RF test in production

[Aurele]

Hello,

We are designing a product that is coming in production. We have been told that for production the "radio_test" example project was enough for general RF testing. But the production team asked some features such as BER (bit error rate) ... i don't know if it is possible to get this information with the radio test example. Moreover, i saw that some application note have been written for setting up the DTM for production test. 

So my question is the following : 

- what is the best to do on a production line : use a simple radio test or use DTM combined with Anritsu MT8852B ?

Thank you in advance for your help,

Best regards,

Aurélien

[Jared]

Hi,

I think the radio test would be better for production but it doesn't give you the bit error rate, neither does the DTM example. The latter however gives the packet error rate which is closely related as explained here. Do you need to check every sample in production or would it be enough to measure on a prototype?

regards

Jared

[Aurele]

Hello Jared,

Thank you so much for the reply. Yes, every devices will be tested. But in the end, all the tests will be automated on the production line so the less it lasts, the better. I wanted to use the radio test firmware on my DUT and on a nordic DK. Then a python script would have monitored both devices. So, according to you "radio test" would be better to test the RF, but what kind of test can be performed with this firmware : 
 - checking every channel RF emission ? 

 - RSSI check ... ?

Best regards,

Aurélien

[Jared]

Hi,

If you're going to test every sample during production, then I don't think the DTM example is appropriate, it should rather be tested with a porotype once. The radio test example lets you do TX and RX sweeps so that you can check that the device performs well over the different channels in the band. In addition it lets you setup a constant carrier, modify the tx power, data rate, or set transmission pattern. You can test the board with our DK by setting the DK in RX mode, it will then print out the data it receives from the DUT. The example is explained in further detail here. If you use the nRF Connect RSSI Desktop app, then you can measure the RSSI over each channel in the spectrum while the DUT runs the radio test example. 

regards

Jared 

[Aurele]

Hello Jared,

Indeed, using radio test example for the production was my first idea but i cannot find simple test to proceed to validate the radio. 

I found this : 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html

The only test i can do is the following one : 
- configure the TX board
- configure the RX board
- send "start_tx_modulated_carrier" on TX board
- send "start_rx" + "print_rx" on RX board
- check if i have received 256 data with the configured pattern on the RX side

Fianally, i really wonder if this test is worth it, because i guess it can be successful even if there is an hardware issue on the DUT. So, in the end, i think checking RSSI could be enough. I have tested the RSSI desktop app (RSSI viewer) with a nrf52840 dongle, this is a very good app but do you know another app with which i can easily interface (over UART) to be integrated with the production bench : i'm planning to write my own firmware (BLE central app) that will be able to connect with any peripheral. But maybe some desktop app exist (using any bluetooth dongle)

Thank you in advance

Regards,

[Jared]

Hi,

Aurele said:

Indeed, using radio test example for the production was my first idea but i cannot find simple test to proceed to validate the radio. 

I found this : 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html

The only test i can do is the following one : 
- configure the TX board
- configure the RX board
- send "start_tx_modulated_carrier" on TX board
- send "start_rx" + "print_rx" on RX board
- check if i have received 256 data with the configured pattern on the RX side

Fianally, i really wonder if this test is worth it, because i guess it can be successful even if there is an hardware issue on the DUT. So, in the end, i think checking RSSI could be enough

Sounds reasonable.

Aurele said:

So, in the end, i think checking RSSI could be enough. I have tested the RSSI desktop app (RSSI viewer) with a nrf52840 dongle, this is a very good app but do you know another app with which i can easily interface (over UART) to be integrated with the production bench : i'm planning to write my own firmware (BLE central app) that will be able to connect with any peripheral. But maybe some desktop app exist (using any bluetooth dongle)

We do not have a ready app for this, instead you would have to use the PC-ble-driver framework to create your own desktop app that does this. The framework lets a desktop app use a nRF device as a connectivity chip. Which means that you can get access to the Softdevice functionality in the desktop app. You can find the documentation for the framework here.

best regards

Jared