Rainbow-1 Spotbeam TP Capability

[rocatman]

Questions about the capabilities of the Rainbow-1 (R-1) satellite have been raised especially related to spotbeam transponder (TP) useage. It has been posted elsewhere that R-1 has as many as 130 TPs but the question is how many can be used at one time specifically in spotbeam mode. I believe the limiting factor is power so what follows is a rough estimate of the power capabilities of R-1 based on some ancillary information and some assumptions that maybe totally erroneous but I have to start somewhere and you are welcome to flame if you must. Perhaps the invitation is not necessary on this forum.

First, here is a description of R-1 from the Gunter Space website (sorry, i didn't include a link because the link didn't seem to want to work):

"Rainbow 1 is a high power Ku-band*direct broadcasting satellite, which was ordered by Cablevision from Lockheed Martin, using the A2100AX bus. Cablevision remains very secretive about the details of this satellite. It will provide direct broadcast services across the continental United States (CONUS) from its final orbital location at 61.5° west longitude. The spacecraft features 24 MHz Ku-band high power transponders with a combination of 135 watt and 65 watt power amplifiers. The flexible design of the payload provides full interconnectivity to provide either all CONUS or all spot beam coverage through 22 individually programmable spot beams or a selectable mixture of both spot and CONUS coverage. The design life of the spacecraft is 18 years."

The two important items here are that R-1 is a Lockheed Martin A2100AX satellite and the 135 watt and 65 watt power amplifiers. I am assuming that the 65 watt amplifiers would be used for spotbeam TPs. The question here is whether 65 watts is enough power for a spotbeam TP. It should be noted that AMC-2 that is currently being used by Dish at 105 uses 60 watt amplifiers for CONUS TPs. Here's a link to the SES Americom website on AMC-2:

http://www.ses-americom.com/satellites/amc-2.html

Now back to the Lockheed Martin A2100AX satellite item. AMC-15 is also a Lockheed Martin A2100AX satellite that was built around the same time frame as R-1. Here's a link to the SES Americom website on AMC-15:

http://www.ses-americom.com/satellites/amc-15.html

Note that AMC-15 uses 140 watt amplifiers for the 24 Ku band TPs and 75 watt amplifiers for the 12 Ka band spotbeams. This gives a total of 4260 watts and assumes that all the Ku band and Ka band capabilities of AMC-15 could be used at the same time. Now I am interpreting the data here conservatively but one could interpret the data such that there are three 75 watt amplifiers for each of the 12 Ka band spotbeams based on the three subchannel data which would raise the total to 6060 watts.

As a sanity check, here is another quote from the Gunter Space website on the Loral 1300 series spacecraft.

"Total satellite power ranges from 5 to 12 kW continuously throughout the life of the spacecraft. On-board transmitter power — exceeding 5,000 RF watts — can accommodate as many as 70 active transponders. Launch mass tops out at approximately 5,500 kg."

I included the weight data because more TPs, amplifiers and the solar arrays to power them requires a larger, heavier spacecraft. The weight of R-1 is listed at 4238 kg and AMC-15 is listed at 4021 kg. As another point of reference, Echostar-8 a Loral 1300 series spacecraft is listed at 4660 kg. My conclusion from the weight data is that a good estimate of R-1 power is about that of AMC-15 perhaps slightly more but I will use the 4260 watts number to be conservative. 4260 watts divided by the 65 watt amplifiers allows for about 65 active spotbeam TPs. Again this is a rough estimate based on some assumptions but I think it gives a ballpark figure of the R-1 capabilities.

 

[James Long]

I do not believe that Lockheed would design or Cablevision would accept a satellite that wouldn't perform on all 130 planned spotbeam transponders at the same time. If they did intend on this type of use, they wouldn't have designed it with 14 spot uplinks. They would only need 6 uplinks for the 65 spot limit you suggest. (7 if they kept some TPs for ConUS - but that also reduces the power available for spots in your calculation.)

