Using An External Signal - BRUEL & KJAER 4297 User Manual

22 Sound Intensity Calibrator Type 4297 – User Manual
4.3

Using an External Signal

Fig.4.1
Rear view of
Type 4297. An external
noise source can be
applied to the LEMO
socket on the right
It is possible to apply an external signal to Type 4297.
✐
Use only Brüel & Kjær cable AO-0440 (BNC to LEMO cable).
Please note:
1) Connect the external generator to the LEMO socket (Fig.4.1).
2) It is necessary that Type 4297 is switched on. Press Start and select broadband pink noise. The
LED indicator should be illuminated.
3) Ensure that the rms voltage applied to Type 4297 does not exceed 70 mV rms (94 dB
approximates to 65 mV with the spacer in place, but the exact figure is dependent on the
frequency applied).
4) In the frequency range 20 Hz to 10 kHz, both sine wave and broadband pink noise signals may
be used. The use of a sine wave signal gives more stable results and allows for corrections of
phase mismatching in the sound intensity probe.