Decoding On-Off Keying modulation

Projects Programming
1

Hi, I am having issues with coding a sketch that will decode the signal that is seen in the picture below.
What I am trying to do is basically sample the voltage at a specific interval using analogRead() and after that using an if.... else statement with a voltage threshold value to determine which values are going to be a '1' or '0' printed on the serial monitor.
I am having problems trying to sample a specific interval as my current code below is continuously sampling the voltage through analogRead().
Delays do not seem to be working probably because it is a blocking function.
Hopefully, the picture below can help to visualize what I am attempting.

Any suggestions on how to achieve this specific sampling interval would be appreciated.
I am sure there is a more intelligent way of approaching this issue.

Inked560uS pulse width, 4X560uS time space between pulses_Marked
Inked560uS pulse width, 4X560uS time space between pulses_Marked1920×1440 248 KB

Code/General Idea:

int analogPin = 3;     
                       

int val = 0;           



void setup()

{

  Serial.begin(9600);         

}



void loop()

{
  val = analogRead(analogPin);    
  Serial.println(val);
 
  if(val>100)
  {
    Serial.print(1);
  }
  else
  {
    Serial.print(0);
  }
  
}
2

Hello
try

if(val>100)
  {
    Serial.print("1");
  }
  else
  {
    Serial.print("0");
  }
3

Trying hard to see the improvement there

If you're not doing anything else, AND accounting for the time taken by analogRead, that shouldn't necessarily be a problem.

4

Hi, and thanks for the reply.
The time for analogRead to process (100 microseconds) was taken into account and there are no other processes running in the background.
I suppose there must be an issue with where the delay is positioned.
Previously it was positioned right after the if...else statement.
Could this be the issue ?

int analogPin = 3;     
                       

int val = 0;           



void setup()

{

  Serial.begin(9600);         

}



void loop()

{
  val = analogRead(analogPin);    
  Serial.println(val);
 
  if(val>100)
  {
    Serial.print(1);
  }
  else
  {
    Serial.print(0);
  }
  delay(); //Positioned delay here previously
}
5

How long?

6

It was set at 1.22ms.
Which is about two pulse widths of 560us each and adding the 100us analogRead processing time.

7

But that would be delayMicroseconds (1220).
Also you may need to take into account the slow baud rate.

8

Yeah, I think using delay(1.12) may have been affecting it along with the slow baud rate which I have overlooked entirely.
Anyway, thanks for the advice and I'll try and incorporate these inputs when I'm back in the lab.

9

You mean "delay(1)" :wink:

10

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