In any case, I don't see E* needing to light up all 130 spots ... and since it would require 14 uplinks to do that anyways it is unlikely to be tried in the near future.

Taken from the ITU filings:

Rainbow1 Spot Beams
R=Recieve Beam  E=Emit Beam  Satellite Receive and Emit
-----------------------------------------------------------------
Beam: R01                         Bangor          69.25W 44.90N
TP  1  3  7 15 17            E01  Bangor          69.25W 44.90N
-----------------------------------------------------------------
Beam: R03                         Bethpage        74.87W 41.06N
TP  5  9 11 13 21            E02  Boston          72.67W 42.76N
TP  1  3  7 15 17 19 23      E03  Bethpage        74.87W 41.06N
-----------------------------------------------------------------
Beam: R05                         Raleigh         78.02W 35.43N
TP  5  9 11 13 21            E04  Washington      77.56W 38.60N
TP  1  3  7 15 17 19 23      E05  Raleigh         78.02W 35.43N
-----------------------------------------------------------------
Beam: R06                         Atlanta         83.99W 33.67N
TP  1  3  7 15 17 19 23      E06  Atlanta         83.99W 33.67N
TP  5  9 11 13               E08  Charleston      80.45W 32.78N
-----------------------------------------------------------------
Beam: R09                         Miami           81.30W 26.96N
TP  1  3  7  9 15 17 19 23   E09  Miami           81.30W 26.96N
-----------------------------------------------------------------
Beam: R11                         Chicago         88.22W 41.51N
TP  1  3  7 15 17 19 23      E10  Detroit         83.55W 42.48N
TP  5  9 11 13 21            E11  Chicago         88.22W 41.51N
-----------------------------------------------------------------
Beam: R12                         New Orleans     89.44W 30.84N
TP  5  9 11 13 21            E07  Birmingham      87.43W 33.29N
TP  1  3  7 15 17 19 23      E12  New Orleans     89.44W 30.84N
-----------------------------------------------------------------
Beam: R13                         Minneapolis     94.57W 46.77N
TP  1  3  7 15 17 19 23      E13  Minneapolis     94.57W 46.77N
-----------------------------------------------------------------
Beam: R14                         St Louis        92.26W 38.52N
TP  1  3  7 15 17 19 23      E14  St Louis        92.26W 38.52N
TP  5 11 13 21               E15  Kansas City     96.49W 38.10N
-----------------------------------------------------------------
Beam: R17                         Houston         96.33W 29.27N
TP  1  3  7 15 17 19 23      E16  Dallas          98.29W 32.37N
TP  5  9 11 13 21            E17  Houston         96.33W 29.27N
-----------------------------------------------------------------
Beam: R18                         Denver         105.77W 40.41N
TP  1  3  7  9 15 17 19 23   E18  Denver         105.77W 40.41N
TP  5 11 13 21               E19  Albuquerque    107.20W 36.34N
-----------------------------------------------------------------
Beam: R20                         Seattle        119.63W 46.07N
TP  5 11 13 17 21            E20  Seattle        119.63W 46.07N
-----------------------------------------------------------------
Beam: R21                         San Fransisco  120.89W 37.93N
TP  1  3  7 15 17 19 23      E21  San Fransisco  120.89W 37.93N
-----------------------------------------------------------------
Beam: R22                         Los Angeles    115.34W 33.50N
TP  5  9 11 13 21            E22  Los Angeles    115.34W 33.50N
-----------------------------------------------------------------
Beam: RU1                    EU1  CONUS          103.08W 34.87N
TP  1  3  5  7  9 11 13 15 17 19 21 23
-----------------------------------------------------------------
Beam: RU2                    EU2  CONUS          103.08W 34.87N
TP 24
-----------------------------------------------------------------

JL

 

[mike123abc]

The advantage of uplinking under each spot of course would be that they would not have to pay for a bunch of fiber to send the signal back to a central uplink center. But, I do not think that the fiber costs are that high given the overbuilding of a lot of fiber networks in the US.

