Model 820 Technical Reference Manual
Understanding the Model 820 Keypad
2-7
D
T.A.:
Time Weighted Average SPL(TWA) and
the German Takt Maximal Levels(TAKT),
are available through the T.A. key. The first
display (-a) shows the Overall TWA and Run-
Time.
LDN:
The LDN is a TWA with a 10dB pen-
alty added to the levels measured from 10 pm
to 7 am. It is used to assess, correlate or pre-
dict annoyance to noise in residential area;
noise at night is generally less tolerated than
noise in daytime hours. CNEL is also shown.
LDN-b: Shows the average levels of the
exceedances and the average levels (Bk Gnd),
of energy not contained in exceedances.
E
DOSE:
The Dose and Projected Dose sound
exposure percentages are displayed in these
screens. Parameters #48-51 control the Dose
measurement.
LDL:
Logged Dated Logic allows the user to
recalculate TWA, SEL, DOSE and Projected
Dose using new Exchange Rate, Threshold,
and Criterion parameters during or after a
measurement.
u
d
l
r
m
Arrows:
Up, Down, Left and Right arrows are
used to change fields, to modify information
within a given field and can be used in con-
junction with other keys to allow other func-
tions.
Modify:
Prepares the field for changes while
in setup.
Keys
Functions
