Does Bluetooth Channel Sounding Require Specific Radio Hardware Capabilities?

BL54L15μBL54L15BL54L10BL54LM20A SeriesBL54H20

Answer

Yes, Bluetooth Channel Sounding requires specific hardware features and hence not every BLE radio can do Channel Sounding. Below is a breakdown of why specific hardware is required:

1. New Hardware Capabilities

  • Unique Radio Requirements: The Channel Sounding (CS) feature mandates specialized hardware capable of performing Phase-Based Ranging (PBR) and Round-Trip Time (RTT) measurements.
  • Specific SoCs: Currently, this functionality is supported by next-generation SoCs like the Nordic nRF54L15/L10 and nRF54H20 series. Older BLE chips (e.g., nRF52 series) do not have the necessary radio circuitry to generate these specific tones or handle the precise timing required.
  • Antenna Requirements: For maximum accuracy, the hardware often requires dual-antenna support to perform angle-of-arrival calculations, which is not present in all BLE devices. 

2. Specialized Packet Formats and Tone Generation

  • CS Sync Packets: These are not standard advertising or data packets. They are specialized packets with cryptographic protections (using a dedicated CS Deterministic Random Bit Generator) used for synchronizing timing between the Initiator and Reflector.
  • CS Tone Packets: These are Amplitude Shift Keying (ASK) modulated tones used to measure phase rotation to determine distance. This requires specific analog radio hardware to generate and detect these tones rather than just typical GFSK modulation. 

3. Tight Timing Requirements

  • Channel sounding requires extreme timing precision to calculate distance via RTT (Time of Flight). The CS step involves rapid, bi-directional exchanges of packets and tones, often with very fast frequency hopping (T_FCS). This cannot be supported by traditional BLE firmware/hardware.