Radio frequency generation

RE: Radio frequency generation

JONATHAN LL — Thu, 25 Jan 2024 13:03:47 GMT

Correct, you can use the radio test sample and use the commands there to sett channel and power. Then just measure the Delta offset and you see the ppm of the crystal.

So let say we set the 02, and we get this

Then the delta offset is 17.950kHz, 17.950kHz/2.402GHz = 7.472939 ppm, that is within the spec, so considered good result.

Regards,
Jonathan

RE: Radio frequency generation

rasmus_sigma — Thu, 25 Jan 2024 12:50:31 GMT

Thank you for the awnser.

Okay, so if the TX wave differ from the chosen channel frequency the HFXO is off?

We are measuring the frequency already with a spectrum analyzer so that is not a problem.

Regards,

Rasmus

RE: Radio frequency generation

JONATHAN LL — Thu, 25 Jan 2024 09:29:07 GMT

Hi,

The HFXO is responsible for the carrier frequency that is used, its accuracy is only possible to measure by measuring how accurate a constant carrier TX wave set to a specific channel. Then measure the accuracy of that signal with a spectrums analyzer.

It is of no value to measure directly the crystal it self at any probes or direct contact will alter the load that the crystal sees and change the result.

The LFXO is responsible for the timing. But its accuracy can me measured as well. See this comment: https://devzone.nordicsemi.com/f/nordic-q-a/41549/test-the-accuracy-of-external-lfclk/162029

Regards,
Jonathan