nRF52840 transmission power limit & regulations

RE: nRF52840 transmission power limit & regulations

slowhand — Wed, 21 Jun 2017 05:51:31 GMT

Ok, thanks again!

RE: nRF52840 transmission power limit & regulations

slowhand — Tue, 20 Jun 2017 13:41:26 GMT

Thanks Jørn!

Good to hear that the value 8 is "legal" in Europe. I recall there was also a spectral density rule of 10mW/1MHz, but not sure if that applies/affects here.

Btw, did something happen with the 1Mbps mode since BT4.2? I mean I recall testing 1Mbps LE some years ago and the signal did not fly as far it does with nRF52840's 1Mbps mode. Not sure what the tx power was in the old test, though.

RE: nRF52840 transmission power limit & regulations

Jørn — Tue, 20 Jun 2017 13:13:46 GMT

Hello slowhand

From what I can see in ETSI EN 300 328 V2.1.1, ETSI sets an upper limit for non-adaptive equipment using Frequency hopping spread spectrum of 20dBm EIRP (100mW).

That is, with output power from the chip and gain from antenna combined. The nRF52840 can achieve a maximum of 8dBm, and its antennas have close to 0 dBi gain, meaning even with the output power set to maximum you should be well below the limit set by ETSI.

EDIT:

Your comment got me thinking and I conferred with a colleague. ETSI does in fact not define BLE as FHSS but as Direct Spread Spectrum (DSSS) due to the advertising channels, so it goes under the "other wide band modulation" section. The maximum output power is still the same for non-adaptive equipment, 20 dBm EIRP, but there is an additional power spectral density requirement as you said of 10mW/MHz. If I'm not completely off here, as each channel in BLE is 2MHz wide the nRF52840 should still be well within the specifications.

The Bluetooth 4.2 specification limits the output power to 10 dBm, and our previous chips had 4dBm maximum output power. In Bluetooth 5 that limit is raised to 20 dBm, and the nRF52840 is the first chip with 8dBm output power.

Best regards

Jørn Frøysa

RE: nRF52840 transmission power limit & regulations

slowhand — Tue, 20 Jun 2017 12:17:25 GMT

Ok, good. Anyway, testing (almost) anything that can't be productized is waste of time. Let's see if Nordic guys can give the number.

RE: nRF52840 transmission power limit & regulations

endnode — Tue, 20 Jun 2017 12:08:50 GMT

You don't need certification for prototype HW, only for commercially sold goods. So nothing illegal here.

RE: nRF52840 transmission power limit & regulations

slowhand — Tue, 20 Jun 2017 12:02:59 GMT

Perhaps so. Anyway, I am not looking for certification of the pdk. I am evaluating the capabilities of Bt5 technology, using the pdk. My evaluation is useless (and illegal) if I don't stay within the regulations. So, I should know which tx_power values I can use legally in my tests.

RE: nRF52840 transmission power limit & regulations

endnode — Tue, 20 Jun 2017 11:45:33 GMT

I guess PDK (or any other kit from Nordic) was never meant to be certified product which you can use in context of FCC or ETSI regulation.

RE: nRF52840 transmission power limit & regulations

slowhand — Tue, 20 Jun 2017 11:41:17 GMT

Sure, but I am not looking for certification. I am talking about nRF52840 pdk, usings the board's pcb antenna. The in-house knowledge is supposed to be in Nordic :-)

RE: nRF52840 transmission power limit & regulations

endnode — Tue, 20 Jun 2017 11:25:33 GMT

Normally you certify at the highest power setting so if you pass the lab test with that then you are safe. Compliance with local regulations like ETSI is quite alchemy so either you have the knowledge in-house or rather get some external consultancy during design phase (some cert. labs do this as part of the service package to customers).