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What is the difference between Sirius and XM technology? I know they are now one company, but here's the reason for the question…

In 2009, my wife's Audi Q5 came with Sirius Satellite Radio and a free 90-day trial subscription. We sampled Sirius/XM, liked a few channels, but both felt the "audio quality" was poor (at best), and the constant signal drop-outs were annoying. Trial period ends, we did not become paying subscribers.

Fast forward to this year. My Carrera GTS arrives with XM Satellite Radio and, once again, a free 90-day trial. Sound quality is actually very good (on the exact same stations as before). Drop outs are almost nonexistent, even going through tunnels(?). Trial period ends, and I signed up for a year's subscription.

So, it's gotta be the satellite receivers themselves, right? Does XM have a technological edge over Sirius? Certainly the XM radio has a much bigger signal cache than the Sirius set. Or, is the difference I've noticed simply a function of Audi audio versus Porsche audio?

Surely, someone on this forum knows the hows and whys of the two satellite systems' set-ups.

Right now, to me, the XM radio seems superior to the Sirius radio. And the difference is significant.

CodeRed

They both are pretty lousy in my cars. More importantly did you get PDK or a 6MT?

Spectro28

I've compared the XM in my '10 997 with the XM in my sister's '10 Scion Xb and the Sirius in my wife's '11 Ford Fiesta.

XM in my 997 is worlds better sound quality than in my sister's Scion - go back and forth between XM and a CD in my sister's car, the difference is shocking. Not XM's problem.

Sirius in the Ford is really really good. That Fiesta with the Sync package is impressive sound quality and tech.

Not a Sirius v. XM problem, I believe. A radio problem, maybe antenna problem too?

Cheers,
Marc

403portside

We have an '11 q5 and I think satellite sounds great. Dont have it in my 997 to compare against.

Mike in CA

Our new 2011 A3 TDI also came with the free 90 day Sirius trial and an upgraded Bose sound system. The Audi MMI accepts SD cards onto which I'd previously copied a bunch of MP3 audio. The point is, I can instantly switch back and forth between sources using the receiver and media buttons so it's easy to compare. Sirius is very close to the quality of MP3; I'd say it's quite good. I have noticed some dropouts in areas that are overhung with lots trees, but in general reception is good too. Maybe the difference you've experienced is more between the 2009 and 2011 vintage equipment than between Sirius and XM.

jhbrennan

Pre-merger, XM and Sirius used different satellite technology, different number of satellites and different positioning of satellites - I don't know what has transpired post merger. I've had XM and Sirius both pre- and post-merger in different cars and really never noticed any sound quality differences - since I mostly listen to news I doubt I'd notice. But reception is another issue - my Sirius receivers (one with an external antenna in a M5 and one with an internal antenna in a 997) always lose the signal for a couple of seconds during my morning commute while driving south and when I go under an overpass. I never lose the signal in my Suburban with an XM reciever. I'm sure there are more knowledgable folks who can discuss the other technical differences.

mdrums

I have XM with Bose in my Cayenne S and I mostly listen to NASCAR and NFL and some Comedy and those stations have sound quality of AM radio. The music stations are a tad better but not as good as FM radio and no where near CD quality.

I've had XM and Sirrus in various cars over the past 7 years and the audio quality is not good. Reception in my General Motors (GM) auto's has been stellar. I've had better reception in other auto's I rent while on business trips than I get in the Cayenne but I rarely get drop outs.

texas911

When XM was independent, they employed ground repeaters to boost their signal so that you could still get XM without line of sight of their satellite. I don't know if they still have them, but in your case it seems like they kept them on in LA.

RudyP

I have aftermarket XM in my 997 and have just ordered a car (2012 Mustang GT) which will have Sirius so I will be able to compare directly. No real complaints about XM in the 997 although it does occasionally lose signal for 1-3 seconds - sometimes seemingly randomly (ie no vertical obstructions). I also have XM in my airplane and that has been flawless and high quality. Never a drop out either but then again, I don't tend to fly under obstructions. The qualiy of the signal seems the same between car and plane on XM.

Minok

XM and Sirius satellite constellations are different, and their frequencies are different. Now that they are one company, that doesn't mean they replace the satellites, those are still the same. They can be reconfigurable to some extent in terms of signal but not likely for position.

So while you may build receivers now that could lock on to either system, that would make the receivers more expensive and the antenna may be specific to a certain freq. range.

The quality of the sound depends on two things:

1) the compression used - which is all XM or Sirius. They decide how much to compress the audio and how many bits and bitrates to give a channel. So for talk based content, mono-AM quality is fine. For music, you want stereo with more bitrate, but compression is still noticable.. thats the buzzing/tinny sound of the music. They could reduce compression, but have to give up channels because the total link bandwidth is fixed.

2) The receiver. That playback device controls how much buffering it has and how it handles flakey signals as well as how it decompresses the data stream. You cannot totally compensate for a period of lost signal with buffering, because the signal comes down from space as real-time data. So if you drive into a tunnel and loose data feed from the sky, until you come back out, all that data is gone, missing. You cannot, once you get the feed locked on again, go back and get the data you were missing.

If the receiver had the ability to buffer, say 10 seconds of data, so it could play 10 secs more after loosing signal, you may come back out of the tunnel before it runs dry, but the system still has to then splice your current listening to the new live stream. It could buffer that new stream, but there will be a gap of content you don't get.. so it will sound like skip at best. One could play back a bit more slowly from the buffer, to stretch its content out, but you cannot compensate for that missing data.

But a higher end expensive head unit could do a much better job than a lower end cheap unit at dealing with that break in the data stream.

So you need to compare not only the sat network (Sirius v XM) but also the electronics (receiver, amp, antenna) in the car.

rtraviator

I have XM in my 06 Ridgeline and it sounds great. My 09 C2S with Bose sounds good, though I may be somewhat biased as I'm not in the least a fan of Bose equipment. Both lose signals when line of sight (LoS) is lost with the southern sky. I don't recall the number of satellites (I believe 3) in a geosynchronous orbit above the equator, but it's not enough to support all the programing they offer, IMHO. Lastly I have some indoor/outdoor speakers hooked up to my 1978 Kenwood receiver for my garage that also has an XM radio as an Aux input and it ROCKS!

Bullit

Minok, this is the best explanation I have seen....thanks for taking the time to write.