Changes in DFW's LPTV market

[eskipper411]

Looks like 34.1 is no longer simulcasting 47.2. Last time I checked it was showing infomercials

What I am waiting to see is what Tropo DX does to KNAV..... KAUZ in Wichita Falls will shatter that signal to pieces on my antenna.

You may be OK. You probably have an antenna with a high F/B ratio, which should attenuate the weaker signal from behind more than 15 dB below the stronger one. But 'burbs SE of Dallas (e.g., Ferris) may see the interference you're talking about, since there'd only be about 60 degrees separation between the signals.

Silly me. That assumed you'd rather watch KNAV than KAUZ. Even though KNAV isn't on the air yet, that seems unlikely. If you're more interested in KAUZ during tropo episodes, interference from KNAV is a bigger problem: it'd probably be the stronger signal, which means you'd need a F/B ratio well above 15 dB. You may need to gang together two antennas with a 1/4 wavelength (just under 6 inches at RF 22) N/S separation and a 1/4 wavelength delay line to null out KNAV.

What is an F/B Ratio? And I do have 2 antennas. One at 40 feet and one at 20 feet. Actually surprised that the 70 mph winds we had on the 20th didn't tear it down.

[JHBrandt]

You may be OK. You probably have an antenna with a high F/B ratio, which should attenuate the weaker signal from behind more than 15 dB below the stronger one. But 'burbs SE of Dallas (e.g., Ferris) may see the interference you're talking about, since there'd only be about 60 degrees separation between the signals.

Silly me. That assumed you'd rather watch KNAV than KAUZ. Even though KNAV isn't on the air yet, that seems unlikely. If you're more interested in KAUZ during tropo episodes, interference from KNAV is a bigger problem: it'd probably be the stronger signal, which means you'd need a F/B ratio well above 15 dB. You may need to gang together two antennas with a 1/4 wavelength (just under 6 inches at RF 22) N/S separation and a 1/4 wavelength delay line to null out KNAV.

What is an F/B Ratio? And I do have 2 antennas. One at 40 feet and one at 20 feet. Actually surprised that the 70 mph winds we had on the 20th didn't tear it down.

Glad to hear your antennas are undamaged. I'm guessing the 40-footer is pointed at Wichita Falls and the 20-footer at Cedar Hill, but feel free to correct me if I'm wrong.

F/B (front/back) ratio is simply the ratio of an antenna's gain toward the front to its gain toward the back. It's not always a useful spec, but in the KNAV vs. KAUZ case (where you're trying to tune in a signal in front of the antenna while rejecting another signal coming from behind) it gives you an idea of how strong the interfering signal can be before you have trouble. Antennas usually have negative gain toward the back; if so, the F/B ratio would be greater than the gain itself.

With digital signals, we need a minimum 15 dB signal/noise ratio to get a lock, and an interfering signal will look like noise. So if we have a reasonably strong signal in front and the antenna has a 15 dB F/B ratio, the signal from the back can be almost as strong as the signal in front before it prevents us from getting a lock.

OTOH, if the signal in front is marginal, then it'll take less signal from the back before there's too much noise to get a lock. That's why I was expecting that, in your case, KAUZ wouldn't interfere too badly with KNAV (assuming KNAV actually broadcasts something worth watching someday), but KNAV would probably interfere with KAUZ.

Finally, let me clarify about using two antennas to "null out" an interfering signal. This is easiest if the two antennas are identical and at the same height, so they both receive equally strong signals. The idea would be to point both antennas toward the signal you want (let's say KAUZ) but arrange them so the signal reaches one antenna a little bit sooner than it reaches the other. Ideally, you want the signals 90 degrees out of phase. For KAUZ, one antenna (I'll call it "antenna A") will be 90 degrees ahead of the other ("antenna B"), but for KNAV, antenna A will be 90 degrees behind antenna B.

Then, you make the coax from antenna A about 4 inches longer than the coax from antenna B, then combine the signals with a common signal splitter hooked up in reverse. The extra coax delays the signal from antenna A by about 90 more degrees, so the signals from KAUZ arrive at the splitter in phase - but the signals from KNAV arrive 180 degrees out of phase, and cancel out!

