What is reverse band?

[manowell]

My installer at the house told me that the LNB needed to be switched out from a SWM to a RB SWM when I got a Genie and a 4K mini.

-- later --

I'm working on a tripod dish for an RV I'm picking up soon, and ordered new hardware for that from Solid Signal. Instead of the "DIRECTV Slimline Single Wire SWM Triple Satellite LNB (SL3-SWM)" that I ordered:

I received the 3D2RBLNB:

Didn't really notice this until I was playing with the aiming meter and the rig on the tripod last night, was frustrated with lower signal levels than I'm used to, and saw the AIM meter had detected (correctly, it seems) Reverse Band.

If I'm not doing 4K, do I care? Harder to align? This will be a dish aligned as we move, so easier to align the faster and better. Any power differences?

 

[texasbrit]

Nothing is using reverse band at the moment. It's believed to be reserved for future 4K programming. It makes no difference for alignment since it comes from one of the existing satellites.

 

[slice1900]

Other than the goofy name it got saddled with, you can think of it as a third Ka band similar to the existing 'Ka lo' (99cb/103cb) and 'Ka hi' (99ca/103ca)

Directv applied for the license for it a decade ago, thinking it would be used for 3D. Of course 3D never happened, so they decided to use it for 4K. Whether 4K happens remains to be seen, given that there are still no full time channels on the horizon. But if we ever start seeing a bunch of 4K channels, Directv is ready.

 

[manowell]

Got it. Got RB LNB aligned, there are four transponders on 99rb that show a signal......

 

[slice1900]

Got it. Got RB LNB aligned, there are four transponders on 99rb that show a signal......

I think that's still all they have active. They aren't broadcasting anything at all yet (other than maybe some internal testing with AT&T employees) since there are no 4K channels out there for them to carry, but Directv is ready and has been for a while now.

 

[goaliebob99]

Nothing is using reverse band at the moment. It's believed to be reserved for future 4K programming. It makes no difference for alignment since it comes from one of the existing satellites.

International programming may land up on Reverse Band as well. Sooner than you think.

 

[texasbrit]

As slice says, they are active but not broadcasting anything.

 

[slice1900]

International programming may land up on Reverse Band as well. Sooner than you think.

I doubt it. They'd need to upgrade EVERY international customer to a reverse band dish to make that happen, whereas if they put it on 99/103 Ka or 101 all the customers who have been installed in the past five years with a non-reverse band Slimline paired with their international dish would be fine. They will have tons of spare bandwidth once they drop MPEG2 SD, they don't need to make things harder for them in terms of required upgrades by putting internationals on reverse band.

 

[raoul5788]

How many international customers are there?

 

[slice1900]

How many international customers are there?

I really have no idea, and don't think Directv has ever shared that information. Anecdotally, people in the LA area have posted they see the international dishes all over.

Even if they only had to upgrade 100K customers, that's still millions of dollars they'd spend to be able to move the international channels to reverse band. Given that they will free up nearly 32 transponders on 101 when they drop MPEG2 SD (I say "nearly 32" because MPEG2 SD only channels on 101 will become MPEG4 SD only) so they will hardly need the room. Converted to MPEG4 SD, the channels on 95* would fit in three transponders so it isn't exactly gonna use a lot of bandwidth.

If they were going to convert them to reverse band, the time to do that would have been two years ago - mirror them not replace. Then all the installs they did for international customers in the meantime that installed two dishes and an external SWM could have installed a simple reverse band dish. That would have saved them millions I imagine, but maybe they weren't ready to begin broadcasts over reverse band back then.

I speculated at the time they'd do this, but obviously they didn't. Even then, I figured one they dropped the 95* satellite they'd probably move them back to Ka, to avoid the need to upgrade all the rest.

 

[nelson61]

Other than the goofy name it got saddled with, you can think of it as a third Ka band similar to the existing 'Ka lo' (99cb/103cb) and 'Ka hi' (99ca/103ca)

Directv applied for the license for it a decade ago, thinking it would be used for 3D. Of course 3D never happened, so they decided to use it for 4K. Whether 4K happens remains to be seen, given that there are still no full time channels on the horizon. But if we ever start seeing a bunch of 4K channels, Directv is ready.

You will not find "reverse band" in the FCC federal code defintions.

The FCC name is 17/24 GHz BSS.


