space for future extensions and improvements. Additional information that can optionally be transmitted and be configurable by the user includes Uplinker name and contact phone number to help in the subsequent process of dealing with the radio frequency interference (RFI ). Relevant supplementary information along with MAC addresses, names and contact details of respective uplink operators will be incorporated in a common database that will be accessible by all satellite operators and possibly other authorized bodies.
This will enable operators and users to quickly identify interfering carriers and respond to RFI, reducing the duration of each event, as well as operating costs. It will also improve quality of service, because the new specification will reduce the total number of RFI events and so release bandwidth that is currently being reserved to provide headroom against ongoing RFI events. This bandwidth provides resilience against interference to ensure continuity of service.
Although carrier ID will help address accidental interference, which is the main cause of uplink problems, it will do less to tackle the growing issue of deliberate and malicious satellite jamming by hostile countries. The Arab spring and the Syrian civil war have been associated with a surge in jamming incidents across the Middle East, which is a key area for satellite communications. Eutelsat reported 340 cases in the first 10 months of 2012, a threefold increase overall since 2009, with 90 percent of hostile signals traced to Iran and Syria.
Sources of jamming are unlikely to be directly identifiable via carrier ID, but its deployment could help by eliminating authorized uplink stations from investigations. At a meeting between broadcasters, satellite operators and equipment makers in Paris in January 2013, one option discussed was to enable satellite operators to share data about when and where malicious disruptions happen. This data would be stored in a common space for reference and used in discussions with international regulatory bodies. A start was made on creating such a database at the Paris meeting.
It is now possible to identify the geographical source of an interfering signal by using two satellites that are well positioned to locate it, in a process called ‘geolocalization’. With this information, the source of the interference can be found and logged, which should help implement counter jamming measures. A variety of techniques have been developed to counter jamming, depending on the situation, one being to concentrate a satellite’s power in a small frequency band and have the receiver filter out all other frequencies. If the jammer does not know what frequency the system using, it must spread its power over a much broader spectral range to make sure it covers the frequency that is actually being used, which is harder to achieve.
Such countermeasures can be deployed more effectively given a coherent global system for coordinating responses to all sources of interference.
