True Visions

[Pib]

Thanks again for sharing your knowledge.

I thought that I'd better check the signal strength before messing around with the dish myself.

Today is a bit overcast, but no rain, and checking the signal strength on the menu, I see

Locked 255

-33 dBm

I will check again when clear skies to compare. What should I expect, around -26 ?

That sounds about right, but the reading will vary some depending on the power measurement accuracy of your settop box, length of cable from LNB to settop box, whether you are using a power splitter or not, etc. I've got one box that gives me around a -33dbm reading and the other box (different make) gives a -13dbm. I switch the box around and I still get the same reading which tells me the power is equal down each cable, but each box is giving a different power read out. But if I remember right, once the power signal drops by around 15 db (say the -33dbm going to a -48dbm) I will lose the signal.

Most of the KU band settop boxes are rated for a power input from -25 to -65, which is their best operating range. It would be nice if the boxes would work down past a -48db but as mentioned above both boxes give the Low Signal/Searching for Signal after the LNB input drops approx -15db from normal/clear sky output. I've even put a 20db amp in the line...while it increases the power level by approx 15-20db, I still lose the signal when the LNB power output to the boxes drops approx 15 db from normal/clear sky. Maybe, I'll try a new LNB but my gut is telling me it probably won't help.

[moo9]

Hi,

The rainfade problem is more pronounced in Thailand due to the low angle of the satellite. In most other countries the line of sight to satellite is a lot closer to vertical, but due to the vast array of Thaicom's other cutomers, the satellite is not positioned over Thailand but at some other more economical point. This means that the signal has a much longer path to travel en route to your dish and is hence more prone to rainfade, trees, birds and other things which may block the signal path.

The angle is not flat at all, as we are close to the equator.

I agree, disalignment of the dish due to winds and maybe improper installation, low quality coaxial cable. Usually a 70 - 75 cm dish would be ok. Back in Europe people use 65 or 85 cm. But in tropical thunderstorms the clouds reach much higher and are weakening the signal much more.

I had UBC years ago, and always had probs during heavier rain showers.

[Pib]

Curiosity quesitons: Does anyone out their have a 11300MHz KU band LNB mounted on their "C Band" dish? If so, did it improve you reception during rainfade conditions over the TrueVisions 75cm dish? 11300Mhz is the LNB LO frequency used on TrueVision 75cm KU system/dish.

Although I have the TrueVisions 75cm dish, I also have a C band dish/system. I'm thinking about swapping out my "dual output C band LNB" with one of the "dual output C band and single output 11300Mhz KU band LNBs" which cost about 900 Baht. I would run the C band LNB outputs to my C band receivers as now and run the KU LNB output to my TrueVision system--basically taking the 75cm TrueVisions dish/LNB out of the equation.

According to specs on a 6 ft C Band dish and 75cm KU band dish, I should see approx a 7 db gain from the C band dish. I know I could keep my current C band LNB and just attach a 11300MHz LNB just to the side of the C Band LNB, but I want the 11300Mhz LNB exactly in the center of the C band dish for best gain...plus I can use the removed C Band LNB on another project I'm thinking about.

Edited June 3, 2010 by Pib