Scarlet Tech ST-25D User manual
ST-25D
User Guide
Sound Level Meter
ST-25D
Precaution
* Use the sound level meter gently, especially for microphone part, microphone is
delicate sensor that require careful handling, please avoid any crashing, knocking and
hitting, no water or oil entering.
* If choose to use alkaline batteries, please use high capacity of alkaline batteries. And
remember to remove the batteries when don’t use sound level meter for more than one
week.
* Do calibration before and after measurement if needed.
* Keep sound level meter powering on status at least 8 hours every month for charging
internal clock battery.
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Contents
1. General Introduction
2. Specification
3. Structure Features and Function
4. Preparation
4.1 Preparation before using
4.2 Use of windscreen
4.3 External power supply
4.4 Check and change battery
5. Calibration
5.1 Sound calibration Interface
5.2 Use ST-120 to calibrate
5.3 Directly input sensitivity level
5.4 Calibration record
6. Operation
6.1 Main menu
6.2 Measurement interface
7. Setup
7.1 RTC
7.2 Analyzer setup interface
7.3 Basic setup interface
8. Data Recall
8.1 Once measurement result
8.2 24H automatic monitoring result recallrecall
8.3 Integral measurement result recall
8.4 Delete data
8.5 Change to U-disk mode and recall
8.6 File Format Description
9. GPS Positioning Measurement
9.1 Distance measurement
9.2 Calibrate the RTC
9.3 GPS positioning measurement
10. Data Export
11. Overload Indication
12. Annex
12.1 Response characteristics
12.2 GPS overview
12.3 Filter attenuation characteristics
13. Safety, Handling, & Maintenance
General Introduction
Model ST-25D has advantages of low power dissipation, powerful function, friendly and
colorful display screen and abundant content. The instrument can measure A, C, Z
frequency weighting and F, S, I time weighting, and it can also measure multiple
assessment indexes at the same time. Its dynamic range is higher than 122dB.
The instrument enables statistics and integral analysis functions.
The design of low power dissipation and the automatic switchover of battery and the
external power can support the instrument to work for a long time. With embedded 32
MB flash memory turns ST-25D a reliable data logger. It also has a pre-installed 32GB
SD card for WAV recording function.
The instrument can be applied in environment protection, labor health, industrial
enterprise and research and teaching etc. It can also achieve measurement of environ-
mental noise, sound power level, machine equipment noise and building acoustics.
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Model ST-25D
Specification
2
Fulfils Standard
Normal Frequency
Measurement Range
Measurement Level
Resolution
Frequency Weighting
Time Weighting
Main Parameters of
Measurement
Datalogging
Audio recording
GPS
Bluetooth
Power Supply
Output Interface
Run Mode
Dimensions
Display
Graphic
Weight
Operation Environment
Package Contents
IEC 61672 Class 2 / IEC 61260 Class 2 / IEC61252:2002
20 Hz ~ 12.5kHz ± 1 dB (not including microphone)
28dB-133dB (145dB Peak)
Z(FLAT): 38 ~ 130dB / C peak: 145dB / Z(FLAT): peak: 145dB
0.1dB
A, C, Z parallel (synchronous)
F, S, I, parallel (synchronous), peak, Lin. Average
[Statistical] Lxyi, Lxyp, Lxeq, Lxymax, Lxymin, LxN, SD.
[Integral] Lxyi, Lxyp, Lxeq,t, Lxeq,T, Lxymax, Lxymin, Lxpeak, LAE, LC-A, SEL.
Note1: x is A, C, Z; y is F, S, I; LxN has five parameters, the user can define them and
N is chosen from 1 to 99.
