What is Dynamic Range?
The dynamic range of a device is the ratio of the largest and smallest signals that can be measured by circuit, normally expressed in dB.
Dynamic Range in dB = 20 * log10( Vmax / Vmin )
In most cases, the full scale input of a device is the largest signal that can be measured and the idle channel input noise determines the smallest signal that can be measured. National Instruments DSA devices specify Dynamic Range, Idle Channel Noise, and Spectral Noise Density, all of which can be used to calculate dynamic range. The easiest way to measure your device’s dynamic range is to take an idle channel noise measurement and convert that measurement to dB full scale, as described in KnowledgeBase 4X31Q728: How Do I Measure the Dynamic Range of My Data Acquisition Device?
Dynamic range is a very important quantity to consider when choosing a DSA device. Oftentimes, DSA applications require the use of microphones and accelerometers- sensors that have very large dynamic ranges. Choosing an appropriate measurement device will allow you to take advantage of these sensors and the fullness of their range.
Note: When comparing dynamic range specifications between devices, it is very important to make sure that the measurement bandwidth, sample rate, input range and input tone are identical. If any of these vary, the dynamic range comparison will be misleading.