On Apr 28, 9:19*pm, tom wrote:
On 4/28/2010 6:48 PM, Art Unwin wrote:



On Apr 28, 3:42 pm, *wrote:
On Apr 28, 3:59 pm, Art *wrote:

On Apr 28, 1:53 pm, Michael *wrote:

Jeff Liebermann wrote:
A link to the Wikipedia page would probably have been sufficient:
http://en.wikipedia.org/wiki/Diversity_scheme
The problem is that NONE of the diversity schemes mentioned in the
Wikipedia article apply to the single antenna example under
discussion. *In my never humble opinion, there's no way to provide any
form of diversity reception improvement with a single antenna, unless
one also has two feeds, going to two different receivers, and ending
in either a decision switch, or some form of intelligent combiner.

Trying to wrap my mind around this...

I wouldn't know how splitting the signal to two receivers would work..
The issue arises at the antenna doesn't it?

Indeed, if a single wire antenna would work for diversity reception,
wouldn't it then follow that you would not have to use diversity
reception? The signal would already be there for you.

Seems like a simple test could answer this one.

* * * * *- 73 de Mike N3LI -

I think the first place to start is to what the actual antenna pattern
represents in terms of polarity.
For instance, we have two vectors outside the earths boundary thus you
must have two vectors inside the arbitrary *boundary. Obviously the
gravity vector will be at right angles to the earths surface. The
other vector representing the rotation of the earth will naturally be
an circular pattern which is the "saucer" pattern portion of the
overall pattern, which is what hams mainly use. Thus we have to make
the first determination as being what each portion of the pattern
represents in terms of polarity, the centre being straight plume field
and the bottom circular field which is a rotational vector. Since they
are in vector form we can see them as a stream of particles where the
two vectors will be additive. It is only then that the problem of
different or the same phase factors *can be ascertained. Definitions
applied can be approach later. Personally, I view the gravity vector
as linear with the other providing a wobberly helical vector i.e
circular. but varying angles to the earths surface. Other thinkers
will surely disagree, if only to fight over near field over far field!

I have no doubt that gravity effects radio waves in the same manner
that it has been proven to effect light. The effects are going to be
such that unless your signal is passing by a black hole of no
practical concern.

Have a great day Art.

Jimmie

Totally wrong!
The vector inside the boundary opposes gravity!
The particle has a straight line trajectory and does not fall back to
earth during that trajectory.The rotary vector supplies spin to the
other vector force
just as the dimples in an golf ball or the rifling of a firearm
barrel. These same vectors are represented
by time varying electrical current (straight line) as well as
displacement current which generates a vortex by its circular motion.
When the current flow is completely outside the surface of the
radiator skin depth disappears as does resistance. So the radiator has
a skin of tightly bonded particles upon which the straight line
trajectory is imposed. Remember, earth gravity has zero effect on
propagation inside a arbitrary boundary otherwise straight line
projection could not exist.

Welcome back, Art!

And I'm quite serious.

Obviously you are no longer taking your medications or maybe they just
let you out.

Please keep it up. *I, for one, have missed your lack of connection to
reality. *It is very amusing.

tom
K0TAR

Perception is not the same as reality. A mixer in a radio is different
than what is required when seeking diversity. The first is the mixing
of two different frequencies where diversity requires the mixing of
two frequencies of the same except one has a delay. The output of the
latter is three traces where the two separate bone vibration of the
ears can separate the two and where your middle ear can provide the
summation. Your brain supplies the jumper of your choice. Without
discovery you can abide with perception and not with change. With
discoveries you must accept change. If all is known then one doesn't
have to accept change and can exist without a brain by being a
follower and not a leader.

On 4/28/2010 10:52 PM, Art Unwin wrote:
Please keep it up. I, for one, have missed your lack of connection to
reality. It is very amusing.

tom
K0TAR

Perception is not the same as reality. A mixer in a radio is different
than what is required when seeking diversity. The first is the mixing
of two different frequencies where diversity requires the mixing of
two frequencies of the same except one has a delay. The output of the
latter is three traces where the two separate bone vibration of the
ears can separate the two and where your middle ear can provide the
summation. Your brain supplies the jumper of your choice. Without
discovery you can abide with perception and not with change. With
discoveries you must accept change. If all is known then one doesn't
have to accept change and can exist without a brain by being a
follower and not a leader.

Thanks!

tom
K0TAR

K1TTT wrote:
On Apr 28, 6:45 pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:
how useful is the discussion to the average reader of r.r.a.a.?
Hi Bill,
Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").
Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.
That is for certain.

A paradox.
One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

Yeah, I think I agree with Tom's practical experience/experiment. I
certainly do not think that one antenna is going to do this diversity,
because if it would, it means that there is no need for any of the
diversity systems we know about today, with double antennas, voting
and/or dual receivers.

