Why does Sirius "blank out" for a few seconds?

This is more a curiosity about the science of satellite radio, as I only lose my Sirius connection for one or two seconds – but it’s always in the same spot on my way to work.

Gremlins? Entering a brief space/time warp?

Are you going under a bridge? Or past an especially tall/thick stand of trees? Big building(s)?

well, it’s dependent on whether your radio has the “Sirius” chipset, or the “XM” chipset. back before they merged as SiriusXM, they had separate satellite systems which orbited differently. Sirius uses 3 satellites in geosynchronous orbit, which “wander” north<->south (see image.) XM’s satellites use geostationary orbit, and are more or less “parked” in one spot near the equator (image.) I’ve seen that in certain areas at certain times of the day you might find a “dead” zone as the satellites wander around.

Ever since the merger, SiriusXM has been pushing its customers (meaning integrators and OEMs, not listeners) to the XM “band” due to a few reasons, sound quality being one of them. I’ve found as I’ve gone from a car with a Sirius band radio to one with the XM/SiriusXM band I’ve had fewer signal interruptions.

to add, if you experience the drop-out in the same physical location every time, there could be something like there just being a “dead” zone, or something nearby causing reflections/multi-path. Their data streams have pretty robust error correction, but too high of a bit error rate will cause the receiver to mute for a brief time rather than playing pops, clicks, and other potential nasty noises.

I nearly always get drop-outs on my Sirius radio when I’m driving through downtown Milwaukee on I-94 / I-43. It doesn’t seem to me like the buildings in that area are tall enough to block line-of-signal to the satellites, so I’ve always assumed that there’s something in the area that’s creating an interfering signal.

actually I have to walk part of that back- the stream is encrypted, so too many bit errors will cause a decryption failure thus a short mute.

Because he’s mid-transition to Padfoot?

Awesome! :smiley:

We have two vehicles that both have Sirius. I have driven both to work, on the same route, and one loses the signal at the same three spots every time (including my office parking lot). The other vehicle has no signal issues at all on the same route. I’m guessing they have different chipsets.

Here’s how you can tell- if the brand attached has the “XM” logo or the “SiriusXM” wordmark, it’s the newer XM chipset. if it has the Sirius “Dog” logo, it’s the old one.

plus, the antenna itself is critical. it’s a “patch” antenna which relies on the roof/decklid of the car to act as the antenna’s ground plane. differences in antenna design and implementation might lead to performance differences.

Happens to us on the way to church. The buildings are no more than seven stories high (about as high as a building oughta go). I suspect MiB is headquartered somewhere in downtown Suffolk, Virginia.

Interesting stuff, all!

I have a BMW “shark” antenna.

I can’t tell you why it happens but I can vouch for the issue too. I have a 30 mile one-way commute and my Sirius radio goes silent in the exact same 3 spots back and forth every single time. It only last 2 - 3 seconds because I am going fairly fast but it is annoying. I have tried to figure out what might be causing it but there is no obvious cause. One spot is about 1/5 of a mile past an overpass but the other two are just open interstate highway without anything but trees on both sides of the road. I am not saying it is aliens but…either that or definitely military.

Back in the late '80s and early '90s my husband worked in a military radar facility. Some nights when he’d pass by the building the rear windshield wiper on his VW GTI would mysteriously turn on. Creepy.

a “shark fin” antenna is typically just a housing, and inside are the AM/FM, satellite, and GPS (if equipped) antennas.

doesn’t surprise me. electronic modules back then weren’t as immune to induced RF as they are today.