OT: sound speed depends on frequency on mars

[Jan Panteltje]

NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.

paper:
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf

So...
Music from far away may sound funny?

For Mars we will need compensation headphones with distance measurement and variable delays....
;-)

Better use radio.. and earplugs/ headphones...

[john larkin]

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.

https://en.wikipedia.org/wiki/Loading_coil

There used to be millions of 88 mH toroids on the surplus market,
telephone loading coils.

The Mars thing is no big deal. You'd be dead too soon to worry about
acoustics. Imagine Burning Man (literally!) on Mars.

[Bill Sloman]

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly. You can make lumped constant transmission lines
by linking a series of capacitors with discrete inductors, if you want a
high impedance transmission line - people sold them thick film hybrid
assemblies, and I even used a few, a very long time ago.

Post by john larkin
There used to be millions of 88 mH toroids on the surplus market,
telephone loading coils.
The Mars thing is no big deal. You'd be dead too soon to worry about
acoustics. Imagine Burning Man (literally!) on Mars.

Unless you wore a pressure suit. Not exactly the usual music festival
costume, but you'd need to wear one to survive an outdoor concert on Mars.

[john larkin]

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

Most ideas seem silly to people who are by nature hostile to ideas.

Dismissing is easier than thinking.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

[john larkin]

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch. Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.

Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea. I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them. You wouldn't use FR4 around a stripline
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that senstence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a

series >>>> of capacitors with discrete inductors, if you want a high
impedance >>>> transmission line - people sold them as thick film hybrid

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

Back around 1985 we planned on making one of our own when we wanted a
microsecond or so of pure delay on the main signal to synchronise it
with the small second order corrections we were adding in from a couple
of analog multipliers (which had their own propagation delay).

[john larkin]

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them.

Can't you google?


You wouldn't use FR4 around a stripline

Post by Bill Sloman
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Run the Saturn program. More layers make the dielectrics thinner, so
to maintain a useful impedance the traces have to get narrower.

10 layers gets nasty.

Post by Bill Sloman

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Exactly.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that senstence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a

series >>>> of capacitors with discrete inductors, if you want a high
impedance >>>> transmission line - people sold them as thick film hybrid

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Ideas start out fuzzy, or at least they should. I tell my kids, stay
confused for a while.

Post by Bill Sloman

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

The Tek 545 30 MHz scope had a gigantic, lumped, tunable, differential
delay line up to the CRT, so you could see the edge that you triggered
on.

Loading Image...

A lossy pcb trace with periodic loading coils is not a lumped-constant
tx line. In fact, lumped lines are nasty. The number of sections goes
as Td/Tr squared, which can get awkward fast.

Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

[Jeroen Belleman]

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them.

Can't you google?
You wouldn't use FR4 around a stripline

Post by Bill Sloman
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Run the Saturn program. More layers make the dielectrics thinner, so
to maintain a useful impedance the traces have to get narrower.
10 layers gets nasty.

Post by Bill Sloman

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Exactly.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that senstence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a

series >>>> of capacitors with discrete inductors, if you want a high
impedance >>>> transmission line - people sold them as thick film hybrid

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Ideas start out fuzzy, or at least they should. I tell my kids, stay
confused for a while.

Post by Bill Sloman

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

The Tek 545 30 MHz scope had a gigantic, lumped, tunable, differential
delay line up to the CRT, so you could see the edge that you triggered
on.
https://w140.com/tekwiki/images/thumb/1/10/Tek_545a_delay_close.jpg/231px-Tek_545a_delay_close.jpg
A lossy pcb trace with periodic loading coils is not a lumped-constant
tx line. In fact, lumped lines are nasty. The number of sections goes
as Td/Tr squared, which can get awkward fast.
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

In the 1980's we had NIM-format boxes with binary-weighted-length cables
and cheap slide switches, and CAMAC modules with basically the same
cables, but with fancy miniature DPDT relays in metal TO-8 style
packages. Physicists would invariably mess up the relay contacts.

Jeroen Belleman

[john larkin]

On Sat, 31 Aug 2024 22:52:08 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them.

Can't you google?
You wouldn't use FR4 around a stripline

Post by Bill Sloman
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Run the Saturn program. More layers make the dielectrics thinner, so
to maintain a useful impedance the traces have to get narrower.
10 layers gets nasty.

