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The device is a battery operated handheld instrument which provides 500ms and 200ms time weighted reading of sound level. Leq measurement can be done for a fixed time interval of 1-30 minutes, with one-minute resolution. A graphic LCD display shows the readings. Active filters are used for implementation of A & C weighting frequency characterization. Two selectable measuremet ranges are available - i.e. Low (40dB - 90dB) and High (80dB - 130dB).The device is also equipped with non-volatile storage which can store measured values with time tag of one second resolution for a maximum duration of 30 Mins.
Sound Level Meter (SLM-04) has been designed and manufactured by the manufacturing vertical of Webel according to the specification outlined by West Bengal Pollution Control Board. This is a type-2 sound level measuring instrument, useful for measurement of sound / noise level at public place, factories, workspace, etc. having facility for instant printing of noise level measured along with date, time and location information.
Noise Pollution or Sound Pollution is the propagation of excessive level of noise in the environment with harmful impact on health. Some of the sources of noise in residential areas include loud music, fire crackers, transportation, indiscriminate use of loud speakers in high volume in public events, etc. In factories, machines cause high level of noise.
Noise exposure has been known to induce sleep disturbance, headache, annoyance, fatigue, tinnitus, hypertension, heart disease and even hearing impairment.
Through Acts of Government of India permissible limits are defined for different areas like residential, industrial, commercial and silence zone. Silence zones are places around hospitals, schools, courts, etc. Day time and night time limits are also defined by the Pollution Control Board.
Law enforcement agencies required field instrument to measure and record noise level at sites along with date, time and location information.
WML has completed training and distribution of the devices to the various Police Commissionerates across the state as per the distribution list suggested by the West Bengal Pollution Control Board.
| Sl | Item | Specification |
|---|---|---|
| 1 | Display | LCD Graphic Display |
| 2 | Measurement | a) NOISE LEVEL Output in dB (A & C frequency weighting) Time weighting (Fast = 200ms ; Slow = 500ms) b) LEVEL EQUIVALENT (Leq) Energy-averaged noise level, over programmable time duration with 1 minute resolution, maximum upto 30 minutes |
| 3 | Measurement range | 40 to 130 dB (only input) in two slots Low : 40 – 90 dB High : 80 – 130 dB |
| 4 | Resolution | 0.1 dB |
| 5 | Accuracy (23 ± 5⁰C) | Calibrating at 94dB with IEC 651 type 2, Accuracy = ±1.5dB at 1KHz F.W. |
| 6 | Frequency weighting network | A weighting : Human ear listening response C weighting : Flat response |
| 7 | Frequency | 20Hz to 20KHz |
| 8 | Microphone | Electronic Condenser Microphone with -34 dB Sensitivity |
| 9 | Time weighting: (Fast & Slow) |
Fast (t = 200ms) and Slow (t = 500ms) |
| 10 | Calibration | Easy instrument (e.g., screw driver) with externally fitted calibrator |
| 11 | GPS / GSM | Onboard GPS Module to have Location, Date & Time information of the place of measurement. Location : in Latitude & Longitude up to second ( “ ) precision Date : DD:MM:YYYY format Time: HH:MM:SS format |
| 12 | Recording & Data uploading | Data can be recorded for a duration of ½ an hour. Data can be uploaded to a host computer through built in USB interface. |
| 13 | Printer | Onboard miniature thermal printer for taking print out of the measurement data along with the Location, Date and Time information. Instant Printing through dedicated key switch. Thermal paper roll width : 2” |
| 14 | Operating condition | 0 to 45°C temperature and 90% relative humidity (non- condensing) |
| 15 | Power supply | Built in 7.4V Rechargeable Battery Pack |
| 16 | Others | Carrying case + Battery Charger |
| 17 | Weight | 675 gm (approx) |