November 2017 – CloudACM

Decoding DTMF with MultiMon-NG

November 27, 2017 Patrick Gilfeather

Dual Tone Multi Frequency signaling, commonly referred to as DTMF, is mainly used for phone dialing systems. But this isn’t the only use for DTMF signaling. Another common use is security access systems. In this post, I’ll be covering how to decode DTMF using MultiMon-NG. SoX will be used to record the DTMF signals generated on cell phones and keyless entry systems. I’ll be using a high gain directional microphone with a secondary microphone to cancel out background noise. SoX…

Sonic data analysis with SoX

November 20, 2017 Patrick Gilfeather

In this post I’ll be using SoX to export audio to data values that can be processed outside the audio realm. The example I’ll use here is a breif recording that will be plotted with GNUPlot. SoX and other programs provide spectrograms, which are frequency domain images of audio files. I’ll be using GNUPlot to create an image of an audio file in the time domain. First, I’ll use this command to convert the audio wav file into a text…

Noise Cancelled Microphone with SoX

November 13, 2017 Patrick Gilfeather

In this post I’ll be using two USB microphones to record audio, one for the intended sounds I wanted to record, the other to capture background noise that I want to filter out. I’m using two cheap USB embedded microphones that I bought for less than $10 each, http://a.co/eIsnp3Z. The machine I’m recording on is a Raspberry Pi 3 running Ubnutu Mate. Since the Raspberry Pi doesn’t have an audio in device built in, I selected the USB microphones. These…

CloudACM

Autonomous Computational Machines – From Cloud To Chip

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Month: November 2017