Date   

Re: Minor annoyance #sdrsharp

prog
 

On Fri, Sep 1, 2017 at 07:18 am, Bingo TheClowno wrote:
When one of my audio cards is not initialized, sdrsharp hangs, it runs in the task manager but no UI.
This looks more like a driver problem that causes PortAudio to never return. There isn't much we can do about it.

Also, I wish I could change the audio devices when I press the stop button not having to go into the
source menu, change to IQ then be able to change audio sources.
The audio input config only makes sense for sound card sources. If it's disabled in the GUI and you feel the need to touch it, then you are most likely doing something wrong.


Minor annoyance #sdrsharp

Bingo TheClowno
 

When one of my audio cards is not initialized, sdrsharp hangs, it runs in the task manager but no UI.
Also, I wish I could change the audio devices when I press the stop button not having to go into the
source menu, change to IQ then be able to change audio sources.


Re: Interest List for HF+ ? #airspyhfplus

prog
 

It looks like Groups.io allows creating sub-groups, so I created a mailing list for those who want to get notified when the pre-orders are open.

To get the notifications, just subscribe to this group: https://airspy.groups.io/g/hfplus


Re: Interest List for HF+ ? #airspyhfplus

David J Taylor
 

From: wb6la@arrl.net

Is there (or might someone please start) an interest list for the HF+ ? I'm very eager and so I check the AirSpy web site daily. But this is taking much time. And, at some point, I may begin to overlook doing so. A message in my email inbox at the time of release would save me a great deal of time and bother.

Thanks very much!

Cheers,
======================================

Personally, I would prefer to see everything to do with Airspy and SDR# in one place. The lists were separate before, and are now joint, and I find the new arrangement better.

73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv


Interest List for HF+ ? #airspyhfplus

wb6la@...
 

Is there (or might someone please start) an interest list for the HF+ ? I'm very eager and so I check the AirSpy web site daily. But this is taking much time. And, at some point, I may begin to overlook doing so. A message in my email inbox at the time of release would save me a great deal of time and bother.

Thanks very much!

Cheers,


Re: Ideas for cheap and effective loop antennas

jdow
 

Honest injun I only sent it once.
{o.o}

On 2017-08-31 13:03, jdow wrote:
Depends on why they are there. As frequency reference elements or undisciplined oscillators I'd not think much of them compared to an ultra-cheap floor sweepings crystal oscillator. As an element in a phase lock loop synthesizer the design of the oscillator may make it bad but otherwise that's a legitimate use. So without more background information I've no opinion.
I'd note that a fairly complex synthesizer design can use two or even more phase locked LC oscillators to give fast acquisition time and very small step sizes. And I tend to like LC oscillators more than RC oscillators for most anything RFish. That's my high dynamic range bias showing.
{^_^}
On 2017-08-31 12:49, Bob Thornburg wrote:
By all means get out of the box, but only after you are assured that all those working things inside the box won't pull the train. There is very little left outside of the box when using available parts on a time and price limited scale. For example, look at the 3-D printer maker library. It has grown from a few hundred free designs 10 years ago to well over 10 million. You can almost design using your search engine.

Back to receivers a bit. What is your opinion on the dual LC oscillators that are now appearing in commercial HF receivers?

Bob
----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Thursday, August 31, 2017 12:18 PM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


I discovered that about half the jobs people wanted me to do followed by some suggestions about how it should be done were, "It just won't work!" I found myself saying that an awful lot. It puts a premium on the next thing you say, "But I think I have a way we can accomplish the desired end result without some of that mess in the middle." That is what happened with the martini olive satellite thinguabob I designed. The original plan I inherited called for a full blown super heterodyne receiver and a fancy transmitter made impossibly small all to be fit in a package that was mostly battery. "It ain't gonna work! But, maybe if we try this direct conversion design with wee tiny SAW filters the receiver might work."

Then we ran into the transmitter. By this time I'd developed a habit of trying to reduce complexity in the design world I worked with. This involved things like figuring out there are only two types of oscillators used in the RF world. The Pierce/Colpitts/yatta distinctions are meaningless. They simply describe where you place the "ground" node in the oscillator. We'll, in developing the prelaunch test receiver for the Phase II GPS satellites I'd noticed while aligning it I'd see an interesting phase/amplitude trace on the DBM modulator. It went down real low and then spiraled around 180 degrees. (The P and C/A were merged after this modulation stage.) This was filed in my head. So when I needed an insanely tiny and low power modulator for my martini it popped into my head. The design used a SAW oscillator with a varactor diode and a brief pulse from nominal frequency for a specific length of time. The spectrum was truly dreadful; but, the critical thing is that it worked when fed to a PSK demodulator.

All this says, when you are looking at the world in which you are working train yourself to simplify your thinking by avoiding silly (Pierce/Colpitts) distinctions and keep your eyes open for, "That's funny!" With that and a love for what you're doing you can move yourself from an average generally unimaginative engineer into a rather imaginative problem solver engineer. That's all I did. That's why I detest meaningless distinctions. (And, I am absolutely sure I have not purged myself from making meaningless distinctions. I'm human.) My real failure as an engineer is that I never kept a really good engineer's notebook. I regret that - not that I would have ever gone back to read it knowing me. The record might have helped somebody else.)

And the world's best high comes from seeing your design work when you had to beat your brains out to get there.

{^_^}

On 2017-08-30 20:04, Bob Thornburg wrote:
Fine you are an engineer that must deal with reality and seemingly have no room for physics or mathematics or other sciences which deal with concepts and theories. A 1:1 SWR in a cable indeed has only one traveling wave. It is a shame you don't appreciate the language of sciences which are full of non-realizable entities like infinity zero, volts, etc.

