IWR6843: txPhaseShifter parameter issue

Agate

Part Number: IWR6843

Dear TI

This is from your ti\mmwave_industrial_toolbox_4_2_0__win\mmwave_industrial_toolbox_4_2_0\labs\long_range_people_detection\68xx_long_range_people_det\docs

Beamforming_in_LRPD Page 4

All 3 TX is enabled at the same time. These four subframes are aim to focus on the angle of [-15, 0, 15, 30].
profileCfg 0 61.0 10 6 135 0 8174592 1.8 1 256 2000 0 0 48
profileCfg 1 61.0 10 6 135 0 0 1.8 1 256 2000 0 0 48
profileCfg 2 61.0 10 6 135 0 8668160 1.8 1 256 2000 0 0 48
profileCfg 3 61.0 10 6 135 0 16809984 1.8 1 256 2000 0 0 48

And Page 2

brief Concatenated phase shift for TX0/1/2, b1:0 reserved (set to 0b00); b7:2 TX0 phase shift value 1 LSB = 360/2^6 = 5.625 degrees b9:8 reserved (set to 0b00); b15:10 TX1 phase shift value 1 LSB = 360/2^6 = 5.625 degrees b17:16 reserved (set to 0b00); b23:18 TX2 phase shift value 1 LSB = 360/2^6 = 5.625 degrees b31:24 Reserved This field defines the additional phase shift to be introduced on each transmitter output. In IWR6843 ES1.0, only 0 degree phase is supported.

angle -15 = 8174592 ???

angle +15 = 8668160 ???

angle +39 = 16809984 ???

angle +12 = ?

1. Our questiion is your description can't match between page 2 & 4 .

2. How to setting the "txPhaseShifter" parameter ? Can description detail with diagram and provide tool for txPhaseShifter parameter ?

3. Why not provide gui tool for radar configuration ? Parameter scale could confusing user .

4. If have TX beamforming tuning guide could share for users ?

Best Regards

Jasper

over 5 years ago

0 Justin Curewitz over 5 years ago

TI__Mastermind 28055 points

Hi Jasper,

1. After writing the document, we adjusted the configuration to cover the following angles:

-33.75

-11.25

11.25

33.75

This is why the chirp config does not match the document example.

2. The document explains how to set the parameter. Section 2 details the phase shift calcuation, and section 3 details how to convert this to the value in the profile Config.

3. You can use the following matlab script to calculate the phase shift value:

--------------------------------------------------------------------------------------------------

theta_desired = -33.75;

m_ind = [0 1 2]; % antenna distance in unit of lambda

phaseInc = 5.625; % step size for the phase shifter

phaseTX_rad = 2*pi*(m_ind*sind(theta_desired));

phaseTX_deg = (phaseTX_rad)*180/pi;

phaseTX_deg_wrap = wrapTo360(phaseTX_deg);

phaseShifter = round(phaseTX_deg_wrap/phaseInc) * [ 0, 2^8, 2^16].' * 4

----------------------------------------------------------------------------------------------------

4. What would you want to see in a Tx Beamforming tuning guide?

Regards,
Justin

0 Agate over 5 years ago in reply to Justin Curewitz

Expert 1275 points

Dear Justin

The below value are OK ? your description is very detail but we are use TI mmwave chip for product design not for university.study.

( Parameters are very much and no direct value look up table for tuning our design become very slow.)

we need direct look up table for application , can release look up table or guide for users ?

