What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?

  1. Removal of the CW signal as well as the interfering carrier
  2. Any nearby signal passing through the DSP system will overwhelm the desired signal
  3. Received CW signals will appear to be modulated at the DSP clock frequency
  4. Ringing in the DSP filter will completely remove the spaces between the CW characters