128-channel noise measurement system installed in Maryland

HGL has delivered and installed a 128-channel noise measurement system in Patuxent River, Maryland. The system consists of 16 Dragonfly modules. 12 of these units are standard units with IEPE signal conditioning for powering the microphones. The remaining four systems also have IEPE conditioning fitted, but also have GPS modules for precise synchronisation between units.

Each set of four modules (3 standard + 1 with GPS sync) is controlled via a Dragonfly CPU module. The unit with the GPS module acts as the master unit for the other 3, providing synchronisation via daisy-chained LVDS cables.

Dragonfly is HGL's new 24-bit distributed acquisition platform with TCP/IP output. More information is available on our Dragonfly pages here.

The system is used to provide real-time noise monitoring via whole-octave or third-octave filters. These filters are implemented in software using proper IIR filter algorithms, as opposed to less accurate approximations using FFTs. HGL's acoustics analysis tools provide efficient results that are compliant to IEC 1260, class 0.

In addition, the system computes overall A-weighted LEQ, compliant to IEC 61672-1.