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Recommend a good indoor ota antenna.

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by fochs13, Apr 25, 2007.

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  1. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Dec 9, 2006
    Under mounting supplies: http://www.solidsignal.com/prod_display.asp?prod=WMXFMRPT
    I think you're going the right way with this & would bet the antenna will work fine.
    There is no "new tech" for antennas, a good VHF/UHF antenna is and will always be a good antenna until: it gets broken, bent, or way too rusty.
     
  2. funhouse69

    funhouse69 Icon

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    Mar 26, 2007
    I couldn't find that transformer for the life of me but is exactly what I'm looking for. I will order one up and give it a try. Like I said I've got nothing to loose and saving the money I would spend for a new antenna to gain. I will keep you posted. Thanks again - This site is the BEST!
     
  3. FranklyFred

    FranklyFred Legend

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    15-1892 works great for me. Used a basic rca amplified antenna got all my locals but had to move the antenna a lot .This one picks them all up with no moving it around once I got it dialed in. The one has a nifty remote control to fine tune it with it.
     
  4. funhouse69

    funhouse69 Icon

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    Mar 26, 2007
    Well I've got a few updates to my OTA Experience. I mentioned I've got an old Radio Shack UHF / VHF Antenna in my Attic. I also got Terrestrial Digital DB4 Antenna as well.

    Over the weekend I gave them both a try with very disappointing results. According to Antennaweb.org all of the OTA Stations I want to get are only a few miles away from my house (all under 5 miles) and all with in the same compass direction. I first tried the new antenna (DB4) with an all new cable run. I fired up my Slingbox Pro to help me fine tune the antenna location / orientation (which made life a whole lot easier) and while I could get 100% signal on 4 of my stations I couldn't seem to get any happy medium where I could get them all in the same range some of them we not reading at all.

    This brings me to a question - what is a good OTA Signal? I know 100 is awesome but what is the minimum needed to have a reliable signal? Through D* I do get my major network locals which are Channel 4, 5, 7 and 25. I don't get Channels 2, 38, 44 or 56. I really want to get 2 and 44 as they are my local PBS and have several substations on each. I would bet money that 2 & 44 are broadcast from the same location but no matter what I would get one tuned in with good signals (like 70's or better) then the other would be in the toilet or not even reading at all :eek2:

    I then went back to the good old Radio Shack Antenna, I attached a new matching transformer to it and the same new cable run and started playing with that set up. While I was able to get higher signals on some stations the same thing happened where I would get some high to or even close to 100% I would never be able to get that happy medium.

    Finally on the channels that I do get good signals on say 80+ I tune them in and I get nothing but black screen for say 10 to even 20 or more seconds then I will eventually get a picture and it will be fine. Sometimes I will have to change the channel and go back to get it to show up. I've rebooted the unit (through the remote) and even gone through the antenna set up again and still have the same issues. I will even get the occasional searching for signal message, when I check the levels they will be in the upper range say over 70 and not fluctuating much.

    Oh and for this I turned Native Off so I'm set to 1080i Stretch just for this well and my SlingBox Pro which seems to have some issues re-syncing when Native is on.

    Any thoughts / suggestions?
     
  5. hasan

    hasan Well-Known Member

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    Sep 22, 2006
    Ogden, IA
    It sounds like multi-path to me. You may be getting reflections, and these are particularly difficult for the HR20 tuner. If you have other channels that are analog near the same frequency as the digital channels you are trying to receive, look at them with your standard TV (using the same antenna), and see if you have ghosting on those channels. If you do, that is multi-path.

    Curing multi-path:

    1. On UHF, you need a highly directive antenna, i.e., one that has a narrow front beamwidth and good front to rear rejection. A highly directive antenna will discriminate against reflections, both off to the side and from the back or rear of the antenna. Go to solidsignal.com and look at some of the higher gain uhf antennas.


