DWM3000 power spectral density


In order to determine the maximum transmission power or the maximum value for the TX_Power register, we have determined the RSSI in dBm at a very short distance. (Formula in the user manual). Since we are limited to 41.3dBm / Mhz transmission power spectral density, RSSI / MHz has to be determined, so that, according to my considerations, this value is 27dBm lower due to the 500MHz bandwidth. At a distance of ~10cm we are at RSSI ~ 43dBM and respectivly RSSI / MHZ ~ 70dBM. But we have already chosen the transmission power to be very high: TX_POWER register = 0xFDFDFDFD (tx power level ~ -3dB)
Configuration: ch = 9, preamble = 64, PAC = 8, TX&RX preamble code = 9, standard 8 symbol SFD, 6.8Mbit / s data rate, no STS.
Our questions: Are our assumptions correct? Has the 500MHz bandwidth already been taken into account in the calculations?
Because we don’t come close to -41.3dBm/MHz.
Thanks in advance!

You can’t trust the RSSI value when calculating your total transmit power for regulatory reasons. If nothing else the regulations are averaged over a 1ms time period, the RSSI is not.
You need to use a spectrum analyser, ideally with a 500MHz bandwidth, set to give the appropriate 1ms average and connected to a known calibrated rx antenna. You then put your device into a mode where it transmits it’s worst case transmissions over a 1ms period (or if your packets are longer than than 1ms, transmit constantly). You then need to rotate the device to find the direction with the highest gain, the limits are for the peak direction not the average or typical direction.