IVIE IE-10A, Руководство владельца и оператора

Страница: 31 / 88

MEASURING DB-SPL WITH THE I E -
Operation of the f o r dB-SPL measurements i s very s t r a i g h t
The c o n t r o l panel o f t h e has been c o l o r coded t o make the o p e r a t o r
aware of the analyzer f u n c t i o n s t h a t a r e commonly used together. D i r e c t l y
below the s e n s i t i v i t y s w i t c h e s on t h e f r o n t panel t h e r e are
colored reference l e v e l s , i n b l u e and 140 dB-SPL i n red. Note
t h a t the INPUT s w i t c h i s a l s o c o l o r coded w i t h b l u e f o r an external
(EXT) signal source and r e d f o r i n t e r n a l (INT), i n d i c a t i n g t h a t the
bui t - i n microphone i s t h e s i g n a l i n p u t . With both s e n s i t i v i t y switches
s e t t o dB and the INPUT s w i t c h s e t t o INT, t h e dB g r a t i c u l e l i n e i s
140 dB-SPL as shown i n F i g . 23. The b u i l t - i n microphone i s c a l i b r a t e d
t o measure s i g n a l s i n dB-SPL i n t h r e e f i l t e r modes A, C, and OCT.
2 d B Scale
R e f .
F i g u r e 23
Determining what t h e dB-SPL r e f e r e n c e l e v e l i s on t h e analyzer simply
r e q u i r e s t h a t we add t h e two s w i t c h s e t t i n g s o f the s e n s i t i v i t y c o n t r o l
( i n c l u d i n g t h e i r minus and then add t h e i r value t o the 140
number.
R e f e r r i n g t o F i g . 24, n o t e t h a t one s e n s i t i v i t y s w i t c h i s s e t
t o -10 dB and t h e o t h e r i s s e t t o -60 dB f o r a t o t a l o f -70 dB. Adding
t h i s number t o 140 dB-SPL, 140 dB p l u s -70 dB s e t s t h e new reference t o
70 dB-SPL.
Note t h a t t h e DISPLAY s w i t c h i s s e t t o 3 dB per s t e p and
t h a t we must use t h e c o r r e s p o n d i n g 3 dB s c a l e on the d i s p l a y readout.
page 25