# What is Reverse DBS?



## ikoniq (Sep 8, 2012)

Can someone explain to me what Reverse DBS is, why it's so important, and what it means to me that DirecTV's new satellites have RDBS capability on them? As far as I know, all it encompasses is a new set of frequencies to downlink on, increasing the bandwidth. How does that affect current equipment? Will current equipment have to be changed out to utilize the Reverse DBS frequencies? Why is it called Reverse DBS? I have a lot of questions and an openly inquisitive mind, forgive me if it's all too much at once.


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## bakers12 (May 29, 2007)

Reverse DBS uses the normal downlink frequency band for uplink, and vice versa. That is, the download and upload bands are reversed. The idea is to get more bandwidth.

There is plenty of speculation about how DirecTV will use this and what it means to the average customer. We won't know for sure until DirecTV tells us. It's likely that the current dishes (at least) won't handle RDBS.


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## ikoniq (Sep 8, 2012)

bakers12 said:


> Reverse DBS uses the normal downlink frequency band for uplink, and vice versa. That is, the download and upload bands are reversed. The idea is to get more bandwidth.
> 
> There is plenty of speculation about how DirecTV will use this and what it means to the average customer. We won't know for sure until DirecTV tells us. It's likely that the current dishes (at least) won't handle RDBS.


So using Ka/Ku for uplinks...wouldn't that necessitate a huge reflector and impractically clear weather to accomplish, even at a commercial level?


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## slice1900 (Feb 14, 2013)

The KaKu (legacy) LNB almost certainly does not receive RDBS. If it does, a lot of MDU equipment would need replacement since frequencies above 2150 MHz would have to be used on the outputs. It is possible that the SWM LNB, which came out several years later than the KaKu LNB, was designed to receive RDBS, however.

If the SWM LNB can do so, it would have slightly larger feedhorn openings for 99 & 103 when compared to a KaKu LNB - you'd have to remove the plastic cover protecting them and measure each to tell. If anyone happens to have a dead/sacrificial LNB of each flavor laying around...


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## HoTat2 (Nov 16, 2005)

bakers12 said:


> Reverse DBS uses the normal downlink frequency band for uplink, and vice versa. That is, the download and upload bands are reversed. The idea is to get more bandwidth.
> 
> There is plenty of speculation about how DirecTV will use this and what it means to the average customer. We won't know for sure until DirecTV tells us. It's likely that the current dishes (at least) won't handle RDBS.


Not quite;

The downlink band for RDBS is "mostly" the same as the conventional DBS uplink band to within 100 MHz for service in the U.S., at 17.3-17.7 GHz.and fully at 17.3-17.8 GHz for other countries.

However the uplink band assigned is not the vice-versa, but up near the Ka band at 24.750-25.150 GHz for the U.S. and 24.750-25.250 GHz for other countries.


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## HoTat2 (Nov 16, 2005)

ikoniq said:


> Can someone explain to me what Reverse DBS is, why it's so important, and what it means to me that DirecTV's new satellites have RDBS capability on them? As far as I know, all it encompasses is a new set of frequencies to downlink on, increasing the bandwidth. How does that affect current equipment? Will current equipment have to be changed out to utilize the Reverse DBS frequencies? Why is it called Reverse DBS? I have a lot of questions and an openly inquisitive mind, forgive me if it's all too much at once.


Long story long;

Hope you enjoy reading, and technical talk mixed with legalese;

If so have fun ... 

View attachment 24117


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## ikoniq (Sep 8, 2012)

HoTat2 said:


> Long story long;
> 
> Hope you enjoy reading, and technical talk mixed with legalese;
> 
> ...


I didn't know PDFs exceeded 120 KB. Good job, FCC.


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## ikoniq (Sep 8, 2012)

Wait...what keeps RDBS from interfering with uplinks?


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## Diana C (Mar 30, 2007)

RDBS does downlink on the same frequency band that Ku uses for uplink (which is just below the current Ka downlink frequency). Since the downlink of RDBS is radiated out to the entire US, and the uplink of Ku comes from only a few discrete locations, and since the uplink uses highly focused antennas pointed at those locations, the potential for interference is fairly small. It is not zero, however, which is why DirecTV experimented with a small RDBS payload on the D-12 satellite. The experiments showed that there is no harmful interference.

However, I would not get too excited about this "additional bandwidth" just yet. I would think of it more as additional "potential" bandwidth. It highly unlikely that any existing LNBs can receive these frequencies (despite any speculation you may hear) since the capability is not on any LNB manufacturer's spec sheet. Therefore, wide spread use of RDBS for direct to home service is likely some considerable time off in the future. IMHO, it is most likely to be used for the delivery of 4k (aka SuperHD) content, since anyone subscribing to this service level would need new 4k capable receivers and, of course, 4k TV. These customers would very likely pay a premium for the 4k service. This is much preferable from DirecTV's perspective versus upgrading millions of existing customers just to deliver more HD.


