Huh? What are the circles? What is this?

This is a map of DirecTV spot beams. To understand what the map is, there are some concepts I need to describe first.

DirecTV uses 32 transponders to broadcast signal across the country. Basically, each transponder is just a different frequency, carrying 10-15 channels on it. So, if you want to watch channel 8, your DirecTV receiver figures out which transponder carries channel 8, then switches to that transponder.

In an effort to squeeze more use out of transponders for local channels, DirecTV is now only broadcasting some transponders at some parts of the countries. This means what I see in Seattle on transponder 4 in Seattle will not be what someone in Boston sees. In other words, DirecTV is reusing the same frequencies for different parts of the country, just like what I get on FM 94.9 is not what you get in a different part of the country.

So, the main map is just an attempt to map where the various spots are hitting. Right now itís based off some initial guesses and assumptions about where the spots are, and sized to fit the data that I get from people across North America. The colors represent different transponders, or group of transponders, and defined by the key of the map.

There are two alternative views. One simply shows you one pin for each data point I have. The other is a more literal map of where the transponder strength is. Based solely off the data I have, it shows the strengths as theyíre reported across the country for each of the transponders.

(FAQ entry last updated: 8:00 AM 1/31/2002)

I'm in city x, does this mean I can get locals for city y?

I really donít know.

You can guess if youíll be able to by judging the size of the spot beam for whatever city youíre interested in. If it crosses into your territory, and you actually get readings that suggest youíre picking up that transponder, then maybe. Though, my maps are perfect, if youíre just on the fringe of the spot, you may or may not get it. It can also be difficult to tell what transponder is carrying the locals your interested in.

More than anything, donít ask me. I donít know. Really, I donít. I didnít make this map so people could ďmoveĒ around and get locals that they donít normally receiver. If you can use it to help you do just that, then great, Iím glad it helped. Iím not interested in helping you out though. Sorry, Iím not trying to be rude, but I might have a clue what the signal strength is in a given location, but I really donít know what channels itíll carry.

(FAQ entry last updated: 8:00 AM 1/31/2002)

Hey, I get signal strength of x. That means your map is wrong!

Yep, youíre probably right. My map is probably wrong. Now, enter your data!

As I get more data for more locations, Iíll be able to fine tune the size of the spots. Right now, if youíre on the edge of a spot beam, itís likely that the size for the spot has been misjudged slightly. The more data I have from people on the fringes of spots, the more correct itíll be drawn.

Also, as I get more data, Iím attempting to refine where the spots are drawn (not just the size). If you have concrete data that Iím drawing the wrong spot somewhere, or drawing two spots that should really be one, let me know. Please, donít email with guesses though. Iíve got plenty of those, and none of them agree with each other.

(FAQ entry last updated: 8:00 AM 1/31/2002)

Why don't you want all the transponders?

Not all of the transponders are being transmitted as spot beams. Only the six Iíve requested are being used for the spot beams. The others are being transmitted to the whole country. Given this, thereís simply no reason to collect the additional data, as I wonít do anything with other than toss it away.

(FAQ entry last updated: 8:00 AM 1/31/2002)

Can you give me some more links to information?

If you have any links you feel should go here, please email me.

(FAQ entry last updated: 7:46 AM 7/18/2003)

Why don't you use a better/different map?

A program of my creation draws the map Iím now using.

If you have any suggestions for a different size or area of the map, or any design changes, please let me know. Iíll see what I can do.

(FAQ entry last updated: 10:08 AM 2/9/2002)

I get different readings at different times, why is this?

From this page:

... This is bolstered by observations that some transponders have variable strength readings, particularly some are higher at nighttime and lower or zero in daytime. This is more likely due to varying radio propagation. The signals' Ku-band frequency (12.2-12.7 GHz) is quite susceptable to being affected when the sun's energy and magnetic field strike various layers of the Earth's atmosphere. The variations may bend or attenuate the satellite signals and easily account for the observations.

(FAQ entry last updated: 8:00 AM 1/31/2002)