subtr. heterodyne math

C

Claus Jensen

Guest
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
 
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
Click to expand...
f2-f1=8
f1=0.6 f2
12 and 20 Hz
Hope you get a B
gg

(what, you want the actual arithmetic?)
 
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
Click to expand...
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
 
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:

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?
Click to expand...
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
 
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
 
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 :)
Click to expand...
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.
 
"Joerg" <notthisjoergsch@removethispacbell.net> a écrit dans le message de
news:vBSNd.1997$lz5.1036@newssvr24.news.prodigy.net...
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.
Click to expand...
Or you can use an XR to generate 16Hz, divide by 4 for 4Hz and mix :)

Just one pot to trim!

--
Thanks,
Fred.
 
On Tue, 08 Feb 2005 06:56:21 +0000, Tony Williams wrote:

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.
Click to expand...
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.
 
In article <pan.2005.02.09.03.59.36.307866@neodruid.net>,
Pig Bladder <pigbladder@neodruid.net> wrote:

Notwithstanding the eerie preponderance of citations op cit.
;-)
Click to expand...
:)

--
Tony Williams.
 
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