BTW, you are one damn good engineer!!

Bob

----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 10:44 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


So basically you are saying every transmission line hosts some level of standing wave pattern, right? There exists a "forward" "traveling wave" of some amplitude and one or more "reverse", or reflected, "traveling waves" with magnitudes related to the "forward" "traveling wave" by generally constant multipliers which may be quite small leading to an instrumentation artifact called a "standing wave" pattern. Or is there some arbitrarily defined value for the reflected "traveling wave" multiplier below which it is declared you don't see a "standing wave" pattern only a "traveling wave" patterm? Thus an antenna with a termination to minimize the reflection coefficient is called a "traveling wave" antenna for purely semantic reasons.

Even if the coefficient is one part per million for the reflected signal you still get a theoretically measurable standing wave pattern on the feed lines. So the distinction between traveling and standing wave antennas gets "confusing" to say the least as the reflection coefficient for a Beverage antenna may be much higher than for a resonant dipole.

The more one digs on this linguistic peculiarity the worse the scab bleeds. Therefore I choose to simply eliminate "traveling wave" from my vocabulary and relegate "standing wave" to mean that measurable distribution of energy peaks and valleys in feed lines which is indicative of some level of impedance mismatch within a distributed RLC network called a feed line. My head hurts less and I can get on with "making it work". Analytic tools that eschew this vocabulary exist and are more powerful than that provided by the two words in question. S parameters, reflection coefficients, and the lot work nicely.

{^_^}

On 2017-08-30 10:18, Bob Thornburg wrote:
Doug..It is not semantics at all, it is physics. Or at least physics explains it....Yes you can have a fine traveling wave antenna with very pure traveling wave and have a high SWR at the transceiver.

A traveling wave on a conductor is a nice hunk of electromagnetic energy going in one direction. When it encounters a change in impedance the wave must lose some energy somewhere so it creates a traveling wave traveling in the reverse direction equal to the energy it couldn't pass on. After the discontinuity in impedance the energy it could pass on continues as a traveling wave.

The standing wave occurs from the interaction of the traveling wave going forward and the reflected traveling wave from the discontinuity. These two combine to create a stationary peak and valley in the current and voltage (each in different places so the energy is still everywhere).

Bob

----- Original Message ----- From: "Leif Asbrink" <leif@sm5bsz.com>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 8:43 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


Doug,

Semantics...

Do you really argue that the wave inside my antenna
cable with VSWR 3:1 is a standing wave?

Most often we would regard it as a forward wave of e.g.
power 100W plus a reflected wave of 25W. With this
terminology the waves are travelling.

Do you mean that the waves we have inside coaxial
cables are not travelling waves??

Surely a standing wave can not transfer energy from
one end of a cable to the other.

The VSWR=3 case can be described as a travelling wave
in the forward direction with power = 75W plus a standing
wave. I do not know how the power of a standing wave
is defined. (In this case composed of 25W in one direction
and 25 W in the other.)

Wire antennas that are very long (in terms of wavelengths)
can be seen as lossy transmission lines.) To get the exact
radiation pattern one would need to know the current at
all points along the wire(s) but if the forward current
is dominating the pattern is easier to understand. There
would not be deep nulls....

Note that I was arguing against this statement that Joanne
made: "In context 'traveling' is semantically meaningless.
It's not something you can measure." I argue that a SWR
meter is the instrument we use on cables and that it measures
the power travelling in both directions. Further I
argue we can do the same measurement on a wire in free space:-)

73

Leif





On 08/29/2017 05:15 PM, Leif Asbrink wrote:
Joanne,

To measure the direction of a travelling wave we can measure the
phase angle between the magnetic field and the electric field
(as in a SWR bridge.)

We can also investigate a very long (in terms of wavelengths)
antenna wire by sending a wideband pulse into it ans see
how the pulse travels along the wire. Signals of different
frequency do not interact, they just superimpose so narrowband
signals have to travel the same way as pulses. Surely a pulse
might be reflected at various discontinuities, but there
is a direct relation between the pulse response and the
frequency response - and in both cases waves travel. One direction
or the other. And we can measure it.

73

Leif
Yes, that combination of forward and reflected wave is called a STANDING
wave, not a traveling wave.
The only time I've heard of traveling wave is in the microwave tube, but
there may be other instances.
The old slotted line shows you that right away.

--doug, WA2SAY




On Tue, 29 Aug 2017 06:26:48 -0700
"jdow" <jdow@earthlink.net> wrote:

That's as good an argument that "traveling wave" is a most >> >>
misleading >>
term. In
context "traveling" is semantically meaningless. It's not >>
something >>  you
can measure.

{^_-}

On 2017-08-29 03:26, Martin via Groups.Io wrote:
On Mon, Aug 28, 2017 at 03:04 pm, jdow wrote:

However there is a some form of static pattern if the excitation >>>
power is
not changed. It's not traveling. It just moved when frequency >>>
moved.

I think the term is probably misleading.

It's really more about current distribution along the radiating >>>
element. Most
'travelling' wave antennas are several wavelengths long,

Imagine if we were to run an RF current probe along a very long >>> (in
terms of
wavelengths) antenna wire.

With a 'standing wave' antenna i.e. one that doesn't have a load >>> of
some sort at
the far end. We would see peaks and dips (standing wave pattern) >>> in
the current
distribution along the wire at regular intervals (the spacing >>>
depending upon the
excitation frequency), with the overall current diminishing (due >>> to
radiation
from the wire) as we move towards the end of the wire. The peaks >>>
and >>>
troughs of
the current variations along the wire would depend on how much of   >>>
the >>>
original
RF energy had been radiated along the wire and what proportion >>> made
it to the
end and then got reflected back.

