This is topic Over the air HDTV antennas - recommendations? in forum The Afterlife at Film-Tech Forum ARCHIVE.


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Posted by Bobby Henderson (Member # 840) on 02-04-2008, 11:14 PM:
 
What brand/model of antenna do you use to pick up over the air HDTV broadcasts?

I need to get a better outdoor antenna for picking up more HDTV channels. The old one I'm currently using is able to pick up all the analog channels in the Lawton-Wichita Falls TV market. It also picks up the digital channels Lawton's ABC affiliate is now broadcasting (at first you needed to be connected via the local cable TV company's digital cable service).

I need a new antenna sensitive enough to pick up Wichita Falls' digital channels. And if the antenna is good enough it may even pick up channels in Oklahoma City. But it seems to be tricky getting the right antenna.

I have a Dish network account, but the local channels carried on it are not available in HD. And our local ABC channel is just squeezing and cropping its 720p digital channel, down-sampling it and giving that to the satellite companies to re-broadcast. Kinda sucks.
 

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Posted by Joe Redifer (Member # 3) on 02-04-2008, 11:33 PM:
 
I have a Terk something-or-other, but it is amplified and that actually seems to help.

The problem is that nobody is broadcasting digital at full power yet until they build a new tower in the mountains. Hopefully sometime this year I'll get better reception. Whenever the wind blows or the trees grow leaves, my reception gets jumpy and I miss the punchline to one of Jay Leno's AWESOME jokes.
 

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Posted by Paul Mayer (Member # 355) on 02-05-2008, 04:13 AM:
 
For your application Bobby, I think any good high-gain antenna will work. High-gain antennas, as typically used in fringe reception areas, are also quite directional. A narrow beam pattern is desirable with digital signals since such patterns will help reject off-axis signals and cut down on multipath interference.

Multipath with analog signals just means seeing "ghost" images. Multipath with digital signals can cause the baseband part of a receiver to have difficulty locking to the incoming bit stream - resulting in signal dropouts even though the RF signal strength and the RF part of the receiver is working just fine.

The over-the-air part of ATSC in this country was designed primarily for outdoor antenna use. Indoor "rabbit ear" style antennas may work, but the system was designed and optimized with outdoor antennas in mind. The situation was made a bit worse when the FCC decided to go with 8VSB (8 Vestigial Side Band) as the US OTA modulation standard. Most of the rest of the world went with COFDM (Coded Orthogonal Frequency Division Modulation), which is much more robust in multipath-prone areas, such as cities and urban areas. 8VSB works best in areas where there are not a lot of structures or other objects that cause the signal reflections that lead to multipath interference. Since its adoption as the US OTA standard, there have been improvements to 8VSB which have improved its multipath performance.

One drawback to highly-directional antennas may be the need for multiple arrays or a rotator. From Lawton, the angle between Wichita Falls and OKC is about 110 degrees is it not? You may need one of those solutions to obtain the best signal quality from both directions.

Interesting back story (or not) - In the late '90s the engineers at Sinclair Broadcasting saw this potential problem area and tried to get the FCC to approve both modulation schemes for OTA use. Some manufacturers even began making dual-scheme ATSC receivers and STBs, but then the FCC went with 8VSB only.

The conspiracy theorists say this was a deliberate decision designed to hobble OTA ATSC in the hopes of getting everyone to switch to cable. Then the spectrum currently designated for OTA ATSC can be auctioned off - more money for the feds. No more free OTA signals. You want access to that programing? Pay for it then. Take that story with as big a grain (or rock) of salt as you need.
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-05-2008, 09:56 AM:
 
Actually NOT ANY old antenna will work all that well. HDTV is transmitted on the UHF band which presents its own specific set of problems as Paul mentions, especially with multipath. Most of the combo antennas I've worked with seem to put most of the engineering dollar into the vhf section and not into the uhf. Unless you are really still wanting to spend $$ on the soon to be obsolete VHF spectrum then purchasing a strictly UHF antenna is in your favor, especially if you have any fringe stations you're wanting to pick up. At 110 degrees spacing apart a rotor is more or less mandatory. Since you want about 1000uv's down at the television antenna terminals you have to select an antenna with the correct amount of gain to get you there... more than 1000uv at the terminals and you stand to overload the front end of the ATSC tuner. In your area the Weingard HD-9095P is a good bet. I am using the HD-9075 here at home and get a two thirds signal level on all the stations that transmit from Farnsworth Peak. We are lucky to have all the DTV signals comming from more or less one place on the mountain here in SLC as there is no multipath problem what so ever.

