Re: [Elecraft] P3 TX Mon: FEATURE REQUEST - Monitoring of RTTY Waveform

[Joe Subich, W4TV]

On 9/14/2015 2:55 PM, Luis V. Romero wrote:
>

However, I can't monitor other issues that can rear their ugly heads
in RTTY, be it modulated by FSK or AFSK with the existing
functionality available: The reason I was looking for a better visual
representation of these issues in this tool is explained in an
excellent article by Andy Flowers, K0SM.

>
> http://frontiernet.net/~aflowers/k3rtty/k3rtty.html

The displays generated by K0SM are frequency domain ... TX MON is
strictly a time domain (amplitude) display.  TX Mon uses a amplitude
detector driven by a directional coupler.  To do what you desire would
require an SDR tuned by frequency data (TX frequency) from the K3.

The difference between an envelope (diode) detector and a tracking SDR
is a couple of orders of magnitude in both cost and complexity.

73,

  ... Joe, W4TV


On 9/14/2015 2:55 PM, Luis V. Romero wrote:

Alan:



You wrote:

It gets more interesting if there is a problem

  in the RTTY transmitter that causes the two tones to come out at

  different amplitudes, which would be easy to see on the screen.



In your example, you would see ripple in the flat waveform on the screen,
true enough.  The Ripple would increase with the amount of the different
amplitudes of the two tones.



However, I can't monitor other issues that can rear their ugly heads in
RTTY, be it modulated by FSK or AFSK with the existing functionality
available:  The reason I was looking for a better visual representation of
these issues in this tool is explained in an excellent article by Andy
Flowers, K0SM.



http://frontiernet.net/~aflowers/k3rtty/k3rtty.html



Gee, it would be nice not to have to buy a Flex rig just to monitor my K3's
output. And I already have an SDR receiver sitting inside the P3 box, locked
to my transmitter frequency.



You wrote:

The traditional "plus sign" (crossed ellipses) display is normally used

  in the FSK receiving demodulator as a tuning aid.  As you tune the

  receiver the ellipses change their angle.  When you see the "plus sign"

  then the receiver is tuned correctly.



Not just for receive, but in transmit as well.  Especially in tone modulated
RTTY (pseudo FSK) using AFSK "tone" modulation.  If one tone is off, it
would be shown in the transmission ellipsoid representation as well.  When
you see a "plus sign", both tones are in phase and in quadrature.  But if
one tone is out of quadrature?  Then you see an ellipse.  We deal with this
daily in the representation of Trellis modulation artifacts in ATV
transmitters.  There we call it "The Eye Pattern". Same display principle.



While the dual ellipse waveform would be ideal, there are alternatives, In
receive, we can see similar information in the two tone demodulation
"envelope" showing two peaks with a valley in between using a single
envelope detector as described bu K0SM. Why not avail us of at least that
waveform, since you already can show it on receive in the P3
hardware/software?  With some handles on the display for gain, width, slope
and maybe a synthetic "mask", it solves this requirement!



You wrote:

You can also see if the transmitter has the wrong (or at least

  different) frequency shift.  In that case the ellipses don't make a

  right angle with each other even when the receiver is tuned correctly.



True and correct.  And I agree.



You wrote:

  That might be useful in a transmit monitor, but it can't be done using

   An RF coupler because it only detects the amplitude, not the frequency.



True: Not the *quadrature* (two ellipsoids) display. But you *can* show the
dual peak/valley display. You already show it on receive!  It is an
equivalent 2-D representation that can be used in addition to the flat
envelope display.  But, alas, I can't see it in transmit (yes, I could
unplug the control cable to see IF "bleedthrough", but what a pain!). The
way it is now, I can only tell folks I am receiving that they are having
problems.  I can't proactively solve my own problems before I transmit with
my monitoring tool!



