SiriusXM S-band Reception

[Old2New]

The question is, "how is it possible to receive SiriusXM radio S-band geosynchronous satellite signal without dish and LNB"? Apparently, SiriusXM receivers utilize short wire omnidirectional antenna, and it seems S-band signal strength would be inadequate.

The SiriusXM marketing info says their receivers combine three separate signals, two identical S-band signals from neighboring satellites but with one delayed by 4 seconds from the other, and a third signal from terrestrial repeaters that are fed by a separate Ku-band satellite (AMC-6), received by Ku-band dishes, and rebroadcast locally across N America.

The Wikipedia "Sirius Satellite Radio" article, perhaps written by SiriusXM marketing, mentions a complex chip set of up to six ASICs.

My suspicion is this is largely BS, and all the SiriusXM receivers are only receiving the terrestrial repeater broadcast.

 

[harshness]

SiriusXM has repeaters only in some of the larger metropolitan areas. There are entire regions that aren't covered. Here's an older map (2010?):

SiriusXM has reportedly shut down more than a few (if not all) of these repeaters since 2010.

They obviously can't be serving Bozeman or Peoria from a repeater. More than a few of the repeaters were located in tunnels and existed only to serve the interior of those tunnels.

If they can draw five or more GPS satellites into a wristwatch, they can certainly grab a couple with a much larger SARS antenna.

SiriusXM operates in a relatively low frequency band (S-band) that is 1.97-2.69GHz which gives it pretty bulletproof atmospheric penetration in addition to the entire satellite platform (SSL-1300S) powering only one transponder. This frequency band is not far above that of GPS that runs around 1.2-1.6GHz.

Don't let the fact that you can't get your head around something lead you to believe that it can't possibly be happening.

 

[Scott Greczkowski]

I use to have a SiriusXM repeater on top of my building but it was shut down a few years ago.

On the older radios you use to be able to go in and see the satellite signal levels. They are definitely coming off of satellite.

 

[Old2New]

SiriusXM has repeaters only in some of the larger metropolitan areas. There are entire regions that aren't covered. Here's an older map (2010?):
View attachment 181640
SiriusXM has reportedly shut down more than a few (if not all) of these repeaters since 2010.

They obviously can't be serving Bozeman or Peoria from a repeater. More than a few of the repeaters were located in tunnels and existed only to serve the interior of those tunnels.

If they can draw five or more GPS satellites into a wristwatch, they can certainly grab a couple with a much larger SARS antenna.

SiriusXM operates in a relatively low frequency band (S-band) that is 1.97-2.69GHz which gives it pretty bulletproof atmospheric penetration in addition to the entire satellite platform (SSL-1300S) powering only one transponder. This frequency band is not far above that of GPS that runs around 1.2-1.6GHz.

Don't let the fact that you can't get your head around something lead you to believe that it can't possibly be happening.

Thank you. The explanation that the entire SSL-1300 platform power of ~10KW is powering only a single transponder answers my question.

 

[aegrotatio]

By the way, the Ku-band repeaters are only on the Sirius side of SiriusXM. The XM side's repeaters takes the strongest signals from the main S-band satellites and rebroadcasts them on the terrestrial band.

The XM side of SiriusXM is better in just about every way. The one thing that made the Sirius side better was the use of satellites in high-altitude polar orbits which made the need for repeaters on Sirius way much less than what was required for consistent reception on the XM side.

Now, of course, those Sirius polar satellites have been shut down for years, crippling the Sirius side since it has so many fewer repeaters than the XM side and SiriusXM is chomping at the bit to shut down the Sirius side.

 

[aegrotatio]

Thank you. The explanation that the entire SSL-1300 platform power of ~10KW is powering only a single transponder answers my question.

On the XM side, each satellite powers two transponders: one is aimed primarily at the East, the other at the West. The Western satellite does the same. That makes a total of four transponders serving the continent.

As for your comment about SiriusXM marketing posting about ASICs on Wikipedia, there are two receivers per each of three bands on an XM (not Sirius) radio for a total of six receivers on the three bands. The Sirius receivers only have three receivers. It's a subtle feature that makes the XM receivers so much better at receiving reliable signals.

 

[harshness]

Now, of course, those Sirius polar satellites have been shut down for years, crippling the Sirius side since it has so many fewer repeaters than the XM side and SiriusXM is chomping at the bit to shut down the Sirius side.

The term you were looking for is "tundra orbit" rather than "polar orbit". Tundra orbits spend considerably more time in view of a particular hemisphere.

 

[stogie5150]

The question I wanna know is, has anyone acquired an S-band LNB and hooked it to a computer? Inquiring minds wanna know. If its ONE transponder, we satellite guys could hit that with a pie plate.

 

[harshness]

The question I wanna know is, has anyone acquired an S-band LNB and hooked it to a computer?

Don't you suppose that with all of those hundreds of channels, there might be some serious encryption and modulation going on? SiriusXM had enough trouble trying to make a single radio that would handle both schemes, what makes you think a computer could do it in software?

 

[arlo]

S band is pretty active actually. It really doesn't take more than a patch, helical antenna. Either with or without a reflector to focus the signals. A search for s band reception comes up with a lot of info.
The now defunct Outernet and now Othernet was easily receivable using just a ku band lnbf and no dish and didn't take a very accurate aim to receive. But I guess that's all dead now. Slow data rates, a lot of data buffering and error correction and all that stuff that's above me.
But receiveing sxm and doing something with it are two things. The TSOP chip is their secure lock. I read way back in the day of people piggy-backing a radio chip on a sat receiver chip and cloning it. Interesting, yeah. But.

 

[Scott Greczkowski]

The question I wanna know is, has anyone acquired an S-band LNB and hooked it to a computer? Inquiring minds wanna know. If its ONE transponder, we satellite guys could hit that with a pie plate.

Its actually two transponders.

I would think a LNB would be TOO MUCH for the SiriusXM signal, as its so strong and it also bounces off things. If you had the electronics to receive the S Band you could probably see those transponders using something like a paper clip on a scope. (But again it would need other things for the frequency to tune to.)