Sirius signal loss due to sun position?

Baal · 2009-07-16, 07:47 PM

Can that happen?

Every morning this week I've been getting signal dropouts on my way to work, even though I drive right by the terrestrial repeater at Main & Catharine in downtown Hamilton, and never get more than 5km away from it.
This morning was the worst, as it dropped out briefly while I was stopped at a red light at Main & Hughson, about 200 metres from the repeater. Then the signal was gone completely by the time I was about 3km away.

But on my way home in the afternoon, the signal has been perfectly fine.

Could the sun position at this time of year and at that time of day cause interference? Or could the repeater be operating at lower power in the morning for some reason? I don't get it.

Anyone else ever noticed something like this?

MarcP · 2009-07-16, 08:09 PM

I noticed that when going to work in the morning, if I face a very specific direction at the same time every morning, the signal comes and goes. So it's always on the same stretch in the morning while driving to work. I soon as I turn on to another street, then I get a strong signal again. Not sure why as my antenna is on the roof and there are no tall buildings around.

trainwalker · 2009-07-16, 09:33 PM

This may relate to the morning effect you are experiencing.

I know that some AM stations in Canada and the US are required to turn down their effective radiated power at night due to the way the signal can travel to the stratusphere and bounce back down creating massivily extended broadcasting zones and interfering with other services.

However..AM is in KHZ and Satellite radio is around 1.5Ghz, if I'm not mistaken..

Just an idea.

Baal · 2009-07-16, 09:42 PM

Just to clarify, I've had Sirius for over 2 years now, and while there's been the random (and very rare) signal loss, it's only been this week that it's occurred in this kind of regular pattern.

Professor Frink · 2009-07-17, 01:03 AM

It isn't the sun, its the stupid figure-8 orbit of their satellites. Thankfully they have finally placed a geostationary satellite in orbit which when it goes in service should end the fringe drop-outs.

Canterbury Tail · 2009-07-17, 07:50 AM

The stupid figure 8 orbit (not a figure 8 orbit, just a highly elliptical normal orbit that transcribes a ground track that looks like a figure 8) of the satellites is there for good reason. It gives a much higher latitude coverage than a geo-stationary satellite, and costs about 1/2 as much to launch to those orbits. It gives better clearance of mountains and tall buildings as the signal comes down from a higher angle rather than a very low one. In addition it requires much less power for the satellite to broadcast from this orbit, thereby reducing it's size and weight, thereby reducing it's cost, thereby reducing it's launch costs etc. There's a reason XM got so horrendously in debt due to it's infrastructure.

Baal · 2009-07-17, 08:34 AM

Today's signal adventures:

6:30am - 7am: Solid signal in my apartment with no antenna hooked up (I live close enough to the repeater that I don't need an antenna there.) Cloudy/rainy conditions.
7am - 7:30am: Still at my apartment, occasional brief signal dropouts. Rain stopped, still mostly cloudy, but sun poking through a bit.
7:30am - 8am: Driving to work (normally doesn't take half an hour, but I had a couple of stops), a bit more sun poking through. Lots of signal dropout. Including as I was driving past the repeater. Then the last few minutes, with my distance from the repeater increasing, so did the cloud cover. No sunshine. And the signal was solid again. Checked my signal indicator and it was 10 bars terrestrial and 3 bars satellite.

JamesK · 2009-07-17, 10:45 AM

Quote:

However..AM is in KHZ and Satellite radio is around 1.5Ghz, if I'm not mistaken..

AM stations may be required to reduce power and/or change pattern due to skip which occurs at night. This skip does not affect VHF and above frequencies.

Baal · 2009-07-20, 11:35 PM

The anomaly seems to have passed.
Sunny again this morning, but back to a perfect signal.

Professor Frink · 2009-07-29, 10:59 PM

Quote:

The stupid figure 8 orbit (not a figure 8 orbit, just a highly elliptical normal orbit that transcribes a ground track that looks like a figure 8) of the satellites is there for good reason. It gives a much higher latitude coverage than a geo-stationary satellite, and costs about 1/2 as much to launch to those orbits. It gives better clearance of mountains and tall buildings as the signal comes down from a higher angle rather than a very low one. In addition it requires much less power for the satellite to broadcast from this orbit, thereby reducing it's size and weight, thereby reducing it's cost, thereby reducing it's launch costs etc. There's a reason XM got so horrendously in debt due to it's infrastructure.

And how much fuel is being expended to preserve the HEO orbits of Radiosat 1, 2 and 3? Once exhausted their out of business.

XM-3 and XM-4 have a good twenty years of service ahead left in them.