If the wire was very long, very little would be reflected back >>>
and >>>
so >>>
the
variation in peaks and troughs would be very small and we would >>>
then >>>
have
something more like a 'travelling' wave antenna. With an >>>
intermediate >>>
length of
antenna wire, we have something in-between. Adding a terminating >>>
load >>>
at the end
of a shorter length of wire simulates the longer length, but of >>>
course some of
the power ends up in the terminating load rather than being >>>
radiated >>>
(as would
be the case with a very long wire).

Regards,

Martin - G8JNJ




.
















Re: Ideas for cheap and effective loop antennas

jdow
 

Depends on why they are there. As frequency reference elements or undisciplined oscillators I'd not think much of them compared to an ultra-cheap floor sweepings crystal oscillator. As an element in a phase lock loop synthesizer the design of the oscillator may make it bad but otherwise that's a legitimate use. So without more background information I've no opinion.

I'd note that a fairly complex synthesizer design can use two or even more phase locked LC oscillators to give fast acquisition time and very small step sizes. And I tend to like LC oscillators more than RC oscillators for most anything RFish. That's my high dynamic range bias showing.

{^_^}

On 2017-08-31 12:49, Bob Thornburg wrote:
By all means get out of the box, but only after you are assured that all those working things inside the box won't pull the train. There is very little left outside of the box when using available parts on a time and price limited scale. For example, look at the 3-D printer maker library. It has grown from a few hundred free designs 10 years ago to well over 10 million. You can almost design using your search engine.
Back to receivers a bit. What is your opinion on the dual LC oscillators that are now appearing in commercial HF receivers?
Bob
----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Thursday, August 31, 2017 12:18 PM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas

I discovered that about half the jobs people wanted me to do followed by some suggestions about how it should be done were, "It just won't work!" I found myself saying that an awful lot. It puts a premium on the next thing you say, "But I think I have a way we can accomplish the desired end result without some of that mess in the middle." That is what happened with the martini olive satellite thinguabob I designed. The original plan I inherited called for a full blown super heterodyne receiver and a fancy transmitter made impossibly small all to be fit in a package that was mostly battery. "It ain't gonna work! But, maybe if we try this direct conversion design with wee tiny SAW filters the receiver might work."

Then we ran into the transmitter. By this time I'd developed a habit of trying to reduce complexity in the design world I worked with. This involved things like figuring out there are only two types of oscillators used in the RF world. The Pierce/Colpitts/yatta distinctions are meaningless. They simply describe where you place the "ground" node in the oscillator. We'll, in developing the prelaunch test receiver for the Phase II GPS satellites I'd noticed while aligning it I'd see an interesting phase/amplitude trace on the DBM modulator. It went down real low and then spiraled around 180 degrees. (The P and C/A were merged after this modulation stage.) This was filed in my head. So when I needed an insanely tiny and low power modulator for my martini it popped into my head. The design used a SAW oscillator with a varactor diode and a brief pulse from nominal frequency for a specific length of time. The spectrum was truly dreadful; but, the critical thing is that it worked when fed to a PSK demodulator.

All this says, when you are looking at the world in which you are working train yourself to simplify your thinking by avoiding silly (Pierce/Colpitts) distinctions and keep your eyes open for, "That's funny!" With that and a love for what you're doing you can move yourself from an average generally unimaginative engineer into a rather imaginative problem solver engineer. That's all I did. That's why I detest meaningless distinctions. (And, I am absolutely sure I have not purged myself from making meaningless distinctions. I'm human.) My real failure as an engineer is that I never kept a really good engineer's notebook. I regret that - not that I would have ever gone back to read it knowing me. The record might have helped somebody else.)

And the world's best high comes from seeing your design work when you had to beat your brains out to get there.

{^_^}

On 2017-08-30 20:04, Bob Thornburg wrote:
Fine you are an engineer that must deal with reality and seemingly have no room for physics or mathematics or other sciences which deal with concepts and theories. A 1:1 SWR in a cable indeed has only one traveling wave. It is a shame you don't appreciate the language of sciences which are full of non-realizable entities like infinity zero, volts, etc.

BTW, you are one damn good engineer!!

Bob

----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 10:44 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


So basically you are saying every transmission line hosts some level of standing wave pattern, right? There exists a "forward" "traveling wave" of some amplitude and one or more "reverse", or reflected, "traveling waves" with magnitudes related to the "forward" "traveling wave" by generally constant multipliers which may be quite small leading to an instrumentation artifact called a "standing wave" pattern. Or is there some arbitrarily defined value for the reflected "traveling wave" multiplier below which it is declared you don't see a "standing wave" pattern only a "traveling wave" patterm? Thus an antenna with a termination to minimize the reflection coefficient is called a "traveling wave" antenna for purely semantic reasons.

Even if the coefficient is one part per million for the reflected signal you still get a theoretically measurable standing wave pattern on the feed lines. So the distinction between traveling and standing wave antennas gets "confusing" to say the least as the reflection coefficient for a Beverage antenna may be much higher than for a resonant dipole.

The more one digs on this linguistic peculiarity the worse the scab bleeds. Therefore I choose to simply eliminate "traveling wave" from my vocabulary and relegate "standing wave" to mean that measurable distribution of energy peaks and valleys in feed lines which is indicative of some level of impedance mismatch within a distributed RLC network called a feed line. My head hurts less and I can get on with "making it work". Analytic tools that eschew this vocabulary exist and are more powerful than that provided by the two words in question. S parameters, reflection coefficients, and the lot work nicely.

