Using NRF Connect RSSI viewer with radio test sample

[Midhunjac]

Hi

I am working with the radio test sample. I am using the RSSi viewer for testing as detailed here. I am guessing that I need two development kits here - one with the sample flashed (A) and another one that is connected to the PC with RSSI viewer (B). The RSSI application programs the device B. This is my understanding about the setup. However, even without my device A powered down, I can see some activity in the RSSI viewer. I have no other bluetooth devices in the vicinity. Hoping to see a change in the observed pattern, I turned the device A on and used the following commands

output_power pos4dBm

start_tx_modulated_carrier

However, I could not see any change in the RSSI viewer. Is there anything that I am doing wrong ?

Also, I tried using the testing method using another DK as described here. This time, I could see the received packets but I cannot see any changes when I use print_rx on B when i change the output power of device A. How do I analyze the pattern ?

Thank you

[haakonsh]

Yes, that is was I expect as well. I checked the shell commands for the sample, it only accepts the values pattern_random, pattern_11110000, and pattern_11001100 as values for transmit_pattern.

Can you share a transcript/log of the shell sessions for the transmitter and receiver? I just wanna double-check that it is set-up properly.

As for a HW design review I suggest you open a new 'private' ticket and ask for a HW review. You can link to this ticket and it'll be delegated to me if I'm available.
We will need schematics and layout files, as well as a BOM for the crystals and passive components in the RF domain.

[Midhunjac]

Hi,

Here is the log. I believe it is working as it should be. The only problem I have here now is that I have no way of verifying the output_power set by the transmitter. Is there some way i can verify that too ?

Thanks

[haakonsh]

Midhunjac said:

The only problem I have here now is that I have no way of verifying the output_power set by the transmitter. Is there some way i can verify that too ?

I would start by calling parameters_print on the transmitter, after you've set the new TX Power value, just to verify that the radio test application believes it's in the correct state.

Then I would use the RSSI viewer on a third device (nRF52 series DK ), and set it to scan on channel 0 ( == Start Channel). If you place the transmitter right next to the RSSI measuring device (third device, dk) it should be the largest signal 99% of the time and that should enable you to measure a difference of ~4dBm, given that you do not change the positision of any of the devices between measurements.

Note that the RSSI cannot give you the absolute value of the transmit power, for that you need a conducted measurement from a properly calibrated signal analyzer rated for at least 2.5GHz.

We can do that for you as part of our pre-certification scan and antenna tuning service if you do not have the means to do so yourself.

[Midhunjac]

Hi,

Thank you for your input. I'll try this and let you know.