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Topic: Generating Square Wave with with modulated carrier frequency (Read 14226 times) previous topic - next topic

polymorph

That isn't what it looks like in his Youtube video.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

CrossRoads

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

polymorph

We need more information. Turn down the brightness on your scope and zoom in.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

nehe_bhimaji

Dear Sir
I have attached original board block diagram.They have used ATMEGA8 controller for it.Basically it is used for generating mechanical vibration in a PAN.
Another thing I have take a  changing part of the waveform and zoom it by Increasing Timebase .I surprise by seeing the carrier pulses in it  but due to limitation of my oscilloscope I can not zoom it further.


nehe_bhimaji

Waveforms that i have seen after zooming is attached here

CrossRoads

So you're doing analog mixing of two digital timer signals.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

nehe_bhimaji

Dear Sir
How this can achive using arduno uno
I think that is the mixing of two timer waveforms

CrossRoads

Start by reading about the timers and setting them up here
http://www.gammon.com.au/forum/?id=11504

Hard to say from your scope shot how often the 2nd timer is delay past the 1st to make the jittery looking output.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

nehe_bhimaji

Dear Sir
According to there board scheme I think they have used timer 1 to generating the waveform guaging it due to used of pin PB2 and PB3 .But I am unable to understand how they will toggle the same pin of timer to generate the jeters.Any idea to do it
Thanks

polymorph

Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

nehe_bhimaji

Dear Sir

OK   as you say you require waveform ,please find here attached waveform that I think will work for me.I have tried it with Timer 1 But without success.
Please give some idea or sample sketch for the same.
Thanks

polymorph

This should have been the first thing you gave us.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

nehe_bhimaji

Dear sir
This thing we have decide yesterday.But do not know how one can achive the same.
Thanks

polymorph

You could gate an external oscillator using two PWM outputs. Both at 50% when A0 is at 0%. Then as A0 increases, one reduces PWM, the other increases PWM. An external XOR logic is used to gate an external 5MHz clock.

But - what kind of resolution do you need and how accurate must that 18kHz be? You can set a higher PWM frequency from the Arduino, but it isn't infinitely variable, and the resolution (bit depth) is reduced at higher frequencies.

I come from a hardware background. So I picture doing this with a crystal oscillator divided down to 5MHz and 18kHz, using a ramp to generate the PWM signals, XOR to gate the 5MHz signal, and use the Arduino to control the ramp/PWM generator.

I'm sure someone here can help with doing nearly all (or all) in software. Perhaps with something faster like a Due or Teensy 3.1.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

nehe_bhimaji

Thanks for reply
I wish to do all these things in software preferably arduno uno
Thanks

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