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[Claude Greiner]

How many international customers are there?

Not very many.

But having the Italian Packages and Tv Japan is taking a significant number of customers from Dish.

I could see Directv moving Italian as they can’t keep up with the demand for international dishes.

If Directv could now get a decent Arabic and Hindu Package they could really hurt dish networks international base.

 

[Claude Greiner]

Bye, yeah the signal on the reverse band is about 10 points lower then a regular SWM.

But regardless both point the save

 

[slice1900]

Bye, yeah the signal on the reverse band is about 10 points lower then a regular SWM.

But regardless both point the save

There's no particular reason why it should have lower signal quality, Directv is authorized for the same power level as Ka and Ku. Either they are broadcasting reverse band at a lower power level for some reason, or there is something in the design of the reverse band LNB that causes it be received with a lower SNR.

That's perhaps possible because the "simple" way to do it would be to widen the 99/103 feedhorns to enable it to catch a lower frequency signal, split the received signal for each polarity, and use an image filter with the existing 18.05 GHz LO. That would output reverse band inverted from 350 - 750 MHz.

However, due to the proximity of the 99/103 feedhorns and the 101 feedhorn there probably wasn't room to widen them, so the reception ability at the lower frequency range of reverse band vs Ka may be slightly compromised. I would expect to see slightly higher readings (like a few points, nothing big) on transponders 17/18 vs 1/2 if that's the case. Maybe not on every LNB, but if we got a couple dozen and averaged them together that's the pattern you'd expect if this is the case.

 

[Claude Greiner]

A true test would be to have both dishes side by side with and without a reverse band and see how much a difference rain fade makes during a storm.

 

[slice1900]

A true test would be to have both dishes side by side with and without a reverse band and see how much a difference rain fade makes during a storm.

Why? You already have that information from the signal strength screen. The number on that screen is not signal "strength", it is a quality measure directly calculated from the SNR of the received signal. Rain fade reduces your SNR, and when it falls below the minimum signal margin for the modulation used (reflected with a reported "signal strength" of about 20 for CONUS Ka, or about 44 for Ku) it no longer has sufficient error correction information to be able to recover the signal, so it shows '0'.

If during clear weather the reverse band dish shows a '95' on a given transponder and a non-reverse band dish shows '97' on the same transponder, rain fade will affect the reverse band dish first. However, the difference between 95 and 97 is so small you'd be hard pressed to notice a difference even in a side by side test.

 

[nelson61]

There's no particular reason why it should have lower signal quality, Directv is authorized for the same power level as Ka and Ku. Either they are broadcasting reverse band at a lower power level for some reason, or there is something in the design of the reverse band LNB that causes it be received with a lower SNR.

The "reverse band" is downloading on the upload frequencies assigned to DBS 12.2-12.7.

The permits prohibit interference with the various upload sites used by DBS.

So, they have to manage (lower) the download power level at any conflicting DBS upload center (and there are lots of them).



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[slice1900]

The "reverse band" is downloading on the upload frequencies assigned to DBS 12.2-12.7.

The permits prohibit interference with the various upload sites used by DBS.

So, they have to manage (lower) the download power level at any conflicting DBS upload center (and there are lots of them).



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It isn't possible to lower the power at all Ku uplink sites, there are far too many, but this isn't a problem.

The uplinks broadcast at probably a billion times more power than Directv's reverse band is received on the ground, the interference isn't with the uplink sites it is the people who live near the uplink sites - if you are close enough (within a mile or so, especially if the dish is pointing in your direction) you will be unable to receive reverse band due to the spillover from the uplink.

 

[goaliebob99]

I doubt it. They'd need to upgrade EVERY international customer to a reverse band dish to make that happen, whereas if they put it on 99/103 Ka or 101 all the customers who have been installed in the past five years with a non-reverse band Slimline paired with their international dish would be fine. They will have tons of spare bandwidth once they drop MPEG2 SD, they don't need to make things harder for them in terms of required upgrades by putting internationals on reverse band.

They will do it because it’s cheaper to move all of those subs than keep leasing space at 95. New international subs will get Reverse band LNBs then old ones will move over within a fee years after that. Think about the cost factor and what would be cheaper and that’s where ATT will go.

 

[texasbrit]

Why? They can get rid of 95 and put all the international subs on99/103 or 101, there will be plenty of room after the MPEG2 channels go away.