Had the strangest fault today, customer complaining of pixelation,
checked BER could not get a "quality" reading on my Horizon meter,
changed LNB for known good one, still no reading, dish was a bit
small, so changed for a bigger model, but could only get between 0 and
20% quality reading, where I would normally expect 90-98% from the
same configuration. Ran out of time, so went back today, moving the
dish as I thought it might be too close to a wall in front, still the
same. Then I noticed that I was getting a Signal strength reading,
even when the dish was not pointing at a satellite, and not pointing
at any other object, where usually I would expect a near  Zero
strength reading. I then noticed (this is on the 10th floor) that
there where a cluster of mobile phone antenna's, on an adjacent
building close by, two of which were pointing at the back of my 1.35
Metre dish, they were about 20 Metres away (I wondered why I was
feeling warm). I have never encountered this problem before, what do
people think, is it likely that these Antennas are paying havoc with
my BER, I do not posess a Spectrum Analyser, so cannot tell who is
interefering with my signal. If it is these antenna's, is there
anything I can do about it (apart from the obvious)?

Spectrum Analyser is on my shopping list, but the one I want is over
2K, so will come, but not soon.

>  If it is these antenna's, is there
> anything I can do about it (apart from the obvious)?

There is a procedure for reporting interference with radio
and television services, not sure if it covers satellite.
Did once have a problem with police messages
breaking through (pre Tetra), local churches had
similar problems with public address breakthrough.
Police weren't happy with being evesdropped on,
it got sort of fixed.
Try
http://www.ofcom.org.uk/radiocomms/ifi/glines/interference/interference/
they say their assistance does not cover analogue
satellite TV, but of course this is digital.

On Wed, 18 Jun 2008 19:17:41 +0200, Anti-Spam  wrote:

> is it likely that these Antennas are paying havoc with
> my BER, I do not posess a Spectrum Analyser, so cannot tell who is
> interefering with my signal. If it is these antenna's, is there
> anything I can do about it (apart from the obvious)?

It is possible both that the mobile phone signals are interfering, but that
does not prove they are faulty or blameworthy.  If they are injecting
strong signals at say 1,800MHz, used primarily by Orange and T-Mobile, into
your downlead those signals will be inside the band used to carry signals
through your downlead from the LNB to the satellite receiver.

If that is the cause of your problems then using better screened coax
and/or adding an attenuator ahead of your receiver may help.

> Spectrum Analyser is on my shopping list, but the one I want is over
> 2K, so will come, but not soon.

A good quality spectrum analyser would be a useful tool to diagnose your
problem.  Maybe you can borrow or hire one instead of having to buy it.

Tony

That reminds me, I was going to post this picture of
the TV interference on all analogue channels in my
hotel room (Premier Inn Dundee West) a couple of
weeks ago:
http://myweb.tiscali.co.uk/infoweb/rfi.jpg

The view from out of the window may well have
been the cause:
http://myweb.tiscali.co.uk/infoweb/cassegrain.jpg

-- 
Graham

%Profound_observation%

"Graham."  wrote in message 
news:g3btol$ehl$1@registered.motzarella.org...
> That reminds me, I was going to post this picture of
> the TV interference on all analogue channels in my
> hotel room (Premier Inn Dundee West) a couple of
> weeks ago:
> http://myweb.tiscali.co.uk/infoweb/rfi.jpg
>
> The view from out of the window may well have
> been the cause:
> http://myweb.tiscali.co.uk/infoweb/cassegrain.jpg
>
> -- 
> Graham
>
> %Profound_observation%
>


Why would a sophisticated receive dish cause a problem? Might even be 
where your TV picture was coming from!


-- 
Woody

harrogate three at ntlworld dot com

On Thu, 19 Jun 2008 08:32:57 +0100, "Woody"
 wrote:

>"Graham."  wrote in message 
>news:g3btol$ehl$1@registered.motzarella.org...
>> That reminds me, I was going to post this picture of
>> the TV interference on all analogue channels in my
>> hotel room (Premier Inn Dundee West) a couple of
>> weeks ago:
>> http://myweb.tiscali.co.uk/infoweb/rfi.jpg
>>
>> The view from out of the window may well have
>> been the cause:
>> http://myweb.tiscali.co.uk/infoweb/cassegrain.jpg
>>
>> -- 
>> Graham
>>
>> %Profound_observation%
>>
>
>
>Why would a sophisticated receive dish cause a problem? Might even be 
>where your TV picture was coming from!

