strange complementary pair...

[Kevin Aylward]

wrote in message news:h45ikfh1r2jtd2hhkfo1inv6l5vqim11nt@4ax.com...

On Fri, 28 Aug 2020 07:32:25 +0100, \"Kevin Aylward\"
<kevinRemovAT@kevinaylward.co.uk> wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prljl4ihrgee7mc7d8jh9@4ax.com...

On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncmi09km6789riupttuq@4ax.com...


Or think you do.

It surprises me how many people can\'t.

Some people invent stuff which is novel enough to patent. John
Larkin
doesn\'t seem to be one of them.

I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).


if it takes so long to make that the patent is expired before it is
done
why bother



Right. As people copy your designs, just stay a generation ahead.

Designing is fun. Patent applications aren\'t fun.

I agree. Patent applications are stunningly daunting.

.>.. as it happens... recently been notified that my first ever 2
patent
applications have been granted...

The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...

...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...

Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!

Since it\'s patented, please tell us how it works!

So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...

The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.

A diff pair can only take about 50mV max whatever the gain control tail
current does.

Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.

Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.

Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.

The 1st application actually got rejected, not surprisingly, the idea of
using S curves to compensate processes had already been
patented...However very surprisingly, our man reworked it to make it
more specific and bobs your uncle....

For me, what is significant is that.....

Usually, top brass pass down the chain decide what they want to produce,
and the surfs churn the handle for them.

In this case, I was pondering the problem of poor yields due to the
variability of the xtals and the knowledge of Gilberts technique popped
up in my noggin as a solution. I explained the idea to my local work
mates, we did some simulations with real xtal data and tanh() in Excel
and convinced ourselves that it would work. We presented the idea to top
brass and they said go ahead, make a test ASIC. Although a few teething
issues with the ASIC, it worked well enough to prove the concept worked.

So, this is a method that should give at least a 5 times improvment in
temperature stability, yet originated from a surf with no remit....

Well, get out the serfboard and celebrate.

That\'s a cute technique, thanks. My underwater projects are always the
best too.

Cheers

Phil Hobbs

Given that you can approximate a function out of N piecewise segments
of arbitrary length and slope, is there a process to locate the
segment endpoints for minimum (peak or RMS maybe) error? I usually do
it by eyeball but there must be a better way.

Yes. There is. The \"piecewise\" bit was a key issue being solved though. One
needs a smooth transition to get a low dV/dT slope. The slope error is
typically more of a problem for the frequency stability that the actual
stability itself

Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).

Exactly. The blocks have programmable slope, offsets and max current, with
polarity.

One uses the solver in Excel!

One constructs a table with the data of the curve that is to be
compensated.
Then construct a sum of tanh() functions with co-efficients

A_n.tanh(B_n.T+C_n)

One tells Excel to find the best co-efficients that minimises the summed
squared error of the original function and the approximating function.

Its really simple. One just selects the co-efficients to be varied and
Excel
just churns out the answer. No math knowledge is required at all.

It practice, one actually uses measured data tables from the blocks. It
doesn\'t actually matter what the exact shape is so long as it is S like.

That\'s all cool, but the obvious question is, why not do this
digitally, with a lookup table and a DAC? It could be clocked at 1 Hz
or something.

It would be fun to take a conventional uP and clock it *really* slow.
Run at micro-MIPS.

Knew that was coming

Yeah... it has been considered... several times....stunningly difficult to
to this digitally within the noise and current constraints.

The target is of the order of -175 dBc flatband phase noise, -85 dBc close
in . Any on board processing generates switching noise all over the place
just for starters. 10 nV/rthz on a supply is a problem. Step changes in
frequency are disastrous, so the DAC output can\'t wiggle about much. 1uv at
1Hz on the vcxo line is a problem thus with a 1V full scale the A/D and DAC
needs 20 bits at least, realistically 24 bits. Analog has \"infinite\"
resolution...

MEMS oscillators do do it all digitally, so its not entirely hopeless. They
use two oscillators next to each other. One with a deliberate large
temperature coefficient. The difference in frequency gets you temperature.
No A/D needed, just a counter.

