The truth about decibels

Genome wrote:
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:_Ezxe.61547$Vo6.42011@fe3.news.blueyonder.co.uk...
Guy Macon wrote:
Robert wrote:

Kevin Aylward wrote...

John Perry wrote:

In fact, twisted pair is around 100 ohms from DC to microwave,

Ahmmm...

Zo = sqrt((R+jwL)/(G+jwC))

at w=0, i.e. DC, its:

Zo=sqrt(R/G)

DC conductance, i.e. leakage resistance, is essential 0. So, at DC
, the impedance is, essentially, infinite.

Why anyone should think a bit of cable at DC has a 100 ohm
impedance is quite beyond me. Batteries wouldnt last very long if
cables were so bloody dreadful.

Kevin Aylward

Two straight pieces of wire have infinite Impedance at DC? If you
hook them to a car battery and shorted the other ends, no current
would flow?

I suspect reality would contradict your formula and the wires
(normal, not huge) would melt.

Aylward makes a common error among those who have failed to grasp
the true nature of the physical system they are discussing.

Here we go again. Ignorant individuals being unaware of such
ignorance..

{drivil sniped}


Those of us who have been doing this for many years will remember
that the older term for characteristic impedance was surge
impedance.

Pay attention dude, the characteristic impedance is not the surge
impedance.

If we had kept that term, people like Kevin wouldn't be so confused.

What part of:

Zo = sqrt((R+jwL)/(G+jwC))

did you miss during your 2nd year at university doing your degree?
Oh...that's right, you don't have a degree, that might well explain
it.

Look, mate, the subject is "what is the *characteristic* impedance
of a transmission line at DC". Those of us that are not confused
like you are, can actually substitute in w=0 in the general formula
above and produce the correct answer that said undergraduates, and
probable most other reasonably competent hobbyists can, even if they
don't understand the derivation of such formula.

Plese feel free to reference some accredited text that denies such
formula, as quoted above, is the characteristic impedance of a
transmission line. Now, why don't you go and figure out the
difference between surge impedance and general characteristic
impedance. Hint: it has something to do with the relative values of
R, wL, G, and wC



Stange to say... but, in a previous post Guy stated....

"Guy Macon" <_see.web.page_@_www.guymacon.com_> wrote in message
news:11c33e45vljsr58@corp.supernews.com...



John Perry wrote:

In fact, twisted pair is around 100 ohms from DC to microwave,

Are you sure you don't want to change "DC" to some low AC frequency?
At DC the insulation resistance is a bit higher than 100 Ohms... :)




Is he just contradicting you (er himself) to score points.
Click to expand...
I belive so.

Doesn't appear to have worked.

Anyway I'm plonked and I think you are. You may have plonked me, hey
I don't mind.
Click to expand...
I don't plonk anyone. I have control to not bother reading stuff I
suspect is dubious.

Anyway we are both shouting into empty halls.
Click to expand...
Indeed.

That
means FatBoy Fat can carry on deluding himself.
Click to expand...
Indeed.


Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
"RST Engineering (jw)" wrote:

It has nothing at all to do with your analysis (which I find rather complete
and correct) but a "radar mile" (out and back) is 10.7 microseconds. Just
to pick the flyspecs out of the pepper {;-)
Click to expand...
I make it 11us !

Maybe I was rounding numbers too much ?

Graham
 
Ban wrote:

Fuck it Genome, what a twat. But you fuckn got him by the balls. Maybe you
should take out that SM-outfit and whip him a bit for his hypochrisy.
Click to expand...
Is that a leather or rubber outfit btw ?

Graham
 
Kevin Aylward wrote:

Pooh Bear wrote:

It worked out that standard mic cable has a 110 ohms characteristic
impedance in the MHz region.


