Category Archives: Signal Processing

PSoC – Design and Implementation of a 12 Lead Portable ECG

Fully Assembled Compact, Portable 12 Lead ECG

During the academic year of 2016-2017 at McMaster University, in conjunction with Dr. DeBruin, Christina Riczu, Thomas Phan and Emilie Corcoran, we developed a compact, battery powered, 12-lead electro-cardiogram. The project won 1st place in the biomedical category at the ECE Capstone Poster Day.

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PSoC – AM Radio Transmitter

AM Transmitter with just a dev-kit!
AM Transmitter with just a dev-kit!

Previously, I wrote about the Cypress PSoC5LP microcontroller that I have been playing with. The CY8C5888LTI-LP097 on the CY8CKIT-059 dev-kit can be used to make a very crude radio transmitter. Today I will be explaining how to make some simple transmissions from a PSoC to a computer equipped with an RTL-SDR and SDR# acting as our radio receiver. We will be using configurable digital hardware to create the transmitter.

NOTE: If you decide to recreate my experiment, you should take a look at your country’s regulations for radio communicating devices. For example, the FCC in the United States allows hobbyists to create and operate up to 5 low power devices without a license as long as you follow some rules. Still, be responsible and don’t operate this for any longer then you need to know it works.

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Head Related Transfer Functions and Headphone Listening

Switchfoot-fft
Fast fourier transform output of the first 15 seconds of Switchfoot – Meant to Live. The left channel is displayed on top and the right channel on the bottom. This clearly displays extreme stereo separation.

Listening to stereo music through headphones has never sounded quite right to me. The extreme stereo separation can cause headaches for me when using headphones for more than an hour. Some people report experiencing “pressure” in their ears when using headphones This discomfort could simply be due to how unnatural headphone listening is; no sound from the left channel makes it to your right ear and vice versa. There are some tricks that can be used to get rid of these problems but before I show you how you can try out these tricks let’s get into the math and science behind head related transfer function (HRTF) and how they are used to simulate the way sound travels to our ears resulting in a better listening experience when using headphones with stereo content or even create what is known as virtual surround sound. Continue reading Head Related Transfer Functions and Headphone Listening