Post by Bill Sloman

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Exactly.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that senstence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a

series >>>> of capacitors with discrete inductors, if you want a high
impedance >>>> transmission line - people sold them as thick film hybrid

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Ideas start out fuzzy, or at least they should. I tell my kids, stay
confused for a while.

Post by Bill Sloman

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

The Tek 545 30 MHz scope had a gigantic, lumped, tunable, differential
delay line up to the CRT, so you could see the edge that you triggered
on.
https://w140.com/tekwiki/images/thumb/1/10/Tek_545a_delay_close.jpg/231px-Tek_545a_delay_close.jpg
A lossy pcb trace with periodic loading coils is not a lumped-constant
tx line. In fact, lumped lines are nasty. The number of sections goes
as Td/Tr squared, which can get awkward fast.
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

In the 1980's we had NIM-format boxes with binary-weighted-length cables
and cheap slide switches, and CAMAC modules with basically the same
cables, but with fancy miniature DPDT relays in metal TO-8 style
packages. Physicists would invariably mess up the relay contacts.
Jeroen Belleman

I was thinking of using the cute little $1 Fujitsu telecom relays,
which are good up to about 3 GHz.

Loading Image...

I don't know if anyone would buy a PoE switched delay line box, but it
would be fun. Isola has some pretty good PCB laminates that aren't
expensive like the exotic Rogers stuff.

I never did any NIM, but we did a bunch of CAMAC. It was a strange
bus, 24 bits of open-drain read data and a separate 24 bits of write
data. Design by physicists!

But the geographical addressing was great. Too bad VME didn't do that.

[Jeroen Belleman]

Post by john larkin
On Sat, 31 Aug 2024 22:52:08 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them.

Can't you google?
You wouldn't use FR4 around a stripline

Post by Bill Sloman
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Run the Saturn program. More layers make the dielectrics thinner, so
to maintain a useful impedance the traces have to get narrower.
10 layers gets nasty.

Post by Bill Sloman

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Exactly.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that senstence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a

series >>>> of capacitors with discrete inductors, if you want a high
impedance >>>> transmission line - people sold them as thick film hybrid

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Ideas start out fuzzy, or at least they should. I tell my kids, stay
confused for a while.

Post by Bill Sloman

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

The Tek 545 30 MHz scope had a gigantic, lumped, tunable, differential
delay line up to the CRT, so you could see the edge that you triggered
on.
https://w140.com/tekwiki/images/thumb/1/10/Tek_545a_delay_close.jpg/231px-Tek_545a_delay_close.jpg
A lossy pcb trace with periodic loading coils is not a lumped-constant
tx line. In fact, lumped lines are nasty. The number of sections goes
as Td/Tr squared, which can get awkward fast.
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

In the 1980's we had NIM-format boxes with binary-weighted-length cables
and cheap slide switches, and CAMAC modules with basically the same
cables, but with fancy miniature DPDT relays in metal TO-8 style
packages. Physicists would invariably mess up the relay contacts.
Jeroen Belleman

I was thinking of using the cute little $1 Fujitsu telecom relays,
which are good up to about 3 GHz.
https://www.dropbox.com/scl/fi/bvcnqnvb4euc7pqw7wzab/DSC06884.JPG?rlkey=q1op81z1bumkfxoq8d5mtzi91&raw=1
I don't know if anyone would buy a PoE switched delay line box, but it
would be fun. Isola has some pretty good PCB laminates that aren't
expensive like the exotic Rogers stuff.
I never did any NIM, but we did a bunch of CAMAC. It was a strange
bus, 24 bits of open-drain read data and a separate 24 bits of write
data. Design by physicists!
But the geographical addressing was great. Too bad VME didn't do that.

The modules I mentioned had coiled-up coax inside. You can't
squeeze much delay into PCB traces. I've come to think of
32ns as a really long time...

I used to spend most of my time with CAMAC in the 1980s, but I
haven't touched it since more than 30 years. It was a weird and
wasteful bus system, but lots of physics experiments used it at
the time.

NIM was simple and stupid. Just a crate with sturdy power supply
connectors in the back, with +/-6, +/-12 and +/-24V supplies.
There was more, but no one ever used that. Crates with lots of
analog would always exceed the current available on the +/-12V,
and for I/O, you were on your own. Other than that, it was handy
because it was everywhere. It's still used at CERN, whereas CAMAC
has vanished. Simple is better.

