What happened to DTV channel 7 to 13 ?

[DVWannaB]

I am picking up those channels without any fuss, except I dont get channel 8 either. There is some issue with them going full power and getting licencing permission, blah blah. Same with Telemundo ch.25. I saw a discussion yesterday on AVS Forum, which was kinda confusing, but most people are not picking up ch. 8, 14, 25 and 47.

Its weird, the CM4228 picks up 4.1, 5.1, 9.1, 20.1 with no breakups or problems. 7.1 is somewhat fussy about, with break-up picure from time to time. On the other hand the Antennas direct DB-4, pick up 4.1, 5.1, 7.1, 20.1 no problems.

[DarrellS]

WinTV's Digital Signal Monitor shows all of my channels with a Signal to Noise ratio of at least 24 except for PBS and NBC which show 15 to 20 SNR. The signal works fine above 17 but is choppy when drops below that. FOX 10 shows no SNR at all.

Hopefully after August 30th (when FOX is supposed to have their antennas fully operational) I'll be able to get FOX 10 also.

Found a thread on another forum where one guy accused another poster of being the only person to have trouble with FOX 10 in Phoenix but every single poster I've seen from the Phoenix area is having trouble with FOX channel 10. It's the only channel that won't come in. Experts say the reason is because it's VHF but the other VHF channels come in fine.

The guy then went on to state that the reason that FOX might not come in is because they are only broadcasting at 20kw while KAET channel 8 and KPNX channel 12 are both running at 40kw. No wonder FOX isn't coming in if it's broadcasting at half the power.

He also stated that FOX is supposed to broadcast at 56kw after their completion at the end of August.

[SingSing]

I am not getting my local channel 7, instead I am getting out of state channel 10 broadcast. Go figure.

Note: I assume channel 10 is at higher VHF band than channel 7.

[edDV]

I am not getting my local channel 7, instead I am getting out of state channel 10 broadcast. Go figure.

Note: I assume channel 10 is at higher VHF band than channel 7.

Virtual channel or real RF channel? How do you know it is channel 7 or channel 10?

Channel 7 and 10 are both in the upper VHF band (174 - 216 Mhz).

[SingSing]

Made the coat hanger DTV antenna, and the result is WOW !

[DarrellS]

This one didn't work at all.

[SingSing]

This one didn't work at all.

Sorry, to hear that.

I believe the coat hanger antenna is extendable to get higher gain, like this :

[freebird73717]

You might also consider adding a metal reflector screen about 4 1/2 inches behind the coat hangers. You'll be amazed how much better signal strength you get with a reflector screen.

[SingSing]

You might also consider adding a metal reflector screen about 4 1/2 inches behind the coat hangers. You'll be amazed how much better signal strength you get with a reflector screen.

Waht happened if the screen is attached behind (just on the other side of) the wooden bar ?

[freebird73717]

It needs to be at 4 to 4 1/2 inches to work properly and get the best reception.

I'm sure there is a more technical answer involving phasing and other fancy words but I can't give it to you. I just know that every thing I've read on building a uhf antenna like that says that it needs to be about 4 inches behing the coat hangers.

[DarrellS]

If anyone is using a TV tuner card, the software used can affect the signal you receive. I Upgraded from WinTV 6 to WinTv 7 and lost channels 5 through 12. I tried a couple of trials a month ago of Sage TV and BeYound TV and I wasn't happy with either one. One of them (I don't remember which) would try to get FOX 15 but I didn't like the user interface and a few channels didn't have as strong a signal. The other wasn't even as good as the free WinTV 6. Others may have better luck but I just can't see spending all this money to get free TV.

[DarrellS]

You might also consider adding a metal reflector screen about 4 1/2 inches behind the coat hangers. You'll be amazed how much better signal strength you get with a reflector screen.

Waht happened if the screen is attached behind (just on the other side of) the wooden bar ?

I tried aluminum backing but only had it at 2" and The signal dropped significally. I would like to try the metal screen idea though. All our screens are nylon.

This one didn't work at all.

Sorry, to hear that.

I believe the coat hanger antenna is extendable to get higher gain, like this :

Do you add an extra crossover or just extent it. I thought about trying this but got frustrated and gave up after the last antenna I built.

[SingSing]

I tested this Hanger DTV antenna yesterday. It works great on the second floor, but did not do better against an amplified philips antenna on the first floor.

An rigid aluminum foil deflector did not improved the antenna gain, at any distance. Perhaps the type of reflector does matter.

About extending the antenna, I am thinking about doing this for electrical setup:



Note: This indeed look very Jetson !

[SingSing]

This one didn't work at all.

on the design you are working on, those long wires behind are type of reflector.

I did not exactly use coat hanger! I used 16AWG wire. I also use washer, see below. Those are what made the good connections needed for making antenna, which is dealing with micro or nano V of signal.

[freebird73717]

An rigid aluminum foil deflector did not improved the antenna gain, at any distance. Perhaps the type of reflector does matter.

