Help Required Poor reception on one frequency

[BarryC]

I am experiencing poor reception for channels on 11306 H and V which mostly comprises of the full range of Channel 5 and Great TV! channels.

On a clear sunny day the C5 channels will stutter a lot and the Great! channels will most likely go to no signal. In this situation signal strength is about 90% and quality will be erratic ranging from 0-40%.

However, on a bad weather day with cloud and heavy rain, the signal on these channels actually improves with the channels becoming stable and watchable with signal quality reaching 50-60%.

All my other UK spot beam channels are being received at 90% strength, 100% quality without any issues.

I've had the dish moved, the alignment professionally checked twice, LNB replaced and a new cable run but the issue remains. The last guy said external interference was to blame and nothing more could be done. I don't have a DECT phone and my router is the other side of the house. Also, I have a very limited area to place the dish so moving it again isn't an option.

If anyone could suggest any further solutions or options I could try I'd much appreciate it. Thanks for reading!

 

[ozumo]

Which Freesat box are you using? Do you live close to a mobile phone tower? Improvement when raining could be caused by an attenuation of interference or an indication the LNB or receiver is suffering in the heat.

If the box is a Freesat 4K unit you could try a different LNB type, they work with wideband (Sky Q type) LNBs as well as legacy universal LNBs. Wideband LNB coverts 11306MHz to 896MHz (11306 minus 10410) before sending it to the receiver, universal LNB sends 1556MHz (11306 minus 9750). This would help if interference is close to the frequencies being sent to the receiver.

If the receiver's tuner is being overloaded by a 'loud' LNB a simple attenuator would help but I'd expect more frequencies to be affected if that was the case. It may still be worth trying if nothing else helps.

 

[Channel Hopper]

Can you try the receiver on another dish nearby ?

 

[Terryl]

Some questions (for now) what satellite is this on, how low to the horizon is it at your location and whats out in front of your satellite dish?

 

[Analoguesat]

Is the LNB skew (twist) set correctly - it may be its set wrong & the opposite polarities are interferening with each other.

 

[BarryC]

Which Freesat box are you using? Do you live close to a mobile phone tower? Improvement when raining could be caused by an attenuation of interference or an indication the LNB or receiver is suffering in the heat.

If the box is a Freesat 4K unit you could try a different LNB type

I'm about 650 metres away from a phone mast which is clearly visible from the dish. It definitely seems like the rain dampens the interference - I forgot to mention that now it is winter and the leaves are off the trees the reception is noticeably worse than it was in summer so if the problem is interference the added foliage helped reduce it.

This problem originally appeared when I was using an old Humax HDR-1000s with a quad LNB but I have since moved to a 4K Freesat box with a new hybrid LNB and the problem remains.

Can you try the receiver on another dish nearby ?

Possibly - I'm in a semi-rural area and we are all spread out over a lumpy peninsula. However, my nearest neighbour only has terrestrial.

Some questions (for now) what satellite is this on, how low to the horizon is it at your location and whats out in front of your satellite dish?

Astra 2F. The dish elevation is 19.6°. About 30 metres away is a thin line of trees but they should be low enough for line of site clearance assuming DishPointer and the app on my phone are correct.

Is the LNB skew (twist) set correctly - it may be its set wrong & the opposite polarities are interferening with each other.

I did mention this to one of the installers to double check so hopefully it is set correctly. Are there any other channels I could test that would be more vunerable to an inaccurate skew?

 

[ozumo]

This problem originally appeared when I was using an old Humax HDR-1000s with a quad LNB but I have since moved to a 4K Freesat box with a new hybrid LNB and the problem remains.

Are you using the wideband or universal outputs of the hybrid LNB? If you can record 3 or more channels simultaneously then you are using the wideband outputs.

Are there any other channels I could test that would be more vunerable to an inaccurate skew?

Try 11344:

 

[BarryC]

Are you using the wideband or universal outputs of the hybrid LNB? If you can record 3 or more channels simultaneously then you are using the wideband outputs.


Try 11344:

View attachment 153478

Yes I have the 4K box connected to the wideband output. I have the old Humax box connected to the legacy ports and the reception issues are replicated on this box also.

Checking those channels all are coming in at 90% strength 100% quality.

 

[ozumo]

If it is external interference, affecting both receivers would point to it being around 11306MHz rather than the down-converted frequencies sent by the LNB. If you have an SDR it may be possible to find where the interference is coming from and where the dish can be located where it is shadowed from it - for example the rear of the house rather than the front.

 

[Channel Hopper]

I did mention this to one of the installers to double check so hopefully it is set correctly. Are there any other channels I could test that would be more vunerable to an inaccurate skew?