Jeroen Belleman

[john larkin]

On Sun, 1 Sep 2024 20:37:29 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by john larkin

Post by Jeroen Belleman
In the 1980's we had NIM-format boxes with binary-weighted-length cables
and cheap slide switches, and CAMAC modules with basically the same
cables, but with fancy miniature DPDT relays in metal TO-8 style
packages. Physicists would invariably mess up the relay contacts.
Jeroen Belleman

I was thinking of using the cute little $1 Fujitsu telecom relays,
which are good up to about 3 GHz.
https://www.dropbox.com/scl/fi/bvcnqnvb4euc7pqw7wzab/DSC06884.JPG?rlkey=q1op81z1bumkfxoq8d5mtzi91&raw=1
I don't know if anyone would buy a PoE switched delay line box, but it
would be fun. Isola has some pretty good PCB laminates that aren't
expensive like the exotic Rogers stuff.
I never did any NIM, but we did a bunch of CAMAC. It was a strange
bus, 24 bits of open-drain read data and a separate 24 bits of write
data. Design by physicists!
But the geographical addressing was great. Too bad VME didn't do that.

The modules I mentioned had coiled-up coax inside. You can't
squeeze much delay into PCB traces. I've come to think of
32ns as a really long time...

A delay box could be a hybrid, some coiled-up coaxes and some PCB
wiggle traces.

Post by Jeroen Belleman
I used to spend most of my time with CAMAC in the 1980s, but I
haven't touched it since more than 30 years. It was a weird and
wasteful bus system, but lots of physics experiments used it at
the time.
NIM was simple and stupid. Just a crate with sturdy power supply
connectors in the back, with +/-6, +/-12 and +/-24V supplies.
There was more, but no one ever used that. Crates with lots of
analog would always exceed the current available on the +/-12V,
and for I/O, you were on your own. Other than that, it was handy
because it was everywhere. It's still used at CERN, whereas CAMAC
has vanished. Simple is better.
Jeroen Belleman

We invented this for aerospace test

https://highlandtechnology.com/Category/MPS

but there's no reason it couldn't be a NIM/CAMAC sort of thing, given
the right modules.

PCI/PXI boards don't have the panel space, power, or cooling to do
serious stuff.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s) faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.

I hope you pointed out that buried strip-line isn't dispersive. I have
pointed this out here from time to time.

Of course it's dispersive, maybe a bit less than microstrip.

Why do you think that?

Because dielectrics are imperfect, especially FR4, and because there
are lots of papers online that analyze dispersion in stripline.

But you can't cite any of them.

Can't you google?

Can't you? You know where you found the papers (if you did) and are much
better placed to define the search terms that would throw them up.

Post by john larkin
You wouldn't use FR4 around a stripline

Post by Bill Sloman
if you wanted a low-dispersion transmission line. There are better
substrates his frequency work.

Post by john larkin

Post by Bill Sloman

Post by john larkin
It's hard to keep up decent impedances on stripline in a multilayer
board, especially 8 or 10 layers.

Stripline is buried between two ground planes. The only tricky part of
impedance control is the thickness of the dielectric in the two layers
above and below the strip-line. In a ten layer board this is thinner
than it would be in a board with fewer layers.

And eventually the trace has to be skinnier than PCB houses are
willing to etch.

Why?

Run the Saturn program. More layers make the dielectrics thinner, so
to maintain a useful impedance the traces have to get narrower.

I can do that with a handheld calculator. What you seem, to have missed
is that low dielectric constant substrates give you wider traces for a
given impedance. I got a 150R line on the surface of teflon-alumina
substrate.

Post by john larkin
10 layers gets nasty.

If you don't think about what you are doing.

Post by john larkin

Post by Bill Sloman

Post by john larkin
Standard pricing seems to be around 5 or maybe 4 mils
width these days. We do a lot of 5, to sneak between BGA balls, but
sometimes even 5 is too big.
Thin dielectrics have tolerance issues too. I'm talking about real
PCBs here, not ideal theoretical stuff.

Printed circuit board are always real.

Exactly.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Pay enough for close-tolerance substrates in the two relevant layers and
you should be okay.

"Pay enough" can get crazy fast. I don't want to pay hundreds of
dollars for a smallish PCB.

