Antenna rotator question

Customer wants a complete TV antenna with a rotor installed. I used
to do a lot of these so that's no problem. However the catch is that
depending on where they feel like hanging out he wants to control the
rotor from two different levels of the house. I've never tried to do
this before. Someone else suggested that I install a control wire to the two locations and have them move the rotor between the two. I know that channel Master makes a unit with an IR remote but I would need an RF based remote to go between floors. And I'm not a big fan of Channel Master anyway. Are there any RF based solutions for this? And is the equipment consumer or commercial grade?

Also back in the day I used to install Alliance rotors exclusively.
They were a real quality product and I never got married to one of
them. I know that Alliance has been gone for awhile now but is it true
that the only ones that are now available are the crappy Chinese
Philips rotors with the plastic gears that break in a windstorm? Is
it even possible to buy a good quality rotor, (besides a really
expensive Ham job) anymore? Lenny

 

[Jeff Liebermann]

On Thu, 27 Apr 2017 07:12:12 -0700 (PDT), captainvideo462009@gmail.com
wrote:

Customer wants a complete TV antenna with a rotor installed. I used
to do a lot of these so that's no problem. However the catch is that
depending on where they feel like hanging out he wants to control the
rotor from two different levels of the house.

Many rotators now have IR remote controls. For example:
<https://www.channelmaster.com/TV_Antenna_Rotator_p/cm-9521a.htm>
<https://www.google.com/search?tbm=isch&q=remote+control+antenna+rotator>
Put and IR repeater between floors, buy a few spare remote controls,
and you're done.
<https://www.google.com/search?q=ir+repeater&tbm=isch>
If you want quality, you'll probably end up with a ham radio type of
rotator, for plenty more dollars.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Ron D.]

Lenny:

Contact me directly, if you want to see pics of an outdoor eve install HD-8200U that isn't going anywhere. The antenna's are larger these days.

Although I used an Eagle Aspen ROTR-100 and a bearing that both aren't available anymore, I'm really happy with the install.

I didn't quite finish the install in terms of the minor details. The Rotor has a North position and you have to decide if your going to magnetic or real north so, I'm not calibrated yet.

I put the rotor on top of a stainless split collar,so the rotor can be rotated after the fact

I used Black oxide collars for temporary aides to install the antenna. All U-bolts are stainless. The guys are non-metalic and made of Phillystran and the hardware (like turnbuckles) is mostly 316 Stainless

There are two types of gold annodizing and one is really bad.

Two things that I would do differently are: Use a fiberglass mast on the antenna side of things and powder coat a couple of the clamps on the rotor.

You MUST use anti-seize for the stainless bolts. I used a small piece of siameze RG-6 satellite wire from the antenna to inside. The Eagle Aspen controls the rotor via Coax. I chose not to put the antenna on the same coax.

The Aspen rotates like 460 degrees, so it prevents having to go all the way around at times.

There is also 99 presets. Enough for every channel.

So, that's what I have to do: Orient properly so TVfool agrees and set the presets to the channels. I want to do an an antenna combine with a single channel antenna and get a custom combiner made and installed.

An IR to RF repeater works fine. There are lots of ways to do multi IR including over Ethernet.

The "bad thing" about this rotor is that the displayed position is the "desired position", not the current position unless the motor is stopped.

But this particular unavailable rotor has an index so it will never get out of sync.

 

On Thursday, April 27, 2017 at 7:12:18 AM UTC-7, captainvi...@gmail.com wrote:

Customer wants a complete TV antenna with a rotor installed. I used
to do a lot of these so that's no problem. However the catch is that
depending on where they feel like hanging out he wants to control the
rotor from two different levels of the house. I've never tried to do
this before. Someone else suggested that I install a control wire to the two locations and have them move the rotor between the two. I know that channel Master makes a unit with an IR remote but I would need an RF based remote to go between floors. And I'm not a big fan of Channel Master anyway. Are there any RF based solutions for this? And is the equipment consumer or commercial grade?

Also back in the day I used to install Alliance rotors exclusively.
They were a real quality product and I never got married to one of
them. I know that Alliance has been gone for awhile now but is it true
that the only ones that are now available are the crappy Chinese
Philips rotors with the plastic gears that break in a windstorm? Is
it even possible to buy a good quality rotor, (besides a really
expensive Ham job) anymore? Lenny

Nobody using a DVR? Changing the antenna while in record ruins the capture. Home many locations are they trying to receive?

