whiteoaks7
Well-Known Member
Yes folks, down here in port Napoleon the excellent astra 28E signal gets worse after sunset - this is contrary to what I was taught about signal propogation so anyone have an explanation?
Satellite tv decays after dark
- Thread starter whiteoaks7
- Start date
ccscott49
Well-Known Member
How big is your dish? May need a larger one.
zefender
Well-Known Member
We've a house in the Pyrenees and have the same problem. It certainly is worse in the evening but this may be (in our case) because it tends to cloud over towards the end of the day. uk-satellite-tv.co.uk offers the following explanation(s)..
" I live outside the UK and lose my satellite signal in the evening around 9pm. Why does this happen?"
In certain parts of Europe the Astra satellite signal (usually Astra 2D & the North beam) is extremely weak and the signal is marginal at the best of times, even with a large dish. In the evening, the strength of the satellite signal generally weakens. If the signal strength during the day is low, then by evening it may well drop below the threshold required by the digibox.
The only way to prevent this from happening is as follows:
Install a bigger dish
Use a low threshold receiver such as the Pace 2600C1
Use a low noise LNB, such as the Invacom Quad
We do not know for sure why the signal drops in the evening. 'What Satellite' magazine suggested the following:
"The geostationary orbit of the satellite is not actually stationary - for various reasons the satellite does drift; it is equipped with a propulsion system to correct these movements. While these movements in the orbit may well have some effect on reception at the fringes of the footprint, we believe that this is not significant and that the major effect on evening reception is caused by the loss of solar power at night, when the satellite switches over to battery power"
Nick Kett recently wrote in and commented:
"I think 'What Satellite' mag has still not nailed the problem...
A satellite only has around 60 "nights" per year ranging from a few mins to several hours each... it's not an every night thing... so we can ignore that one..
Thermal noise .... maybe, but that should be much worse during the day and better at night.
Ionosphere...very little effect on KU band and would be worse some days and almost nothing on others..
Satellite dropping power because another transponder has been turned on is one maybe...
Broadcast satellites maintain downlink power by using an ALC (Automat Level Control) and have a dB or two in reserve for each transponder... new satellites could have even more available power, but the downlink is maintained at the calculated "end of life" figure to allow for solar panel and other degradation.
So I suspect the output from the satellite is a constant.
I think the most likely cause is Satellite pointing accuracy. Geo satellites are kept in position by burning precious fuel....when the fuel is all gone the satellite has reached the end of it's life. All geo satellites move around, if you use a 3m+ dish for KU then it needs constant tracking. Satellites are pulled by the gravitational pull of the sun and the moon. On a day to day basis they trace a figure of 8 in the sky, mainly north to south movement. The station keeping is about 0.25deg, any better than that and the bird has to burn a lot more fuel and would have a shorter operational life..
As the satellite pitches up and down the pointing of the satellite antenna changes, so the footprint moves up and down a little on the earth. In the beam centre and near the beam edge, it's not too much of a problem, but footprints do not just fade away the further you are away from beam center, outside the main lobe, there are deep nulls and further little peaks... It's the movement of these "nulls" that is most likely causing the losses of signal in southern Europe at night".
...hope this helps!
" I live outside the UK and lose my satellite signal in the evening around 9pm. Why does this happen?"
In certain parts of Europe the Astra satellite signal (usually Astra 2D & the North beam) is extremely weak and the signal is marginal at the best of times, even with a large dish. In the evening, the strength of the satellite signal generally weakens. If the signal strength during the day is low, then by evening it may well drop below the threshold required by the digibox.
The only way to prevent this from happening is as follows:
Install a bigger dish
Use a low threshold receiver such as the Pace 2600C1
Use a low noise LNB, such as the Invacom Quad
We do not know for sure why the signal drops in the evening. 'What Satellite' magazine suggested the following:
"The geostationary orbit of the satellite is not actually stationary - for various reasons the satellite does drift; it is equipped with a propulsion system to correct these movements. While these movements in the orbit may well have some effect on reception at the fringes of the footprint, we believe that this is not significant and that the major effect on evening reception is caused by the loss of solar power at night, when the satellite switches over to battery power"
Nick Kett recently wrote in and commented:
"I think 'What Satellite' mag has still not nailed the problem...
A satellite only has around 60 "nights" per year ranging from a few mins to several hours each... it's not an every night thing... so we can ignore that one..
Thermal noise .... maybe, but that should be much worse during the day and better at night.
Ionosphere...very little effect on KU band and would be worse some days and almost nothing on others..
Satellite dropping power because another transponder has been turned on is one maybe...
Broadcast satellites maintain downlink power by using an ALC (Automat Level Control) and have a dB or two in reserve for each transponder... new satellites could have even more available power, but the downlink is maintained at the calculated "end of life" figure to allow for solar panel and other degradation.
So I suspect the output from the satellite is a constant.
I think the most likely cause is Satellite pointing accuracy. Geo satellites are kept in position by burning precious fuel....when the fuel is all gone the satellite has reached the end of it's life. All geo satellites move around, if you use a 3m+ dish for KU then it needs constant tracking. Satellites are pulled by the gravitational pull of the sun and the moon. On a day to day basis they trace a figure of 8 in the sky, mainly north to south movement. The station keeping is about 0.25deg, any better than that and the bird has to burn a lot more fuel and would have a shorter operational life..
As the satellite pitches up and down the pointing of the satellite antenna changes, so the footprint moves up and down a little on the earth. In the beam centre and near the beam edge, it's not too much of a problem, but footprints do not just fade away the further you are away from beam center, outside the main lobe, there are deep nulls and further little peaks... It's the movement of these "nulls" that is most likely causing the losses of signal in southern Europe at night".
...hope this helps!