Showing posts from July, 2017


This week I got the opportunity to revisit MCity and see the Robocar, an autonomous vehicle capable of driving at up to 200 kph. It was very interesting to talk to the team working on it, shedding insight into how the Robocar was put together, what design challenges they faced, and of course, what sensors they use to gather information about the Robocar and its surroundings. For example, the car uses multiple LIDAR sensors strategically placed so that it can detect objects all around it. It also uses other sensors like RADAR and a 360°camera. I was also very interested in the engineering problems they faced. For example, I was surprised to learn that the car, with everything on it, weighed a metric ton, but without the motors and battery, weighed only 400 kg. It was also interesting that they opted to use 4 individual motors - 1 for each wheel. As it stands, the more they are able to show that the car has good decision making and can drive autonomously at speeds at or exceeding 200 kp…

Quadrature Amplitude Modulation

In an effort to better understand other methods of signal modulation, I decided to read up on Quadrature Amplitude Modulation. QAM is a method of transmitting a signal in a more efficient way. While Amplitude Modulation varies the amplitude of a signal to encode data, Frequency Modulation changes the frequency of the signal, and Phase Modulation modifies the phase, Quadrature Amplitude Modulation uses a mix of two of the three. It uses two carrier waves, a sine and cosine (in other words, one wave phase shifted by 90 degrees), and modulates using both amplitude and phase variations. A scheme like this is more efficient than simply Amplitude Modulating a signal. By having two phase shifted carrier waves, there is another channel to transmit information. It can also allow multiple bits to be encoded per symbol, which allows for schemes like 16QAM. It's not without drawbacks, though - things can get pretty confused if there is too much noise. Still, a scheme like this is pretty cool …