Sine and?

[wizard]

Hi,

Today when someone asked me something about sine waves, we went for a way to see what job we have to do to get a signal like the bellow picture(the second)?
I mean suppose you have a pure sine wave(the first pic) and you want to get a wave form like the second by putting another small signal on pushes of the sine wave(like the second raw picture which I have drawn using Microsoft paint)

How to do that? what we can call the second signal? Is it related to modulation? Is it kind of modulation or if it has any special name in Electronics? Is it use in Electronics anyway?

Thanks

 

[wizard]

As far as I know there are 3 kinds of modulation. AM, FM and phase modulatrion. So it would not be a modulated signal, So what it is?
Please don't say that it is a distorted sine wave because you can suppose it would be our desire signal finally not an odd signal.

 

[Nigel Goodwin]

It's basically AM, but using a low frequency carrier (with higher frequency modulation), and a very low modulation level.

 

[on1aag]

Hi Wizard,

You could simply add a signal or even noise to the sine wave.
(With a much smaller amplitude than the original sine wave.)

A closer look a your second drawing revealed that the
superimposed signal is going back in time, that's going to
be a bit more difficult to achieve . . .

on1aag.

 

[audioguru]

The modulation on the sine-wave is random. Noise is random so the second sine-wave is AM modulated a little with noise.

 

[Willbe]

Hi,

Today when someone asked me something about sine waves, we went for a way to see what job we have to do to get a signal like the bellow picture(the second)?
I mean suppose you have a pure sine wave(the first pic) and you want to get a wave form like the second by putting another small signal on pushes of the sine wave(like the second raw picture which I have drawn using Microsoft paint)

How to do that? what we can call the second signal? Is it related to modulation? Is it kind of modulation or if it has any special name in Electronics? Is it use in Electronics anyway?

Thanks

If you look closely at your modulation in the second image you'll find it actually goes backwards in time at some places.
Hurry and patent this one!

 

[wizard]

It's basically AM, but using a low frequency carrier (with higher frequency modulation), and a very low modulation level.

Oh, so please we can have an example:
we use an AM modulator for 1MHz signal as carrier and 3MHz signal as a modulating signal right? So what will happen?
Do you know if a such wave(signal) has any usage in electronics?

 

[wizard]

Hi Wizard,

You could simply add a signal or even noise to the sine wave.
(With a much smaller amplitude than the original sine wave.)
on1aag.

How to do so? I mean how to put a CONTROLLABLE signal On larger one (like my figure)?

 

[wizard]

The modulation on the sine-wave is random. Noise is random so the second sine-wave is AM modulated a little with noise.

But it does not seem to be a normal AM, like what is used in radio comunication!

 

[wizard]

If you look closely at your modulation in the second image you'll find it actually goes backwards in time at some places.
Hurry and patent this one!

I must patent my miraculous hand lol.

It was drew using Microsoft Pain software(I drew it by the pencil of The Paint at less than 4 seconds)

 

[on1aag]

Hi Wizard,

Is this what you want to achieve ?
It's only an addition of two signals with different frequency
and amplitude, 100 Hz / 1 volt and 1234 Hz / 100 mV.

on1aag.

 

[crutschow]

Oh, so please we can have an example:
we use an AM modulator for 1MHz signal as carrier and 3MHz signal as a modulating signal right? So what will happen?
Do you know if a such wave(signal) has any usage in electronics?

Such a signal is interesting but has no practical usage that I'm aware of.

In normal AM modulation the modulation frequency is much lower than the carrier frequency, the opposite of what you are doing.

 

[wizard]

Hi Wizard,

Is this what you want to achieve ?
It's only an addition of two signals with different frequency
and amplitude, 100 Hz / 1 volt and 1234 Hz / 100 mV.

on1aag.

Thanks,

Yea that's what I and my friend are thinking of.
But please be noticed that we have two INPUTs which one generates a pure sine wave and the other generates those small signals.
How are we able to generate it? An AM modulator will do the task?
My friend has an idea according to sound and tweeters.
I will say his idea tomorrow one I could get more time.

 

[wizard]

By the way, How did you generate the wave on the pic?

 

[wizard]

So an AM modulator is able to do so.
Is there any AM integrated chip or I have to go for transistors?

 

[MrAl]

Hello there,

There is an application or two that i can think of that uses this type of
modulation.

One is a remote transmitter/receiver system that works over ordinary
household power lines (like 120vac 60 Hz) rather than totally wireless.
The carrier signal transmitted has a frequency of 200kHz.

The second is the same really, but digital information is transmitted
for the purpose of controlling lights and other appliances remotely,
by simply plugging in the transmitter to a home ac outlet.

They both work on the same principle...
The transmitter injects a signal onto the power line and the receiver
uses a filter to monitor the 200kHz signal and reject the 60Hz line frequency.
The 200kHz signal would appear to ride on the 60Hz line sine wave.

wizard: check out National Semiconductors site to see if they still have
app note AN146 available online. This is a full writeup of the circuit
i mentioned first.

 

[on1aag]

Hi Wizard,

By the way, How did you generate
the wave on the pic?

I simply connected two voltage sources with different
frequencies and amplitudes in series. Sorry no magic.
You don't need a modulator to achieve this result.
It's so simple I'm having difficulties to explain it.
I think you need a knock on your head.

on1aag.

 

[MrAl]

Hi on1,

Sorry that the transmitter/receiver i mentioned previously doesnt work
as simple as that It has to work into the 60Hz power line so there
is a bit more to it.

 

[crutschow]

So an AM modulator is able to do so.
Is there any AM integrated chip or I have to go for transistors?

You can use an analog multiplier IC to perform modulation. Analog Devices sells many different versions Analog Devices: Analog Multipliers/Dividers :: Other. If you want to just add the two signals together you can use a op amp in a summing configuration.

Modulation multiplies the two signals together which gives you sum and difference frequencies.

Summing simply adds the two signals together. You end of with just the two frequencies, no sum or difference frequencies.

Which you do depends upon what you are trying to achieve.

 

[wizard]

Hello there,

There is an application or two that i can think of that uses this type of
modulation.

One is a remote transmitter/receiver system that works over ordinary
household power lines (like 120vac 60 Hz) rather than totally wireless.
The carrier signal transmitted has a frequency of 200kHz.

The second is the same really, but digital information is transmitted
for the purpose of controlling lights and other appliances remotely,
by simply plugging in the transmitter to a home ac outlet.

They both work on the same principle...
The transmitter injects a signal onto the power line and the receiver
uses a filter to monitor the 200kHz signal and reject the 60Hz line frequency.
The 200kHz signal would appear to ride on the 60Hz line sine wave.

wizard: check out National Semiconductors site to see if they still have
app note AN146 available online. This is a full writeup of the circuit
i mentioned first.

Good idea but let me say what my friend desires to do.
He wants to play a sine signal by a tweeter at say 12kHZ(audible) and carry a HIGH frequency signal on it(say 25kHz), If you know what I mean.
He wants to have a simple audible sound signal and an ultrasound signal at the output of the tweeter simultaneity. So you will hear the 12kHz signal by your own ears and the ultrasound signal by a RECEIVER (a circuit which detects ultrasound I.e 25kHz here and divides it by 2).
We thought of a signal like what I shown you at the picture(the first post).But i am pretty sure that it does not do his job and cause the audible signal to be distorted unless we have a very small amplitude ultrasound signal
Any solution or trick (modulation or none modulation) which can cause the job to be done is welcomed.