Bruel & Kjaer’s 3535 all-weather case is a short- to medium-term noise monitoring system that protects unmanned equipment. The compact, lightweight enclosure includes a sound-level meter and outdoor microphone. The 2250 noise analyzer and 4952 outdoor microphone are type-approved to provide Class 1 measurements to IEC 61672-1:2002. Two slim-line, lithium-ion battery packs provide the power to operate all equipment inside the case. The battery provides 12 days of daytime monitoring with a case weighing less than 7 kg and can be recharged in the case. High-speed, internet-based communication is provided by a 3G or GPRS modem, allowing remote data retrieval and monitoring of real-time noise levels.