Mark
 

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Posted by Bobby Henderson (Member # 840) on 02-05-2008, 10:05 AM:
 
I suspect our local network stations are not broadcasting in HD at full power either. The local Fox affiliate, KJTL has a couple different towers, one of which is in Oklahoma about 30 miles from here. But according to antennaweb.org, I would need a more powerful "violent zone" rated antenna to receive the signal, which suggests KJTL is not putting much power behind their DTV signal. Other affiliates may still be broadcasting over the air in analog. You need a "blue zone" rated antenna to get decent reception of their analog signals.

Obviously it seems like the broadcasters may be trying to save money on electrical bills by not broadcasting their DTV signals at greater signal strengths. The Lawton-Wichita Falls market covers a pretty big area of territory, so whenever the complete switch to digital broadcasting happens those stations may even need to install more transponder towers to cover bigger chunks of rural areas.

One thing I wondering, which channel will each broadcast station give up when analog broadcasts are ended in 2009? Channel 7 here in Lawton is, obviously, channel 7. Will they just start sending out a more powerful digital signal in that space? Or will they be stuck with their other frequency and possibly a different channel number?

I was looking at a couple of outdoor antenna models from Terrestrial Digital. Their products are featured on the antennasdirect.com web site. Their DB8 model looks like it might do the trick for capturing signals from Wichita Falls. OTOH, I worry about how that kind of antenna will hold up in Oklahoma weather. High wind and hail from severe storms probably wouldn't be very nice to such equipment.

It's tempting to contact management at the local affiliates to see what their plans are regarding over the air digital broadcast over the next year. Again, I'm wondering if they will install more signal transponders. Lawton and Wichita Falls are in the same broadcast market, but are an hour's drive apart.
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-05-2008, 10:13 AM:
 
You may be right about the low power... many DTV Stations are still running temporary 1000 watt transmitters(PBS in Reno is one), some of them were installed in just a few days time. That is all "supposed" to be temporary though. When the VHF units are switched off permanently these stations will more than likely see construction permits come through for much higher power permanent installations. The Denver area is(was?) another DTV problem area with only temporary transmitters operating because the "Tree Huggers" were preventing construction of a new tower on one of the mountains. Also, there are some markets that simply cannot afford to operate both transmitters, Casper, and Cheyenne Wyoming are two of those that will be strictly VHF to the very end. Contacting the involved stations is a good idea... ask to speak to the "Chief Engineer" or at least the "assistant chief" if they have one... the average tech in the studio is unlikely to know what the actual transmitter plans are. BTW: The channel 7 thing... from what I've head the VHF spectrum will be sold off mainly for beefing up emergency channels.

There are more new fangled antenna companys sprouting up claiming all sorts of needs for receiving DTV but for the most part its pure bull shit....kinda like Bose. 10db gain is only so-so performance from the Terrestial. Nothing works better then a high end Weingard or Channel Master antenna... I've put up literally hundreds of them over the years. Some of my installs in the Chicago Burbs could swing the antenna around and pick up Indianopolis!! Your home owners insurance should cover any damage to your antenna that might happen... Have also done alot of "inisurance" type of work in that regard!!

Mark
 

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Posted by Bobby Henderson (Member # 840) on 02-05-2008, 11:46 AM:
 
That's good to know about the antennas. Judging from some of the online reviews the Weingard model you mentioned appears to be a good choice. It may turn out to do the job much better once the local broadcast affiliates have pushed all their transmitting power exclusively to their digital channel(s).

