Antenna Advice for Austin, TX

Magnepan · 29-Nov-2011, 4:34 AM

Hi all, I've been plagued by sporadically spotty TV reception for a while and I'm hoping someone can help me rule out some of the possible culprits before I spend a bunch of money solving problems I don't have.

You'll probably laugh when you look at the TVFool Signal Analysis, since this should probably seem close to ideal, but here it is anyway.

The only things I really care about are the first 6 entries on the list which are all green. Every single one of them is:
within about a 9 degree spread
< 5 miles away
full LOS
> 70 dB NM
> -18 dBm Pwr
No co-channel warning
No adjacent channel warning
All UHF except Fox which is channel 7

If you look at the signal analysis, the entire plot is basically red, because I also live at the top of a decent sized hill.

Should be easy, right? Here's the rub. My antenna currently sits by a window that's basically the exact opposite side of the house that the signals are coming from.

I also realized way after the fact that my primary antenna (Zenith Silver Sensor Indoor Antenna) is only supposed to be tuned for UHF, and fox is on VHF7, but I usually get pretty decent reception on it. It's getting my computer to give me a reliable picture on KXAN, KVUE, KNVA, and KEYE that seems to be my real problem.

My current equipment setup (from source to destination):
Choice of Indoor Antenna (Previously mentioned Silver Sensor, old Rabbit Ears,
~25 feet of RG-6 (didn't measure, I just know it's more than I really need)
3-way splitter feeding 3 of the following 4 (RCA from Home Depot?)
\RG-59 -> VBox Cat's Eye 150 (ATSC Tuner Card for my PC) #1
\RG-59 -> VBox Cat's Eye 150 (ATSC Tuner Card for my PC) #2
\RG-6 -> SiliconDust HD HomeRun (dual tuner for my PC)
\RG-6 => Dish Network VIP 722 (normally not connected, but I can use it for testing)
All tuner cards are plugged into an HTPC running Windows 7 and Media Center.

I never really use the Dish DVR for watching OTA broadcasts since there's no useful guide information, but I've used it for testing on a few occasions. All of the channels seem to come in fairly well on the Dish DVR with a rated signal of 60-75 (presumably out of 100), but I've never really tried it for more than 10-15 minutes.

On the HTPC, I usually get a good signal when testing, but then the same channel after a while (days? hours?) will go through periods of stuttering. The HTPC has plenty of relatively new parts and is fairly overpowered for its purpose so there should be no real hardware limitations.

When testing in things like the SiliconDust HDHomeRun app, which uses 3 criteria, I see:
signal strengths well above 90%
signal quality anywhere from 65-95% (occasionally dropping to the 60s)
symbol quality usually a solid 100%

Given my location, could I be in danger of being overpowered? Should I try an attenuator?
The chart doesn't seem to think so. Is it possible that I've got multipath issues from the antenna being in a bad spot of my house? It's a bit frustrating to tweak the antenna position and feel like I've got great reception only to have it get choppy 24 hours later with a clear sky in the middle of a football game.

I also picked up a RCA ANT 1400R flat antenna yesterday just to try it out, but I haven't gotten a chance to plug it in and see if this would be any better.

Given my suboptimal window locations, should I even bother trying a larger indoor antenna like a Winegard SS-3000?

If I decide to try an external antenna, would something like an RCA ANT 751R be a good choice?
What about a Winegard HD 7694P? I saw one of those at Fry's yesterday.

Are both of these complete overkill? I was also looking at something like a Winegard MS-1000, but it doesn't seem like I really need to worry about the omnidirectional nature. This would pretty much just be for the smaller footprint.

The other elephant in the room is problems with the tuners, but given a lot of people stating that they haven't had problems with the same equipment, I imagine the hardware is OK. As far as the software goes, it's really hard to tell if I've got a solid base to work from. When I go through the Media Center signal strength meters on my vbox cards, the signal seems to always show either 100% or 0% on the VBox Cards and 4 to 5 out of 5 on the HDHomeRun.

