# ASK DBSTalk: Question on OTA tuning



## sleepy hollow (Aug 25, 2003)

In addition to enjoying the heck out of my new 921 over the weekend I am trying to determine the best way to get OTA broadcasts. Most of the issues are likely my own fault for having a house with aluminum siding and an attic antenna. However, I wanted to confirm whether there may still be issues with tunner lock on the 921. DTV scan seems to find all of the stations in my area (DC/VA), but the lock on the stations is pretty poor. Cannot watch any of them. Also, the network stations show as 7.1 and 9.1, etc. 

First, how can I monitor signal strength for these stations, so I can troubleshoot my antenna installation (I am only 14 miles from the towers and have reasonably clear LOS)? 

Next, are there still some bugs to be rectified in the tuner lock? If the station is found by DTV scan should it tune reasonably well? 

Finally, I was able to watch local CBS affiliate in DTV/HDTV fro a time. The broadcasts seem to change from 4x3 to 16x9. In some cases, though, I'd swear the 4x3 was HD, or close, especially for a live sporting event. Am I nuts or is it the difference between a sat with compression and a broadcast without compression that I am seeing?

thanks


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## Mark Lamutt (Mar 24, 2002)

sleepy hollow said:


> First, how can I monitor signal strength for these stations, so I can troubleshoot my antenna installation (I am only 14 miles from the towers and have reasonably clear LOS)?


Menu - 6 - 1 (I think - the Point Dish screen)
In the tuner box, down arrow to the Off-Air option
scroll to the channel in question - it will show you signal strength for that particular channel.



sleepy hollow said:


> Next, are there still some bugs to be rectified in the tuner lock? If the station is found by DTV scan should it tune reasonably well?


Yes, there are still some issues. Most stations lock, but some with problematic PSIP data are causing the 921 serious grief.



sleepy hollow said:


> Finally, I was able to watch local CBS affiliate in DTV/HDTV fro a time. The broadcasts seem to change from 4x3 to 16x9. In some cases, though, I'd swear the 4x3 was HD, or close, especially for a live sporting event. Am I nuts or is it the difference between a sat with compression and a broadcast without compression that I am seeing?


The 4x3 picture you were seeing was the standard definition signal being upconverted to 1080i. The 16x9 widescreen images you were seeing were the high definition ones.


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## 4HiMarks (Jan 21, 2004)

sleepy hollow said:


> I am only 14 miles from the towers and have reasonably clear LOS


I am about the same distance north of the towers (Laurel), and I had similar problems picking up DC stations, although Balt. came in fine even though it is farther. I had the guys from Fairfax Antenna come out a week ago. They checked out the possibility of an attic installation, but it was a no go (I also have some aluminum siding). They put a Winegard on my roof (sorry, don't know the model) and I pick up the DC digitals with no trouble now, except for WDCA. Some people on the Washington D.C. / Baltimore HD Information thread http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=275834 over at AVS Forum who are also in NoVa say they get Balt. better than DC too, even though it is 3 times as far!

-Chris


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## sleepy hollow (Aug 25, 2003)

Thanks, 4himarks. I have always been able to get OTA balt stations in analog. Unfortunately I think I would need a rotator or a second antenna since the DC and Balt towers are in quite different directions.

I think the siding is giving me trouble, though, so I may have to settle for only one or 2 stations at the moment. [Maybe I can get my wife to allow me to replace the siding (18 years old) since she does not want any more gadgets on the roof, but that's another story.]

Mark, I know about the menu-6-2 screen, but how do I enter "7.1" for a channel to try to max the signal from ABC, for example? Antenna.org also confirms ABC is 7.1. Funny, though, when doing a scan I show 0 channels found until I get close to 15, so I wonder if the channel numbers like 7.1 are actually in VHF?

Anyone know what's up?


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## 4HiMarks (Jan 21, 2004)

Sleepy Hollow:

This discussion probably belongs in the Broadcast forum. Or, go to that AVS Forum link I provided. The first page of the thread has a listing of all the DC-area channels and a lot of other resources. The digital channels broadcast on UHF and the 921 "remaps" the numbers in the guide according to some information transmitted with the signal, referred to as PSIP. So, for example WJLA-DT 7.1 actually broadcasts on UHF channel 39. http://www.2150.com/broadcast/ will tell you the exact distance, compass heading from your location, and channel asignments.

-Chris


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## Mark Lamutt (Mar 24, 2002)

If 7.1 is being broadcast on channel 39, scroll in the point dish screen to channel 39 to adjust your antenna.


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## sleepy hollow (Aug 25, 2003)

Thanks, I think I can take it from here, though I do not happen to know the lat/long of my house. I guess I'll go look for that conversion tool first...


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## Mark Lamutt (Mar 24, 2002)

Mapquest used to provide Lat/Long for a street address, although I don't know if they do still or not.


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## sleepy hollow (Aug 25, 2003)

Found one at maporama.com. Just type in the address and it will show you a map with lat/long in degrees and decimal at the bottom of the map display. 

Got all the DTV station info as well. This helps a lot. 