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## HoTat2 (Nov 16, 2005)

ikoniq said:


> Wait...what keeps RDBS from interfering with uplinks?


Essentially spacing limits between DBS and RDBS satellites and stringent off-axis radiation standards for the RDBS transmitter antennas. How much of each is needed though is still a matter of controversy.

In fact there are actually two areas of concern for interference with RDBS;

A space path segment as I just described, where a RDBS downlink signal potentially interferes with a satellite's reception of a conventional 17.3-17.8 GHz DBS uplink signal.

And a ground path segment which is the potential for a DBS uplink site to cause interference to the RDBS 17.3-17.7 GHz reception of any nearby customers in the area of the uplink station.

At last report on file with the FCC of DIRECTV's experimentation with an RDBS test payload aboard D11 in June-July 2008, the test results for each segment were found to be rather inconclusive.

See here (if interested) for DIRECTV's detailed test procedure and results on the matter;

View attachment 24128


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## pjs344 (May 21, 2014)

From the info searches and what I have read on the Reverse band. It is basically adding new transponders by switching the up link to a down link band and adding a new 24 Ghz up link band. So you now have additional transponders and more bandwidth. DTV 15: 30 ku (12 Ghz), 24 ka (24 Ghz).18 reverse (17 Ghz) and up link (24 Ghz)


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## HoTat2 (Nov 16, 2005)

pjs344 said:


> From the info searches and what I have read on the Reverse band. It is basically adding new transponders by switching the up link to a down link band and adding a new 24 Ghz up link band. So you now have additional transponders and more bandwidth. DTV 15: 30 ku (12 Ghz), 24 ka (24 Ghz).18 reverse (17 Ghz) and up link (24 Ghz)


For the most part correct. ...

However D15 actually has 32 Ku band DBS xpndrs, all CONUS beam with mirrored spots of these xpndrs to HI and PR. All unused and unauthorized at present.

38 CONUS Ka band xpndrs (24 Ka-hi, 14 Ka-lo) with mirrored spots of these xpndrs to HI and PR of which up to 24 of any combo-mix can be active at one time.

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## PrinceLH (Feb 18, 2003)

I just hope that it won't require a whole new upgrade, with all new equipment. I own 3 of my 4 receivers and I don't relish having to have Directv owning all of my equipment.


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## peds48 (Jan 11, 2008)

well in foreseeable future you will need at least an HR54 and a C61K. If you own those, you are in really good shape. 


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## Drucifer (Feb 12, 2009)

peds48 said:


> well in foreseeable future you will need at least an HR54 and a C61K. If you own those, you are in really good shape.
> 
> Sent from my iPad Pro using Tapatalk


The way technology can suddenly change when something cheaper and better is develop, I would say nothing is truly safe.


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## peds48 (Jan 11, 2008)

Sent from my iPad Pro using Tapatalk


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## peds48 (Jan 11, 2008)

Drucifer said:


> The way technology can suddenly change when something cheaper and better is develop, I would say nothing is truly safe.


Hence "foreseeable" word was used.

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## Drucifer (Feb 12, 2009)

Diana C said:


> RDBS does downlink on the same frequency band that Ku uses for uplink (which is just below the current Ka downlink frequency). Since the downlink of RDBS is radiated out to the entire US, and the uplink of Ku comes from only a few discrete locations, and since the uplink uses highly focused antennas pointed at those locations, the potential for interference is fairly small. It is not zero, however, which is why DirecTV experimented with a small RDBS payload on the D-12 satellite. The experiments showed that there is no harmful interference.
> 
> *However, I would not get too excited about this "additional bandwidth" just yet.* I would think of it more as additional "potential" bandwidth. It highly unlikely that any existing LNBs can receive these frequencies (despite any speculation you may hear) since the capability is not on any LNB manufacturer's spec sheet. Therefore, wide spread use of RDBS for direct to home service is likely some considerable time off in the future. IMHO, it is most likely to be used for the delivery of 4k (aka SuperHD) content, since anyone subscribing to this service level would need new 4k capable receivers and, of course, 4k TV. These customers would very likely pay a premium for the 4k service. This is much preferable from DirecTV's perspective versus upgrading millions of existing customers just to deliver more HD.


The LNB took two years, but it is here now.

Now what will AT&T/DirecTV do with it?


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## slice1900 (Feb 14, 2013)

Drucifer said:


> The LNB took two years, but it is here now.
> 
> Now what will AT&T/DirecTV do with it?


Same as always....4K, plus probably mirroring CONUS content off 95 and perhaps 119.


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