If you can take a - good - picture of the dish from the front, somebody should be able to confirm if the skew is wildly out.

 

[Terryl]

I'm about 650 metres away from a phone mast which is clearly visible from the dish. It definitely seems like the rain dampens the interference - I forgot to mention that now it is winter and the leaves are off the trees the reception is noticeably worse than it was in summer so if the problem is interference the added foliage helped reduce it.

This problem originally appeared when I was using an old Humax HDR-1000s with a quad LNB but I have since moved to a 4K Freesat box with a new hybrid LNB and the problem remains.


Possibly - I'm in a semi-rural area and we are all spread out over a lumpy peninsula. However, my nearest neighbour only has terrestrial.


Astra 2F. The dish elevation is 19.6°. About 30 metres away is a thin line of trees but they should be low enough for line of site clearance assuming DishPointer and the app on my phone are correct.


I did mention this to one of the installers to double check so hopefully it is set correctly. Are there any other channels I could test that would be more vunerable to an inaccurate skew?

This possible problem (in bold type) could be that the signals from this satellite are bouncing off something in the path to the satellite, I have seen this many times when the satellite is at just the correct angle to the object causing the signal to bounce, this bounced signal is 180 degrees out of phase from the main signal and will cause a drop in the overall signal. (or in some cases a total drop out)

I would take a look on google earth and see whats out in front of you, a large metal roof on an industrial building, a large body of water, a large open field, a large car park or even something that radio mast could be the problem.

To see if this may be the cause a little trigonometry would be needed, you know the elevation of the satellite, then you would need to see whats in the path to the satellite that may be causing the signal bounce, it doesn't have to be a direct in-line object as your not getting a full fade out in the signal, it could be something off to one side.

 

[Channel Hopper]

This possible problem (in bold type) could be that the signals from this satellite are bouncing off something in the path to the satellite, I have seen this many times when the satellite is at just the correct angle to the object causing the signal to bounce, this bounced signal is 180 degrees out of phase from the main signal and will cause a drop in the overall signal. (or in some cases a total drop out)

I would take a look on google earth and see whats out in front of you, a large metal roof on an industrial building, a large body of water, a large open field, a large car park or even something that radio mast could be the problem.

To see if this may be the cause a little trigonometry would be needed, you know the elevation of the satellite, then you would need to see whats in the path to the satellite that may be causing the signal bounce, it doesn't have to be a direct in-line object as your not getting a full fade out in the signal, it could be something off to one side.

Heavy rain on flat ground.

 

[BarryC]

If it is external interference, affecting both receivers would point to it being around 11306MHz rather than the down-converted frequencies sent by the LNB. If you have an SDR it may be possible to find where the interference is coming from and where the dish can be located where it is shadowed from it - for example the rear of the house rather than the front.

Unfortunately I don't have an SDR. I only have one wall where the dish can be located so my options are limited - it might be a case of having to tolerate this issue. If only C5 hadn't changed frequency - I could live without the Great! channels.

If you can take a - good - picture of the dish from the front, somebody should be able to confirm if the skew is wildly out.

The dish is too high for me to get a decent picture at the moment.

This possible problem (in bold type) could be that the signals from this satellite are bouncing off something in the path to the satellite, I have seen this many times when the satellite is at just the correct angle to the object causing the signal to bounce, this bounced signal is 180 degrees out of phase from the main signal and will cause a drop in the overall signal. (or in some cases a total drop out)

I would take a look on google earth and see whats out in front of you, a large metal roof on an industrial building, a large body of water, a large open field, a large car park or even something that radio mast could be the problem.

To see if this may be the cause a little trigonometry would be needed, you know the elevation of the satellite, then you would need to see whats in the path to the satellite that may be causing the signal bounce, it doesn't have to be a direct in-line object as your not getting a full fade out in the signal, it could be something off to one side.

That is interesting to know. Looking in the direction that my dish points there are two open fields in the 100-300 metres range of the signal path. There doesn't appear to be any metal roofed buildings. Funnily enough looking at DishPointer there is another phone mast 2.5Km away that is right in the line of the signal but this could be a bit far. The phone mast that is 650m away from me and clearly visible from the dish would be positioned at roughly 90° to the arm so its signal path would cut across my satellite signal.

 

[Terryl]

One thing it could be is an RF spur on some piece of equipment on that radio mast that is 2.5 Km away from you, or the one closer to you, RF signals are funny, if you have a transmitter with a small problem it could cause what is called a spur, (spurious emission) in some cases this spur could be quit high in RF amplitude, this spur could be higher or lower in frequency from the main signal, if you know the channel frequency your having problems with and the LO frequency of the LNB your using, (look at Ozumo's second sentence in his first post) you could get an idea on what RF signal could be the problem.

