AM Signal Generator/Demodulator (Under Construction)

This workspace demonstrates how to generate AM signals with the Analog Discovery 2 and how to demodulate the signal to see the original waveform. The carrier frequency is 150kHz, the AM signal is 1kHz.

The signal detected by the oscilloscope is processed through two functions that mimic the circuit elements used in an AM demodulator. “H-W Rectifier” mathematically mimics a half-wave rectifier and passes the positive half of the signal through while nullifying the negative. “Low Pass” is a software-based 2nd order low pass Chebyshev filter with a cutoff frequency of 2kHz. This isolates the signal that is being transmitted through the amplitude modulations. An actual demodulator would have subsequent steps, but this workspace demonstrates a signal conditioning technique for demodulating AM signals.

• WaveForms
• A Discovery Device:
  • Analog Discovery 2
  • An Analog Discovery (Legacy) can also be used
• Pmod TMP2
• 2 pull-up resistors 1kΩ-100kΩ
• AM Signal Generator/Demodulator ZIP Archive

Download and extract the WaveForms workspace from the AM Signal Generator/Demodulator ZIP (also linked in the inventory section, above).

The workspace is ready to use and only requires that the Oscilloscope Channel 1 wires (solid orange and striped orange) be connected to the Function Generator Channel 1 (yellow) and ground (black), respectively.

To capture a sample of the AM signal, press the “Single” button in the Scope 1 screen on top, and then press the “Run All” button twice in the Wavegen 1 screen on bottom. Each stage of the demodulation will be graphed, and can be toggled on or off. The stages of the demodulation are in order from top to bottom.

For more guides and example projects for your Test and Measurement device, please visit its Resource Center, which can be found through this wiki's Test and Measurement page.

For technical support, please visit the Digilent Forums.