Over-the-Air Digital Reception Issues and Discussion

Discussion in 'Local Reception' started by Stuart Sweet, Jun 14, 2009.

  1. Jul 18, 2009 #41 of 151
    Jim5506

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    We need your location (TVFool report), antenna, coax run lengths and any pre-amps you are running?

    What is the RF channel of FOX 2?
     
  2. Jul 18, 2009 #42 of 151
    rlgold88

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    here is the info fromtv fools
    [​IMG] Not sure if the above link is going to work but this is the tvfool report.
    Fox 2 Transmitter Profile Detail
    WJBK-DT (Digital)
    Channel: 7 (2.1)
    Network: Fox
    Maximum ERP: 27.200 kW
    Coordinates: 42.460591 -83.213817

    NOTE: The vertical dimensions in this profile have been exaggerated in order to make the terrain features more visible. This is merely an approximation based on the information available from the FCC database.


    Effective ERP: 25.182 kW (Adjusted according to your location)
    Distance: 7.8 miles Azimuth: 213 degrees Compass: 220 degrees

    Distance from antenna to ground block 30-35 ft est
    from ground block to 4 way splitter 10 ft
    the outs from the 4 way are from 10 smallest length to 50 largest length

    On the equipment I get fox 2 in they show a reception sterength of 95-100 but receive no signal on other equipment weird.
    Thanks for the help
    Rob report from tv fools try this one http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=74fa802d74c729
     
  3. Jul 18, 2009 #43 of 151
    Jim5506

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    Try swapping some connections, move the Hr20-100 to the connection on the 4 way splitter that goes to the HDTV.

    You might also swap the receivers around, move the Hr20-100 that gets no signal to the connection where the other Hr20-100 does get signal.

    The results of these little experiments might give us some clue of what is happening.
     
  4. Jul 18, 2009 #44 of 151
    harsh

    harsh Beware the Attack Basset

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    You have split the signal far too many times before it gets to the TV and converter. It isn't how many outlets you create but a decided cutting down of the signal with each splitter.

    The first splitter leaves you with about 20% of the antenna signal on each leg. The 3-way leaves you with 5% of the signal and the 2-way nets you about 2% of what the antenna is putting out. Putting in more splitters multiplies the reduction in signal as opposed to being additive. 20% (4-way) X 25% (3-way) X 40% (2-way) = 2% (remaining signal a round-number WAG based on insertion loss and other inefficiencies).

    As a test, you could try coupling in a cable directly from the antenna to the devices that don't seem to be working and see if it is indeed signal loss that is the problem. At your distance, there may also be some multipath issues or problems with your cabling network acting like an antenna (creating other multipath issues)

    The failure on the DIRECTV equipment is a discussion for a DIRECTV forum as there are other issues involved with being able to receive a channel or not. There you could check the signal using the DTV converter.
     
  5. Jul 18, 2009 #45 of 151
    Tower Guy

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    FM interference.
     
  6. Jul 18, 2009 #46 of 151
    rlgold88

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    Thanks guys
    I tried one of the converter box to a direct line from the 4 way splitter. where the tv is connected TV gets Fox 2 100 percent reception
    after connecting the converter box to tv I still did not get Fox 2 2-1 in (no signal) but all other channels 100 percent reception.
    I reconnected ant cable to TV and fox2 is back on 100 % reception along with all the other locals.

    I understand that for each splitter I will lose db all the splitters are of decent quility and cable and connections are excellent quility. I have great reception on all channels except for Fox2 from the equipment that dont see that signal. The equipment that see the Fox 2 signal show 100 pecent.



    I just dont know why only that one channel is a problem.
    I guesse my next step is to take out all splitteres and go directly to the equipment that dont get the reception on fox 2 and see if that works? Or do you suggest something else?
    Thanks Rob
     
  7. Jul 18, 2009 #47 of 151
    SayWhat?

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    I'd try cable straight from the antenna to each of the problem devices even if it means laying it out across the floor temporarily.

    Avoid conventional splitters. Use powered distribution amps in your case. They can split the signal with no loss, maybe even some gain.
     
  8. Jul 18, 2009 #48 of 151
    rlgold88

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    I went directly from antenna (by passing all splitters) to the compnents that dont get fox 2. They still had an issue.
    So I put splitters back and just for the heck of it I decided to reset channel search on the converter and HDTV box and for some reason that was the trick because I get Fox 2 in with 100% Now I have reset numerous times and it didnt work but this time it worked????
    Next I reset the HR-20 and I now get 2-1 but the sub 2-2 gets (searching for signal).

    Now what is strange is I have reset those numerous times this time it worked.

    I guesse some of the boxes are finikie.