Richard's concerns are for the definition, which I think in Art's case,
is probably important.


when you take a single rf signal and split it through different
receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. I played with some simple ones years ago

side foray here. Did you try binaural receivers? I've heard of them,
never had a chance to listen to one.


and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

Michael Coslo wrote:
K1TTT wrote:

and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

For diversity, something which you can take advantage of has to be
different between signals from two antennas. They can be at the same
physical location but, for example, have different polarization
(polarization diversity). Or they can be physically separate (space
diversity). However, a key necessity is that the signals from the two
can't be phase coherent if you're combining them. That means you have to
separately detect the two signals with receivers that aren't phase
coherent -- you can't use a single LO for both -- then combine the
signals after detection. If you do try to connect the antennas together
or convert/detect them with the same LO, you'll simply have a single
phased array antenna system.

If you're not combining them, but listening to one or the other but not
both at the same time based on some sort of voting system, you can
detect/convert them any way you want, including using the same LO.

Roy Lewallen, W7EL

Michael Coslo wrote:

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

Actually, the antennas can be co-located, they just have to have
different patterns. There are some researchers in France who did a lot
of work using an active whip next to an active loop.

A pair of crossed dipoles would probably also work, which would have the
advantage that you could use one of them to transmit with.

On Apr 29, 12:30*pm, Michael Coslo wrote:
K1TTT wrote:
On Apr 28, 6:45 pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:
how useful is the discussion to the average reader of r.r.a.a.?
Hi Bill,
Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").
Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, *my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.
That is for certain.

A paradox.
One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

Yeah, I think I agree with Tom's practical experience/experiment. I
certainly do not think that one antenna is going to do this diversity,
because if it would, it means that there is no need for any of the
diversity systems we know about today, with double antennas, voting
and/or dual receivers.

Richard's concerns are for the definition, which I think in Art's case,
is probably important.

* when you take a single rf signal and split it through different

receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. *I played with some simple ones years ago

side foray here. Did you try binaural receivers? I've heard of them,
never had a chance to listen to one.

and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. *that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

* * * * - 73 de Mike N3LI -

When I was an ET in the Air Force I had a TDY assignment attached to a
project with Hughes. They were attempting to to implement in software
what Tom was doing in wetware. The purpose was to send high speed(at
the time) radar data over HF SSB . The project was a success but the
final implementation was very different from "stereo diversity"
basically because they could not program a computer to do what the
brain can do very easily.


Jimmie

JIMMIE wrote:

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

When I was an ET in the Air Force I had a TDY assignment attached to a
project with Hughes. They were attempting to to implement in software
what Tom was doing in wetware. The purpose was to send high speed(at
the time) radar data over HF SSB . The project was a success but the
final implementation was very different from "stereo diversity"
basically because they could not program a computer to do what the
brain can do very easily.

these days, though, it's pretty straightforward.. The whiz-bang MIMO
stuff you see in 802.11n, for instance is one flavor of diversity. Two
antennas at each end gives you 4 possible paths (A:1, A:2, B:1, B:2)
each of which will have different fading and interference properties.

Jim Lux wrote:
Michael Coslo wrote:

But aside from that little foray, I have no doubt that the effects
that call for diversity antennas/receivers also call for some physical
separation of separate antennas.

Actually, the antennas can be co-located, they just have to have
different patterns. There are some researchers in France who did a lot
of work using an active whip next to an active loop.

A pair of crossed dipoles would probably also work, which would have the
advantage that you could use one of them to transmit with.

Okay, but I'd have to modify (my statement) that as there would have to
be some difference in the antennas, even if co located. Some sort of
difference that would make one antenna receive some particular signal
better than another one. The crossed dipoles are an good example.

As Roy pointed out, it depends on the parameter in question.

- 73 de Mike N3LI -

On Apr 29, 4:30*pm, Michael Coslo wrote:
K1TTT wrote:
On Apr 28, 6:45 pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:
how useful is the discussion to the average reader of r.r.a.a.?
Hi Bill,
Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").
Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, *my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.
That is for certain.

A paradox.
One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

Yeah, I think I agree with Tom's practical experience/experiment. I
certainly do not think that one antenna is going to do this diversity,
because if it would, it means that there is no need for any of the
diversity systems we know about today, with double antennas, voting
and/or dual receivers.

Richard's concerns are for the definition, which I think in Art's case,
is probably important.

* when you take a single rf signal and split it through different

receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. *I played with some simple ones years ago

side foray here. Did you try binaural receivers? I've heard of them,
never had a chance to listen to one.

i tried a few combinations of audio high pass/low pass and different
ssb in each ear. there are some interesting effects you can get that
way that give you spatial effects as you tune across the band. you
can get the feeling that the signals come in one ear and out the other
as you tune across them... interesting once you get used to it on cw,
but probably not much use on other modes.

On Fri, 30 Apr 2010 16:20:48 -0700 (PDT), K1TTT
wrote:

i tried a few combinations of audio high pass/low pass and different
ssb in each ear. there are some interesting effects you can get that
way that give you spatial effects as you tune across the band. you
can get the feeling that the signals come in one ear and out the other
as you tune across them... interesting once you get used to it on cw,
but probably not much use on other modes.


RTTY might have a ping-pong game on acid effect.

73's
Richard Clark, KB7QHC