Eutelsat 10/9 reception - or not

brother9

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(Continued from "Missing frequencies on Hispasat 30W):
Right. I am still here....
As you can see on this last photo of TRIAX dish, behind it is an oval dish (90x65) aimed at 13° E. LNBs on 28°E, 23°E, 19°E and 13°E give excellent (Quality) signals: up to 99%. AND I have one LNB for Eutelsat 10 and 9. I was watching programs on 6 TER Suisse AND e.g. Kurdistan. BUT:
The 9+10 signals disappeared. Could have been moved during winter storms. I have 2 cables going into the house, 2 Diseqc switches, (and a cable switch in TV room,) changed the LNB, changed the cables to Diseqc box, re-aimed LNB, etc. HOWEVER:
I never get the signals from Eutelsat 10+9 as previously. Station 12BBC2Delay is coded but has 44% signal. ZAGROS has 66% - sometimes. I have been up the ladder 100+ times.... YES, good signal (80%) on Zagros, nothing on 6 TER. Next morning: NO signal at all..... Towards evening: Zagros 45% then 0%, etc.
Can anyone tell me what is up? Have satellites moved? Have their power(s) been reduced? Have their footprints been changed/moved? All my LNBs are black. WHY?? Do they not get VERY hot with (lately....) full June sunshine for 19 hours!?
Remember, I HAD both satellites on ONE LNB in the past.....
Thank you.
 

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I doubt you see 19 hours of sun a day.
 

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Do you get better signal when it's cooler? Make something to shade the LNB if you think it's the sun affecting it. How did you adjust the LNB - did you try changing the angle of the arm or move the LNB in & out? I have a similar looking multi-LNB rail and the individual LNB holders like to 'walk' along the rail, presumably related to heat cycles.
 

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I doubt you see 19 hours of sun a day.
On "weatherforecast for aviation" it says sunrise 03.04 UTC, sunset 20.18 UTC. Longest day, so that indeed makes 17 1/4 hours of sunshine on the LNB. (OK, not 19 hours).
 

brother9

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Do you get better signal when it's cooler? Make something to shade the LNB if you think it's the sun affecting it. How did you adjust the LNB - did you try changing the angle of the arm or move the LNB in & out? I have a similar looking multi-LNB rail and the individual LNB holders like to 'walk' along the rail, presumably related to heat cycles.
I monitored the strength ("Quality") of various tx: stronger ones and weaker ones. I noticed that Zagros, 4E, ORTB, RTS, AFN bars were weak or NOT giving an image before 6 pm local. Getting stronger later, even giving a good image at 7.30 local. Signals getting stronger towards midnight.
MY explanation: Satellite 10E is above equator where (on Earth) sun rises 05.20 UTC and sets 17.20 UTC. Satellite is in HOT sunshine during that time, in Earth's shadow 17.20 to 5.20 and cooling off. Exactly the period in which signals get stronger and later disappear again....
Is my explanation right? Then why did I not notice (!) that with any of the 5 other satellites??
Of course the (black....) LNB is ALSO getting hot and later cooling after sunset in parallel with the satellite.....
Does anyone know what is the effect of (low and high) temperature on performance of LNB?
The rail with LNBs is fixed, tilted at about 8°, so simulating the ARC of satellites (28E to 9E). ONLY LNB for 10/9E is adjusted for better reception, but it is ever so critical.....
What is effect of tilting LNB up or down facing the dish? What is effect of twisting LNB sideways (L or R) a bit?
What is the effect of moving LNB towards or away from the dish a bit?
My tests give no clear answers.
What do you mean by "LNBs tend to walk along the rail"?? Please explain, as mine are screwed fixed - of course.
Thank you.
 

ozumo

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When I say the LNB walks along the rail I mean it gradually moves down the slope of the rail over time, it should be OK of you use the screw however mine rusted away.

I have seen the how bright sunlight affects the LNB, which is why I use gutter pipe to shade the LNB:
 

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MY explanation: Satellite 10E is above equator where (on Earth) sun rises 05.20 UTC and sets 17.20 UTC. Satellite is in HOT sunshine during that time, in Earth's shadow 17.20 to 5.20 and cooling off. Exactly the period in which signals get stronger and later disappear again....
Is my explanation right?

No, I definitely don't think so.
The important thing here would not be if the equator itself is in the shadow, but if the satellite is in the shadow of the earth.
As the satellite is rotating about 42.164 km from the center of the earth, I guess the satellite would be in the shadow for max. about 1 hour and 10 minutes per 24 hours, rough calculation; and with seasonal changes (maybe much much shorter in summer- and winter-time?).