    Thanks for the help
    Rob
     
  9. Jul 19, 2009 #49 of 151
    nnnn3950

    nnnn3950 New Member

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    before the dtv switch I received all the over the air channels on my dtv converter box. 3.1, 5.1, 7.1, 8.1, 10.1, 12.1, 15.1, 45.1. 61.1

    After that the analog signal went out so did half the stations. 8.1, 10.1, 12.1 and recently 5.1.

    I read about digital ready antennas being the problem. but it still doesn't explain why I lost those station and had them before.

    Any ideas?
     
  10. Jul 19, 2009 #50 of 151
    CCarncross

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    Do you have a strictly UHF antenna or a VHF/UHF model? Did any of your stations change to VHF? YOu might want to check at antennaweb.org or tvfool to see what changed.
     
  11. Jul 20, 2009 #51 of 151
    n3ntj

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    I've given up on getting WPVI 6.1 from Philly. I've tried several VHF antennas, including 2 that I built tuned specifically for 85 MHz. One has approx. 6.2 dB gain and I get no PSIP info about 70 miles west of Philly. WPVI raised their power to 30 kW and still no go. Not sure if the power increase has helped the large majority of people closer to Philly that still couldn't get the WPVI signal. I think the only chance I still have is if WPVI decided to go back to UHF. The Philly UHF stations are much stronger here (with a UHF antenna, of course).
     
  12. Jul 20, 2009 #52 of 151
    nnnn3950

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    I have a VHF/UHF antenna. I live 80 miles from the stations towers. But on antennaweb.org it says I only get channels 7.1. I get more then what they say. I contacted FCC to try to find out what was going on they said I should be thankful for what i have. But like I said I got those channels perfectly fine before they turned off analog and again those are DTV Channels and not analog channels. That's what puzzles me.

    What about there reception strength?:confused:
     
  13. Jul 20, 2009 #53 of 151
    n3ntj

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    When did Antennaweb.org change from listing the stations you may get to only showing the very local stations? I am near Phily, Baltimore, and DC and can get many of these stations OTA, in addition to those in my market (Harrisburg/Lancaster, PA). Now when I use antennaweb.org, however, only the Harrisburg stations show up on their list.
     
  14. Jul 20, 2009 #54 of 151
    CCarncross

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    Most likely what has happened is they are operating at a much lower power than they were b4 the analog cutoff...Several of my stations are actually operating at lower power than b4 they cutoff the analog signal...
     
  15. Aug 18, 2009 #55 of 151
    ChrisPC

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    D* finally updated their channel mapping for Nashville. They added the new ThisTV subchannel on 5.3.
     
  16. Sep 8, 2009 #56 of 151
    Jerry Springer

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    The way that the FCC designed the power limitations of the new DTV is that the reception range is about 60 miles.

    In the analog days there were two effectively transmitters for the TV
    station.

    A transmitter for the video and a transmitter for the audio.
    The video transmitter was Amplitude Modulation see
    http://en.wikipedia.org/wiki/NTSC

    The audio was FM at a much lower power.

    The reason that the video was a higher power is that AM is more susceptible
    to noise requiring a stronger signal at the receive and a higher power
    output of the video transmitter

    http://en.wikipedia.org/wiki/Television_station
    "In North America, full-power stations on band I (channels 2 to 6) are
    generally limited to 100 kW analog video (VSB) and 10 kW analog audio (FM),
    or 20 kW digital (8VSB) ERP. Stations on band III (channels 7 to 13) can go
    up by 5dB(W) to 316 kW video, 31.6 kW audio, or 63.2 kW digital. Low-VHF
    stations are often subject to long-distance reception just as with FM.
    There are no stations on channel 1.

    UHF, by comparison, has a much shorter wavelength, and thus requires a
    shorter antenna, but also higher power. North American stations can go up
    to 5000 kW ERP for video and 500 kW audio, or 1000 kW digital. Low channels travel further than high ones at the same power, but UHF does not suffer from as much electromagnetic interference and background "noise" as VHF, making it much more desirable for TV.

    Despite this, in the U.S., the FCC is took another large portion of this band (channels 52 to 69) away, in contrast to the rest of the world, which has been taking VHF instead.

    This means that some stations left on VHF will be harder to receive after the analog shutdown".



    UHF communications are more "line of sight" communications than lower
    frequency VHF.
    It is sort a like having a sound vs a light.
    If you make sound it radiates in all directions, around buildings, through walls, down into holes (valley).

    Shining a light does not go around corners or through walls and if it is a
    pinpoint light it doesn't go down into the valleys.

    The earth is round and eventually the beam of light, UHF TV the beam will
    no longer touch the earth but go up into the sky.

