optimizing nRF5340 Audio application for maximum range

[JeraDrson]

Hello,

I am working on unidirectional voice broadcasting device where the maximum range is the priority. At this time I am developing on Audio DK boards.

I need some help to choose the correct settings.

16KHz/16b, single stream (mono) quality is good enough, audio latency is not important

I need some few bytes short custom data advertisement about 5x per second. No other communication is needed.

I made some adjustments in nRF Kconfig GUI to select the audio format, audio works but it is hard to tell the the sittings is close to optimal (tested outdoor range is about 150m with optimal antenna orientation).

I understand setting the device to coded PHY should help, however I do not know how to do that.

I added

CONFIG_BT_CTLR_PHY_CODED=y

CONFIG_BT_EXT_ADV=y

CONFIG_BT_USER_PHY_UPDATE=y

to the prj.conf but i get message that CONFIG_BT_CTLR_PHY_CODED  was set to n because of dependencies. I could not find any related options in kconfig editor.

Also how can i determine the number of retransmissions?

Thank you

Regards Jeronym

[Amanda Hsieh]

Hi,

Which NCS version are you using?

I added

CONFIG_BT_CTLR_PHY_CODED=y

CONFIG_BT_EXT_ADV=y

CONFIG_BT_USER_PHY_UPDATE=y

to the prj.conf

Please try to add those configs to hci_ipc.conf.

Regards,
Amanda H.

[JeraDrson]

v 2.6.1

I moved the option to hci_ipc.conf (i tried it before).

I cleared the project, restarted to visual studio and i no longer see the dependencies issues. Is there a way to know ir is really working? Maybe some debug prints?

[JeraDrson]

To be sure i have just created new build configuration. I left all the options untouched.

This is strange because i can now see the message with dependencies again.

I can see some information about the audio stream for example but nothing about PHY settings.

I also quickly tested the range and it seems about the same as before adding the options.

[Amanda Hsieh]

You should add the configs as this hci_ipc.conf:

CONFIG_BT_EXT_ADV=y
CONFIG_BT_CTLR_ADV_EXT=y
CONFIG_BT_CTLR_PHY_CODED=y

Make sure you add the coded PHY settings on both devices. 

[JeraDrson]

Hello, yes, this build correctly. But there it nothing in the log to on TX/RX side to confirm the correct settings. Tried "Project default" and "Optimize for debugging".
Also could you please give some insight regarding the other settings for maximum range?

[Amanda Hsieh]

Do you print phy info as this line on both sides to check?

You can refer to the Central Heart Rate Monitor with Coded PHY and the Peripheral Heart Rate Monitor with Coded PHY samples. 

[JeraDrson]

I can not do that. The phy member does not exist. This means CONFIG_BT_USER_PHY_UPDATE is not defined although i have it in the hci_ipc.conf as you advised.

I do not understand why the missing dependencies messages are sometimes there and sometimes not.

Could you please just try to build the audio application with coded phy on your size? I got stuck and need to move forward with this.

Thank you