But fortunately, its not 110 ohm at DC, otherwise we would have a slight
problem with the phantom power:)
Click to expand...
Indeed ! ;-)

Graham
 
Roger Johansson wrote:
Guy Macon wrote:

Well, yes; in a very real sense, DC does not exist. No DC signal has
the attribute of having a fixed voltage that has been there for an
infinite amount of time and will be there for an infinite amount of
time. All signals that we call "DC" are actually pulses...

DC is a theoretical model, a characterization which we often get close
enough to in practice to have a use for, and a name for.

This quality, direct current, is an asymptote, a value we often get
very near but never fully reach.
http://mathworld.wolfram.com/Asymptote.html

In spite of the fact that we never find absolutely perfect direct
current anywhere we can often use the formulas which assume that DC
exists, like Ohm's law (the DC version of Ohm's law, U=I*R).

A hundred years ago DC meant current flowing only one way.
Today it means a current which doesn't change.

We have learned to use electronic components to build mathematical and
logic models and machines.
Hardware has become theoretical tools.
You need to use other tools for DC and AC, that is the most important
difference for us.
Transformers, for example, work only on signals which change.
Click to expand...
Excellent points.

Given the usage of a hundred years ago, it's interesting that we speak
of "Direct Current" when referring to a voltage source with no load
and no current. I have always been amused by the phrase "The La Brea
Tar Pits" (the the tar pits tar pits), or the ever popular "ATM Machine"
(automated teller machine machine) and "Laser Light" (light amplification
by stimulated emission of radiation light). Now I can add "DC Voltage"
(direct current voltage). It's funny that we never say "Direct Voltage"
or "Alternating Voltage".
 
On Sun, 03 Jul 2005 10:59:01 +0000, Guy Macon wrote:

It's funny that we never say "Direct Voltage"
or "Alternating Voltage".
Click to expand...
Some of us do ...

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)
 
"Guy Macon" <http://www.guymacon.com/> wrote in
message news:11c412ah1g7aac3@corp.supernews.com...
Larry Brasfield wrote:
Guy Macon wrote...
John Perry wrote:

In fact, twisted pair is around 100 ohms from DC to microwave,

Are you sure you don't want to change "DC" to some low AC frequency?
At DC the insulation resistance is a bit higher than 100 Ohms... :)

Cable impedance at DC is a perfectly sensible concept. To measure
it is simple: Apply your Ohm meter to an infinitely long sample of it.

(Homer Simpson voice) D'OH!

As soon as I read the above I realized that you are correct and that
I was assuming a finite cable length.

If I am not mistaken (again), if you spend, say, 10 minutes or less
making your measurement, you cannot distinguish between an infinitely
long cable and one that is a mere 11 light-minutes long.
Click to expand...

I suppose that's right. The cable need only have a 5
minute transit delay, being a little over 3.3 light-minutes
long for most kinds of coax. But that would not be a
DC measurement. I'm not sure whether a true DC
measurement could ever be started. Does DC always
go back to t = -Infinity ?

As for insulation resistance and series resistance, those
define loss but not the impedance. To see that, simply
consider that impedance applies to infinitessimal lengths
of cable, but insulation conductance and series resistance
both approach zero as length approaches zero.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
Guy Macon wrote:

We have learned to use electronic components to build mathematical
and logic models and machines.

Excellent points.
Click to expand...
Thanks. I could have said it in more general terms.

We very often use idealized (mathematical) models in science and
technology. We do it knowing that no model is applicable in its
idealized pure form, we always have to accept limitations like a
certain number range, a certain precision level, the model may only be
applicable under certain conditions, etc..

In spite of all these limitations we use the simple formulas because
they usually give results which are good enough for our purpose.

It often simplifies things to treat the DC part and the AC part
separately because we use different methods for them.

In real life there is only a composed signal, the dividing it up into a
DC and an AC part is a theoretical abstraction which simplifies
design and understanding of electronics circuits.



--
Roger J.
 