G²

 

[Jeff Liebermann]

On Sat, 29 Apr 2017 11:41:51 -0700 (PDT), stratus46@yahoo.com wrote:

Nobody using a DVR? Changing the antenna while in record ruins
the capture. Home many locations are they trying to receive?
G˛

Rotating or changing the antenna while receiving a program is only
required if the signal is lousy and the user is trying to improve it.
No need to rotate the antenna if the signal quality is good. If they
were recording a lousy quality signal, I would think that rotating the
antenna might improve the situation rather than ruining the capture.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Saturday, April 29, 2017 at 12:28:50 PM UTC-7, Jeff Liebermann wrote:

On Sat, 29 Apr 2017 11:41:51 -0700 (PDT), stratus46@yahoo.com wrote:

Nobody using a DVR? Changing the antenna while in record ruins
the capture. Home many locations are they trying to receive?
G²

Rotating or changing the antenna while receiving a program is only
required if the signal is lousy and the user is trying to improve it.
No need to rotate the antenna if the signal quality is good. If they
were recording a lousy quality signal, I would think that rotating the
antenna might improve the situation rather than ruining the capture.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

When I had an antenna with a rotator many years ago it was because I was about 40 miles out from 2 different cities about 140 degrees difference. For Milwaukee the antenna aimed ENE but for Madison it needed WNW. If I was attempting to record one city and forgot and changed to the other it would have ruined the recording. Of course those were the analog days. DTV is both better and worse.

My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting.

G²

 

[Jeff Liebermann]

On Mon, 1 May 2017 01:42:17 -0700 (PDT), stratus46@yahoo.com wrote:

My point was he might be able to use multiple antennas with diplexers
and get one overall feed that could be treated like the cable company
- all channels available all the time with no adjusting.
G˛

Nope. A few problems:

1. A diplexer splits the frequencies between VHF and UHF channels. If
one antenna is VHF and the other is UHF, it will work, but only if the
stations in one direction are all VHF and the other direction are UHF.
Methinks that's unlikely to happen.

2. If you replace the diplexer with a combiner/splitter, you
theoretically can get both VHF and UHF signals from both antennas at
the same time without switching. I think that's what you're
suggesting. However, that doesn't work because the same signals are
picked up by both antenna at the same time. If the signal are in
phase, then the signals combine and you get good reception. If
they're 180 degrees out of phase, you get cancellation and no signal.
However, that's an over-simplification. What really happens is that
the signal is 6 MHz wide and the phase cancellation varies with
frequency. Some of the 6 MHz wide frequency range gets added, but
other frequencies in this range get cancelled. The result is a very
rocky and erratic frequency response which makes an ugly mess of the
signal. Bad idea.

3. You can make it work with two antennas in two directions using a
coax switch. Only one antenna is connected at a time so there is no
interaction. You might need two coax cables from the mast to the TV
where the switch is located. Or, you can setup a remote antenna
switch. Or, you can setup a cross-over switch and two receivers,
where you can record on one receiver/antenna combination, while
viewing on the other.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Monday, May 1, 2017 at 8:45:45 AM UTC-7, Jeff Liebermann wrote:

On Mon, 1 May 2017 01:42:17 -0700 (PDT), stratus46@yahoo.com wrote:

My point was he might be able to use multiple antennas with diplexers
and get one overall feed that could be treated like the cable company
- all channels available all the time with no adjusting.
G²

Nope. A few problems:

1. A diplexer splits the frequencies between VHF and UHF channels. If
one antenna is VHF and the other is UHF, it will work, but only if the
stations in one direction are all VHF and the other direction are UHF.
Methinks that's unlikely to happen.

2. If you replace the diplexer with a combiner/splitter, you
theoretically can get both VHF and UHF signals from both antennas at
the same time without switching. I think that's what you're
suggesting. However, that doesn't work because the same signals are
picked up by both antenna at the same time. If the signal are in
phase, then the signals combine and you get good reception. If
they're 180 degrees out of phase, you get cancellation and no signal.
However, that's an over-simplification. What really happens is that
the signal is 6 MHz wide and the phase cancellation varies with
frequency. Some of the 6 MHz wide frequency range gets added, but
other frequencies in this range get cancelled. The result is a very
rocky and erratic frequency response which makes an ugly mess of the
signal. Bad idea.

3. You can make it work with two antennas in two directions using a
coax switch. Only one antenna is connected at a time so there is no
interaction. You might need two coax cables from the mast to the TV
where the switch is located. Or, you can setup a remote antenna
switch. Or, you can setup a cross-over switch and two receivers,
where you can record on one receiver/antenna combination, while
viewing on the other.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

It's not a diplexer but these guys claim it can be done without a rotator.

http://downloads.channelmaster.com/Sheets/JOINtenna+spec+sheet.pdf

I presume they know what they're doing.

