# Signal Dropoffs: XM vs. Sirius?



## PT1

Howdy everyone! New guy here, and not technically oriented at all, so thanks for your patience. I got Sirius installed in my car last week and am troubled by the signal dropoffs. They are never that long--a few seconds at worst--but they do mess up my enjoyment of the broadcast. A quick Google search seems to suggest they are more common with Sirius than with XM: Is that your experience, or is the problem similar with both? What concrete solutions are there? I had a good company do the install; I'm sure they'd be game to try anything I suggest. Or should I switch over to XM? Or just make my peace with the dropoffs? (I get them in good weather, and over open sky, just FYI, so I can't blame trees or clouds.)

Thanks for your expertise!


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## blmoore

I've had Sirius since the beginning, and have never experienced what you have, except when I had a receiver die. I would get a signal drop every once in a while, then the frequency increased until it didn't work any more.

You mention there are no obstructions present when this occurs, and I assume that means tall buildings as well. Both Sirius and XM have ground repeaters in larger cities to take care of this issue.

If buildings aren't the issue, then I'd have the installer re-check the connections, and perhaps try another radio. You might have just gotten a bad one.


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## trh

If you are having signal drops in open areas, I'd guess that you have an install problem. Where did they mount your antenna?

With both XM and Sirius, you will get signal drops under certain circumstances; tunnels, overpasses, parking garages, tall buildings, and sometimes trees. Most of the radios have a built in buffer, so you don't always lose the signal.

My Sirius receiver is a factory installed unit in a Ford. I don't think it has a diagnostic screen. My XM Inno has a menu where I can check the sat signal strength to see how strong of a signal I'm receiving. You should check to see whether your radio has a similar screen and check your signal strength.

And Welcome to the board!


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## PT1

Thanks; I'll ask about the position of the antenna. What's the optimal position?


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## trh

I've read the manuals for five different plug-and-play sat radios. They all say the roof is the best place for cars (highest and no obstructions). I have one installed on my trunk deck right now w/o any problems, but I live in the south. Same mount location in the north might have more drop outs (at least on XM). I know some people that have their antennas on their dash and they don't seem to have a problem with reception. 

But if you're in the open and have problems with drop-outs, there is most likely something wrong with install/antenna.

Switching from Sirius to XM? I am certainly biased towards XM, but since the merger, about the only thing different between the two (IMHO), are the sports that each carry. NFL and NASCAR on Sirius; MLB and NHL on XM. I'm not sure who carries soccer or the NBA, but something you might want to check before you consider a switch. These days, the music on each is almost the same. Oh, XM has Opie and Andy and Sirius has Howard Stern.


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## PT1

Thanks; good advice. I am going back to the installer and will ask about position of antenna and tell them about the dropoffs.

From my Google searches, I see that a bunch of people mention signal dropoffs being a problem with Sirius. I am happy with the programming (only interested in music, and it is the same with XM). I considered switching only for the possibility of better signal pickup.


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## trh

I've read the debates about which service has more drop outs. But I have XM and Sirius right now and don't see any difference in drop outs. You're going to experience some drop outs with both. But from own experience (3 vehicles with Factory OEM Sirius and 3 XM plug&plays installed in 4 different vehicles), I wouldn't rate either one better than the other when it comes to drop outs.


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## PT1

Thank you for sharing your experience. You've saved me from a big complicated and fruitless step (switching providers).

Do you have any experience with changing the position of the antenna to decrease dropouts? Has ANYthing helped?

Thanks again; all your experience is very helpful for me.


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## mlb

I have sirius in 1 car, and xm in another. XM has many more dropoffs than Sirius, in my situation. I took the XM car on a trip earlier this summer, and due to the tall trees I kept losing the signal. I took the same trip last summer and had no issues with the Sirius receiver.


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## PT1

Very interesting. Thanks for sharing your experience. Sorry we're all in the same boat, but it's at least it's reassuring to learn that my decision to get Sirius wasn't completely boneheaded.


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## trh

PT1 said:


> Do you have any experience with changing the position of the antenna to decrease dropouts? Has ANYthing helped?


