# Bandwidth and Carrier frequency

What is exactly the difference between the Bandwidth and the carrier frequency ? And if we have two channels with the same bandwidth but with different carrier frequency will we have different speeds ? For example :

• System A : Bandwidth = 1 Khz , Carrier frequency = 1 Ghz

• System B : Bandwidth = 1 Khz , Carrier frequency = 1 Mhz

If we used 16-QAM in both systems will baudrate be the same ?

• Do you understand the answer to this question: Why is channel capacity a factor of bandwidth instead of frequency? – The Photon Oct 30 '17 at 22:57
• Actually I couldn't understand this part " A single frequency signal would be a continuous tone. It's amplitude would never change. It would just continue on repetitively forever. As such, it would not convey any information." – Ali Safaya Oct 30 '17 at 23:10
• I mean why would it continue repetitively ? If so wouldn't we be able to transmit data over it changing phase like in PSK ? – Ali Safaya Oct 30 '17 at 23:13
• What is the fourier transform of $\sin(\omega t)$? If you change the phase then you have $\sin(\omega t + m(t))$. If you take the F.T. of this, you won't get the same as for the simple sine, you'll get something spread over a band of frequencies. Put another way: once you modulate the phase, you no longer have a single-frequency signal. – The Photon Oct 30 '17 at 23:19
• So the answer to the question is yes and speed stay the same ? – Ali Safaya Oct 30 '17 at 23:25