When transmitting digital signals is
it necessary to transmit some harmonics in addition to
fundamental frequency?

• yes.
  see the Fourier series expansion of a square wave:
  4/(n*pi)*sin(n*2*pi*f*t) where n=0123....
  f:fundamental frequency=1/time period.
  so for good reconstruction of the square wave at the receiver side we need to send more frequencies rather than only fundamental frequency. because only one sine wave cannot make the square wave.
  
• 10 years agoHelpfull: Yes(8) No(0)
• Yes, A one frequency signal may not be sufficient, since the
  analog and digital signals may look different and the
  receiver may not recognize it correctly. To improve the
  shape of the signal for better communication, particularly
  for high data rates, we need to add some harmonics
• 9 years agoHelpfull: Yes(0) No(0)
• yes it is necessary to get a pure sine waveform
• 9 years agoHelpfull: Yes(0) No(0)