DW1000 Bandwidth setting

Wireless Connectivity Ultra-Wideband
1

Hi,

We were calibrating our board for power and bandwidth.

We are using the following configurations.

Channel: 5
PRF: 16Mhz
Preamble length: 128

We are using the default register values for Bandwidth (0xC0) and Power (0x0E082848).

With default values we are expecting a power output of -41.3dBm(conducted ) and 10dB bandwidth of 499.2 mhz. But we are not getting the expected result.
What we are getting is -32dBm power and 700Mhz bandwidth.

We have done the same experiment with EVK(DW1000EVB) using the example code (ex_04b_cont_frame). But we are getting the same behaviour as above.

What could be the reason for this. Do we need to alter the register setting to obtain the expected output or is there a different way of measuring to get the expected output of power and bandwidth.

We referred to document APS023 for doing measurements in both the cases.

Regards,
Shijo Thomas

2

Hi Shijo,

I believe you’re transmitting continuous frames (non-stop back to back frames), whereas for certification testing you usually transmit a single frame per ms. So depending on your frame length, you could be maybe 7 dB higher than expected due to this.

I haven’t tested with PRF16 but with PRF64 (recommended setting 0x25456585), I find that the measured EIRP is usually quite near the -41.3 dBm/MHz limit. There’s a variation of ±2 dB due to the DW1000 IC. It also of course depends on your antenna gain, RF track layout on the PCB, etc., etc.

Are you measuring over the air or conducted?