friggin' snow...

[wad]

had a repair the other day......

hn9000, 1w, .74m antenna, with no sqf inside. so i put the terminal into repoint and headed out to the reflector. i put my dapt in line and had a receive sqf of 2-4. as i brushed off the snow and ice, i watched the sqf climb right up to 189. it needed no resquinting, so after flying thru the dapt, i went back in to give the customer the good news.....if it doesnt work after a snowstorm.....BRUSH IT OFF!

on a side note, im noticing that the ka is MUCH more sesative to snow build up than ku. i can honestly say that a ku would have been working with the amount of snow that accumulated on it. sorry i didnt grab a pic though. anyone else seeing this as well?

 

[grohgreg]

If this is your first winter as an installer, I can tell you from years of experience that it doesn't take much wet snow or slush or ice accumulation to kill a satellite connection - especially if it's allowed to collect on the feedhorn. Don't matter if we're talkin' Ka-band or Ku-.

Dry snow's a different animal though. The reflector - and even the feedhorn - can be completely obscured by inches of dry snow, with little or no effect on signal strength.

//greg//

 

[wad]

no ive been at it for 8 years now, im VERY familiar with cold and snow. its obviously just the first with the ka, as it came out in what april? but all we get over here is the wet suff, lake effect off of ontario. im hearing similar stories from our techs though......snow KILLS the signal, like it never did on ku.

 

[grohgreg]

Well, no insult intended - but your observation makes sense if you have no experience with dry snow. But now I can't help but wonder if your complaint might be transmitter-related. Otherwise I can't imagine why there hasn't been a bigger howl from the (receive only) DirecTV customers on Spaceway 1 and 2

//greg//

 

[HCI]

Well, no insult intended - but your observation makes sense if you have no experience with dry snow. But now I can't help but wonder if your complaint might be transmitter-related. Otherwise I can't imagine why there hasn't been a bigger howl from the (receive only) DirecTV customers on Spaceway 1 and 2

//greg//

Would not be transmitter related if he did not have a signal, the transmitter is disabled if the LNB is not receiving a signal. Most of the time the simplest solution is usually the correct one. The KA band is just way way more sensitive. I installed a dish last week and there were high winds, I am talking about blowing me off the roof. Just the flexibility of the dish from the wind gust's was dropping the signal 50 to 75 points. This also made pointing and squinting extremely difficult.

 

[grohgreg]

Apples and oranges. The transmitter doesn't energize until the modem sends it something anyway. What I am trying to suggest is that WADs Ka-uplink may be more susceptible to snow attenuation than is his Ka-downlink. Now if this issue is in fact universal, it's an engineering flaw. But if it's localized, it could be low modem output, excessive IFL loss, a weak transmitter. Or how about maybe the feedback loop is providing bad input for the adaptive uplink?

I'm pointing this out, because as an engineer I don't believe this is a Ka- versus Ku- issue. Dry snow attenuation for both bands is minimal. And heavy rain/wet snow/slush/sleet/ice affect both without prejudice. So as I suggested before - if it's really the SQF problem you suggest, don't you think there'd be a lot more outcry from the Spaceway 1 and 2 customers?

//greg//

 

[HCI]

Apples and oranges. The transmitter doesn't energize until the modem sends it something anyway. What I am trying to suggest is that WADs Ka-uplink may be more susceptible to snow attenuation than is his Ka-downlink. Now if this issue is in fact universal, it's an engineering flaw. But if it's localized, it could be low modem output, excessive IFL loss, a weak transmitter. Or how about maybe the feedback loop is providing bad input for the adaptive uplink?

I'm pointing this out, because as an engineer I don't believe this is a Ka- versus Ku- issue. Dry snow attenuation for both bands is minimal. And heavy rain/wet snow/slush/sleet/ice affect both without prejudice. So as I suggested before - if it's really the SQF problem you suggest, don't you think there'd be a lot more outcry from the Spaceway 1 and 2 customers?

//greg//

Do you work for Qualxserv?

I quote "with no sqf inside. so i put the terminal into repoint and headed out to the reflector. i put my dapt in line and had a receive sqf of 2-4. as i brushed off the snow and ice, i watched the sqf climb right up to 189. it needed no resquinting,"

and

"im hearing similar stories from our techs though."


Not sure why we are going around and around on this.

 

[grohgreg]

Do you work for Qualxserv?....

No, and there's no need to get adversarial about this. I'm a retired telecommunications engineer with satcom experience dating to 1973. I was first introduced to milimeter wave (now known as Ka-band) way back in 1984. I know propagation characteristics - strengths and weaknesses - across the entire communications spectrum.

Not sure why we are going around and around on this.

Because I want to correct your misconception that Ka-band is more susceptible to snow than is Ku-band. It is not. I merely made an opening statement that snow affects both Ka-band and Ku-band the same. Specifically; neither are bothered much by dry snow, both by wet snow/slush/ice. You'll find volumes of technical data to support this as both a propagation property and an electrical property. But then you jumped in with "The KA band is just way way more sensitive". It is not.

So I attempted to explain that - if uncharacteristic sensitivity to snow attenuation is a systemic issue with all HN9000 installations - it's an engineering fault on the part of Hughes. But if the occasions are local, look for local causes. The frequency band is not responsible.

//greg//