An eight or ten layer PCB isn't going to be small. You only need lots of
layers when you have to connect lots of stuff.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
https://www.wevolver.com/article/stripline-vs-microstrip

Post by john larkin
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil

It would be a bit silly.

John snipped the rest of that sentence, without marking the snip.

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
You can make lumped constant transmission lines by linking a
series of capacitors with discrete inductors, if you want a high
impedance transmission line - people sold them as thick film hybrid
assemblies, and I even used a few, a very long time ago.

Most ideas seem silly to people who are by nature hostile to ideas.

Not a problem I've got.

Post by john larkin
Dismissing is easier than thinking.

Thinking about what a loading coil might be doing to the impedance of a
PCB trace isn't something that you seem to have managed to do.

I certainly had the idea.

In a remarkably half-baked way.

Ideas start out fuzzy, or at least they should. I tell my kids, stay
confused for a while.

You seem to have chosen to stay confused for decades.

Post by john larkin

Post by Bill Sloman

Post by john larkin
I might Spice a bunch of ltlines with
inductors between, just for fun. It's unlikely that I'd use such an
arrangement in real life, but it's just possible, especially if analog
quality of a fast edge matters, like in a laser modulator maybe. It's
preferable to just keep all the traces very short, but that's not
always possible.

You seem to be intent on re-inventing the lumped constant delay line,
without being aware that they were commercially available some thirty
years ago, back when I used them. They may still be available.

The Tek 545 30 MHz scope had a gigantic, lumped, tunable, differential
delay line up to the CRT, so you could see the edge that you triggered
on.
https://w140.com/tekwiki/images/thumb/1/10/Tek_545a_delay_close.jpg/231px-Tek_545a_delay_close.jpg
A lossy pcb trace with periodic loading coils is not a lumped-constant
tx line.

The discrete loading coils are lumped elements.

Post by john larkin
In fact, lumped lines are nasty. The number of sections goes
as Td/Tr squared, which can get awkward fast.

All true, which doesn't make them any less useful.

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?

https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf

You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

[john larkin]

Post by Bill Sloman

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?
https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf
You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

I've tested that part. It's expensive, drifty, and has an insane
amount of jitter. It's funny that its resolution is "about 10 ps"

Maxim and I think someone else made CMOS programmable delay line
chips, which were equally bad, not to mention discontinued.

We mostly use fast ramps and comparators and DACs to make programmable
delays. Jitter is low and polynomial calibration makes them very
accurate. Cheap too.

Of course I keep inventing things. That's my job.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?
https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf
You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

I've tested that part. It's expensive, drifty, and has an insane
amount of jitter. It's funny that its resolution is "about 10 ps"

It's resolution is about 10psec, because that's the - temperature
dependent - delay through individual delay elements. If you want it to
be more precise, you have to control the part's temperature, or
re-calibrate every few minutes. That's what I was planning to do when I
contemplated using it, and figured that I could get it done within a
millisecond - which did call for a fast A/D. Which one I can't remember
because it was back in 1998.

The RMS random clock jitter is specified on page 10 of the data sheet,
and it's around 1psec which pretty standard for ECL parts - not remotely
insane.

The nice thing about ECL is that it doesn't mess up it's power rails in
the way that CMOS and TTL do, which does get rid of one jitter source.

I once got rid of some nasty sub-nanosecond jitter on a TTL clock by
generating it in ECL (run between 0V and -4.5V) and getting it
out of an ECL-to-TTL converter.

I had expected the ECL-to-TTL converter to be equally susceptible to
noise on the +5V rail, but I was happy to find out that I was wrong.
--
Bill Sloman, Sydney

Post by john larkin
Maxim and I think someone else made CMOS programmable delay line
chips, which were equally bad, not to mention discontinued.

The MC100EP195 and MC100EP196 have been around for thirty years now, and
don't seem to have been discontinued.

Post by john larkin
We mostly use fast ramps and comparators and DACs to make programmable
delays. Jitter is low and polynomial calibration makes them very
accurate. Cheap too.

Been there, done that.

Post by john larkin
Of course I keep inventing things. That's my job.

You'd have to do it less often if you knew more about what was already
available, and were more skilled at reading the datasheets for the
stuff you could buy.

Inventing stuff is fun, but nobody sane does it when they don't have to.