To do this, you need to move one of the antennas a few inches north or south until you find the "sweet spot" that makes the cancellation work. It's a lot of effort, but if you really want to watch KAUZ, and you can't once KNAV lights up, it might be worth the trouble.

[JHBrandt]

Infomercials have returned to 50.4, and it looks like 50.2 may have programming again soon: the color bars have been replaced with various icons & logos over the past few days.

Looks like 34.1 is no longer simulcasting 47.2. Last time I checked it was showing infomercials

Last night it looked like 34.1 was broadcasting UAN again, but it was no longer simulcast with 47.2.

34.1 continues to bounce around. The channel is now titled "revenue frontier," which is the infomercial network on 55.2; but the programming continues to switch between infomercials and UAN, sometimes simulcast with 47.2 and sometimes not. The infomercials I've seen were not a simulcast of 55.2.

Also, it looks like KBOP/20.2 has gone dark. These are tough times for the videospammers....

Spoke too soon. Infomercials quickly returned to 20.2.

[JHBrandt]

Infomercials have returned to 50.4, and it looks like 50.2 may have programming again soon: the color bars have been replaced with various icons & logos over the past few days.

50.2 is now showing Reino Unido's logo. This was the network they had before going to color bars. Looks like they'll be returning to the air soon.

34.1 continues to bounce around. The channel is now titled "revenue frontier," which is the infomercial network on 55.2; but the programming continues to switch between infomercials and UAN, sometimes simulcast with 47.2 and sometimes not. The infomercials I've seen were not a simulcast of 55.2.

And now KJJM has added back two subchannels. 34.2 is showing infomercials and 34.3 is currently color bars.

Interestingly, 34.2 and 50.4 are making the same technical error. They're both taking a 4:3 program, widening it to 16:9 with pillarboxing, but then broadcasting it as 4:3. This causes DTV receivers to show a double-pillarboxed image with everything squeezed horizontally, so everybody looks like they're 10 feet tall.

It has an amuzing effect on weight-loss/workout infomercials. The "before" images don't look all that bad, and the "after" images all look like Twiggy!

Also, it looks like KBOP/20.2 has gone dark. These are tough times for the videospammers....

Spoke too soon. Infomercials quickly returned to 20.2.

It now looks like the tough times for the Godcasters and videospammers are ending. 50.2 and 50.4 are back, 34 is showing us two channels with infomercials (plus occasional religious programs on 34.1), and of course the new KWDA/30 continues to evolve.

[JHBrandt]

Infomercials have returned to 50.4, and it looks like 50.2 may have programming again soon: the color bars have been replaced with various icons & logos over the past few days.

And now KJJM has added back two subchannels. 34.2 is showing infomercials and 34.3 is currently color bars.

Interestingly, 34.2 and 50.4 are making the same technical error....

Upon further review, 34.2 and 50.4 are actually simulcasting It's not all infomercials, though. They occasionally air an infotainment show called "GBN World News" or something

[eskipper411]

You may be OK. You probably have an antenna with a high F/B ratio, which should attenuate the weaker signal from behind more than 15 dB below the stronger one. But 'burbs SE of Dallas (e.g., Ferris) may see the interference you're talking about, since there'd only be about 60 degrees separation between the signals.

Silly me. That assumed you'd rather watch KNAV than KAUZ. Even though KNAV isn't on the air yet, that seems unlikely. If you're more interested in KAUZ during tropo episodes, interference from KNAV is a bigger problem: it'd probably be the stronger signal, which means you'd need a F/B ratio well above 15 dB. You may need to gang together two antennas with a 1/4 wavelength (just under 6 inches at RF 22) N/S separation and a 1/4 wavelength delay line to null out KNAV.

What is an F/B Ratio? And I do have 2 antennas. One at 40 feet and one at 20 feet. Actually surprised that the 70 mph winds we had on the 20th didn't tear it down.

Glad to hear your antennas are undamaged. I'm guessing the 40-footer is pointed at Wichita Falls and the 20-footer at Cedar Hill, but feel free to correct me if I'm wrong.