Memory lifetime is a also a problem... telecoms stuff specs 10 to 20 year
lifetimes. We use fuse blown rom. Typically only need a few hundred bits,
not bytes.




-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

 

[Kevin Aylward]

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prljl4ihrgee7mc7d8jh9@4ax.com...

On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncmi09km6789riupttuq@4ax.com...


Or think you do.

It surprises me how many people can\'t.

Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.

I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).


if it takes so long to make that the patent is expired before it is
done
why bother



Right. As people copy your designs, just stay a generation ahead.

Designing is fun. Patent applications aren\'t fun.

I agree. Patent applications are stunningly daunting.

.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...

The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...

...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...

Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!

Since it\'s patented, please tell us how it works!

So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...

The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.

A diff pair can only take about 50mV max whatever the gain control tail
current does.

Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.

Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.

Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.

.... this idea of pinching ideas where they were used elsewhere for different
purposes is not uncommon

Mary Quant on her introduction of a clothing style to the masses:

\"I peeked through the glass I saw a tap-dancing class take place, and in the
middle of the room, a girl a couple of years older than me who was the
vision of everything I wanted to be,” Quant told The Week. “She was wearing
a short pleated skirt about 10in long, with a skinny black sweater, black
tights and a bob haircut. What struck me was how the whole outfit focused on
what she had on her feet: a pair of white ankle socks, and a pair of patent
tap shoes with ankle straps … From that day on I was struck with this lovely
vision of legs and ankles.”

https://www.bbc.com/culture/article/20140523-short-but-sweet-the-miniskirt

..and how fortunate such an observation was made......

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

 

[Bill Sloman]

On Friday, August 28, 2020 at 4:32:38 PM UTC+10, Kevin Aylward wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prlj...@4ax.com...
On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4h...@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinR...@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncm...@4ax.com...

<snip>

Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).
Exactly. The blocks have programmable slope, offsets and max current, with
polarity.

One uses the solver in Excel!

One constructs a table with the data of the curve that is to be compensated.
Then construct a sum of tanh() functions with co-efficients

A_n.tanh(B_n.T+C_n)

One tells Excel to find the best co-efficients that minimises the summed
squared error of the original function and the approximating function.

Its really simple. One just selects the co-efficients to be varied and Excel
just churns out the answer. No math knowledge is required at all.

It practice, one actually uses measured data tables from the blocks. It
doesn\'t actually matter what the exact shape is so long as it is S like.

There are more sophisticated methods for getting the best possible curve fit for a number of parameters when the curve position is a non-linear function of each of the parameters.

http://www.lassp.cornell.edu/sethna/pubPDF/ChallengingFits.pdf

https://en.wikipedia.org/wiki/Non-linear_least_squares

I got exposed to the Marquardt algorithm when I was doing my Ph.D. For my problem the Fletcher-Powell approach worked better, and I ended up coding it for myself - in Fortran 4.

I had the advantage that I could work out (and sum) the derivatives of the least squares sum against each parameters at the same time as I was numerically integrating the function I was trying to fit to the data, so the process of numerically estimating the second derivatives was a bit more accurate than it might have been.

You will have a lot more parameters than I had (three - with a brief and unsuccessful excursion into four) but most of your won\'t make any difference over most of the curve, so you shouldn\'t have lot of trouble with parameter interaction - where the best fit for one depends heavily on all the others.. Marquardt seemed to work better for lots of parameters - my tutor from Theory of Computation 1 had written his M.Sc. on the subject, and that was what I got from it when I got to read it back then.

--
Bill Sloman, Sydney

 

[Kevin Aylward]

\"Bill Sloman\" wrote in message
news:ac3f8258-bd2c-49ae-9730-5f20d34eecbcn@googlegroups.com...

On Friday, August 28, 2020 at 4:32:38 PM UTC+10, Kevin Aylward wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prlj...@4ax.com...
On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net>> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4h...@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinR...@kevinaylward.co.uk>> wrote:

wrote in message news9eakftpajnd1lncm...@4ax.com...