[john larkin]

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?
https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf
You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

I've tested that part. It's expensive, drifty, and has an insane
amount of jitter. It's funny that its resolution is "about 10 ps"

Monotonicity is TBD! It should say "Fat Chance."

Our ramp delay generators are absolutely monotonic.

Post by Bill Sloman
It's resolution is about 10psec, because that's the - temperature
dependent - delay through individual delay elements. If you want it to
be more precise, you have to control the part's temperature, or
re-calibrate every few minutes. That's what I was planning to do when I
contemplated using it, and figured that I could get it done within a
millisecond - which did call for a fast A/D. Which one I can't remember
because it was back in 1998.

Temperature control, and periodic recalibration, are not practical in
a sensible instrument. What do you do if the customer makes a trigger
when you're in the middle of calibrating? Blow up their laser?

We calibrate delay generators in production test, and they work fine
after that.

Post by Bill Sloman
The RMS random clock jitter is specified on page 10 of the data sheet,
and it's around 1psec which pretty standard for ECL parts - not remotely
insane.

I measured a lot more. And the horrible delay tempco is essentially
jitter, as far as a customer is concerned.

Post by Bill Sloman
The nice thing about ECL is that it doesn't mess up it's power rails in
the way that CMOS and TTL do, which does get rid of one jitter source.
I once got rid of some nasty sub-nanosecond jitter on a TTL clock by
generating it in ECL (run between 0V and -4.5V) and getting it
out of an ECL-to-TTL converter.
I had expected the ECL-to-TTL converter to be equally susceptible to
noise on the +5V rail, but I was happy to find out that I was wrong.

The Moto ECL-TTL converters, like the 10H125 or the ELT21, were slow
and expensive and had ghastly jitter. The Arizona Microtek part is
better but still pretty bad.

An LVDS line receiver is cheap and hugely better.

Post by Bill Sloman
--
Bill Sloman, Sydney

Post by john larkin
Maxim and I think someone else made CMOS programmable delay line
chips, which were equally bad, not to mention discontinued.

The MC100EP195 and MC100EP196 have been around for thirty years now, and
don't seem to have been discontinued.

Post by john larkin
We mostly use fast ramps and comparators and DACs to make programmable
delays. Jitter is low and polynomial calibration makes them very
accurate. Cheap too.

Been there, done that.

Post by john larkin
Of course I keep inventing things. That's my job.

You'd have to do it less often if you knew more about what was already
available, and were more skilled at reading the datasheets for the
stuff you could buy.
Inventing stuff is fun, but nobody sane does it when they don't have to.

I never claimed to be sane. Sane is boring. I do claim to design and
sell a lot of electronics.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?
https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf
You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

I've tested that part. It's expensive, drifty, and has an insane
amount of jitter. It's funny that its resolution is "about 10 ps"

Monotonicity is TBD! It should say "Fat Chance."
Our ramp delay generators are absolutely monotonic.

Post by Bill Sloman
It's resolution is about 10psec, because that's the - temperature
dependent - delay through individual delay elements. If you want it to
be more precise, you have to control the part's temperature, or
re-calibrate every few minutes. That's what I was planning to do when I
contemplated using it, and figured that I could get it done within a
millisecond - which did call for a fast A/D. Which one I can't remember
because it was back in 1998.

Temperature control, and periodic recalibration, are not practical in
a sensible instrument. What do you do if the customer makes a trigger
when you're in the middle of calibrating? Blow up their laser?
We calibrate delay generators in production test, and they work fine
after that.

Post by Bill Sloman
The RMS random clock jitter is specified on page 10 of the data sheet,
and it's around 1psec which pretty standard for ECL parts - not remotely
insane.

I measured a lot more. And the horrible delay tempco is essentially
jitter, as far as a customer is concerned.

Post by Bill Sloman
The nice thing about ECL is that it doesn't mess up it's power rails in
the way that CMOS and TTL do, which does get rid of one jitter source.
I once got rid of some nasty sub-nanosecond jitter on a TTL clock by
generating it in ECL (run between 0V and -4.5V) and getting it
out of an ECL-to-TTL converter.
I had expected the ECL-to-TTL converter to be equally susceptible to
noise on the +5V rail, but I was happy to find out that I was wrong.

