2-6
Understanding the Model 820 Keypad
Model 820 Technical Reference Manual
B
L
N
:
The L
n
values represent the SPL
exceeded n% of the run time. All values from
1% to 99% are available, four or six of these
are displayed at a time and can be changed
even while running.
BATT:
This key gives the percentage of
power remaining in the 9 V battery, or exter-
nal supply.
BATT-b
: Gives Model 820 revision number
and date.
T
L
EQ
:
The Equivalent Level or L
eq
is a Time
Weighted Average based on an exchange rate
of 3dB (true energy measure) with no thresh-
old.
Time:
The date and time of last reset or mea-
surement start are available from the Time-a
display. The current date and time are shown
with the Time-b display.
t
SEL:
The Single Event Level or Sound Expo-
sure Level is an energy reading in decibels. It
is the TWA level plus 10 times the log of
measurement time in seconds.
SEL-b
: Gives exposure in Pa2H which is a
linear representation of energy.
TIMER:
The ability to take a measurement at
a specific time and date is available, thus per-
mitting unattended measurements, i.e. one or
two measurements/day between two dates or
a single block measurement from a start date
and time to a stop date and time.
Keys
Functions