Advertisement
3.5 Power On/Off
Press
to power on the SP79.
To power off the SP79 press and hold
decreased to zero, at which point the unit will power off.
3.6 Auto Power Off
If the unit is inactive for a period of 30 minutes it will automatically
power off.
To disable this function hold down the
the SP79. The
symbol will no longer be displayed on the LCD.
3.7 Frequency Weighting
The SP79 powers up with A - weighting selected. The LCD displays
dBA.
To set to C - weighting, press
A/C
Press
A/C
again to return to A - weighting.
A - weighting is used for general sound level measurements.
C - weighting is used for checking the low-frequency noise content.
Note: If the C-weighted level is much higher than the A-weighted
level, then there is a large amount of low-frequency noise.
3.8 Time Weighting
The SP79 powers up with fast weighting selected. The LCD displays
FAST.
To set to slow weighting, press
FAST
Press
again to return to fast weighting.
SLOw
Set to fast weighting for normal measurements.
The SP79 should be tested against a sound calibrator with a 94dB
1kHz reference level, and if required adjusted to correctly display
the certified value of sound calibrator.
A suitable sound calibrator is the Martindale SPC70.
To perform the test, hold down
MAX
The LCD will display CAL 94dB flashing.
Insert the microphone of the SP79 into the microphone well of the
sound calibrator, ensuring the microphone is correctly seated.
Power on the sound calibrator and read the displayed sound level
reading on the SP79 LCD.
If required press
or
to increase or decrease the SP79
reading until it agrees with the certified value of the sound
calibrator, taking into account any corrections for ambient conditions
for the sound calibrator.
MIN
Press
to complete the adjustment.
MAX
To abort the test, press
.
3.12 Sound Level Measurements
Press
to power on the SP79.
Select the required time and frequency weighting. The SP79
defaults to FAST and A respectively at power up.
If the sound source consists of short bursts, set the time weighting
to FAST. To measure average sound level, use the SLOW setting.
For general noise sound level measurement set the frequency
weighting to A. To measure the sound level of acoustic material,
use the C setting.
Set the required level range using the
until the bargraph has
FAST
button when powering on
SLOw
. The LCD displays dBC.
FAST
. The LCD displays SLOW.
SLOw
MIN
when powering on the SP79.
buttons.
Set to slow weighting for checking the average level of fluctuating
noise.
3.9 Min/Max
To display the maximum measured value press
display MAX.
To display the minimum measured value press
will display MIN.
MIN
Pressing
for a third time will return the meter to a normal display
MAX
mode with maximum and minimum measured values being stored.
The LCD will display MIN MAX flashing.
To exit the Min/Max function, press
Note: If the sound level range or the frequency weighting is changed,
the SP79 will exit the Min/Max function.
3.10 AC/DC Output Socket Connections
If required a frequency analyzer, level recorder, FFT analyzer,
graphic recorder, etc. may be connected to a standard 3.5mm
coaxial socket that provides both AC and DC signal outputs.
3.11 Adjustment using Sound Calibrator
Most noise testing regulations and guidelines require that your sound
level meter is tested using a sound calibrator before use. In any
case, it is good practice to test the SP79 against a sound calibrator
before and after use to be sure it has not been damaged or is not
faulty.
7
8
Referring to 3.13 (Measurement Considerations), point the SP79
microphone at the noise source to be measured and read the
measured sound level from the display.
UNDER
OVER
If
or
and re-read the measured sound level from the display.
If required, the SP79 can be mounted on a tripod.
3.13 Measurement Considerations
Outdoor noise measurements should be made on a day with a calm
to gentle breeze, and not be made in the rain.
If wind is blowing across the microphone, attach the windscreen to
the microphone.
The best method when making sound level measurements is to
mount the SP79 on a tripod, and to allow sufficient clearance to
minimize any sound reflections from the user's body.
If the SP79 is held by hand, it should be held out to the side of the
body at arm's length to minimize any sound reflections from the
user's body.
The microphone should be placed well away from reflective
surfaces such as walls or the floor, in order to eliminate errors
caused by reflections.
Make sure the noise source is not obstructed.
9
10
MIN
. The LCD will
MAX
MIN
again. The LCD
MAX
MIN
for 2 seconds.
MAX
is displayed on the LCD, reset the level range
Advertisement