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:8eMxe.66173$Vo6.11760@fe3.news.blueyonder.co.uk...
Robert wrote:
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:qxzxe.61511$Vo6.50653@fe3.news.blueyonder.co.uk...
Robert wrote:
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:Zzuxe.59226$Vo6.31925@fe3.news.blueyonder.co.uk...
John Perry wrote:
Pooh Bear (and others) wrote:


In fact, twisted pair is around 100 ohms from DC to microwave,

Ahmmm...


Zo = sqrt((R+jwL)/(G+jwC))

at w=0, i.e. DC, its:

Zo=sqrt(R/G)

DC conductance, i.e. leakage resistance, is essential 0. So, at DC
, the impedance is, essentially, infinite.

Why anyone should think a bit of cable at DC has a 100 ohm
impedance is quite beyond me. Batteries wouldnt last very long if
cables were so bloody dreadful.


Kevin Aylward


Two straight pieces of wire have infinite Impedance at DC?

Of course, ideally.

If you
hook them to a car battery and shorted the other ends, no current
would flow?

Completely irrelevant to the characteristic impedance of a
transmission line.


I suspect reality would contradict your formula and the wires
(normal, not huge) would melt.

Ho hummm.

Do you know what the "characteristic impedance of a line" actually
means? Kevin Aylward

Why yes, I do.


Clerly you dont. The characteristic impedance of a line does not depend on
the line terminating impedance. Therefor you comment on s/c the line has
no relevence. Of course, the input impedance of a line does depend on the
terminating impedance.

Kevin Aylward
Click to expand...
Oh, I don't object to that part of your statement, and I do understand it.
It's the "infinite impedance at DC" part that bothers me. With no current
being drawn when you hook up a DC supply to that line *with* that
characteristic impedance.

But, from reading other posts, it seems to come down to what you mean by
"DC". And what you mean by "hooking up a DC supply to it". And possibly the
length of the line with resistive losses eventually cutting the current to
zero.

<shrug>

Not worth arguing about those kind of points.

Robert
 
Don Bowey wrote:

On 6/29/05 1:29 PM, in article 42C304B5.89046EC4@hotmail.com, "Pooh Bear"
rabbitsfriendsandrelations@hotmail.com> wrote:

Adrian Tuddenham wrote:

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:

tlbs wrote:

Pooh Bear wrote:
1. A measuring system first used in telephony (Martin, W.H., "DeciBel --
the new name for the transmission unit. Bell System Tech. J. January,
1929), where signal loss is a logarithmic function of the cable length.

I have actually read that original paper by Martin. I have also read
another white paper with comments similar to your own, and have tried
(in my own circle of influence) to educate people about the proper use
of the dB.

The relevant 'education' is now adopted by the AES ( Audio Engineering
Society
) who write the standards on this matter. Their standards are adopted by
bodies such as the IEC, ANSI and ISO

From the reference you provided in the "3dB Bandwidth" thread:

http://www.aes.org/publications/standards/courtesy.cfm?ID=9

...it is abundantly clear that the AES does *not* write the standards.
They adopt the standards of the IEC etc. and then publish documents
explaining them to their membership.

The AES is represented on an official basis on the Working Groups.

Are you *certain* of that?
Click to expand...
Yes ! Indeed our own esteemed John Woodgate 'sits' on many of the working groups
as a recognised representative of the AES ( and other bodies ) as I understand it.
He has also represented other professional bodies such as PLASA too. The
Professional Sound and Lighting Association based in the UK. Basically us
'fuckwits' that *do* rock 'n roll concerets. I guess that offends your rarified
1929 Bell Labs concept of what engineers are meant to do and I'm sure you would
disapprove !

http://www.plasa.org/

And of course I was my client company's offficial link with Plasa's Standards
section too !

Talking of which...... John should be back soon. He said he had some important
Standards work that would interrupt his contribution here but I expect he'll be
back soon. I'm sure he said June or July.

I bet the governing body is the AES, and the
Working Groups work under the AES.