<snip>>

Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).
Exactly. The blocks have programmable slope, offsets and max current,
with
polarity.

One uses the solver in Excel!

One constructs a table with the data of the curve that is to be
compensated.
Then construct a sum of tanh() functions with co-efficients

A_n.tanh(B_n.T+C_n)

One tells Excel to find the best co-efficients that minimises the summed
squared error of the original function and the approximating function.

Its really simple. One just selects the co-efficients to be varied and
Excel
just churns out the answer. No math knowledge is required at all.

It practice, one actually uses measured data tables from the blocks. It
doesn\'t actually matter what the exact shape is so long as it is S like.

There are more sophisticated methods for getting the best possible curve
fit for a number of parameters when the curve position is a non-linear
function >of each of the parameters.

http://www.lassp.cornell.edu/sethna/pubPDF/ChallengingFits.pdf

https://en.wikipedia.org/wiki/Non-linear_least_squares

I got exposed to the Marquardt algorithm when I was doing my Ph.D. For my
problem the Fletcher-Powell approach worked better, and I ended up coding
it >for myself - in Fortran 4.

I had the advantage that I could work out (and sum) the derivatives of the
least squares sum against each parameters at the same time as I was
numerically integrating the function I was trying to fit to the data, so
the process of numerically estimating the second derivatives was a bit
more >accurate than it might have been.

You will have a lot more parameters than I had (three - with a brief and
unsuccessful excursion into four) but most of your won\'t make any
difference over >most of the curve, so you shouldn\'t have lot of trouble
with parameter interaction - where the best fit for one depends heavily on
all the others. Marquardt >seemed to work better for lots of parameters -
my tutor from Theory of Computation 1 had written his M.Sc. on the subject,
and that was what I got from >it when I got to read it back then.

Well... in the real analog hardware world... there are too many other
limitation, blemisihes and long term drift issues that negate the utility of
any higher accuracy. 10 bits to set the parameter values are also a major
hardware hit is a blown fuse memory. In this case the parameters, by
specific design, are constant, that is independent of the variables being
modelled.

The initial core xtal temperature variation of around +/-20 ppm is
compensated by chebys to around 50 ppb. The xtal wiggles on top of that at
around 200 ppb or so. The goal is get the wiggles down by a factor of 10.
This means an overall cancelation of the error across temperature of 1000:1.
The next level to the 2 ppb is not really realistic for a non ovenised
oscillator. (1-0.9999) don\'t like to stay that way over time. Ovenised
oscillators would take a raw 50 ppb down to < 0.5 ppb much more reliably.
However, they take a lot of power.

In Excel one can use any error function. I tried a few, such as minimising
the absolute error and so on. Don\'t make any relevant difference though.


-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

 

[Bill Sloman]

On Sunday, August 30, 2020 at 5:26:13 PM UTC+10, Kevin Aylward wrote:

\"Bill Sloman\" wrote in message
news:ac3f8258-bd2c-49ae...@googlegroups.com...
On Friday, August 28, 2020 at 4:32:38 PM UTC+10, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:5b5gkf5m98m00prlj...@4ax.com...
On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net>> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4h...@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinR...@kevinaylward.co.uk>> wrote:

wrote in message news9eakftpajnd1lncm...@4ax.com...

snip

Overlapped TANHs is cute. One could slide them around (offset) and
adjust their slopes (tail currents).
Exactly. The blocks have programmable slope, offsets and max current,
with
polarity.

One uses the solver in Excel!

One constructs a table with the data of the curve that is to be
compensated.
Then construct a sum of tanh() functions with co-efficients

A_n.tanh(B_n.T+C_n)

One tells Excel to find the best co-efficients that minimises the summed
squared error of the original function and the approximating function.

Its really simple. One just selects the co-efficients to be varied and
Excel
just churns out the answer. No math knowledge is required at all.

It practice, one actually uses measured data tables from the blocks. It
doesn\'t actually matter what the exact shape is so long as it is S like.

