subtr. heterodyne math
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subtr. heterodyne math

 
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Claus Jensen
Guest
Posted: Tue Feb 08, 2005 2:34 am    Post subject: subtr. heterodyne math Reply with quote
Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2, one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

Claus

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PN2222A
Guest
Posted: Tue Feb 08, 2005 3:13 am    Post subject: Re: subtr. heterodyne math Reply with quote
"Claus Jensen" <cjensen@interdyne.com> wrote in message
news:4gjf01hlh44lsv57vqqekh9c7s81jhdvcv@4ax.com...
Quote:
The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?


0.4 * F2 = 8

?

Consulting services are available to program this into Excel, MathCad,
Matlab, or 8048 assembly.
Operators are standing by.
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Glenn Gundlach
Guest
Posted: Tue Feb 08, 2005 3:15 am    Post subject: Re: subtr. heterodyne math Reply with quote
Claus Jensen wrote:
Quote:
Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2,
one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio
of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to
0.6.

How do I solve this mathematically?

Claus

f2-f1=8
f1=0.6 f2
12 and 20 Hz
Hope you get a B
gg

(what, you want the actual arithmetic?)

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Andrew Holme
Guest
Posted: Tue Feb 08, 2005 3:15 am    Post subject: Re: subtr. heterodyne math Reply with quote
Claus Jensen wrote:
Quote:
Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2, one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

Claus

f1 / f2 = 0.6
f1 = 0.6 * f2

f1 = f2 - 8
f2 - 8 = 0.6 * f2

f2 - 0.6*f2 = 8
0.4 * f2 = 8

f2 = 20
f1 = 12
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John Woodgate
Guest
Posted: Tue Feb 08, 2005 3:18 am    Post subject: Re: subtr. heterodyne math Reply with quote
I read in sci.electronics.design that Claus Jensen
<cjensen@interdyne.com> wrote (in <4gjf01hlh44lsv57vqqekh9c7s81jhdvcv@4a
x.com>) about 'subtr. heterodyne math', on Tue, 8 Feb 2005:

Quote:
The frequency difference between F1 and F2 to be 8Hz. The ratio between
the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

F1 - F2 = 8................. (1)

F2 = 0.6 x F1............... (2)

Substitute from (2) in (1):

F1 -(0.6 x F1) = 8

0.4 x F1 = 8

F1 = 20 Hz

and thus F2 = 12 Hz

Maybe I didn't understand the question.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
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John Woodgate
Guest
Posted: Tue Feb 08, 2005 3:34 am    Post subject: Re: subtr. heterodyne math Reply with quote
I read in sci.electronics.design that PN2222A <bipolar@lithium.net>
wrote (in <DRQNd.1881$lz5.1072@newssvr24.news.prodigy.net>) about
'subtr. heterodyne math', on Mon, 7 Feb 2005:
Quote:

"Claus Jensen" <cjensen@interdyne.com> wrote in message
news:4gjf01hlh44lsv57vqqekh9c7s81jhdvcv@4ax.com...
The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?


0.4 * F2 = 8

No credit because no working is shown. If there had been, you would have
found that F1 is the higher frequency.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
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John Woodgate
Guest
Posted: Tue Feb 08, 2005 3:35 am    Post subject: Re: subtr. heterodyne math Reply with quote
I read in sci.electronics.design that Andrew Holme <andrew@nospam.com>
wrote (in <cu8m87$im7$1$8300dec7@news.demon.co.uk>) about 'subtr.
heterodyne math', on Mon, 7 Feb 2005:
Quote:
Claus Jensen wrote:
Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2, one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

Claus

f1 / f2 = 0.6 f1 = 0.6 * f2

No, the ratio of F1 to F1 is stated to be 1: 0.6, so F1 is larger than
F2.
Quote:

f1 = f2 - 8
f2 - 8 = 0.6 * f2

f2 - 0.6*f2 = 8 0.4 * f2 = 8

f2 = 20
f1 = 12

--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
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Joerg
Guest
Posted: Tue Feb 08, 2005 5:12 am    Post subject: Re: subtr. heterodyne math Reply with quote
Hello Claus,

I guess the math is easy and has been explained. As to the XR chip I am
not sure how to generate that without lots of alignment. I would cheat
and used a couple DDS chips. Computer does the math, send it to the
chips and out come the two desired sine waves.

Regards, Joerg

http://www.analogconsultants.com
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Tony Williams
Guest
Posted: Tue Feb 08, 2005 6:56 am    Post subject: Re: subtr. heterodyne math Reply with quote
In article <XVUNd.15939$mo2.1258516@news.xtra.co.nz>,
Terry Given <my_name@ieee.org> wrote:

Quote:
Let he who is without typos cast the first virtual stone :)

As an NZ'er you should know Harmer's Law, postulated
by Brian Harmer, of WYSIWYG fame.

