In this post I’ll cover how to remove noise in an audio file using SoX. I’ll be using a Raspberry Pi which does not have an audio input by default. To get audio, I used an simple USB audio microphone to capture audio. The OS I’m running on my Pi is Ubuntu Mate and there was no need for anything to get the microphone to run. Once it was plugged in, I ran this command to view the properties of…
In this post I’ll show how SoX can generate DTMF, (Dual-tone multi-frequency signaling) which is commonly used in phone and security systems. These dual tone signals are the foundation from which digital communications are based. The technology around DTMF is not complex. Lets cover the history of DTMF. DTMF was developed by Bell Labs and put in production in the early 1960’s. It was mostly used to replace pulse dialing systems that had limits on how far a phone could…
In my last post I suggested creating noise and using a band of it to fill in a band gap. SoX provides a way to generate noise. There are different types of noise that SoX will generate. Lets take a moment to look at these types and what applications noise generation is used for. There are 3 main types of noise that SoX will generate, they are white, pink, and brown. White noise is a random signal that has equal…