{^_^}

On 2017-08-30 10:18, Bob Thornburg wrote:
Doug..It is not semantics at all, it is physics. Or at least physics explains it....Yes you can have a fine traveling wave antenna with very pure traveling wave and have a high SWR at the transceiver.

A traveling wave on a conductor is a nice hunk of electromagnetic energy going in one direction. When it encounters a change in impedance the wave must lose some energy somewhere so it creates a traveling wave traveling in the reverse direction equal to the energy it couldn't pass on. After the discontinuity in impedance the energy it could pass on continues as a traveling wave.

The standing wave occurs from the interaction of the traveling wave going forward and the reflected traveling wave from the discontinuity. These two combine to create a stationary peak and valley in the current and voltage (each in different places so the energy is still everywhere).

Bob

----- Original Message ----- From: "Leif Asbrink" <leif@sm5bsz.com>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 8:43 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


Doug,

Semantics...

Do you really argue that the wave inside my antenna
cable with VSWR 3:1 is a standing wave?

Most often we would regard it as a forward wave of e.g.
power 100W plus a reflected wave of 25W. With this
terminology the waves are travelling.

Do you mean that the waves we have inside coaxial
cables are not travelling waves??

Surely a standing wave can not transfer energy from
one end of a cable to the other.

The VSWR=3 case can be described as a travelling wave
in the forward direction with power = 75W plus a standing
wave. I do not know how the power of a standing wave
is defined. (In this case composed of 25W in one direction
and 25 W in the other.)

Wire antennas that are very long (in terms of wavelengths)
can be seen as lossy transmission lines.) To get the exact
radiation pattern one would need to know the current at
all points along the wire(s) but if the forward current
is dominating the pattern is easier to understand. There
would not be deep nulls....

Note that I was arguing against this statement that Joanne
made: "In context 'traveling' is semantically meaningless.
It's not something you can measure." I argue that a SWR
meter is the instrument we use on cables and that it measures
the power travelling in both directions. Further I
argue we can do the same measurement on a wire in free space:-)

73

Leif





On 08/29/2017 05:15 PM, Leif Asbrink wrote:
Joanne,

To measure the direction of a travelling wave we can measure the
phase angle between the magnetic field and the electric field
(as in a SWR bridge.)

We can also investigate a very long (in terms of wavelengths)
antenna wire by sending a wideband pulse into it ans see
how the pulse travels along the wire. Signals of different
frequency do not interact, they just superimpose so narrowband
signals have to travel the same way as pulses. Surely a pulse
might be reflected at various discontinuities, but there
is a direct relation between the pulse response and the
frequency response - and in both cases waves travel. One direction
or the other. And we can measure it.

73

Leif
Yes, that combination of forward and reflected wave is called a STANDING
wave, not a traveling wave.
The only time I've heard of traveling wave is in the microwave tube, but
there may be other instances.
The old slotted line shows you that right away.

--doug, WA2SAY




On Tue, 29 Aug 2017 06:26:48 -0700
"jdow" <jdow@earthlink.net> wrote:

That's as good an argument that "traveling wave" is a most >> >>
misleading >>
term. In
context "traveling" is semantically meaningless. It's not >> something   you
can measure.

{^_-}

On 2017-08-29 03:26, Martin via Groups.Io wrote:
On Mon, Aug 28, 2017 at 03:04 pm, jdow wrote:

However there is a some form of static pattern if the excitation >>>
power is
not changed. It's not traveling. It just moved when frequency >>>
moved.

I think the term is probably misleading.

It's really more about current distribution along the radiating >>>  >>>
element. Most
'travelling' wave antennas are several wavelengths long,

Imagine if we were to run an RF current probe along a very long >>> (in
terms of
wavelengths) antenna wire.

With a 'standing wave' antenna i.e. one that doesn't have a load >>> of
some sort at
the far end. We would see peaks and dips (standing wave pattern) >>> in
the current
distribution along the wire at regular intervals (the spacing >>>
depending upon the
excitation frequency), with the overall current diminishing (due >>> to
radiation
from the wire) as we move towards the end of the wire. The peaks >>>
and >>>
troughs of
the current variations along the wire would depend on how much of   >>>
the >>>
original
RF energy had been radiated along the wire and what proportion >>> made
it to the
end and then got reflected back.

If the wire was very long, very little would be reflected back >>>
and >>>
so >>>
the
variation in peaks and troughs would be very small and we would >>>  >>>
then >>>
have
something more like a 'travelling' wave antenna. With an >>>
intermediate >>>
length of
antenna wire, we have something in-between. Adding a terminating >>>
load >>>
at the end
of a shorter length of wire simulates the longer length, but of >>>  >>>
course some of
the power ends up in the terminating load rather than being >>>
radiated >>>
(as would
be the case with a very long wire).

Regards,

Martin - G8JNJ




.













Re: Ideas for cheap and effective loop antennas

Bob Thornburg <wolfbob@...>
 

By all means get out of the box, but only after you are assured that all those working things inside the box won't pull the train. There is very little left outside of the box when using available parts on a time and price limited scale. For example, look at the 3-D printer maker library. It has grown from a few hundred free designs 10 years ago to well over 10 million. You can almost design using your search engine.

Back to receivers a bit. What is your opinion on the dual LC oscillators that are now appearing in commercial HF receivers?

