Bit of IQ

J

Jan Panteltje

Guest
There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.


I like to build things in little modules so I can just connect things together for experiments,
just like using pipes in Unix / Linux.

It is working, still a bit of crud in the audio, laptop output audio is not so clear,
ground loops, whatever, no screening whatsoever.

The 90 degrees shifted audio signal goes into my DVB-S modulator:
http://panteltje.com/pub/DVB_S__SSB_modulator_IMG_6976.JPG

All controlled by a Raspberry Pi computer that is again controlled by the laptop via ssh.

Will need to make a switch or break it up into more modules,
so now I can select between DVB-S TV and SSB audio transmit mode.
http://panteltje.com/pub/testing_ssb_modulator_IMG_6967.JPG

You can select double sideband suppressed carrier by using in phase audio signals (short the inputs):
http://panteltje.com/pub/double_sideband_IMG_6964.JPG
or SSB:
http://panteltje.com/pub/single_sidbeand_IMG_6965.JPG
 
On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.
Click to expand...

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Thursday, May 30, 2019 at 10:50:57 AM UTC-4, John Larkin wrote:
On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.
Click to expand...
I guess it's like the phase sequence filter (PSF). That just keeps
wrapping the phase around and around...
The step response (of PSF) is a weird beast.

George h.
--

John Larkin Highland Technology, Inc

lunatic fringe electronics
Click to expand...
 
On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
<jjlarkin@highlandtechnology.com> wrote in
<2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.
Click to expand...

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)
 
On a sunny day (Thu, 30 May 2019 17:25:05 GMT) it happened Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote in <qcp3m4$cfq$1@dont-email.me>:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)
Click to expand...

PS
you can make those test sweeps in Linux with 'sox':

create sweep wave file:
sox -V -r 48000 -c 2 -b 24 -n sweep.wav synth 10 sine 240:2400

continuously play sweep wave file:
while [ 1 ] ; do play sweep.wav ; sleep 1 ; done

or create one tone:
sgen -s 48000 sin 2400

If you look at the xy circle on the scope you will easily see any phase
or amplitude changes.
 
On 30.5.19 20:25, Jan Panteltje wrote:
On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)
Click to expand...

To be causal, the output has to be delayed from the input at
least the time of a quarter wave at the lowest frequency to be
handled, usually longer.

--

-TV
 
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)
Click to expand...

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.
Click to expand...
You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs
Click to expand...

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
Jan Panteltje Lunatic wrote:


There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.


I like to build things in little modules so I can just connect things together for experiments,
just like using pipes in Unix / Linux.

It is working, still a bit of crud in the audio, laptop output audio is not so clear,
ground loops, whatever, no screening whatsoever.

The 90 degrees shifted audio signal goes into my DVB-S modulator:
http://panteltje.com/pub/DVB_S__SSB_modulator_IMG_6976.JPG

All controlled by a Raspberry Pi computer that is again controlled by the laptop via ssh.

Will need to make a switch or break it up into more modules,
so now I can select between DVB-S TV and SSB audio transmit mode.
http://panteltje.com/pub/testing_ssb_modulator_IMG_6967.JPG

You can select double sideband suppressed carrier by using in phase audio signals (short the inputs):
http://panteltje.com/pub/double_sideband_IMG_6964.JPG
or SSB:
http://panteltje.com/pub/single_sidbeand_IMG_6965.JPG
Click to expand...


** None of the links here work for me.

WTF ?


...... Phil
 
On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.
Click to expand...

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Thu, 30 May 2019 18:41:01 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.

Cheers

Phil Hobbs
Click to expand...

One of the things I like about our I/Q box is that it's 100% analog.
That's nice once in a while.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Thursday, May 30, 2019 at 4:46:14 PM UTC-4, Phil Hobbs wrote:
On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.
Click to expand...
Huh, the impulse response... I'll try that next time I'm
testing a lockin. (where I use the PSF... missing a few cycles
in a lockin hardly matters if you're averaging over hundreds. :^)

George H.


Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
Click to expand...
 
On 5/30/19 8:34 PM, John Larkin wrote:
On Thu, 30 May 2019 18:41:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.

Cheers

Phil Hobbs

One of the things I like about our I/Q box is that it's 100% analog.
That's nice once in a while.
Click to expand...