1. Look up table vs formula : which one is better for system performance tuning ?

2. We lack of matlab tool for this .

degree vs configuration

-33.75 = 8174592

-11.25 = 0

11.25 = 8668160

33.75 = 16809984

In the following example, we create 4 subframes. All 3 TX is enabled at the same time. These four subframes are aim to focus on the angle of [-15, 0, 15, 30].
profileCfg 0 61.0 10 6 135 0 8174592 1.8 1 256 2000 0 0 48
profileCfg 1 61.0 10 6 135 0 0 1.8 1 256 2000 0 0 48
profileCfg 2 61.0 10 6 135 0 8668160 1.8 1 256 2000 0 0 48
profileCfg 3 61.0 10 6 135 0 16809984 1.8 1 256 2000 0 0 48

Best Regards

Jasper

0 Justin Curewitz over 5 years ago in reply to Agate

TI__Mastermind 28055 points

Hi Jasper,

In the document, Beamforming_in_LRPD.pdf, we use the angles [-15, 0, 15, 30]. However, in the chirp configuration, we used [-33.75, -11.25, 11.25, 33.75]

You can try this python script which is functionally equivalent to the matlab script:

------------------------------------------------------------------------------------------------------------

import math as m

thetas = [-33.75, -11.25, 11.25, 33.75]

for theta_desired in thetas:

m_ind = [0, 1, 2] # antenna distance in unit of lambda

phaseInc = 5.625 # step size for the phase shifter

phaseTx_rad = [0, 0, 0]

phaseTX_deg = [0, 0, 0]

phaseTX_deg_wrap = [0, 0, 0]

for i in range(3):

phaseTx_rad[i] = 2*m.pi*(m_ind[i]*m.sin(m.radians(theta_desired)))

phaseTX_deg[i] = m.degrees(phaseTx_rad[i])

phaseTX_deg_wrap[i] = round((phaseTX_deg[i]%360)/phaseInc)

#get sdk value

phaseShifter = 0

offset = [ m.pow(2,0), m.pow(2,8), m.pow(2,16)]

for i in range(3):

phaseShifter += phaseTX_deg_wrap[i]*offset[i]

print(phaseShifter*4)

-----------------------------------------------------------------------------------------------------------

It will return the values in the chirp configuration in the industrial toolbox, which are:

14970880.0
10276864.0
6565888.0
1871872.0

This will allow you to quickly try a different set of angles. Just replace the angles in the list "thetas" with the angles you want to beamsteer towards.

Regards,

Justin

0 Agate over 5 years ago in reply to Justin Curewitz

Expert 1275 points

Dear Justin

Thank your fully support .

Best Regards

Jasper

0 Agate over 5 years ago in reply to Agate

Expert 1275 points

Dear Jutin

try your code as below , result some different .

0.0
36864.0
1871872.0

Process finished with exit code 0

0 Justin Curewitz over 5 years ago in reply to Agate

TI__Mastermind 28055 points

Hi Jasper,

Please check that you are using the same array thetas as I am. Please ensure that indentation is correct in your script.

Regards,

Justin

Fullscreen phaseShift.txt Download

import math as m
#thetas = [-33.75, -11.25, 11.25, 33.75]
thetas = [-15, 0, 15, 30]
for theta_desired in thetas:

	m_ind = [0, 1, 2]   # antenna distance in unit of lambda  

	phaseInc = 5.625 # step size for the phase shifter

	phaseTx_rad = [0, 0, 0]
	phaseTX_deg = [0, 0, 0]
	phaseTX_deg_wrap = [0, 0, 0]
	for i in range(3):
		phaseTx_rad[i] = 2*m.pi*(m_ind[i]*m.sin(m.radians(theta_desired)))
		phaseTX_deg[i] = m.degrees(phaseTx_rad[i])
		phaseTX_deg_wrap[i] = round((phaseTX_deg[i]%360)/phaseInc)
	#get sdk value
	phaseShifter = 0
	offset = [ m.pow(2,0), m.pow(2,8), m.pow(2,16)]
	for i in range(3):
		phaseShifter += phaseTX_deg_wrap[i]*offset[i]
	print(phaseShifter*4)

0 Agate over 5 years ago in reply to Justin Curewitz

Expert 1275 points

Dear Justin

Check OK (Step by Step) . Thank a lot .

Best Regards

Jasper

Sensors

Sensors forum

IWR6843: txPhaseShifter parameter issue