I have created a set of Excel Worksheets to correlate which Spotbeam is broadcasting into each DMA LIL (Local Into Local) market.
There is a large amount of data that went into creating this project; it may seem overwhelming at first glance but I wanted to explain the process so it can be useful to all in a number of ways.
One might reasonably ask, “Why?” Or “Who cares?” I'll address this first. As the HD LIL rollout is finishing its 6th year, with more than 50 DMA's still awaiting HD locals, I see many questions:
1. Why aren’t channels available in my market?
2. If I have some channels, why not all?
Another burning question is that some larger western DMA's HD LIL's were available then "turned off", reportedly because the entire zip code area of that DMA wasn't able to be serviced by the applicable spotbeam. This may be a topic to explore further, but I need some outside help to search and document specific events.
Some of this data comes from assumptions: I'll try to explain where possible. But most data comes from sources within DBSTalk and from references to public FCC documents.
THE TPN MAPS
My saga starts with the Transponder Map data that is found here:
I've been fortunate to work for almost 2 years on this project and understanding the AGP/PID data stream got me to asking more questions, such as those above.
I have also been interested in LIL markets and channels ever since Detroit came online 10/2005 and followed newshawk's/bamaweather's thread here:
BEAM FOOTPRINT MAPS
The spotbeam Google Earth maps were amazing and the recent update to the interactive format allowed me to manipulate the information to find patterns. Those spotbeams are here:
ANTENNA AND BEAM MAPS
So I thought, why not try to put them all together!
After a long study of the FCC documents and reviewing the data I was already collecting, I realized that the 49 spot beams of D10/12 and D11 had a set pattern of:
Antenna 1 = TPNs 16/19/20 Beams B1 to BC
Antenna 2 = TPNs 15/23/24 Beams B1 to BD
Antenna 3 = TPNs 17/18 Beams B1 to BB
Antenna 4 = TPNs 21/22 Beams B1 to BD
This is outlined well in The FCC document Exhibit 43 of D10's LOA and Grant:
I then sorted my data by TPN, then DMA and cross referenced each Spotbeam (I numbered the beams 1-13 (as opposed to the hex #'s B1 to BD) and created a set of 8 worksheets: (4 Antenna worksheets for D10/12 and 4 Antenna worksheets for D11) each correlating DMA/channels to Spotbeams A*B1 to A*BD.
We do not have a full set of spotbeams for D-11 because the FCC file size limitations at the time of D10 and D11 FCC filings. A key was to recognize that D12 and D10 were almost identical and the full set of beam data was available from D12's LOA/Grant:
We have corresponding beams A1B1, A1B7 and A1B9 from D12 and D11. Mapping the D11 beams, they line up 200 miles northeast of the D12 corresponding beams. I assume this to be true for all 49 beams. I confirmed that the D12 A4B5 Jackson, MS beam moved 200 miles Northeast covered my DMA, Birmingham, AL and indeed 99S TPNs 21 and 22 are my highest spotbeams, giving apparent validation to my assumptions.
We can get an idea regarding capacity and local area availability of LIL channel space. Our approach does not assume any "hold back" for redundancy, assuming 110 TPNs are available to each slot (99W and 103W). The technical data in Exhibit 43 maps 6 uplink sites. Site 1 is the Los Angeles Broadcast Center (LABC) and has one LIL uplink set.
The other sites S2 to S6 have two uplinks sets (national channels not repeated). Site 2 is Castle Rock, CO (CRBC). Sites 3, 4, 5 and 6 in no particular order are NEUF, MWUF, SWUF and NWUF. Thus there are a total of 11 reproductions of the 10 spot TPNs available for 110 total LIL TPNs per orbital slot. They are allocated three (3) TPNs per beam on Antennas 1 and 2 and two (2) TPNs per beam on Antennas 3 and 4. Not all 49 beams can be active at one time. The theoretical maximum is 123 TPNs. Technically only 105 are listed on the schedule S technical data report but I see no reason that 110 is not the true maximum.
Looking at the spotbeam set one can see that the Havana, New Orleans (actually centered in the Gulf) and Marfa, TX beams can easily be skipped since they don't correspond to populated areas. Several other beams can fall out as well.
I have begun an initial attempt to understand the Spaceway satellites but the "infinite" variability of the 1500 element phased array antenna makes exact projections difficult. Review the Spaceway technical data, Exhibit D here:
I found the Spaceway satellites are capable of any combination of up to 24 spotbeams. The D12 utilization of the A band for 16 Conus TPNs on 103 has reduced the LIL bandwidth to 6 (3 sets of R/L) TPNs. Assumed to be wider that D*'s 36 MHz Maybe 62.5 MHz, or to correctly fit into remaining bandwidth, some combination between 36 MHz and 62.5 MHz. Beam size is a minimum of 0.5 degrees and is adjustable in 0.5 degree increments. Quick geometry gives a 0.5 degree beam 22,236 miles above the earth’s surface a diameter of approximately 200 miles. This seems a comfortable fit with the spacing I assumed.
So here it is!
I have provided a document of 10 excel sheets: 4 forD10/12, 4 for D11 and one each for SW-1 and SW-2. I have placed a couple of rough outlines of what SW spotbeams probably look like.
The lookup process is the same as that used for the TPN Map data:
DMAs are identified by their DIRECTV NETWORK numbers, ranging from 512 to 723.
In the TPN Domestic Map, LIL Market List Page, note DIRECTV NETWORK (NET) number. The LIL TPN map will tell you which Satellite your SD and HD (if available) channels are on.
Scroll through the worksheet to find the Satellite and Antenna as appropriate. (This is dictated by TPN as noted above). The spotbeam will be given in the Beam column and you can look up the interactive Spotbeam reference.
Download the appropriate GoogleEarth Beam Footprint display. You of course must have the GoogleEarth application installed. Not all D11 spots available. Use corresponding D12 files and remember that D11 beams are centered approximately 200 miles to the northeast.
My disclaimer is that I am not a communications scientist. I am open to all comments and hope this information will encourage dialog to help us understand more of the DIRECTV Satellite System we enjoy.
This Data is from 7/14/2011 Download.
The Spaceways are undergoing a LOT of re-balancing/market/transponder shifting. I'll update when shifts stabilize.
A great deal of thanks and inspiration goes to gct, psmith, newshawk, bamaweather, spears61 and all at DBSTalk!
Edited by gct, 01 August 2011 - 05:38 PM.