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telcodad

join:2011-09-16
Lincroft, NJ
kudos:6

1 edit

It's Sun Outage time of year again

Just a reminder that we're entering the Spring "Sun Outage" period now.

This is due to the fact that the satellites that distribute TV programming are in "geosynchronous" equatorial orbits. Twice each year, during times near the spring and fall equinoxes, the path that the sun makes in the sky will pass behind the satellite.

When the satellite, the sun and the receiving antenna line up, once each day, the radio "noise" of the sun interferes with the satellite signals and can cause a "sun outage." These interruptions can last up to several minutes a day, with the "peak" days occurring in early March. The time of day of the outage varies with the particular location and satellite.

Here's a webpage about this on the Cablevision Optimum West site: »west.optimum.com/services/sun_outage

Edit: Changed the wording to "the path that the sun makes in the sky will pass behind the satellite" since from a point on the ground, a "geosynchronous" satellite will appear to stay at one spot in the sky. It is the sun's path across the sky that changes over time.



telcodad

join:2011-09-16
Lincroft, NJ
kudos:6

1 edit

I'm trying to predict which days and times that the sun outage will occur for my local Comcast system (headend is in Eatontown, NJ).

Assuming that they use Comcast's Headend in the Sky (HITS) (»en.wikipedia.org/wiki/Headend_in_the_Sky), then the satellites used are most likely either SES-1 (101 degs W) or AMC-18 (105 degs W). Is that correct? (This ignors all the other satellites that the Comcast Media Center in Colorado uses to get the various networks.)

If so, then plugging those into a Sun Outage calculator (like the one at: »www.satellite-calculations.com/S···calc.htm) along with the nearest listed location (USA - New York - NY), should tell me when I could possibly experience problems. What size antennas do most headends use? Do I also assume C-Band (4000 MHz) is used?

Edit: While the Eatontown location does have 2 satellite dishes and a tower with microwave and TV antennas on it, it may be that the actual satellite TVRO site is located in Toms River, NJ, and that feeds the Eatontown "hub."



telcodad

join:2011-09-16
Lincroft, NJ
kudos:6

OK, from what I can find, it looks like the SES-1 (101 degs W) and AMC-18 (105 degs W) satellites would be the satellites used, and a cable headend site could be using a 3.7 or 4.5 meter C-Band TVRO antenna, with a location near New York, NY for me.

Plugging all that into the Sun Outage calculator (»www.satellite-calculations.com/S···calc.htm) results in a sun outage period of March 1st through 6th (peak days - the 3rd and 4th), for a few minutes sometime between 2:00 and 2:30 PM EST.



DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:15
reply to telcodad

Since the various networks are distributed over several satellites, you'll see odd channels go out during those time frames.

See this page and surf through the individual satellites:
»www.lyngsat.com/america.html
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.



telcodad

join:2011-09-16
Lincroft, NJ
kudos:6

said by DrDrew:

Since the various networks are distributed over several satellites, you'll see odd channels go out during those time frames.

Well, yes, I assumed that the Comcast Media Center in Colorado has an "antenna farm" that receives all these networks from various satellites, and it then re-packages and re-transmits them to all the local Comcast headends using just a few satellites, using Comcast's "Headend in the Sky" service (»en.wikipedia.org/wiki/Headend_in_the_Sky).

This reduces the number of antennas and equipment needed at all the local headends.

While this means individual channels would experience sun outages at the CMC at different times, as you said, I figured that they would be much shorter in duration, as the CMC most likely has larger antennas (and better equipment). That is why I had said "this ignors all the other satellites that the Comcast Media Center in Colorado uses to get the various networks."

Since at the local headends the networks/channels are "concentrated" among fewer satellites, and their antennas are smaller, the effects of their sun outage(s) would be much more noticeable.


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:15

Most of the local headends just get their channel lineups by way of fiber interlinks between Comcast sites.

Comcast's HITS is a service normally used for other smaller cable ops.



telcodad

join:2011-09-16
Lincroft, NJ
kudos:6

4 edits

said by DrDrew:

Most of the local headends just get their channel lineups by way of fiber interlinks between Comcast sites.

That is what I think is the case with our local headend (hub?) in Eatontown, NJ. I believe it is fed by a larger headend in the Monmouth/Ocean County area, maybe in Toms River. (I say that because our Weather Channel "Weatherscan" service is from there.)

said by DrDrew:

Comcast's HITS is a service normally used for other smaller cable ops.

Are you sure about that? The article referenced in the Wikipedia entry on HITS (»www.multichannel.com/article/906···s_Up.php ) uses the term "cable affiliates," which I would think includes most of Comcast's own local (large) headends.

Edit: OK, well, I see from your profile that you must know what your talking about. I also found this item on the Comcast CMC website:

HITS Video Over Fiber
2010
»cmc-media1.precis5.com/914101ec4···f5a76f1f

"HITS, a business unit of the Comcast Media Center, today announced a national terrestrial fiber distribution service for delivering video programming to cable MSOs. The new solution is made possible by the cable industry expertise of the CMC, supported bytier 1 conditional access from Verimatrix and video processing and delivery powered by Harmonic Inc.

The new fiber service uses the expansive Comcast network to deliver video content to its HITS affiliates."

I didn't realize Comcast could use a fiber network to distribute all of those channels (SD & HD) to most of their headends across the US!


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:15

said by telcodad:

I didn't realize Comcast could use a fiber network to distribute all of those channels (SD & HD) to most of their headends across the US!

Comcast has ALOT of fiber. Beyond it's own video, data, and phone distribution network, they provide Business Class ethernet services up to 10 Gbps, cell tower backhaul, Media/Ad solutions (Comcast Spotlight), and it's HITS distribution.

BTW, HITS satellite distribution lineup here:
»www.comcastmediacenter.com/cmc-h···eup.aspx
--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.