Mike Andrews wrote:

In (rec.radio.amateur.homebrew), Tim
Wescott wrote:

Yes, it's pronounced "sink", and it's quite common in signal processing.
You define it as being the _limit_ of sin(x)/x as x - 0 because
otherwise it's undefined at zero, and all the mathematicians in the crowd
will curse at you for being yet another engineer who's treating math so
casually.

That's not precisely true.

Some fraction of us mathematicians wander away, shaking our heads and
muttering "Engineers!" under our breaths.


Reminds me of the old joke about the mathemetician, the physicist and the
engineer. They were each shown into a room in the centre of which was £50
note / $100 bill (depending on which side of the pond you live).

They were told they could walk half the distance to the money and stop.
Then they could walk half the remaining ditance and so on until they got
the money.

The mathemetician worked out you would never reach the money so he didn't
even try. The physicist, working to five decimal places was still there a
week later. The engineer did three iterations, said 'That's close enough'
and picked up the money.

The moral is of course, horses for courses.

Ian

The Hyperbolic Cosine is pronounced Cosh.
The Hyperbolic Sine is pronounced Shine.
The Hyperbolic Tangent is pronounced Than with a soft Th.

At least that's the way I've been doing it for the last 55 years.

They don't seem to come up very often in conversation although they are just
as fundamental in mathematics as are the trigonometrical functions. They
crop up all over the place especially in transmission lines where they
appear in complex form such as Tanh(A+jB).

The Hyperbolic Cosine is pronounced Cosh.
The Hyperbolic Sine is pronounced Shine.
The Hyperbolic Tangent is pronounced Than with a soft Th.

At least that's the way I've been doing it for the last 55 years.

They don't seem to come up very often in conversation although they are just
as fundamental in mathematics as are the trigonometrical functions. They
crop up all over the place especially in transmission lines where they
appear in complex form such as Tanh(A+jB).

In article , "Tim Wescott"
writes:

I've always seen it as 1/x sin(x) "one over ex sine ex". the hyperbolic
sine function sinh is usually pronounced "Cinch"
So how do you pronounce sinc? "Sink ?"

Yes, it's pronounced "sink", and it's quite common in signal processing.
You define it as being the _limit_ of sin(x)/x as x - 0 because otherwise
it's undefined at zero, and all the mathematicians in the crowd will curse
at you for being yet another engineer who's treating math so casually.

Heh heh heh...rememberances of my instructor throughout all math
classes except analytical geometry...same one, who also had
a HOBBY of advanced math. :-)

Instructor always warned everyone NOT to pronounce the apparent
word meaning hyperbolic sine...just say "hyperbolic" before "sine"
but write it "SinC." Someone in the class would object and then
he would write the word for hyperbolic tangent on the board and
challenge him to pronounce "TanH." :-)

Basic algebra texts explain what they are and their identities, but
some want to emulate Professor Higgins in "My Fair Lady"...i.e.,
"...they don't care what they DO, only that they pronounce it
correctly!" :-) :-) :-)

Len Anderson
retired (from regular hours) electronic engineer person

In article , "Tim Wescott"
writes:

I've always seen it as 1/x sin(x) "one over ex sine ex". the hyperbolic
sine function sinh is usually pronounced "Cinch"
So how do you pronounce sinc? "Sink ?"

Yes, it's pronounced "sink", and it's quite common in signal processing.
You define it as being the _limit_ of sin(x)/x as x - 0 because otherwise
it's undefined at zero, and all the mathematicians in the crowd will curse
at you for being yet another engineer who's treating math so casually.

Heh heh heh...rememberances of my instructor throughout all math
classes except analytical geometry...same one, who also had
a HOBBY of advanced math. :-)

Instructor always warned everyone NOT to pronounce the apparent
word meaning hyperbolic sine...just say "hyperbolic" before "sine"
but write it "SinC." Someone in the class would object and then
he would write the word for hyperbolic tangent on the board and
challenge him to pronounce "TanH." :-)

Basic algebra texts explain what they are and their identities, but
some want to emulate Professor Higgins in "My Fair Lady"...i.e.,
"...they don't care what they DO, only that they pronounce it
correctly!" :-) :-) :-)

Len Anderson
retired (from regular hours) electronic engineer person

"Reg Edwards" wrote in message ...
According to Fourier, at some mark-space ratios of a square wave certain
harmonics may be missing from the spectrum.

Just generate a a train of very short sharp pulses from the oscillator and
you will find all the harmonics are present allbeit with reducing
amplitudes. A single transistor should do the job.

