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OTA channels & signal strengths

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by Bob Coxner, Jun 15, 2007.

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  1. Bob Coxner

    Bob Coxner Icon

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    Basically, my HR20 OTA reception is fine. I get all channels that I should get and their signal strengths appear to be accurate. The ones that never pixelate are near 100% and the problem child is in the 40% range - as expected.

    I do have one anomaly that I'm wondering if anyone can shed some light on. My 40% channel (channel 44.1) actually works very well most of the time. I'm using unamped rabbit ears and it's about 20 miles from me, no hills or obstructions. The curious one is that I get a signal strength of 85% consistently (both tuners) on a channel 8.1 that is 80 miles from me. The curious part is that despite the consistent 85% signal strength, all I ever get is "searching for signal" when I try to tune to it in the guide.

    How can get an excellent picture from a 40% signal and absolutely nothing from an 85% signal? I seem to recall reading that the HR20 signal strength meter isn't incredibly accurate but my readings on roughly 25 local channels seem to be consistent with my experiences while watching. It's only the one channel where the reading is wildly different from what I'm (not) seeing.

    Any ideas?
     
  2. davring

    davring Hall Of Fame

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    Must be an anomaly because you shouldn't even get a signal at all at that distance with rabbit ears. Don't know what would cause the indicated signal.
     
  3. Bob Coxner

    Bob Coxner Icon

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    Dec 28, 2005
    I must have good rabbit ears. :) It's not consistent, and usually only in the evenings/overnights but I do often get KERA 13.1 from Dallas. That's 80.3 miles according to antennaweb. I've been able to get decent 13 analog on various tvs (again, only evenings/nights) over the years with just rabbit ears. 13.1 is at 8 degrees and 80.3 miles from me. It's PBS. 8.1 WFAA is at 7 degrees and 80.4 miles. It's ABC. I haven't researched it but I assume their output powers should be similar. I don't get any signal strength for any other Dallas channels.

    As Alice in Wonderland would say, it's curiousier and couriouser.
     
  4. John4924

    John4924 Icon

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    Mar 19, 2007
    Do a query at the attached FCC website

    http://www.fcc.gov/mb/audio/tvq.html

    You can filter the data to suit your situation. You will find each station's power rating, tower location, service area, etc.

    Hope this helps. I would recommend you get a fairly inexpensive VHF/UHF antenna installed in your attic? and ditch the rabbit ears! :)

    Cheers,
    John
     
  5. Bob Coxner

    Bob Coxner Icon

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    Dec 28, 2005
    Thanks for the link. Actually, I'm not that desperate to get Dallas OTA since it would just duplicate my local ABC. I was more curious about the apparent anomalous signal strength readings. Could it be bleed over signal being read?: The strange readings are for distant channel 8.1 and I do have a strong local signal for channel 9.1.
     
  6. davring

    davring Hall Of Fame

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    Jan 13, 2007
    I know that many RF frequencies are effected by "skip". I am not an expert but I was always under the impression that only affected lower frequencies, AM radio for instance. I could see it happening to VHF but I would be surprised to see it with UHF. But weather conditions can create many strange signal deflections. Maybe someone here has more accurate information.
     
  7. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    While 8.1 & 9.1 seem next to each other, in the RF spectrum, they may be many channels apart, as they are mapped to show 8.1 & 9.1 from channels that could be 34 & 65.
    The FCC works hard so the channels don't "bleed over". There is a member that needed to use three FM traps to knock down a local transmitter that was "swamping" the OTA tuner though.
     
  8. Bob Coxner

    Bob Coxner Icon

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    Weather definitely affects tv skip. For me, at least. :) Today was a perfect example. I almost never get 13.1 during the daytime, using rabbit ears. This is the 80 mile away channel. There was a heavy cloud cover this morning and 13.1 was coming in perfectly. The clouds have now gone away and so has the 13.1 signal.

    In the olden days I was a shortwave radio listener. As I recall, skip was always best at dusk and dawn. Nights were good, days were bad. I don't know how relevant that is to UHF skip but I do know that I generally only get 13.1 when it's dark outside.
     
  9. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I'd guess air density has more to do with it.
    "Rabbit Ears" for 80 miles?
    You could definitely use a "real" antenna [with some gain].
     
  10. texasbrit

    texasbrit Well-Known Member

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    Aug 9, 2006

    IN DFW channel 8 WFAA is 8.1 digital and broadcasts on channel 9. It's the only DFW channel that is on VHF right now. But KCEN-DT NBC 9.1 is in Temple TX and transmits on channel 9 also, and that's much closer to the OP than the DFW station (my guess is the OP is in Waco or thereabouts). So either the station the OP is receiving is actually KCEN, or the antenna is pointed at WFAA but there is so much signal coming in the back of the antenna from KCEN that the receiver can't sort out the confused signal it is getting.
     
  11. Bob Coxner

    Bob Coxner Icon

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    Yeah, I'm a bit south of Waco. Your scenario seems to make the most sense of any I've seen so far. However, if I'm actually receiving KCENDT then shouldn't I be getting that picture on 8.1 rather than searching for signal? The signal strength on 8.1 is consistently in the 80% range, which is actually much better than I get on 9.1 KCENDT. KCEN usually is around 45-50%. These numbers are what have had me confused from the start. 80% and I get searching for signal. 45% and I get a perfect picture. :)
     
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