[Rx Gain-Phase Monitor] Detecting faulty Rx loopback tone's power level via error-code 291.

Which Loopback mode are you using for your testing?

-E. Shareef

Loopback chirps aren't used for this testing, instead, the loopback signal that is internal generated as part of the Rx Gain-Phase monitoring (AWR_MONITOR_RX_GAIN_PHASE_CONF_SB) is the one of interest.

Posting the snapshot of the Rx loopback internal architecture, for reference :

And to restate my request, I'm interested in injecting a faulty loopback signal that gets detected by the QPSK PD and gets reported to the host software via the error-code 291.

Thanks,

Workiing on your request. Please allow some time for a response. 

Thanks.

E. Shareef

Hello,

You can try applying higher tx BO to reduce the power at the PD.

-E. Shareef

Hi Shareef,

As far as I understand, the Tx PAs are turned off during the execution of Rx Gain-Phase monitor, so the Tx BO is irrelevant in this usecase.

Also, in my tests, I'm already using a Tx BO setting of 10dB, however this setting is primarily aimed at reducing emissions of Type1/Type2 monitors.

Trilok

Hello Trilok,

Thank you for the info on BO. Let me try to recreate this on our end and get back to you. 

Hi Trilok, 

Please refer to the Interface Control Document section 8.18 (Analog Fault injection). You can enable fault injection for the particular TX chain during monitor test which will result in TX power dropping below -40dBm. 

Regards,

Aydin 

Hi Aydin,

I'm assuming that you are referring to "TX Gain Drop" field of the Analog fault injection.

If yes, then I believe this will not serve the purpose, since the Tx gain/power drop is achieved via the TX PAs and this chain isn't involved in the RX Gain-Phase monitoring loopback path as shown in the below picture : 

In any case, I tried to inject the TX gain drop error via the Analog fault injection API and I didn't see any noticable difference in the loopback power measured via RX Gain-Phase monitoring.

Please confirm the suggestions in your setup and let me know the method which actually works on your setup.

Trilok

Are you checking the LOOPBACK_POWER or the RX_GAIN_VALUE? both results come out of the loopback monitor (AWR_MONITOR_RX_GAIN_PHASE_REPORT_AE_SB) but TX power drop should be seen in the LOOPBACK_POWER.

Regards,

Aydin 

I'm checking the LOOPBACK_POWER and it remains at around -38dBm even after TX_GAIN_DROP fault injection.

Trilok

Hi Trilok

From Self-Calibration of mmWave Radar Devices (Rev. C), it said that

"Other calibrations, such as Rx gain calibration, use internal RF loop structures to feed a known amplitude of signal level from the TX chain to the Rx chain. The Rx gain is analyzed by processing the ADC data amplitude and accordingly the Rx chain biases are set to calibrate the gain."

The signal level is of known amplitude, I am afraid it means fixed pattern and there is no interface to adjust this signal.

Thanks

Ken

Hi Ken,

Thanks for confirming the design/behavior.

I would appreciate if future questions are answered quicker and without relying on customers to "trying out" the potential methods.

Trilok