The Official AVS Antenna and Related Hardware Topic! - Page 391 - AVS Forum
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HDTV Technical > The Official AVS Antenna and Related Hardware Topic!
kevm14's Avatar kevm14 04:58 PM 09-25-2009
Quote:
Originally Posted by rabbit73 View Post

I forgot to ask you: Are you able to add another channel from a different direction after your initial scan without erasing the initial scan channels?

If you're not familiar with media center here's how Vista Media Center does it: there is an initial channel scan upon first initialization of a tuner. You are then advised to visit the signal strength test screen where it will loop through all available channels (available meaning they are known to the electronic program guide by your zipcode) and display signal strength in bars, 1 to 6. Generally I've found that anything 3 bars and below is probably marginal.

Inside the screen, you can check or uncheck individual channels which removes them from the EPG and stops scanning them on the loop. I can go back at any time and run this loop and uncheck or check different channels. I can also manually add a channel, which is the only way to add sub-channels in Vista Media Center. I think this is what you were asking but all I'd do based on what I mentioned above is go back into that scan screen and either check off channels I think I might get now, or just check them all off and let it cycle through everything a couple times before I go back and remove the dead ones.

Windows 7 Media Center handles this WAAAAY better (including displaying the ATSC Vchan and subchannel in the correct format), as I am running Win 7 RC1 on a laptop and first tried the tuner on it, where it did a great job of finding the stations AND subchannels.

rabbit73's Avatar rabbit73 05:04 PM 09-25-2009
Thanks.
My knowledge of Media Center is very slight.

Do your tuners give bit errors as well as signal strength, and if so in what form?

I hope you will let us know how your project worked out.
kevm14's Avatar kevm14 05:05 PM 09-25-2009
Quote:
Originally Posted by Dave Loudin View Post

At TVfool, you can plot station azimuths on a Google satellite map (use "Start maps" option). If you can zoom in far enough, you can see pretty accurately how to aim based on landmarks.

I already had satellite map data. I'm saying in new england the tree density is just too high to locate anything meaningful on a map like that. Not to mention I can't really even see the street that the transmission path crosses.

Anyway, I just measured the antenna magnetic bearing. It is 47 degrees. Most of my channels are at 41d. 3 are at 28d (Boston, 50 miles). And 28.1, that I am working on, is at 83d (30 miles). Maybe I'll try moving the antenna 10-15 degrees to the right and hope I can gain 28.1 without losing the Boston stations at 28 degrees.

Or I'll get the CM2020 and hopefully get it all. And if I am REALLY super lucky, it will have a large enough gain section at the tail to receive 69.1 @ 257d, only 19 miles.
kevm14's Avatar kevm14 08:43 PM 09-25-2009
Found some info.

http://www.starkelectronic.com/cm2018.pdf

http://www.starkelectronic.com/cmant.htm

Search the page for 2018 and 2020. There are some gain and beam width specs. I am going to make a rudimentary plot in Excel and see if anything jumps out at me. The beam width is given in terms of -3dB and F/B is the front to back ratio. It doesn't tell me the shape but perhaps it's the same width as the front, just less gain by the F/B column?





If RF 22 is off axis from the others, which do I want? 2018 has a wider beam but 2020 has higher gain. Since RF 22 @ 83d is 30 miles and the Boston channels are at 28d, perhaps 2018 would actually be a better choice. They both lose about 15dB on the back. I wonder if that would leave me with enough on that RF 17 channel behind me.

Here is the composite plot of both antennas' beam width and gain. I think that the 2018 may be the superior choice because of its wider beam in the RF channels of interest. The strong ones I get at 41d are likely not an issue. If I want to get RF 22 @ 83d without losing RF 19 and 20 @ 28d, it seems the width of the 2018 would overrule the 2020's gain here. Thoughts?