Another possible problem could be what is called a harmonic, this is two or more RF frequency's mixing together (unintentionally) to produce another unwanted frequency, (or more) these problems would be caused by poor equipment maintenance of the RF equipment.

The only way to really see whats going on is to use an RF spectrum analyzer and sweep the RF band, however this type of equipment is very expensive and is not readily available to a consumer.

As only one channel is being affected I would suspect it's something close by, and at a strong enough level to get into the LNB it's self, it would have to at just the correct angle to get into the eye of the LNB, or at the correct angle to get a bounce off the dish into the LNB, if it's bouncing off the dish then it has to be to the left or right of the LNB.


Sorry got long winded due to to much coffee.

 

[Channel Hopper]

Another possible problem could be what is called a harmonic, this is two or more RF frequency's mixing together (unintentionally) to produce another unwanted frequency, (or more) these problems would be caused by poor equipment maintenance of the RF equipment.

Having a hybrid LNB should hopefully eliminate the issue (unless everything is in the same metal casing and cheap components are bouncing stuff everywhere)

Did the last one on site think to change the LNB just in case ?

 

[BarryC]

As only one channel is being affected I would suspect it's something close by, and at a strong enough level to get into the LNB it's self, it would have to at just the correct angle to get into the eye of the LNB, or at the correct angle to get a bounce off the dish into the LNB, if it's bouncing off the dish then it has to be to the left or right of the LNB.

The nearest phone mast is located roughly 50° north east from the dish so any signal would be coming in from the right side as you look at the dish so that could be a possibility.

Having a hybrid LNB should hopefully eliminate the issue (unless everything is in the same metal casing and cheap components are bouncing stuff everywhere)

Did the last one on site think to change the LNB just in case ?

I'm on my third LNB since the channel loss. It started with an old quad which was upgraded to a hybrid, then a 2nd hybrid replaced that. Although I'm not sure any would have been considered faulty as it has only been this one frequency that has been an issue.

Just trying to think of any other possibilities, my closest neighbour who lives the same side as the dish, about 20m away, has a Fritzbox. I believe that Fritzboxes are routers that also have built in DECT. Checking the WiFi signal it wouldn't be that strong, not sure the range of the DECT though.

Also, can anyone recommend any DIY options to insulate the dish from external interference?

 

[Channel Hopper]

The nearest phone mast is located roughly 50° north east from the dish so any signal would be coming in from the right side as you look at the dish so that could be a possibility.


I'm on my third LNB since the channel loss. It started with an old quad which was upgraded to a hybrid, then a 2nd hybrid replaced that. Although I'm not sure any would have been considered faulty as it has only been this one frequency that has been an issue.

Just trying to think of any other possibilities, my closest neighbour who lives the same side as the dish, about 20m away, has a Fritzbox. I believe that Fritzboxes are routers that also have built in DECT. Checking the WiFi signal it wouldn't be that strong, not sure the range of the DECT though.

Also, can anyone recommend any DIY options to insulate the dish from external interference?

DIY at Ku band is really a case of putting the dish elsewhere unless you can build a brick wall either side with just a narrow aperture facing the satellite.

Have you tried attenuating the signals by adding a 10/20m run of cable, just in case there is too much coming in at that frequency ?
It might be the case if you have a Zone 2 dish or larger (you didn't take any pictures and your profile doesn't help).

 

[dmaavrigdo]

Do you have a meter in the coax? Once knew someone missing one channel. I suggested he remove the meter and Voila!

 

[Terryl]

One other thing..Is the coax going down to the receiver properly grounded??? I have seen direct outside RF leakage getting into the coax, this was caused by a poor ground, the shield on the coax does several things, one is to provide a return path for the DC voltage out to the LNB, a shield to prevent outside interference from getting into the signals coming down from the LNB and a shield to stop signals from affecting outside equipment from the signals coming down from the LNB.

The signals coming down from the LNB are down converted from the 11.5 to 12.6 GHz signals from the satellite by a internal Local Oscillator, these signals are coming down all at once, (once down converted by the LO) so every channel on that satellite are available at the internal tuner inside the receiver, it is the tuner that decides what channel you looking at once you decide on the channel you want to look at.

This is a very complicated mess of frequency's getting down and into the receivers tuner, so if some unwanted signal was getting into the coax at some point you would have a even bigger mess.

It could be a bad "F" connector at some point, a bad ground block or a crusty connection from the ground block to the ground point it's self, so another question is how old is the coax going out to the dish?

 

[a33]

I am experiencing poor reception for channels on 11306 H and V

Have you, in case of a drifted LOF, tried frequency 11303?
And frequency 11309?

(Or you could change the LOF values, for testing ~ same effect.)

Greetz,
A33