Radar sensor Forum Discussions

[trung]

Hi,

I 'm  using SPI mode  to  configure the  parameters for  the  radar  sensor .

I  am  configuring the  following :

FREQUENCY_61_1HZ_VALUE = 0xF72,

PULSE_WIDTH_5MICRO_S = 0x00,

DUTY_CYCLE_REPETITION_250MICRO_S = 0x00,

TX_POWER_DBM_4_5 = 0x07,

PGA_10_DB = 0x00,

HOLD_TIME_1S = 0x08,

SENSITIVITY_1 = 0x0780,

Everything worked steadily until I configured the sensitivity to pass level 8

Although  there  are no  detected objects in  the  detection area , TDet pin are constantly  fluctuating at  the  detection level  and  are not  detected.

Is it  interference? , do  you  have  a  solution  to  this  problem?

[GeorgeT]

Hi @trung,

I believe you are referring to BGT60LTR11AIP.

Could you please let me know whether "pass level 8" refers to sensitivity_8?

If that is the case, the sensitivity is very high at sensitivity_8. The radar can detect movement at farther points compared to the performance at sensitivity_1. The testing should be done more carefully at this level. After setting the threshold you can try approaching from a farther point and please avoid all the other movements in the radar range.

Please let me know whether the suggestion helped in getting the issue solved.

Thanks and regards,

George

[trung]

Hi @GeorgeT 

Thanks for your answer!

I  tried with  a  sensitivity  of  8,9,10,11,12,13,14. TDet signal  pin  jumps between  2 levels 0-1 when  there  is no  object  in  the  zone 

This my config Pulsed Mode for register of BGT60LTR11AIP with spi communication

Did I  write  the  value  to  the  register  of  the  radar  like  that ? Is there  a  problem  with  it?

[GeorgeT]

Hi @trung,

I tried configuring the BGT60LTRAIP mmic via SPI with the settings shared and is working fine.  So there is no issue with the register configuration. So the issue could be with the measurement environment.

At this level of sensitivity (0x0050) radar will detect very fine movements at a distance more than 6 m. Hence in the measurement setup please ensure there is no unwanted movements in this range.

I would suggest to start with sensitivity_4 (0x0280), which is already working, for which the range is less. Increase the sensitivity levels in steps keeping in mind that detection range also increases. Avoid unwanted movements in the radar range so that radar can detect the actual movement.

One other suggestion is to set the Register 15 to 0x4000 instead of 0x4020, while setting for the second time. It will just make the TDet active low.

Please let me know the results.

Thanks and regards,

George

[trung]

Hi @GeorgeT 

Thanks for Your answer!

Can  you  give  me  suggestions for  configuring Radar 's  registers.

Detection range : 5m, 3m, 2m. 

Ceiling mounting location.

Capable of detecting small movements.

Example: 

• The one who sits and reads the book
• People who work with laptops

[GeorgeT]

Hi @trung ,

You could use table 5 (page no: 7) in User's guide to BGT60LTR11AIP as reference for setting the threshold register (Register-2) for required radar range. 

As mentioned in the document each entry has 0.5 m range more than the previous value. For example, the value of 0x0380 (896) can be chosen for a range of 2 m and a value of 0x00C0 (192) for range of 5 m. Please note that these are not exact values, but can be used as reference. Some tuning is required for achieving the required range. 

Thanks and regards,

George

[trung]

Hi @GeorgeT 

Thanks for your answer!

What is Baseband PGA gain?

When I configurate PGA down level from 10 ->35 DB with Sensitivity 8 ->15.

No  interference  occurs when  reading  signals from  Tdet pins.

When I tried to configure PGA: 40-45-50 DB with Sensitivity of 8- 14, The  signal  read form Tdet is constantly  being  changed when  there  is no  object  in  the  zone.

Could the cause the circuit design by me is not responsive to high power when PGA with level 40-45-50?

[GeorgeT]

Hi @trung,

Happy to know that the radar is responding properly.

PGA refers to Programmable Gain Amplifier, which amplifies the received signal.

A higher gain can cause false detection which may be happening in your case.

Thanks and regards,

George

[trung]

Hi @GeorgeT 

Thanks for your answer!

These  are parameters that  affect  the  object  detection distance .

• PLL frequency word
• Medium power amplifier gain control
• Baseband PGA gain setting
• Sensitivity

So  what  parameters should  I  adjust  to  reduce  the  object  detection distance  so  that  the  Radar  works  well  with  high  sensitivity  and  stability?

[GeorgeT · Accepted solution]

Hi @trung,

Please note that there is no need to make changes to PLL frequency word and Medium power gain amplifier gain control.

As already suggested you can set the sensitivity/threshold for the required range and set the Baseband PGA gain at the maximum possible value such that there are no false detections.  Set at the maximum value of gain and try reducing the gain to achieve a level where there are no false detections.  In the given application as already mentioned, PGA gain can be kept at 35 dB.

Thanks and regards,

George