    2. Once you have a fairly directive antenna, move it around a bit...back and forth (toward and further away from the transmitting complex), as well as left to right with respect to the transmitting complex. At this point, I'm not talking about changing the direction of the antenna (turning it), I'm only talking about moving its "mounting point" in your room/closet/attic. After trying this, you can then swing the antenna back and forth (turning it) to eliminate refections.

    Since you are so close to the transmitter, strength is probably not the issue, reflections probably are. You can also try a variable attenuator to get the reflections low enough (while still maintaining desired signal strength) that they drop off....however, this is not likely to work...the ratio of desired to ghost signal is not changing with the attenuator, just the raw strength of both signals together. It might help, but I'd do most other things first.

    On VHF you have the same problems, BUT it is harder to get a highly directive antenna on these lower frequencies. Notice on the fancy rabbit ears you have a "rotary phase switch" to help eliminate ghosting on VHF. If you have ever used the switch you will also notice that it isn't terribly effective much of the time.


    If I were in your situation, I would do the following:

    1. If your OTA-HD is UHF only, get a highly directive antenna and put it in a closet or attic. You can try the Radio Shack U-75 (40 inches long with screened corner reflector at about 25 bucks) in a closet. You can try a much larger XG-71 (model number might be wrong, check solidsignal) in an attic, with corresponding higher cost, 80 bucks or more, as I recall.

    2. If you need VHF as well as UHF, you will have to do either attic or outdoors, period. I would get a medium sized channel master. No less than 5 VHF (longer) elements. The UHF side will be fine in the medium sized dual band channel masters)
     
  6. houskamp

    houskamp New Member

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    Sep 14, 2006
    Also make sure you use the hr20 signal meter to tune antenna.. using a "analog" tv to tune will give very bad results...
     
  7. funhouse69

    funhouse69 Icon

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    Mar 26, 2007
    Thanks for the info - So the DB4 Antenna I got is not a good antenna for Multi Path Rejection? Just for a test I took the cable off of my HR20 and put it on my TV and did the Digital Channel Search and it came up with a whole lot more than the HR20 did that's for sure. I was able to get all of the channels and then some that I get on the HR20 with no issues so I guess the HR20 is a little more picky.

    I currently have both Antennas in my Attic (3rd Story), in the front of my house which is the direction where my OTA Transmitters are. I live on a hill and should have a pretty straight shot. I will try moving the DB4 around and maybe even to the other side of the house to see if that will help. I have been using the HR20 signal meter as my guide as it is what I want to get my OTA's on and not the TV directly unless of course I'm recording 2 things and don't want to watch either of them or a 3rd.

    Also what is a reasonable cable length before signal loss? As I mentioned I have all new cable however it is 100' long. I will cut it once I find a permanent home for the antenna.
     
  8. hasan

    hasan Well-Known Member

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    Sep 22, 2006
    Ogden, IA
    The DB-4 (if I recall correctly) is a bow tie array in front of a reflecting screen. If that is true, it is not very directive across the front (it does have decent rejection off the back). It has a broad front lobe that invites multi-path. If I suffered from multi-path at the distance you are looking at, I'd pony up the 25 bucks for the radio shack u-75 (uhf yagi with corner reflector). The DB-4 is UHF only, so I have to assume you are getting your OTA-HD from UHF sources only. If you are using the DB-4 for VHF as well, it doesn't work well and may result in receiving reflections on VHF, due to the terrible pattern distortion on VHF.

    100' of feedline is a LOT of loss. Since you are very close, I would try the U-75 with your existing feedline to start. You are probably losing about 75% of your signal or more in that 100' of RG-6. It is possible, since you are so close that you can afford to lose that much and still get a good signal, as long as you get rid of the multi-path (which the U-75 should help dramatically with)

    So:

    1. Get a U-75 and try it, both in the HR20 and the TV itself.

    2. Be sure to look at some analog channels on your TV with the U-75 and see if you get ghosting. If you still see ghosting on analog uhf channels, you are seeing multi-path.