The picture is not clear, but I think that it has an uplink
transmitter fitted.

"Anti-Spam"  wrote in message 
news:4a3k54h9k84di4n3icmt061atdhbfs99hd@4ax.com...
> On Thu, 19 Jun 2008 08:32:57 +0100, "Woody"
>  wrote:
>
>>"Graham."  wrote in message
>>news:g3btol$ehl$1@registered.motzarella.org...
>>> That reminds me, I was going to post this picture of
>>> the TV interference on all analogue channels in my
>>> hotel room (Premier Inn Dundee West) a couple of
>>> weeks ago:
>>> http://myweb.tiscali.co.uk/infoweb/rfi.jpg
>>>
>>> The view from out of the window may well have
>>> been the cause:
>>> http://myweb.tiscali.co.uk/infoweb/cassegrain.jpg
>>>
>>> -- 
>>> Graham
>>>
>>> %Profound_observation%
>>>
>>
>>
>>Why would a sophisticated receive dish cause a problem? Might even be
>>where your TV picture was coming from!
>
> The picture is not clear, but I think that it has an uplink
> transmitter fitted.

Yes the window was dirty and could not be opened.
The device looking at the secondary dish is
almost as long as the arm, has cooling fins, and
is clearly more than an LNB, but I agree you can't
see it too well. What is it used for I wonder? the site
is a Premier Lodge/Beefeater Pub (Whitbread Group PLC)
I would have thought their data needs could be met by
an ADSL line.
-- 
Graham

%Profound_observation%

On Thu, 19 Jun 2008 09:12:29 +0100, "Graham."  wrote:

>
>
>"Anti-Spam"  wrote in message 
>news:4a3k54h9k84di4n3icmt061atdhbfs99hd@4ax.com...
>> On Thu, 19 Jun 2008 08:32:57 +0100, "Woody"
>>  wrote:
>>
>>>"Graham."  wrote in message
>>>news:g3btol$ehl$1@registered.motzarella.org...
>>>> That reminds me, I was going to post this picture of
>>>> the TV interference on all analogue channels in my
>>>> hotel room (Premier Inn Dundee West) a couple of
>>>> weeks ago:
>>>> http://myweb.tiscali.co.uk/infoweb/rfi.jpg
>>>>
>>>> The view from out of the window may well have
>>>> been the cause:
>>>> http://myweb.tiscali.co.uk/infoweb/cassegrain.jpg
>>>>
>>>> -- 
>>>> Graham
>>>>
>>>> %Profound_observation%
>>>>
>>>
>>>
>>>Why would a sophisticated receive dish cause a problem? Might even be
>>>where your TV picture was coming from!
>>
>> The picture is not clear, but I think that it has an uplink
>> transmitter fitted.
>
>Yes the window was dirty and could not be opened.
>The device looking at the secondary dish is
>almost as long as the arm, has cooling fins, and
>is clearly more than an LNB, but I agree you can't
>see it too well. What is it used for I wonder? the site
>is a Premier Lodge/Beefeater Pub (Whitbread Group PLC)
>I would have thought their data needs could be met by
>an ADSL line.

There is a Pay Per View sex channel operating out of room 381, they
need it for their uplink. Knock on their door and ask them to turn it
off for a moment, see if that cures the problem.