There are more sophisticated methods for getting the best possible curve
fit for a number of parameters when the curve position is a non-linear
function >of each of the parameters.

http://www.lassp.cornell.edu/sethna/pubPDF/ChallengingFits.pdf

https://en.wikipedia.org/wiki/Non-linear_least_squares

I got exposed to the Marquardt algorithm when I was doing my Ph.D. For my
problem the Fletcher-Powell approach worked better, and I ended up coding
it >for myself - in Fortran 4.

I had the advantage that I could work out (and sum) the derivatives of the
least squares sum against each parameters at the same time as I was
numerically integrating the function I was trying to fit to the data, so
the process of numerically estimating the second derivatives was a bit
more accurate than it might have been.

You will have a lot more parameters than I had (three - with a brief and
unsuccessful excursion into four) but most of your won\'t make any
difference over most of the curve, so you shouldn\'t have lot of trouble
with parameter interaction - where the best fit for one depends heavily on
all the others. Marquardt seemed to work better for lots of parameters -
my tutor from Theory of Computation 1 had written his M.Sc. on the subject,
and that was what I got from it when I got to read it back then.

Well... in the real analog hardware world... there are too many other
limitation, blemisihes and long term drift issues that negate the utility of
any higher accuracy.

It\'s not so much a question of higher accuracy as having a procedure that does the job properly.

The Excel Solver function seems to employ a \"Generalized Reduced Gradient (GRG) Nonlinear\" approach, whatever that means. Multi-parameter nonlinear regression mostly seems to involves setting up a multidimensional goodness-of-fit surface and sliding down it to a local minimum, for which you do need gradients - first derivative against each parameter - and second derivatives against each pair of parameters.

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

This evil test problem generates a \"banana valley\" where there are lot of pairs of parameters that give you a respectable fit, and a good minimiser will track straight along the bottom of the valley to find the pair of parameter values that give you the best fit. Bad optimisers zig-zag across the valley and get very confused when they get to the point where valley bends, which means they need a lot more iterations.

Clearly Excel works well enough for your purposes, but it doesn\'t look as if you know how it works. This is risky.

<snip>

In Excel one can use any error function. I tried a few, such as minimising
the absolute error and so on. Don\'t make any relevant difference though.

Minimising the root mean square deviation is widely popular, not least because it avoids nasty discontinuities. The fact that you could get away with minimising the absolute error does suggests that whatever Excel Solver is doing is fairly crude and unsophisticated.

--
Bill Sloman, Sydney

 

[John Larkin]

On Sat, 29 Aug 2020 16:34:25 +0100, \"Kevin Aylward\"
<kevinRemovAT@kevinaylward.co.uk> wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prljl4ihrgee7mc7d8jh9@4ax.com...

On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncmi09km6789riupttuq@4ax.com...


Or think you do.

It surprises me how many people can\'t.

Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.

I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).


if it takes so long to make that the patent is expired before it is
done
why bother



Right. As people copy your designs, just stay a generation ahead.

Designing is fun. Patent applications aren\'t fun.

I agree. Patent applications are stunningly daunting.

.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...

The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...

...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...

Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!

Since it\'s patented, please tell us how it works!

So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...

The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.

A diff pair can only take about 50mV max whatever the gain control tail
current does.

Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.

Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.

Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.


... this idea of pinching ideas where they were used elsewhere for different
purposes is not uncommon

Mary Quant on her introduction of a clothing style to the masses:

\"I peeked through the glass I saw a tap-dancing class take place, and in the
middle of the room, a girl a couple of years older than me who was the
vision of everything I wanted to be,” Quant told The Week. “She was wearing
a short pleated skirt about 10in long, with a skinny black sweater, black
tights and a bob haircut. What struck me was how the whole outfit focused on
what she had on her feet: a pair of white ankle socks, and a pair of patent
tap shoes with ankle straps … From that day on I was struck with this lovely
vision of legs and ankles.”

https://www.bbc.com/culture/article/20140523-short-but-sweet-the-miniskirt

.and how fortunate such an observation was made......