The are also *audio specific* standards that the AES develops that are then
formally
adopted by the well known standards bodies. Not the other way round.

The AES "standards" may or may not be adopted by other standards bodies.
Click to expand...
Agreed. If the standards bodies agree that useful work has been done they may well
choose simply to adopt the industry norm. The AES is good at this.

Semantics.

Important, meaningful semantics.

The AES is NOT issuing a "standard" having new definitions. What you
have been saying is NOT CORRECT.

Weasel-word around it all you want, but it won't change the facts.
Click to expand...
Suit yourself. My patience is wearing thin and I really can't be too bothered with
clowns who aren't interest in reality.

Graham
 
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:394ye.17575$d75.11632@fe1.news.blueyonder.co.uk...
Robert wrote:
"Kevin Aylward" <see_website@anasoft.co.uk> wrote in message
news:8eMxe.66173$Vo6.11760@fe3.news.blueyonder.co.uk...
Robert wrote:

Why yes, I do.


Clerly you dont. The characteristic impedance of a line does not
depend on the line terminating impedance. Therefor you comment on
s/c the line has no relevence. Of course, the input impedance of a
line does depend on the terminating impedance.

Kevin Aylward

Oh, I don't object to that part of your statement, and I do
understand it. It's the "infinite impedance at DC" part that bothers
me.

As I noted, at low frequencies

Z0=sqrt(R/G)

The leakage between of plastic covered wires is very, very small, like
na, i.e. G->0, so Zo->oo

With no current being drawn when you hook up a DC supply to that
line *with* that characteristic impedance.

But, from reading other posts, it seems to come down to what you mean
by "DC". And what you mean by "hooking up a DC supply to it". And
possibly the length of the line with resistive losses eventually
cutting the current to zero.

Its not the resistive losses (R series) that make the impedance large, it
because there is no DC leakage current across plastic covered wires!

Kevin Aylward
Click to expand...
Oh, yes. But that doesn't prevent the charge from zipping down the
conductive part of the wire (Impedance *that* way instead of through plastic
covered wires). Which I assume that (was it John's comment?) is covered by
infinitely long wires (transmission line at DC) leading to resistive losses
which eventually adds up and cuts off the current. Or some such.

Bloody Angels dancing on a pin again.

Robert
 
Robert wrote:

Bloody Angels dancing on a pin again.
Click to expand...
(I know it doesn't seem like it, but I will bring this back around
to electronics and physics...

An interesting analogy... What we now use as the prototypical example
of arguing over things that don't matter was once an important issue.

In _Summa Theologica_, St. Thomas Aquinas goes into great depth on the
subject of how immaterial spirit beings (angels) can occupy the same
space at the same time.
See http://www.straightdope.com/classics/a4_132.html

At the time that St. Thomas Aquinas raised his related question, there
were two common views:

[1] Supernatural beings, by definition, are not limited by the laws of
physics or mathematics. Thus angels can occupy the same place at
the same time, and an infinite number of angels can dance on the point
of a needle.

[2] The laws of physics and mathematics, by definition, apply to
everything, including Supernatural beings. Thus angels cannot occupy
the same place at the same time, and a finite number of angels can dance
on the point of a needle.

In the course of analysing this issue, Aquinas came to some conclusions
that are very much applicable to electronics: He divided comparisons done
in language into classes:

[a] *univocal* phrases mean the same thing in all contexts.

*equivocal* phrases have nothing in common in different contexts

[c] *analogical* phrases have some relationship with each other in
different contexts.

So the question is, are our various formulas and theories about
electronics univocal with the actual physical systems, or are they
analogical?
 
On 7/4/05 2:55 AM, in article 11ci1sd4vtbhk24@corp.supernews.com, "Guy
Macon" <http://www.guymacon.com/> wrote:

Robert wrote:

Bloody Angels dancing on a pin again.

(I know it doesn't seem like it, but I will bring this back around
to electronics and physics...