    3. If you don't have multi-path and still can't get the stations that ARE IN THE HR20 GUIDE, then think about shortening the feedline or putting a mast mounted preamp at the antenna....not some garden variety distribution amplifier...a REAL antenna preamp designed specifically for mounting at the antenna. A good one is the Channel Master 7777...again, check with Solidsignal.com

    If you do go to a mast mounted preamp, then you can leave the 100' feedline at its full length, as the preamp AT THE ANTENNA completely makes up for the feedline loss.

    Once you have the antenna mounted preamp, you have no need for any distribution amps in the house...just use good quality passive splitters. (this is true for your situtation specifically, as you are near the transmitter complex)
     
  9. gcisko

    gcisko I am Iron Man!

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    Sep 27, 2006
    I Live about 35 miles from the chicago towers according to antennaweb.org. I used to have a big honkin "normal" tv antenna in my attic. It was there when I bought the house. reception was OK but I could not get the local CBS (WBBM-DT, 2-1). So I gave the Phillips MANT90 a shot. I also went to ACE hardware and added their larger video booster to the signal. The results are awesome. Everything is rock solid even WBBM-DT, 2-1.

    Also now with the latest software for the HR20 (158) all my OTA's are great.

    One thing about the meter strength test. I do not believe it. It shows 30% for WMMB-DT, 2-1 yet the TV picture is rock solid. In previous software revisions, PBS WTTW-DT, 11-1 would show close to 100% but upon watching TV it would pixelate and break up. So I only trust what I seen on the TV Picture.
     
  10. funhouse69

    funhouse69 Icon

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    Mar 26, 2007
    I thought I would post an update to my previous e-mails in this thread. Today swapped the DB4 from it's home in the front of my attic to a big wooden box so I could move it around :D. With this and a whole lot of spare cable in mind I went to the opposite end of the attic and managed to get all of my desired locals in a range of upper 70's to just about 80 on the low end and 100 on the high end with very little fluctuation. I had a few things scheduled to be recorded of some of these channels so I didn't mess with it any further. The surprising thing is that I've got the antenna facing almost the complete opposite direction as to where according to Antenna Web it should be facing. Hey whatever works right? Once I get things set up I will cut the cable down by at least half and will be interested to see if that makes a difference in the channels that are in the 70's and 80's.

    Thanks again for all of the help. This is the place where obviously someone has been there / done that / Got the T-Shirt which saves all of us new guys a whole lot of time and aggravation for sure!
     
  11. hasan

    hasan Well-Known Member

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    Sep 22, 2006
    Ogden, IA
    If moving the antenna (as I suggested in a prior response to you) solved your problem, it was/is most likely multi-path, as any signal > 50% should produce a perfectly viewable signal. Anything in the high 50's here is rock solid. As far as pointing (even in the wrong direction) making a difference, that also indicates a multi-path problem (being solved). What you are doing by "mispointing" is nulling out the objectionable reflection(s) / multi-path signals.

    Glad you made progress. You may find that going to a more "directive" array (one less sensitive to side and back lobes) would have done the job in the existing location, but that would have necessitated buying another antenna, that's why I suggested moving the antenna first.

    Let us know how you make out with the change in feedline length, although if I had things working the way you do now, I WOULDN'T CHANGE A THING. You are getting all your stations and the weakest are in the 70s....that's plenty. If you cut the feedline, you may introduce "phase" or "mismatch issues that you don't have now. I would leave well enough alone, unless you actually have "weak" signals...a consistent signal in the 70s is NOT a weak signal, nor will increasing it give you a better or more reliable signal. Make sure you really have a problem before you try to solve it.:)
     
  12. gcisko

    gcisko I am Iron Man!

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    Sep 27, 2006
    Any time I saw a signal in the 50's it usually (90% or more) would fluctuate between below 50 and above so you would get an inconsistant picture. OTAs do bounce, at least they do for me. The idea is you want the low end to be no lower than 50%. This usually means the high end to be 70%-80%. BTW, many of mine are pegged at 100% with the HR20...
     