The only other stations I might even consider watching are either broadcasting from the same set of towers as the channels I've mentioned or are within 50 miles and 90 degrees away (I think I could pull in Spurs games from the San Antonio CW Affiliate), but I honestly don't care if I can't see them.

P.S. I can find 2.1 and 62.1 on scans but the picture usually isn't consistent.

Magnepan · 30-Nov-2011, 4:57 AM

Sorry for the multiple posts. I missed the part about requiring a moderator the first time, and my laptop actually crashed right when I did the second one.

MisterMe · 30-Nov-2011, 2:08 PM

The thing that jumps out at me is that you are splitting your signal nine ways to Sunday for reasons that are not terribly clear. Three separate HTPC tuners? There are HTPC tuners that tune two channels at the same time. Would it not be better to connect your antenna to your Slingbox and let it distribute your signals? The takeaway message is that you have chosen a brute force solution for what you want to do. You should consider a more elegant solution.

Magnepan · 30-Nov-2011, 3:59 PM

Quote:

Originally Posted by MisterMe

The thing that jumps out at me is that you are splitting your signal nine ways to Sunday for reasons that are not terribly clear. Three separate HTPC tuners? There are HTPC tuners that tune two channels at the same time.

I use it to record multiple stations at once.mostly on college football Saturdays when there could be games on CBS, NBC, and ABC at the same time.

The Hdhomerun that I mentioned is a dual tuner.

This is actually pretty common in the HTPC world.

GroundUrMast · 30-Nov-2011, 5:58 PM

You do have the option to edit or delete your duplicate posts.

I run three HDHR dual tuners. My experience so far is that they are the most critical tuners in the house. If they like a signal, the tuners in the traditional TVs and STB will have no trouble.

Do I understand correctly, that one 3-way splitter feeds three 2-way splitters? How many tuner inputs are connected? (My HDHR dual tuners have two inputs each.) Are any splitter ports unused? If so, are the ports terminated with 75 ohm termination caps?

The metering available to you via the hdhomerun_config_gui.exe utility (located at C:\Program Files\Silicondust\HDHomeRun on my XP PC) is quite useful. Of the three reported parameters, Signal Strength, Signal Quality and Symbol Quality, Signal Quality is the most useful diagnostic measure. Widely and or rapidly varying Signal Quality is an indication of some type of interference, multipath, impulse noise, etc. Signal Quality indications near 50% indicate you are at the threshold of Symbol errors which are errors at the output of the decoder's error correction process. When a symbol error occurs, it's going to show as a video or audio defect at the display.

The bottom line is, I'll get a higher quality recording when I see low signal strength with stable signal quality. High signal strength and low or rapidly varying signal quality will almost always produce poor recordings.

Any Symbol Quality indication other than 100% is going to show as a visible or audible defect. The refresh rate on the metering shown by the hdhomerun_config_gui.exe utility may allow many single symbol errors to go unreported in real time. That's why I pay attention to the Signal Quality.

I would prefer an outdoor antenna. The quality of the signal is less likely to be affected by electrical noise produced in the home. Outside, in the clear, there will be less chance of reflected signals producing multipath interference. And of course there will be more signal power available outside (which is lowest on my list of priority).

A Winegard HD7694P will have far more gain and directivity (multipath rejection ability) than any indoor antenna. The output of that antenna at your location would have no trouble driving a passive 8-way splitter.

If you choose to use an indoor antenna, you'll want to find a location and aim alignment that produces the highest stable signal quality indications.

Then... there are Ethernet auto-negotiation problems that can occur. Failure of the NICs to agree on speed will always show up as a failed connection (no data transfer). Failure to agree on duplex (full or half) will result in data loss as it transits the Ethernet link.

Magnepan · 1-Dec-2011, 4:04 AM

Quote: