Hi,
My customer tried to get the min chirp period based on the recommend parameter from Ramp Timing Calculator in Radar studio. But they found the recommend idle time and ADC start time from Ramp Timing Calculator is too small sometimes and the ADC data has unexpected overshoot at the first several bins. They need to try several times to get the right idle time and ADC start time.
Why the recommend idle time and ADC start time from Ramp Timing Calculator is too small sometimes? Is there any other way or suggestion for customer to get the min workable idle time/ADC start time more easier, not just try again and again?
Below are tests which can reproduce customer's problem. All tests are based on xWR1443 EVM (ES2.0) , capture demo in mmWave SDK 1.0 and radar studio 1.7.4.0.From below snapshot, you will find the recommend idle time/ADC start time for Slop=10Mhz/us, ADC Samples=256, sample rate =10Msps is 2us/3.78us.
The left figures in below shows the abs of the complex first chirp ADC sample data.
frame = rad_in(1:K,1) + i*rad_in(1:K,2);
abs_radar=abs(frame);
The right figures in below shows the real part of the complex first chirp ADC sample data. The ADC data is saved from L3 (start address 0x51020000). I uses the idle time =2us and ADC start time =4us and you can see overshoot in both figures.
flushCfg
dfeDataOutputMode 1
channelCfg 2 1 0
adcCfg 2 1
adcbufCfg 0 0 1 1
lowPower 0 0
profileCfg 0 77 2 4 31 0 0 10 1 256 10000 0 0 48
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 1
frameCfg 0 1 128 1 50 1 0
sensorStart
Then I increased the idle time/ADC time by 1us. I still see the overshoot.
flushCfg
dfeDataOutputMode 1
channelCfg 2 1 0
adcCfg 2 1
adcbufCfg 0 0 1 1
lowPower 0 0
profileCfg 0 77 3 5 31 0 0 10 1 256 10000 0 0 48
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 1
frameCfg 0 1 128 1 50 1 0
sensorStart
Then I increased again. Now I think the ADC data is normal.
flushCfg
dfeDataOutputMode 1
channelCfg 2 1 0
adcCfg 2 1
adcbufCfg 0 0 1 1
lowPower 0 0
profileCfg 0 77 4 6 35 0 0 10 1 256 10000 0 0 48
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 1
frameCfg 0 1 128 1 50 1 0
sensorStart
Thanks,