The Moto ECL-TTL converters, like the 10H125 or the ELT21, were slow
and expensive and had ghastly jitter. The Arizona Microtek part is
better but still pretty bad.

As far as I can remember I used a regular Philips 100K ECL-to-TTL
converter, and it obviously didn't have ghastly jitter. I was careful
about power rail decoupling, and a ham-fisted half-wit could probably
have managed to introduce significant jitter. Ran van Dongen, who had
designed the original almost-all-TTL system, was neither ham-fisted nor
a half-wit, if a bit less ECL-aware than he should have been. He rather
liked what I came up with. I mostly used Motorola ECinPS parts which
hadn't been around when he had designed the original system

ECL is a low volume product, so it isn't cheap, but when you need it it
is worth the money.

Post by john larkin
An LVDS line receiver is cheap and hugely better.

But it doesn't produce a TTL output.

Post by john larkin

Post by Bill Sloman
Inventing stuff is fun, but nobody sane does it when they don't have to.

I never claimed to be sane. Sane is boring. I do claim to design and
sell a lot of electronics.

When in fact you evolve and sell a certain amount of electronics for
niche markets. Your forays into higher volume markets don't seem to have
done well. You are insane enough to think this gives you some kind of
authority.

[john larkin]

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman

Post by john larkin
Meander-line sections connected by loading coils could be interesting.
One product that I'm considering now is a programmable delay line, and
that idea might help.

Like the MC100EP195?
https://www.onsemi.com/pdf/datasheet/mc100ep195-d.pdf
You do seem to spend a lot of time re-inventing the wheel, and
congratulating yourself on the originality of your re-invented concepts.

I've tested that part. It's expensive, drifty, and has an insane
amount of jitter. It's funny that its resolution is "about 10 ps"

Monotonicity is TBD! It should say "Fat Chance."
Our ramp delay generators are absolutely monotonic.

Post by Bill Sloman
It's resolution is about 10psec, because that's the - temperature
dependent - delay through individual delay elements. If you want it to
be more precise, you have to control the part's temperature, or
re-calibrate every few minutes. That's what I was planning to do when I
contemplated using it, and figured that I could get it done within a
millisecond - which did call for a fast A/D. Which one I can't remember
because it was back in 1998.

Temperature control, and periodic recalibration, are not practical in
a sensible instrument. What do you do if the customer makes a trigger
when you're in the middle of calibrating? Blow up their laser?
We calibrate delay generators in production test, and they work fine
after that.

Post by Bill Sloman
The RMS random clock jitter is specified on page 10 of the data sheet,
and it's around 1psec which pretty standard for ECL parts - not remotely
insane.

I measured a lot more. And the horrible delay tempco is essentially
jitter, as far as a customer is concerned.

Post by Bill Sloman
The nice thing about ECL is that it doesn't mess up it's power rails in
the way that CMOS and TTL do, which does get rid of one jitter source.
I once got rid of some nasty sub-nanosecond jitter on a TTL clock by
generating it in ECL (run between 0V and -4.5V) and getting it
out of an ECL-to-TTL converter.
I had expected the ECL-to-TTL converter to be equally susceptible to
noise on the +5V rail, but I was happy to find out that I was wrong.

The Moto ECL-TTL converters, like the 10H125 or the ELT21, were slow
and expensive and had ghastly jitter. The Arizona Microtek part is
better but still pretty bad.

As far as I can remember I used a regular Philips 100K ECL-to-TTL
converter, and it obviously didn't have ghastly jitter. I was careful
about power rail decoupling, and a ham-fisted half-wit could probably
have managed to introduce significant jitter. Ran van Dongen, who had
designed the original almost-all-TTL system, was neither ham-fisted nor
a half-wit, if a bit less ECL-aware than he should have been. He rather
liked what I came up with. I mostly used Motorola ECinPS parts which
hadn't been around when he had designed the original system
ECL is a low volume product, so it isn't cheap, but when you need it it
is worth the money.

Post by john larkin
An LVDS line receiver is cheap and hugely better.

But it doesn't produce a TTL output.

DS90LV012ATMF/NOPB is essentially a fast rrio comparator. Its outputs
swing from ground to Vcc. It costs us 30 cents. If you buy a similar
part that's called a comparator, it costs 5x as much.

Like most cmos rrio gadgets, its offset increases as the common-mode
approaches Vcc, but that's no big deal in a polynomial-calibrated
ramp.