So I don't see any relevance in your explanation ATM.

Greetz,
A33

Edit: I changed one word for another: relevance.
 
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brother9

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Several points here: Even the Moon at 400,000 kms (0.5°) takes 1.5 HOURS to traverse Earth's shadow at total lunar eclipse, it is that big. Of course it is irrelevant that Earth's equator is in shadow, but the satellite is over the equator and - for ease of calculation - the moments of sunrise and sunset at equator are taken to be same time the satellite passes into resp. comes out of Earth's shadow at 36000 kms above equator. The Sun (diameter 1,391,000 kms) at 149,500,000 kms throws a beam of Earth's shadow into space, according to my calculations of 89°. The Earth's umbra (dark shadow) is 1,400,000 kms long, at lunar distance 9,500 kms wide. At stationary satellite distance it is MUCH wider.
If your 1h10m is right, then what would be the explanation for signals getting stronger after 6 pm, fading away before 6 am?
 

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When I say the LNB walks along the rail I mean it gradually moves down the slope of the rail over time, it should be OK of you use the screw however mine rusted away.

I have seen the how bright sunlight affects the LNB, which is why I use gutter pipe to shade the LNB:
Did you ever see or record a graph of signal strength during a day+night? Not of BBC1 of course as that always is 99%.
Did your LNB cover help?
 

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Did you ever see or record a graph of signal strength during a day+night? Not of BBC1 of course as that always is 99%.
Did your LNB cover help?
The last time I noticed a definite difference was during the France TV Tour de France feed on 23.5°E last year. I was using a 90cm dish at the time and could not lock a stable picture in the blazing sun. When I placed a shade over the LNB within 20 seconds I got stable video. I have seen similar over the years a few times but usually I have the shade on anyway.

Thinking about it, most of the time I have noticed a difference is with feeds which tend to have lower symbol rate than broadcast transponders - I notice Zagros has a 3800 SR - you have nothing to lose by trying a simple shade but no guarantees it will improve anything.

I have not monitored signal over a day/night period, it is something I will try in the near future.
 

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Of course it is irrelevant that Earth's equator is in shadow, but the satellite is over the equator and - for ease of calculation - the moments of sunrise and sunset at equator are taken to be same time the satellite passes into resp. comes out of Earth's shadow at 36000 kms above equator.

Well, that is a very very rough estimate. :confused
Remember that when the ground has its fist shadow, the sun still lights the clouds above for some time (seemingly from beneath), as they are not in the earth's shadow yet.
This is even much longer for the satellites, that are still further away.

I now calculated more exact:
=DEGREES(ARCSIN(6378/42164)) gives 8.7 degrees, is half the earth's shadow angle for the clarke belt at the equator.
So in total it is 17.4 degrees.
In 24 hours, the satellite rotates 360 degrees.
The 17.4 degrees takes 1 hour and 9,6 minutes.
( I guess several minor factors are not taken into account here.)

But this is only for the shadow pass of the Clarke Belt, when that shadow is exactly in line with sun and earth equator; so in spring and autumn (equinox-time).
As the earth axis is tilted 23.5 degrees, the seasonal effect that I mentioned is even greater than I thought.

Because of the axis tilt, at the longest day in summer, at 'shadow time' the satellite is =42164*SIN(RADIANS(23.5)) = 16813 km above the line sun-earth, so by no means in the shadow of the earth (with polar radius 6357 km).
As we are now near that date, I guess the satellites are sun-lit 24/7 at the moment.


Where your reception fluctuations come from? I don't know. I'll leave that question to others, here.

Greetz,
A33
 

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Well, that is a very very rough estimate. :confused
Remember that when the ground has its fist shadow, the sun still lights the clouds above for some time (seemingly from beneath), as they are not in the earth's shadow yet.
This is even much longer for the satellites, that are still further away.

I now calculated more exact:
=DEGREES(ARCSIN(6378/42164)) gives 8.7 degrees, is half the earth's shadow angle for the clarke belt at the equator.
So in total it is 17.4 degrees.
In 24 hours, the satellite rotates 360 degrees.
The 17.4 degrees takes 1 hour and 9,6 minutes.
( I guess several minor factors are not taken into account here.)

But this is only for the shadow pass of the Clarke Belt, when that shadow is exactly in line with sun and earth equator; so in spring and autumn (equinox-time).
As the earth axis is tilted 23.5 degrees, the seasonal effect that I mentioned is even greater than I thought.

