Rain Fade observations

[Larry Acklin]

So we had a big extended downpour in W.PA last night. I had the chance to evaluate the various dishes I have set up in several different conditions.

I have a 10 foot c/ku BUD with a Co-rotor II, Dawn Satellite .8 Ku, Eagle Aspen C to a Toshiba analog, and slaved cband out to the Diseqc switch.

Also a Dish network Dish 500 (stock) seperate coax to a 322 receiver

And a 31" fortec with ULN1 from Sadoun pointed at AMC3 (87. W) for PBS. Through the Diseqc switch to a Mercury II receiver.

Heavy rain clouds overcast took about 5 points off the DBS dish- normally about 60, now 55.

PBS dish was Signal 80, quality 55- same deduction of SQ, not in strength.

The BUD on Ku gets about the same numbers on the PBS feed.

Then it started to rain, and rain, and rain (harder).

Lost the DN first, flipped over to PBS fixed dish, no signal at all. Went back to DN, had signal but only about 10. Went back to PBS dish, still no lock.

Rain abated some, got PBS back but not watchable. Went to DN, had lock, but only about 25 strength.

Then it almost stopped raining, but another strong storm rolled in- lots of thunder etc from the West- and lost things again. Note- no direct rain, just mondo clouds.

Next few minutes, things cleared up, back to watching.

When we lost signal again, I routed to the C/Ku dish, and had the same results (no lock) on Ku, but got good strength and picture on the Cband side of AMC3.

So- Rain fade is gonna happen at some point no matter what the dish, if you have Ku. C band seems to punch through. Also seems the moisture and cloud density had negative effects when the clouds were full of rain moisture.

I have an old aluminum solid X band dish I'm going to set up some day- but I bet it would not help Ku. My C band mesh dish with a commercial grade LNB still had problems with the monsoons we had last night.

On a positive note- 1500 gallons into the rainwater collection system (I have no city water)

Larry Acklin

[wejones]

I have found rain fade to be interesting too, and one complication to your experiment above, is that what I have found is that rain fade isn't so much caused by rain at your location, but seems to be caused by the water in the thunderheads, which may be 5 miles up, and 5 or more miles away from you.

I have always noted that if a storm is approaching that I usually lose signal before it actually starts raining, and usually by the time it's raining, I've got my signal back. Ie because of the above. I think the biggest cause of rain fade is not so much absorption by the rain, but scattering, so rain drops closer to you don't scatter as wide.

But relative to your experiment, the complication is that you're looking at signals on different satellites, ie the dishnet sats and the AMC3 PBS sat, and these 2 sats are in different directions, so it makes sense that things would happen at different times as the clouds are in line with the different sats. On my DTV, I get locals on 119, regular channels on 101, and I usually have my other dishes on AMC3, so when storms are coming from west, I usually lose locals first, CNN next, and PBS third, as the storms go past.

I often can tell where a storm cell is by whether my DTV goes out, or if my AMC3 goes out. If they are small cells, if my sat reception goes out, the storm will miss me to the south, but if it's a front line, it's just an indication that a strom is on the way.

[Larry Acklin]

Yep, thats what we saw- things did not drop out all at once. Sometimes we had better (worse) on one sat vs. the other.

If the local WX radar dudes bounce X band (or Ku ) off clouds and rain cells, and we get to see them on the 11:00 news, it follows that some of the energy from the sats would be reflected/scattered out of the path to us.

I'm glad my wife was watching a $1.99 PPV and not a $75 concert. (she was mildly annoyed at missing near 1/2 hr of the movie)

Larry

[wejones]

Originally Posted by Larry Acklin

I'm glad my wife was watching a $1.99 PPV and not a $75 concert. (she was mildly annoyed at missing near 1/2 hr of the movie)

..

Why watch PPV when Steelers were on? (I guess I just assume everyone in W.Pa. is a Steeler fan, even though some came from Ohio. )

[Larry Acklin]

Did that as the primary (multi)task. On CBS channel 2 (good ol' VHF). No rain fade there- prob. fiber or Cband to Pgh.

Larry

Stillers dominated the gamt to the point it was kinda boring.
But Tomlin got his first win as the new head coach.

[wejones]

Originally Posted by Larry Acklin

Did that as the primary (multi)task. On CBS channel 2 (good ol' VHF). No rain fade there- prob. fiber or Cband to Pgh.

Larry

Stillers dominated the gamt to the point it was kinda boring.
But Tomlin got his first win as the new head coach.

No chance of watching anything else here. Even my dogs watch the Steelers.

[lumpkin666]

Also worth noting is that you may see different levels of "rain fade" depending on the source of the satellite feed you are watching. You'll see rain fade on G10 when Arkansas (I think?) is getting pounded. Depending on how the weather is on the other end, minimal rain on your end may be just enough to cause signal drop-outs from a marginal unlinked feed. I wouldn't expect this to be a problem with Dishnetwork feeds since they probably have HUGE dishes and plenty of power to make their transmissions clear under the worst of conditions in their locations, but other sources may be susceptible to this issue.

[elgemcdlf]

So many vars. We had some serious rain last night and X4 (Ku) had no problems on the 8.5' dish and 4DTV receiver. G5 C band had a couple points where it broke up a bit but never lost anything. Could also be how well your alignment is for your location. It is a rare occurance when I lose the 8.5' dish due to storms unless it takes out the power

[Larry Acklin]

http://www.dishretailer.com/ts2001/4/MVC-021S.JPG

I think thats one of them.

[wejones]

Originally Posted by lumpkin666

Also worth noting is that you may see different levels of "rain fade" depending on the source of the satellite feed you are watching. You'll see rain fade on G10 when Arkansas (I think?) is getting pounded. Depending on how the weather is on the other end, minimal rain on your end may be just enough to cause signal drop-outs from a marginal unlinked feed. I wouldn't expect this to be a problem with Dishnetwork feeds since they probably have HUGE dishes and plenty of power to make their transmissions clear under the worst of conditions in their locations, but other sources may be susceptible to this issue.

I also often see storm problems (not so much rain fade) on my local channels on DTV related to the fact that DTV apparently has an OTA recever that receives all the local channels before they are uplinked to the DTV sats. At least I'm assuming that it's the OTA reception and not an uplink to the sats, because I'll see analog type static. But even though I'm sure Dishnet and DTV may have huge dishes for uplink to their sats, that doesn't mean that the feeds TO Dishnet/DTV have huge antennas.