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Inventing stuff is fun, but nobody sane does it when they don't have to.

I never claimed to be sane. Sane is boring. I do claim to design and
sell a lot of electronics.

When in fact you evolve and sell a certain amount of electronics for
niche markets. Your forays into higher volume markets don't seem to have
done well. You are insane enough to think this gives you some kind of
authority.

I mostly like to design electronics because it's fun and keeps me
amused. Better than having a real job. People buying it is a nice side
effect and pays for test equipment and snacks.

Don't you think designing electronics is amusing? I guess not.

[Bill Sloman]

<snip>

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Inventing stuff is fun, but nobody sane does it when they don't have to.

I never claimed to be sane. Sane is boring. I do claim to design and
sell a lot of electronics.

When in fact you evolve and sell a certain amount of electronics for
niche markets. Your forays into higher volume markets don't seem to have
done well. You are insane enough to think this gives you some kind of
authority.

I mostly like to design electronics because it's fun and keeps me
amused. Better than having a real job. People buying it is a nice side
effect and pays for test equipment and snacks.
Don't you think designing electronics is amusing? I guess not.

It's certainly fascinating. Having to toss out lots of solutions and
start over isn't remotely amusing, but that's what it takes to get to a
good design.

It has a lot in common with playing colossal cave

https://en.wikipedia.org/wiki/Colossal_Cave_Adventure

though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

[john larkin]

Post by Bill Sloman
<snip>

Post by john larkin

Post by Bill Sloman

Post by john larkin

Post by Bill Sloman
Inventing stuff is fun, but nobody sane does it when they don't have to.

I never claimed to be sane. Sane is boring. I do claim to design and
sell a lot of electronics.

When in fact you evolve and sell a certain amount of electronics for
niche markets. Your forays into higher volume markets don't seem to have
done well. You are insane enough to think this gives you some kind of
authority.

I mostly like to design electronics because it's fun and keeps me
amused. Better than having a real job. People buying it is a nice side
effect and pays for test equipment and snacks.
Don't you think designing electronics is amusing? I guess not.

It's certainly fascinating. Having to toss out lots of solutions and
start over isn't remotely amusing, but that's what it takes to get to a
good design.

But its is very amusing.

Post by Bill Sloman
It has a lot in common with playing colossal cave
https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

Trying lots of arguably crazy ideas is educational, and has a chance
of stumbling onto something really valuable. But one has to do it
fast, because there's literally a universe of possibilities to
explore.

Exploring Colossal Cave is a good analogy to exploring the electronic
circuit solution space, except the circuit space is much bigger hence
impossible to explore serially.

[Bill Sloman]

<snip>

Post by john larkin

Post by Bill Sloman
It has a lot in common with playing colossal cave
https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

Trying lots of arguably crazy ideas is educational, and has a chance
of stumbling onto something really valuable. But one has to do it
fast, because there's literally a universe of possibilities to
explore.
Exploring Colossal Cave is a good analogy to exploring the electronic
circuit solution space, except the circuit space is much bigger hence
impossible to explore serially.

Serial implies one-dimensional ordering, while Collossal Cave was two
dimensional.

Most circuit problems have a single input and single output, but the
space in between can be as complicated as you like.

If the problem you are trying to solve has conventional solutions, these
can serve as known routes through the territory you need to explore, and
I've had people reject my short-cuts because they didn't understand the
problem clearly enough.

[john larkin]

Post by Bill Sloman
<snip>

Post by john larkin

Post by Bill Sloman
It has a lot in common with playing colossal cave
https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

Trying lots of arguably crazy ideas is educational, and has a chance
of stumbling onto something really valuable. But one has to do it
fast, because there's literally a universe of possibilities to
explore.
Exploring Colossal Cave is a good analogy to exploring the electronic
circuit solution space, except the circuit space is much bigger hence
impossible to explore serially.

Serial implies one-dimensional ordering, while Collossal Cave was two
dimensional.
Most circuit problems have a single input and single output, but the
space in between can be as complicated as you like.

The set of all circuits that can be designed from the Digikey catalog
is past 2-dimensional.

The trick is to use a good search algorithm.

Post by Bill Sloman
If the problem you are trying to solve has conventional solutions, these
can serve as known routes through the territory you need to explore, and
I've had people reject my short-cuts because they didn't understand the
problem clearly enough.

