WEBENCH® Tools/AWR1443: Initial phase problem

miaom

Prodigy 25 points

Part Number: AWR1443

Tool/software: WEBENCH® Design Tools

In the “mmwaveSensing-FMCW-offlineviewing_2”，presented

From this picture, we can found IF frequency and phase chage, but what is the initial phase?

Is 2*pi*fc*(2d/c)? or what?

over 5 years ago

0 Cesar over 5 years ago

TI__Guru*** 149204 points

We will check with the author of the training and will get back to you

thank you
Cesar

0 Sandeep Rao30 over 5 years ago in reply to Cesar

TI__Prodigy 565 points

Yes 2*pi*fc*(2d/c) is right.

0 miaom over 5 years ago in reply to Sandeep Rao30

Prodigy 25 points

Thank you

However, the initial value of phase change at a distance d after 1d-fft is not equal to 2*pi*fc*(2d/c). why? What other factors will affect this initial value?

0 Sandeep Rao30 over 5 years ago in reply to miaom

TI__Prodigy 565 points

In practice there are many factors which effect the initial phase. These include : group delay in the device front end, routing delay of the signals on the board (between device and antenna). All of these factors effect the round trip delay and hence the initial value of the phase. [Note that the phase is very sensitive to round trip delay - an additional distance of 1mm => 180 degree phase change.].

However, note that the initial phase offset does not effect effect range-FFT, Doppler-FFT or angle-FFT. For e.g., Doppler-FFT relies on change in phase across chirps and not the absolute phase value.

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WEBENCH® Tools/AWR1443: Initial phase problem