IWR1642: LPF failed

Hello,

By LPF do you mean Low Pass Filter? Which demo binary are you testing/starting from?

Thanks,

Jackson

Yes,:LPF means Low Pass Filter.

We used lab0002_short_range_radar,USRR mode.

Hi,

I don't think this is related to the LPF.

It could be related to the layout of the board and power management.

We have seen in the past ghost images produced by the power management on the board.

thank  you

Cesar

Sorry, I didn't say clear in detail before, I judge this target is caused by the overrange from the following phenomena.

1.The azimuth of the ghost target changes steadily and regularly as the radar rotates..ghost targets due to power management problems do not have this phenomenon.

2.The distance of the ghost target steadily varies with the distance of the obstacle, and if the obstacle comes within radar range, the ghost target disappears

From the above phenomena, I judge that this is not a real ghost target, but a real target due to the miscalculation of distance,Therefore, I infer that the LPF of the radar failed due to some factors.

Thank you for additional details

So, the hypothesis is that this would be a problem for that specific chip.

First, do you have a second board with same PCB that works?

I have not heard about problems with LPF before. I need to check with extended team

thank you

Cesar

Hi,all PCBs with this PCB layout have this problem.Our other PCBs with another PCB layout did not have this problem.  

We wanted to know if there were possible interference paths that could affect the performance of the LPF.  

Sorry for the delay

We don't think this is related to the LPF, but might be some thing to do with the image signal leaking into the desired band.

Can you provide the following information?

1. Is complex 1x mode used or complex 2x?
2. Could you provide the details of the sampling rate used , what is the intended IF frequency of the object and what is the IF frequency of the observed “ghost” object seen?It seems that you have done the experiment with different distances of the object, if you could tabulate all the results it would be helpful.
3. What is the signal level received in the RX for the two PCB designs? If you could tell the dBFS level of the object as seen in the ADC data for both the PCB designs that would help. The comparison needs to be done with the object at the same distance in both cases.

 Thank you

Cesar

Our application is based on lab0002_short_range_radar,USRR mode.so

1.It is ADC_FORMAT_COMPLEX.

2.The sampling rate is 6.222MHZ.

We are currently looking at the target data (range, Angle, speed) from the radar output, we are not looking at the spectrum data and raw ADC data.

I'm going to try to get the above data, We didn't reserve the UART interface from the original DEMO.

can you explain more about the image signal leaking?Is it mainly influenced by software or hardware?

The leakage is 100% hardware

thank you

Cesar

Thank you, Cesar,Is there any data information about image signal leakage?

Hi

Sorry for the delay

Image leakage is related to the digital baseband in the chip.

Do you see this problem is you reduce the sampling frequency?

Thank you

Cesar