Bob

----- Original Message -----
From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Thursday, August 31, 2017 12:18 PM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


I discovered that about half the jobs people wanted me to do followed by some suggestions about how it should be done were, "It just won't work!" I found myself saying that an awful lot. It puts a premium on the next thing you say, "But I think I have a way we can accomplish the desired end result without some of that mess in the middle." That is what happened with the martini olive satellite thinguabob I designed. The original plan I inherited called for a full blown super heterodyne receiver and a fancy transmitter made impossibly small all to be fit in a package that was mostly battery. "It ain't gonna work! But, maybe if we try this direct conversion design with wee tiny SAW filters the receiver might work."

Then we ran into the transmitter. By this time I'd developed a habit of trying to reduce complexity in the design world I worked with. This involved things like figuring out there are only two types of oscillators used in the RF world. The Pierce/Colpitts/yatta distinctions are meaningless. They simply describe where you place the "ground" node in the oscillator. We'll, in developing the prelaunch test receiver for the Phase II GPS satellites I'd noticed while aligning it I'd see an interesting phase/amplitude trace on the DBM modulator. It went down real low and then spiraled around 180 degrees. (The P and C/A were merged after this modulation stage.) This was filed in my head. So when I needed an insanely tiny and low power modulator for my martini it popped into my head. The design used a SAW oscillator with a varactor diode and a brief pulse from nominal frequency for a specific length of time. The spectrum was truly dreadful; but, the critical thing is that it worked when fed to a PSK demodulator.

All this says, when you are looking at the world in which you are working train yourself to simplify your thinking by avoiding silly (Pierce/Colpitts) distinctions and keep your eyes open for, "That's funny!" With that and a love for what you're doing you can move yourself from an average generally unimaginative engineer into a rather imaginative problem solver engineer. That's all I did. That's why I detest meaningless distinctions. (And, I am absolutely sure I have not purged myself from making meaningless distinctions. I'm human.) My real failure as an engineer is that I never kept a really good engineer's notebook. I regret that - not that I would have ever gone back to read it knowing me. The record might have helped somebody else.)

And the world's best high comes from seeing your design work when you had to beat your brains out to get there.

{^_^}

On 2017-08-30 20:04, Bob Thornburg wrote:
Fine you are an engineer that must deal with reality and seemingly have no room for physics or mathematics or other sciences which deal with concepts and theories. A 1:1 SWR in a cable indeed has only one traveling wave. It is a shame you don't appreciate the language of sciences which are full of non-realizable entities like infinity zero, volts, etc.

BTW, you are one damn good engineer!!

Bob

----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 10:44 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


So basically you are saying every transmission line hosts some level of standing wave pattern, right? There exists a "forward" "traveling wave" of some amplitude and one or more "reverse", or reflected, "traveling waves" with magnitudes related to the "forward" "traveling wave" by generally constant multipliers which may be quite small leading to an instrumentation artifact called a "standing wave" pattern. Or is there some arbitrarily defined value for the reflected "traveling wave" multiplier below which it is declared you don't see a "standing wave" pattern only a "traveling wave" patterm? Thus an antenna with a termination to minimize the reflection coefficient is called a "traveling wave" antenna for purely semantic reasons.

Even if the coefficient is one part per million for the reflected signal you still get a theoretically measurable standing wave pattern on the feed lines. So the distinction between traveling and standing wave antennas gets "confusing" to say the least as the reflection coefficient for a Beverage antenna may be much higher than for a resonant dipole.

The more one digs on this linguistic peculiarity the worse the scab bleeds. Therefore I choose to simply eliminate "traveling wave" from my vocabulary and relegate "standing wave" to mean that measurable distribution of energy peaks and valleys in feed lines which is indicative of some level of impedance mismatch within a distributed RLC network called a feed line. My head hurts less and I can get on with "making it work". Analytic tools that eschew this vocabulary exist and are more powerful than that provided by the two words in question. S parameters, reflection coefficients, and the lot work nicely.

{^_^}

On 2017-08-30 10:18, Bob Thornburg wrote:
Doug..It is not semantics at all, it is physics. Or at least physics explains it....Yes you can have a fine traveling wave antenna with very pure traveling wave and have a high SWR at the transceiver.

A traveling wave on a conductor is a nice hunk of electromagnetic energy going in one direction. When it encounters a change in impedance the wave must lose some energy somewhere so it creates a traveling wave traveling in the reverse direction equal to the energy it couldn't pass on. After the discontinuity in impedance the energy it could pass on continues as a traveling wave.

The standing wave occurs from the interaction of the traveling wave going forward and the reflected traveling wave from the discontinuity. These two combine to create a stationary peak and valley in the current and voltage (each in different places so the energy is still everywhere).

Bob

----- Original Message ----- From: "Leif Asbrink" <leif@sm5bsz.com>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 8:43 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


Doug,

Semantics...

Do you really argue that the wave inside my antenna
cable with VSWR 3:1 is a standing wave?

Most often we would regard it as a forward wave of e.g.
power 100W plus a reflected wave of 25W. With this
terminology the waves are travelling.

Do you mean that the waves we have inside coaxial
cables are not travelling waves??

Surely a standing wave can not transfer energy from
one end of a cable to the other.

The VSWR=3 case can be described as a travelling wave
in the forward direction with power = 75W plus a standing
wave. I do not know how the power of a standing wave
is defined. (In this case composed of 25W in one direction
and 25 W in the other.)

Wire antennas that are very long (in terms of wavelengths)
can be seen as lossy transmission lines.) To get the exact
radiation pattern one would need to know the current at
all points along the wire(s) but if the forward current
is dominating the pattern is easier to understand. There
would not be deep nulls....

