Iridium ADC

Author(s) Information

Bill BlakelyFollow


College of Engineering


Electrical Engineering Department

Degree Name

BS in Electrical Engineering




Art MacCarley


Today's modern digital audio systems are pushing performance boundaries. Most high quality audio digital to analog converters are capable of 24 bit, 96 kHz conversion. Professional audio interfaces frequently use 24 or 32 bit 192 kHz sample rates. These systems are able to achieve dynamic ranges greater than 100 dB, and distortion on the magnitude of single parts per million. This project proposes a high resolution analog digital converter (ADC) to measure and characterize these types of devices.

The proposed system will be capable of 24 bit conversion and an extended frequency range compared to the typical 20 Hz to 20 kHz audio band. This allows for a theoretical dynamic range of over 140 dB, ensuring the systems noise performance is limited by other factors. The extended frequency response offers several benefits:

1. Measurement of distortion products that occur on fundamental frequencies above 10kHz. Even though these products are not necessarily audible, they should be observed if present.

2. Observation of out-of-band oscillations, interference, or other noise. Various issues in a device could result in unintentional self oscillation which will likely be at a greater frequency than conventional audio measurement equipment operating at a maximum of 192kHz can observe.

3. Measurement of non-audio signals. Many common signals operate in the tens or hundreds of kHz range. Switch mode power supplies operate in frequencies of 100kHz and up [1]. Industrial, scientific, and medical equipment may use ultrasonic equipment, and vibration or resonant analysis may produce signals that go well beyond 20 kHz [2].

The digitized data will be transferred over USB, and a custom program will display the data in time and frequency domain simultaneously. This interface also enables control over the sampling and data processing parameters.