"The drivers behind the D-series were two-fold: firstly, there's continuity of service. One of the primary things the D-series satellites will do is replace the existing B-series satellites, with the first of those, B1, due to reach its end of life at the end of 2006," says Dr Mark Harwood, Planning and Strategy Manager for Optus' Satellite business.

"The other driver was to look at providing growth, because we find here, in the Australian and New Zealand markets, that satellite communications has a very bright future, that there's lots of opportunities. We're seeing growth, particularly in the direct-to-home services market".

The B1 satellite, successor to the Optus A-series (Australia's first national communications satellite system), was launched in August 1992, on a Chinese Long March 2E booster from Xichang, China, and is Optus' hot bird for New Zealand, primarily carrying pay TV and communications services.

The B3 satellite was launched in August 1994 and was designed to enhance existing satellite communications services throughout Australia, including direct TV broadcast to homes and remote communities, voice communications to urban and rural areas, digital data transmission, high-quality television relays between major cities, and centralized air traffic control services. B3 was replaced as Australia's hot bird by C1 in 2003.

The two B series satellites also use high-powered spot beams covering major cities to provide specialized services, such as high-performance data links, videoconferencing, and a range of other dedicated services.

The major differences, says Harwood, between the D and B series satellites lie, firstly, in technical performance, but principally in the D series' ability to provide in orbit back up for mission critical services and applications, like pay TV.

"If you think of our Sky New Zealand customer, for instance, who deliver the bulk of their pay TV services via satellite...if something were to happen to the B1 satellite, this would lead to a significant service interruption. They were very keen, then, to see some method of providing backup for their services in orbit.

"It's actually a worldwide trend, says Harwood: "people are looking more and more to lower risk strategies for delivering their business objectives. All the direct-to-home service providers in Australia -are interested in knowing what the back up process is.

"So the way we designed the D-series was to go down the path of choosing two small satellites rather than buying one large one. And that gave us the ability to put additional capacity at our hot bird location for Australia, at 156 - that's where the C1 satellite now is- on the D2 satellite, which will be co-located with C1.

"D2 will have a broadcast services payload, so it operates at a different frequency band, but one which is directly contiguous with the existing C1 frequency band.

"The value of this is that the consumers' dish just needs to have a wide band receiver, and it can actually receive signals from either D2 or C1... and its just the same installation; installing a wideband front end costs virtually nothing additional.

"So the D series satellites give us the ability to add payload to the 156 orbit location, which is the Australian hot bird location, and at the same time replace B1, which is at 160, and that's where all the New Zealand dishes are pointing. So this gives us continuity of service for Sky New Zealand at 160, as well as growth capacity for the Australian market at 156.

"We added as well on D2 a New Zealand back up capability, so in the event that something happened to D1, the Sky New Zealand services could be restored immediately on D2.

"And what they're doing throughout New Zealand is install dual beam dishes so the consumer's installation actually looks at both 160 and 156 simultaneously, so they could restore services in the unlikely event of the loss of the spacecraft (historically an extremely rare event.)

C1's commercial payload (as opposed to its defence payload, which is not discussed in this article) is predominantly used for direct-to-home TV broadcasting (with Foxtel being Optus' largest customer), as well as for providing remote area broadcasting services (RABS) of local ABC, SBS and commercial TV content.

C1 was also designed to be able to carry multi-carrier traffic for data and voice applications, says Harwood, as well as having a steerable beam to provide additional coverage over South East Asia and North Asia.

The D series, on the other hand, will cover Australia and New Zealand, being very much designed for these local domestic markets.

"When D2 is co-located with C1, we expect to see growth in the direct-to-home market so it may be that we do get VSAT traffic ultimately onto C1, but it will most likely always carry a significant number of direct-to-home broadcast services".

"With the D2 launch, it'll be the first time in Australia that the broadcast satellite band (spectrum) will have been opened up. This is a fairly significant step in terms of the usage of spectrum" notes Harwood.

"The current B series platform will likely continue the Mobilesat (L band) service through until at least 2014. What happens then is subject of some current planning activity we're now engaged in with respect to where we'll take that particular product", Harwood continues.

D Series Technology Advancements

"Part of what we do is constantly monitor developments in spacecraft technology so we know what can be done, what's achievable, and then match that against where we think our business is heading, or what the most likely growth path will be, and then come up with a performance specification for a spacecraft which pushes the boundaries of the technology, but not to a point of taking excessive risk", Harwood says.

