MMWCAS-RF-EVM: calculation of frame length

brickporter

Intellectual 335 points

Part Number: MMWCAS-RF-EVM

Hi Ti specialists:

The frame length of MRR mode in Table 2 of Design guide — TIDEP-01012 makes me confused.

To my understanding, the frame length is calculated as

FrameTime = (RampEndTime + IdleTime) x (NumOfChirps per frame per Tx) x NumTx. (Eq, A)

Using the chirp configuration and there are 9 Tx antennae used in MRR mode, we can obtain frame length as

(23 + 4)us x 128 x 9 ~ 31.1ms.

However, Table 2 shows the frame length of MRR mode is 4.4ms. Do I miss something?

Regards,

Stan

over 3 years ago

0 Abhed Misra over 3 years ago

TI__Genius 13805 points

Hi,

Please refer thsi thread and do let me know in case you still have doubts.

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1039484/awr2243-the-doubt-about-the-document-zhcu682a-imaging-radar-using-cascaded-mmwave-sensor-01012

Regards

0 brickporter over 3 years ago in reply to Abhed Misra

Intellectual 335 points

Hi Abhed:

The question in the thread is different from mine.

In the thread, the author would like to know why 3.456ms (=128*27us) does not match 4.4 ms indicated in the Table.

On the other hand, I am confused about why 31.1ms does not match 4.4 ms.

Regards,

Stan

0 Abhed Misra over 3 years ago in reply to brickporter

TI__Genius 13805 points

Hi,

let me check on MRR configuration also.

Regards

+1 Abhed Misra over 3 years ago in reply to Abhed Misra

TI__Genius 13805 points

Hi,

Thanks for your patience and query.

This indeed seems to be a typo. Your understanding of the Frame length calculation is correct.

FrameTime = (RampEndTime + IdleTime) x (NumOfChirps per frame per Tx) x NumTx

And it Matches for SRR

SRR = (40 +5) * 128 * 12 = 69.12msec

however doesn’t match the MRR.

MRR =(23 + 4) * 128 * 12 = 43msec instead of 4.4msec.

Will have this raised as update in the document.

Regards

0 brickporter over 3 years ago in reply to Abhed Misra

Intellectual 335 points

Hi Abhed:

Thanks for reply. It's clear to me.

An point is that the number of Tx is should be set as 9 according Design guide — TIDEP-01012 .

Please refer

In your calculation, the number of Tx is set as 12.

Regards,

Stan

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MMWCAS-RF-EVM: calculation of frame length