Ok, last edit before bed.
Look at my TV fool survey again.
http://www.tvfool.com/?option=com_wr...8ecd4ed4d356de

There is both an ION (RF 32) and a CW (RF 41) @ 29d (more 50 mile Boston stations). Perhaps an alternate plan is use the narrower beam 2020 and point it between 28 and 41 and get everything. And bonus, Boston's ION is 720p according to the Silicon Dust website. Interesting.
holl_ands's Avatar holl_ands 07:13 AM 09-26-2009
FYI: For those of you contemplating using YA-1713 (Ch7-13) antenna to receive Ch6.
According to 4nec2 simulation runs, on Ch6 Raw Gain=2.5 dBi, F/B=0.4 dB and SWR=300
(using YA-1713 measurements from a year ago) or SWR=150 (per Ken Nist's file posted on
www.hdtvprimer.com several years ago).
The earlier YA-1713's had significantly different element spacings and diameters.

Below Ch6, the Gain remains above 2.0, but the SWR keeps climbing.....into the thousands....

So, yes it has some positive Gain, but doesn't suppress multipath coming from the rear
and has excessive SWR that could result in a null on Ch6 for certain cable lengths
(so add extra cable length until it goes away), but also causes lots of reflections up and down
a long coax, which looks like short delay multipath and can degrade Ch6 receptions (YMMV....)
Direct connect to a Preamp should minimize this latter problem if overload isn't an issue....
holl_ands's Avatar holl_ands 07:35 AM 09-26-2009
Quote:
Originally Posted by rabbit73 View Post

I'm skeptical about a manufacturer claiming that an antenna has wider beamwidth and geater gain because the two are mutually exclusive. An antenna must have narrower beamwidth to have greater gain. Perhaps they were quoting the VHF-hi section beamwidth as the beamwidth for the antenna even though the UHF beamwidth might be different.

The 2018 is suitable for your situation, but sometimes, because of so many factors, you just have to try it.

CM-2018 (et. al.) detailed specs are in the fol. catalog:
http://www.channelmasterintl.com/doc...a_20090417.pdf
Note that 45-deg beamwidth applies to highest UHF channels, narrows down to 35-deg for mid-UHF,
widens out to 54-deg for low-UHF and widens even further (as expected) for Hi-VHF....

But are conveniently missing from where they should be (hidden actually) on the C-M website:
http://www.channelmaster.com/product...ID=32&catID=33
http://www.channelmaster.com/support...%20Guide29.pdf
kevm14's Avatar kevm14 07:43 AM 09-26-2009
Quote:
Originally Posted by holl_ands View Post

But are conveniently missing from the C-M website:

I found this:

http://www.channelmasterstore.com/Pr...Show=TechSpecs

Does anyone have any input on how the CM-2020 compares with the Winegard 7697 or 7698? Cost is not the concern...these are all cheap. I just want the superior product. Looking for gain and BW specs or a chart for the Winegard antennas. I'll post if I find anything, comparing them to the CM's.

EDIT. Done. Wow, the Winegard products appear to be noticeably superior to the Channel Master pair. With that much gain, am I at risk for tuner overloading for my 19 mile stations?


hayj's Avatar hayj 09:27 PM 09-26-2009
Quote:
Originally Posted by kevm14 View Post

EDIT: I looked into the jointenna product. It says there is significant attenuation for channels directly adjacent to the blocked channel. 69.1 is RF 17. I have a 50 mile Boston PBS at RF 19 and the Boston ABC I don't want to lose at RF 20 (though I have RI PBS and RI ABC available). 21 is a RI PBS and 22 is the 28.1 that I am trying to receive stronger. Are any of these in danger of being attenuated with the jointenna?

I'm using a jointenna for channel 19 but still wanted 17. I tested the drop in signal level for 17 and found it to be roughly 9dB. I had enough signal so everything worked fine.
kevm14's Avatar kevm14 07:43 AM 09-27-2009
I think I've devised a way to just use an antenna with good gain pointed in a narrow 13 degree beam to capture all the RI stations from 41d and hopefully all the Boston stations from 28-29d. Going by TV Fool, ION (RF 32) is 25.1NM and -65.7 for power, and this is the weakest station I would need to receive. According to the Feds, I am just on the edge of the map for this station, though I don't know what antenna height they assume.

I think I have the antenna choice narrowed down to either of the Winegards I posted. The 11 foot 7697P or 14 foot 7698P. The 7678P puts in its best showing over 7697P at, you guessed it, RF 32. It has 1.6dB over the 7697P at 32. Is that enough, considering the weakness of RF 32, to go with the 7698P or will I be totally fine with the 7697P?