Canterbury Tail · 2009-07-30, 07:48 AM

No reason the fuel expenditures need to be high for that orbit, it doesn't come anything like low enough to require constant updating of the path due to atmospheric friction unlike satellites in an LEO. I think you should be more worried about constant crossing of the VARB than fuel for those satellites.

2009-07-16, 07:47 PM	#1
Baal Join Date: Sep 2007 Location: The Hammer Posts: 280	Sirius signal loss due to sun position? Can that happen? Every morning this week I've been getting signal dropouts on my way to work, even though I drive right by the terrestrial repeater at Main & Catharine in downtown Hamilton, and never get more than 5km away from it. This morning was the worst, as it dropped out briefly while I was stopped at a red light at Main & Hughson, about 200 metres from the repeater. Then the signal was gone completely by the time I was about 3km away. But on my way home in the afternoon, the signal has been perfectly fine. Could the sun position at this time of year and at that time of day cause interference? Or could the repeater be operating at lower power in the morning for some reason? I don't get it. Anyone else ever noticed something like this?

2009-07-17, 01:03 AM	#5
Professor Frink Join Date: Jul 2007 Location: Calgary Posts: 324	It isn't the sun, its the stupid figure-8 orbit of their satellites. Thankfully they have finally placed a geostationary satellite in orbit which when it goes in service should end the fringe drop-outs. __________________ Toshiba 40RV525R with HD-A3 HD-DVD, DSR505 and Xbox 360 Sportster 5 and Boombox with Best of XM

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2009-07-16, 08:09 PM	#2
MarcP Veteran Join Date: Nov 2003 Location: Airdrie, AB Posts: 2,953	I noticed that when going to work in the morning, if I face a very specific direction at the same time every morning, the signal comes and goes. So it's always on the same stretch in the morning while driving to work. I soon as I turn on to another street, then I get a strong signal again. Not sure why as my antenna is on the roof and there are no tall buildings around.

2009-07-16, 09:33 PM	#3
trainwalker Join Date: Sep 2008 Location: Shaw employee. My thoughts are my own and not my employers. Posts: 192	This may relate to the morning effect you are experiencing. I know that some AM stations in Canada and the US are required to turn down their effective radiated power at night due to the way the signal can travel to the stratusphere and bounce back down creating massivily extended broadcasting zones and interfering with other services. However..AM is in KHZ and Satellite radio is around 1.5Ghz, if I'm not mistaken.. Just an idea.

2009-07-16, 09:42 PM	#4
Baal Join Date: Sep 2007 Location: The Hammer Posts: 280	Just to clarify, I've had Sirius for over 2 years now, and while there's been the random (and very rare) signal loss, it's only been this week that it's occurred in this kind of regular pattern.

2009-07-17, 07:50 AM	#6
Canterbury Tail Join Date: May 2007 Location: Toronto Posts: 295	The stupid figure 8 orbit (not a figure 8 orbit, just a highly elliptical normal orbit that transcribes a ground track that looks like a figure 8) of the satellites is there for good reason. It gives a much higher latitude coverage than a geo-stationary satellite, and costs about 1/2 as much to launch to those orbits. It gives better clearance of mountains and tall buildings as the signal comes down from a higher angle rather than a very low one. In addition it requires much less power for the satellite to broadcast from this orbit, thereby reducing it's size and weight, thereby reducing it's cost, thereby reducing it's launch costs etc. There's a reason XM got so horrendously in debt due to it's infrastructure.

2009-07-17, 08:34 AM	#7
Baal Join Date: Sep 2007 Location: The Hammer Posts: 280	Today's signal adventures: 6:30am - 7am: Solid signal in my apartment with no antenna hooked up (I live close enough to the repeater that I don't need an antenna there.) Cloudy/rainy conditions. 7am - 7:30am: Still at my apartment, occasional brief signal dropouts. Rain stopped, still mostly cloudy, but sun poking through a bit. 7:30am - 8am: Driving to work (normally doesn't take half an hour, but I had a couple of stops), a bit more sun poking through. Lots of signal dropout. Including as I was driving past the repeater. Then the last few minutes, with my distance from the repeater increasing, so did the cloud cover. No sunshine. And the signal was solid again. Checked my signal indicator and it was 10 bars terrestrial and 3 bars satellite.

2009-07-20, 11:35 PM	#9
Baal Join Date: Sep 2007 Location: The Hammer Posts: 280	The anomaly seems to have passed. Sunny again this morning, but back to a perfect signal.

2009-07-30, 07:48 AM	#11
Canterbury Tail Join Date: May 2007 Location: Toronto Posts: 295	No reason the fuel expenditures need to be high for that orbit, it doesn't come anything like low enough to require constant updating of the path due to atmospheric friction unlike satellites in an LEO. I think you should be more worried about constant crossing of the VARB than fuel for those satellites.