Hi,
I’m currently planning some UWB localization tests on Channel 9 using a QM33120WDK1 evaluation kit.
In Germany, the maximum allowed mean EIRP spectral density for the frequency range from 6 GHz to 8.5 GHz is -41.3 dBm/MHz:
I noticed that SDK version 1.1.1 allows the TX power to be adjusted in the Qorvo UWB Explorer.
So my question is: Which TX Power Delta should I use to stay within the German regulations?
The kit includes two daughter boards:
The QM33110WEVB uses the QM33110W transceiver and the JL159 omnidirectional antenna. According to the datasheet, the maximum output power spectral density on Channel 9 is -32.5 dBm/MHz.
The QM33120WEVB uses the QM33120W transceiver and the JL359 directional dual antenna. According to the datasheet, the maximum output power spectral density on Channel 9 is -33.5 dBm/MHz.
I could not find any information about RF losses on the boards or the antenna gain of the JL159 and JL359 antennas. Because of that, I cannot estimate the final EIRP.
Could someone clarify:
Which TX Power Delta should be used for Channel 9 in Germany?
Are antenna-gain and RF-path-loss values available for the QM33120WDK1?
The answer is that it depends. Mostly on what exactly you are transmitting.
The regulations limit the power as measured averaged over a 1 ms period. Shorter UWB packets have a duration well under 1 ms. Which means the shorter the packet you send the higher you can set the transmit power, if you are off 90% of the time you can transmit at a far higher level and still be under the average limit.
When doing any power level testing you need to force the system to your worst case transmit situation. Generally that means sending the longest packet you support once per ms (or constantly if it’s over 1ms). If you could potentially transmit two packets within 1ms of each other from the same device then that could be worse than a single longer packet, you’d need to verify that situation too.
It can also depend on how you mount things. Your other electronics (and possibly housing) will distort the antenna pattern and may make it more directional, you need to test in the worst case orientation.
If you can make do with a pre-certified module with modular approval (which also means pre-certified UWB firmware) then do so. The approvals process is nasty, expensive and different enough from normal radios that you need to find a test house with UWB specific experience.
Fortunately most countries allow exceptions for product development / evaluation, without that how would anything ever get designed? As long as you aren’t causing any interference with other peoples equipment (you won’t be, the power levels even if you dial them up to max are tiny) and shut things down if there is any sign of causing interference then no one is going to give you any problems during a test and development phase.