Gain of the PCB antenna of the nRF5340-DK

[Theodorul]

Hello, I am trying to estimate the distance between two nRF5340-DKs using the Friis transmission equation, but I do not know the gain of the on-board PCB antenna. What is its value or how could I measure it?

Thanks in advance!

[Elfving]

Hello Theodor,

I can look into that for you. But first of all, I would recommend you to use other ways of measuring the distance than only using the RSSI. For more info on why, see here.

The Nordic distance toolbox provides the friis estimation, as well as other estimations that are far more accurate. For an NDT sample, see here.

Please let me know if you still want me to look into this :)

Regards,

Elfving

[Theodorul]

I would like to implement an indoor positioning system on my own, for this I have 3 ESB advertising beacons which continuously transmit data to a mobile receiver. The receiver fetches the RSSI value of each message and transmits them to a nRF52840 beacon which is connected to a laptop running a MATLAB interface. I want to process all the data in MATLAB as I am not resource-restrained in this way.

I currently placed the receiver in several fixed locations, made 100-ish RSSI measurements in each location and trained a neural network which should now be able to associate a random (RSSI1, RSSI2, RSSI3) value to a before-mentioned position.

The problem is that it is still quite noisy and I would like to improve it by also calculating the distances using the Friis equation, and correlating the conclusions, but for this I would need to know the gain of the on-board antenna of the nRF5340-DK.

Thanks!

[Elfving]

Alright Theodor, though keep in mind that reflections etc. might make RSSI and friis path loss difficult to use on its own (as shown in the graphs in the webinar). Some argue though, that if it is filtered it can atleast be used as a lower estimate (the distance would have to be greater than this).

The gain of the PCB antenna of the 5340DK is 0 dBm.

Regards,

Elfving