Hello,

I made a circuit that's output (blue colour (it's asynchronous)) and transmitted this signal by On-Off Keying (OOK) modulation type:

But I'm trying to find some reveiver or demodulator circuit for more than day, but can't find...

I have tried to use envelope detector circuit, that looks like this:

It's ok for ASK, but it won't work for OOK. I have tried to simulate a lot of possibilities, but nothing worked well.

Maybe some one have tried to do this and can send me some link or approach to solve this problem? Better if there were circuit (schematics) so I could simulate it in PSpice.

P.S.
Thanks for any help

 

It should work. A common mistake is to make the capacitor too large. What are you getting?

 

Thanks for your answer.

Here is my simulation system:

And here is what I get in bigger picture:

I Use asynchronous system and there is very imoprtant to know the time when input signal changed his edge. But like you can see in picture after transmison and decoding using enveloped decoder, decoded signal (time events when input signal switched) are incorrect. I what this edge more accurate. Like you can see, for now the error ir about 0.1ms from real signal.

Any suggestions? circuits? approach?

Thanks

 

You definately need a Schmitt Trigger. It will clean it up.

 

You definately need a Schmitt Trigger. It will clean it up.

Thanks for your help

I tried to use Schmitt trigger with hysteresis with unipolar voltage source, but can't get appropriate levels, I want, that ir switch when it reach 0,09V (0.9V in picture) and 0.1V (in picture 1,7V) levels in my circuit:

Maybe you can suggest exact circuit for that? Without using other voltage source, becouse I tried with comparator where I put 0,1V voltage source and then everything works fine, but this approch isn't suitable for my aim.

Thanks

 

you need to try a device called : ASK RECEIVER MODULE

- look up a taiwan manufacturer called WENSHING.COM.TW

_ search for this company on google

_ click on link for ASK RECEIVER

- it will work for OOK type modulation as well _ TRUST ME

- try device with part no. RWS - 374 - 4

- experiment with it on prototype board on your workbench ...

- best of luck ..

 

you need to try a device called : ASK RECEIVER MODULE.... .... ....

Do you mean this:
http://www.wenshing.com.tw/Data_Sheet/RWS-374-1_303.875MHz_ASK_RF_Receiver_Module_Data_Sheet.pdf

From datasheet I don't understand, can ir receiver asynchronous data? It look like not, becouse the output ir 1 0 0 1, but I need time events.
And how much channels it can receive?

 

You definately need a Schmitt Trigger. It will clean it up.

Thanks for your help

I tried to use Schmitt trigger with hysteresis with unipolar voltage source, but can't get appropriate levels, I want, that ir switch when it reach 0,09V (0.9V in picture) and 0.1V (in picture 1,7V) levels in my circuit:

Maybe you can suggest exact circuit for that? Without using other voltage source, becouse I tried with comparator where I put 0,1V voltage source and then everything works fine, but this approch isn't suitable for my aim.

Thanks

 

Designing a Schmitt Trigger isn't hard. Think in terms of voltage dividers when it is on and when it is off. You want to have the switching voltages you've set to match the divider voltages. Is this something you've never done?

http://www.allaboutcircuits.com/vol_3/chpt_8/12.html