FCC problem - Spectrum analyzer shows unwanted transmission when startup

[DreeOlee]

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.

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 Mary]

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]

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]

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

[DreeOlee]

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]

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

[DreeOlee]

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

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]

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]

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

[blubb]

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