  13. hasan

    hasan Well-Known Member

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    Sep 22, 2006
    Ogden, IA
    I get no fluctuation more than 10% and typically for most channels it is < 5%.

    You say "The idea is that you want the low end to be no lower than 50%....", is a common mistake. The meter in the HR20 is NOT measuring signal strength....far, far from it. It measures a variant of BER (bit-error-rate), which is the standard for digital quality measurements. Signal strength, unless it is quite low, has no effect on the BER.

    The most common cause of variations in the HR20 signal meter is multi-path...as reflections cause data loss (due to signal subtraction and other distortion), the BER goes up, therefore the HR20 meter goes DOWN. The actual signal strength in terms of carrier to noise may not have gone down at all, but the BER has gone up and the HR20 "Signal Quality" meter goes down.

    There are 3 possible causes for a high BER (hence low signal on the HR20):

    1. Too strong a signal (amplifiers ahead of the HR20) overdrives the HR20 tuner input, causing distortion of the data stream.

    2. Ghosting (in the old analog language)/Multi-path (reflections as noted above)

    3. Weak signal so the data stream isn't far enough out of the noise to reliably extract the data stream.

    The most common cause of high BER is #2. If you get good uhf analog signals in terms of strength, then you can probably rule out #3. (assuming your HD OTA signals are UHF) Similar test for VHF: if you get good vhf analog signals on your "regular" tv using the same antenna, then you can probably rule out #3.


    #2 can be most easily cured by using a highly directive antenna which has a very narrow front lobe, thus high side-lobe rejection, as well as good rejection off the back.

    As others have noted, the HR20 tuner seems to have poor multi-path performance. Once you get rid of that, it seems to do pretty well. I have very good luck with mine.

    The real "idea" is to get the BER to be STABLE, not jumping around, and greater than 50%. A jumping BER is a VERY BAD SIGN, and a high probability indicator that you have bad multi-path. Eliminate that (per above), and you should be fine.
     
  14. funhouse69

    funhouse69 Icon

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    Mar 26, 2007
    Well I finally had some time to tweak things a little more and I wanted to post the results. The first thing I did was go to Antenna Web one more time to make sure that I had all my information correct. At the same time I read about another site that offers a similar service. So off I went to HDTV Magazine's website which (in my opinion) is a whole lot better / more valuable. Originally I thought that all of the OTA's that I've been trying to get were all being transmitted from the same place when in fact they aren't. Today I went and picked up a trusty compass and with the transmitter directions in hand I moved my DB4 back to the front side of my attic against the southern wall and to my amazement with practically no tweaking whatsoever I got all of channels with excellent signal strength! All of the channels are in the upper 90's to 100 and the lowest is in the upper 80's with almost no bounce. Interestingly enough they seem to tune in a lot faster but we also had the new national release pushed last night so that might have something to do with it as well.

    I almost forgot to mention that before doing this I cut more than half of the cable out of the picture last weekend but didn't change the antenna placement at all. This means that I probably have about a 40' run now instead of the original 100'. This surprisingly made no noticeable difference in signal according to the HR20.

    I'm still having the issue with channel 5-2 which I don't think has anything to do with the HR20. When I try and tune this channel in I get nothing but a black screen. From there when I go to my next OTA Channel either say 7-1 or 5-1 it will not tune in at all still same black screen. I don't get any error messages or anything. I have to go to a D* local HD channel and it takes a good 20+ seconds to tune in after that I'm good to go. It seems that 5-2 is some kind of blackhole or something that messed up the OTA tuner :eek2:
     
  15. Monty23

    Monty23 Icon

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    Sep 16, 2006
    I've had a CM 4221 for a couple years in my attic and it works really good. It is also somewhat smaller than the 4228.
     
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