I used a rigid metal wire mesh I had stashed away. Don't even remember where it came from. I've also seen people use chicken wire that you can get from most hardware stores. I've even seen people use metal cookie cooling racks.

[Nelson37]

I, too, have lost local channel 11 in my area. It was always one of the most sensitive to antenna orientation but I was able to receive it with both the Phillips MANT-10 and the amplified TERK. Area code 33914.

One thing which struck me while testing various antennas was the range and difference of results. VHF seems to be the weak link.

Are there similar homemade designs for VHF antennas, and more importantly, how would one go about combining reception of two specialized antennas, one UHF + weak VHF and a strong VHF receiver, assuming one can be found?

[SingSing]

The big advanatge on Digital TV antenna, is that you can parallel ( add or combine ) multiple antenna, and not worried about ghost image, which is an Analog TV only issue.

So, We should able to add a bunch of home made VHF and UHF DTV antenna, so we can even eliminating the need to point the antenna, at different stations.

Sooner or later the back of my large screen Tv, will look like an antenna farm.

[edDV]

I, too, have lost local channel 11 in my area. It was always one of the most sensitive to antenna orientation but I was able to receive it with both the Phillips MANT-10 and the amplified TERK. Area code 33914.

One thing which struck me while testing various antennas was the range and difference of results. VHF seems to be the weak link.

Are there similar homemade designs for VHF antennas, and more importantly, how would one go about combining reception of two specialized antennas, one UHF + weak VHF and a strong VHF receiver, assuming one can be found?

You must be using UHF only antennas.

According to TVFool.com, your virtual CBS 11.1 is really transmitting on 9. This should be your second strongest station but you should confirm this by entering your full address. CBS on 9 is your only close VHF station. The rest are UHF.

You can use a combiner (passive or active) to add a VHF antenna. In your zip a simple dipole (rabbit ears) should work. You have very strong local signals. Tampa would be difficult. >90 miles and two hills blocking.

[edDV]

The big advanatge on Digital TV antenna, is that you can parallel ( add or combine ) multiple antenna, and not worried about ghost image, which is an Analog TV only issue.

So, We should able to add a bunch of home made VHF and UHF DTV antenna, so we can even eliminating the need to point the antenna, at different stations.

This would only work in a local strong signal environment. If you are in the fringe, or mixing strong with weak signals, the S/N issues require level matching at the combiner to manage the noise floor.

[tomlee59]

The big advanatge on Digital TV antenna, is that you can parallel ( add or combine ) multiple antenna, and not worried about ghost image, which is an Analog TV only issue.

So, We should able to add a bunch of home made VHF and UHF DTV antenna, so we can even eliminating the need to point the antenna, at different stations.

Yes, you no longer worry about ghosting, but you still must worry about creating nulls. You can't arbitrarily combine two waves, and expect that the sum will always be bigger. If they're 180 degrees out of phase, addition can result in zero output.

The word "digital" confuses people. The waves are still very much analog. Only the information that they're carrying happens to be encoded in digital form. The waves continue to obey the laws of analog.

[SingSing]

You have to agreed it is next to impossible to have two multiple element antennas to be place in 180 degree position and cause a null.

In wireless digital signal decoding, the decoder is looking for the stream of bits, and not phase or frequnency or amplitude relationship used by analog decoder that see the imperfection of mutiple copies of the TV signal.

[edDV]

In wireless digital signal decoding, the decoder is looking for the stream of bits, and not phase or frequnency or amplitude relationship used by analog decoder that see the imperfection of mutiple copies of the TV signal.

Not so easy. The RF path is all analog and subject to multi-path phase distortion. This is why directional antennas improve reception by minimizing multi-path interference in strong signal environments. The tuner issues are all analog until after the channel is tuned and frequency shifted to the baseband IF frequency. Up to this point, DTV is very similar to AM radio or analog TV and is subject to the same RF physics.

Even ATSC demodulation is largely an analog process until the digital stream is separated.

Here is a good description of how ATSC 8-VSB works.
Read the "AM Modulation" to "8-VSB EYE DIAGRAM" sub-topics.
http://user.chol.com/~dtvkorea/kdtv8vsb.htm

[Nelson37]

By "combiner", do you mean a simple coax splitter, or is this something more complex?

"level matching at the combiner". I know what all the words mean, but how exactly would one go about doing this?

If I understand correctly, I am in a strong signal environment which would make this simpler. Haven't re-tested my older antennas since the second changeover, one had an additional coax input which seemed to work with a secondary rabbit-ear antenna.

The Philipps antenna has rabbit-ears, which had to be very carefully positioned to receive 11 previously. It is mounted about 10-feet up on a shelf. The Terk in the other room is now about 8-feet hi after using a corrugated space-frame module to increase the vertical component.

Yes, I put it on top of a cardboard box.

