IWR1642BOOST: Moving target mixed with the zero-Doppler bin (range profile) after BPM decoding

It looks like you only have one chirp config set up. You will need two for the BPM to work properly. See the below example of a script setting up 2 chirps for BPM config.

desired_interchirp_time_tr = 76
desired_idle_time_tx2 = 7;
ramp_end_time = 31  -- for 64 samples, will be adjusted for 48 samples
idle_times = {desired_interchirp_time_tr-(desired_idle_time_tx2+ramp_end_time)-ramp_end_time, desired_idle_time_tx2}

if(0 == ar1.ProfileConfig(0, 61.00, idle_times[1], 8, ramp_end_time, 22, 22, 22, 0, 0, 0, 99.000, 1, 64, 3000, 0, 0, 36)) then
                WriteToLog("ProfileConfig Success\n", "green")
else
                WriteToLog("ProfileConfig failure\n", "red")
end

if(0 == ar1.ProfileConfig(1, 61.00, idle_times[2], 8, ramp_end_time, 22, 22, 22, 0, 180, 0, 99.000, 1, 64, 3000, 0, 0, 36)) then
                WriteToLog("ProfileConfig Success\n", "green")
else
                WriteToLog("ProfileConfig failure\n", "red")
end

-- Chirp Config
-- ChirpConfig(chirpStartIndex, chirpEndIndex, profileId, startFrequencyVariation, frequencySlopeVariation, idleTimeVariation, adcStartVariation, antennaEnableMask)
if (0 == ar1.ChirpConfig(0, 0, 0, 0, 0, 0, 0, 1, 1, 0)) then
    WriteToLog("ChirpConfig Success\n", "green")
else
    WriteToLog("ChirpConfig failure\n", "red")
end

if (0 == ar1.ChirpConfig(1, 1, 1, 0, 0, 0, 0, 1, 1, 0)) then
    WriteToLog("ChirpConfig Success\n", "green")
else
    WriteToLog("ChirpConfig failure\n", "red")
end

Hopefully that helps. I am not sure about the demodulation scheme, as it is not really code, but your equation seems correct (assuming you meant Tx1 and Tx2 in the equation).

Also, for (2), since there are 2 TX antennas being used, the BPM scheme should increase SNR by about 10*log10(2) which is about 3dB.

Regards,

Jackson

Hi Jackson, 

Thank you very much for the help! I was referring this file (attached) for BPM raw ADC data capture. 

C:\ti\mmwave_sdk_03_05_00_04\packages\ti\demo\xwr16xx\mmw\profiles\profile_2d_bpm.cfg

It was using only one profile for two chirps. 

In my configuration (I was using IWR1642Boost), I used 

ar1.ChirpConfig(0, 1, 0, 0, 0, 0, 0, 1, 1, 0) which I thought it is equivalent to 

ar1.ChirpConfig(0, 0, 0, 0, 0, 0, 0, 1, 1, 0) and ar1.ChirpConfig(1, 1, 0, 0, 0, 0, 0, 1, 1, 0)

From your example, it uses two profiles for two chirps if I understand it correctly. 

For BPM configuration, does it requires two profiles?

Please give me 1~2 days for studying your example and testing.

Thanks, again!

Best,

Hang

5078.profile_2d_bpm.cfg

Hi Jackson,

May I have a quick question on ar1.BpmConfig()?

For my configuration for the 1st chirp both Tx1 and Tx2 has phase 0, for the 2nd chirp, Tx1 has phase 0 and Tx2 has phase 180.

Here are my configurations.

Does it look correct to you?

Thanks!

Best,

Hang

Hello,

Yes I think that looks correct. You are correct above, you do not need two chirp profiles, the example just happened to use them. But you do need two chirp configurations to switch the phase of TX2 in the second config. The BPMconfg will only control the demodulation, not the TX output, so you need these to match.

Regards,

Jackson