AM Demodulation

Build an AM demodulation system in GNU Radio as shown in the figure below:

The parameters adjusted for each module are as follows:

• File Source: File = [saved AM data file]
• Carrier: Frequency = 50e3
• Low Pass Filter:
  • FIR Type = Float->Float
  • Decimation = 1
  • Cutoff Freq = 13e3
  • Transition Width = 1e3
• GUI Range (gain):
  • ID: gain
  • Default: 1
  • Start: 0
  • Stop: 3
  • Step: 0.1
• Multiply Const: Constant = gain

The simulation results are shown in the figure below:

Exercise 4

1. Does the spectrum after demodulation match the theory? Is it the same as the original signal?
2. Try adjusting the LPF (Low-Pass Filter)'s Cutoff Freq and Transition Width to see the effects.