My interest in two antennas combined results from adjusting to receive 11 and losing 30.1, .2, .3, and .4, then going the other way around, multiple times. With the adjustment requiring a ladder and the remote non-functional from there, this got real tedious.

When using a pole-mounted outdoor antenna, what precautions are required in areas of intense lightning activity?

[tomlee59]

You have to agreed it is next to impossible to have two multiple element antennas to be place in 180 degree position and cause a null.

In wireless digital signal decoding, the decoder is looking for the stream of bits, and not phase or frequnency or amplitude relationship used by analog decoder that see the imperfection of mutiple copies of the TV signal.

No, I do not. Ghosting actually tells you all you need to know. If your reasoning were correct, then ghosting would not afflict analog channels. A reflection strong enough to ghost is strong enough to null.

It's ok that you're not a wireless expert -- most people are not -- but perhaps it's better not to make so many bold assertions until you know a bit more about the field. In the meantime, some facts to ponder: Light takes one nanosecond to go about a foot in free space. A 500MHz carrier has a half-period of 1nanosecond. The consequences of these numbers for "randomly combining antenna elements" should be self-evident.

[SingSing]

I happened to work at a place that consider 1 GHz and below is considered as DC.
500 MHz signal can be directly digitally decoded with Ultra Wide Band.

Note: We don't use stick antenna much because they can't be flown at the speed of thousands of miles per hour.

[tomlee59]

Wonderful -- then presumably you have colleagues who can recommend good texts and papers to read about the subject. My personal favorites are the classic papers by Donald Cox and his associates at Bell Labs, dating back to the 70s, for information about wireless systems in general, and in particular about the vagaries of wireless propagation (which is the heart of the matter here). For antenna design specifically, there's the classic text by John Kraus (inventor of the helical antenna), and a highly accessible recent presentation by Stutzman and Thiele.

The free-space speed of light is pretty independent of frequency, so whether 500MHz is "DC" and can be decoded "with UWB" is quite beside the point. UWB systems suffer less from multipath effects because the "Murphy" condition of cancellation is a narrowband phenomenon, and therefore less likely to wipe out a large swath of spectrum. UWB suffers from other severe problems, however, which has greatly limited its utility to a much tinier niche than proponents had originally hoped. But that's a topic for another day, and a different forum.

And as for stick antennas having poor aerodynamics, all one can say is "sure," but what that has to do with this thread is mysterious to me.

[edDV]

By "combiner", do you mean a simple coax splitter, or is this something more complex?

"level matching at the combiner". I know what all the words mean, but how exactly would one go about doing this?

If I understand correctly, I am in a strong signal environment which would make this simpler. Haven't re-tested my older antennas since the second changeover, one had an additional coax input which seemed to work with a secondary rabbit-ear antenna.

The Philipps antenna has rabbit-ears, which had to be very carefully positioned to receive 11 previously. It is mounted about 10-feet up on a shelf. The Terk in the other room is now about 8-feet hi after using a corrugated space-frame module to increase the vertical component.

Yes, I put it on top of a cardboard box.

In a strong signal area you can use a splitter in the reverse direction but you are cutting signal strength in half from both antennas. Active combiners allow variable amplification from multiple antenna inputs. These work best when near the antenna (e.g. in an attic).

In urban areas amplification often creates more problems than it solves. Amplification raises the noise floor, the desired signal and all multi-path reflections. Directional antennas raise the desired signal and reduce multi-path.

My interest in two antennas combined results from adjusting to receive 11 and losing 30.1, .2, .3, and .4, then going the other way around, multiple times. With the adjustment requiring a ladder and the remote non-functional from there, this got real tedious.

If all transmitters are on the same LOS (line of sight) mountain peak, then a directional UHF/VHF antenna works fine. If stations or reflections of stations are coming from different directions, then you need to use separate antennas. FRS radios (walkie talkie) work great when pointing antennas. If you are only receiving a reflection, expect this the change with weather conditions. First try to get the direct signal by pointing at the transmitter.

First thing I would do in your situation is disconnect everything except a rabbit ears and see if you can get a stable Channel 9 (Virtual 11.1). If so then a combiner should work.

When using a pole-mounted outdoor antenna, what precautions are required in areas of intense lightning activity?

These should be properly grounded. Just google TV antennas and lightening.

[edDV]

I happened to work at a place that consider 1 GHz and below is considered as DC.
500 MHz signal can be directly digitally decoded with Ultra Wide Band.

Ummm??? So you are saying microwaves behave differently than UHF/VHF? Is this news?

Microwaves require LOS and don't even get a dead cat bounce. Unless you can increase power to government waste levels.

[SingSing]

High band Microwave is nearly all line of sight. RF is not.

With Phase Array Technique, that's how present day multi-mega watts transmitters are built.
The power of hundreds of solid state PA, get combined, and steered by phase differences.
There are a lot of these out there.

I am quite sure, we are off topics.

DTV is fun. Microwave is not.

[SingSing]

Channel 7 came back ! Look like they got approval to crank it up.