Note that I was arguing against this statement that Joanne
made: "In context 'traveling' is semantically meaningless.
It's not something you can measure." I argue that a SWR
meter is the instrument we use on cables and that it measures
the power travelling in both directions. Further I
argue we can do the same measurement on a wire in free space:-)

73

Leif





On 08/29/2017 05:15 PM, Leif Asbrink wrote:
Joanne,

To measure the direction of a travelling wave we can measure the
phase angle between the magnetic field and the electric field
(as in a SWR bridge.)

We can also investigate a very long (in terms of wavelengths)
antenna wire by sending a wideband pulse into it ans see
how the pulse travels along the wire. Signals of different
frequency do not interact, they just superimpose so narrowband
signals have to travel the same way as pulses. Surely a pulse
might be reflected at various discontinuities, but there
is a direct relation between the pulse response and the
frequency response - and in both cases waves travel. One direction
or the other. And we can measure it.

73

Leif
Yes, that combination of forward and reflected wave is called a STANDING
wave, not a traveling wave.
The only time I've heard of traveling wave is in the microwave tube, but
there may be other instances.
The old slotted line shows you that right away.

--doug, WA2SAY




On Tue, 29 Aug 2017 06:26:48 -0700
"jdow" <jdow@earthlink.net> wrote:

That's as good an argument that "traveling wave" is a most >> misleading >>
term. In
context "traveling" is semantically meaningless. It's not something >> you
can measure.

{^_-}

On 2017-08-29 03:26, Martin via Groups.Io wrote:
On Mon, Aug 28, 2017 at 03:04 pm, jdow wrote:

However there is a some form of static pattern if the excitation
>>> >>>
power is
not changed. It's not traveling. It just moved when frequency >>>
moved.

I think the term is probably misleading.

It's really more about current distribution along the radiating
>>>
element. Most
'travelling' wave antennas are several wavelengths long,

Imagine if we were to run an RF current probe along a very long (in
terms of
wavelengths) antenna wire.

With a 'standing wave' antenna i.e. one that doesn't have a load of
some sort at
the far end. We would see peaks and dips (standing wave pattern) in
the current
distribution along the wire at regular intervals (the spacing >>>
depending upon the
excitation frequency), with the overall current diminishing (due to
radiation
from the wire) as we move towards the end of the wire. The peaks
>>>
and >>>
troughs of
the current variations along the wire would depend on how much of
>>>
the >>>
original
RF energy had been radiated along the wire and what proportion made
it to the
end and then got reflected back.

If the wire was very long, very little would be reflected back and >>>
so >>>
the
variation in peaks and troughs would be very small and we would
>>>
then >>>
have
something more like a 'travelling' wave antenna. With an >>>
intermediate >>>
length of
antenna wire, we have something in-between. Adding a terminating
>>>
load >>>
at the end
of a shorter length of wire simulates the longer length, but of
>>>
course some of
the power ends up in the terminating load rather than being >>>
radiated >>>
(as would
be the case with a very long wire).

Regards,

Martin - G8JNJ




.












Re: ADSBspy settings for Airspy Mini?

David J Taylor
 

On Thu, Aug 31, 2017 at 12:23 pm, David J Taylor wrote:
Is there a published CLI version for X86 Windows.

Try this one: http://airspy.com/downloads/airspy_adsb_win32.zip =======================

Many thanks!

David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv


Re: ADSBspy settings for Airspy Mini?

prog
 

On Thu, Aug 31, 2017 at 12:23 pm, David J Taylor wrote:
Is there a published CLI version for X86 Windows.
Try this one: http://airspy.com/downloads/airspy_adsb_win32.zip


Re: ADSBspy settings for Airspy Mini?

David J Taylor
 

The GUI version should perform exactly the same with all units. The CLI version has more options you can fiddle with. By default all units run at 20MSPS (including the Mini).
==========================

Thanks, Youssef, 20 Msps is an excellent rate and helpful for best multilateration.

Is there a published CLI version for X86 Windows. The only one I found is for the RPi and is the one I've been running.

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv


Re: Ideas for cheap and effective loop antennas

jdow
 

I discovered that about half the jobs people wanted me to do followed by some suggestions about how it should be done were, "It just won't work!" I found myself saying that an awful lot. It puts a premium on the next thing you say, "But I think I have a way we can accomplish the desired end result without some of that mess in the middle." That is what happened with the martini olive satellite thinguabob I designed. The original plan I inherited called for a full blown super heterodyne receiver and a fancy transmitter made impossibly small all to be fit in a package that was mostly battery. "It ain't gonna work! But, maybe if we try this direct conversion design with wee tiny SAW filters the receiver might work."

Then we ran into the transmitter. By this time I'd developed a habit of trying to reduce complexity in the design world I worked with. This involved things like figuring out there are only two types of oscillators used in the RF world. The Pierce/Colpitts/yatta distinctions are meaningless. They simply describe where you place the "ground" node in the oscillator. We'll, in developing the prelaunch test receiver for the Phase II GPS satellites I'd noticed while aligning it I'd see an interesting phase/amplitude trace on the DBM modulator. It went down real low and then spiraled around 180 degrees. (The P and C/A were merged after this modulation stage.) This was filed in my head. So when I needed an insanely tiny and low power modulator for my martini it popped into my head. The design used a SAW oscillator with a varactor diode and a brief pulse from nominal frequency for a specific length of time. The spectrum was truly dreadful; but, the critical thing is that it worked when fed to a PSK demodulator.