It's funny you mention the "tree huggers" in Colorado. The last few times I visited Colorado Springs I noticed cell phone towers being painted forest green and having little metal fake tree branch looking things attached. The end result is more obnoxiously cheesy looking than any cell phone tower I've ever seen. The Black Forest area north of the 'Springs has a few of them. Quite laughable.
 

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Posted by David Stambaugh (Member # 1102) on 02-05-2008, 12:09 PM:
 
OTA TV reception here in Eugene is very problematic. First, the transmitters are evenly divided between two different locations, like 100 degrees separated. Then there are hills and valleys etc. to contend with. I live in one of the valleys, still within city limits and only 10 miles from the most distant transmitter(s), yet OTA reception is horrible, even on VHF. UHF is even worse.

In a situation like that, with transmitters in different locations, can 2 directional UHF antennas be combined to cover both sources? Or is a rotator the only option?

BTW, I have a Zenith Silver-something indoor UHF antenna. I am not impressed. I also have an RCA amplified indoor UHF antenna, wasn't very expensive, but it seems to work fairly well if you set it up carefully. I've tried an amplifier on the Zenith and it does help but it's still very fussy and can't bring in a steady digital signal from FOX.
 

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Posted by Mitchell Dvoskin (Member # 751) on 02-05-2008, 12:39 PM:
 
Over the years, I have not had much luck with amplified antennas. Most amplify more noise than signal.

I am about 40 miles northwest of Manhattan, and I get all the New York HD stations perfectly with my 20 year old Radio Shack roof antenna.
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-05-2008, 12:45 PM:
 
David,
I think in your case the optimum reception is only going to happen by rotor and medium gain directional UHF antenna. Downtown Chicago has similar problems to yours but is mainly due to buildings reflecting the signals. You certainly don't need any high gain stuff like Bobby may need f you're just 10 miles from the towers. A rotor is the only way to point directly to the actual tower(s) when they are that far spaced... otherwise you'll be watching the multipath and not the signal. Omnidirectional antennas are also not going to help at all... you need to pinpoint the signal to elminate the ghosting(multipath).

Mark
 

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Posted by Bruce Hansen (Member # 281) on 02-06-2008, 09:58 PM:
 
There will still be some DTV broadcasts on VHF after Feb. 16, 2009. For example here in Atlanta, NBC's DTV is 10 (NTSC is 11), one of the PBS DTVs is 12 (NTSC is 8). There are no plans that I know of to sell of VHF TV freqs, but UHF TV CH 52-69 will be sold off some time after 2-16-09. Check the FCC web site to find what channels will be in use in your area. (here is one place I found a list, but I don't knwo if it is the latest version: http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-06-1082A2.pdf

BTW, if you want to apply for your (up to) two $40 off coupons for the downconverters to use with your old TVs and DVD recorders that don't have DTV tuners, go to www.dtv2009.gov . The coupons will be sent out when the converters come to market. At this time, they think this will happen in late Feb. or early March.
 

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Posted by Joe Redifer (Member # 3) on 02-06-2008, 10:16 PM:
 

quote: Bobby Henderson

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Channel 7 here in Lawton is, obviously, channel 7. Will they just start sending out a more powerful digital signal in that space? Or will they be stuck with their other frequency and possibly a different channel number?

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quote: Mitchell Dvoskin

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Over the years, I have not had much luck with amplified antennas. Most amplify more noise than signal.

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Well that isn't really much of a problem with DTV since it isn't analog. You simply can't get noise in the picture. Artifacts, yes, but that just comes from the super crappy MPEG 2 technology which was invented before Columbus came to America. MPEG 2 is for fools. With my TV, it has a diagnostics menu which shows the signal strength of an ATSC channel. Turning the amplification down generally lowers the number from 70 to 42.
 

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Posted by Bobby Henderson (Member # 840) on 02-06-2008, 10:24 PM:
 
Actually, KSWO's DTV channel here does register in my TV as channel "7.1." And I think that sort of sucks because I can just see some doofus seeing "KSWO DT 7.1" on the channel label and think they're broadcasting in 7.1 surround sound.

