UNI-T UT353 BT Mini Sound Level Meter (Bluetooth Technology) Manual

I. Introduction

The UT353 BT is a safe and reliable sound level meter with stable performance and Bluetooth communication function, making it easier to use. It is widely used for measuring and monitoring noise in relation to noise engineering, quality control, health monitoring, and other environmental noise measurements, such as in factories, streets, and stereo systems.

ATTENTION: Please read the "Safe Operating Criteria" carefully before using the product.

II. Unpacking Check

Open the carton, take out the device, and carefully check if there are any missing or damaged items:

• 1. Blister
• 1. Windproof ball
• 1. Manual

III. Guidelines for Safe Operation

The instrument is designed and manufactured strictly according to the requirements of SJ/T 10423 Sound Level Meter General Technical Conditions.

1. Before using the instrument, check for damage or unusual appearance. If the device casing is significantly damaged, the LCD display does not show anything, or you believe the meter is not functioning, do not use the meter.
2. Follow the instructions when performing measurements.
3. Do not open the instrument arbitrarily, and do not modify the internal wiring of the meter to avoid damaging the device and compromising safety.
4. When the LCD displays low battery indication, the batteries should be replaced to ensure measurement accuracy. If the power clamp is not used for a long time, remove the batteries.
5. Do not use the meter in environments with high temperatures, high humidity, flammability, explosiveness, and strong electromagnetic fields.
6. Clean and maintain the clamp housing with a soft cloth and a neutral cleaning agent. Do not use abrasive materials or solvents to prevent corrosion of the shell, damage to the instrument, and safety hazards.
7. The product is CE certified.

IV. External Structure

1. Windproof ball
2. Condenser microphone
3. Device casing
4. LCD display
5. Function keys

V. Display Symbols

1. MAX MIN HOLD

• 1. Measurement display of maximum value
• 2. Measurement display of minimum value
• 3. Data hold display
• 4. Low battery indicator
• 5. A-weighting and noise unit
• 6. Slow response rate indicator
• 7. Fast response rate indicator
• 8. Measured value
• 9. Bluetooth communication symbol display

VI. Button Functions and Settings

(Note: Short press: quasi 1 second; Long press: quasi 2 seconds)

1. Power On/Off/Bluetooth Communication
   • Power On/Off: Short press to turn the device on, and press again to turn it off.
   • Bluetooth Communication: When the device is on, press and hold the button to enter Bluetooth communication mode. Press and hold again to exit Bluetooth communication mode.
2. FAST/SLOW: Fast/Slow Response Selection
   • Unit Conversion Button: During noise measurement, short press this button to select between a fast rate of 125 milliseconds and a slow rate of 1 second.
3. MAX/MIN: Maximum/Minimum Value Selection
   • MAX/MIN: Maximum/Minimum Value: During noise measurement, short press this button to select maximum, minimum, and normal measurement. When the maximum or minimum value is selected, the maximum or minimum values will always be displayed.
4. HOLD/BL: Data Hold/Backlight
   • HOLD-Data Hold: During noise measurement, short press this button once to hold the measured value. Press the button again to stop data measurement and continue normal measurement.
   • BL-Backlight: Long press the button once to turn on the backlight, and then long press again to turn off the backlight.
5. Automatic Shutdown
   • When the device is generally powered on, if there is no operation for 5 minutes, the device will automatically shut down (the default mode is automatic shutdown). If you want to disable the automatic shutdown mode, press and hold the "HOLD" + "BL" button in the off state. The "APO OFF" symbol will appear on the LCD display, indicating that automatic shutdown is canceled.

VII. Bluetooth App Description

1. To activate Bluetooth connection, you need to install the application on a smartphone, the iENV APP.
2. For iOS devices, you can get the application from the App Store. For Android devices, get it from the Play Store or visit the official Uni-Trend Technology (China) GmbH website at www.uni-trend.com to download it.
3. Compatibility:
   • iOS version 8.4 or higher (iPhone 5S or more)
   • Android version 4.3 or higher
   • Bluetooth 4.0 or higher
   • 1G memory or higher
4. When connecting the Bluetooth app with the product, you must turn on Bluetooth, search for the product's Bluetooth with the APP, and perform the selection of the corresponding product in the iENV App to connect.
5. When the product is turned on, long press the power button once to activate or deactivate Bluetooth.
   • a. If the product's Bluetooth symbol is blinking, it means the product is not connected to the app.
   • b. If the product's Bluetooth symbol is not blinking, it means the product is connected to the app.

Connecting the App with the Product

Search for Product Bluetooth via App

iENV

Connected to the device:

66.4 dBA FAST

Device in transmission mode: UT353BT

20:91:48:6C:83:2D

iENV

Connected to the device:

Device in transmission mode: UT353BT

20:91:48:6C:83:2D

1. Technical Data

• Measurement Range: 30 ~ 130dB
• Resolution: 0.1dB
• Accuracy: ± 1.5dB
• Frequency Response: 31.5Hz~8KHz
• Ambient Temperature: 23°C ±5℃
• Humidity: ≤80%RH
• Temperature Coefficient: 0.1 × (Accuracy)/°C

2. General Specifications

• a. Liquid Crystal Display: 4-digit liquid crystal display, maximum display "130.0"
• b. Overload Display: "UN" is displayed below the range; "OL" is displayed above the range.
• c. Low Battery Indication: Symbol ?
• d. Sampling Rate: 125ms fast, 1 second slow
• e. Sensor Type: 1/2 inch condenser microphone
• f. Shock Resistance: Can withstand 1m drop onto the ground
• g. Power Supply: 3×1.5V batteries (AAA)
• h. Power Consumption: After Bluetooth is turned on, it can work continuously for more than 12 hours.
• i. Dimensions: 154mm*55mm*28mm
• j. Thread Specifications for connecting products and tripods:
• k. Weight: 116g

3. Environmental Requirements

• a. Indoor use
• b. Altitude: 2000m (maximum)
• c. Pollution Degree: 2
• d. Operating Temperature and Humidity:
  • 0℃~30℃ (not more than 80%RH)
  • 30°C~40℃ (not more than 80%RH)
  • 40°C~50℃ (not more than 45%RH)
• e. Storage Temperature and Humidity:
  • -20°C~60°C (not more than 80%RH)

4. General Maintenance

Attention: Do not open the device casing to avoid affecting accuracy or damaging the device.

• a. Maintenance and servicing of the meter must be performed by qualified professional service personnel or a designated maintenance department.
• b. Periodically clean the casing with a dry cloth, but do not use cleaning agents containing abrasive components or solvents.

5. Install or Replace Batteries

• a. The power supply for this product is three 1.5V alkaline batteries (AAA). Install or replace the batteries according to Figure 3 below.
• b. With the product panel facing down, pull the battery cover off in the direction of the arrow, remove the battery, and follow the polarity instructions to install the new batteries.
• c. Use batteries of the same type; do not install unsuitable batteries.
• d. After installing new batteries, reattach the battery cover and secure the screws.