All this says, when you are looking at the world in which you are working train yourself to simplify your thinking by avoiding silly (Pierce/Colpitts) distinctions and keep your eyes open for, "That's funny!" With that and a love for what you're doing you can move yourself from an average generally unimaginative engineer into a rather imaginative problem solver engineer. That's all I did. That's why I detest meaningless distinctions. (And, I am absolutely sure I have not purged myself from making meaningless distinctions. I'm human.) My real failure as an engineer is that I never kept a really good engineer's notebook. I regret that - not that I would have ever gone back to read it knowing me. The record might have helped somebody else.)

And the world's best high comes from seeing your design work when you had to beat your brains out to get there.

{^_^}

On 2017-08-30 20:04, Bob Thornburg wrote:
Fine you are an engineer that must deal with reality and seemingly have no room for physics or mathematics or other sciences which deal with concepts and theories.  A 1:1 SWR in a cable indeed has only one traveling wave. It is a shame you don't appreciate the language of sciences which are full of non-realizable entities like infinity zero, volts, etc.
BTW, you are one damn good engineer!!
Bob
----- Original Message ----- From: "jdow" <jdow@earthlink.net>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 10:44 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas

So basically you are saying every transmission line hosts some level of standing wave pattern, right? There exists a "forward" "traveling wave" of some amplitude and one or more "reverse", or reflected, "traveling waves" with magnitudes related to the "forward" "traveling wave" by generally constant multipliers which may be quite small leading to an instrumentation artifact called a "standing wave" pattern. Or is there some arbitrarily defined value for the reflected "traveling wave" multiplier below which it is declared you don't see a "standing wave" pattern only a "traveling wave" patterm? Thus an antenna with a termination to minimize the reflection coefficient is called a "traveling wave" antenna for purely semantic reasons.

Even if the coefficient is one part per million for the reflected signal you still get a theoretically measurable standing wave pattern on the feed lines. So the distinction between traveling and standing wave antennas gets "confusing" to say the least as the reflection coefficient for a Beverage antenna may be much higher than for a resonant dipole.

The more one digs on this linguistic peculiarity the worse the scab bleeds. Therefore I choose to simply eliminate "traveling wave" from my vocabulary and relegate "standing wave" to mean that measurable distribution of energy peaks and valleys in feed lines which is indicative of some level of impedance mismatch within a distributed RLC network called a feed line. My head hurts less and I can get on with "making it work". Analytic tools that eschew this vocabulary exist and are more powerful than that provided by the two words in question. S parameters, reflection coefficients, and the lot work nicely.

{^_^}

On 2017-08-30 10:18, Bob Thornburg wrote:
Doug..It is not semantics at all, it is physics. Or at least physics explains it....Yes you can have a fine traveling wave antenna with very pure traveling wave and have a high SWR at the transceiver.

A traveling wave on a conductor is a nice hunk of electromagnetic energy going in one direction. When it encounters a change in impedance the wave must lose some energy somewhere so it creates a traveling wave traveling in the reverse direction equal to the energy it couldn't pass on. After the discontinuity in impedance the energy it could pass on continues as a traveling wave.

The standing wave occurs from the interaction of the traveling wave going forward and the reflected traveling wave from the discontinuity. These two combine to create a stationary peak and valley in the current and voltage (each in different places so the energy is still everywhere).

Bob

----- Original Message ----- From: "Leif Asbrink" <leif@sm5bsz.com>
To: <airspy@groups.io>
Sent: Wednesday, August 30, 2017 8:43 AM
Subject: Re: [airspy] Ideas for cheap and effective loop antennas


Doug,

Semantics...

Do you really argue that the wave inside my antenna
cable with VSWR 3:1 is a standing wave?

Most often we would regard it as a forward wave of e.g.
power 100W plus a reflected wave of 25W. With this
terminology the waves are travelling.

Do you mean that the waves we have inside coaxial
cables are not travelling waves??

Surely a standing wave can not transfer energy from
one end of a cable to the other.

The VSWR=3 case can be described as a travelling wave
in the forward direction with power = 75W plus a standing
wave. I do not know how the power of a standing wave
is defined. (In this case composed of 25W in one direction
and 25 W in the other.)

Wire antennas that are very long (in terms of wavelengths)
can be seen as lossy transmission lines.) To get the exact
radiation pattern one would need to know the current at
all points along the wire(s) but if the forward current
is dominating the pattern is easier to understand. There
would not be deep nulls....

Note that I was arguing against this statement that Joanne
made: "In context 'traveling' is semantically meaningless.
It's not something you can measure." I argue that a SWR
meter is the instrument we use on cables and that it measures
the power travelling in both directions. Further I
argue we can do the same measurement on a wire in free space:-)

73

Leif





On 08/29/2017 05:15 PM, Leif Asbrink wrote:
Joanne,

To measure the direction of a travelling wave we can measure the
phase angle between the magnetic field and the electric field
(as in a SWR bridge.)

We can also investigate a very long (in terms of wavelengths)
antenna wire by sending a wideband pulse into it ans see
how the pulse travels along the wire. Signals of different
frequency do not interact, they just superimpose so narrowband
signals have to travel the same way as pulses. Surely a pulse
might be reflected at various discontinuities, but there
is a direct relation between the pulse response and the
frequency response - and in both cases waves travel. One direction
or the other. And we can measure it.

73

Leif
Yes, that combination of forward and reflected wave is called a STANDING
wave, not a traveling wave.
The only time I've heard of traveling wave is in the microwave tube, but
there may be other instances.
The old slotted line shows you that right away.

--doug, WA2SAY




On Tue, 29 Aug 2017 06:26:48 -0700
"jdow" <jdow@earthlink.net> wrote:

That's as good an argument that "traveling wave" is a most >> misleading >>
term. In
context "traveling" is semantically meaningless. It's not something >> you
can measure.

