AWR1642BOOST: mmWave Sensing Estimator : Negative values in "Chirp Configuration Parameters"

Hi Alper,

All the parameters negative might be an issue with Estimator, as you were doing some random selection. I would request you to select valid option to find out right configuration parameters.

And to find all these parameter you can refer

Frequency slope can be negative value. Frequency slop const is the value which needs to be set into API(AWR PROFILE CONF SB) which parameter device will convert based on LSB   (1LSB= 48.249KHz/s). freq slope const 1476  = 1476*48.249 = 71.26MHz/s

Thanks,

Jitendra

Hi Jitendra,

Thanks for advice and information.

However, there is a little confusion that I wish to resolve.

It is not that all the "Chirp Configuration Parameters" have negative values when I try some random scene parameters, rather, I get some (not all) of the "Chirp Configuration Parameters" with negative values.

You have already advised that Frequency Slope can have negative value, can you please advise how could that be possible?

In addition, please advise, for example, that can Frequency Slope Constant and Number of Samples / Chirp have negative values for a valid set of "Chirp Configuration Parameters" (provided that no error is shown in console window) ?

Thanks and regards

Hi Alper,

I would request you to go over ICD document which has all the parameter details or refer mmwavelink doxygen from SDK.

In the chirp config, all the parameters must be +ve, negative value is not permitted (ICD: Table 5.22).

Could you specify which parameter is getting -ve value in the chirp conf parameter?

Negative slope: In mmwave sensor available frequency sweeps are sawtooth and triangular. The type Sawtooth is a sweep of linearly increasing/decreasing frequency. When the highest frequency is reached, the sweep restarts at the lowest frequency. The type Triangular is a sweep of first linearly increasing frequency and then linearly decreasing frequency (together but little chirp idle time delay in b/w of chirp). This triangular will affect the velocity resolution. Further you can google of lot more usage of +ve/-ve slope of frequency ramp.

Please provide exact step to reproduce this negative chirp parameter from sensing estimator, it might be a bug in the tool which we need to fix. 

And further if you this -v parameters with the device, it will throw an error.

Regards,

Jitendra

Hi Jitendra,

Thank you again for your advice.

Well, I am aware of sawtooth and triangular waveforms and the concept of negative frequency slope which implies a decreasing frequency but thank you for the refresher.

My query was based on the following famous widely used TI figure.

From the above figure, I (possibly wrongly) assumed three things about the TI mmwave devices:

1)  TI mmwave devices can only generate sawtooth waveform chirps (with ONLY positive frequency slopes)

2)  TI mmwave devices cannot produce sawtooth waveform chirps with negative frequency slopes.

3)  TI mmwave devices cannot produce triangular waveform chirps having (possibly) equal  (or unequal) positive and negative frequency slopes.

In you message of 23rd August, you stated that frequency slope CAN have negative value,

This information is very important and rather eye-opening for me as it was contrary to my assumption based on above TI figure.

I am sure that certain other users might be having same supposition.

Therefore, I request you please explicitly negate or confirm the following statements:

1)   TI mmwave devices can produce sawtooth waveform chirps with negative frequency slope.

2)  TI mmwave devices can produce triangular waveforms with equal positive and negative frequency slopes.

3)  Can TI mmwave devices produce asymmetrical triangular i.e. waveforms with unequal positive and negative frequency slopes.

Apart from that, i will try to reproduce imaginary scene scenarios to obtain negative Chirp Configuration Parameters from mmwave Sensing estimator Tool and if I succeed, I will share those details with you .

Thank you.

Hi Jitendra,

Thank you very much for your valuable and elaborate reply.

Regards