F/B (front/back) ratio is simply the ratio of an antenna's gain toward the front to its gain toward the back. It's not always a useful spec, but in the KNAV vs. KAUZ case (where you're trying to tune in a signal in front of the antenna while rejecting another signal coming from behind) it gives you an idea of how strong the interfering signal can be before you have trouble. Antennas usually have negative gain toward the back; if so, the F/B ratio would be greater than the gain itself.

With digital signals, we need a minimum 15 dB signal/noise ratio to get a lock, and an interfering signal will look like noise. So if we have a reasonably strong signal in front and the antenna has a 15 dB F/B ratio, the signal from the back can be almost as strong as the signal in front before it prevents us from getting a lock.

OTOH, if the signal in front is marginal, then it'll take less signal from the back before there's too much noise to get a lock. That's why I was expecting that, in your case, KAUZ wouldn't interfere too badly with KNAV (assuming KNAV actually broadcasts something worth watching someday), but KNAV would probably interfere with KAUZ.

Finally, let me clarify about using two antennas to "null out" an interfering signal. This is easiest if the two antennas are identical and at the same height, so they both receive equally strong signals. The idea would be to point both antennas toward the signal you want (let's say KAUZ) but arrange them so the signal reaches one antenna a little bit sooner than it reaches the other. Ideally, you want the signals 90 degrees out of phase. For KAUZ, one antenna (I'll call it "antenna A") will be 90 degrees ahead of the other ("antenna B"), but for KNAV, antenna A will be 90 degrees behind antenna B.

Then, you make the coax from antenna A about 4 inches longer than the coax from antenna B, then combine the signals with a common signal splitter hooked up in reverse. The extra coax delays the signal from antenna A by about 90 more degrees, so the signals from KAUZ arrive at the splitter in phase - but the signals from KNAV arrive 180 degrees out of phase, and cancel out!

To do this, you need to move one of the antennas a few inches north or south until you find the "sweet spot" that makes the cancellation work. It's a lot of effort, but if you really want to watch KAUZ, and you can't once KNAV lights up, it might be worth the trouble.

Actually, both are pointed at Cedar Hill and usually I feel the need to turn it toward Wichita Falls but is unable to find the "sweet spot" due to my TV's crappy tuner scale. 60% is the limit and is in increments of 20%. 40% and below is unreadable.

[JHBrandt]

Glad to hear your antennas are undamaged. I'm guessing the 40-footer is pointed at Wichita Falls and the 20-footer at Cedar Hill, but feel free to correct me if I'm wrong.

F/B (front/back) ratio is simply the ratio of an antenna's gain toward the front to its gain toward the back. It's not always a useful spec, but in the KNAV vs. KAUZ case (where you're trying to tune in a signal in front of the antenna while rejecting another signal coming from behind) it gives you an idea of how strong the interfering signal can be before you have trouble. Antennas usually have negative gain toward the back; if so, the F/B ratio would be greater than the gain itself.

With digital signals, we need a minimum 15 dB signal/noise ratio to get a lock, and an interfering signal will look like noise. So if we have a reasonably strong signal in front and the antenna has a 15 dB F/B ratio, the signal from the back can be almost as strong as the signal in front before it prevents us from getting a lock.

OTOH, if the signal in front is marginal, then it'll take less signal from the back before there's too much noise to get a lock. That's why I was expecting that, in your case, KAUZ wouldn't interfere too badly with KNAV (assuming KNAV actually broadcasts something worth watching someday), but KNAV would probably interfere with KAUZ.

Finally, let me clarify about using two antennas to "null out" an interfering signal. This is easiest if the two antennas are identical and at the same height, so they both receive equally strong signals. The idea would be to point both antennas toward the signal you want (let's say KAUZ) but arrange them so the signal reaches one antenna a little bit sooner than it reaches the other. Ideally, you want the signals 90 degrees out of phase. For KAUZ, one antenna (I'll call it "antenna A") will be 90 degrees ahead of the other ("antenna B"), but for KNAV, antenna A will be 90 degrees behind antenna B.