What is really strange is that for DC, 3 of the major nets are b'casting from the exact same direction (possibly same towers). Yet, when I could pull in CBS (WUSA) I could not get ABC or FOX. 

But I'm not done yet. Will play around this weekend and see if I can get to the bottom of this.


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## 4HiMarks (Jan 21, 2004)

Mark Lamutt said:


> Mapquest used to provide Lat/Long for a street address, although I don't know if they do still or not.


You can get it here .

-Chris


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## sleepy hollow (Aug 25, 2003)

Well, I wanted to close out this thread just in case there are any others out there who are as ignorant as I was about antennas.

I was really scratching my head about why I could not get lock on the major networks from my attic antenna. I am 15 miles from the broadcast tower for all major networks with clear line of sight.

I spent my lunch hour yesterday researching UHF antennas on the web. I read and read article after article about gain, calibration, shapes, etc. I visited every major antenna manufacturer's site to read what they had posted. I visited the industry organization sites. I even read a very technical article about the relative performance of various antennas, and what equipment could be used to optimize antenna placement. I had several strategies mapped out and was planning them for this weekend.

Until I happened to read a very small comment on one manufacturer's page just as I was clicking away from it. Almost missed it. It was in none of the articles or tutorials I read.

The comment stated something to the effect that the reader should remember that the end with the smallest elements is the end to be pointed in the direction of the signal. Well, I am sure all of you knew that, but I admit it, I thought pointing an antenna meant exactly that. My attic radio shack antenna is shaped like an arrow. Who would have thought pointing meant anything other than pointing? Turns out I was trying to aim the antenna to do the absolute worst job of acquiring signal lock. It worked great, too. I was most successful! Could not lock on anything.

Anyway, I wanted to confess my stupidity to all of you [while also noting that the information that cause my breakthrough was completely missing from everything I encountered except that little note I did finally come across].

Maybe I will have saved some other poor unfortunate dope the trouble I have gone to because of my bad assumption.

Anyway, the bottom line is - absolutely nothing wrong with my 921 - I am getting all local channels with great lock. Do not even need the signal amp that has been attached to the antenna. Works better without it (must be noisy).

The 921 is now truly a beast of a machine!


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## jtp1947 (Feb 13, 2004)

sleepy hollow said:


> Well, I wanted to close out this thread just in case there are any others out there who are as ignorant as I was about antennas.
> 
> I was really scratching my head about why I could not get lock on the major networks from my attic antenna. I am 15 miles from the broadcast tower for all major networks with clear line of sight.
> 
> ...


Sleepy hollow, when you had your antenna pointed the wrong way, were you able to get your local OTA channels even though you couldn't lock on them? I can get my local DTV channels, but no signal strength whatsoever on any of those channels when I go to point dish. I don't know if I am doing something wrong or not since I am getting the channels in the Los Angeles area. Thanks, Jim


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## sleepy hollow (Aug 25, 2003)

jtp1947 said:


> Sleepy hollow, when you had your antenna pointed the wrong way, were you able to get your local OTA channels even though you couldn't lock on them? I can get my local DTV channels, but no signal strength whatsoever on any of those channels when I go to point dish. I don't know if I am doing something wrong or not since I am getting the channels in the Los Angeles area. Thanks, Jim


Yes, I could get one or two to show me some pixilated screens, but unwatchable. When viewing the signal strength screen, I got sequences something like 0, 40, 80(lock), 40, 0, 90 (lock), 0, etc. Never stayed at any reading more than a few seconds.

Now I have constant lock ranging from 90's to 120's.

At the point dish signal strength screen, make sure you are tuning to the off air broadcasts, not one of the satellite transponders and that you have the right channel number dialed into the screen.

I had to look up the UHF channel for each network station since they were showing as 9.1 (CBS), 7.1(ABC), and 4.1(NBC) in the guide. the actual broadcast channels are all in the 30's which is the middle of the UHF spectrum (300 Mhz to 3 Ghz). This fact makes it even more likely that if I could get one, I'd get them all since the wave characteristics are more similar the closer the frequencies are to each other.

hope this helps. My guess is that you simply have the wrong channel entered, so are getting no reading.


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## jsanders (Jan 21, 2004)

sleepy hollow said:


> I spent my lunch hour yesterday researching UHF antennas on the web. I read and read article after article about gain, calibration, shapes, etc.


The information was probably there too, since you mention shapes. The yagi (log periodic) antenna is a directional antenna, and the it has a specific gain pattern to it, you probably saw the shape of it, bigger on one end and pretty much nothing on the other end. This shape has to be referenced to something on the antenna, in this case it is referenced to the end with the smaller elements.

Not all antennas work that way, you can get a UHF omnidiretional antenna, and it doesn't matter how it is oriented.

Think of a complelely sphirical balloon. That is the pattern for an omnidirectional antenna. Now, consider that the balloon has a specific volume to it that can't be changed (for purpose of simplicity of example only). If you want the balloon to go farther in one direction, you need to squease the other end of the balloon. That is what the directional antenna does. You get a bigger gain on one side, with the sacrifice of gain on the other. It has the added benefit of rejecting -some- multipath, bounced signals that come in from the other side of the antenna.


