XHSN-301 Environmental Noise Automatic Monitoring Station

Overview

The XHSN-301 Environmental Noise Automatic Monitoring Station is a permanently installed, continuous noise monitoring system engineered for long-term, unattended operation in outdoor urban and industrial environments. It operates on the principle of precision electret condenser microphone transduction, compliant with IEC 61672-1:2013 Class 1 performance requirements for sound level meters. The instrument captures broadband acoustic signals across a full 10 Hz to 20 kHz frequency range, applies real-time A-weighting per ISO 8596 and ANSI S1.43, and computes statistically weighted metrics—including L_Aeq, L_AFmax, L_AFmin, L₁₀, L₅₀, L₉₀, and percentile distributions—according to ISO 1996-2:2017 and EU Directive 2002/49/EC (END). Its integrated environmental sensor suite enables simultaneous acquisition of ambient temperature (±0.3 °C), relative humidity (±2 % RH), and atmospheric pressure (±0.1 kPa), supporting meteorological correction of noise propagation models in accordance with CNOSSOS-EU guidelines.

Key Features

• Class 1-compliant electret condenser microphone with thermal and humidity-stabilized preamplifier, ensuring stable sensitivity over extended deployment cycles
• Modular hardware architecture: acoustical unit, environmental sensor module, GPS/4G communications board, and power management subsystem are independently replaceable
• Embedded GPS receiver providing geotagged measurement metadata with ≤3 m horizontal positional accuracy (CEP), essential for source attribution and spatial interpolation in noise mapping applications
• 4G LTE-M/NB-IoT capable modem with dual-SIM failover support, enabling secure TLS 1.2 encrypted data transmission to centralized servers via MQTT or HTTP(S) protocols
• Remote calibration verification and adjustment via reference tone injection through internal acoustic calibrator—eliminating requirement for on-site physical calibrator deployment
• Ruggedized IP65-rated enclosure with UV-resistant polycarbonate housing, operating temperature range: −25 °C to +60 °C, suitable for permanent outdoor mounting on poles, rooftops, or façades

Sample Compatibility & Compliance

The XHSN-301 is designed for continuous monitoring of ambient sound pressure levels in open-air environments. It complies with national and international regulatory frameworks governing environmental noise assessment, including China’s HJ 972–2018 Technical Specification for Automatic Monitoring of Environmental Noise, EU END Annex II measurement methodology, and ISO 1996 series standards. All firmware and data logging routines adhere to GLP-aligned audit trail requirements: each measurement record includes timestamp (UTC), GPS coordinates, sensor status flags, calibration history, and digital signature for data integrity verification. Raw audio snippets (optional) are stored locally in WAV format at 48 kHz/24-bit resolution for forensic analysis upon request.

Software & Data Management

Data acquisition and remote configuration are managed via a web-based platform supporting role-based access control (RBAC), multi-tenancy, and customizable alerting (SMS/email/webhook) based on user-defined thresholds. The system supports export of time-series datasets in CSV, NetCDF4, and standardized ENM (Environmental Noise Monitoring) XML schema formats. Audit logs retain full traceability of all configuration changes, firmware updates, and calibration events in compliance with ISO/IEC 17025:2017 clause 7.7 and FDA 21 CFR Part 11 electronic record requirements. Historical data is retained for ≥12 months with automatic tiered archiving to cloud storage.

Applications

• Urban noise mapping for municipal strategic noise mapping (SNM) programs under EU Directive 2002/49/EC
• Long-term monitoring of noise exposure in residential zones adjacent to highways, railways, airports, and industrial facilities
• Construction site noise compliance verification against local ordinances (e.g., L_Amax limits during nighttime hours)
• Acoustic impact assessment for environmental impact statements (EIS) and permitting workflows
• Real-time public information displays at city kiosks or municipal websites, showing live L_Aeq,1h and trend indicators
• Integration with smart city infrastructure platforms via RESTful API for cross-domain analytics with traffic, air quality, and weather data streams

FAQ

Does the XHSN-301 meet international Class 1 sound level meter standards?
Yes—it conforms to IEC 61672-1:2013 Class 1 specifications for electro-acoustical performance, including frequency weighting, time weighting, linearity, and environmental influence testing.
Can it operate without external power for extended periods?
It requires continuous DC 12–24 V power input; solar-battery hybrid configurations are supported via optional external power management module.
Is raw audio recording available for post-event analysis?
Optional firmware enables triggered or scheduled 10-second WAV file capture synchronized with exceedance events, stored locally on microSD card.
How is data security ensured during wireless transmission?
All telemetry uses TLS 1.2 encryption; device authentication employs X.509 certificates; no default credentials are shipped with the unit.
What maintenance intervals are recommended for field deployment?
Microphone diaphragm inspection and windscreen replacement every 6 months; full system functional verification annually per HJ 972–2018 Section 7.3.