Then, you make the coax from antenna A about 4 inches longer than the coax from antenna B, then combine the signals with a common signal splitter hooked up in reverse. The extra coax delays the signal from antenna A by about 90 more degrees, so the signals from KAUZ arrive at the splitter in phase - but the signals from KNAV arrive 180 degrees out of phase, and cancel out!

To do this, you need to move one of the antennas a few inches north or south until you find the "sweet spot" that makes the cancellation work. It's a lot of effort, but if you really want to watch KAUZ, and you can't once KNAV lights up, it might be worth the trouble.

Actually, both are pointed at Cedar Hill and usually I feel the need to turn it toward Wichita Falls but is unable to find the "sweet spot" due to my TV's crappy tuner scale. 60% is the limit and is in increments of 20%. 40% and below is unreadable.

Most consumer-grade DTV receivers have lousy signal strength meters. They all share one drawback: you need a lock before you can get a measurement, but if you've got a lock, you don't really need to do much adjustment!

You might consider buying a cheap converter box just to get a somewhat better signal strength meter. The Philco converter box has the best I've seen. It goes from 100 in steps of 2 or 3 down to about 16 before you start to lose the lock. It's big drawback, other than needing a lock, is that it's very slow. It takes minutes to stabilize, then several seconds to re-stabilize after you make an adjustment.

The Philco is hard to find but the Magnavox converter box is virtually identical (the only difference is the Magnavox doesn't have analog pass-through). The Magnavox used to be sold at Wal*Mart, although converter boxes aren't as popular as they were in 2009 when the DTV transition was occurring so I don't know if it's still available there.

[eskipper411]

Glad to hear your antennas are undamaged. I'm guessing the 40-footer is pointed at Wichita Falls and the 20-footer at Cedar Hill, but feel free to correct me if I'm wrong.

F/B (front/back) ratio is simply the ratio of an antenna's gain toward the front to its gain toward the back. It's not always a useful spec, but in the KNAV vs. KAUZ case (where you're trying to tune in a signal in front of the antenna while rejecting another signal coming from behind) it gives you an idea of how strong the interfering signal can be before you have trouble. Antennas usually have negative gain toward the back; if so, the F/B ratio would be greater than the gain itself.

With digital signals, we need a minimum 15 dB signal/noise ratio to get a lock, and an interfering signal will look like noise. So if we have a reasonably strong signal in front and the antenna has a 15 dB F/B ratio, the signal from the back can be almost as strong as the signal in front before it prevents us from getting a lock.

OTOH, if the signal in front is marginal, then it'll take less signal from the back before there's too much noise to get a lock. That's why I was expecting that, in your case, KAUZ wouldn't interfere too badly with KNAV (assuming KNAV actually broadcasts something worth watching someday), but KNAV would probably interfere with KAUZ.

Finally, let me clarify about using two antennas to "null out" an interfering signal. This is easiest if the two antennas are identical and at the same height, so they both receive equally strong signals. The idea would be to point both antennas toward the signal you want (let's say KAUZ) but arrange them so the signal reaches one antenna a little bit sooner than it reaches the other. Ideally, you want the signals 90 degrees out of phase. For KAUZ, one antenna (I'll call it "antenna A") will be 90 degrees ahead of the other ("antenna B"), but for KNAV, antenna A will be 90 degrees behind antenna B.

Then, you make the coax from antenna A about 4 inches longer than the coax from antenna B, then combine the signals with a common signal splitter hooked up in reverse. The extra coax delays the signal from antenna A by about 90 more degrees, so the signals from KAUZ arrive at the splitter in phase - but the signals from KNAV arrive 180 degrees out of phase, and cancel out!

To do this, you need to move one of the antennas a few inches north or south until you find the "sweet spot" that makes the cancellation work. It's a lot of effort, but if you really want to watch KAUZ, and you can't once KNAV lights up, it might be worth the trouble.

Actually, both are pointed at Cedar Hill and usually I feel the need to turn it toward Wichita Falls but is unable to find the "sweet spot" due to my TV's crappy tuner scale. 60% is the limit and is in increments of 20%. 40% and below is unreadable.