I don't know. Maybe I'm just old fashioned, but I'm really disappointed to
have waited 5 years and paid $200 for this simple envelope sampler
functionality using a repurposed WM2 sampling bridge.  I sort of expected
more. Maybe not in hardware, but in the application software, as all
hardware for this type of measurement is synthesized in apps anymore.  For
$200 more I could have gotten a Wavenode WN-2, but then I have wasted the
wattmeter again and I would need another PC to run the app software.  But
the funniest thing is that the P3 can display an equivalent waveform today
in receive that does what I need for transmission monitoring!



I'm still no better off and $200 poorer than where I was with my Bench
Oscilloscope and a 17 inch piece of hook up wire, and that is the issue.
It's the first time I have been disappointed by an Elecraft product.





Lu - W4LT





__

Re: [Elecraft] P3 TX Mon: FEATURE REQUEST - Monitoring of RTTY Waveform

[Luis V. Romero]

Alan:

 

You wrote:

It gets more interesting if there is a problem 

 in the RTTY transmitter that causes the two tones to come out at 

 different amplitudes, which would be easy to see on the screen.

 

In your example, you would see ripple in the flat waveform on the screen,
true enough.  The Ripple would increase with the amount of the different
amplitudes of the two tones.

 

However, I can't monitor other issues that can rear their ugly heads in
RTTY, be it modulated by FSK or AFSK with the existing functionality
available:  The reason I was looking for a better visual representation of
these issues in this tool is explained in an excellent article by Andy
Flowers, K0SM.

 

http://frontiernet.net/~aflowers/k3rtty/k3rtty.html

 

Gee, it would be nice not to have to buy a Flex rig just to monitor my K3's
output. And I already have an SDR receiver sitting inside the P3 box, locked
to my transmitter frequency.   

 

You wrote:

The traditional "plus sign" (crossed ellipses) display is normally used 

 in the FSK receiving demodulator as a tuning aid.  As you tune the 

 receiver the ellipses change their angle.  When you see the "plus sign" 

 then the receiver is tuned correctly.

 

Not just for receive, but in transmit as well.  Especially in tone modulated
RTTY (pseudo FSK) using AFSK "tone" modulation.  If one tone is off, it
would be shown in the transmission ellipsoid representation as well.  When
you see a "plus sign", both tones are in phase and in quadrature.  But if
one tone is out of quadrature?  Then you see an ellipse.  We deal with this
daily in the representation of Trellis modulation artifacts in ATV
transmitters.  There we call it "The Eye Pattern". Same display principle. 

 

While the dual ellipse waveform would be ideal, there are alternatives, In
receive, we can see similar information in the two tone demodulation
"envelope" showing two peaks with a valley in between using a single
envelope detector as described bu K0SM. Why not avail us of at least that
waveform, since you already can show it on receive in the P3
hardware/software?  With some handles on the display for gain, width, slope
and maybe a synthetic "mask", it solves this requirement!

 

You wrote:

You can also see if the transmitter has the wrong (or at least 

 different) frequency shift.  In that case the ellipses don't make a 

 right angle with each other even when the receiver is tuned correctly. 

 

True and correct.  And I agree.

 

You wrote:

 That might be useful in a transmit monitor, but it can't be done using 

  An RF coupler because it only detects the amplitude, not the frequency.

 

True: Not the *quadrature* (two ellipsoids) display. But you *can* show the
dual peak/valley display. You already show it on receive!  It is an
equivalent 2-D representation that can be used in addition to the flat
envelope display.  But, alas, I can't see it in transmit (yes, I could
unplug the control cable to see IF "bleedthrough", but what a pain!). The
way it is now, I can only tell folks I am receiving that they are having
problems.  I can't proactively solve my own problems before I transmit with
my monitoring tool!

 

I don't know. Maybe I'm just old fashioned, but I'm really disappointed to
have waited 5 years and paid $200 for this simple envelope sampler
functionality using a repurposed WM2 sampling bridge.  I sort of expected
more. Maybe not in hardware, but in the application software, as all
hardware for this type of measurement is synthesized in apps anymore.  For
$200 more I could have gotten a Wavenode WN-2, but then I have wasted the
wattmeter again and I would need another PC to run the app software.  But
the funniest thing is that the P3 can display an equivalent waveform today
in receive that does what I need for transmission monitoring! 

