Hi everyone,
I'm working on the vital sign project. In one of my test, I could get a single clean peak in the Range Profile plot, which should indicate a high SNR. But, strangely, I couldn't get good VitalWaveForms and Vital Sign Rate Estimation.
Later on, I found out that the problem is with the Rangebin_Index. The Rangbin_Index doesn't reflect the Actual Distance of the subject wrt the antenna while the Range Profile plot does. For a subject sitting at a distance 0.8 meters away, the Rangbin_Index should correspond to a value around 20. But the Rangbin_Index stays at 5 even after I refreshed the vitalSign_matlab GUI (Multiple times) and have the subject varied his radio distance wrt the antenna. On the other hand, the Range Profile plot did consistently show a very good estimation of the range and reflected the changes in the subject’s distance.
So, I'm thinking the reason I couldn't get the waveforms plotted right even with a very clean peak in the Range Profile window is that the Program is extracting the phase information from the Wrong Range Bin.
Does this mean the range FFT isn't working properly? Also, is there any correlation between the Rangebin_Index and the Range Profile plot? As far as my observation goes, they are not related at all.
Also, in another test, where I could get good vital waveforms and rate estimations, I still get some intermittent flat-line in both ChestMovement_wfm and BR_wfm. And the problem is still with the Rangebin_Index. Every time the Rangebin_Index changes to 5, the extraction of phase information fails, which makes sense.
But I don’t understand what is causing the Rangebin_Index calculation failure, and why the value of the Rangebin_Index consistently falls back to 5 when the rang bin calculation is incorrect?
Thank you so much,
Zhengguo Sun