If they are 65 watt TPs in the spots and they ran all 130 at the same time, they would use a whopping 8450 watts! Perhaps they can run them at 30-35 watts each. This would give them enough power to run all 130 of them at the same time. Given the small size of the spots, they would probably have enough power. I wonder if Dish will give up more information on the satellite than the secretive CVC...

 

[James Long]

I wonder if Dish will give up more information on the satellite than the secretive CVC...

Has Dish told us the wattage and spot circles on E10? Rainbow made the map public in a filing related to the abandoned E*+D* merger (V* wanted ALL of 61.5 and E3 from the FCC ). Rainbow has also filed an accurate plan with the ITU, which helps. D*'s ITU filings don't specify all of the spot beam details.

As for R1 - In the ITU filings the spot emissions are described as:
Design. of emission: "24M0G7W--" Total power "8.8".
ConUS transponders are listed as "Total power 20.8".
They don't have the units listed, so I can't stay watts or dB.
(But I can sat the spots are considerably less power.)

JL

 

[SimpleSimon]

The advantage of uplinking under each spot of course would be that they would not have to pay for a bunch of fiber to send the signal back to a central uplink center. But, I do not think that the fiber costs are that high given the overbuilding of a lot of fiber networks in the US. ...

It's not the fiber - it's the uplink frequencies.

They are as finite as the downlink ones.

SO, you HAVE to have multiple uplink facilities, and I would not be surprised to learn that the spotbeam uplink uses the same antenna as the downlink, and so has to be in the same area.

 

[rocatman]

In regards to uplink sites, others have posted in the DirecTV Forum that the plan for HD LILs with the Spaceway satellites included having an uplink site for each local market.

In regards to the R-1 spotbeams, if the map from the Echostar Knowledge Base is accurate (http://ekb.dbstalk.com/pictures/rldbs1.gif), the spots are quite small especially compared to the E-8 spots and therefore require less power. Another factor though is error correction. With less power greater error correction is needed, reducing the number of channels/TP. I believe that with MPEG-4, up to 9 HD channels/TP is possible but this may have to be reduced for lower powered TPs.

Now looking at the spotbeam map from the perspective of providing HD LILs to the top 25 - 30 markets, spots E01, E07, E08, E12, E15 and E19 probably would not be used. Now if Dish could use E-1/2 at 148 for the west HD LILs, only 12 of the R-1 spotbeams would have to be used for the top 25 - 30 markets. Certainly there are other factors including carriage agreements that would affect which markets Dish would provide HD LILs.

 

[James Long]

if the map from the Echostar Knowledge Base is accurate (http://ekb.dbstalk.com/pictures/rldbs1.gif), the spots are quite small especially compared to the E-8 spots and therefore require less power.

That map is the one RainbowDBS filed with the FCC in their comments on the Dish/DirecTV merger. I'd say that it was accurate enough.

Note that most spots don't cover more than one other spot at any given point. R1's downlink TPs given earlier in this thread would work.

BTW: I do not expect spots 18-22 to be used. The look angle is just too shallow for a system that has other possibilities. They MIGHT be used as internal links to get stations to specific customers or uplink centers in the west. But I do not expect general customer use.

JL

 

[rocatman]

Looks like Dish may have use of at least some of the 129 W DBS slot that could give them more west coast capacity to complement R-1. See this thread:

http://www.satelliteguys.us/showthread.php?t=48987

In addition, I came across some additional power data specifically E-7 which is also a Lockheed Martin A2100AX satellite. Of course it is from a quite obvious place, the Dish website. It looks like 130 TPs at 65 watts is quite possible for R-1. Here's the link:

http://www.dishnetwork.com/content/aboutus/satellites/echo7/index.shtml

Besides the greater than 13 kW power, the weight of E-7 is a few hundred kilograms less than R-1.