 

I'm still no better off and $200 poorer than where I was with my Bench
Oscilloscope and a 17 inch piece of hook up wire, and that is the issue.
It's the first time I have been disappointed by an Elecraft product.  

 

 

Lu - W4LT

 

 

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Re: [Elecraft] P3 TX Mon: FEATURE REQUEST - Monitoring of RTTY Waveform

[Alan]

Hi Luis,

As you mentioned, monitoring the amplitude of a properly-functioning 
RTTY transmitter is not very interesting.  Since FSK is a 
constant-amplitude modulation mode, all you see is a constant-amplitude 
envelope on the screen.  It gets more interesting if there is a problem 
in the RTTY transmitter that causes the two tones to come out at 
different amplitudes, which would be easy to see on the screen.


The traditional "plus sign" (crossed ellipses) display is normally used 
in the FSK receiving demodulator as a tuning aid.  As you tune the 
receiver the ellipses change their angle.  When you see the "plus sign" 
then the receiver is tuned correctly.


You can also see if the transmitter has the wrong (or at least 
different) frequency shift.  In that case the ellipses don't make a 
right angle with each other even when the receiver is tuned correctly. 
That might be useful in a transmit monitor, but it can't be done using 
an RF coupler because it only detects the amplitude, not the frequency.


A "trapezoid" display would be interesting, but it requires two RF 
coupler/detectors, one at the input of the amplifier and one at the 
output.  Any non-linearity in the transmitter shows up as a 
non-linearity in the trapezoid.  An alternative that serves the same 
purpose is a "triangle" display, in which the RF signal ramps up and 
down from zero to PEP and back.  You feed the mic input of the SSB 
transmitter with a (say) 1500-Hz sine wave that is modulated with a 
(say) 100 Hz triangle.  The P3 TX monitor would then show any 
non-linearity in a manner similar to a trapezoid.


Alan N1AL


On 09/13/2015 01:29 PM, Luis V. Romero wrote:

Hello Elecraft folk:



Just installed my new P3 TX Monitor board that I ordered at Dayton (!). I
have been waiting for this capability for the P3 since 2010, so as to enable
me to monitor transmitter waveforms accurately like I did in my Heath
SB-401/SB303 station with the SB610 in ancient times (the late '70's).



So now my O'Scope can go back to the bench where it belongs. Since I already
had an accurate dual meter peak reading Wattmeter (Autek WM-1), the bundled
SWR/Wattmeter capability is not important to me.  A good, full featured
visual transmitted waveform monitor was what I was looking for.



However, a big feature is missing from the TX Monitor option:  Accurate
monitoring of the direct FSK signal for RTTY.  All that is visible on RTTY
transmissions is a solid envelope that fills the screen, just like sampling
RF using my bench 'scope.



True, RTTY is a full carrier FM signal, so the display is showing me the
"correct" interpretation for an envelope sampler, but I was hoping to at
least see the same display we see on RTTY receive:  Two pulses with a valley
in between.  If both pulses are equal, there is no passband ripple.  If
there are single peaks and the fall to the valley is smooth and sinusoidal,
all is well and the transmitter is not being overdriven.



My preference, however, would be to see a traditional crossed ellipsis
display like on my old SB610 and the simulated one on software RTTY apps
(that are NOT real transmitted waveforms!), but I can live with the above.
Neither mode is available on the simple envelope sampler add on that
comprises the TX Monitor today.



I don't use AM here, but the a "Trapezoid" display would also be helpful to
set amplifier linearity and peak modulation.



These features would make a P3 with the TX Mon option a real, full featured,
transmission monitor, which was my assumption that it was to be. Right now,
it's a simple envelope sampler which, while helpful (and cute to show off to
guests), doesn't do what a true full featured transmission monitoring tool
*should* do, especially for RTTY and AM, and especially for its price. I can
do most of what it does with a chunk of wire and any o'scope.



Am I out of line with my expectation?  Are these features in the works for a
future software update?  If not, they should be!



