Sattelite Dish Positioning.

[gennisis]

I am in Chiang Mai. My existing True dish gives me excellent picture quality....but against everything I have been told,it is directly in line

with a group of fairly thick trees. less than 5 meters away..,,,certainly no direct line of sight..and.. in theory should not be getting such a good signal... I am not complaining,just bemused...so can anyone explain?

I ask because if I go with CTH I understand that the dish will have to be repositioned approx 1/4 turn to the south and at a lower elevation,where tall trees are more like 15 meters away. and I have been told the CTH signal will be weaker than the True one

I appreciate that the installer will have a meter to determine the best sighting...just a little worried in advance.

[Gsxrnz]

When True installed my dish they didn't have a position locater. One bloke was up the ladder, the other was inside watching the strength meter on the TV, and they yelled good, bad, better worse etc to each other as the bloke outside moved the dish around. Very comical - took them 30 minutes and then when they had it correct the bloke on the ladder dropped his spanner and couldn't lock the dish in place. Another 30 minutes........

While in theory trees do have a detrimental affect on satellite reception, it's been my experience that the impact is minimal and I've had trees in the way as well as a tin roof of a residential building, and also a neighbours house (brick) in the way. Never had a problem.

I think the real killer is ferro concrete.

[Satcommlee]

The actual signal comes down at an angle of 57.9 degrees in Chaing Mai, although the dish may be appearing to point more like 30 degrees, so the trees may not be interfering at all.

Also they transmit a lot of extra signal to help reception when it rains, that why most peoples signal levels show up at 99% o 100% when they check the signal on the menu's

What is your signal according to the menu's?

Edited June 4, 2013 by Satcommlee

[pattayadingo]

I too had a true dish set up at the back of a house with the back of another house there overshadowing the dish that should have been blocking the signal but it worked fine.

If and when the CTh set up does come into play and you do not have someone to align the dish you can ask people at CAT or TOT who often are willing to aim your dish or they know someone who can. I had 2 lads from CAT Telecom come along and align one dish for me for 200 Baht.

[joncl]

because True uses offset dishes they are really looking 24 degrees higher than they appear too ..

[Satcommlee]

because True uses offset dishes they are really looking 24 degrees higher than they appear too ..

I am often asked this question but I don't know the answer, is that the true offset of these TV antennas as a rule?

[monty]

All offset dishes are not at the exact same offset angle. Normally the spec sheet of the dish will state the offset, and the actual looking angle is normally indicated on a scale on the swiveling mounting of the dish.

An offset satellite dish is easily recognized by the fact that the receiving head (lnb) is not positioned at the center of the dish.

You can compare this to looking in a mirror when standing at an angle, you are then not looking at yourself, but away at an angle.

The vinasat satellite CTH is supposed to be going to use actually has pretty good power. Transponders on vinasat with similar settings as transponders on Thaicom will have the vinasat ones come through much better.

However what it will be for CTH channels will depend on what settings they will use for the transponders, a bunch of HD channels eat up a fair amount of bandwidth, so they often use higher SR and/or a different FEC, which heavily influences the received quality of the signal.

[Satcommlee]

All offset dishes are not at the exact same offset angle. Normally the spec sheet of the dish will state the offset, and the actual looking angle is normally indicated on a scale on the swiveling mounting of the dish.

An offset satellite dish is easily recognized by the fact that the receiving head (lnb) is not positioned at the center of the dish.

You can compare this to looking in a mirror when standing at an angle, you are then not looking at yourself, but away at an angle.

The vinasat satellite CTH is supposed to be going to use actually has pretty good power. Transponders on vinasat with similar settings as transponders on Thaicom will have the vinasat ones come through much better.

However what it will be for CTH channels will depend on what settings they will use for the transponders, a bunch of HD channels eat up a fair amount of bandwidth, so they often use higher SR and/or a different FEC, which heavily influences the received quality of the signal.

All offset dishes are not at the exact same offset angle. Normally the spec sheet of the dish will state the offset, and the actual looking angle is normally indicated on a scale on the swiveling mounting of the dish.

An offset satellite dish is easily recognized by the fact that the receiving head (lnb) is not positioned at the center of the dish.

You can compare this to looking in a mirror when standing at an angle, you are then not looking at yourself, but away at an angle.

The vinasat satellite CTH is supposed to be going to use actually has pretty good power. Transponders on vinasat with similar settings as transponders on Thaicom will have the vinasat ones come through much better.

However what it will be for CTH channels will depend on what settings they will use for the transponders, a bunch of HD channels eat up a fair amount of bandwidth, so they often use higher SR and/or a different FEC, which heavily influences the received quality of the signal.

I see no allocations for CTH yet? if they are not using a complete transponder or part of a complete transponder MUX they will be considerably weaker than Thaicom plus the added rain attenuation factor due to lower attenuation.

[Pib]

I don't know if I would say 24 degrees would be a rule of thumb figure but many satellite parabolic offset dishes fall in the 22 to 25 degree offset ballpark. For example, at this Link a variety of Jonsa dishes ranging from 65 to 120cm in size..all have a 24.62 degrees offset angle with the exception of the elliptical 85cm dish which has a 17.94 degree offset....an elliptical dish is one that is significantly wider than it is tall.

[lor]

I installed satellite dishes for years. Trees, or more correctly leaves, can block a signal completely! But as other posters have pointed out. In Thailand Thaisat is very high in the sky (almost straight up) and even though the dish looks like it may be looking at the trees because the dish is offset it is really looking much higher and over the top of the trees.

Chris

[Pib]

Below diagram might help in understanding that an offset parabolic dish like used by TrueVisions is actually looking higher into the sky/receiving satellite transmission (say that approx. 24% higher mentioned in an earlier post) than what your eyes are telling you.

[pattayadingo]

Below diagram might help in understanding that an offset parabolic dish like used by TrueVisions is actually looking higher into the sky/receiving satellite transmission (say that approx. 24% higher mentioned in an earlier post) than what your eyes are telling you.

offsetparabolic.JPG

The eyes do not always tell the truth.

Good graphic to demonstrate what the dish really looks at and explains why the house behind me caused so few problems.