An interesting analogy... What we now use as the prototypical example
of arguing over things that don't matter was once an important issue.

In _Summa Theologica_, St. Thomas Aquinas goes into great depth on the
subject of how immaterial spirit beings (angels) can occupy the same
space at the same time.
See http://www.straightdope.com/classics/a4_132.html

At the time that St. Thomas Aquinas raised his related question, there
were two common views:

[1] Supernatural beings, by definition, are not limited by the laws of
physics or mathematics. Thus angels can occupy the same place at
the same time, and an infinite number of angels can dance on the point
of a needle.

[2] The laws of physics and mathematics, by definition, apply to
everything, including Supernatural beings. Thus angels cannot occupy
the same place at the same time, and a finite number of angels can dance
on the point of a needle.

In the course of analysing this issue, Aquinas came to some conclusions
that are very much applicable to electronics: He divided comparisons done
in language into classes:

[a] *univocal* phrases mean the same thing in all contexts.

*equivocal* phrases have nothing in common in different contexts

[c] *analogical* phrases have some relationship with each other in
different contexts.

So the question is, are our various formulas and theories about
electronics univocal with the actual physical systems, or are they
analogical?
Click to expand...

Or is your question horsepucky?

Yes, that sure put it all back on topic.

I believe one issue is exceedingly simple.: Occasionally some wannabe
intellectual, who is not as bright as his students, wishes to show his
students how bright he is and how lacking they are. So he declares an
utterly useless definition to show they are completely out of touch.

It is much akin to the Emperor's new clothes; who would dare declare it is
not true?

So now, DC is like a God; if it is DC, it always was (constantly on),
unchanging), and always shall be. Otherwise it is something entirely
different.

Post hoc ergo propter hoc, grasshopper, if the faucet on my sink is defined
as a device to dispense water, then it cannot actually be a "faucet" when it
is not immediately dispensing water. We need an additional definition.

Also, if a hammer is a tool to pound nails into that tree-like stuff, then
what is that friggin thing called when it isn't beating nails into
submission? We need an additional definition.

Just maybe, we should weigh the value of dispensed definitions, and if we
find they do not offer *any* useful insight, declare them useless and be
done with it.

Don
 
On Mon, 04 Jul 2005 05:52:49 GMT, "Kevin Aylward"
<see_website@anasoft.co.uk> wrote:


Its this simple mate.

Zo = sqrt((R+jwL)/(G+jwC))

It is *not* Z0 = sqrt(L/C)

The derivation is here http://www.sm.luth.se/~urban/master/Theory/4.html

R, L, C, G in per/M
Click to expand...
Won't any unit length work?


John
 
Guy Macon wrote:

In _Summa Theologica_, St. Thomas Aquinas goes into great depth on the
subject of how immaterial spirit beings (angels) can occupy the same
space at the same time.
See http://www.straightdope.com/classics/a4_132.html
Click to expand...
This is a discussion about dictatorship and other social issues,
disguised as a discussion about physics or theology.

At the time that St. Thomas Aquinas raised his related question, there
were two common views:

[1] Supernatural beings, by definition, are not limited by the laws of
physics or mathematics. Thus angels can occupy the same place at
the same time, and an infinite number of angels can dance on the
point of a needle.
Click to expand...
If there is only space enough for one supernatural being in a room or a
house we need to accept dictatorship as the primary organisation
principle. This is a well known practical problem in the social
context. If the man is the master of his own house, and he has full
control of his woman, his dog, and his children, he is living the
american dream. One dictator per house.
One supernatural being per location.

But this acceptance of dictatorship and inequality between the sexes
disturb us, because it has many negative sides, and we would prefer a
more modern organisation. That is why Thomas ab Aquinas
is talking about this issue.

The laws of physics and mathematics, by definition, apply to
everything, including Supernatural beings. Thus angels cannot occupy
the same place at the same time, and a finite number of angels can
dance on the point of a needle.