"Anti-Spam"  wrote in message 
news:pufi54tklp5i2qoosjqbodlk9rh4aij7tr@4ax.com...
> Had the strangest fault today, customer complaining of pixelation,
> checked BER could not get a "quality" reading on my Horizon meter,
> changed LNB for known good one, still no reading, dish was a bit
> small, so changed for a bigger model, but could only get between 0 and
> 20% quality reading, where I would normally expect 90-98% from the
> same configuration. Ran out of time, so went back today, moving the
> dish as I thought it might be too close to a wall in front, still the
> same. Then I noticed that I was getting a Signal strength reading,
> even when the dish was not pointing at a satellite, and not pointing
> at any other object, where usually I would expect a near  Zero
> strength reading. I then noticed (this is on the 10th floor) that
> there where a cluster of mobile phone antenna's, on an adjacent
> building close by, two of which were pointing at the back of my 1.35
> Metre dish, they were about 20 Metres away (I wondered why I was
> feeling warm). I have never encountered this problem before, what do
> people think, is it likely that these Antennas are paying havoc with
> my BER, I do not posess a Spectrum Analyser, so cannot tell who is
> interefering with my signal. If it is these antenna's, is there
> anything I can do about it (apart from the obvious)?
>
> Spectrum Analyser is on my shopping list, but the one I want is over
> 2K, so will come, but not soon.

"Anti-Spam"  wrote in message 
news:...

> Had the strangest fault today, customer complaining of pixelation,

> checked BER could not get a "quality" reading on my Horizon meter,

> changed LNB for known good one, still no reading, dish was a bit

> small, so changed for a bigger model, but could only get between 0 and

> 20% quality reading, where I would normally expect 90-98% from the

> same configuration. Ran out of time, so went back today, moving the

> dish as I thought it might be too close to a wall in front, still the

> same. Then I noticed that I was getting a Signal strength reading,

> even when the dish was not pointing at a satellite, and not pointing

> at any other object, where usually I would expect a near Zero

> strength reading. I then noticed (this is on the 10th floor) that

> there where a cluster of mobile phone antenna's, on an adjacent

> building close by, two of which were pointing at the back of my 1.35

> Metre dish, they were about 20 Metres away (I wondered why I was

> feeling warm). I have never encountered this problem before, what do

> people think, is it likely that these Antennas are paying havoc with

> my BER, I do not posess a Spectrum Analyser, so cannot tell who is

> interefering with my signal. If it is these antenna's, is there

> anything I can do about it (apart from the obvious)?

>

> Spectrum Analyser is on my shopping list, but the one I want is over

> 2K, so will come, but not soon.

You really do need an analyser.

Two basic interference mechanisms:

1. Sat downlink frequencies. Holding an LNB in the air without a dish and 
moving it round will find the source, then you can resite the dish or erect 
a screen.

2. Sat IF frequencies. Often gets into the receiver directly, or via scarts 
or aerial loop, so disconnect latter and also observe if moving receiver 
about, etc, affects fault. In extremis put the receiver in a room away from 
the source of interference.

This sort of thing can be a bugger in high rise flats.

Bill

On Sun, 22 Jun 2008 02:57:17 +0100, "Bill Wright"
 wrote:

