11 Replies Latest reply on May 24, 2018 12:27 PM by tn49179_3003661

    Filtering digital signal

    tn49179_3003661

      Hi,

      I'm using CY8CKIT-048 PSoC Analog Coprocessor Pioneer Kit and I am trying to make an FSK demodulator. I tried implementing the demodulator by following and modifying AN2336 made for PSoC1, but I run into problems when I want to filter correlator output signal.

      I attached my project so you can check it out.

      I am generating a sine wave test signal using PWM, DMA and VDAC. Sine wave table and generated sine wave frequencies are set up so that I should get a capital letter 'U' at demodulator output. That signal is connected to a comparator. Comparator output signal is routed into SmartI/O component in which I implemented a shift register. XORing original signal and signal delayed using a shift register should give me an output of high or low duty cycle, based on the frequency of the sine wave, and that signal should be connected to UART and UART should sent that data to my pc where I can see the output data of demodulator in a terminal. But that correlator output signal has some pulses i would like to iron out because I don't get good enough results. I attached a screenshot from the oscilloscope so you can see what I mean. Yellow channel is the signal I need to iron out.

      How do I filter these pulses out? This PSoC doesn't have any digital filtering or glitch filter components as far as I know.

       

      Thanks,

      Tomislav