Interactive Beam Footprint Library

I'm assuming that the color rings indicate the dish size needed in order to access the signal...did I miss the posting that shows the color legend.

 

spears61 is the spotbeam expert.
the old document did have a legend for the rings.
I cannot find my original notes but reviewing the data i believe the center point is 0dB gain or the predicted EIRP of the beam in question.

the rings are power losses from the center
White = -2 dB
Blue = -4 dB
Green = -6 dB
Pink =-8 dB
Yellow = -10 db
Orange = -15 dB
Red = -20 dB

This does correlate with the size reflector/ dish needed for adequate reception but is not indicative of specific size needed.

My "ballpark" guesstimates are that inside the Pink ring is adequate for standard slimline dish reception.
Outside or approaching Red ring may push the limits of the DTVAH 1.2 Meter dish.

Maybe others can give exact dB conversions /explanations.

Doctor j

 

These sites can give more insight.
Assume center point 59 to 60 dBw and rings reduce as above.

http://www.kvh.com/Pages/Satellite-Coverage-Maps/Satellite-Coverage-Maps/TracVision-Maps.aspx

http://www.sadoun.com/Sat/Installation/Dish-Size.htm

KA reception may need 1 or 2 "steps" up in size to prevent serious "minor" weather problems.

Doctor j

 

Each satellite is unique in that the Maximum dBw strength at the center point will vary. And each filing may have different ranges. But, in general, the filings are for 0, -2,-4,-6,-8, -10,-15, and -20

Remember, a 3dBw change reflects a factor of 2, either double or 1/2 signal strength and you are working with logrithmic data so you either add or subtract to calculate totals ; ie a change of 6 is equal to a change by a factor of 4 for absolute signal strength.

You will find the dBw level somewhere on each isodBw bar east or west of the center point. The macro runs thru the data points and places the digital data point at the first location within +/- 2 degrees latitude of the center point as it increments thru the lat/long points for each curve.

I prefer to use the left side panal to open the index. The center point, and all curves are labeled by both color, name, and dBw number in that panal (all done automatically by the Google Earth guys).

Mix and match satellites, beams, and dBw levels by toggle to get a view of you area.

Remember. A standard Directv antenna probably will have solid reception for anything above 50 dBw.

 

Trying to understand the maps and getting a bit confused. I'm in the South San Francisco Bay Area, but I see two D3 spot beam maps: one for San Francisco (D12 A2BD) and one for San Jose (D12 A3BA). I'm certainly closer to San Jose (a few miles) than San Francisco. What Spot Beam would I be receiving HD locals from then?

Only reason I'm asking is because the San Jose spot beam seems to be pointed farther east with a pretty strong signal in Lake Tahoe...not that that particular piece of information is germane to the question.

The San Francisco spot beam is clearly farther west, with a very weak (if not receivable) signal in Tahoe.

Thoughts from you experts out there?

 

I looked at the DC spot beam and there are multiple ovals. Can you tell me what each one represents?

I will be traveling to Blacksburg which is inside the the 2nd inner oval. Does that mean I can get local channels from DC?

 

The data for El Paso is interesting. I was out there for a couple of months. When I returned to Tucson, I was getting 90% siginal. I'm now in Phoenix and I can still get a 50% signal out here. The maps show it a dead signal before it crosses the Arizona border.

 

The maps show the signal strength isobar as spears 61 explained above.
This represents the likely signal from 2 or 3 TPN's on that beam.
If you are seeing signal on a certain transponder, may be from another beam.

Put them all on a map and see the overlap.

The actual output of any transponder is adjustable and subject to change.
What is happening at this moment can only be measured by those in the beam and reporting variations.

It is a logrithmic scale of wide variability.
The digital tuner has an ON or OFF threshold.

Doctor j

 

You also may be looking at the wrong map.
The "El Paso" map in post #8 above references the BSS band on D-12 not currently known to be active.

As per :
http://www.dbstalk.com/showthread.php?t=195415

El Paso is on D-11 Beam A3B9
There is no "map" per se but extrapolate D10-12 Beam A3B9 (Tucson) 200 or so miles to the NE and you have the facts as I know them.

This suggest Tucson would be along the yellow isobar and "borderline".
Phoenix would be along the orange to red isobar and not likely to be "available"

Doctor j

 

Where do I find Mobile, AL/Pensacola/FT Walton, FL.? I do not see them.

 

Mobile, NET 639 MKT 128 is on D-11 Beam A2B7

Again no exact beam map , but use D-10_12 Beam A2B7 (New Orleans) map and shift about 200 miles directly NE.
Centers about Biloxi!

Doctor j

 

Thanks doctor... As a kid, the trick was seeing what kind of distant signals I could get on AM. Could barely hear anything, but I always checked at the top of the hour for call signs. Now, I see those signal strengths on spot beams and wonder where there headed to. Can't do anything with the signal, but it's interesting just the same.

 

DrJ I see you are a relatively close neighbor. Have you had any experience with the spotbeam for the Bham area outside the state lines? I didn't find the information for our beam in gct's posts. I have a service address in the Bham area but I am currently traveling in the New Orleans/Baton Rouge area. I have signals at or near 100 on the 101 and 90's on all others except 99s. At least one TP on 99s is near 100 but the 21 TP that serves the HD Bham stations is at 0. I did get as high as 33 on the 22 TP for a short while and the DVR picked up a recording from the PBS station on the 22 TP about midnight on a clear weather night. The signal on the 22 TP seems to be only late at night. Is there any chance more alignment tweaking would improve my chances of recieving my Bham locals? I realize I am probably asking for a miracle here but the fact I found PBS and The CW gives me hope. I contacted D* CS and blew their mind with my complicated question. I was offered a form to recieve East Coast DNS . I am using a SL3 dish and HR24-200.

 

Wow, I think I have finally found what I have been looking for. About 8 months ago I started living full time in an RV and I travel about the country. I have a Winegard slimline traveler HD auto sat dish on the roof with Directv HD service. I haven't applied for DNS as I don't really want to pay the extra monthly cost. So far, I have had success with calling DTV and having them change my service address, but I spent six weeks in Myrtle Beach and 4 months in one location of Florida. I am under the impression that DTV won't change my locals too often but I haven't gotten a good line on just how often I can or can't change them. I view these maps as a way of selecting service address location that will keep me within the footprint of spot beams that generally correspond to my travels. For example, I plan to slowly travel this spring/summer up the east coast and into the Canadian Maritimes. It looks to me that if I first chose DC it would cover me from about NC up through NY. And then if I gave a Boston service address, I would be good for NY on up into Canada.

Do I have this all correct?

 

Data looks good.
There is a Question about 2 Panama City Beams , they are exact copies and thus one suspects a duplication error omission of another close by.

The west spots are somewhat larger ie Salt Lake City, Amarillo, Oklahoma City, Portland OR, Reno.
I can see a redristribution if these become available.

Doctor j

 

I noticed that also. It looks like some rural customers may get their HD local channels back, albeit they'll have to wait a year and a half.