All spelling/grammar corrections on Usenet have an eery
tendency to have spelling/grammatical errors.

--
Tony Williams.
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Terry Given
Guest
Posted: Tue Feb 08, 2005 7:50 am    Post subject: Re: subtr. heterodyne math Reply with quote
John Woodgate wrote:
Quote:
I read in sci.electronics.design that Andrew Holme <andrew@nospam.com
wrote (in <cu8m87$im7$1$8300dec7@news.demon.co.uk>) about 'subtr.
heterodyne math', on Mon, 7 Feb 2005:

Claus Jensen wrote:

Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2, one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

Claus

f1 / f2 = 0.6 f1 = 0.6 * f2


No, the ratio of F1 to F1 is stated to be 1: 0.6, so F1 is larger than
^^^^


Let he who is without typos cast the first virtual stone :)

Quote:
F2.

f1 = f2 - 8
f2 - 8 = 0.6 * f2

f2 - 0.6*f2 = 8 0.4 * f2 = 8

f2 = 20
f1 = 12



Cheers
Terry
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Rich Grise
Guest
Posted: Tue Feb 08, 2005 8:40 am    Post subject: Re: subtr. heterodyne math Reply with quote
On Tue, 08 Feb 2005 14:50:43 +1300, Terry Given wrote:

Quote:
John Woodgate wrote:
I read in sci.electronics.design that Andrew Holme <andrew@nospam.com
wrote (in <cu8m87$im7$1$8300dec7@news.demon.co.uk>) about 'subtr.
heterodyne math', on Mon, 7 Feb 2005:

Claus Jensen wrote:

Can someone help me get my head around this.

I need to generate a signal comprised of two sinewaves, F1 and F2, one
each from something like an XR2206. IOW their outputs are to be
summed.

The criteria is that the difference between the two generated
frequencies must be a specific single frequency, and that the ratio of
F1:F2 must be specifiied.

Here is an example of what is required.

The frequency difference between F1 and F2 to be 8Hz.
The ratio between the F1 and F2 frequencies to be 1:0.6, ie, 1 to 0.6.

How do I solve this mathematically?

Claus

f1 / f2 = 0.6 f1 = 0.6 * f2


No, the ratio of F1 to F1 is stated to be 1: 0.6, so F1 is larger than
^^^^

Let he who is without typos cast the first virtual stone :)


Let him. "who is without typos" is a subordinate clause, which modifies
"him", the object of the verb "let". ;-)

You wouldn't say, "let he cast the first stone", would you? ;-)

Cheers!
Rich
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Fred Bartoli
Guest
Posted: Tue Feb 08, 2005 3:00 pm    Post subject: Re: subtr. heterodyne math Reply with quote
"Joerg" <notthisjoergsch@removethispacbell.net> a écrit dans le message de
news:vBSNd.1997$lz5.1036@newssvr24.news.prodigy.net...
Quote:
Hello Claus,

I guess the math is easy and has been explained. As to the XR chip I am
not sure how to generate that without lots of alignment. I would cheat
and used a couple DDS chips. Computer does the math, send it to the
chips and out come the two desired sine waves.


Or you can use an XR to generate 16Hz, divide by 4 for 4Hz and mix :-)

Just one pot to trim!

--
Thanks,
Fred.
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Pig Bladder
Guest
Posted: Wed Feb 09, 2005 8:40 am    Post subject: Re: subtr. heterodyne math Reply with quote
On Tue, 08 Feb 2005 06:56:21 +0000, Tony Williams wrote:

Quote:
In article <XVUNd.15939$mo2.1258516@news.xtra.co.nz>,
Terry Given <my_name@ieee.org> wrote:

Let he who is without typos cast the first virtual stone :)

As an NZ'er you should know Harmer's Law, postulated
by Brian Harmer, of WYSIWYG fame.

All spelling/grammar corrections on Usenet have an eery
tendency to have spelling/grammatical errors.

Notwithstanding the eerie preponderance of citations op cit.

;-)
--
The Pig Bladder From Uranus, Still Waiting for
Some Hot Babe to Ask What My Favorite Planet Is.
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Tony Williams
Guest
Posted: Wed Feb 09, 2005 9:06 am    Post subject: Re: subtr. heterodyne math Reply with quote
In article <pan.2005.02.09.03.59.36.307866@neodruid.net>,
Pig Bladder <pigbladder@neodruid.net> wrote:

Quote:
Notwithstanding the eerie preponderance of citations op cit.
;-)

:)

--
Tony Williams.
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