Decoder Circuit Question

[greenthumb]

I recently built a new 2-level decoder (using the circuit on http://www.radioreference.com/wiki/images/4/4e/Circut.gif ) and when I run slicer on it, the interrupts seem to take place when the received signal strength is low, rather than high. Any ideas on where the problem might be? I tried running it inverted and using other pins, but I haven't come up with any luck.

Thanks!

 

[Al42]

Do you mean that the interrupts occur when the received signal goes high, or are you referring to a signal that varies in strength? The signal strength shouldn't affect whether the circuit works (causes interrupts), until the signal gets too weak for detection.

 

[pro92b]

There is probably too much hysteresis in the referenced circuit for it to switch properly. Try shorting R2 temporarily to see if it starts working. You can use Slicer.exe to test for basic operation. Also read the file at http://home.hvc.rr.com/bpetrow/slicer_design.zip to learn about how slicers should be designed.

 

[DaveH]

I find that for strong signals, decoding is better with R1 disconnected, but for weaker signals R1 should be in place.

Dave