G²

 

[Jeff Liebermann]

On Mon, 1 May 2017 20:52:04 -0700 (PDT), stratus46@yahoo.com wrote:

On Monday, May 1, 2017 at 8:45:45 AM UTC-7, Jeff Liebermann wrote:
On Mon, 1 May 2017 01:42:17 -0700 (PDT), stratus46@yahoo.com wrote:

My point was he might be able to use multiple antennas with diplexers
and get one overall feed that could be treated like the cable company
- all channels available all the time with no adjusting.
G˛

Nope. A few problems:

1. A diplexer splits the frequencies between VHF and UHF channels. If
one antenna is VHF and the other is UHF, it will work, but only if the
stations in one direction are all VHF and the other direction are UHF.
Methinks that's unlikely to happen.

2. If you replace the diplexer with a combiner/splitter, you
theoretically can get both VHF and UHF signals from both antennas at
the same time without switching. I think that's what you're
suggesting. However, that doesn't work because the same signals are
picked up by both antenna at the same time. If the signal are in
phase, then the signals combine and you get good reception. If
they're 180 degrees out of phase, you get cancellation and no signal.
However, that's an over-simplification. What really happens is that
the signal is 6 MHz wide and the phase cancellation varies with
frequency. Some of the 6 MHz wide frequency range gets added, but
other frequencies in this range get cancelled. The result is a very
rocky and erratic frequency response which makes an ugly mess of the
signal. Bad idea.

3. You can make it work with two antennas in two directions using a
coax switch. Only one antenna is connected at a time so there is no
interaction. You might need two coax cables from the mast to the TV
where the switch is located. Or, you can setup a remote antenna
switch. Or, you can setup a cross-over switch and two receivers,
where you can record on one receiver/antenna combination, while
viewing on the other.

It's not a diplexer but these guys claim it can be done without a rotator.
http://downloads.channelmaster.com/Sheets/JOINtenna+spec+sheet.pdf
I presume they know what they're doing.
G˛

Amazing. From the specs, it looks like there's a simple passive
splitter/combiner inside the box. $39 is quite a bit to pay for a $2
combiner.

When I tried the same thing, I ran into problems with antenna
interaction as I previously described. It was easy enough to
demonstrate the problem to the customer. I disconnected and
terminated one port on the combiner. The picture quality dramatically
improved. I repeated the exercise on the other port and had the same
effect with stations on the other antenna.

I also ran into one installation that had three antennas (two UHF
only, and one VHF/UHF). I again could demonstrate that it worked
better with just one antenna at a time. However, the customer did not
want to run additional coax cables to his TV, and I couldn't find an
affordable 3 or 4 port remote antenna relay. So, I built one using
magnetically latched relays. It didn't look very good at the high
channels when swept, but the FCC saved me by auctioning off the 700MHz
channels.

I suspect that a passive combiner might work if the two antennas were
isolated from each other and positioned so that the antenna side lobes
are not pointed in the direction of the "wrong" station. Looking at
typical TV antenna patterns:
<http://www.hdtvprimer.com/ANTENNAS/comparing.html>
I think it could be done if the antennas were 90 degrees from each
other.

Of course, you're welcome to verify my analysis and tests. It's easy
enough to do with a $2 combiner. I would be interested in your
results.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Taxed and Spent]

On 5/2/2017 6:36 AM, Jeff Liebermann wrote:

On Mon, 1 May 2017 20:52:04 -0700 (PDT), stratus46@yahoo.com wrote:

On Monday, May 1, 2017 at 8:45:45 AM UTC-7, Jeff Liebermann wrote:
On Mon, 1 May 2017 01:42:17 -0700 (PDT), stratus46@yahoo.com wrote:

My point was he might be able to use multiple antennas with diplexers
and get one overall feed that could be treated like the cable company
- all channels available all the time with no adjusting.
G˛

Nope. A few problems:

1. A diplexer splits the frequencies between VHF and UHF channels. If
one antenna is VHF and the other is UHF, it will work, but only if the
stations in one direction are all VHF and the other direction are UHF.
Methinks that's unlikely to happen.

2. If you replace the diplexer with a combiner/splitter, you
theoretically can get both VHF and UHF signals from both antennas at
the same time without switching. I think that's what you're
suggesting. However, that doesn't work because the same signals are
picked up by both antenna at the same time. If the signal are in
phase, then the signals combine and you get good reception. If
they're 180 degrees out of phase, you get cancellation and no signal.
However, that's an over-simplification. What really happens is that
the signal is 6 MHz wide and the phase cancellation varies with
frequency. Some of the 6 MHz wide frequency range gets added, but
other frequencies in this range get cancelled. The result is a very
rocky and erratic frequency response which makes an ugly mess of the
signal. Bad idea.

