Advanced Television

Will OneWeb disrupt TV signals?

June 30, 2015

By Chris Forrester

Last week’s announcement that Channel Island’s-based OneWeb is planning to launch 648 small satellites into space, starting in late 2017, has created some concerns amongst established satellite operators.

The scheme calls for the satellites to operate in a polar orbit, transiting the Earth at 1200 kilometres (750 miles) above the ground and with very little latency between the satellites and the ground. That’s the good news. The more challenging news is that the craft are licensed to operate in the Ku-band, the exact same set of frequencies (12-18 GHz) used by the world’s DTH operators, and which orbit at much higher altitudes.

OneWeb’s design for the satellites calls for the use of ‘progressive pitch’ (which means they are slightly turned) in order to mitigate interference with the larger satellites which are in fixed geostationary orbit at almost 36,000 kms up (22,236 miles).

The ITU’s licences to OneWeb (initially granted in the 1990’s to SkyBridge, and then transferred to WorldVu, which OneWeb acquired) specifies that its power levels must also be adaptable so as not to interfere with their larger – and much longer established – cousins. These obligations, which OneWeb has agreed to, will in particular affect their transmissions in and around the equator. All DTH satellites orbit directly above the equator.

It is this particular obligation that has encouraged OneWeb to link with Intelsat, and will permit OneWeb clients moving onto an Intelsat Epic satellite should interference be a problem. Indeed, OneWeb founder Greg Wyler has said that he is happy to enter into similar agreements with other satellite operators.

There’s another challenge for OneWeb which is another ITU obligation that it ‘brings into use’ its allocated frequencies by June 27th 2019. OneWeb doesn’t necessarily have to start providing services by then, only to have its first batch of satellites in orbit and ‘occupying’ the frequencies.

Moreover, OneWeb’s filings are junior to those of the larger established players. In other words they have to demonstrate that their 650 satellites do not interfere with the larger spacecraft.

But there remain concerns, especially of potential interference as each and every one of these small satellites passes under the footprint of a DTH signal. OneWeb is obliged to lower the power level of any satellite under the beam of a DTH broadcaster, and hand over its signal to another one of its orbiting constellation.

Alternatevly, and perhaps the reason why Intelsat is included in the backers of the OneWeb plan, the constellation can ‘hand over’ its signals to Intelsat when it is in the equatorial regions. Intelsat’s CTO Thierry Guillemin, in his blog last week said: “OneWeb will be able to hand off traffic to Intelsat capacity over the equatorial zones – the region where GEO spectrum has priority, and a hurdle otherwise difficult for LEO constellations to overcome.”

In other words there are still significant challenges ahead for OneWeb, not least getting the first satellites into orbit and then proving to the long-established players that they do not create interference.

It was exactly these worries that caused SkyBridge to enter bankruptcy.

Categories: Articles, DTH/Satellite