Note2: 24H Measurement indexes：Ld, Ln, Ldn besides the indexes above
32MB Flash memory
48kHz, 32bit; 8kHz, 8bit
Location, Transport speed
Build-in; Support print measurement data
4 x AA Batteries or USB 5V external power supply
AC*, DC**, RS-232, USB
Key, Limit, Clock, Interval
260 x 80 x 30 mm
2.6-inch color display with 240*320 resolution
Statistic distribution graph, Accumulative distribution graph
0.35kg
Air temperature: - 15°C ~ + 55°C
Relative humidity: 20% ~ 90%
Sound Level Meter, Calibration Certificate, ½” Prepolarized Condenser
Microphone(Pre-installed), Windscreen, SD card(Pre-installed), RS-232 Cable, Mini
USB Cable, 5V Power Adapter, AA Batteries, User Manual, Waterproof Carry Case
*AC: Chosen between AC and 1 kHz. Its output can be connected to 8Ωearphone (output power: 150mW,
harmonic distortion: <0.1%).
**DC: Output the instantaneous sound pressure level of three frequency weighting (A, C, Z) and three
time weighting (F, S, I), output scale: 15mV/dB. For 100dB, its output voltage is 1.54V (sensitivity
level:-28dB)
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Structure Features and Function
The outline of the Sound Level Meter is shown in Figure 1. It consists of microphone,
preamplifier and the main unit. During normal operation, the measuring microphone
and the preamplifier are installed on the head of the main unit, connected with the
main unit through knurled nut. Extension cable can also be used between the main unit
and the preamplifier. The function of the connector’s pin between preamplifier and the
sound level meter is shown in Figure 2.
The outline of the sound level meter is sharp to reduce the reflection of the sound wave.
The nominal influence caused by the reflection on the shell and the indication features
under different incidence direction can be found in annexes. The shell is mold with ABS
plastic. The batteries are put in battery box, which is very convenient for users to
replace the batteries just by taking off the battery cover plate. All buttons are located
at the central of the obverse side. Measuring results are shown on the 240×320 OLED
display.
The GPS antenna slot, SD card slot and SD card indicator are located on the side, AC
output (3.5mm phone jack), GPS and Status indicator, RS-232 and mini USB port are on
the bottom of the device, the detail definition and function of pins is shown in the
following figures.
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Fig 1 Main structure
Microphone
Windscreen
GPS antenna port
Windscreen anti-drop hook
Preamplifier
Knurled nut
Display
Security slot
SD card indicator
SD card slot
(pre-installed a 32GB SD card)
Keypad
Mini USB port
Battery indicator
Status indicator
AC output
GPS indicator
RS 232
ST-25D
Fig 2 Preamplifier-Main device connector (X9 socket)
Fig 3 AC output (3.5mm phone jack/stereo socket)
Fig 4 Mini USB port
AC output signal’s amplitude won't exceed 1V. Its relationship with input signal is shown
in the table below:
5
Pin
1
2
3
4
5
6
Definition
Power supply
Not connected
Signal input
Not connected
Signal ground
Not connected
AC output
1
2
AC
input signal minus 10dB
input signal plus 10dB
AC
0.44V, 1kHz sine wave
0.7V, 1kHz sine wave
1. +5V
2. UD-
3. UD+
4. NC
5. GND
Fig 5 RS232 port
Fig 6 LED indicators
6
Pin
1
2
3
4
5
6
7
8
9
Definition
Power
RXD
TXD
Online
Ground
DC Output
Not connected
Not connected
Not connected
Working status
indicator
Working status indicator
LED behavior
Flashes
Static On
Off
Status
Measurement starts
Measurement paused
Measurement Stopped
GPS status indicator
LED behavior
Flashes in every 1 second
Off
Status
Positioning information is available
GPS module is not installed or in sleep mode
GPS status
indicator
ST-25D
Fig 7 Keypad
7
Name
On/Reset
Cancel
Left
Right
Up
Down
Set
Enter
Delete
Off
Output
Backlight
On/pause
Function
Power on; Restart the instrument
Move the cursor to left
Move the cursor to right
The value is added by 1; Page up; Change option
The value is deceased by 1; Page down; Change option
Enter the settings interface
Enter the current operation
Delete the current data or cancel the current operation
Power off the instrument
Finish the measurement ahead of time and save the measurement data
Turn on/off the backlight
Start or pause the measurement
Return to previous menu from the current menu
; Load the default parameters in the main menu interface
EnterCancel
Delete
On / Reset
Left Right
UpDown
Setup
Backlight
Start / Pause
OutputOff
Icon
Table of contents
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