In the course of analysing this issue, Aquinas came to some
conclusions that are very much applicable to electronics: He divided
comparisons done in language into classes:

[a] univocal phrases mean the same thing in all contexts.

equivocal phrases have nothing in common in different contexts

[c] analogical phrases have some relationship with each other in
different contexts.

So the question is, are our various formulas and theories about
electronics univocal with the actual physical systems, or are they
analogical?
Click to expand...

The whole human mind is analogical, pattern recognition is the basis of
thinking. A pattern is similar, or nearly identical, but we can never
be sure that it is completely identical to an idea in somebody else's
mind. An orange is a pattern which is spherical, 6-12cm diameter,
orange color, citrus smell.
When I see such an object it activates my model of an orange in my
mind, the thing is connected to an experience, and connected to a word.

Our senses and communication skills are not perfect, and the
intelligence we need to process the input is often occupied by more
important stuff.

The modern view of the world is based on subjective views, agreed upon
through discussion.

We "know" that earth is a planet rotating around the sun, because most
scientists and media people have accepted that view of the world. That
is the real world we have together.

Each of us have a subjective view of the world, and strictly
philosophically we cannot actually be sure that the real world exists.
Kant's "das ding an sich", the thing in itself, the real world, is
never directly experienced by us, we see everything through our senses
and through our earlier experiences.

Theoretical models are often applicable to the real world, within some
limits and with a certain precision. The theoretical models are
analog(ical) to the real world. Not identical.

We can build a clock with rotating arms, following the rotation speed
the earth has around the sun. The clock we build theoretically is
analog to the clock we build mechanically, and that clock moves analog
to the planets movements around the sun.

Our theoretical models are analog to our machines we build, which are
analog to our universe, and we can never be sure of total identity.


--
Roger J.
 
On 7/4/05 11:08 AM, in article xn0e4cs4i3sns9d001@news.sunsite.dk, "Roger
Johansson" <no-email@no.invalid> wrote:

Guy Macon wrote:

In _Summa Theologica_, St. Thomas Aquinas goes into great depth on the
subject of how immaterial spirit beings (angels) can occupy the same
space at the same time.
See http://www.straightdope.com/classics/a4_132.html

This is a discussion about dictatorship and other social issues,
disguised as a discussion about physics or theology.

At the time that St. Thomas Aquinas raised his related question, there
were two common views:

[1] Supernatural beings, by definition, are not limited by the laws of
physics or mathematics. Thus angels can occupy the same place at
the same time, and an infinite number of angels can dance on the
point of a needle.

If there is only space enough for one supernatural being in a room or a
house we need to accept dictatorship as the primary organisation
principle. This is a well known practical problem in the social
context. If the man is the master of his own house, and he has full
control of his woman, his dog, and his children, he is living the
american dream. One dictator per house.
One supernatural being per location.

But this acceptance of dictatorship and inequality between the sexes
disturb us, because it has many negative sides, and we would prefer a
more modern organisation. That is why Thomas ab Aquinas
is talking about this issue.

[2] The laws of physics and mathematics, by definition, apply to
everything, including Supernatural beings. Thus angels cannot occupy
the same place at the same time, and a finite number of angels can
dance on the point of a needle.

In the course of analysing this issue, Aquinas came to some
conclusions that are very much applicable to electronics: He divided
comparisons done in language into classes:

[a] univocal phrases mean the same thing in all contexts.

equivocal phrases have nothing in common in different contexts

[c] analogical phrases have some relationship with each other in
different contexts.

So the question is, are our various formulas and theories about
electronics univocal with the actual physical systems, or are they
analogical?

The whole human mind is analogical, pattern recognition is the basis of
thinking. A pattern is similar, or nearly identical, but we can never
be sure that it is completely identical to an idea in somebody else's
mind. An orange is a pattern which is spherical, 6-12cm diameter,
orange color, citrus smell.
When I see such an object it activates my model of an orange in my
mind, the thing is connected to an experience, and connected to a word.