{^_-}

On 2017-08-29 03:26, Martin via Groups.Io wrote:
On Mon, Aug 28, 2017 at 03:04 pm, jdow wrote:

However there is a some form of static pattern if the excitation >>>  >>>
power is
not changed. It's not traveling. It just moved when frequency >>>
moved.

I think the term is probably misleading.

It's really more about current distribution along the radiating >>>
element. Most
'travelling' wave antennas are several wavelengths long,

Imagine if we were to run an RF current probe along a very long (in   >>>
terms of
wavelengths) antenna wire.

With a 'standing wave' antenna i.e. one that doesn't have a load of   >>>
some sort at
the far end. We would see peaks and dips (standing wave pattern) in   >>>
the current
distribution along the wire at regular intervals (the spacing >>>
depending upon the
excitation frequency), with the overall current diminishing (due to   >>>
radiation
from the wire) as we move towards the end of the wire. The peaks >>>
and >>>
troughs of
the current variations along the wire would depend on how much of >>>
the >>>
original
RF energy had been radiated along the wire and what proportion made   >>>
it to the
end and then got reflected back.

If the wire was very long, very little would be reflected back and >>>
so >>>
the
variation in peaks and troughs would be very small and we would >>>
then >>>
have
something more like a 'travelling' wave antenna. With an >>>
intermediate >>>
length of
antenna wire, we have something in-between. Adding a terminating >>>
load >>>
at the end
of a shorter length of wire simulates the longer length, but of >>>
course some of
the power ends up in the terminating load rather than being >>>
radiated >>>
(as would
be the case with a very long wire).

Regards,

Martin - G8JNJ




.









Re: Airspy R2 Lockout Question

Henk
 

Greg, there's a high pass filter installed so no FM tx should come through. 

I'm a new Airspy user and I'm afraid my Gain and Squelch settings are not yet perfectly set . Can anyone help me on that please?

gr Henk

2017-08-31 17:32 GMT+02:00 Greg Ella <gregella53@...>:

I'm wondering if some of your interfering signals are caused by intermod with FM broadcast stations, and if a 88-108 MHz band reject filter might help you.

Greg Ella
AD0JP

On Thu, Aug 31, 2017 at 7:18 AM, Henk <henkdemooij@...> wrote:
Hi all,

I have recently purchased an Airspy R2 and I love it.

There are quite some frequencies I had to lock out due to interference. And I've also locked out some 60 frequencies that I also have in a scanner.

Question: is there a limit to the number of locked out freqs one can store in scanner_entryes.xml?
Any help much appreciated.

Regards, Henk
NL




Re: Receive loop antenna - has anyone built this?

Hans J Albertsson
 

C'mon! Stop it! Get back on topic PLEASE!!!!!!!!!

Hans J. Albertsson
From my Nexus 5

Den 31 aug. 2017 18:32 skrev "Alberto I2PHD" <i2phd@...>:

On 8/31/2017 6:23 PM, Alberto I2PHD wrote:
أنا لا أوافق تماما، ولكن الآن 
دعونا وقف هذا هراء

The automatic translator made a grave error... I wrote "I do completely agree"
but the translation was "I do not quite agree"  .....

Never rely on the automatic translations....  :-)

--
73 Alberto I2PHD
Credo Ut Intelligam



Re: Receive loop antenna - has anyone built this?

Alberto I2PHD
 

On 8/31/2017 6:23 PM, Alberto I2PHD wrote:
أنا لا أوافق تماما، ولكن الآن 
دعونا وقف هذا هراء

The automatic translator made a grave error... I wrote "I do completely agree"
but the translation was "I do not quite agree"  .....

Never rely on the automatic translations....  :-)

--
73 Alberto I2PHD
Credo Ut Intelligam



Re: Receive loop antenna - has anyone built this?

Alberto I2PHD
 

On 8/31/2017 5:00 PM, Bernard Malet wrote:
يوسف يكون معقولا

أنا لا أوافق تماما، ولكن الآن 
دعونا وقف هذا هراء


--
73 Alberto I2PHD
Credo Ut Intelligam



Re: Airspy R2 Lockout Question

Greg Ella
 

I'm wondering if some of your interfering signals are caused by intermod with FM broadcast stations, and if a 88-108 MHz band reject filter might help you.

Greg Ella
AD0JP

On Thu, Aug 31, 2017 at 7:18 AM, Henk <henkdemooij@...> wrote:
Hi all,

I have recently purchased an Airspy R2 and I love it.

There are quite some frequencies I had to lock out due to interference. And I've also locked out some 60 frequencies that I also have in a scanner.

Question: is there a limit to the number of locked out freqs one can store in scanner_entryes.xml?
Any help much appreciated.

Regards, Henk
NL



Airspy R2 Lockout Question

Henk
 

Hi all,

I have recently purchased an Airspy R2 and I love it.

There are quite some frequencies I had to lock out due to interference. And I've also locked out some 60 frequencies that I also have in a scanner.

Question: is there a limit to the number of locked out freqs one can store in scanner_entryes.xml?
Any help much appreciated.

Regards, Henk
NL


Re: Receive loop antenna - has anyone built this?

Bernard Malet
 

يوسف يكون معقولا

 

De : airspy@groups.io [mailto:airspy@groups.io] De la part de prog
Envoyé : jeudi 31 août 2017 11:30
À : airspy@groups.io
Objet : Re: [airspy] Receive loop antenna - has anyone built this?

 

سير تقود


Re: ADSBspy settings for Airspy Mini?

prog
 

The GUI version should perform exactly the same with all units. The CLI version has more options you can fiddle with. By default all units run at 20MSPS (including the Mini).

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