3. You can make it work with two antennas in two directions using a
coax switch. Only one antenna is connected at a time so there is no
interaction. You might need two coax cables from the mast to the TV
where the switch is located. Or, you can setup a remote antenna
switch. Or, you can setup a cross-over switch and two receivers,
where you can record on one receiver/antenna combination, while
viewing on the other.

It's not a diplexer but these guys claim it can be done without a rotator.
http://downloads.channelmaster.com/Sheets/JOINtenna+spec+sheet.pdf
I presume they know what they're doing.
G˛

Amazing. From the specs, it looks like there's a simple passive
splitter/combiner inside the box. $39 is quite a bit to pay for a $2
combiner.

it includes a bandpass filter, although apparently Channel Master wants
to keep that a secret!

from http://www.warrenelectronics.com/antennas/Jointennas.htm


The Channel Master JoinTenna is perfect for those situations when you
need to add a second antenna to pick up a broadcast station in another
direction but don't wish to use a single antenna and rotator. The
JoinTenna blocks all frequencies but the one it is tuned for,
eliminating the ghosting and reflection that can happen when you connect
two antennas together.

~~~~~~~~~~~~~~~~~~~~~~~~~~

Note: There is significant attenuation on either side of the channel the
JoinTenna is tuned for. We do not recommend using a JoinTenna if you are
trying to receive a channel adjacent to your specified channel.

 

[Jeff Liebermann]

On Tue, 2 May 2017 07:01:32 -0700, Taxed and Spent
<nospamplease@nonospam.com> wrote:

On 5/2/2017 6:36 AM, Jeff Liebermann wrote:
Amazing. From the specs, it looks like there's a simple passive
splitter/combiner inside the box. $39 is quite a bit to pay for a $2
combiner.

it includes a bandpass filter, although apparently Channel Master wants
to keep that a secret!
from http://www.warrenelectronics.com/antennas/Jointennas.htm

Thanks for the details on the device. As you've noticed, there is
much more going on behind the curtain.

Under the heading on the above page:
"(For blocking or passing a single channel)"

"JoinTennas are NON-RETURNABLE!
Limited to stock on hand - no back-orders!"

There seems to be more than one model. In the "Antenna Coupler
Typical Applications" on the right of the page, the 3 examples show
some of the part numbers to be:
Model 0578, Model 0585-2, Model 0576, and Model 0579

The multiple models, combined with the non-returnable ordering
suggests that this is a custom device, tuned to frequency. The chart
at the bottom of the page shows only a few UHF channels available.
UHF Channels Avail. Model*
17, 18, 19 0585-1
53, 54, 55, 57, 58 0585-2
which is odd as other model numbers are mentioned under "Antenna
Coupler Typical Applications". The limited channels may be only what
the dealer stocks for his local channels.

The filter must be rather wide as the warning suggests:
"Note: There is significant attenuation on either side of
the channel the JoinTenna is tuned for. We do not recommend
using a JoinTenna if you are trying to receive a channel
adjacent to your specified channel."

None of this appears on the product page, data sheet, or installation
manual:
<https://www.channelmaster.com/JOINtenna_p/cm-0500.htm>

I like the first users comments:
"Having a rotating antenna was not the solution because
with today's digital tuners, every time you rotate the
Antenna, you must rescan your channels."
I guess he doesn't know how to manually add channels.

The Channel Master JoinTenna is perfect for those situations when you
need to add a second antenna to pick up a broadcast station in another
direction but don't wish to use a single antenna and rotator. The
JoinTenna blocks all frequencies but the one it is tuned for,
eliminating the ghosting and reflection that can happen when you connect
two antennas together.

With digital TV, one does not see ghosting or reflections on the
screen. The modern term is "multipath".
<http://www.hdtvprimer.com/ANTENNAS/glossaryG.html#multipath>

<http://www.hdtvprimer.com/ANTENNAS/siting.html>
See section under "Skyline Multi-path".

If it blocks everything except the channel to which it's tuned, it
must contain a BPF (bandpass filter) which adds some loss. The -2dB
loss specified seems rather optimistic. The splitter/combiner
typically has -1dB loss. A single channel BPF would have somewhat
more than -1dB. My guess(tm) is the loss through the device is
somewhat more than -2dB. There might also be a corresponding notch
filter on the other port, also with some loss.

Seems like this device is a usable solution if:
1. One antenna is intended to only receive one distant station.
2. The signal strengths of most stations are strong to overcome the
losses.

I think it fair to suggest that Channel Master would not have gone
though all the trouble of installing filter(s) if there was no problem
with interaction between antennas using a combiner.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Clifford Heath]

