This time I’m not being so optimistic. Boy, this is taking a long time.
Four years ago, I wrote about the new broadcast satellite band at 17/24 GHz and how slow the FCC was moving in adopting rules to allow its use. Well, another shoe has dropped, as the FCC has at long last adopted some (but not all) additional rules to deal with interference issues. But there are more shoes yet to come. Boy, this is taking a long time.
To review, in 1992, the International Telecommunications Union adopted an allocation for broadcasting-satellite service (BSS), with 17.3-17.8 GHz as the downlink broadcasting band and 24.75-25.25 GHz as the uplink – or feeder link – band. The existing DirecTV and Dish BSS systems use 11.7-12.2 GHz as the downlink band and 17.3-17.7 GHz as the feeder link band. The FCC calls the DirecTV and Dish satellites direct broadcast satellites (DBS) to distinguish from the 17/24 GHz satellites.
The complicated wrinkle here is that the 17 GHz band is going to be used both for uplink (Earth-to-space) with DBS and downlink (space-to-Earth) transmissions for 17/24 GHz satellites. That creates some unique interference scenarios, unique in the sense that the FCC has no experience with such a configuration.
In 2007, the FCC adopted a number of policies for the new band, but the interference issues were far from resolved. Among the 2007 decisions was four-degree orbital spacing for the satellites (compared with nine degrees for the existing DBS service). That should support service to half-meter dish receivers, about the same as DBS antennas. The orbital spacing is tied to the antenna size – as frequency increases, dish antennas of a given size become more directional (their beam-width becomes narrower). The concern is that a receiver pointed at one satellite will receive some energy (interference) from the adjacent satellite. So in 2007, the FCC decided that the combination of four-degree spacing and half-meter dishes was practical and would avoid adjacent satellite interference.
And also in 2007, the FCC released a Further Notice of Proposed Rulemaking to deal with the other interference issues. I said in my 2007 column: “Based on past performance, we’ll get an answer from the FCC in about a year.” Boy, was I off.
There are two other kinds of interference now being considered: “space path interference” and “ground path interference.” The space path interference occurs when the downlink signal for a 17/24 GHz satellite enters the receiver located on a nearby DBS satellite, which wants to receive a 17 GHz uplink signal. It’s possible for a 17/24 GHz satellite to be located close to a DBS satellite, and the closer they are, the more chance of interference.
The ground path interference occurs when a 17/24 GHz subscriber receiver is located near a DBS GHz feeder link earth station. As I said in 2007: “The tougher question is the deployment of new 17 GHz feeder link stations. As new satellites are designed with more spot beam capability, and as EchoStar and DirecTV try to carry local broadcast signals from additional cities, it seems likely they will want to build more feeder link earth stations. What happens if they want to build a new station say 10 years from now, in an area where there are some 17 GHz DBS home receivers?”
This latest FCC order deals only with space path interference. It contains page after page of mind-numbing discussions of off-axis power flux density, antenna offaxis gain, and limits on orbital inclination and eccentricity. It contains a requirement that DBS satellites and 17/24 GHz satellites be separated by at least 0.2 degrees. Buried in a footnote is the statement that a separate order will deal with ground path interference.
Back in 2007, it appeared that the only companies interested in the 17/24 GHz licenses were EchoStar, DirecTV, Intelsat and Pegasus. Is anyone losing patience? Well it seems that in 2009, Intelsat and Pegasus surrendered licenses for 17/24 GHz satellites, and earlier this year, EchoStar surrendered its 17/24 GHz licenses. But DirecTV still retains its authorizations and launched hybrid satellite DirecTV 12 in 2010 – now located at 103 degrees West – with a 17/24 GHz payload, in addition to DBS capability. More recently, SES Americom filed for authorization to launch a hybrid satellite with C-band, Kuband and 17/24 GHz capability, intended to operate at 87 degrees West.
But neither DirecTV nor SES can start providing service until all of the technical rules are finalized, including the not-yetissued rules for ground path interference. And then there are numerous hoops to jump through before any commercial service can start – regulatory hoops, contractual hoops, marketing hoops, etc.
So this time I’m not being so optimistic about when 17/24 GHz will become a real satellite broadcasting service. The ITU started the process in 1992. I’m guessing that service will start around 2017, a mere 25 years later. Not something to be proud of.