Go Down

Topic: (solved) Wave voltage summing . (Read 1 time) previous topic - next topic

amine2

Dec 18, 2015, 12:51 pm Last Edit: Dec 19, 2015, 07:10 pm by amine2
THIS IS NOT FOR ANALOG VIDEO .

   - so i have a voltage running between 0v and 1v and that represents the first value i need to send X.
 then on top of that i need to overlay a sine wave , of a controllable faze Y and controllable amplitude Z.
the phase element is not crucial .

 so what i need is a chip that generates and alternative sine wave of controllable amplitude .
 and a circuit that would sum the voltage output of the sine wave generator with the already set value X .
 ( i think that could be done with an amplifier but i dont know how that's exactly done)
 

        thank you very much
it's all about the melons .

yendis

I take it you mean controllable frequency not phase (since phase implies a reference to some other timed event)?   If so what range of frequencies do you want?

Also you want the sine wave to have a DC component variable from 0V to 1V?  That can easily be added to most circuits.

There are many ways to generate sine waves, be useful to know what freq and whether distortion/harmonics are important.

Chris

amine2

Yendis thank you very much for your attention .
first the phase is given in the beginning in a short burst so that element should not matter , the frequency is also fixed to a specific N0 value . what changes is only the AMPLITUDE so if Um is the amplitude given by the microcontroller the sine wave should alternate between -Um and Um .
it should be a sine wave of a decent quality .
it's all about the melons .

MarkT

You need to start explaining what you want with numbers.  "decent quality" is almost meaningless,
"< 0.1% harmonic distortion" is completely clear.

Rather than tell us what its "not for", how about telling what you want to do?  We've no idea at all
what frequencies are involved, whether you are talking purely analog, or whether D->A converter is
intended, or what...  Perhaps what you want to achieve can be done differently from what you believe?

http://xyproblem.info/
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

amine2

hey MarkT , i am attempting to send a signal that is very similar to colored TV analog signal but it's not for a TV , the signal is a voltage value that matches the preps i lists up there in my original , forget about the sine wave quality , all i need is a sine wave you can recognize as a sine wave by looking at on an oscilloscope , that's all , the quality is therefore not so important . as long as it's a sine wave it will work . the signal is purely analog .
it's all about the melons .

MarkT

[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

amine2

ok . all i need is a circuit to sum two voltages (with sign consideration) .

            Vout = Vin1 + Vin2
 
EXAMPLE (with numbers) : if Vin1 = 0.5v and Vin2 = -0.2v we get Vout=0.3 .


then i need a chip that would generate a sine wave with a fixed frequency and phase , but with a variable amplitude , the microcontroller must be able to control the amplitude via any mean of communication possible (preferably a fast one)

how compilcated is that
it's all about the melons .

Grumpy_Mike

Numbers, need numbers.
No amine2 that is not what MarkT is asking. Fuzzy statements like
Quote
preferably a fast one)
Do not at all cut it in engineering, we need numbers that describe these concepts of fast. One Man's fast is another Man's slow.

Quote
i am attempting to send a signal that is very similar to colored TV analog signal but it's not for a TV ,
So would a TV pattern generator chip do?

MarkT

If you don't say what bandwidth is needed there's no point answering.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

amine2

ok , l'ets say i want to generate a color PAL signal , that's close enough .
hey Mike long time no see.
it's all about the melons .

Grumpy_Mike

OK cheapest option is a Raspberry Pi, that has a PAL video output which you can change.

MarkT

#11
Dec 18, 2015, 10:36 pm Last Edit: Dec 18, 2015, 10:37 pm by MarkT
So several MHz - rules out opamps, you're going to need a software defined radio chip or
something like that.   The final summing can be done by using transformer coupling - one side
of secondary goes to the (decoupled) DC offset voltage.

Use a tuned transformer and you've got "decent sine wave"!
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

yendis

I am still not clear on your requirement.You started asking for one dc voltage to be added to the sine wave, but seem to have added an extra one? 

quote: ok . all i need is a circuit to sum two voltages (with sign consideration) .

            Vout = Vin1 + Vin2
 
EXAMPLE (with numbers) : if Vin1 = 0.5v and Vin2 = -0.2v we get Vout=0.3 .


I guess your sine wave is not audio, but more like video frequency?   And you want to generate bursts of sine wave starting at a known phase? 

Maybe you could draw the waveform?
Chris

amine2

here are the diagrams , the first one is the DC voltage , the second one is the wave and the third is the output

it's all about the melons .

MarkT

[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

Go Up