Where is your antenna located? Top of the vehicle is best (and most recommend 3-6 inches from the edge, but I've installed all my plug & plays right at the edge w/o any problems).

The ONLY drop outs I've experienced, can't be fixed by moving the antenna: overpasses, tunnels, parking garages and some trees.


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## Alebob911

I have sirius in my Mercedes ML350 that is factory installed and a Kenwood radio with sirius and I get drop outs all the time. I was told that sirius does not use ground repeaters and that XM does so that could explain the issue. I went to SF and lost signal while in and around the big tall office buildings. We never had issues like this when we had XM. With Sirius you have to have sight to the "heavens" to get a signal.


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## trh

Alebob911 said:


> I was told that sirius does not use ground repeaters and that XM does so that could explain the issue. I went to SF and lost signal while in and around the big tall office buildings.


Whoever told you that isn't well informed. From Sirius.com FAQ page:


> While we do have an extensive network of ground repeaters (towers that rebroadcast our satellite signal to help give maximum coverage) in many metropolitan areas, factors such as microwaves and physical obstruction (bridges and tunnels) can still temporarily disrupt your radio's reception.
> 
> However, this problem is largely held at bay by the four-second buffer created by slight broadcasting delays between our two satellites orbiting over the continental United States and our extensive ground network of repeaters.





Alebob911 said:


> With Sirius you have to have sight to the "heavens" to get a signal.


Same is true with XM unless you have ground repeater coverage in your immediate area. Tall buildings impact both XM and Sirius.


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## Alebob911

Guess I'm in an area that have no or limited ground repeaters.


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## trh

Alebob911 said:


> Guess I'm in an area that have no or limited ground repeaters.


I have a Ford with a factory installed Sirus radio and two other cars with XM radios that I installed (Inno and SkyFi2). I don't get dropouts on any of these unless I'm going slow under an overpass, am in a tunnel or a parking garage. And I'm too far away from any ground repeaters.

You may have a hardware problem (radio or antenna wire).


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## wilbur_the_goose

There IS a difference between XM and SIRI in this regard. When you drop off in SIRI, you get a "skip" where you lose 2-5 seconds. You lose the same info on XM, but you get a "hiss" sound when it happens. (obviously, I have one of each, but prefer XM)


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## PT1

Do you get more dropoffs from the hissy XM or the skippy Sirius? I am interested in the comparative number of dropoffs.

As for WHERE IS ANTENNA INSTALLED: There is a wire in my trunk, near the hinge, that wasn't there before, so I assume that's the antenna, or leads to the antenna? Should I have them try to reinstall it in the front of the car? Could that help?


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## trh

PT1 said:


> As for WHERE IS ANTENNA INSTALLED: There is a wire in my trunk, near the hinge, that wasn't there before, so I assume that's the antenna, or leads to the antenna?


What type of car do you have and where is the antenna installed?

I've had XM since 2001-2002 and Sirius since 2006. Because the signals come from satellites and it is a LOS system, you will get dropouts. But I wouldn't say one is better than the other (in reception).

Is that wire in the trunk being pinched?


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## PT1

Toyota Corolla, 1996. 

As for that wire being pinched: I don't know what happens to it when I shut the trunk. I can only see it when the trunk is open. It's more like a thin rubber tube almost; not a wire.

I drove today for about 45 minutes, and had a good 18-20 dropouts. Now I was driving in an area with lots of tall trees around, but still. That's too much. I can't enjoy this.


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## PT1

trh: Thank you for your many generous replies. You've been great with your time and expertise and experience.


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## Davenlr

Dont mount the antenna on the trunk. Mount it on the roof, run the thin antenna wire under the windshield rubber molding down into the engine compartment and in through one of the firewall rubber grommets.

Sirius uses several satellites that orbit in a north/south pattern, XM uses two satellites in geostationary orbit (much much higher). Depending on your latitude, one might be better than the other. The satellites for XM are at 50 degrees elevation here in Arkansas. Sirius ones move, so they could be anywhere from overhead to lower (Unless sirius changed in the past year since I read up on their sat system).