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

Physical beauty is grossly unfair, but its appreciation is immensely
powerful and hardwired into us. Fortunately tastes vary, so most of us
are able to find someone who finds us attractive.

I\'ve always wondered why humans have such radical extremes of beauty.
Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

 

[legg]

On Sun, 23 Aug 2020 14:18:32 -0700, jlarkin@highlandsniptechnology.com
wrote:

I think this works:

https://www.dropbox.com/s/sry0g1t9jmx6wvb/Depl_Follower.jpg?raw=1

Cryptomnesia

RL

 

[whit3rd]

On Monday, August 31, 2020 at 11:37:42 AM UTC-7, John Larkin wrote:

Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Oh, in birds, certainly; birds-of-paradise have some amazing plumage
(so attractive, that it\'s illegal to hunt them, or keep the feathers,
because the New Guinea natives want to conserve the critters).

Why the BIRDS find them attractive, I don\'t know.
Peacocks, too, have a lot of feathers that aren\'t good for anything
except display. Peahens presumably care...

 

[Phil Hobbs]

On 2020-08-31 14:37, John Larkin wrote:

On Sat, 29 Aug 2020 16:34:25 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prljl4ihrgee7mc7d8jh9@4ax.com...

On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4hpfsjdla0i7ol6r1o9@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinRemovAT@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncmi09km6789riupttuq@4ax.com...


Or think you do.

It surprises me how many people can\'t.

Some people invent stuff which is novel enough to patent. John Larkin
doesn\'t seem to be one of them.

I\'m looking forward to him inventing my current mirror variation on
Baxandall\'s class-D oscillator (which nobody has bothered to
patent, but
I\'ve not >seen anywhere either).


if it takes so long to make that the patent is expired before it is
done
why bother



Right. As people copy your designs, just stay a generation ahead.

Designing is fun. Patent applications aren\'t fun.

I agree. Patent applications are stunningly daunting.

.>.. as it happens... recently been notified that my first ever 2 patent
applications have been granted...

The fortunate bit is that I did practically nothing in the whole
application
process... the company has a dedicated guy to do that...

...yes... unfortunately... until recently I have not been clever
another to
find an existing idea to copy and rework it for a new purpose until
now...

Its actually one of real value. Typically TCXOs can get temperature
compensated to around 100 ppb to 300 ppb due to multiple
perturbations in
the crystal. This technique allows one to get a 10 times better post
compensation. The first prototype asic actually worked!

Since it\'s patented, please tell us how it works!

So.... Barrie Gilbert wrote papers in the 70s of how to linearize a
differential gain controlled amp...

The standard problem to be solved is having a very low noise front end
gain controlled amp that is linear but with a wide input range. A full
gilbert cell (input diodes) itself adds a fair bit of noise . A typical
application is to do variable tuned, narrowband RF channel filtering
digitally, e.g. mobile phones, which is pretty much impossible to do in
analog. The input range being uVs to 100s mv. If the input distorts, the
digital filtering wont work.

A diff pair can only take about 50mV max whatever the gain control tail
current does.

Gilberts\'s idea is to use several diff stages in parallel but with
different offset voltages. Thus forming an offset sum of tanh()
functions. As the gain of one drops off, another takes over. I have a SS
example... somewhere.

Now... xtals have up and down frequency shifts (100 ppbs) with
temperature, all different from unit to unit, sitting on top of a main
3rd order chebychev 20 ppm shape. We use up to 4th order chebys for the
main compensation, but to compensate these wiggles is not practicable
with more chebys. The inflection points are all over the place.

Thus I realised that I could pinch the idea to use the offset diff pairs
to form summed tanh() correction curves to take out the xtal wobbles.


... this idea of pinching ideas where they were used elsewhere for different
purposes is not uncommon

Mary Quant on her introduction of a clothing style to the masses:

\"I peeked through the glass I saw a tap-dancing class take place, and in the
middle of the room, a girl a couple of years older than me who was the
vision of everything I wanted to be,” Quant told The Week. “She was wearing
a short pleated skirt about 10in long, with a skinny black sweater, black
tights and a bob haircut. What struck me was how the whole outfit focused on
what she had on her feet: a pair of white ankle socks, and a pair of patent
tap shoes with ankle straps … From that day on I was struck with this lovely
vision of legs and ankles.”

https://www.bbc.com/culture/article/20140523-short-but-sweet-the-miniskirt

.and how fortunate such an observation was made......

