HT instruments HT154 - Manual (Page 8)

HT154
EN - 7
4.3. MEASUREMENTS
CAUTION
Wind blowing across the microphone would bring additional extraneous
noise. Once using the instrument in the presence of wind with speed higher
than 10m/s, it is a must to mount the windscreen to not pick up undesirable
signals. Keep the microphone dry and avoid sever vibration.
1. Turn ON the meter.
2. Performing calibration operation if the meter was not used for a long time using the
standard portable calibrator (see chapter 4.3.2).
3. Pressing A/C key to select the desired frequency weighing (see chapter 4.2.2)
4. Pressing FAST/SLOW key to select the corresponding time integration (see chapter
4.2.4).
5. Pressing LEVEL key to select the desired SPL range (see chapter 4.2.3).
6. Reading at display the measured SPL value.
7. If the message
OVER or UNDER are shown on the display, use LEVEL key to select a
higher or lower range respectively.
8. Pressing the MAX/MIN key to shows the Maximum or Minimum SPL value at display
(see chapter 4.2.5).
4.3.1. Connection to analogical AC and DC output
HT154 meter can be connected to accuracy multimeters and/or external data logger for
recording scope using the analogical DC or AC output (see Fig. 1) using 3.5mm coax plug
supplied as standard accessory. Technical specifications of output analogical are shown in
the herewith figure:
AC Output DC Output Signal
Ground
3.5mm output plug
¾
1Vrms at selected FS
¾
Output impedance: about
50 Ω
¾
Output: 10mV/dB
¾
Output impedance: about
100 Ω
Fig. 3: Description of analogical outputs