Yes, most people reject unusual solutions for several reasons, one
being jealousy that they couldn't think of it.

Conventional solutions will have lots of competitors, who have to
fight it out by under-bidding one another.

[Bill Sloman]

Post by john larkin

Post by Bill Sloman
<snip>

Post by john larkin

Post by Bill Sloman
It has a lot in common with playing colossal cave
https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

Trying lots of arguably crazy ideas is educational, and has a chance
of stumbling onto something really valuable. But one has to do it
fast, because there's literally a universe of possibilities to
explore.
Exploring Colossal Cave is a good analogy to exploring the electronic
circuit solution space, except the circuit space is much bigger hence
impossible to explore serially.

Serial implies one-dimensional ordering, while Collossal Cave was two
dimensional.
Most circuit problems have a single input and single output, but the
space in between can be as complicated as you like.

The set of all circuits that can be designed from the Digikey catalog
is past 2-dimensional.

Obviously.

Post by john larkin
The trick is to use a good search algorithm.

There isn't one. An algorithm is an explicit step-by-step procedure, and
the process of getting from a client's requirement to a workable design
doesn't seem to have been systematised to that extent.

Post by john larkin

Post by Bill Sloman
If the problem you are trying to solve has conventional solutions, these
can serve as known routes through the territory you need to explore, and
I've had people reject my short-cuts because they didn't understand the
problem clearly enough.

Yes, most people reject unusual solutions for several reasons, one
being jealousy that they couldn't think of it.

I can't say that I've seen that. The example that I had in mind rejected
what I'd proposed because it used a little bit of positive feedback and
that - to him - suggested that it could latch up. It couldn't have and
never did when Honeywell used it a few years later (not that either of
us had anything to do with that).

Post by john larkin
Conventional solutions will have lots of competitors, who have to
fight it out by under-bidding one another.

Obvious solutions tend to get adopted more frequently (which is what
makes them "conventional"). The cheapest acceptable solution does tend
to become an industry standard, and about the only way to under-cut that
kind of competition is by producing the product on a larger scale,
usually in China.

[Bill Sloman]

<snip>

Post by john larkin

Post by Bill Sloman
It has a lot in common with playing colossal cave
https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
though with a computer game you can be confident that there is a
solution, while in real life you may find that you need to move the
goal-posts, or adjust the client's ambitions.

Trying lots of arguably crazy ideas is educational, and has a chance
of stumbling onto something really valuable. But one has to do it
fast, because there's literally a universe of possibilities to
explore.
Exploring Colossal Cave is a good analogy to exploring the electronic
circuit solution space, except the circuit space is much bigger hence
impossible to explore serially.

Serial implies one-dimensional ordering, while Collossal Cave was two
dimensional.

Most circuit problems have a single input and single output, but the
space in between can be as complicated as you like.

If the problem you are trying to solve has conventional solutions, these
can serve as known routes through the territory you need to explore, and
I've had people reject my short-cuts because they didn't understand the
problem clearly enough.

[Jan Panteltje]

On a sunny day (Fri, 30 Aug 2024 07:34:05 -0700) it happened john larkin

Post by john larkin

Post by Jan Panteltje
NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
and behaves in some unexpected ways that could have strange consequences for communication on the planet.
https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough
time to relax, or return to their original state,"
the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s)
faster than the low-frequency ones.
That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you
would hear the lower-pitched ones.
https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
So...
Music from far away may sound funny?
For Mars we will need compensation headphones with distance measurement and variable delays....
;-)
Better use radio.. and earplugs/ headphones...

Funny, I just delivered a lecture on transmission lines and noted that
microstrips have dispersion from the unbalanced dielectric constants
and skin effect. Rising edges get sloppy at the and of a long trace.
I wonder if anyone has added surface-mount Heaviside loading coils to
a PCB trace.
https://en.wikipedia.org/wiki/Loading_coil
There used to be millions of 88 mH toroids on the surplus market,
telephone loading coils.
The Mars thing is no big deal. You'd be dead too soon to worry about
acoustics. Imagine Burning Man (literally!) on Mars.

It may matter for sonar based systems, distance measurements etc..
I have some small sonar based modules in use from ebay, something like these:
https://www.ebay.nl/itm/185960647108