>
>"Anti-Spam"  wrote in message 
>news:pufi54tklp5i2qoosjqbodlk9rh4aij7tr@4ax.com...
>> Had the strangest fault today, customer complaining of pixelation,
>> checked BER could not get a "quality" reading on my Horizon meter,
>> changed LNB for known good one, still no reading, dish was a bit
>> small, so changed for a bigger model, but could only get between 0 and
>> 20% quality reading, where I would normally expect 90-98% from the
>> same configuration. Ran out of time, so went back today, moving the
>> dish as I thought it might be too close to a wall in front, still the
>> same. Then I noticed that I was getting a Signal strength reading,
>> even when the dish was not pointing at a satellite, and not pointing
>> at any other object, where usually I would expect a near  Zero
>> strength reading. I then noticed (this is on the 10th floor) that
>> there where a cluster of mobile phone antenna's, on an adjacent
>> building close by, two of which were pointing at the back of my 1.35
>> Metre dish, they were about 20 Metres away (I wondered why I was
>> feeling warm). I have never encountered this problem before, what do
>> people think, is it likely that these Antennas are paying havoc with
>> my BER, I do not posess a Spectrum Analyser, so cannot tell who is
>> interefering with my signal. If it is these antenna's, is there
>> anything I can do about it (apart from the obvious)?
>>
>> Spectrum Analyser is on my shopping list, but the one I want is over
>> 2K, so will come, but not soon.
>
>"Anti-Spam"  wrote in message 
>news:...
>
>> Had the strangest fault today, customer complaining of pixelation,
>
>> checked BER could not get a "quality" reading on my Horizon meter,
>
>> changed LNB for known good one, still no reading, dish was a bit
>
>> small, so changed for a bigger model, but could only get between 0 and
>
>> 20% quality reading, where I would normally expect 90-98% from the
>
>> same configuration. Ran out of time, so went back today, moving the
>
>> dish as I thought it might be too close to a wall in front, still the
>
>> same. Then I noticed that I was getting a Signal strength reading,
>
>> even when the dish was not pointing at a satellite, and not pointing
>
>> at any other object, where usually I would expect a near Zero
>
>> strength reading. I then noticed (this is on the 10th floor) that
>
>> there where a cluster of mobile phone antenna's, on an adjacent
>
>> building close by, two of which were pointing at the back of my 1.35
>
>> Metre dish, they were about 20 Metres away (I wondered why I was
>
>> feeling warm). I have never encountered this problem before, what do
>
>> people think, is it likely that these Antennas are paying havoc with
>
>> my BER, I do not posess a Spectrum Analyser, so cannot tell who is
>
>> interefering with my signal. If it is these antenna's, is there
>
>> anything I can do about it (apart from the obvious)?
>
>>
>
>> Spectrum Analyser is on my shopping list, but the one I want is over
>
>> 2K, so will come, but not soon.
>
>You really do need an analyser.
>
>Two basic interference mechanisms:
>
>1. Sat downlink frequencies. Holding an LNB in the air without a dish and 
>moving it round will find the source, then you can resite the dish or erect 
>a screen.
>
>2. Sat IF frequencies. Often gets into the receiver directly, or via scarts 
>or aerial loop, so disconnect latter and also observe if moving receiver 
>about, etc, affects fault. In extremis put the receiver in a room away from 
>the source of interference.
>
>This sort of thing can be a bugger in high rise flats.
>
>Bill
>
I am pretty sure it was the first, because the problem was at the dish
end, before being fed into the downlead. The original dish I was
replacing to improve reception quality, was sitting behind a low wall.
The bigger dish I was fitting, could not help but pop its head above
the top of this wall. That was when we started hitting problems, we
could not get a decent BER. Thought it was because we were a bit too
close to some overhead power lines, so resited the dish away from the
power lines, but because of the topography, meant the dish was now
sitting even higher above the top of the wall, our BER was even worse.
We resited the dish once again before realising what the problem might
be.

There was just no place to fit the dish behind a wall, away from the
telephone mast, and could not start building up the original wall, to
form a screen, the residents comittee would all have had babies.

Spent some 7 hours on this job over two visits. ended up refitting the
original dish, no charge to the customer of course, although she did
give us a very nice bottle of wine for our trouble. Lesson learnt.

"Anti-Spam"  wrote in message 
news:fnjs54dvh2sd0tug96lcv7qtpkamb2b8e6@4ax.com...
> On Sun, 22 Jun 2008 02:57:17 +0100, "Bill Wright"
>  wrote:
> There was just no place to fit the dish behind a wall, away from the
> telephone mast, and could not start building up the original wall, to
> form a screen, the residents comittee would all have had babies.
>
> Spent some 7 hours on this job over two visits. ended up refitting the
> original dish, no charge to the customer of course, although she did
> give us a very nice bottle of wine for our trouble. Lesson learnt.

As I said, use an LNB without a dish to find the interference direction. You 
could prob do this with a meter only, tuned to the frequency of a badly 
affected mux, set to signal strength (not BER etc). Having done this (or 
not) use a large metal sheet to experiment with dish screening. Actually you 
will usually find that the interference gets in looking over the shoulder of 
the dish, straight into the LNB. The best stuff for making a screen is the 
mesh used to form a base for car body filler. The brand name is 'David'.

Sometimes the interference bounces off a building and that puts it in line 
to get straight into the LNB. A metal screen just beyond the dish edge can 
be very effective. Looks funny though! In theory a big dish with an LNB with 
the wrong f/d ratio should work.

Bill