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AT9 dish

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by Stevies3, May 19, 2013.

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  1. Stevies3

    Stevies3 Legend

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    Ditto, I never retweaked & rock solid signals. I guess having the braces for exrra support is important.
     
  2. machavez00

    machavez00 Hall Of Fame

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    yep, SL3
     
  3. CCarncross

    CCarncross Hall Of Fame

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    I still have my original AT9 with braces in place that was installed in Oct 2006.....high 90's and a few 100's across all relevant transponders, never been adjusted since original install.
     
  4. Stevies3

    Stevies3 Legend

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    Just curious, are the coordinates the same with an AT9 and AU9 slimline setup?
     
  5. P Smith

    P Smith Mr. FixAnything

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    coordinates are relevant to you position, for dish setup we use angles: tilt/skew, azimuth ans elevation (latest are the same for AT-9 or AU-9 with 5 LNBFs)
     
  6. peds48

    peds48 Genius.

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    My dish is rock solid as well. However, when Sandy came to say hello (I live a few miles from the coast and as such was hit hard), my signals dropped enough to not be able to pass IV. Instead of re-peaking my 3 year old dish, I put a new one… :D Why? because I can… :righton:
     
  7. TomCat

    TomCat Broadcast Engineer

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    I have no idea how true this is, but I was told the SLs are significantly hotter than the AT/AUs. If so, that would imply that the LNBFs are the reason why, since the SL has a smaller reflector. I think any time you get an opportunity to go to a newer dish with newer LNBFs, you should take it unless it is going to cost you, because slow dropoffs in power are a classic method of LNBF failure over time.

    Tuned properly, you should be able to get 100 on your local spot beams, assuming you are relatively in the center of that. It may get only 96-97 if you are further out in the footprint, and of course nothing usable if you are outside the footprint.

    I think I must agree that 100s on CONUS sats is rare.

    But what we are not sure of is whether the index is the same from DVR to DVR. What indexes to 100 on one DVR model may index to 96 on a different model even if the actual reading is identical. We do not have a real handle on what the true RF level is without a BirdDog or some other pro gear, and we do not know how tight the tolerances are or what DTV assumes to be acceptable from its DVR vendors. I thik it was DTV that was using 125 as the top index for a while, which was really confusing. Maybe it was DISH.

    100 may not even represent the peak, which is one of the reasons why dithering is important. If you can read 100 for a number of screw turns that means that your metering topped out but the peak is still higher and hidden from you, and the only way to find that peak is to find the place where the signal drops on either side, and split the difference.
     
  8. carl6

    carl6 Moderator Staff Member DBSTalk Club

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    The "signal level" reading you see on a receiver or DVR is actually an indication of bit error rate, and not of rf signal. There is no reliable way to correlate the two. It has been demonstrated many times that the same dish, same LNB, same coax, everything the same all the way to the receiver, can give you different readings on different receivers.
     
  9. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    Incorrect again.

    Like on the Beach in Florida. Plenty of 35+ MPH substained winds - and several tropical storms since installation.
     
  10. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    yes
     
  11. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    Agree 100%. And as you are aware the signal will bounce a little given time. In fact, as the birds go around their essentially small figure 8 patterns to save fuel, you can get more variation on the signal.

    That's why I have actually taken my units to other's house and measured the signal off their newly installed Slimlines to make sure that the receiver factor was taken out of it - and I measure mine and theirs within the same hour to make sure the bird is essentially in the same place that day.

    I suspect that one of the things I have going for me is that I happened to install on a day when the birds at the center of the figure 8 and not out on one of the extremes.
     
  12. P Smith

    P Smith Mr. FixAnything

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    Actually it is SNR transforming by some algo. Not a BER.
     
  13. slice1900

    slice1900 Well-Known Member

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    Could you post your readings for 99c and 103ca/103cb? I'm kinda curious to see them.

    I'm pretty sure you would get a bit better signal the further south you are, since the signal passes through less atmosphere at 25* N than at 45* N. I would think (but I'm not sure) that you should do a bit better the closer you are to 101 west longitude, kind of like when you get better readings in the center of a spot beam than at its edge. So I would have thought someone hitting 100s on the HD sats would be deep in the heart of Texas, rather than on a beach in Florida.

    Do your higher readings give you any noticeable benefits? Do you experience any less rain fade than your neighbors? I'm sure you still get it with a big storm, but are there some marginal storms where they experience rain fade and you don't? Or maybe they experience a 10 minute outage and yours is only 5 minutes?

    If you've gone to the trouble of bringing your receivers to neighbors houses and vice versa to compare readings, I imagine you've compared notes on how many minutes of outage you had when you were recording the same thing during a storm :)
     
  14. peds48

    peds48 Genius.

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    did not know that 35+ miles winds was considered a major storm. When I was hit by Sandy, it was 80+ mile wind. Now that is a MAJOR storm.
     
  15. HoTat2

    HoTat2 Hall Of Fame

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    But doesn't BER vary in inverse correspondence to SNR for digital communication systems, so that a 0-100 relative scale based on either parameter would inversely follow the other one in a 1:1 ratio?
     
  16. P Smith

    P Smith Mr. FixAnything

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    I don't see any traces of BER influence to the algo (perhaps a table) what just taking SNR reading from sat tuner and convert it to 0-100 scale.
    Not sure (I have no evidence) if BER is reading/providing to FW at all. As to correspondence, well, it would be correlation below certain level of SNR, but after the level BER is zero, so you can't use it instead.
    My confidence is based on reading system logs in opposite your, guys, post's pure theoretical exercises. :)
     
  17. slice1900

    slice1900 Well-Known Member

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    If BER is zero, increases in SNR beyond that don't really matter. Hypothetically, they could use BER for their signal strength numbers with BER=0 showing as '100' and as the level of BER increases the numbers drop lower until you get to '0', which would the place where BER is so high nothing can be done ("searching for signal") When you have very low signal strengths, like 10 or 20, it does sort of try to form and display a picture. It isn't watchable, but there's enough there to at least try.

    That said, I seem to recall reading a claim someone figured out Directv's algorithm, and SNR of 13 or so was '100', and any increases above that still showed as '100'. Anyone who has a meter that shows SNR could presumably move a dish around with a receiver and meter connected to it at the same time and see how changes in SNR affects the receiver's signal strength readings and see if there is a nice linear correlation between SNR and signal strength. If so, it is highly likely it is based on SNR, since I doubt SNR and BER follow the exact same linear path.
     
  18. HoTat2

    HoTat2 Hall Of Fame

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    Yes that was my understanding as well that at the point of around a 13 db C/N ratio (SNR) at the dish feed horn input corresponded to a relative reading of "100" on the receiver's S.S. meters and at a C/N "threshold" of perhaps 9.5 to 10 db would correspond to about "0" on the meters.

    But between those two extremes I thought it was essentially an inverse linear relationship between C/N (SNR) and BER. Perhaps I was wrong though ... :)
     
  19. P Smith

    P Smith Mr. FixAnything

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    It could be myself; yes I did post a couple of pairs ... as I said, the info [ SS=f(SNR) ] came from receiver's log so I have no doubts at all.
     
  20. slice1900

    slice1900 Well-Known Member

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    The receiver's log? How do you access that?
     
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