Hi,
I have a few questions concerning the recovery of raw data from the mmwave demo visualizer. I have notice a number of other people with similar interests. I have both looked at both the reference index.html file and the source code in the visualizer gui. I have also tried to locate the capture_demo.m file for additional guidance but can not find it in either the linux or windows sdk version. It was suggested to someone to reinstall it but that does not help. It is just not available in the current versions.
I have parsed the raw data created by the mmwave demo visualizer using
the iwr1443 senor chip. The data from the range and statistic tags
appear to be the same as presented in the Demo Visualizer but I have a
few questions concerning the data from the detectedObj tag.
1. On page 10 of the user manual (swru529a.pdf), the threshold scale
has three formats, i.e., linear, dB and CLI. I am confused why the
need for three scales and I am slightly confused by what CLI is. Can
you please explain?
2. It appears that the magnitude levels provided in range tag has a
linear scale. Is this correct? I assume that the plotted magnitudes
in the Demo Visualizer is 10log(linear) but from the reference in
Question 1, 20log_10 is used and I see that the code for peakVal uses
10log_10 (peakval.gif). Can you provide some clarification? It has been verified in the forum that is is 10ln(linear).
3. Questions pertaining to the detected object tag. Examples of a measurement for a stationary target
are shown below for the following questions.
range dopplerIdx peakVal x y z sqrt(x*x+y*y)
4.08816971E-02 0 1239 -3.90625000E-02 9.76562500E-03 0.00000000 4.02647033E-02
1.83967650 0 17534 -0.115234375 1.83789062 0.00000000 1.84149969
4.08816971E-02 0 1205 2.73437500E-02 2.92968750E-02 0.00000000 4.00747731E-02
Don't know why the third line repeats the same range value but the other values are different. The display range plot in the gui is shown in image2.gif and it only displays to detected objects. Please advise.
a. The range provided by the rangeIdx parameter and the x, y, z
values (sqrt(x*x+y*y+z*z)) are very close but not the same. Is this
due to some rounding off error? For the data in the above listing, the target was stationary. When it is moving, the spread between the range column and sqrt column is larger.
b. The peakVal number for each object does not seem to correspond to
the peak values of the range tag information. Are the peakVal
numbers in a linear scale as the range tag data? The range tag data in the vicinity of the two large returns are
Range Amplitude
4.08816971E-02 9656
8.17633942E-02 10184
0.122645088 10072
0.163526788 9824
....
1.71703124 9032
1.75791299 9144
1.79879463 10440
1.83967638 11664
1.88055801 11856
1.92143977 11848
1.96232140 11376
2.00320315 9856
Different values than the detected object data.
c. I am having difficulties reproducing the velocities that the gui
is producing. The image conversion.gif illustrates what the code is
using. My measurement object is a corner reflecting moving on a
track at a known fixed rate. I observe the velocity value generated
by the gui and I can not generate this value. My code is shown in
code.gif and is functionally the same as in conversion.gif. My
velocity values appear to have a resolution of 1 mps when scaled but
your velocity resolution equation indicates that the resolution
should be much finer. Thoughts?
d. Image range.gif shows my recoverd data for detectedObj data and
the range data. The range data agrees with the generated curve in
the Demo Visualizer. The red stars are from the detectedObj tag.
There appear to be many objects at essentially the same distance but
with different magnitudes. I would not have expected so many
detected objects at the same location and the magnitudes are all
over the place. Your thoughts?
4. The expression provided in
mmwave_sdk_02_00_00_04/packages/ti/demo/xwr16xx/mmw/docs/doxygen/html/index.html
for velocity given dopplerIdx must be a mistake. I would say that
this expression yields the velocity resolution and not the velocity as
suggested in conversion.gif. Is this correct? Please see
conversion.gif and index.gif.
Thanks.
Al