Hello,
I am measuring RX power using two DW1000 devices (anchor and tag) placed at a distance of approximately 40 cm. I observed a significant difference in reported RX power depending on the PRF configuration.
Below are my measurements:
Configuration 1:
- Data rate: 6.8 Mb/s
- PRF: 16 MHz
- Preamble length: 1024
- Channel: 5
RX power:
- -55.46 dBm
- -56.07 dBm
- -54.68 dBm
Configuration 2:
- Data rate: 6.8 Mb/s
- PRF: 64 MHz
- Preamble length: 128
- Channel: 5
RX power:
- -86.62 dBm
- -86.40 dBm
- -86.46 dBm
Configuration 3:
- Data rate: 110 kb/s
- PRF: 16 MHz
- Preamble length: 2048
- Channel: 5
RX power:
- -56.87 dBm
- -56.33 dBm
- -56.70 dBm
- -57.74 dBm
At this short distance (~40 cm), the values around -55 dBm seem physically reasonable. However, when using 64 MHz PRF, the reported RX power drops significantly to around -86 dBm, which appears too low.
From the application note APS011: Sources of Error in DW1000-Based Two-Way Ranging (TWR) Schemes, it is stated that around -77 dBm at 5 m corresponds to zero range bias error. This is why I am investigating RX power behavior for calibration purposes.
My questions:
- Why does the RX power appear significantly lower when using 64 MHz PRF compared to 16 MHz PRF at the same distance?
- How can I obtain accurate RX power measurements when using 64 MHz PRF?
- Is there a recommended correction or calibration method for RX power at different PRFs?
Any insights or references would be greatly appreciated.
Thank you.