Our senses and communication skills are not perfect, and the
intelligence we need to process the input is often occupied by more
important stuff.

The modern view of the world is based on subjective views, agreed upon
through discussion.

We "know" that earth is a planet rotating around the sun, because most
scientists and media people have accepted that view of the world. That
is the real world we have together.

Each of us have a subjective view of the world, and strictly
philosophically we cannot actually be sure that the real world exists.
Kant's "das ding an sich", the thing in itself, the real world, is
never directly experienced by us, we see everything through our senses
and through our earlier experiences.

Theoretical models are often applicable to the real world, within some
limits and with a certain precision. The theoretical models are
analog(ical) to the real world. Not identical.

We can build a clock with rotating arms, following the rotation speed
the earth has around the sun. The clock we build theoretically is
analog to the clock we build mechanically, and that clock moves analog
to the planets movements around the sun.

Our theoretical models are analog to our machines we build, which are
analog to our universe, and we can never be sure of total identity.
Click to expand...


Excellent post.

Don
 
John Larkin wrote:
On Mon, 04 Jul 2005 05:52:49 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:



Its this simple mate.

Zo = sqrt((R+jwL)/(G+jwC))

It is *not* Z0 = sqrt(L/C)

The derivation is here
http://www.sm.luth.se/~urban/master/Theory/4.html

R, L, C, G in per/M


Won't any unit length work?
Click to expand...
Smart arse:)


Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
On Mon, 04 Jul 2005 12:25:10 -0700, John Larkin wrote:

On Mon, 04 Jul 2005 18:49:36 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:

John Larkin wrote:
On Mon, 04 Jul 2005 05:52:49 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:



Its this simple mate.

Zo = sqrt((R+jwL)/(G+jwC))

It is *not* Z0 = sqrt(L/C)

The derivation is here
http://www.sm.luth.se/~urban/master/Theory/4.html

R, L, C, G in per/M


Won't any unit length work?



Smart arse:)



No, really, the question was sincere.
Click to expand...

....considering the nut-cases in this thread I agree! Your point was well
taken.

--
Keith
 
John Larkin wrote:
On Mon, 04 Jul 2005 18:49:36 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:

John Larkin wrote:
On Mon, 04 Jul 2005 05:52:49 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:



Its this simple mate.

Zo = sqrt((R+jwL)/(G+jwC))

It is *not* Z0 = sqrt(L/C)

The derivation is here
http://www.sm.luth.se/~urban/master/Theory/4.html

R, L, C, G in per/M


Won't any unit length work?



Smart arse:)



No, really, the question was sincere.
Click to expand...
Well, ok. I thought is was obvious that units are all in the wash. Sure,
I should have said per unit length, but ....

Anyway, meters are the only real lengths, you yanks need to catch up
with the rest of the known universe.


Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
On Tue, 05 Jul 2005 19:28:04 GMT, "Kevin Aylward"
<see_website@anasoft.co.uk> wrote:

John Larkin wrote:
On Mon, 04 Jul 2005 18:49:36 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:

John Larkin wrote:
On Mon, 04 Jul 2005 05:52:49 GMT, "Kevin Aylward"
see_website@anasoft.co.uk> wrote:



Its this simple mate.

Zo = sqrt((R+jwL)/(G+jwC))

It is *not* Z0 = sqrt(L/C)

The derivation is here
http://www.sm.luth.se/~urban/master/Theory/4.html

R, L, C, G in per/M


Won't any unit length work?



Smart arse:)



No, really, the question was sincere.


Well, ok. I thought is was obvious that units are all in the wash. Sure,
I should have said per unit length, but ....

Anyway, meters are the only real lengths, you yanks need to catch up
with the rest of the known universe.
Click to expand...
Are your road signs still in miles? They are in England. You can still
order a pint there, too.

John
 
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