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

Physical beauty is grossly unfair, but its appreciation is immensely
powerful and hardwired into us. Fortunately tastes vary, so most of us
are able to find someone who finds us attractive.

I\'ve always wondered why humans have such radical extremes of beauty.
Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Because human beings, made in the image of God, can appreciate the Good,
the True, and the Beautiful. (None of which are really in the eye,
mind, or heart of the beholder.) Ask Aristotle next time he stops by
for a brewski.

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

 

[Clifford Heath]

On 1/9/20 4:37 am, John Larkin wrote:

Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Here\'s one for you:
<https://www.theguardian.com/uk-news/2020/aug/28/worlds-most-expensive-sheep-sold-in-scotland-for-367k-double-diamond>

CH

 

[Lasse Langwadt Christensen]

tirsdag den 1. september 2020 kl. 00.43.59 UTC+2 skrev Clifford Heath:

On 1/9/20 4:37 am, John Larkin wrote:
Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Here\'s one for you:
https://www.theguardian.com/uk-news/2020/aug/28/worlds-most-expensive-sheep-sold-in-scotland-for-367k-double-diamond

but that is the human \"valuation\" do the sheeps agree?

 

[Clifford Heath]

On 1/9/20 9:02 am, Lasse Langwadt Christensen wrote:

tirsdag den 1. september 2020 kl. 00.43.59 UTC+2 skrev Clifford Heath:
On 1/9/20 4:37 am, John Larkin wrote:
Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Here\'s one for you:
https://www.theguardian.com/uk-news/2020/aug/28/worlds-most-expensive-sheep-sold-in-scotland-for-367k-double-diamond
but that is the human \"valuation\" do the sheeps agree?

I wondered that at first, but ewes don\'t get consulted in the matter.
Rams pretty-much have a policy of \"if it moves, fight it or fuck it\".

 

[Bill Sloman]

On Tuesday, September 1, 2020 at 8:19:50 AM UTC+10, Phil Hobbs wrote:

On 2020-08-31 14:37, John Larkin wrote:
On Sat, 29 Aug 2020 16:34:25 +0100, \"Kevin Aylward\"
kevinR...@kevinaylward.co.uk> wrote:

\"John Larkin\" wrote in message
news:5b5gkf5m98m00prlj...@4ax.com...

On Thu, 27 Aug 2020 15:57:40 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

On 2020-08-27 15:42, Kevin Aylward wrote:
\"John Larkin\" wrote in message
news:4qvfkfl9c10o4ca4h...@4ax.com...

On Thu, 27 Aug 2020 19:40:15 +0100, \"Kevin Aylward\"
kevinR...@kevinaylward.co.uk> wrote:

wrote in message news9eakftpajnd1lncm...@4ax.com...

<snip>

I\'ve always wondered why humans have such radical extremes of beauty.
Are there superstar-level beautiful individuals among cows or birds or
worms? And do they have wild swings in what is considered beautiful
and stylish?

Because human beings, made in the image of God, can appreciate the Good,
the True, and the Beautiful. (None of which are really in the eye,
mind, or heart of the beholder.) Ask Aristotle next time he stops by
for a brewski.

There are more recent, and more useful, opinions on the subject, none of which depend on Platonic ideals.

https://qz.com/487424/an-interactive-tool-that-lets-you-average-faces-together-shows-a-surprising-concept-behind-the-science-of-beauty/

There are wild swings in what is considered stylish - style is just a device that lets you show that you care about how people perceive you.

Historical art shows that being plump was considered more attractive in a woman back when it was harder to get enough to eat.

Scrawny women still don\'t ovulate - and still aren\'t seen as attractive - but it\'s lot less important today to have fat reserves against a hard winter.

--
Bill Sloman, Sydney