Weaker OTA signal in HR10-250 compared to tuner in TV?

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by wozman57, Jan 14, 2006.

  1. wozman57

    wozman57 New Member

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    Nov 20, 2005

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    Just got my HR10-250 today. I noticed on 2 of my 5 local HD OTA channels when "decoded" by the Tivo box, the signal is to low to retain a constant signal (actually, it goes back and forth from 80+ signal strength, back to 10, then back to 80+ ... seemingly randomly on both OTA tuners). On my new HD sony 50' LCD projection (which has it's own HDTV tuner), all 5 local channels come in great.

    Has anybody else experienced this? Via process of elimination, I have ruled out a bad connection.

    Would it be advised that I get an antenna high gain signal amplifier?
     
  2. A J Ricaud

    A J Ricaud Active Member

    1,177
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    Jun 25, 2002
    Hacienda...
    Your description is classic of "multipath distortion" (i.e. signals from more than 1 direction) which interferes with the signal. HD Tivos are notorious for this problem. Do a search for multipath in this forum for info. and recommendations.
     
  3. TyroneShoes

    TyroneShoes HD evangelist

    3,604
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    Sep 6, 2004
    True. It can also be indicative of threshold reception, which could indeed be helped by an amp. While the amp helping is a bit less likely, it is easier to try than dicking with or replacing an antenna. Add the amp and see if the readings improve. If not, or if they go down, you can rule out it being level-related. If they go up, that's progress, and you're set up better to make further improvements to the antenna if necessary. As you may have discovered, the tuner in the Sony is much more tolerant of marginal signals than the tuner in the HR10. The good news is that the tuner in the HR10 replacement is better than either of them, so many of our marginal reception issues may just vanish at swapout.

    I am assuming you have the A10 or SXRD. It should have the same diagnostics as the 60XS955. Not only does it have a signal quality reading similar to the Tivo, it also has a S/N reading. Those two readings together are much more helpful than SQ by itself. You need a minimum of a +15 S/N. I have found that at +19 I was still having occasional dropouts on some channels. Raising that to +26 made a world of difference (added an amp and FM trap, did not touch the antenna).

    If you have variable gain (or can simulate that with a variable attenuator placed after the amp) you can peak for the perfect signal level (there is a point of diminishing returns). You may need to do this for each channel to get an idea exactly what you are dealing with, but the best approach is to do it just for the worst offender, and only modify that setting if if causes degradation to another channel or channels.
     
  4. wozman57

    wozman57 New Member

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    Nov 20, 2005
    I have positioned my antenna to get the best all around reception for the major network stations.

    Here are the diagnostics from my sony TV (not SRX version) on the OTA channels:

    Channel Network Sig Strength SNR
    3.1 CBS 95 30
    9.1 ABC 98 32
    18.1 FOX 98 31
    26.1 NBC 95 30

    All 4 of these channels come in perfectly when decoded from my TV ... but when decoded by the Tivo, the signal strength on two of the stations won't hold as described above. Should I be experiencing this with this diagnostic information? (wich from what I've read on this board, is pretty good). Is it possible that there is someting wrong with the tuner in my tivo?

    I tried a signal amplifier with an FM trap, and the only thing it did was lower the AGC % on every channel (which by the way, I'm not sure if that's good of bad as I don't know what gamma correction is).
     
  5. emarnik

    emarnik New Member

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    Sep 14, 2003

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    I am having the exact same problem, I called up cust svc. and they sent me a new unit. Of course that didn't solve the problem. Sometime I get good reception on the tivo ota hd channels but 90% of the time it's choppy and unviewable. But on my Samsung DLP 61' which has a tuner I get ALL of the HD channels. I'm about to search on multipath like suggested above.

    You are not alone
     
  6. A J Ricaud

    A J Ricaud Active Member

    1,177
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    Jun 25, 2002
    Hacienda...
    wozman57

    The signal strength on those channels are quite high. Good for most receivers, including your TV, apparently, but may be overloading the HD Tivo's tuners. Try a Radio Shack variable attenuator on the HD Tivo's OTA feed, adjust it down, and see if it helps. It is quite inexpensive, so no great loss if it doesn't help.
     
  7. wozman57

    wozman57 New Member

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    Nov 20, 2005
    I'll try the attenuator this evening (hopefully) and see what I get.

    The following is just some more diagnostic information (just in case it might help and at a minimun, just add it to the "archive")...

    Network Orientation Miles Frequency

    3.1 239 24.2 23
    9.1 169 22.9 34
    18.1 170 22.4 27
    36.1 235 24.2 22

    I have a radio shack 80" 32-Element Antenna (model VU-90 XR) assembled in my attic (2 story house). I live in Mooresville NC (28117) ... which is about 20 miles north of Charlotte. I have my antenna pointed due south at 180 degrees (which through trial and error appears to be the best placement for all around channel reception).

    Too bad FOX and CBS don't have the same orientation (the 2 locals that I care most about) ... cause I'd be willing to point the antenna directly at these stations and "sacrafice" the other two, just so that I could Tivo some of my favorite programming in HD...
     
  8. cardpetree

    cardpetree New Member

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    Jan 12, 2006
    Louisville, KY
  9. CoryTV

    CoryTV New Member

    90
    0
    Apr 25, 2002
    Norfolk
    This may be premature, but I have serious OTA signal issues with my HDTivo, too.. My antenna is a silver sensor (wired up to the second floor office) and I get about 90 signal strength without multipath fluctuations. (I gather the silver sensor is reasonably directional-- it's sorta yagi-shaped) However, during some broadcasts, the dropouts are unbearable. Not only do the number of dropouts make the wife pissed, but the WAIT after a dropout is terrible.. Rarely does it miss much data, but it stutters terribly, and just seems to "lose it's mind" for up to 10 seconds before continuing, having missed only like 1 second of actual program data...