What I am getting at is I think a 14 foot antenna on my roof might look pretty ridiculous but an 11 foot might be on the edge of kind of OK...but it would be a shame if the 7698P made the difference.
holl_ands's Avatar holl_ands 10:38 AM 09-27-2009
Davird_Jr's Avatar Davird_Jr 11:20 PM 09-27-2009
Quote:
Originally Posted by kevm14 View Post

I think I've devised a way to just use an antenna with good gain pointed in a narrow 13 degree beam to capture all the RI stations from 41d and hopefully all the Boston stations from 28-29d. Going by TV Fool, ION (RF 32) is 25.1NM and -65.7 for power, and this is the weakest station I would need to receive. According to the Feds, I am just on the edge of the map for this station, though I don't know what antenna height they assume.

I think I have the antenna choice narrowed down to either of the Winegards I posted. The 11 foot 7697P or 14 foot 7698P. The 7678P puts in its best showing over 7697P at, you guessed it, RF 32. It has 1.6dB over the 7697P at 32. Is that enough, considering the weakness of RF 32, to go with the 7698P or will I be totally fine with the 7697P?

What I am getting at is I think a 14 foot antenna on my roof might look pretty ridiculous but an 11 foot might be on the edge of kind of OK...but it would be a shame if the 7698P made the difference.

I went from an 11 foot radio shack antenna to a 14 foot winegard and it doesn't look much different from the ground. My signal strength increased almost 5 fold with the biggest gains on channel 6. For low VHF bigger is almost always better. Superior design is important also and winegard has that in spades.
kevm14's Avatar kevm14 06:26 AM 09-28-2009
True, but I've got something that looks like this:


I think I've decided on the 7697P, 11 foot, but I'm kinda hoping someone looks at my TV fool survey and can judge my potential reception from the towers at 28 to 41°, based on the antenna gain plots.

Speaking of which, where did they go?

Ah, permissions issue on my Gallery. Should be fixed now. You guys must have thought I was crazy. Well anyway, check out my gain and beamwidth plots.
kevm14's Avatar kevm14 11:01 AM 09-28-2009
I ordered the WG-7697P. It cost me 2 months of analog expanded cable, or $106. TV Fool has me mostly confident that I'll be able to receive my blue area stations without a pre-amp from 15 feet. And without a pre-amp, I won't need to worry about overloading the tuner with the 19 mile stations. I'll report back how it all goes. I already know to expect the antenna to arrive somewhat compromised from shipping/poor packaging. Hope I can manage the install by myself. If not I'll bribe some friends...

I expect about 24 total channels when I am done. Getting about 12 now, plus 2 marginal ones. I also expect a full 12 of those 24 to be HD. Currently I get about 7 in HD, plus the 2 marginal ones.
onezero's Avatar onezero 02:33 PM 09-28-2009
kevm14,

I think you'll get more stations than you expect. I replaced my old antenna with a stacked HD-9022 and a YA-1713. I went from 28 ch (maybe 16 usable) to 52 with about 40 usable, though you need to speak Spanish or Korean for 1/3 of them. I also have a WD 8275 preamp on now. Here's how bad my area is:


OZ
LL
rabbit73's Avatar rabbit73 06:19 PM 09-28-2009
Quote:
Originally Posted by kevm14 View Post

Speaking of which, where did they go?

Many of us are still here, but if we don't have anything useful to say, we are quiet. Also, we don't want to give any bad advice. If we do, the Moderator or other regulars will shoot us down!
Quote:


Ah, permissions issue on my Gallery. Should be fixed now. You guys must have thought I was crazy. Well anyway, check out my gain and beamwidth plots.

Nice job on the plots. I enjoyed looking at your Gallery by going to the root URL.
Quote:


I think I've decided on the 7697P, 11 foot, but I'm kinda hoping someone looks at my TV fool survey and can judge my potential reception from the towers at 28 to 41°, based on the antenna gain plots.