On 03/05/17 02:11, Jeff Liebermann wrote:

On Tue, 2 May 2017 07:01:32 -0700, Taxed and Spent
nospamplease@nonospam.com> wrote:

On 5/2/2017 6:36 AM, Jeff Liebermann wrote:
Amazing. From the specs, it looks like there's a simple passive
splitter/combiner inside the box. $39 is quite a bit to pay for a $2
combiner.

it includes a bandpass filter, although apparently Channel Master wants
to keep that a secret!
from http://www.warrenelectronics.com/antennas/Jointennas.htm

Thanks for the details on the device. As you've noticed, there is
much more going on behind the curtain.

Under the heading on the above page:
"(For blocking or passing a single channel)"

"JoinTennas are NON-RETURNABLE!
Limited to stock on hand - no back-orders!"

There seems to be more than one model. In the "Antenna Coupler
Typical Applications" on the right of the page, the 3 examples show
some of the part numbers to be:
Model 0578, Model 0585-2, Model 0576, and Model 0579

The multiple models, combined with the non-returnable ordering
suggests that this is a custom device, tuned to frequency. The chart
at the bottom of the page shows only a few UHF channels available.
UHF Channels Avail. Model*
17, 18, 19 0585-1
53, 54, 55, 57, 58 0585-2
which is odd as other model numbers are mentioned under "Antenna
Coupler Typical Applications". The limited channels may be only what
the dealer stocks for his local channels.

The filter must be rather wide as the warning suggests:
"Note: There is significant attenuation on either side of
the channel the JoinTenna is tuned for. We do not recommend
using a JoinTenna if you are trying to receive a channel
adjacent to your specified channel."

None of this appears on the product page, data sheet, or installation
manual:
https://www.channelmaster.com/JOINtenna_p/cm-0500.htm

I like the first users comments:
"Having a rotating antenna was not the solution because
with today's digital tuners, every time you rotate the
Antenna, you must rescan your channels."
I guess he doesn't know how to manually add channels.

The Channel Master JoinTenna is perfect for those situations when you
need to add a second antenna to pick up a broadcast station in another
direction but don't wish to use a single antenna and rotator. The
JoinTenna blocks all frequencies but the one it is tuned for,
eliminating the ghosting and reflection that can happen when you connect
two antennas together.

With digital TV, one does not see ghosting or reflections on the
screen. The modern term is "multipath".
http://www.hdtvprimer.com/ANTENNAS/glossaryG.html#multipath

http://www.hdtvprimer.com/ANTENNAS/siting.html
See section under "Skyline Multi-path".

If it blocks everything except the channel to which it's tuned, it
must contain a BPF (bandpass filter) which adds some loss. The -2dB
loss specified seems rather optimistic. The splitter/combiner
typically has -1dB loss. A single channel BPF would have somewhat
more than -1dB. My guess(tm) is the loss through the device is
somewhat more than -2dB. There might also be a corresponding notch
filter on the other port, also with some loss.

Seems like this device is a usable solution if:
1. One antenna is intended to only receive one distant station.
2. The signal strengths of most stations are strong to overcome the
losses.

I think it fair to suggest that Channel Master would not have gone
though all the trouble of installing filter(s) if there was no problem
with interaction between antennas using a combiner.

It seems as though it should be straightforward to feed power
up the co-ax (ala masthead amplifiers) to drive a pair of isolation
amps/buffer before a combiner. That could give you a lot more isolation,
without needing to go to relays.

Clifford Heath.

 

[Ron D.]

I like the first users comments:
"Having a rotating antenna was not the solution because
with today's digital tuners, every time you rotate the
Antenna, you must rescan your channels."
I guess he doesn't know how to manually add channels.

That's not as far-fetched as you would think.

with current Samsung so called "Smart TV's" it's not possible to add a channel. I have confirmation from Samsung.

USUALLY you can use the remote to select the physical channel and the TV will tune to the first virtual channel on that frequency. This is the preferred way the US government would like it to work. Channel up/down will then tune the sub-channels.

I don;t yet have confirmation that an unscanned channel works that way, but I think it will.

I have a TV tuner that will not work that way at all. It reports the actual center frequency in MHz of the scanned channels, not the physical channel, but you need the physical channel to add a single channel. You basically "scan" the physical channel and add. This "stupid" $1000 tuner won;t even update the display when entering a channel digit. The on-screen display shows the remote entered digit. The display on the tuner does not.

A CECB I have allows one to add "scanned" channels to the existing scan.

 

