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  1. #1
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    Default Problem in C band transmission


    Last Hope of getting C band channels
    I have a problem in all my c band channels in as i 'm not getting many channels of Insat 2E,Asiasat2,Asiasat3,Intelsat10.Whole thaicom,insat 3c. etc
    As master of this froum adviced me time to time to change my lnb,dish 8 feet solid,cable,i changed all of these and even checked it on different receivers but all in vain.
    Two different dishfitter (having more than ten years experience in this field) told me that there is vibration in c band channels due to telephone,mobile,police,bank towers parallel to my dish antenna .
    As i change whole system now which device may i use to avoid this vibration as i fail to receive popular urdu and indian channels on these satellites.I spend alot of money on new system.
    Plz help
    Last edited by naumaniqbal; 29th July 2007 at 01:29.

  2. #2
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    Default

    if you have done all that in vain,
    now tell the experts to do the job and pay when its thru.

  3. #3
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    OK, lets look at the problems, bit by bit. Firstly the dish is aligned correctly with the satellites, The LNB is correct with the correct frequency 5150, programmed into the receiver. Are you getting any signal indication on the receivers signal strength meters , Both quality and strength. If not then your dish is out of alignment.. If Yes, then have you double checked that the frequency's loaded are correct. I know this all sounds basic, but nine times out of ten, It's something simply that's preventing a picture on the screen. It may also be the "skew" of the LNB is not correct. Try turning the LNB in the scalar ring and see if it improves the signal strength. Is the LNB focal length correct.

    You say you could possible have interference to the signal caused by telephones etc,, that's wrong, as is the so-called vibration. However it could be "Wireless" broadband, that can play havoc with c-band frequencies, due to the fact that it's very close to the c-band frequency, and you get a small amount of overlap in the signal.

    I say all this without even knowing whether you have wireless broadband in your country... There are filters available, which will counteract the interference, or you could construct a "skirt" round the edge of the dish.
    This amounts to a strip of aluminium, about 12 inches high, attached to the perimeter of the dish, To channel the signal, and stop any conflicting signal entering the dish space.

    O you could get your experts back, As Cogil suggested, and make them sort it out. and get them to demonstrate every satellites programs, before they leave. or they get paided.
    regards from OZ bassett

  4. #4
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    Dear bassett
    Hi, can pls advise, can there be any interference in c band frequency if there is a GSM base station nearby your dish....lets say 100m away.... Will the signals of c-band get weaker....
    I am also facing some problems....in getting Ary and Hum tv. The signal strength is 60-70% but signal quality is 20%...Never gets above...
    My equipments are SCI-190M Digitall receiver and 2.10m Offset antenna.... I have a dual band feed with a scalar ring(from my old prime focus dish) on it. The only thing is that.....without scalar ring i cant get the signal and the scalar ring is attached at the end of the throat of feedhorn and the feedhorn is a bit towards the dish..slightly away from the joint of the 3 rods of dish.... should i move the feedhorn away from the dish and connect it on the joint exactly....maybe signals may increase which they call focus of LNB....
    Waiting for your comments......

  5. #5
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    Quote Originally Posted by nasirsyed0 View Post
    Hi, can pls advise, can there be any interference in c band frequency if there is a GSM base station nearby your dish....lets say 100m away.... Will the signals of c-band get weaker....
    GSM won't affect your signals.

  6. #6
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    Thanks to all for immediate help.
    @bassett
    Yes i agree with u that this is not because of GSM as there were many mobile towers for about 4-5 years in my locality.It might be due to another new service which u diagnose .Plz help me by showing the diagram how i can make "ALuminium Skirt" as u mentioned.or any other filter which would work.
    The channels which i am n't getting in which i am interested are
    ASIASAT 3s(zee fta package vibrate sometimes,star utsav too)
    1.TV one
    2.AAJ tv
    3.Ptv Global
    Asisasat 2 all package
    Insat 2E
    All channels except two frequencies
    Thaicom (vibrating signal on some frequencies) NO channel
    Insat 3c (no Signal)
    Panamasat (DD Boquet,Geo,hum,indiatv,dawntv)
    Paksat (all)
    Hope for a Positive and Practical Suggestion.(Thanks in advance to all RDI members)

  7. #7
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    Smile C band

    C-Band Freq are shared with terrestrial micro wave transmission which can cause interference with weaker signals in certain areas so you need a bigger dish ,but C-band have Less path loss, so do you have the Quality and Strenght signal & whats the percentage % ? If you have more than 50% or 70% than its NOT the interferences you are getting around your location,as said by our Experts its not cos of GSM or other radio transmission but as said Broadband can be the problem as C bands are mean to transmit signals further than KU bands.Check on the Stronger signals 1st .
    Quote Originally Posted by naumaniqbal View Post
    Thanks to all for immediate help.
    @bassett
    Yes i agree with u that this is not because of GSM as there were many mobile towers for about 4-5 years in my locality.It might be due to another new service which u diagnose .Plz help me by showing the diagram how i can make "ALuminium Skirt" as u mentioned.or any other filter which would work.
    The channels which i am n't getting in which i am interested are
    ASIASAT 3s(zee fta package vibrate sometimes,star utsav too)
    1.TV one
    2.AAJ tv
    3.Ptv Global
    Asisasat 2 all package
    Insat 2E
    All channels except two frequencies
    Thaicom (vibrating signal on some frequencies) NO channel
    Insat 3c (no Signal)
    Panamasat (DD Boquet,Geo,hum,indiatv,dawntv)
    Paksat (all)
    Hope for a Positive and Practical Suggestion.(Thanks in advance to all RDI members)