About 50% of our output is all-analogue, but that number is going down a
bit on account of auto-tweaking and interface issues. We really like
the LPC804 and LPC845 Cortex M0+ for low-level stuff. The 804 has a
reasonable amount of FPGA fabric--about the same as a CPLD costing twice
as much, not even counting the M0+ core.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Thursday, May 30, 2019 at 1:46:14 PM UTC-7, Phil Hobbs wrote:
[about 90 degree phase shift]
You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.
Click to expand...

If you're using a narrowband source, an LC tank oscillator for instance,
a low-Z probe (current transformer) on current and high-Z probe (FET follower)
on voltage gives you the two phases. No filter required, no time delay.

The logical problem, is that a wideband source (white noise) has no well-defined
phase until you sample it for a while, then FFT it. Then call the resulting mish-mash
a 'spectrum' for which each frequency has an associated phase. Time delay
is well-defined on a random source, but phase shift isn't.
 
On 30/05/19 23:15, Phil Allison wrote:
Jan Panteltje Lunatic wrote:


There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG
http://panteltje.com/pub/DVB_S__SSB_modulator_IMG_6976.JPG
http://panteltje.com/pub/testing_ssb_modulator_IMG_6967.JPG
http://panteltje.com/pub/double_sideband_IMG_6964.JPG
http://panteltje.com/pub/single_sidbeand_IMG_6965.JPG

** None of the links here work for me.

WTF ?


..... Phil
Click to expand...

All links working OK here (Linux Mint & Pale Moon browser). Are you
getting an error message or just nothing happening?

--

Jeff
 
fredag den 31. maj 2019 kl. 19.55.48 UTC+2 skrev John Larkin:
On Thu, 30 May 2019 22:47:18 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 8:34 PM, John Larkin wrote:
On Thu, 30 May 2019 18:41:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.

Cheers

Phil Hobbs

One of the things I like about our I/Q box is that it's 100% analog.
That's nice once in a while.

About 50% of our output is all-analogue, but that number is going down a
bit on account of auto-tweaking and interface issues. We really like
the LPC804 and LPC845 Cortex M0+ for low-level stuff. The 804 has a
reasonable amount of FPGA fabric--about the same as a CPLD costing twice
as much, not even counting the M0+ core.

Cheers

Phil Hobbs

There's not much logic in that one!

We're about ready to pick a new generation of uPs and FPGAs, and there
are lots of opinions here. I'm leaning towards using ZINQs. We already
use the 7020, a $125 monster with two ARM cores that usually runs
Linux. We need a lower-end part, and I'm thinking Zynq 7007, 400
balls, single 760 MHz ARM core and 23K logic cells. That's under $50
in quantity. Hardware float is nice.
Click to expand...

those prices sound high, you can get a whole board for about that
http://www.myirtech.com/list.asp?id=502
http://www.myirtech.com/list.asp?id=565

they don't have any in stock but LCSC quoted us Zynq 7020 for about half
of the digikey price
 
On Thu, 30 May 2019 20:49:52 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Thursday, May 30, 2019 at 1:46:14 PM UTC-7, Phil Hobbs wrote:
[about 90 degree phase shift]
You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

If you're using a narrowband source, an LC tank oscillator for instance,
a low-Z probe (current transformer) on current and high-Z probe (FET follower)
on voltage gives you the two phases. No filter required, no time delay.

The logical problem, is that a wideband source (white noise) has no well-defined
phase until you sample it for a while, then FFT it. Then call the resulting mish-mash
a 'spectrum' for which each frequency has an associated phase. Time delay
is well-defined on a random source, but phase shift isn't.
Click to expand...

I'm using an RC 45-deg lead into one side of a diff-in multiplier, and
another RC 45 lag into the other. Four parts makes 90 degrees shift
and gain=1. It's pretty good over a modest frequency range.




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Thu, 30 May 2019 22:47:18 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 8:34 PM, John Larkin wrote:
On Thu, 30 May 2019 18:41:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.

Cheers

Phil Hobbs

One of the things I like about our I/Q box is that it's 100% analog.
That's nice once in a while.

About 50% of our output is all-analogue, but that number is going down a
bit on account of auto-tweaking and interface issues. We really like
the LPC804 and LPC845 Cortex M0+ for low-level stuff. The 804 has a
reasonable amount of FPGA fabric--about the same as a CPLD costing twice
as much, not even counting the M0+ core.

Cheers

Phil Hobbs
Click to expand...

There's not much logic in that one!

