Happened RXSFDTO frequently when range


We use the chip DW1000 on my own PCB for ranging that the MCU of STM32L051 communicate with DW1000 through SPI. The tag MCU clock frequecy is 16MHz and spi baudrate is 8MHz, and the anchor MCU clock frequecy is 32MHz and spi baudrate is 16MHz. Now the ranging can be achieved between tag and anchor.
But there is ranging failures at the rate of 3% - 5%. The tag appears SYS_STATUS_RXSFDTO(0x04000000) in dwt_isr after sending poll when
failure, it seems that the tag has timeout waitting for response packed from anchor, however the anchor send the response packed after receiving poll when i debug the anchor.
Is there someone who know cause of the problem?

Thank you.
Best regards