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## lujan (Feb 10, 2004)

sleepy hollow said:


> Yes, I could get one or two to show me some pixilated screens, but unwatchable. When viewing the signal strength screen, I got sequences something like 0, 40, 80(lock), 40, 0, 90 (lock), 0, etc. Never stayed at any reading more than a few seconds.
> 
> Now I have constant lock ranging from 90's to 120's.
> 
> ...


How or where did you look up the UHF channels?


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## sleepy hollow (Aug 25, 2003)

jsanders said:


> The information was probably there too, since you mention shapes. The yagi (log periodic) antenna is a directional antenna, and the it has a specific gain pattern to it, you probably saw the shape of it, bigger on one end and pretty much nothing on the other end. This shape has to be referenced to something on the antenna, in this case it is referenced to the end with the smaller elements.
> 
> Not all antennas work that way, you can get a UHF omnidiretional antenna, and it doesn't matter how it is oriented.
> 
> Think of a complelely sphirical balloon. That is the pattern for an omnidirectional antenna. Now, consider that the balloon has a specific volume to it that can't be changed (for purpose of simplicity of example only). If you want the balloon to go farther in one direction, you need to squease the other end of the balloon. That is what the directional antenna does. You get a bigger gain on one side, with the sacrifice of gain on the other. It has the added benefit of rejecting -some- multipath, bounced signals that come in from the other side of the antenna.


Thanks for the education. I am sure you are right, but it was not obvious (to me at least) how the shapes in the graphs were linked to the direction of the elements. I also was convinced that I had mine pointed properly so would have overlooked it in any case, probably. It took a clear unambiguous reference to jolt me from my directional fever.

I knew there were omnidirectional UHF antennas, but mine is a vhf/uhf combo that has the longer VHF elements at an angle to the center axis to make it fit in the attic better. Hence my conviction that "pointing" an antenna and "pointing" MY [arrow-shaped] antenna were the same.

Always something more to learn though and that is great fun.


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## jsanders (Jan 21, 2004)

I have to admit that it is very counter intuitive the way it works. It really should have been better spelled out as to what direction it is supposed to be pointed. Sorry about your troubles. Hopefully anyone installing an OTA antenna can clearn from your experience.


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## ypsiguy (Jan 28, 2004)

sleepy hollow said:


> In addition to enjoying the heck out of my new 921 over the weekend I am trying to determine the best way to get OTA broadcasts. Most of the issues are likely my own fault for having a house with aluminum siding and an attic antenna. However, I wanted to confirm whether there may still be issues with tunner lock on the 921. DTV scan seems to find all of the stations in my area (DC/VA), but the lock on the stations is pretty poor. Cannot watch any of them. Also, the network stations show as 7.1 and 9.1, etc.
> 
> First, how can I monitor signal strength for these stations, so I can troubleshoot my antenna installation (I am only 14 miles from the towers and have reasonably clear LOS)?
> 
> ...


The 4x3 SD picture you see on 8-VSB DTV broadcast is more than likely on the broadcaster's HD channel. They mostly do 1HD + 1SD channel format in the Detroit area, so the OTA SD channels looks very similar to Dish's because the compression and bandwidth are pretty similar. 
Glad to hear you got the antenna working, OTA DTV beats the heck outta analog when it's finally up and running.


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## jsanders (Jan 21, 2004)

ypsiguy said:


> The 4x3 SD picture you see on 8-VSB DTV broadcast is more than likely on the broadcaster's HD channel. They mostly do 1HD + 1SD channel format in the Detroit area, so the OTA SD channels looks very similar to Dish's because the compression and bandwidth are pretty similar.
> Glad to hear you got the antenna working, OTA DTV beats the heck outta analog when it's finally up and running.


This sounded a bit confusing to me. What dish channels are you comparing them to? Dish channels are compressed to be below what I would consider watching. Analog cable looks a lot better than digital cable (which is compressed), and it looks a lot better than say CNN on Dish (which is highly compressed and pixelized).

Now, if you're saying, "OTA DTV beats the heck outta analog when it's finally up and running", then wouldn't that mean that the OTA SD channel *isn't* compressed as much as the dish channel?

I think that is the case depending on how the multicast is done. If it is 720p, you can have an SD channel that looks good without much in terms of bandwidth compression.

If OTA SD looks better than good analog, and good analog analog looks better than Dish, or digital cable, then doesn't OTA SD look better than dish, or digital cable??


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## jsanders (Jan 21, 2004)

Ah! Maybe your talking about a difference between the multicast channel and the dish channel? I still would imagine the multicast channel would look better than the dish one.

One really cool multicast channel here is KGO 7-3. All it does is show the doppler radar for the bay area. I tune to that one to see if any rain clouds are coming before I leave to do something. Multicasting is cool..


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## jtp1947 (Feb 13, 2004)

lujan said:


> How or where did you look up the UHF channels?


I found the info. on www.nab.org, click on televisions on the left side menu, and then click on digital stations in operation on the right. Jim


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