3.1 Demo VRPR Software Application

The demo software application uses a separate software project and implementation for the Verifier node and the Prover node. These two software projects differ only at the application level and use the same driver for the UWB device and MCU peripherals. The verifier software controls the ATOLED1 display, and the UWB device operation initiates the distance measurement and performs the result calculation and display. The prover software initializes the UWB device in the Prover node and responds to the incoming verifier data telegrams. The following figure shows the measurement result on the ATOLED1 for the distance between the nodes in cm, the number of lost data packets since the start of the application and the clock offset between the Verifier node and the Prover node in ppm. The default mode is the VRo and PRo mode at the default channel A, which is 6.52 GHz.

Figure 3-1. ATOLED1 Measurement Data

In addition, a graphical view shows the leading edge position (small bar) and the position of the pulse maximum (larger bar). The position of the two bars gives an indication about the multipath reflections of the RF path between the Verifier and Prover nodes. If both bars are close together, a strong first path is detected (which might be a direct path or a multipath).

The measurement accuracy of ±45 cm is for one single measurement and can be improved by averaging, in other words, when performing measurements at different frequencies or at the same frequency or by evaluating the le_shift parameter at the Prover and the Verifier node. This is useful in localization applications where a higher accuracy is required. Performing averaging with several measurements improves accuracy but requires more measurement time and power consumption.

The clock offset measurement is required to compensate for clock differences between the Verifier and Prover nodes, which may result in distance errors of up to 300 cm if not compensated.

To evaluate this behavior, the kit may operate in two different distance measurement modes:

  • Distance-Bounding mode: The distance measurements are performed as single measurements, in other words, the distance differences up to ~±45 cm are observed between each measurement, but with optimal power consumption and measurement time.
  • Localization mode: The distance is an average value of 10 measurements, yielding measurement precision within ±10 cm, but with higher power consumption and measurement time.

After restarting the Verifier node, the selected mode displays on the start-up screen on the ATOLED1. The Prover node is not modified.

The software projects for the demo application are available with the following directory structure:

  • Demo Kit – Variant A:
    • Demo_Kit/SAMC21-XPRO/UWB_Demo7_VRPR/UWB_Demo7_Verifier.cpro
    • Demo_Kit/SAMC21-XPRO/UWB_Demo7_VRPR/UWB_Demo7_Prover1.cpro
  • Demo Kit – Variant B:
    • Demo_Kit/SAMC21-XPRO/UWB_Demo7_VRPR/UWB_Demo7_Verifier.cproj
    • Demo_Kit/ATAUWB-EK1_Prover/UWB_PR_Mode3/UWB_ Prover1.cproj
    • Demo_Kit/ATAUWB-EK1_Prover/UWB_PR_Mode3/UWB_ Prover2.cproj
    • Demo_Kit/ATAUWB-EK1_Prover/UWB_PR_Mode3/UWB_ Prover3.cproj
    • Demo_Kit/ATAUWB-EK1_Prover/UWB_PR_Mode3/UWB_ Prover4.cproj
    • Demo_Kit/ATAUWB-EK1_Prover/UWB_PR_Mode3/UWB_ Prover5.cproj