RangResolution setting to 37.5mm

Kentarou Kobayashi

Other Parts Discussed in Thread: IWR6843

Thank you for all your support

I test the resolving power of the radar using mmWave module.
It is understood that the resolving power of the radar is decided in BandWidh.
The setting of BandWidth understands the thing by the setting of FrequencySlope and RampEndTimen.

Therefore I changed RampEndTime and input (40μsec ← 60μsec) In BandWidh of Sensor Config,
"1798.92MHz ⇒ 1199.28MHz" and indication were changed (Frequency Slope is 29.982MHz/μsec),
Though it is shown 40μsec and a change Ramp EndTime in Programmed Parameters when
I confirm the measurement log in PostProc, in Calculated Parameters, 0.7675GHz, RangResolution are not changed with 0.1953m BandWidth.

Please tell me the setting you want to drive RangResolution to 37.5mm (BandWidth is 4GHz).

over 3 years ago

0 Cesar over 3 years ago

TI__Guru*** 147964 points

Hi,

Please note that 37.5mm is a theoretical range resolution. In practice the number should be a little higher

Please see this FAQ that shows how to compute range resolution

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1050220/faq-computing-maximum-range-velocity-and-resolution-mmwave-system

Thank you

Cesar

0 Kentarou Kobayashi over 3 years ago in reply to Cesar

Prodigy 80 points

Thank you for providing this Cesar.

This agenda is IWR11××. Then how about A at time of IWR6843? (fc=60GHz)

Do 『profileCfg』,『chirpCfg 』and 『frameCfg』 input from senser config screen from 『Manage profile』?

0 Cesar over 3 years ago in reply to Kentarou Kobayashi

TI__Guru*** 147964 points

Hi,

I am sorry I don't understand the question.

For IWR6843 (60GHz) the behavior is similar

What is important is the bandwidth not the starting frequency

thank you

Cesar

0 zigang Yang over 3 years ago

TI__Mastermind 39835 points

HI,

Regarding your first question: why you increase the ramp time, and the range resolution did not change.

The ramp time is separate into ADC start time + valid ADC sampling time + excess time. Increasing the ramp time only results in high excess time, which is not contribute to the valid bandwidth. In order to increase the valid bandwidth (= valid ADC sampling time * freqSlope = numAdcSample/adcRate * freqSlope), you can

1) Slow down the ADC sampling rate to increase the ADC sampling time.

2) Increase the frequency slope.

Please refer to following app notes for details. https://www.ti.com/lit/an/swra553a/swra553a.pdf

And since 4G is the total available sweep bandwidth, and the valid sweep bandwidth is smaller due to the minimum requirement on ADC start time and excess time. Therefore, you will not be able to achieve the range resolution 37.5mm.

Best,

Zigang

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RangResolution setting to 37.5mm