nRF52840 Coded Phy Range Problem

[Aamir]

Hi,

I am using nRF52840 Enineering C chip on a custom board using SDK v15.3.0 with SoftDevice v6.1.1

I have modified the Blinky Central code and the Blinky Peripheral code to work in Long Range mode using Coded Phy.

The receiver on the Central is ON 100% of the time, and the peripheral is advertising at 100 ms interval.

The Range results I got while changing the tx power of peripheral is as follows:

Coded Phy 8 dbm tx power - 250 meters

Coded phy 0 dbm tx power - 170 meters.

1MBps Phy 0 dbm tx power - ~100 meters

1MBps Phy 8 dbm tx power - 150 meters

This is way less than expected, how can the range be increased further ?

[Simonr]

Hi

Have you set the advertising type to extended (BLE_GAP_ADV_TYPE_EXTENDED_CONNECTABLE_NONSCANNABLE_UNDIRECTED)? What is your advertising flag set as? This needs to be "BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE". Both these parameters are needed for long-range mode to work.

In what environment have you tested this setup? It should be tested outside where the chips are in field of view of each other and without too many interference sources, or else you can experience notable range loss.

Seeing as this is a custom chip, it could also be that your antenna is not very well suited for long-range applications. You could test if this is the case by using two nRF52840 DKs instead to see if the range changes. What antenna have you used, and how does your matching network look?

Due to the summer holidays in Norway, our support team is understaffed this week, and delayed replies must be expected. Sorry for the inconvenience!

Best regards,

Simon

[Aamir]

Hi Simonr,

Yes my advertising type is BLE_GAP_ADV_TYPE_EXTENDED_CONNECTABLE_NONSCANNABLE_UNDIRECTED

and the flag is set to BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE

Yes, we did this test outside and both the device were in field of view of each other, but, I can't be sure about interference as there were many Wi-Fi devices around in range.

We have CERAMIC PATCH ANTENNA with dimensions 8 mm x 1 mm  

the antenna is identical on both the Central and the Peripheral device.

Even though you could see the pcb under the antenna, but it is just a layer of pcb and does not have ground or power plane  or any kind of track beneath it.