AWR1642: Difference between profileCfg and real wave form

Kei

Intellectual 750 points

Part Number: AWR1642

Hello, TI team,

I have a question about profileCfg for AWR1642.

I set profileCfg as follows:
profileCfg 0 76.1 7 7 18.24 771 0 10 1 64 6250 0 0 48

This means Idle Time is 7us, Ramp End Time is 18.24us, and txStartTime is 1us.

Then I tried observing the shape of the chirp output from AWR1642 by using oscilloscope with FMCW signal analyzing software,
and the result is follows.

From the result, it looks like Ramp End Time is 16.9us, and Idle Time is 8.3us.

(But Chirp Cycle Time is OK. Because 7us + 18.24us is 25.24us and observed time was about 25.3us)

Do you have any ideas why there is difference between profileCfg and real wave form?

I used xwr16xx_mmw_demo.bin in SDK2.1.

Regards,

over 4 years ago

0 Kyle Cousino over 4 years ago

TI__Mastermind 24955 points

0 Kyle Cousino over 4 years ago in reply to Kyle Cousino

TI__Mastermind 24955 points

Here is the chirp diagram reference from the SDK documentation.

In your profile, the tx start time is 1 us. Which means this subtracts from the ramp end time. In your case, you specify the ramp end time to be 18.24 us. But since the tx start time is 1 us, the real chirping takes place for 17.24 us. This is also why it looks like your idle time is 8 us instead of 7 us.

The TX start time value can take on both positive and negative values. You can refer to the SDK Doxygen for more detailed information.

The piece of information to keep in mind is that the total time for each chirp is defined as the sum of the idle time and ramp end time.

Regards,

Kyle

0 Kei over 4 years ago in reply to Kyle Cousino

Intellectual 750 points

Hi,

Thank you for your reply. I understand very well.

Now, I set profileCfg as follows:
profileCfg 0 76.1 7 7 18.24 771 0 10 -4 64 6250 0 0 48

This means txStartTime is -4us, but the wave form below was observed.

Observed frequency constant time is about 2.3us, and ramp end time is about 19.7us.

I suppose frequency constant time will be 4us, and ramp end time will be 18.24us.

Why does the chirp look like the observed wave form?

Regards,

0 Kyle Cousino over 4 years ago in reply to Kei

TI__Mastermind 24955 points

It looks like you have indicated that my initial response helped to resolve your issue. If you have any additional questions related to this specific thread, please respond. Otherwise, this thread will be considered resolved and closed.

Regards,

Kyle