Direction finding - Hardware selection

[Venkat RAM]

Hi Team,

I am initiated working on Direction finding 

here my first challenge is to select device

I need to work on AOA concept to find the the person inside the room or outside the room  based on direction finding by keeping the RX device at the entrance of the room 

i have confustion to choose from nrf52833 and nrf53840, because

1. form nordic webinar they mentioned nrf52833  is fully qualified HW and SW solution

2. But in this following page https://www.nordicsemi.com/Products/nRF5340  at "Comparison of our Bluetooth LE SoCs" 

they mention as

SoC	nRF5340	nRF52833
Flash	1 MB + 256 KB	512 KB
RAM	512 KB + 64 KB	128 KB
CPU	128 MHz Arm Cortex-M33 + 64 MHz Arm Cortex-M33	64 MHz Arm Cortex-M4 with FPU
QSPI	Yes
Packages	aQFN94 WLCSP95	aQFN73 QFN40 WLCSP76

I need to choose highest grade specification for by development

kindly suggest me a board model  for RX in AOA , SDK version 
and theoretical concepts for Connection less locator because i plan to single antenna device for  beacon (nrf52840)

Thanks in Advance

Best Regards,

Venkatraaman J S.

[haakonsh]

nRF52840 does not support Direction Finding.

Read the Direction finding connectionless locator sample documentation, and pay attention to Rquirements and Antenna Patterns.

Reference reading:

• BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 1, Part A, Chapter 8 DIRECTION FINDING USING BLUETOOTH LOW ENERGY
  
  
• BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 6, Part A, Chapter 5  ANTENNA SWITCHING
  
  
• BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 6, Part B, Chapter 2.5 CONSTANT TONE EXTENSION AND IQ SAMPLING

Note that sampling IQ data and processing it correctly it is not trivial, and there is little available support resources for small projects. 

[Venkat RAM]

"nRF52840 does not support Direction Finding." 

means it does not support even for Transmitter of AOA right?


For both RX and TX need to choose only from the below soc right?

nRF5340 SoC
nRF52833 SoC
nRF52820 SoC
nRF52811 SoC

[haakonsh]

Yes, that is correct. The nRF52840 does not support Continuous Tone Extension. 

CTE is a constant carrier (pure sine wave) used as the reference signal for gathering IQ datapoints. See https://en.wikipedia.org/wiki/In-phase_and_quadrature_components.

[Venkat RAM]

Thanks haakonsh,

"To successfully use the direction-finding locator when the AoA mode is enabled, provide the following data related to antenna matrix design:

• The GPIO pins to dfegpio#-gpios properties in the nrf52833dk_nrf52833.overlay file.

• The default antenna that will be used to receive a PDU dfe-pdu-antenna property in the nrf52833dk_nrf52833.overlay file.

• Update the antenna switching patterns of the ant_patterns array in the main.c file."
  
  Direction finding - Hardware selection
  

based on the above ref nRF52833 DK  suits for AOA Concept development

but I am confused about the CPU, RAM are highly graded in. nRF5340  at progressing

Kindly clear my query

[haakonsh]

Hey Venkat,

Venkat RAM said:

but I am confused about the CPU, RAM are highly graded in. nRF5340  at progressing

I don't understand what you are asking for, can you rephrease your question?

BR,
HH.

[Venkat RAM]

Hai haakonsh,

here in nrf5340, ram, CPU, and flash memory were high,

but in nrf52833, is less which is shown above in the above comparison chet above

In the nrf community  blog, they instructed, for Processing the IQ data needs more RAM

is nrf52833 spec okay for direction finding process, or can I go ahead with nrf5340

For my application, I need to find direction finding for multiple devices at the same time

suggest one model, kindly share the reason, i will usefull for my development purpose

[Kenneth]

Please refer to the documentation for what hardware is supported:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/direction_finding_connectionless_tx/README.html 
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/direction_finding_connectionless_rx/README.html 

The nRF52833 is a good fit for direction finding.

Kenneth

[Venkat RAM]

thank you so much kenneth