"There are a lot of developments happening now in spacecraft, with onboard processing technology - we've just seen the successful launch of the IPSTAR satellite, which has an exceptionally complex payload on it; it's the largest commercial spacecraft ever launched; it just completed in orbit testing; it's an extremely expensive spacecraft. It's a very high-risk strategy for the Thais, but will we do something like that? I don't know, Harwood muses.

Optus is a fully owned subsidiary of SingTel and a decision to proceed with any major infrastructure investment (i.e. the D-series), like buying new spacecraft, requires the appropriate internal approvals.

"I guess our approach typically (with respect to constructing sophisticated spacecraft) has been to try to put as much intelligence on the ground, and keep the satellite fairly simple- in the sense that they're really just bent pipes- but making use of developments in technology; antenna design, travelling wave tube amplifiers, propulsion and attitude control systems technology being good examples... ", Harwood says.

"If you compare the D series satellites to C1, which was launched only two and half years ago, the D series will be much smaller spacecraft but will provide higher performance on the ground for direct-to-home broadcasting services, and part of the reason for that is because they are small the distance from the amplifier output to the antenna feed is less, so there's less loss.

"For the D series, we're using similar technology for shaping the antenna beams, but the efficiencies of the TWTA's are exceptional; they're now pushing the upper 60%'s. When the (Optus) A series satellites were launched, we were struggling to get in the 30-40% range... so you can see there have been massive leaps."

D1 & D2 Launch Arrangements

Optus went through the usual competitive tender process to select the launch vehicle service provider for D1 and D2, "and Arianespace were the best-value-for-money offer," says Harwood.

"The contract we have for the launch is actually rather novel in that we wanted to have back up for both launches, for D1 and D2- the ability to revert to an alternate launch vehicle in the event there was a delay with the primary vehicle, for some reason.

"We've entered into a contract with Arianespace for the launch of D1, but with a back up using Sea Launch, in the event that the Ariane rocket is unable to launch D1, in time to replace B1.

"We also have a similar arrangement in place with Arianespace for the D2 launch. Ariane has been working with the Russians to integrate the Soyuz launch vehicle into French Guiana. The program that Arianespace has in place with Soyuz is to construct a new launch pad in Kourou, a few kilometres north from where they currently launch the Ariane rockets, however its unlikely that that is going to be available to us by the end of 2007, which is when we need to have D2 launched. So at the moment, it's highly likely that we'll launch D2 on an Ariane rocket.

Market Opportunities - New And Old

"We see remote areas as being a major market for satellite services", says Harwood. "With the government's subsidized HiBUS (High Bandwith Incentive Scheme) scheme put in place last year, we've seen a very significant take up of VSATs".

The Australian government has given about $150 million worth of subsidies so far to people, companies and organizations that have demonstrated that they live a certain distance beyond the nearest telephone exchange to cover the costs of installing broadband infrastructure.

"This scheme is really helping to take away the entry barriers for the guy in the bush to using satellite services. HiBUS is ramping up our presence in the bush."

"All the infrastructure in the remote areas of Australia is fundamentally provided by the incumbent, and until recently, with a strong emphasis on terrestrial services only.

"Optus contributes a significant amount each year to the Universal Service Obligation, which continues to feed the old infrastructure again; we're saying to the government that we should be able to use those USO funds to invest in competitive infrastructure for the bush, which will then lead to competitive service provision, and improved quality".

One very demonstrable improvement Optus pioneered was its Interactive Distant Learning (IDL) platform that made obsolete the old two-way HF radio technology used the School of the Air between teachers and students in remote locations.

Thanks to Optus' investment, school students around Australia can now see their teachers on a monitor, participate remotely in real-time lessons, uplink their own material, see graphics sent back from their teacher, and have dialogue with other students elsewhere. As terminal equipment costs have come right down, and capability and flexibility has become vastly greater, these services have become affordable.

Optus also introduced the world's first domestic land mobile satellite service, called MobileSat, that was launched with the B series satellites in 1994. Consisting of an in-vehicle mounted voice based system that also relays low speed data, it is sold to a number of markets, including the transport, railways, and fisheries markets, the Royal Flying Doctors Service, and pasturalists and miners working in remote areas of Australia. More recently, Optus introduced a new enhancement to the MobileSat platform called Closed User Group, that has great application for emergency services.

Through fibre cables Optus has today interlinked its ground segments with SingTel in Singapore, giving it access to approximately 38 satellites in the Asian region, ensuring its strong, long-term regional leadership role in the global Satellite Age.

Related Links
Optus Satellite Professional Services
SingTel Satellite Systems
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