Signal strength survey for 80 cm dish for G3 and IA5

[William Eng]

I am trying get a sense of what signal strength others are getting for G3 and IA5. For me, G3 varies between 50-60% and IA5 varies between 40-50%. Most of the time, I get a perfect picture, however, when there's bad weather around, the picture breaks up. Results from the survey will help me decide whether or not to spend an afternoon of more fine tuning. I got the Sadoun's M1 system. Also does anyone have any experience with the rain spray that Sadoun sells for $25/can?? How much improvement can one expect?? Here in Florida, the afternoon rain comes down in buckets...and the signal goes down to almost nothing... maybe I need a bigger dish??

[boroda1]

I think you may specify, what receiver brand do you have.
I am getting a quality reading ranging from upper 60s to 94% on IA5,
but this is in "Coolsat" units, where quality reading below 65% means pixelation, and below 60% it's a total loss.
For G3, tp 11780H, quality reading is about 90% too

P.S: I would not mind if you send me some rain, it's 100°F right now

[lostinthewoods]

On my system Pansat 2700A, HH120 Motor, an old Prime Star dish, QPH-031 LNB and located in mid west GA,

"I think every response should be for the same transponder, I suggest 11867 V
on IA5 . Transponders vary in their output."

My signal strength is 77%
Quality 72-76%

(edit to be consitant on TP used as requested)

Lost

[brentb636]

I think every response should be for the same transponder, I suggest 11867 V
on IA5 . Transponders vary in their output.

My signal strength is 84%
Quality 68-70%
Located in mid-Michigan

[rainman]

on that transponder quality is 75 to 80%.

[wejones]

I'm surprised that no-one has said this, but in my opinion, it is a waste of time comparing signal strength and quality readings. All systems give different results, even if you are comparing the same transponder, even if you are comparing the same brand receiver. A 30/30 S/Q reading on one receiver may be excellent while a 60/60 on another receiver may be poor. Even with the same receiver and the same aim, S/Q can change dramatically depending on which version of firmware you have in your receiver. S/Q can change depending on your length of coax, depending on whether you've slaved your receiver, depending upon interactions with other receivers or computers in the system. There are so many variables involved that it is really a waste of time to compare numbers like this.

There was also a question about rain fade here. With marginal Ku dishes, this is a fact of life. I've never tried the spray mentioned, although I'm skeptical. In my experience, anything around the dish can be ignorred. I've even put a sheet of plywood between my lnbf and the dish, and still get reception (attenuated of course, but it demonstrates the relative effect), whereas if you put that same sheet of plywood out 5' or more in front of the dish, I completely lost signal. The reason is that the major effect of water is scattering, and the longer the distance from the dish, the more effect scattering has. THe main cause of rain fade is the actual thunderhead, which may be 5 miles away and 5 miles high. I get my worst rain fade when it isn't even raining, but is raining 5 miles away. The only remedy for rain fade is a bigger dish.


Anyway, back to signal level comparisons, I have 3 DVB receivers connected to the same signal. None are comparable to this discussion because I have a very dented/warped 10'dish, but on one receiver I get 80/90 readings, on another receiver I get 35/40 (which is excellent for that receiver). On the 3rd, the readings are somewhere in the 65-70 range. All looking at the same signal at the same time. One of those receivers gives the following spectrum for the IA5 vertical (vertical=center wire for Steve's cable system ) .



Notice that my baseline is declining from left to right, which is caused by line loss in my 250' feedline. Signals to the right are lower signal strength wise, but are actually better, signal to noise wise, again showing how signal strength is really meaningless when looked at by itself. In this trace, the baseline, near the left lower freqs is near a 46 reading, which is higher than the peak signal level on my other receiver, ie no signal at all on one receiver shows up as a higher signal reading than an excellent signal on another receiver. AGAIN..... signal strength comparisons are meaningless.