The outdoor microphone are designed for permanent installation in the field, for example airport noise monitoring or industrial plant noise monitoring. It includes anti-bird spikes, a windscreen and a rain cover, all of which are integral parts of the acoustic omnidirectional characteristics offered by the system.
The rain cover contains an electrostatic actuator enabling a precise in-situ calibration at 1000Hz from the internal sine wave generator. Optionally, the complete frequency response may be calibrated using an external generator. A special adaptor allows acoustic calibration.
The microphone diapragm and housing are made of stainless steel to withstand pollution and corrosion. The microphone cartridge is a ½" type with 200V polarisation voltage. The unit comes with a built-in A-curve spectral weighting network in addition to Flat response (no spectral weighting at all) and a 0 or ±20dB amplifier - all set by internal jumpers. An internal heating system is provided to avoid condensation. The output amplifier is a low noise type designed to drive long cables. The microphone is delivered in two versions: Nor1210A, for airport noise monitoring (0° i.e. vertical incidence) and Nor1210C for community or traffic noise monitoring (90° i.e. horizontal incidence)
Both versions are PTB (Physikalisch Technische Bundesanstalt, Germany) approved as part of an IEC 60651 type 1 system. Both versions also comply with ANSI S1.4.