You showed us your tvfool results and told us what channels you were interested in, you told us about your reception equipment, we talked about the possible options for you, and the appropiate antenna types. The engineer in you has done a good job of analyzing the possibilities, now it is time for you to select an antenna and let the technician in you test it out. When you are up there it might be interesting to temporarily swing your new antenna toward 69.1 (if you decide on a 2nd antenna just for 69.1, it will be a lot smaller being just for UHF).

The reason why you must be the final person to make the decision is because there are still some unique unknown factors at your location that would be difficult to analyze. The main one has to do with the fact that with digital, signal quality is just as important as signal strength while with analog, signal strength was all-important.

The digital tuner has an error correction system (FEC) that will correct a limited number of errors in the digital stream. Once that limit is reached, you will start to see tiles, picture freeze, and dropout when you are at the "digital cliff." Signal quality is measured by BER (bit error rate/ratio). The factors that increase BER and reduce signal quality are:

1. Improper signal level: A weak signal will cause a poor signal-to-noise ratio; a signal that is too strong can overload a tuner or preamp. A nearby FM transmitter can also cause overload, which would require an FM trap.
2. Reflections from multipath problems, static or dynamic.
3. Impulse noise in the reception area (worse on VHF).

It IS possible to have a strong but poor quality signal.

Now you know why (in post 10278) I asked about your tuner/software being able to give BER, in addition to strength. It would be useful if it also gave SNR, which should be at least 15.5 to 16 dB to obtain lock on a digital signal. I use the signal quality bar on my Apex DT502 CECB to tell me about signal quality which helps me to optimize antenna aim after first going for max signal strength.
What adds confusion to good reception is that some tuners are more tolerant of a poor quality signal than others as AntAltMike can attest:
http://www.avsforum.com/avs-vb/showp...8&postcount=16

Because my tuner is also my BER meter, the correlation is good.

Since I don't know your EE area of knowledge, I might be preaching to the choir. If so, sorry.
kevm14's Avatar kevm14 06:28 PM 09-28-2009
Wow that is a bad area. What is your antenna height?

Also I looked up those antennas. They are pretty high gain. How much do you think you lose by splitting? And do you have them pointed in the same direction? You have a lot of stuff at 90d but not everything.

You know what else I realized...you probably don't need a fancy band pass/cut combiner. You might even be able to use a splitter backwards. What do you use?
kevm14's Avatar kevm14 06:40 PM 09-28-2009
Quote:
Originally Posted by rabbit73 View Post

Many of us are still here, but if we don't have anything useful to say, we are quiet. Also, we don't want to give any bad advice. If we do, the Moderator or other regulars will shoot us down!

Actually that comment wasn't directed at a person. It was an expression of frustration because I loaded this thread this morning from work only to realize my plots weren't showing! They showed at home when I posted because I was signed into my Gallery as an admin but I forgot to turn on a setting that allows guests to view the original size of an image. I didn't mean to sound like I was whining or something.

Quote:


Nice job on the plots. I enjoyed looking at your Gallery by going to the root URL.

Thanks and thanks.

Quote:


The engineer in you has done a good job of analyzing the possibilities, now it is time for you to select an antenna and let the technician in you test it out. When you are up there it might be interesting to temporarily swing your new antenna toward 69.1.

I knew I was at that point and that is why I placed the order today. Good news, too - the antenna has shipped from Solid Signal and will arrive by wednesday!!

I know I get stuck in the research phase far too long but I have just been burned for what like seems over and over again for making decisions faster than I feel comfortable, only to lack the full comprehension of the situation. In many cases, I've found that if I was a little more patient I would have done a better job at whatever process or product is being discussed.

Quote:


The reason why you must be the final person to make the decision is because there are still some unique unknown factors at your location that would be difficult to analyze.

I do have a few trees very close to the antenna but I am hoping that by pointing the antenna to ~32-35d instead of 47d I will miss the big white pine trunk. There's a smaller tree that I can get rid of myself. I just had 4 giant white pines removed from my front yard 2 weeks ago, by the way.

Quote:


The digital tuner has an error correction system (FEC) that will correct a limited number of errors in the digital stream. Once that limit is reached, you will start to see dropout, tiles, and picture freeze. Signal quality is measured by BER (bit error rate). The factors that increase BER and reduce signal quality are:

I am using a USB tuner at the moment and will be upgrading to an internal PCIe card with a dual internal tuner when I build my HTPC. That's another reason why I am concerned. I guess if I had to add a preamp I will, especially if I end up missing one of the networks I don't have a duplicate of.