  8. #8
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    Quote Originally Posted by nasirsyed0 View Post
    Dear bassett
    Hi, can pls advise, can there be any interference in c band frequency if there is a GSM base station nearby your dish....lets say 100m away.... Will the signals of c-band get weaker....
    I am also facing some problems....in getting Ary and Hum tv. The signal strength is 60-70% but signal quality is 20%...Never gets above...
    My equipments are SCI-190M Digitall receiver and 2.10m Offset antenna.... I have a dual band feed with a scalar ring(from my old prime focus dish) on it. The only thing is that.....without scalar ring i cant get the signal and the scalar ring is attached at the end of the throat of feedhorn and the feedhorn is a bit towards the dish..slightly away from the joint of the 3 rods of dish.... should i move the feedhorn away from the dish and connect it on the joint exactly....maybe signals may increase which they call focus of LNB....
    Waiting for your comments......
    I,v just read your reply, and have the answer for you...
    your using the wrong scalar ring, you need an off-set tapered scaler ring. basicly your using a prime focus LNB set-up on an OFF-set dish. This is why the signal is so weak [[[[[ signal quality is 20% ]]]]

    As for interferance, I would doubt terrestrial micro wave transmissions are the cause, due to the fact I,ve seen c-band dishes and microwave dishes side by side.
    A large amount of RF hum, could cause some disruption, but consider the fact that your signal strength is only 20%, when with that size dish, 80% signal strenth should be the norm.
    regards from OZ bassett

  9. #9
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    Quote Originally Posted by Gregory Carmal View Post
    C-Band Freq are shared with terrestrial micro wave transmission which can cause interference with weaker signals in certain areas so you need a bigger dish ,but C-band have Less path loss, so do you have the Quality and Strenght signal & whats the percentage % ? If you have more than 50% or 70% than its NOT the interferences you are getting around your location,as said by our Experts its not cos of GSM or other radio transmission but as said Broadband can be the problem as C bands are mean to transmit signals further than KU bands.Check on the Stronger signals 1st .
    On our local TV station [PRIME] some of the programming is downloaded via C-band, and next to it is the microwave dish to transmit the signals to the terrestrial transmitter.

    I really think our friends problem is simply the fact that he's using a flat scaler ring on a off-set dish and it's incapable of collecting the required amount of signal. He could possable add a strip of metal sheeting round the outside of the scalar ring, in an attempt to collect more signal. But really he needs a tapered off-set scalar ring, for the thing to work as it should.
    regards from OZ bassett

  10. #10
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    Smile C band Problem

    Yes I think you are right, he have to rectify his scalar ring and confirmed the signal power than we know whats the other problem.Thanks Bassett sir

    Quote Originally Posted by bassett View Post
    On our local TV station [PRIME] some of the programming is downloaded via C-band, and next to it is the microwave dish to transmit the signals to the terrestrial transmitter.

    I really think our friends problem is simply the fact that he's using a flat scaler ring on a off-set dish and it's incapable of collecting the required amount of signal. He could possable add a strip of metal sheeting round the outside of the scalar ring, in an attempt to collect more signal. But really he needs a tapered off-set scalar ring, for the thing to work as it should.

  11. #11
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    Dear friends....thanks for your nice comments and helps....but where can i find a taperd scalar ring....moreover what is tappered? you mean conical? if so ...i am unable to find it here in Turkey.....people dont even know what it is like....another question is.....what is the replacement....i tried a plastic conical flask sometimes ago...but signals didnt even come...obviusly i put this conical flask on the throut of the feed....
    what other things u can recommend....I am getting all channels in perfect signal level like ..............signa strength above 60% and signal quality above 50% but ARY and Hum tv is signal strength above 60% but stable signal quality of 20%...doesnt even increase.....
    There is something wrong i am doing but WHAT
    Waiting for your further comments....
    Thanks in advance......

  12. #12
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    Smile C-Band

    Brother can you post a photo of your dish and the LNB with the present ring,hope we can get some idea from that picture and hope we can help you.Regards
    Quote Originally Posted by nasirsyed0 View Post
    Dear friends....thanks for your nice comments and helps....but where can i find a taperd scalar ring....moreover what is tappered? you mean conical? if so ...i am unable to find it here in Turkey.....people dont even know what it is like....another question is.....what is the replacement....i tried a plastic conical flask sometimes ago...but signals didnt even come...obviusly i put this conical flask on the throut of the feed....
    what other things u can recommend....I am getting all channels in perfect signal level like ..............signa strength above 60% and signal quality above 50% but ARY and Hum tv is signal strength above 60% but stable signal quality of 20%...doesnt even increase.....
    There is something wrong i am doing but WHAT
    Waiting for your further comments....
    Thanks in advance......

  13. #13
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    Quote Originally Posted by Gregory Carmal View Post
    Brother can you post a photo of your dish and the LNB with the present ring,hope we can get some idea from that picture and hope we can help you.Regards
    He's told you, he's using a standard prime focus scalar ring, with a standard C-band LNB. The problem is the scaler ring does not conform with the structure of the dish. It would be exactly the same as using a Ku off-set LNB on a prime focus dish, your only going to get a persentage of the signal
    regards from OZ bassett

  14. #14
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    on c band there's nothing you can do about inteference with other signals, that's very much succeptible unlike ku! you can minimized it only by relocation but you can't completely avoid it!

    there are places in my location(near microwave towers, pots repeaters etc) that one can't even get a picture at all!
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  15. #15
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    Dear bassett
    You seem to be the only sensible person to answer my questions at the moment...but please rest do not mind....I have checked many forums and dicussions saying that i need to replace my scalar ring. It says that the difference between offset and prime focus scalar rings is that in prime focus it is staright in shape but in offset it is conical in shape....but my problem now is that where do i purchase this....i have some spare prime focus rings...can i add metal rings and bring it to a conical shape...wil this work....
    waiting for your advice or places to buy this .....
    rgds

 

 

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