 

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Posted by Ron Funderburg (Member # 4561) on 02-06-2008, 10:54 PM:
 
The ABC affiliate out of OKC doesn't broadcast strong enough to get it where I live just south east of Chickasha. The reason given is that they step on the Lawton signal if they broadcast strong enough to get here, but we don't get the Lawton stations here so how can that be right?
 

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Posted by Bobby Henderson (Member # 840) on 02-07-2008, 12:23 AM:
 
Are you not picking up KSWO's DTV signal or are you not picking up KSWO at all, digital or analog?

If you're not even getting KSWO's analog signal that would seem strange since it can be picked up in Wichita Falls, which is farther from Lawton than Chickasha. About 15 or so miles farther.

I think the stations around here are just being cheap with their electrical power usage. They probably figure too few people in this area are using HDTV to make the effort of broadcasting powerful DTV signals worth it. They also likely figure the few that do have HDTV are getting local channels through digital cable or something.

Guess we'll be waiting until sometime next year before DTV signals in SW OK will be strong enough to get over the air at significant distance.
 

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Posted by Ron Funderburg (Member # 4561) on 02-07-2008, 11:55 AM:
 
I am not sure Bobby I list tons of stations but only NBC, CBS, Fox, The pbs stuff and some religious channels come in all out of OKC but my outside high def antenna isn't out side it is up in a window frame because I don't have a poll to put on yet! My bad on that! ABC out of Oklahoma City isn't received by any of the people in the Chickasha area on the digital signal.

Oh I need to get that darn poll up and get the antenna out of the house!
 

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Posted by Frank Angel (Member # 248) on 02-08-2008, 04:19 AM:
 
I have had the very same problem with amplified antennas (in fact that same Terk or Trek or some such that Joe has -- call it Drek) and like Mitchell, it is hardly worth the effort. It amplifies everything -- signal and noise -- which is as good as nothing.

I was told that a GOOD UHF outdoor antenna is all you need to pick up HDTV. Years ago one UHF station went PBS and I wanted to watch it but I was getting terrible reception with my combo antenna (you know....90% worth of UHF elements and a wussy little 10% piece of crap stuck on the end of it for UHF). I wrote to the FCC asking what to do and they sent me a pamphlet (my tax dollars at work) that explained that UHF reception needn't be inferior to VHF reception if you have the right antenna. They directed me to get a UHF-only antenna with a four bow-tie array behind a screen grid. It's been working great ever since. I am hoping when I finally hook up my Sharp LCD HDTV, I won't have to change anything and this UHF antenna will do the trick.

Luckily I have a clear view of the Empire State Building which is only like 5 miles away as the birds fly....that's practically a direct wire from the transmitters to my TV. Alas, I used to have the same line-of-site to the WTC towers.
 

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Posted by Joe Redifer (Member # 3) on 02-08-2008, 06:06 AM:
 

quote: Frank Angel

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I have had the very same problem with amplified antennas (in fact that same Terk or Trek or some such that Joe has -- call it Drek) and like Mitchell, it is hardly worth the effort. It amplifies everything -- signal and noise -- which is as good as nothing.

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quote: Joe Redifer

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I'm not sure who you're responding to, but as I just said the amplification does indeed help the digital signal. Who cares about analog signals? Nobody.

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Joes is correct on this... a little amplified noise hitting a digital receiver is irrelevant. Most DTV's can make a great picture and sound with very little signal...
 

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Posted by Frank Angel (Member # 248) on 02-08-2008, 11:03 AM:
 
Question: since the vast majority of OTA antenna inputs on TV receivers require 75 ohm impedence, how come almost all antennae are balanced at 300 ohm which then need a those crappy little transformers made in China which have to have a good deal of inherent loss, especially given how precious is the signal you are trying to capture. Why not just construct the antenna itself as being 75 ohms thus eliminating any need for a matching transformer going into the 75 ohm coax?

Joe, I was agreeing with Mitchell about the bad luck he and I have had with amplified antennas over the years on analog OTA signals. One of those that I had tried was the Trek antenna and it was rubbish....again, for analog TV.
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-09-2008, 01:49 PM:
 
Well, I guess if you do buy those matching transformers that are made in China they are probably going to have alot of loss... and probably alot of lead in them too . Truth is that you can still purchase decent 300:75 ohm matching transformers if you seek them out. Also using RG-6 coax for the UHF feed is mandatory if you look at the losses in RG-59 at the UHF frequencies. Keep in mind however that a couple db signal loss with DTV is not going to matter one iota.

