Wi-Fi RF characteristics are not stable over temperature variations
Posted: Thu Oct 05, 2017 7:55 am
Hello,
when testing RF tx characteristics at different temperatures we see that the output power and EVM values drift out of spec.
Ambient temperature changes and/or heavy RF activity will cause this. We test temperatures from -40C to +85C.
If the device is reset RF calibration is done and characteristics are ok again.
This behavior is seen in the attached screen dumps from measurements. At -40C the
the instrument can't even recognize the signal/data rate.
Normal room temperature, good signal:
NINA-W131 #311 Wi-Fi Char 54Mbit 25C.png
Low temperature, bad signal:
NINA-W131 #311 Wi-Fi Char 54Mbit -40C.png
Low temperature after reset, good signal:
NINA-W131 #311 Wi-Fi Char 54Mbit -40C (after reset).png
For the test we use the test commands:
fcc_mode_sel 2
wifitxout 6 0xc 12 (channel 6, data rate 54Mbps, Attenuation 3dB)
Is there any way run the calibration periodically or automatically when temperature changes.
Can calibration be initiated from the application?
Best regards,
Ola
when testing RF tx characteristics at different temperatures we see that the output power and EVM values drift out of spec.
Ambient temperature changes and/or heavy RF activity will cause this. We test temperatures from -40C to +85C.
If the device is reset RF calibration is done and characteristics are ok again.
This behavior is seen in the attached screen dumps from measurements. At -40C the
the instrument can't even recognize the signal/data rate.
Normal room temperature, good signal:
NINA-W131 #311 Wi-Fi Char 54Mbit 25C.png
Low temperature, bad signal:
NINA-W131 #311 Wi-Fi Char 54Mbit -40C.png
Low temperature after reset, good signal:
NINA-W131 #311 Wi-Fi Char 54Mbit -40C (after reset).png
For the test we use the test commands:
fcc_mode_sel 2
wifitxout 6 0xc 12 (channel 6, data rate 54Mbps, Attenuation 3dB)
Is there any way run the calibration periodically or automatically when temperature changes.
Can calibration be initiated from the application?
Best regards,
Ola