FCC problem - Spectrum analyzer shows unwanted transmission when startup

DreeOlee
Posts: 8
Joined: Wed Jan 10, 2018 6:19 pm

FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby DreeOlee » Wed Jan 10, 2018 9:31 pm

Hello everyone,

This is my first post at this Forum. Hopefully someone can help/support me with this urgent issue.

The problem is that the module shows a lot of unwanted transmissions during start-up, causing the FCC certification to fail.
Analyzer_Screenshot_Startup_ESP8266.png


As the attachment shows, the transmissions are unexpected and not inside the FCC regulations. According the FCC, transmissions outside the blue lines are not allowed.

> I'm using the ESP-WROOM-02 module.
> Latest SDK (also tried previous versions)
> Even deleted every WiFi SDK link, without success
> Try starting up with WiFi disabled, no success
> Tried different power supplies, no success
> The phenomenon is also visible during a restart from deep sleep
> After restart, so from the first line of the initialization/setup(), I have full control without issues.

At this moment I'm out of ideas how to solve this problem. I expect it's a ESP hardware issue, but not sure.

Is there anyone who can help me with this or is there anyone who have seen this problem before?

Greetings,
DreeOlee

Her Majesty
Posts: 305
Joined: Mon Oct 27, 2014 11:09 am

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby Her Majesty » Thu Jan 11, 2018 6:02 pm

Espressif provided an FCC firmware on their website http://www.espressif.com/en/support/download/other-tools.
You can download and test the "ESP8266 Certification and Test".

DreeOlee
Posts: 8
Joined: Wed Jan 10, 2018 6:19 pm

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby DreeOlee » Thu Jan 11, 2018 8:32 pm

I just downloaded the ESP8266_FCC_26m_20170731.bin file, and the result is exactly the same. Directly at power-up and just ones.

blubb
Posts: 100
Joined: Mon Jun 22, 2015 5:35 am

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby blubb » Fri Jan 12, 2018 7:13 am

Have you tried the API mentioned here?
viewtopic.php?f=7&t=8768

DreeOlee
Posts: 8
Joined: Wed Jan 10, 2018 6:19 pm

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby DreeOlee » Fri Jan 12, 2018 5:12 pm

Yes I also tried that. In fact, that was our original problem. We made a change in the API and now we had full control over the ESP. But still the problem appears with switching the device on.

It happens only at startup. Just a fraction of time, after that there is no problem. The time is that short, that the spectrum analyzer not always captures the signal.

blubb
Posts: 100
Joined: Mon Jun 22, 2015 5:35 am

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby blubb » Fri Jan 12, 2018 6:08 pm

Do you call this API in user_rf_pre_init or in user_init? I wonder if that makes a difference.

DreeOlee
Posts: 8
Joined: Wed Jan 10, 2018 6:19 pm

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby DreeOlee » Fri Jan 12, 2018 10:47 pm

In the user_init. Tried also in the user_rf_pre_init without result.

The problem occurs before the user_rf_pre_init. I commented everything out in the user_rf_pre_init, user_init and the init_done. Strange btw is that after this, I got more debug info on my serial line :D


Code: Select all

 ets Jan  8 2013,rst cause:2, boot mode:(3,0)

load 0x4010f000, len 1384, room 16
tail 8
chksum 0x2d
csum 0x2d
v00000000
~ld
rf cal sector: 508
freq trace enable 0
rf[112] : 00
rf[113] : 00
rf[114] : 00

SDK ver: 2.1.0(deb1901) compiled @ Oct 23 2017 17:58:03
phy ver: 1136_0, pp ver: 10.2

mode : null


I still have the problem.

blubb
Posts: 100
Joined: Mon Jun 22, 2015 5:35 am

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby blubb » Fri Jan 12, 2018 10:52 pm

I recommend opening an issue on github
https://github.com/espressif/ESP8266_NONOS_SDK/issues

Edit:
There are several APIs like
system_phy_set_powerup_option(...);
system_phy_freq_trace_enable(...);
But if the problem occurs before user_rf_pre_init this is a case for a github issue for sure.

DreeOlee
Posts: 8
Joined: Wed Jan 10, 2018 6:19 pm

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby DreeOlee » Fri Jan 12, 2018 11:08 pm

okay thank.....I will place it directly.

blubb
Posts: 100
Joined: Mon Jun 22, 2015 5:35 am

Re: FCC problem - Spectrum analyzer shows unwanted transmission when startup

Postby blubb » Sat Jan 13, 2018 8:51 am

Maybe one more idea:
Did you flash the latest esp_init_data_default.bin?
Recently they changed something, so there is a new version "8":
https://github.com/espressif/ESP8266_NO ... master/bin

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