Understanding channel select on radio test example

[Tandon]

Hello Nordic team,

I am trying to get my product read for FCC/CE compliance testing. I came across the radio_test example and other examples posted on DevZone. I have the following queries.

1) The Test lab wants me to test the product in 2402MHz, 2442MHz , 2480MHz. They want me to transmit in these frequencies separately. In the example channel is set to sweep from 0 to 80. Is it safe to assume that 0 is LOW; 40 is MED and 80 is HIGH? I am planning on doing a single channel sweep using 

radio_tx_carrier(txpower_, mode_, channel);
radio_tx_sweep_start(txpower_, mode_, channel, channel, delayms_);

txpower_ and mode_ are the default values. 

2) I do not have a spectrum analyzer, the infocenter piece explains that we can use a another board with the same example. Would this be in  rx_sweep mode? i am not very familiar with RF just yet so the more information provided would help me greatly.

Appreciate your time,

Tandon 

[Andreas]

Hi,

 

1. The sweep function is not quite what they are after, they are after a way to set the transmitter to 2402 MHz, 2440 MHz and 2480 MHz. The radio test example comes with a UART CLI that lets you configure this through a terminal, no reason to worry about the source code. Of course you could make separate images that set up the transmitter upon startup, it is all up to what you and the test house prefer.

2. No the receiver would need to run the start_rx command, with the same bitpattern, mode and on the same channel. You then need to use the start_tx_modulated_carrier or start_duty_cycle_modulated_tx on your DUT. You do not need to do this though, the transmitter just needs to transmit 'something', so you might find the RSSI App in nRF Connect for Desktop more convenient to prove this (this uses your 2nd DK as a makeshift spectrum analyzer).

 

Best regards,

Andreas

[Tandon]

How would I use the UART? nRF Connect app? I am a little lost. Thank you

[Andreas]

Hi,

 

See the testing section of the example documentation:

Test the Radio Test Example application by performing the following steps:

1. Compile and program the application.
2. Start a terminal emulator like PuTTY (recommended) with the related Terminal settings and UART and USB settings. The text "Radio test example started." appears at the top of the terminal.
3. Open a serial connection to the COM port used by the tester board. A command prompt is displayed.
4. Type any of the CLI commands described above. An output text is displayed in the terminal emulator window, and the sweep or the signal is started.
5. Depending on the testing method:
   • Use a spectrum analyzer to confirm the behavior of the radio module.
   • Use a second board configured in the same mode as the first one to receive the transmission, and type print_rx to print the RX data received from the other board.

 

As for step #2, see the link, but note that you need to go to the session category to start the UART terminal. If you need to figure out what COM port your DK is, see the device manager in Windows.

 

Best regards,

Andreas