RSSI and TX power from nRF 52

RE: RSSI and TX power from nRF 52

Kaja — Wed, 11 Aug 2021 13:52:47 GMT

Hi,

we usually don't do much impedance measurements of the radio, as tuning the radio by measuring output power and harmonics are more efficient. But doing impedance measurements of the radio you need to measure from the radio matching network, towards the radio.
From point B, looking towards the radio, point 2. The RF path towards the antenna, must be cut so that you don't get an extra load.

You can measure S22 if you put the radio in TX mode (constant, unmodulated carrier) and measure into the matching network, point 2. You should see an impedance closer to ~70 ohm because this gives the best operating conductions (less harmonics) for the PA.

Best regards,
Kaja

RE: RSSI and TX power from nRF 52

PATA — Tue, 10 Aug 2021 07:22:24 GMT

Hi Kaja,

Thank you for your help. I will try to use DTM and radio test.

In the meantime, can you please let me know more details about impedance measurement?

I'm using network analyzer (NA) and my target device is nRF52, but I'd like to know which nRF codes or program I need to run to test each impedance during TX mode and that during RX mode.

Thank you,

RE: RSSI and TX power from nRF 52

Kaja — Tue, 10 Aug 2021 07:17:54 GMT

Hi,

[quote user="Kaja Soerbotten"]Have a look at out white paper RF measurements[/quote]

You can use DTM, direct test mode or, the one recommended for this measurements, radio test example.

[quote user="PATA"]Also, I'd like to learn about the setup for impedance measurement (S11) during TX mode.[/quote]

Then you would use a VNA to measure on the output, instead of a signal analyzer.

We offer to do free HW review of designs, RF measurements, tuning of the radio and antenna.
To get this service, please create a private DevZone ticket, use the topic HW verification, and upload HW files, both schematic and layout.

Best regards,
Kaja

RE: RSSI and TX power from nRF 52

PATA — Mon, 09 Aug 2021 20:52:57 GMT

Hi Kaja,

For that sentence, I was meaning RSSI measurement results, rather than TX output power.

Can you please let me know more details about the setup for TX power measurement?

I'm trying to measure the TX output power of nRF52832 by using advertising mode and the setup described in https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52832_dk%2FUG%2Fnrf52_DK%2Fhw_rf_meas.html.

But it seems like we need to use a proper data pattern.

So, can you please share the codes that can be used for TX power measurement?

Also, I'd like to learn about the setup for impedance measurement (S11) during TX mode.

It will be highly appreciated if I can get your urgent assistance. Thank you in advance.

RE: RSSI and TX power from nRF 52

Kaja — Fri, 06 Aug 2021 12:25:00 GMT

Hi,

I'm a bit unsure what you mean when your say:

[quote user=""]Firstly, we set DK board to output 0 dBm, and theoretically it should have shown -30 dBm, but we could get only -47 dBm.[/quote]

Do you set the DK to a constant carrier with 0 dBm? Then you should see ~0 dBm.

Have a look at out white paper RF measurements

Best regards,
Kaja