Generally, I think external consumer electronic set top tuners, as well as those built into newer TVs, are regarded as being more sensitive than the PC-based internal or external devices.

I have no way to determine signal strength (other than the 6 bars in Media Center), unless I find some software that I can download and use independently of media center just for setup purposes. No idea on FM.

And I'll check that thread out.
rabbit73's Avatar rabbit73 07:03 PM 09-28-2009
Quote:


I know I get stuck in the research phase far too long but I have just been burned for what like seems over and over again for making decisions faster than I feel comfortable, only to lack the full comprehension of the situation. In many cases, I've found that if I was a little more patient I would have done a better job at whatever process or product is being discussed.

I know the feeling well. Been there, done that.

Your fmfool report for zip 02852:


kevm14's Avatar kevm14 07:23 PM 09-28-2009
I never use FM but...that seems like a lot. Am I going to have a problem?
dvansowhat's Avatar dvansowhat 08:44 PM 09-28-2009
Quote:
Originally Posted by kevm14 View Post

I never use FM but...that seems like a lot. Am I going to have a problem?

Wish I had that problem
kevm14's Avatar kevm14 01:01 PM 09-29-2009
Is my "problem" enough to require an FM trap?

Also, I guess this is life in southern new england. I'm just lucky that my home's location works out so RI station transmitters and many Boston transmitters are within a 13° beam spread of each other. The WG 7697P comes tomorrow. The day of reckoning...or perhaps it's more of a weekend job.
ray50's Avatar ray50 01:51 PM 09-29-2009
Just took down a huge HD8200P and added an 2nd XG91 (all stations I want are now UHF). I now have a vertical stack with the two XG91s about 4' apart. They are combined on the mast and feed a Winegard AP-8275. I expected a BIG improvement over 1 XG91, but see only a very small improvement (a few % maybe). I used equal length 6' RG6 to the combiner (http://www.directdepot.net/product_i...ducts_id=22826) to the preamp. Maybe horz. stack is better but vert. was easy because I had a 4' mast to add. Shouldn't I see a bigger improvement??
300ohm's Avatar 300ohm 08:37 PM 09-29-2009
Quote:


Generally, I think external consumer electronic set top tuners, as well as those built into newer TVs, are regarded as being more sensitive than the PC-based internal or external devices.

Theyre getting better. I recently got a (open box at Newegg, $37) AVerTV Bravo Hybrid PCI-E which has a 6th generation tuner. Directly testing it on the same line, and at the exact same time as my Zenith DTT901 CECB, the PCI-E card drops out just a millisecond before the DTT901 does on a weak signal. And its about a millisecond slower to recover.
kevm14's Avatar kevm14 08:41 PM 09-29-2009
Quote:
Originally Posted by 300ohm View Post

Theyre getting better. I recently got a AVerTV Bravo Hybrid PCI-E which has a 6th generation tuner. Directly testing it on the same line, and at the exact same time as my Zenith DTT901 CECB, the PCI-E card drops out just a millisecond before the DTT901 does on a weak signal. And its about a millisecond slower to recover.

I had picked out the Avermedia Duet since I want a dual tuner with internal splitter. Any thoughts on that one? It is fairly new as well. Newer than the other competing dual tuner on the market, the Hauppauge 2250 (which also does NTSC).
Digital Rules's Avatar Digital Rules 08:50 PM 09-29-2009
Quote:
Originally Posted by kevm14 View Post

I never use FM but...that seems like a lot. Am I going to have a problem?

You should be fine. With a 7-69 antenna, you are likely OK unless you are right on top of any strong FM station(s). (0-5 miles)
Larry Kenney's Avatar Larry Kenney 02:15 AM 09-30-2009
I've got a new Antennas Direct Clearstream 5 and am very pleased with how it works. I wanted something that would pick up the two VHF stations in this market without having to use a rotor. (A rotor and DVR don't work well together. ) The C5 was listed a multidirectional antenna, so I thought I'd try it. I planned to couple it up with the Antennas Direct SR-15 I have for UHF.

