Carrier ID for satellites for 2012 Olympics
Oct 3, 2011 2:37 PM, By Philip Hunter
The work of the Satellite Interference Reduction Group is more important than ever.
In June 2012, Eutelsat will become the first satellite operator to incorporate carrier ID in its transmission parameters for SNG (Satellite News Gathering) as well as for new DVB broadcasts. Coming in time for the 2012 Olympic Games in London, this follows strong lobbying from the Satellite Interference Reduction Group (sIRG), which hailed the move as a major breakthrough in the fight against interference.
As well as ensuring that Eutelsat’s own customers insert carrier ID into their transmissions, the move will help the sIRG in its campaign to persuade the other major operators, such as SES, Intelsat and Telesat Canada, to adopt the same carrier ID technology. The campaign will also be assisted by sIRG’s other IBC announcement that a number of leading modem manufacturers have agreed to cooperate in establishing a standard for insertion of new carrier ID technology within the DVB (Digital Video Broadcast) satellite transmission protocols.
The problem of interference has risen in proportion to the number of satellites in orbit (now around 2500 with numbers set to increase further). It is being driven by growth in DTH (Direct To Home) 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 is still increasing, exceeding 100 per month for large operators. Most of these are caused by badly installed ground terminals, uplink errors and poor equipment maintenance.
Incidents resulting from these and other causes vary in severity from slight signal degradation to total service outage, and the overall impact on operators is significant since it cuts effective transmission capacity, reduces uptime, generates costs to combat and potentially lose customers. Interference can be a short-term problem when caused by faulty equipment. Or, it can be long-term when occurring between nearby satellites operating in the same frequency bands.
Of course, Carrier ID does not solve the problem itself. But, it does enable sources of interference to be identified and contacted, which is often difficult at present. This is because use of TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access) or MCPC (Multiple Channel Per Carrier) techniques for transmission make it hard to pinpoint the remote earth station causing interference since several are using the same frequency range to communicate. The satellite operator can tell which customer is responsible, but the only way of drilling down to identify which station is causing the problem is to shut down each one in turn. This can take months and cause unnecessary downtime for end users.
Carrier ID allows sources to be identified by embedding the necessary information within the payload data. Specific data includes: customer name, contact telephone number, latitude, longitude, modem manufacturer name and modem serial number. This quickly identifies the source provided the carrier ID is readily accessible. To ensure this, the sIRG proposal is that it must be carried in the clear unencrypted, even when the payload itself is encrypted.
The carrier ID must also be carried in a standardized way, which is why the second sIRG announcement at IBC was important. It leads the way toward incorporation within the DVB-S standards. This step also addresses one of the concerns with earlier proposed implementations in which the carrier ID itself could be lost in the event of interference, which would completely defeat the objective. The proposal is to overlay the carrier ID across a spread spectrum channel, which would make it more robust against interference itself.
Following the progress made at IBC, the focus now for the sIRG lies in defining the process of managing carrier ID and ensuring that it is workable throughout the transmission chain.
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