EEL4514C Lab 5 - Lab Assignment for Communications under Dr. Wong PDF

Preview

Summary

Lab Assignment for Communications under Dr. Wong...

Description

Yu Liu EEL4514C Lab 5 Lab Report Theoretical: In this lab we learn about quadrature amplitude modulation. We will be creating a rectifier receiver to receive a signal that will be transmitted in lab. Using our knowledge of carrier frequencies and filters, we will be trying to create the best receiver with little noise so we can hear the received signal to the best that we can.

Implementation Description: In lab I used the GNU radio blocks to create the block diagrams described in the lab document. We implemented a rectifier receiver with a sampling rate of 264.4 kHZ. We used a osmocom Source block which mixes the received signal (woman’s voice) with a carrier frequency which is then decimated through a rational resampler and sent through a complex to Magnitude block. The DC components were also blocked to prevent additional noise into the receiver and then everything was filtered through a low pass filter to clear up the transmitted signal even more so the received signal could be the most free of noise as possible.

Figure 1: Receiver block

Yu Liu

Figure 2: PSD of voice

Results: Using the envelope detection block diagram that was designed on GNU, the signal was able to be received. It was a woman’s voice reading out random nonsense sentences such as: “the lazy cow lay in the cool grass.” There were other phrases but there was a lot of noise that it was hard to make out what the words were. Some of the other phrases included words like “king” and “fence.”...