The inverse of the duty cycle. For a square wave 1:1 M/S = 1/2 duty
and all harmonics divisble by 2 are absent. For duty 1/5, fifth
harmonic (and multiples)are absent.

"Reg Edwards" wrote in message ...
According to Fourier, at some mark-space ratios of a square wave certain
harmonics may be missing from the spectrum.

Just generate a a train of very short sharp pulses from the oscillator and
you will find all the harmonics are present allbeit with reducing
amplitudes. A single transistor should do the job.

The inverse of the duty cycle. For a square wave 1:1 M/S = 1/2 duty
and all harmonics divisble by 2 are absent. For duty 1/5, fifth
harmonic (and multiples)are absent.

Mike Andrews wrote:
In (rec.radio.amateur.homebrew), Ben Bradley wrote:

In rec.radio.amateur.homebrew,sci.electronics.design, Bob Stephens
wrote:


On Fri, 12 Mar 2004 16:08:15 +0000, John Woodgate wrote:


where sinc(x)= {sin(x)}/x

I've never seen this terminology before. Is this standard math parlance or
is it something of your own?


You can google for it (Usenet or Web) and find it, I've seen it
used a good bit in signal processing and such.


And it shows up in some math classes as well, though its main use is
in electronics. I suspect it showed up because the instructor wanted
to show a real-life example, which just happened to be -- electronics.

And if you want to see the graph of it, look at the Broadcomm logo! 8-)
--
Charlie
--
Edmondson Engineering
Unique Solutions to Unusual Problems

Mike Andrews wrote:
In (rec.radio.amateur.homebrew), Ben Bradley wrote:

In rec.radio.amateur.homebrew,sci.electronics.design, Bob Stephens
wrote:


On Fri, 12 Mar 2004 16:08:15 +0000, John Woodgate wrote:


where sinc(x)= {sin(x)}/x

I've never seen this terminology before. Is this standard math parlance or
is it something of your own?


You can google for it (Usenet or Web) and find it, I've seen it
used a good bit in signal processing and such.


And it shows up in some math classes as well, though its main use is
in electronics. I suspect it showed up because the instructor wanted
to show a real-life example, which just happened to be -- electronics.

And if you want to see the graph of it, look at the Broadcomm logo! 8-)
--
Charlie
--
Edmondson Engineering
Unique Solutions to Unusual Problems

On Fri, 12 Mar 2004 17:57:24 +0000, Paul Burridge
wrote:


Great. So without a spectrum analyser there's no way to tell? If I
examine the output of the multiplier, it's very messy. There's a
dominant 3rd harmonic alright (my frequency counter resolves it
without difficulty) but the scope trace reveals a number of 'ghost
traces' of different frequencies and amplitudes co-incident with the
dominant trace. All rather confusing. I suppose the only answer is to
build Reg's band pass filter and stick it between the inverter output
and the multiplier input? shrug

---
You may want to try something like this:


COUNTER SCOPE COUNTER
| | |
| | |
FIN--[50R]-+-[1N4148]---+----+-------+---FOUT
| |
[L] [C]
| |
GND----------------------+----+

The 50 ohm resistor is the internal impedance of a function generator,
and when I set it to output a square wave at 1.5VPP, I got 10.8kHz for
the fundamental of the tank. Then I tuned the function generator down
until I got a peak out of the tank, and here's what I found:

Fin Fout Vout fout/fin
kHz kHz VPP
-----|-----|------|---------
10.8 10.8 0.9 1.0
3.58 10.8 0.25 3.02 ~ 3
2.14 10.8 0.2 5.05 ~ 5

So with a square wave in there were no even harmonics and it was easy
to trap the 3rd and 5th harmonics with a tank.


Next, I tried it with a 3VPP sine wave in and got:

Fin Fout Vout fout/fin
kHz kHz VPP
-----|-----|------|---------
10.8 10.8 1.3 1.0
5.39 10.8 0.9 ~ 2.0
2.14 10.8 0.3 5.05 ~ 5

So it looks like the second and the fifth harmonics were there. There
were also some other responses farther down, but I just wanted to see
primarily whether the fifth had enough amplitude to work with, and
apparently it does, so I let the rest of it slide.

So, it looks like if you square up your oscillator's output to 50% duty
cycle you could get the 5th harmonic without too much of a problem. If
you can't, then clip the oscillator's output with a diode or make its
duty cycle less than or greater than 50%, and you ought to be able to
get the 5th that way.

--
John Fields