[Ron D.]

Incidently,
The CECB reports signal strength in 0 to 100 arbitrary units.
The "Dumb" Samsung TV just reports s/n ratio
The $1000 tuner reports both s/n and signal strength in real units.

 

[Jeff Liebermann]

On Wed, 3 May 2017 07:47:12 +1000, Clifford Heath <no.spam@please.net>
wrote:

It seems as though it should be straightforward to feed power
up the co-ax (ala masthead amplifiers) to drive a pair of isolation
amps/buffer before a combiner. That could give you a lot more isolation,
without needing to go to relays.

Clifford Heath.

Nope. The lack of isolation is NOT in the combiner. Assuming a
reasonable 75 ohm termination on all ports, a good combiner can
deliver 20 to 50dB isolation over the VHF-UHF TV band. I could
replace the splitter/combiner with a 6dB resistive power
divider/combiner, which has 6dB of isolation, and get the same
problems at a 3dB lower signal level.
Resistive power divider/combiner:
<https://www.microwaves101.com/encyclopedias/resistive-power-splitters>
A proper splitter:
<http://802.11junk.com/jeffl/crud/CATV-splitter.png>
Good splitter/combiner and total crap splitter/combiner:
<http://802.11junk.com/jeffl/crud/CATV-splitters.jpg>

Anyway, the problem is the isolation between antennas. If both
antennas can pickup the same signal, from the same station, the
signals are going to add or cancel depending on the phase and
amplitude. If there is a phase delay between these two signals, they
will act much exactly as if there was a multipath problem. ATSC 8-VSB
has some limited protection against multipath, but I wouldn't count on
it. The symptoms manifest themselves as everything that could
possibly trash a DTV signal. Fluttering, Stuttering, freezing,
pixellation, rainbow color light shows, signal loss, etc. As I
mentioned in a previous rant, the degree of cancellation and
impairment is frequency dependent, which means I can't easily use a
simple phase shifter to remedy the situation. I found some reference
which suggested that one can see ghosts on a DTV with multipath. I
never saw it or if they were there, they were buried under the light
show and pixellation.

Someone is sure to ask why then do two stacked antennas work?
<https://www.google.com/search?q=tv+antenna+stacking&tbm=isch>
These work because both antennas involved are looking at the same
station, which produces the same signal level at the same phase at
each antenna. Therefore, they can safely be combined, where the two
signals add in phase, and therefore produce 3dB more effective anenna
gain.

Incidentally, I originally started by building a DPST PIN diode switch
which selected which antenna was active by which coax cable had DC
supplied to it. However, I made a stupid mistake and couldn't get it
to function correctly. Since I was burning time and loosing money on
this particular customer, so I took the easy way out and used a pair
of spare latching relays and two push buttons from an HF antenna tuner
project.

Bottom line: RF is magic.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Tue, 2 May 2017 15:22:23 -0700 (PDT), "Ron D."
<ron.dozier@gmail.com> wrote:

I like the first users comments:
"Having a rotating antenna was not the solution because
with today's digital tuners, every time you rotate the
Antenna, you must rescan your channels."
I guess he doesn't know how to manually add channels.

with current Samsung so called "Smart TV's" it's not
possible to add a channel. I have confirmation from Samsung.

Sigh. I've been told to avoid anything called amazing, magic,
miracle, plus, super, and such. I guess I now have to add smart to
the banned list.

I just checked a Visio VX240M TV:
<http://802.11junk.com/jeffl/crud/Visio%20Channel%20Skip.jpg>
It starts out by skipping all channels and sub-channels. You can then
go down the shopping list of channels and select which ones to NOT
skip. Kinda backwards, but easy enough. The TV also has a "limited
scan" which allows the user to set channel areas to re-scan complete
with limiting the scan to digital, analog, or both.

I have a Samsung TV at home. I'll see what it can do later tonite.
-

USUALLY you can use the remote to select the physical channel and
the TV will tune to the first virtual channel on that frequency.
This is the preferred way the US government would like it to work.
Channel up/down will then tune the sub-channels.

I don;t yet have confirmation that an unscanned channel works
that way, but I think it will.

I have a TV tuner that will not work that way at all. It reports
the actual center frequency in MHz of the scanned channels, not
the physical channel, but you need the physical channel to add
a single channel. You basically "scan" the physical channel and
add. This "stupid" $1000 tuner won;t even update the display
when entering a channel digit. The on-screen display shows the
remote entered digit. The display on the tuner does not.

A CECB I have allows one to add "scanned" channels to the
existing scan.

Nice mess. In the daze of analog TV VSB (vestigial sideband), the