Mark
 

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Posted by Frank Angel (Member # 248) on 02-10-2008, 02:27 PM:
 
Understood, Mark, but that still begs the question -- why make all antennas with 300 ohm impedence when the vast majority of equipment wants to see 75ohm input and almost all installations will use 75ohm downlink cabling? It would be like all microphones being made with 10K outputs and requiring everyone who uses them to put a transformer to drop them down to 600 or 150 ohm input. Constructing an antenna with a 75ohm impedence to match the equipment that it's expected to be connected to would be a very simple and logical change, and I would imagine, fairly inexpensive. Unless there is some specific reason that 300ohms works better to gather up the signal or perhaps it's more practical that 75ohm (could 75ohm require too large elements?...I have no idea how the impedence is physically constructed).
 

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Posted by Paul Mayer (Member # 355) on 02-12-2008, 02:22 AM:
 

quote: Frank Angel

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Why make all antennas with 300 ohm impedence when the vast majority of equipment wants to see 75ohm input and almost all installations will use 75ohm downlink cabling?

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quote:

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'Cause it's cheap!

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quote: Frank Angel

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So how come they can't make a shielded 300 ohm cable, like the dual-core that Belden makes so it avoids RF junk?

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Its possible that something like that may exist... I never looked. At any rate RG-6 is made in such huge quantities that even adding the cost of a good 300:75 ohm transformer to your downrun would still be alot cheaper. I tend to believe that the 300 ohm shielded cable would also be pretty large in diameter. When ever you add a shield you have a capacitor which gives you loss at high frequencies per foot of cable. Cable is specified in pf of capacitance per foot... Any capacitance added will cut those higher frequencies and those signals may be weak to non-existant at the other end of the cable.

A g9ood example of what capacitance does was fpound when I was in chgarge of A-V repair at Wheaton School District. I had to completely re-wire many of the schools master antenna systems because the contractors cheaply installed RG-59 coax... RG-59 has alot of capacitance to say the least and none of the UHF channels made it further than perhaps two rooms distance from the distribution amp... Some of these systems had Jerrold down convertors on them to convert UHF channels to a VHF frequency just so they could have some usable UHF channels... At any rate I replaced all that RG-59 with RG-6 in probably a dozen school buildings... one principal whose system had never worked told me I was the umpteenth person to try to fix it and he actually bet me dinner that I couldn't fix it. Well.. replacing the cable in his building fixed it... a huge Weingard VHF/UHF antenna on top of his 4 story school building also got him several channels in Indianopolis. We used a larger Jerrold distribution amplifier and attenuated the signal feeding each hallway and at each outlet to 1000uv. He bought me dinner. They tore his school down three years later and built a new one...

Mark
 

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Posted by Louis Bornwasser (Member # 3063) on 03-09-2008, 08:28 PM:
 
Yes, at one time in the 70's Belden made 300 ohm, balanced, shielded line. Haven't seen it since the "switch" to RG-6 & clones. Louis
 

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Posted by Mark Gulbrandsen (Member # 72) on 03-10-2008, 12:09 AM:
 
Is that the stuff that had just a foil shield around it??? I remember something like that but 1972 is a long time ago.

Mark
 

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Posted by Frank Angel (Member # 248) on 03-10-2008, 09:26 AM:
 
Geez Mark, that guy got away cheap. You should have opted for dinner every night for a month!

It really is amazing what slipshod work is done by idiots and then has to be fixed later. And mostly I've discovered it happens in municipal outfits rather than corporate entities. I guess that might be because in governement operations, it's not their money they waste. Seems no one ever gets fired when crap like that happens in government; they just use the pubic coffers to fix their mistakes and even cover them up....sometimes over and over. In the private sector, people get their stupid asses fired in the blink of an eye when costly goofs are made.
 

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