mm Wave IWR - Sensor application for bullet ballistic measureing

Adriaan du Plessis

Other Parts Discussed in Thread: IWR1443BOOST, IWR1443

Good afternoon,

II'm looking at the mmWave IWR, to build a device to measure bullet ballistics over a distance. Speed and drop specifically. Is the mmWave IWR capable or is there a different product you could recommend.

Regards

over 8 years ago

0 Vaibhav Mahimkar over 8 years ago

TI__Mastermind 23725 points

Hello Adriaan,

It would be difficult to provide a clean yes or no answer here. We have not specifically tried it for such applications and would not have data to support it.
Just going by the high speed, long distance for a relatively small object it would be a difficult one for our standard out of box demo processing.

Having said that, there are processing algorithms that can detect speeds in excess of 120mph using mmWave devices and sense objects as thin as metal wires at a distance. So such an application would be worth a try with our EVM board.

IWR1443BOOST has IWR1443 device and antennas for Transmitter/Receivers on board and should enable such experiments.

Thank you,
Vaibhav

0 Nitin Sakhuja over 8 years ago in reply to Vaibhav Mahimkar

TI__Mastermind 30405 points

Hi Adriaan,

What is the maximum target velocity for your application? Assuming that typical muzzle velocities can range from 400 Kms/hr all the way up to a few thousand kms/hr (4000 km/hr), it may not be possible to natively measure such speeds as explained in the following post which talks about the basics of velocity measurement with mmWave Radar and the associated limitations.

e2e.ti.com/.../2251032

Basically, as given in the above post,

Vmax = Lambda / 4*Tc, where Lambda is the wavelength (4mm) and Tc is the chirp time. Which means the faster you can chirp, the higher the maximum velocity you can measure.

Assuming, at the lower end, a speed of 600Kmph, ( ~139 m/sec), the chirp time comes out to:

Tc = 0.004 / (4 * 138.88) i.e. 6 micro secs, which is too low.

As shown in the above diagram, Chirp Time, Tc = Idle time + Chirp time (ADC Start + ADC Sampling + Excess Ramp)

The minimum Idle time alone needed for ramp bandwidths less than 1Ghz is more than 2us. Similarly, other components of Tc i.e. ADC Start time, ADC sampling time and Excess Ramp time have constraints as documented in this app note which make it impractical to configure a chirp that short.

That being said, there are velocity extension algorithms that can be run in higher layer software (after detection) that can extend the measurable velocity by a few times the native speed measured by the sensor. You can enter your use case parameters (maximum distance, velocity, velocity resolution etc) in the mmWave Sensing Estimator to get an idea of the maximum native speed which you can achieve before velocity extension algorithms, based on your requirements.

Regards

-Nitin

0 Adriaan du Plessis over 8 years ago in reply to Nitin Sakhuja

Prodigy 20 points

Good morning,

Thank you for your feedback. The speed will be from 2500ft/s - 3500ft/s and up to a range of 50m. It does not look like I'll be able to effectively measure the speed with this product. Any suggestions on other ?

Regards

0 Nitin Sakhuja over 8 years ago in reply to Adriaan du Plessis

TI__Mastermind 30405 points

HI Adriaan,

I would suggest getting in touch with your local TI Sales office to find out about any other products that may be available for such extremely high velocity measurement applications. You can also post a new question on TI Forum and it should be directed to the appropriate sales/marketing teams which can help you discover any solutions TI may have in this arena.

May I request you to close this thread if your question has been answered from an mmWave perspective?

Thanks
-Nitin

Sensors

Sensors forum

mm Wave IWR - Sensor application for bullet ballistic measureing