|= Abstract =|

Project Abstract: NEXUS v4.3.0

Environmental Monitoring & Atmospheric Attenuation in Chiropterology

"Precision machinist by trade, naturalist by heart."

Based in Paderborn, Germany, I developed the NEXUS system to bridge the gap between microclimatic data and bioacoustic reality. While I don't come from an academic background, my work is driven by the precision of a machinist and the curiosity of a field naturalist.

---

1. Executive Summary

The NEXUS (Network for Environmental eXtreme-precision Ultrasonic Sampling) is a modular, mobile monitoring platform designed to quantify how microclimates influence bat call propagation.

The core of the project is the real-time calculation of the atmospheric attenuation coefficient ɑ (Alpha) according to ISO 9613-1. By correlating high-resolution weather data with acoustic recordings, NEXUS helps to determine the true source level and effective range of bat calls under fluctuating environmental conditions.

---

2. The "Acoustic Bubble" Discovery

During the 2025/2026 validation phase, I identified a significant phenomenon I call the "Acoustic Bubble."

• Key Finding: At humidity levels >80%, the microclimatically induced EDR (Effective Detection Range) expands dramatically due to reduced atmospheric attenuation, especially in frequencies between 40–110 kHz.
• Result: This leads to exceptionally high-quality captures (AI confidence scores of 0.999 in BatDetect2) even at lower temperatures — which contradicts some standard assumptions in passive acoustic monitoring.

---

3. Calculation Basis: Atmospheric Attenuation (ISO 9613-1)

The NEXUS system calculates the absorption of sound in the atmosphere using the following formula:

Biological Significance:

For a high-frequency call (e.g., Rhinolophus hipposideros at 110 kHz), the value of ɑ can fluctuate between 0.8 dB/m and 2.5 dB/m depending on the microclimate. Over a distance of 10 meters, this results in an intensity loss of 8 dB to 25 dB, drastically affecting the probability of detection and the accuracy of AI classification.

---

4. Technical Specifications (Hardware)

• MCU: Seeed XIAO ESP32S3 (Dual-Core, 240 MHz)
• Sensors:
  • BME680: Precision temperature, humidity, pressure, and VOC (Bosch Sensortec)
  • AIR530 GPS: For micro-second time synchronization and WGS84 mapping
  • SparkFun SEN-15901: Wind speed, wind direction, and precipitation monitoring
• Compute: Real-time ISO 9613-1 calculations implemented in C++ (Arduino Framework)
• Integration: Designed to sync with TeensyBat recorders and TOPDON TS004 thermal imaging

---

5. Current Research: NEXUS-Cave

I am currently prototyping NEXUS-Cave to address the extreme conditions of high-density colonies (like Bracken Cave, TX). To bypass the physical limitations of standard microphones in corrosive, high-ammonia, and high-turbulence environments, this system utilizes:

• 24 GHz Radar-Logic for non-acoustic activity tracking
• 365 nm UV-Fluorescence for non-invasive Pd-detection (White-Nose Syndrome screening)
• Thermal Matrix Analysis to account for "Biological Wind" (vortex-induced microclimates)

---

6. Open Science & Data Exchange

The project follows Open Science principles. All data from the 2026 validation phase will be published on Zenodo under a CC-BY 4.0 license.

• Project Logs: Methodology documentation
• Raw Data / CSV Samples: Available upon request
• Collaboration: I am open to discussing data exchange and sensor-fusion strategies with international research teams