Lu Romero - W4LT

K-Line


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Re: [Elecraft] P3 TX Mon: FEATURE REQUEST - Monitoring of RTTY Waveform

[Al Gulseth]

Lu,

Without addressing what any hardware/software changes needed might entail, I'd 
say that you are _not_ "out of line with [your] expectation" Any request 
for features intended help the operator adjust his equipment for a cleaner 
transmitted signal is valid in my opinion. In fact, I tip my hat to you: one 
doesn't have to listen around very much to hear "crud" on the bands coming 
from ops who either don't know and/or don't care about how to adjust things 
properly, so by contrast it's refreshing to find someone who is concerned 
about his signal quality. (I'm sure there are many others on this list who 
also share your desire to strive for the cleanest signal possible.)

73, Al

On Sun September 13 2015 3:29:13 pm Luis V. Romero wrote:
> Hello Elecraft folk:
>
>
>
> Just installed my new P3 TX Monitor board that I ordered at Dayton (!). I
> have been waiting for this capability for the P3 since 2010, so as to
> enable me to monitor transmitter waveforms accurately like I did in my
> Heath SB-401/SB303 station with the SB610 in ancient times (the late
> '70's).
>
>
>
> So now my O'Scope can go back to the bench where it belongs. Since I
> already had an accurate dual meter peak reading Wattmeter (Autek WM-1), the
> bundled SWR/Wattmeter capability is not important to me.  A good, full
> featured visual transmitted waveform monitor was what I was looking for.
>
>
>
> However, a big feature is missing from the TX Monitor option:  Accurate
> monitoring of the direct FSK signal for RTTY.  All that is visible on RTTY
> transmissions is a solid envelope that fills the screen, just like sampling
> RF using my bench 'scope.
>
>
>
> True, RTTY is a full carrier FM signal, so the display is showing me the
> "correct" interpretation for an envelope sampler, but I was hoping to at
> least see the same display we see on RTTY receive:  Two pulses with a
> valley in between.  If both pulses are equal, there is no passband ripple. 
> If there are single peaks and the fall to the valley is smooth and
> sinusoidal, all is well and the transmitter is not being overdriven.
>
>
>
> My preference, however, would be to see a traditional crossed ellipsis
> display like on my old SB610 and the simulated one on software RTTY apps
> (that are NOT real transmitted waveforms!), but I can live with the above.
> Neither mode is available on the simple envelope sampler add on that
> comprises the TX Monitor today.
>
>
>
> I don't use AM here, but the a "Trapezoid" display would also be helpful to
> set amplifier linearity and peak modulation.
>
>
>
> These features would make a P3 with the TX Mon option a real, full
> featured, transmission monitor, which was my assumption that it was to be.
> Right now, it's a simple envelope sampler which, while helpful (and cute to
> show off to guests), doesn't do what a true full featured transmission
> monitoring tool *should* do, especially for RTTY and AM, and especially for
> its price. I can do most of what it does with a chunk of wire and any
> o'scope.
>
>
>
> Am I out of line with my expectation?  Are these features in the works for
> a future software update?  If not, they should be!
>
>
>
> Lu Romero - W4LT
>
> K-Line
>
>
>
>
>
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Re: [Elecraft] P3 TX Mon: FEATURE REQUEST - Monitoring of RTTY Waveform

[Grant Youngman]

But certainly it isn't necessary to wait around for Elecraft to provide. There 
are all kinds of tried and true and well documented ways to do all of the 
things.  

We've apparently come to the point where we expect our radio vendor to do 
EVERYTHING for us, instead if just doing it for ourselves. Why does our radio 
have to do all of it?  It isn't always just a few more lines of code, after 
all. 

So E'craft doesn't provide a trapezoid or RTTY cross display or turn on the 
coffee pot?  So?

Grant NQ5T
Just feeling contrary -- as usual ;)

Sent from my iPhone

> On Sep 13, 2015, at 6:05 PM, Al Gulseth  wrote:
> 
> Lu,
> 
> Without addressing what any hardware/software changes needed might entail, 
> I'd 
> say that you are _not_ "out of line with [your] expectation" 
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