If you’ve ever wondered how dozens of cell phones can scream at the same 5G cell tower at exactly the same time without drowning each other out, the answer lies hidden in the mathematics of pseudo-random sequences. For decades, the undisputed king of multiple access was Code Division Multiple Access (CDMA), which relied heavily on binary mathematical constructs known as Gold Codes. But as we...
Digital data can be transmitted wirelessly over an analog channel in various ways. Let’s start with an explanation of digital data. Digital data in modern information systems is also known as binary data, which is represented by a string of “binary” digits (bits), each of which can only have one of two values, either 0 or 1. Sequencies of digital bits can be organized into...
The matched filter is one of the most useful tools available to the Digital Signal Processing (DSP) engineer. Matched filtering maximizes the Signal to Noise Ratio (SNR) of the filter output when a signal matching a known pattern is passed through it. This process is extremely useful for “finding” signal patterns, possibly hidden within a noisy signal (low SNR). One application is in...
This is a continuation of a previous post in which I examined the signal characteristics of a non-branded dog training collar. I purchased an additional training collar which has two functions: warning, and shock. Our 5 year old lab mix has a dangerous habit of chasing vehicles, and I wanted to curb his behavior as well as keep him safe if he bolted from our front door or gate. With the same...
I picked up a remote control training collar for our 7 year old Maltese to help train her in order to curb barking. In the spirit of keeping everything humane, we only use two of the three functions (alarm, vibrate, and shock), avoiding the shock function for obvious reasons. I became interested in the modulation used to encode the functions, so I used my Real Time Spectrum Analyzer to analyze...