Because of the axis tilt, at the longest day in summer, at 'shadow time' the satellite is =42164*SIN(RADIANS(23.5)) = 16813 km above the line sun-earth, so by no means in the shadow of the earth (with polar radius 6357 km).
As we are now near that date, I guess the satellites are sun-lit 24/7 at the moment.


Where your reception fluctuations come from? I don't know. I'll leave that question to others, here.

Greetz,
A33
Thank you, A33. Good presentation. I did similar calculations earlier: That 1h 9.6m the satellite is in the umbra, more hours in the penumbra (Latin for half-shadow). With the Earth's tilt of 23.5° that umbral cone will indeed be below the satellites on 21 June. They will still be in the penumbra.
IF (if !) this sunshine effect on the satellite signals is true, then it should be easily found in the (online) litterature. I have not found such, And there are too many variables: Frequency, Symbol Rate, signal power, signal direction (footprint), LNB temperature, weather at dish, humidity, ionospheric conditions, etc.
 

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I have been monitoring signal strengths (=quality) on 10A with 9B. I have a (Turkish) tuner only. Signals on ALL 16 stations that I noted were weaker at 17.30 CEST and increased every hour until even 03.10 (or later). Weather is cold (17 -12° night), dry.
Can anyone tell me why? See previous post for a number of variables.
 

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(Continued from "Missing frequencies on Hispasat 30W):
Right. I am still here....
As you can see on this last photo of TRIAX dish, behind it is an oval dish (90x65) aimed at 13° E. LNBs on 28°E, 23°E, 19°E and 13°E give excellent (Quality) signals: up to 99%. AND I have one LNB for Eutelsat 10 and 9. I was watching programs on 6 TER Suisse AND e.g. Kurdistan. BUT:
The 9+10 signals disappeared. Could have been moved during winter storms. I have 2 cables going into the house, 2 Diseqc switches, (and a cable switch in TV room,) changed the LNB, changed the cables to Diseqc box, re-aimed LNB, etc. HOWEVER:
I never get the signals from Eutelsat 10+9 as previously. Station 12BBC2Delay is coded but has 44% signal. ZAGROS has 66% - sometimes. I have been up the ladder 100+ times.... YES, good signal (80%) on Zagros, nothing on 6 TER. Next morning: NO signal at all..... Towards evening: Zagros 45% then 0%, etc.
Can anyone tell me what is up? Have satellites moved? Have their power(s) been reduced? Have their footprints been changed/moved? All my LNBs are black. WHY?? Do they not get VERY hot with (lately....) full June sunshine for 19 hours!?
Remember, I HAD both satellites on ONE LNB in the past.....
Thank you.
It's only me or there is no photo of the dish ?
Maybe my question is stupid but did you just try to test with an other LNB ?
 

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My first message in this thread refers to the photo with Hispasat TRIAX. This is another, oval dish 90x65 aimed primarily at Hotbird 13E, but with 6 LNBs. Yes, I tried another LNB, Diseqc box, short cable, long cable to the TV: all were exchanged.
Last night I monitored signals from 5 pm to 5 am and ALL INCREASED in strength, even to 5 am, to my surprise. I got at least a short signal on most stations Eutelsat9+10: Africa, Swiss, Hungary, Greece AFN stripes,even BBC-World....
So it has to do with temperature? Of the satellite? Atmosphere? My LNBs' temperatures do not change after midnight. Cold night, no rain.
 

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Yes it is temperature related try to cover the lnb
 

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Last night I monitored signals from 5 pm to 5 am and ALL INCREASED in strength, even to 5 am, to my surprise.
Generally ambient temperature keeps falling until sunrise.
 

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Generally ambient temperature keeps falling until sunrise.
Hmmmm...... I am sorry, but I disagree: it is cold and it remains cold, after all, it is "summer" ! NOT more than 3 degrees difference day/night. If temperature, then does a graph of relation temp/signal strength exist? I cannot find one.
Has the D-layer an effect on signal strength ? (Ionosphere). E-layer?
 

brother9

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Yes it is temperature related try to cover the lnb
I covered the LNB with a folded white plastic bag and the 5 other LNBs with a white paper bag - for the moment. Let's see if there is any change in signal strength. Black LNB was surprisingly cold today..... (Wind N, straight from North Sea.)
 

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I covered the LNB with a folded white plastic bag and the 5 other LNBs with a white paper bag - for the moment. Let's see if there is any change in signal strength. Black LNB was surprisingly cold today..... (Wind N, straight from North Sea.)
What was the daytime temperature last few days
 
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