Most consumer-grade DTV receivers have lousy signal strength meters. They all share one drawback: you need a lock before you can get a measurement, but if you've got a lock, you don't really need to do much adjustment!

You might consider buying a cheap converter box just to get a somewhat better signal strength meter. The Philco converter box has the best I've seen. It goes from 100 in steps of 2 or 3 down to about 16 before you start to lose the lock. It's big drawback, other than needing a lock, is that it's very slow. It takes minutes to stabilize, then several seconds to re-stabilize after you make an adjustment.

The Philco is hard to find but the Magnavox converter box is virtually identical (the only difference is the Magnavox doesn't have analog pass-through). The Magnavox used to be sold at Wal*Mart, although converter boxes aren't as popular as they were in 2009 when the DTV transition was occurring so I don't know if it's still available there.

I have the Digital Stream box which I barely use since I got a flat screen which is 5 years old and needs to be replaced. When I turned the antenna toward Wichita Falls with the DTX-9950, I got a steady signal near 38 on KAUZ and 30 for KFDX. Usually much stronger at 94 during tropo enhancement.

[JHBrandt]

Actually, both are pointed at Cedar Hill and usually I feel the need to turn it toward Wichita Falls but is unable to find the "sweet spot" due to my TV's crappy tuner scale. 60% is the limit and is in increments of 20%. 40% and below is unreadable.

Most consumer-grade DTV receivers have lousy signal strength meters. They all share one drawback: you need a lock before you can get a measurement, but if you've got a lock, you don't really need to do much adjustment!

You might consider buying a cheap converter box just to get a somewhat better signal strength meter. The Philco converter box has the best I've seen. It goes from 100 in steps of 2 or 3 down to about 16 before you start to lose the lock. It's big drawback, other than needing a lock, is that it's very slow. It takes minutes to stabilize, then several seconds to re-stabilize after you make an adjustment.

The Philco is hard to find but the Magnavox converter box is virtually identical (the only difference is the Magnavox doesn't have analog pass-through). The Magnavox used to be sold at Wal*Mart, although converter boxes aren't as popular as they were in 2009 when the DTV transition was occurring so I don't know if it's still available there.

I have the Digital Stream box which I barely use since I got a flat screen which is 5 years old and needs to be replaced. When I turned the antenna toward Wichita Falls with the DTX-9950, I got a steady signal near 38 on KAUZ and 30 for KFDX. Usually much stronger at 94 during tropo enhancement.

I've heard of the Digital Stream boxes but I don't have one myself. I assume 100 is the top of the scale, but how low can you go on signal strength and still get a lock?

[eskipper411]

Actually, both are pointed at Cedar Hill and usually I feel the need to turn it toward Wichita Falls but is unable to find the "sweet spot" due to my TV's crappy tuner scale. 60% is the limit and is in increments of 20%. 40% and below is unreadable.

Most consumer-grade DTV receivers have lousy signal strength meters. They all share one drawback: you need a lock before you can get a measurement, but if you've got a lock, you don't really need to do much adjustment!

You might consider buying a cheap converter box just to get a somewhat better signal strength meter. The Philco converter box has the best I've seen. It goes from 100 in steps of 2 or 3 down to about 16 before you start to lose the lock. It's big drawback, other than needing a lock, is that it's very slow. It takes minutes to stabilize, then several seconds to re-stabilize after you make an adjustment.

The Philco is hard to find but the Magnavox converter box is virtually identical (the only difference is the Magnavox doesn't have analog pass-through). The Magnavox used to be sold at Wal*Mart, although converter boxes aren't as popular as they were in 2009 when the DTV transition was occurring so I don't know if it's still available there.

I have the Digital Stream box which I barely use since I got a flat screen which is 5 years old and needs to be replaced. When I turned the antenna toward Wichita Falls with the DTX-9950, I got a steady signal near 38 on KAUZ and 30 for KFDX. Usually much stronger at 94 during tropo enhancement.

I've heard of the Digital Stream boxes but I don't have one myself. I assume 100 is the top of the scale, but how low can you go on signal strength and still get a lock?

I seen it go as low as 25 and still get a perfect lock.