Well, much to my surprise, with the antenna pointed toward Mt. San Bruno at 178 degrees and peaked for KNTV channel 12, I not only get a good signal on 12, but KGO on channel 7 is coming in at 33 db SNR from Sutro Tower which is to the west at 267 degrees.

But that's not the end of the story. I'm also getting excellent signals on ALL of the UHF stations on Sutro Tower and Mt. San Bruno, plus decent signals from all of the stations transmitting from the hills above Fremont 35 miles to the southeast, including a low power 12.2 kw station. That's with just the C5 by itself... no SR-15.

The C5 is a weird looking antenna, but it seems to perform very well. Now I can use the SR-15 for something else.

Larry
SF
The Wizard's Avatar The Wizard 06:58 AM 09-30-2009
Quote:
Originally Posted by Larry Kenney View Post

I've got a new Antennas Direct Clearstream 5 and am very pleased with how it works.

Can anybody else second this?
I thought early users of the C5 hated it and sent it back, there being no good substitute for a Yagi-style antenna for receiving high VHF...
hayj's Avatar hayj 07:45 AM 09-30-2009
So I installed my hdp-269 and it works great. Channel 19 comes in fine after the jointenna and a two way split. My antenna is on the eave of the house so the cable drops into the attic and through a ceiling, and then connects to the tuner in a closet, so its a short run. To test it before I got on the roof, I put it in-line at the end of the run before the jointenna. Everything works fine now so I'm tempted to leave it there as opposed to mounting it on the mast, outside exposed to the elements. Is there any reason not to if things work fine? Am I overlooking something due to inexperience?
Digital Rules's Avatar Digital Rules 08:58 AM 09-30-2009
Quote:
Originally Posted by The Wizard View Post

Can anybody else second this?
I thought early users of the C5 hated it and sent it back, there being no good substitute for a Yagi-style antenna for receiving high VHF...

If you live in an area with very low levels of multipath, and decent signal strength, the C-5 may work just fine. A real windy day is the real test for such a non- directional antenna.
ProjectSHO89's Avatar ProjectSHO89 10:56 AM 09-30-2009
Quote:
Originally Posted by The Wizard View Post

Can anybody else second this?
I thought early users of the C5 hated it and sent it back, there being no good substitute for a Yagi-style antenna for receiving high VHF...

Nonsense. According to a little birdie, returns have been less than 2% and most of them were from people who didn't know what they were doing or self-selected the wrong antenna. About 1/4 of the returns were never even assembled.

Most posters here (on AVSforum) only come on when they have problems. You rarely hear the success stories. Station engineers who received samples of the C5 to try out have reported excellent results. One even reported good results with it on VHF-5 at about 25 miles, something that was unexpected.

Quote:


If you live in an area with very low levels of multipath, and decent signal strength, the C-5 may work just fine. A real windy day is the real test for such a non- directional antenna.

At about 6 dbd on high-VHF, the C5's gain is almost exactly the same as the recommended antena gain that the FCC uses in calculating service coverage (OET-69 Planning Factors).

The C5 is basically a scaled-up C1. It exhibits similar beamwidth (70°) and F/B performance (around 10-12 dB based on testing). It is classified as "multi-directional". Gain-wise, it's roughly equivilent to a 5-element Yagi but with a broader beamwidth. However, it isn't 5 feet long which makes it an attractive option for a lot of people. Of course, if greater gain and/or directivity is needed, then a 10-element Yagi would be suggested.

I played with a C5 a couple of weeks ago using my 1454 hand-held spectrum analyzer. I was able to see the signals on the SA screen from VHF stations on 8 & 12 from over 70 miles away at a height of only 10' above ground (good atmospherics that day!). I am in the middle of two VHF-8 stations and could see both of them when the antenna was pointed at each. I was able to get a partial decode on them with my USB tuner, but I forgot to bring a power supply for my pre-amp with me so I wasn't able to try it with a pre-amp. Maybe some other time...

FWIW, the TVfool forcasts for those stations are pretty dismal: http://www.tvfool.com/?option=com_wr...8ecd9b7d0e4ccd
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