Bit Error Rate (BER) measurement between an nRF52840DK board and a BC840E

[Leonardo Balocchi]

I am using an nRF52840DK and a BC840E and need to perform a bit error rate test.
Is there an example that allows me to measure the Bit Error Rate (BER) between ke two boards or directly from the "radio test" application send a series of known bits (bytes) and then see which bits arrive right and which arrive wrong at the receiver?

[Håkon Alseth]

Hi,

 

To check the packet error rate between two nRF's, you can use the radio_test, similar to what is described here:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html#testing-with-another-development-kit 

I would recommend that you use a random byte pattern instead of 0xf0f0f0f0.

 

Please also note that the command "start_tx_modulated_carrier" can take in the amount of packets that you want to send as well.

 

To calculate BER from PER, you can use this formula:

PER = 1 - (1-BER) ^ num_of_bits_in_packet

if you have a 46 byte payload, the calculation looks like this for a target of 0.1 % BER:

PER = 1 - (1 - 0.001)^(46*8) = 30.8%

 

Kind regards,

Håkon

[Leonardo Balocchi]

Hi Hakon,
I thank you for your answer.

I wanted to ask you how I can set the number of packets to be sent within the "start_tx_modulated_carrier" command. If you can, can you send me the documentation on the arguments you can give to the start_tx_modulated_carrier function and give me an example of the syntax for sending a predefined number of packets?

Then I also wanted to tell you, that in order to calculate the BER I should have saved somewhere the bits that were sent and the bits that were received.
The received bits I can see from serial by keeping the receiving card connected to the PC. But for the sent bits, how can I see them, and then be able to calculate the BER, as the number of erroneous bits between the transmitted and received bits?

Thanks,

Leonardo

[Håkon Alseth]

Hi,

 

Leonardo Balocchi said:

I wanted to ask you how I can set the number of packets to be sent within the "start_tx_modulated_carrier" command. If you can, can you send me the documentation on the arguments you can give to the start_tx_modulated_carrier function and give me an example of the syntax for sending a predefined number of packets?

You provide a number after the command.

For instance: start_tx_modulated_carrier 1000

 

Remember to setup the second device in RX before executing the above command.

Leonardo Balocchi said:

Then I also wanted to tell you, that in order to calculate the BER I should have saved somewhere the bits that were sent and the bits that were received.
The received bits I can see from serial by keeping the receiving card connected to the PC. But for the sent bits, how can I see them, and then be able to calculate the BER, as the number of erroneous bits between the transmitted and received bits?

Use the formula that I posted previously to calculate BER from PER.

The default is to send with a full payload, ie. 255 bytes of user data (127 for 802.15.4). You'll need to manually add preamble, crc etc.

 

Kind regards,

Håkon