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Discussion in 'DIRECTV General Discussion' started by Sixto, Jun 17, 2010.
Yes. DIRECTV uses it for backhauling.
Ok, thanks Tom. Knew about the backhauls, but thought it was a separate license for the trip back on KA.
The portion of the article you quote speaks to FSS that is both very low power and below DBS band in frequency.
The references to dishes smaller than 9m and 5m suggests they're not talking about multi-focal offset "pizza dishes".
Since it dates back to 1983, I'd say it has everything to do with the spacing of the SATs and the uplinking to them, leaving the downlink "issues" to the providers to sort out, with the parabolic shape of the reflector.
I thought the discussion was whether or not any DBS provider could use 97W for additional Ka broadcast capacity as opposed to uplinks or backhauls.
I'd say enough posts here have shown the 2º spacing has proven to work, so 97W wouldn't be an issue, "other than" if our [not yours] current dish would need to be reshaped.
The higher frequency range of Ka, and the power levels of modern satellites, allow the smaller dishes we have on our roofs to work more like the 6 foot, multiple feed horn dishes used at earth stations for C-band. If you can make the LNBF only really see a 2 degree patch of sky, it doesn't really matter if there is another satellite 2 degrees away...the 97 LNBF won't see the 99 sats and viceversa.
I would say so as well, were it not for Tom's earlier statement about the Ka-band payloads at 101 actually being spot-beamed to eliminate potential interference with 99 and 103.
If true, then we really have no working examples today of two Ka-band CONUS beam birds with 2 degree separation. Not at all saying it won't work of course, but just pointing that it wouldn't be correct to say DIRECTV is already using 2 degree adjacent Ka-band slots in the way DIRECTV-97W and the satellites at 99W are intended for.
This is all assuming Tom is correct about the Ka-band back-hauls at 101 being spot-beamed of course.
What all of this really comes down to is the focus of both the ground uplink dish and the SAT receiving dish. Being the old fart that I am, I remember when the FCC ruling came out after testing and an engineer's discussion of this ruling and its "impact".
This really isn't much different that filtering of a tuner to keep out adjacent channels, but instead is the focusing of the dish signal, on the uplink path.
Think of all the CONUS & spot beams that our dishes "filter out" so they can receive the SAT that we want.
For those having a hard time with this, think of an adjustable flashlight that you can focus the beam with. The dish on the uplink works the same way.
2 degree spacing works on C band where the -3 db point on a standard 10' dish is much wider than a KU dish, and KA is even narrower (note the fine tuning adjusters needed for KA band?)
Turn your dish one degree, and see if you have any signal at all. Im sure the interference they are referring to, is interference from the ground station to neighbor satellites, not interference from the satellite to the ground stations.
With sufficiently large dishes at the uplink site, I have no worries they can avoid interference with a satellite 2 degrees away.
Think DirecTV has that covered:
C-band isn't scattered/diffused by atmosphere like the higher frequencies may be.
IIRC, the ITU believes that 3 degree spacing is necessary in the Ka band broadcast.
Again, this is SPECIFICALLY ADDRESSED on p. 12 and Appendix A of the recently-filed Directv 97W Narrative document referenced by Sixto a couple of days ago, harsh and P Smith's vaguely-worded FUD notwithstanding.
All that would do is attenuate the signal, its not going to "move it" from 97 to 99 on the way down.
How do you reconcile "work like" and Ka rain fade?
Does anyone use a 6' dish for C-band?
The question remains: can a Ka satellite at 97W deliver a CONUS signal to DIRECTV subscribers that will work with a OTARD qualifying dish?
Would DISH Network have been able to use the slot for similar purposes?
While there are many posts in this thread, few, if any have addressed this important question with definitive answers based on RF theory or practice. Because DIRECTV subscribers are back to singing the the virtues of quality over quantity again, this would seem to be an important distinction.
:nono: like you would even know any of these if they beat you over the head to get your attention. :nono:
"The only question" is really if our current reflectors will work for Ka from 97W, which may be the difference between the old AT-9 and the AU-9.
More important, the projected DTV Ka sat @97W is offtopic and who knows if would be build:
P. 17 of that initial doc.
Yes, I do. No issues with it at all, except low power from the satellite occasionally. I never have issues with other satellites next door. My actuator moves from one to the other, and the first disappears before the second appears.
No it is NOT off-topic. The topic is Directv satellite discussion. Parenthetically, it includes what we know about D14 because D14 was specifically mentioned in a recent investor presentation.
Just keep the sidetrack for new 97W sat - what could be user friendly name of it ? D-15 ?