Posted on by haowenhu

Haowen’s Weekly Status Report (Week 5)

Executive Summary

This week, I conducted in-depth feasibility research on our BLE 5.1/5.2 Angle of Arrival (AoA) tracking pipeline, clarified the system data flow across team roles, and validated the hardware stack integration plan for our incoming components.

By offloading raw microwave-frequency switching and phase demodulation directly to dedicated silicon, we confirmed a low-complexity architecture that avoids sub-nanosecond FPGA timing constraints while delivering reliable angle metrics.

Key Accomplishments This Week

1. Architecture Research & Technical Feasibility

  • Silicon-Level AoA Offloading: Researched the Nordic nRF5340 + u-blox ANT-B10 hardware pipeline. Confirmed that the nRF5340 Network Core executes CTE (Constant Tone Extension) I/Q sampling natively in silicon via Nordic’s direction_finding_connectionless_rx SDK module, outputting processed scalar angles over UART rather than raw high-frequency RF vectors.
  • Comparative Trade-off Analysis: Evaluated alternative approaches (e.g., direct FPGA RF sampling and UWB). Concluded that 2.4 GHz BLE AoA using our off-the-shelf kit provides the optimal balance of power, cost, and reduced timing complexity for a water/poolside environment.

2. System Data Flow & Team Alignment

  • Wearable vs. Base Station Setup: Clarified the hardware topology across Signal, Hardware, and Software sub-teams:
    • Wearable Tag (Swimmer): A lightweight transmitter (Pico + BLE radio emitting standard CTE frames) with no heavy compute overhead.
    • Base Station (Poolside): Fixed u-blox ANT-B10 8-antenna array connected to the nRF5340-DK, streaming angle scalars over a 3-wire hardware UART link (TX, RX, GND) at 115200 baud to the processing core.
  • Multipath Noise Strategy: Designed a two-stage embedded filtering pipeline (Median Filter for splash outlier removal + Moving Average for trajectory smoothing) to mitigate surface water reflections.

3. Development Setup Preparation

  • Unboxed arriving hardware components (nRF5340-DK, u-blox ANT-B10, Pico WH) and prepped the nRF Connect SDK environment for VS Code.

Next Week’s Goals (Planned Tasks)

  1. Hardware Benchmarking & “Hello World” Test: Assemble the ANT-B10 board onto the nRF5340-DK, flash the official SDK sample code, and verify raw Azimuth/Elevation scalar outputs via a serial terminal during walking tests.
  2. UART Pipeline Integration: Wire the nRF5340-DK to the Pico WH over hardware UART and establish basic packet receiving logic.
  3. Draft UART Packet Protocol: Define the binary/JSON payload structure for streaming filtered coordinates downstream to the Software team’s dashboard.