frequency of a TV channel was by the carrier frequency. This worked
because the signal was asymmetrical. Symmetrical modulation schemes,
such as FM, used the center frequency. SSB continued to use the
carrier frequency. Meanwhile, the FCC uses the center frequency for
most everything. Along came DTV, without a carrier frequency, so it
was decided to use the center frequency. That generally satisfied the
tech types.

However, the station owners wanted to retain their old channel
designators, even if the channel frequency was quite different. This
was allegedly to avoid listener confusion, but did quite the opposite.
I was told that it was temporary, but that doesn't seem to be
happening. The best laid plans...

One way to avoid having to deal with two sets of channel numbers would
be to replace the real OTA channel number with that channels center
frequency. That's apparently what was done in your expensive tuner.
Whether the GUM (great unwashed masses) could handle the concept is
debatable. They certainly are having problems with todays virtual
channel system.

Another proposal that came and went was to replace the virtual
channels with the stations call letters. This probably would have
worked with an internet connected TV that could search a suitable
database. However, the present system was thrown together before most
everyone had internet available, so that went nowhere.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Tue, 2 May 2017 15:31:40 -0700 (PDT), "Ron D."
<ron.dozier@gmail.com> wrote:

Incidently,
The CECB reports signal strength in 0 to 100 arbitrary units.
The "Dumb" Samsung TV just reports s/n ratio
The $1000 tuner reports both s/n and signal strength in real units.

The 0 to 100 is not quite arbitrary. It starts out as an 8 bit number
(0 to 255) from the receiver demodulator. That gets fed to a
microprocessor, which converts it to 0 to 100. That's because most
users do not count in binary or hex, and must therefore be supplied
with their numbers in decimal format. Seems rational. In cellular
handsets, there is a conversion algorithm or lookup table that relates
actual signal strength at the receiver input to the 0 to 100 numbers.

There is also a conversion to the number of bars (usually 5 bars),
which are totally at the discretion of the handset manufacturer.
That's what got Apple in trouble when they initially provided a
linearized conversion from RSSI to bars and discovered that it made
the iPhone 4 looks bad when the user grabbed the antenna.

Ok, back to the TV. The SNR (signal to noise ratio) in not the usual
analog style:
(signal + noise + distortion) / (noise + distortion)
Instead it's based on the BER (bit error rate) or MER (modulation
error rate). Basically, it's a measure of how many errors the receive
has to deal with in order to display a decent picture. The more
errors that need correction, the lower the SNR. I believe that
there's yet another lookup table correlating the BER to what the SNR
would be if it were an analog receiver, but I'm not sure that this is
really true.
<http://blog.solidsignal.com/content.php/2768-DTV-Antenna-Help-and-a-touch-of-SNR-BER-MER>

What I wanna see is Eb/N0 (energy per bit to noise power spectral
density ratio):
<https://en.wikipedia.org/wiki/Eb/N0>
This for European DVB, but the theory is about the same for US DTV:
"Bit Error Ratio BER in DVB as a Function of S/N"
<https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/7bm03/7BM03_4E.pdf>




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Clifford Heath]

On 03/05/17 10:28, Jeff Liebermann wrote:

On Wed, 3 May 2017 07:47:12 +1000, Clifford Heath <no.spam@please.net
wrote:

It seems as though it should be straightforward to feed power
up the co-ax (ala masthead amplifiers) to drive a pair of isolation
amps/buffer before a combiner. That could give you a lot more isolation,
without needing to go to relays.

Clifford Heath.

Nope. The lack of isolation is NOT in the combiner. Assuming a
reasonable 75 ohm termination on all ports, a good combiner can
deliver 20 to 50dB isolation over the VHF-UHF TV band. I could
replace the splitter/combiner with a 6dB resistive power
divider/combiner, which has 6dB of isolation, and get the same
problems at a 3dB lower signal level.
Resistive power divider/combiner:
https://www.microwaves101.com/encyclopedias/resistive-power-splitters
A proper splitter:
http://802.11junk.com/jeffl/crud/CATV-splitter.png
Good splitter/combiner and total crap splitter/combiner:
http://802.11junk.com/jeffl/crud/CATV-splitters.jpg

Anyway, the problem is the isolation between antennas. If both
antennas can pickup the same signal, from the same station, the
signals are going to add or cancel depending on the phase and
amplitude. If there is a phase delay between these two signals, they
will act much exactly as if there was a multipath problem. ATSC 8-VSB
has some limited protection against multipath, but I wouldn't count on
it. The symptoms manifest themselves as everything that could