We're about ready to pick a new generation of uPs and FPGAs, and there
are lots of opinions here. I'm leaning towards using ZINQs. We already
use the 7020, a $125 monster with two ARM cores that usually runs
Linux. We need a lower-end part, and I'm thinking Zynq 7007, 400
balls, single 760 MHz ARM core and 23K logic cells. That's under $50
in quantity. Hardware float is nice.

Some people here favor a soft core CPU inside an FPGA, but that needs
a new tool chain and gobbles valuable FPGA RAM. No hardware FP,
probably.

Lattice and Altera have some low-end SOCs too. We tried to run the
Lattice tools but couldn't get past FlexLM.





--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 5/31/19 1:55 PM, John Larkin wrote:
On Thu, 30 May 2019 22:47:18 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 8:34 PM, John Larkin wrote:
On Thu, 30 May 2019 18:41:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 5:30 PM, John Larkin wrote:
On Thu, 30 May 2019 16:46:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/30/19 4:40 PM, John Larkin wrote:
On Thu, 30 May 2019 17:25:05 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Thu, 30 May 2019 07:50:49 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
2brveelifcvcon0lbjbbstjejtsubbsj9m@4ax.com>:

On Thu, 30 May 2019 13:27:19 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

There is a very old way to generate SSB using
90 degrees phase shifted audio and 90 degrees phase shifted RF.

Found old circuit on the web for 90 degrees audio phase shift,
modified it a bit:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_circuit_diagram_IMG_6958.JPG
1% capacitors, and 1% resistors made with trimpots:
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_top_view_IMG_6962.JPG
http://panteltje.com/pub/audio_90_degrees_phase_shifter_PCB_bottom_view_IMG_6960.JPG

Stereo or mono in, + and - 45 phase shifted audio out.

That circuit, with design tables, is in the Williams filter book.
Unfortunately, the outputs differ by 90 degrees but are not +-45
relative to the input. They squirm all over the place.

Yes, it shifts a bit, but for audio it makes litte difference I think.
Nice circles on the analog scope :)

For audio, or SSB generation, absolute phase doesn't matter. We make
an IQ modulator box to simulate eddy-current transducers, and absolute
phase "absolutely" matters.

The box that makes a true wideband 90 degree shift is a Hilbert
transform, which sadly is impossible. It's non-causal, like an ideal
lowpass filter; its output impulse response begins before the input.




You can make narrowband ones that work pretty well. The major problem
with wideband ones is that both the central spike and the long tail of
the impulse response have infinities.

Cheers

Phil Hobbs

Like a lowpass, you can approximate the ideal transfer function, but
it adds delay. That's an oxymoron for a phase shifter.

We could cheat and add a PLL or something to shift our "RF" input,
assuming that a transducer excitation is going to be pretty constant.


Or else calibrate the filter and fix it in software.

Cheers

Phil Hobbs

One of the things I like about our I/Q box is that it's 100% analog.
That's nice once in a while.

About 50% of our output is all-analogue, but that number is going down a
bit on account of auto-tweaking and interface issues. We really like
the LPC804 and LPC845 Cortex M0+ for low-level stuff. The 804 has a
reasonable amount of FPGA fabric--about the same as a CPLD costing twice
as much, not even counting the M0+ core.

Cheers

Phil Hobbs

There's not much logic in that one!
Click to expand...

No, it's just a couple of dozen LUTs, but that's enough to offload some
task that needs hardware timing and is annoying to do with
counter/timers--stuff where several things need to happen with very
consistent timing, and you'd otherwise need external glue logic.

ARM Cortexes have good interrupt timing, but their latency varies a
bit--12 cycles from mainline code, but only 8 from another handler.

The 804 doesn't have that much flash, so you can't use it for super
complicated stuff, but it's a very nice chip for what it is.

We're about ready to pick a new generation of uPs and FPGAs, and there
are lots of opinions here. I'm leaning towards using ZINQs. We already
use the 7020, a $125 monster with two ARM cores that usually runs
Linux. We need a lower-end part, and I'm thinking Zynq 7007, 400
balls, single 760 MHz ARM core and 23K logic cells. That's under $50
in quantity. Hardware float is nice.

Some people here favor a soft core CPU inside an FPGA, but that needs
a new tool chain and gobbles valuable FPGA RAM. No hardware FP,
probably.

Lattice and Altera have some low-end SOCs too. We tried to run the
Lattice tools but couldn't get past FlexLM.
Click to expand...

IIRC there's a full open-source toolchain for Lattice.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
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