    I've ordered a channel master 4221 to see if that helps at all. My #s for the "big 4" are all near 90 with almost no fluctuation, so this is a bit confusing.. No buildings near me, and I have it on the second floor, so it shouldn't have any multipath issues at all!

    Does the HDTivo's OTA tunner just plain suck?

    Cory
     
  10. A J Ricaud

    A J Ricaud Active Member

    1,177
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    Jun 25, 2002
    Hacienda...
    Are you sure this is happening only with OTA? It almost sounds like a hard drive going bad.
     
  11. jcricket

    jcricket New Member

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    Sep 11, 2002
    Seattle, WA
    A) This sounds more like a hard drive going bad (unless it only happens on the OTA channels.
    B) Yes, the OTA tuner sucks on the HR10-250. Others with standalone HD tuners (either the H10 or a built-in ATSC tuner) based on the more recent "chip sets" have a lot better luck with any marginal signals. Given you statement about "90" (which is very high for signal quality) it makes me suspicious that you're having some other kind of problem (not unheard of).
     
  12. wozman57

    wozman57 New Member

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    Nov 20, 2005
    Variable attenuator failed. My next attempted option is to switch to two directional antennas (one pointed and 170 and the other at 237), but first, I'm going to figure out how to set such a thing up...
     
  13. generalpatton71

    generalpatton71 Open,Flash and clear

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    Oct 30, 2002
    Classified
    Yeah this is a multipath issue. I have one of if not the best antenna out there in the ch 4228. My signals come from the SE,S and SW. If I point directly south I can pick up all channels in the 90s, but then the SE and SW signals start to jump back and forth like crazy.Sometimes I can find a sweet spot that lats until a windy day comes along and then it takes a week or so using my rotor to find that sweet spot again. My Zenith set that has a built in tuner does not suffer from this problem though. I look forward to the series 3 to get my ATSC signals more reliably.
     
  14. CoryTV

    CoryTV New Member

    90
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    Apr 25, 2002
    Norfolk
    Yeah, It's bizarre. Definitely OTA only.. it's a reception issue, not a playback issue.. When it happens it happens A LOT. Keep in mind, I have never actually been able to switch over from a program having major problems to check the signal at that time.

    Now, I am near a naval base, so it's very possible that it's related. AWACS planes fly around, so that could be screwing with UHF... Hell, maybe the aircraft carriers are in my line of sight, and sometimes their blocking the way like big buildings would... That would explain the random behavior... Maybe I have a "moving multipath" issue.. :)

    Some shows seem especially vulnerable. Desperate housewives (9pm et Sundays ABC) was especially bad.. Alias (9 pm thursdays ABC) also had problems fairly consistently.. Lost, (9pm wed. ABC) is usually just fine...

    Before this weeks episode of desperate housewives, I super fine tuned the antenna specifically for my ABC affiliate, got it up to 92, and that seems to have helped. I'm pretty sure there were no issues at all during this episode.

    Now, this is not limited to ABC, or I would start to wonder about the affiliate. I have problems on my CBS affiliate as well-- same thing, some times it's perfect, other times it's like dense cloud cover on satellite-- unwatchable.

    Again, hopefully the CM4221 will help. I'm within 13 miles of the transmitters and they are all within a 3 degree range, so hopefully this will work itself out...


    Cory
     
  15. CoryTV

    CoryTV New Member

    90
    0
    Apr 25, 2002
    Norfolk
    Actually, I may have figured it out.

    [​IMG]

    Getting "great" signal, with no apparent multipath made me wonder.. maybe something IS getting between me & the towers intermittently. Here's a pic of my (estimated) LOS to the towers-- it shows 2 major things-- 1) direct path of landing/taking off aircraft from the base (I believe the AWACS take off there, although we dont get major traffic "touch and gos" like other bases...)

    That wouldn't explain the sheer volume of issues.. but futher down, there's a place where ships are loaded/unloaded in the Norfolk terminals.. A huge cargo ship could literally come into port and block my line of sight-- is a 10-14 story building 3 miles away enough to give multipath issues?

    It would explain, however, why a show can seem to be going fine and then all of a sudden, it becomes unwatchable-- a ship comes in?

    Hmm...
     
  16. JTAnderson

    JTAnderson Active Member

    940
    76
    Jun 6, 2000
    Redondo...
    The first thing you need to do then is to Google "jointenna".
     
  17. wozman57

    wozman57 New Member

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    Nov 20, 2005
  18. poppagene

    poppagene User

    796
    1
    Dec 29, 2001
    I had a similar problem. The tuners on my Hughes HTL-HD, voom box, LG LST-3510A and the Directv H20 all got more channels with better strength than the HR10-250. I asked for an in warranty replacement and the advanced replacement unit they sent me had even worse reception for over the air. I finally opened up the box and wondereed if the problem might be where the ota signal comes into the HR10-250 or in the interior cabling that runs from the back panel connection to the 2 tuners inside the unit. I tried hooking up the OTA antenna leads directly to the ATSC tuners inside the box and all my reception problems were eliminated. I tried replacing the cables from the back panel to the ATSC tuners without success so my conclusion is that the problem for me was occurring when the HR10-250 split the OTA signal to the 2 ATSC tuners. Now I just feed the signal into the box directly by running a cables through a vent hole and directly connecting to the ATSC tuners.
     

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