possibly trash a DTV signal. Fluttering, Stuttering, freezing,
pixellation, rainbow color light shows, signal loss, etc. As I
mentioned in a previous rant, the degree of cancellation and
impairment is frequency dependent, which means I can't easily use a
simple phase shifter to remedy the situation. I found some reference
which suggested that one can see ghosts on a DTV with multipath. I
never saw it or if they were there, they were buried under the light
show and pixellation.

Someone is sure to ask why then do two stacked antennas work?
https://www.google.com/search?q=tv+antenna+stacking&tbm=isch
These work because both antennas involved are looking at the same
station, which produces the same signal level at the same phase at
each antenna. Therefore, they can safely be combined, where the two
signals add in phase, and therefore produce 3dB more effective anenna
gain.

Incidentally, I originally started by building a DPST PIN diode switch
which selected which antenna was active by which coax cable had DC
supplied to it. However, I made a stupid mistake and couldn't get it
to function correctly. Since I was burning time and loosing money on
this particular customer, so I took the easy way out and used a pair
of spare latching relays and two push buttons from an HF antenna tuner
project.

Bottom line: RF is magic.

Ok, well in that case, just use an imposed DC level (+ve or -ve)
to enable one of two switch diodes. Whichever diode is forward
biassed passes that antenna's signal. Simpler and cheaper than
relays.

Clifford Heath.

 

[Jeff Liebermann]

On Wed, 3 May 2017 12:26:15 +1000, Clifford Heath <no.spam@please.net>
wrote:

Ok, well in that case, just use an imposed DC level (+ve or -ve)
to enable one of two switch diodes. Whichever diode is forward
biassed passes that antenna's signal. Simpler and cheaper than
relays.
Clifford Heath.

I used 4 PIN diodes. I had a bag of Motorola MPN3401 diodes handy.
<http://images.ihscontent.net/vipimages/VipMasterIC/IC/FSCL/FSCLS06284/FSCLS06284-1.pdf>
As you suggested, I used a bipolar switching arrangment. On each
antenna, a pass diode would conduct the signal from the antenna to the
receiver, while the other diode was reverse biased and effectively
disconnected. At the same time, the other antenna did the opposite.
The pass diode was reverse biased off, while the other diode would
short the antenna to ground. Something close to this, but with
bipolar power arrangement:
<http://www.analog.com/-/media/images/analog-dialogue/en/volume-44/number-1/articles/driving-pin-diodes-with-op-amps/pin_diode-fig-05.jpg?la=en>

However, it didn't work. I wasn't interested in climbing the roof,
dropping the mast, and dragging a pile of test equipment to the roof
for troubleshooting the problem. So, I just built a relay
replacement, which didn't sweep so good on the bench, but worked well
enough when installed. There were various reasons for this approach.
I vaguely recall that I was scheduled to go sailing the next day or
something similar.

Thinking about the problem, my guess(tm) is that either I used the
wrong ferrite beads and/or chokes to isolate the PIN diodes from the
applied DC, or I used the wrong value coupling caps. I also made the
capital mistake of not sweeping the circuit before attempting to
install it. It was such a simple circuit. What could possibly go
wrong? Anyway, if I had to do it again, I would use the same approach
with the possible addition of FM and cellular RF notch filters.




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Ron D.]

Nice mess. In the daze of analog TV VSB (vestigial sideband), the
frequency of a TV channel was by the carrier frequency. This worked
because the signal was asymmetrical. Symmetrical modulation schemes,
such as FM, used the center frequency. SSB continued to use the
carrier frequency. Meanwhile, the FCC uses the center frequency for
most everything. Along came DTV, without a carrier frequency, so it
was decided to use the center frequency. That generally satisfied the
tech types.

I totally agree. I do have equipment that can measure BER and signal strength, but it was an early adopter sort of thing and not convenient to use.

So, rotators are really foreign to Samsung.

That tuner is just plain weird because I need the physical channel re-scan for virtual channels and it only reports the center frequency. In the ATSC specs there is a center frequency field and sometimes it's wrong.

The $1000 tuner can;t do Daylight Savings Time properly, nor can it do the EPG properly. Incidentally, this http://auroramultimedia.com/products/vtune-pro-4k/ is the high end tuner. It has other quirks too.

I think a big issue for them is cable cards fell out of favor or don't exist anymore.

It's grand scheme of things is to put the output on an IPTV/RF modulator so I can watch on my laptop. I just haven't got there yet.

As another ASIDE (sorry), I want a way to take analog L/R and upconvert to AC3 5.1 in a "Audio Only" TV mode over HDMI, so I can put an AM/FM tuner on an ATSC channel.