In all cases, the rooftop is the only place on a vehicle where part of the vehicle wont block the signal at certain inclines and directions. Highly recommend a rooftop mount.

Ive got XM, and a roof mount, and drive about 100,000 miles a year, all over the state (mountains, lots of trees), and the only place I ever get a dropout is when I go through a tunnel, or drive for an extended period of time on the north side of a mountain cut where the mountain is higher than 50 degrees to my south, and there arent that many of those.

Good luck.


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## PT1

Thanks Davenlr. I am taking it back to the installer tomorrow. I'll report back.

(Hope I don't hear "We can't install it on the roof in your model of car...")


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## trh

PT1 said:


> I drove today for about 45 minutes, and had a good 18-20 dropouts. Now I was driving in an area with lots of tall trees around, but still. That's too much. I can't enjoy this.


Trees can impact reception. But this still sounds excessive. Roof mount best. You said in your first post you get dropouts even when in the open. So if you're driving on the interstate do you get dropouts? If so, you need to go back to whoever installed your radio and have them check it out.

What radio do you have? Have you tried the diagnostics or looked at sat signal strength?

No problem with the help. I'll feel better though when your problem is fixed. We made two 16-hour round trips to the FL Keys this summer (vehicle with Sirius). Only dropouts were when we parked under metal awnings at gas stations. Also one trip to NY - 37 hours total driving (vehicle with XM). Only dropout was going through the tunnels in Baltimore. Its great being able to select a station and listen to it as long as you like.


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## PT1

I have the technical abilities of Paris Hilton. Let me ask my installers about these issues.--antenna location, signal strength, diagnostics. I did like them very much, and trust them to make this work for me. 

You all have been great; thank you, again, for validating my suspicion that this is not performing up to snuff.

It's a shame, because I am very happy with the music programming. I'd hate to have to give that up.


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## trh

Let us know the outcome after you go back to your installers.


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## PT1

Unfortunately, I had to pick up a relative at the hospital, and wasn't able to get to the installer today. I was hoping to return with a post of triumph today! Thanks again, everyone, for all the good advice and guidance. As soon as I can, I will update you.


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## PT1

trh said:


> Let us know the outcome after you go back to your installers.


Sorry for the long delay. Just got back from the installers. They moved the antenna to the exterior--specifically, to the inner edge of the trunk lid exterior. On the way home, I had only two brief signal cut-outs: going under bridges. I'm fine with those. I drove home through a neighborhood with a heavy tree canopy, and no cut-outs. So I may have an improvement here! I'll keep you up-to-date as I rack up more miles and listening hours with the exterior-mounted configuration. Thanks again for all the great background info and suggestions. This forum is full of smart folks. Special shoutout to satellite wizard TRH.


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## trh

Glad we could help you. You still may experience drop signals because the antenna is located on the trunk. If you do have drop outs without heavy trees, tall buildings or bridges, move the antenna to the roof. Good luck and enjoy your satrad.


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## PT1

Thanks TRH. Now I am starting to wonder why the antenna was installed inside in the first place (I guess it was in the trunk). I just watched the Sirius installation video, and they never mentioned an inside antenna installation.

I don't know why they chose the trunk instead of the roof for the exterior mount. Maybe they didn't want to go to the trouble of inserting it into the rubber weather stripping around the rear window?

So far, so good though. I just drove again for about 45 minutes and didn't lose the signal.

If I get more drop offs and decide to go for a roof installation, I am going to take the car to my mechanic, whom I trust. I'm giving up on this installer.

I'll keep you posted if there's any change or complications.


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## PT1

Just moved the antenna to my roof. I notice that my installers did not use the 3-inch tail for the antenna, referred to in the installation instructions. The tails appear to be difficult to find via Sirius, though I see them online. They are to keep the antenna surrounded by at least three inches of metal on all sides. Does anyone use theirs? Has anyone noticed a difference in reception between following the 3-inch rule and not following it? Right now, my antenna is close to the back edge of the roof--maybe 3/4 inch. Thanks.


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