For verification, you can fix the working channel of AP then record it. Next time you met the situation you can check the channel now and compare it to the original one.

As for retrieve a log to remind you that there is a radar channel, I think it makes no sense.
When AP detect a radar signal, it will shift to another channel automatically until the channel is not used by radar, all the thing you need to do nothing but wait.
Even if you know that AP met the radar, how can you do? Nothing but wait. So the log doesn't do any help.
How do you think that the TP-LINK officer will add such function just for your personal learning purpose?

BTW: I've try to change the region in my CPE510 to Spain, I find the working channel is 100~136, which all need DFS in your country. So it's takes long time to wait for AP signal when the begin configuration.

Haha, @cr2. :cool:

Not 15 minutes, it should be 10 minutes after boot up as required by ITU-T Radio Regulations.

In fact they issue an article which can answer your question. http://www.tp-link.com/en/faq-763.html

Whether radar is detected or not, it is required to detect for 10 minutes for 5600~5650MHz after bootup and before transmission, which covers channel 120/124/128, channel 116 is also affected in 40MHz HT mode.

For other channels available in Spain, the detecting duration is 1 minutes. You can try those channels for a shorter wait.

It is easy to judge whether radar signal occurs. If radar is detected during transmission, the link will break up and the APs will begin CAC detection again as required......

Thanks both for the valuable information.

@stupidbird - I've seen such situation, fixing a specific channel in the configuration and after a while the communication switched to a different one, thanks to you I know now the possible cause and the possible way to troubleshoot it, but I still think it is not a time-efficient way to find out the best radar-free channel out there. I still think a more detailed log for this purposes should be available to the user, I'm 99% sure that the log has more details internally than shown to the user, but I guess the level of verbosity should be changed somehow, I tried connecting through ssh to do it but I couldn't guess how...

@Tobacco - Thanks, I had seen the link and I read it several times before asking but now, as explained in your words I understand better the small note mentioning the time not being able to detect the AP. I'll probably switch to one of the channels with one minute wait.

I'm still interested in a more detailed log information, anyone knows how to access it? I can't access the folder /var/log through ssh? may be there is something there...

I don't know how to access those info. (Actually I am not sure it has output of DFS information or not, even if it has output, I think it is output after some specific commands rather than written in log file.)