Non adaptative FHSS - Maximum output power

RE: Non adaptative FHSS - Maximum output power

renkai-zeku — Fri, 27 Aug 2021 09:59:27 GMT

Hi Ketiljo,

Thank you for clarification of this question, however, I have two further questions and would like to hear your opinion.

1. I can't find any minimum 15 channels for adaptive FHSS and minimum 5 chaneels for non-adaptive FHSS on EN300328 V2.2.2, may I please ask you to provide the specific section about this?

2. As for adaptive non-FHSS, I noticed that most of the CE test reports for Bluetooth LE products are N/A, the reason for this is that RF output power of Bluetooth LE device, I guess, is lower than 10 dBm e.i.r.p because of the restriction of Power Spectral Density, and it's not required to perform Adaptivity test, am I correct?

RE: Non adaptative FHSS - Maximum output power

Aurele — Thu, 26 Nov 2020 21:15:38 GMT

Thank you very much for this detailed reply. It's clear enough now. So, i will stay at 10 dBm for now even if the hardware will be able to reach 20 dbm, it will allows me to test this feature. For the commercialization we will go with 10 dbm and hope that ETSI will change its rules in the future.

Thank you again

RE: Non adaptative FHSS - Maximum output power

ketiljo — Mon, 23 Nov 2020 13:31:57 GMT

Whether it's adaptive or not is not what decides what output power you can use. I assume it's BLE you're planning to use. This is not adaptive by design and won't be unless the protocol is changed. When you're in connected mode, BLE will use all 37 channels so the limitation will be the MU factor as you say. This is the maximum transmission time on _one_ channel.

But the problem is the advertisement channels. It's only three of them so it's not enough to satisfy the requirement of min 15 channels for adaptive FHSS and min 5 for non-adaptive FHSS. So the limitation will be the spectral density of 10 dBm / 1 MHz.

You could advertise at 10 dBm and increase the power to 20 dBm when you're connected. But if you loose the link, you have to set it back to 10 dBm. So the practical use is limited. So the bottom line is that you're limited to 10 dBm in Europe unless the ETSI standard changes or the number of advertisement channels are is increased to 5.