    Here is some information concerning line of sight and how it effects TV
    http://www.softwright.com/faq/support/earth_curvature_values.html

    http://www.ian-ko.com/ET_Surface/UserGuide/ETS_LOS_Discussion.htm

    http://en.wikipedia.org/wiki/Horizon

    The height of the transmitting antenna is factored into the power output of
    the TV station.
    The power output for TV & FM is rated in ERP (Effective Radiated Power)
    There are a number of factors the go into this calculation.
    Several Key items are:
    Height of Antenna. listed both as HAAT (Height Above Average Terrain) and
    AMSL (Height Above Mean Sea Level)

    Gain of antenna: Just like your receiving antenna has gain in db so does
    the transmitter.
    Remember 3db gain is equivalent to doubling the output power. or 1/2 the
    electric consumption expense.

    Silly people who live around Philadelphia and watched analog television and does not understand how digital television works will always be disgruntled and wonder why I cannot receive this station anymore.

    The power of the digital station is lower than the analog because the digital is going to take up more available channels - some for the real station and some for the translators and the FCC took away a large part of the useable bands for reception.

    The goal is to have as many channels as possible in as small a space as possible.

    With all the cell phones and pagers and WIFI, police, fire, news something had to give up some of it's bandwidth to allow more space for the other mobile communications. So you gained some telephone service and you lost some television service. That's all well and good for important people who HAS to have cell phone, but does nothing for a person like me - who doesn't give a damn if all the cell phones in the world stopped working today!

    I cringe everytime I see a young person walking around with a cell phone to their ear, like they are someone important. The world is full of idiots.
     
  17. Sep 8, 2009 #57 of 151
    Jerry Springer

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    Here is a calculator for Friis Transmission Equation

    http://www.random-science-tools.com/electronics/friis.htm

    Enter in transmit power, transmit antenna gain, receiver antenna gain, received power, range, frequency and wavelength and it will tell you how much power you can expect to receive at your location.

    The numbers on the edge of the report - which is generated by your address and antenna height on the TV Fool report is a generalized estimation of how much power you can expect to receive at your location.

    Once you get past -80 nm (db) - you can pretty much forget it!

    http://www.tvfool.com/index.php?option=com_wrapper&Itemid=90
     
  18. Sep 27, 2009 #58 of 151
    n3ntj

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    Is anyone in the Philly market having problems receiving WYBE (35.x) using an HR20-700? I can receive it at 80%+ on my tv's tuner but only get 771 message (no signal) on the HR20. The other Philly stations I can get on the tv tuner, I can get on the HR20-700.

    I wonder if the HR20-700 isn't mapping WYBE correctly. This has been going on for months.
     
  19. Oct 30, 2009 #59 of 151
    BernieL

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    I am in the Atlanta Area and use an OTA antenna as well as subscribe to Dish Network locals. In Atlanta, the guide shows almost exclusively the main channel, e.g., XX.1. The other subchannnels just say DTV service. A friend in Panama City, Florida gets almost all the subchannel information on the Dish Guide in his area. Does anyone know why Dish does not show subchannels in a major city like Atlanta, but does so for a smaller city in Florida?
     
  20. Nov 22, 2009 #60 of 151
    Jerry Springer

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    Everyone in the Philly market is having problems with the DTV transition.

    If you go up the page and read what I posted, you will see how the signal is transmitted.

    A polite way to explain why you are having problems is due to the fact that WPVI is on real channel 6. The power level is 30.20 Kw

    WZPA is even worse on channel 2 with a .045 Kw.

    WHYY is on channel 12 - at 20 Kw

    For the most part, all the other stations is on UHF.

    If you lived in downtown Philly, you would have about 45 gettable stations, if you had a antenna that was a large antenna that was higher then everything else around you. For the most part, there is no co channel interference. But there is enough adjacent channels that multipath plays havoc with your signals.

    Anytime you have a building that is more then 3 stories high between you and the signal, you will have problems trying to receive the signal.

    Yes the power level is down from the analog signal, but it does not take as much power to transmit as far with digital as it did with analog. Again - look at my previous post.

    UHF does not go through steel reinforced concrete very well if at all.

    The FCC knows that there is a problem, but there is no short term solution to the problem. VHF - especially around channel 6 is affected by FM radio signals in the same area in about the same frequency as the television signals. There is no way to use a pre amplifier in the Philly market.

    The only advice I can give you is to forget everything you knew about analog television and listen to anyone that has experience with digital communications and do what they say.

    Put your antenna outside, at least 10 feet above the main roof of your house.

    Point the antenna directly at the market you wish to receive.

    Use a large antenna, not something that looks like it came in a box of cereal.

    Use the best RG 6 coax you can get your hands on and the best F type crimp on terminals.

    Good Luck!

    For all the apartment dwellers who lives on the wrong side of the apartment building, sorry - but you are out of luck!
     

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