Please help me understand the oscillescope reading of my NRF24L01

RE: Please help me understand the oscillescope reading of my NRF24L01

Roger Clark — Sun, 22 Jan 2017 22:46:13 GMT

No worries.

Please accept the answer if you think its useful, otherwise it remains open and Nordic have to close it themselves (manually)

Good luck with your project.

I hope your professor understands when you tell him your initial hypothesis and method was possibly not correct and that you need to investigate this another way.

RE: Please help me understand the oscillescope reading of my NRF24L01

Dkraemer — Sun, 22 Jan 2017 21:56:37 GMT

Ha, well, my prof is doing some big research so he doesn't seem to have a problem getting grants. It's not a univesity/lab scope, it's one specifically for his research project(s). Yes, we matched the antenna. And there is WiFi running around but the output of the NRFL has 4 possible levels, so I set it to max level (0 dBm) and we stuck the NRFL right ON the antenna to maximize SNR.

I don't know that I actually need to decode it though? Maybe I'm looking at this part of the project all wrong. I thought that I would be able to count the times the frequency increased/decreased and see exactly where in the transmission my message was being sent. But it sounds like this may no be possible.

A quick look at the main site the link you sent me to says that I am not looking at this in the correct way. Not gonna be fun to tell my prof this. :/ Thank you for your help!

RE: Please help me understand the oscillescope reading of my NRF24L01

Roger Clark — Sun, 22 Jan 2017 04:38:42 GMT

Wow

13Ghz Scope, you must go to a high class university ;-)

I presume you have the correct matched connections for the scope to connect to the antenna impedance of the nRF24.

I don't know much about the nRF24's RF modulation, but it may also employ frequency hopping like BLE does, which will make things even harder to decode. (well, if you are just tapping into the antenna, and don't have any other RF signal interference then I wideband receiver would suffice.

I presume the data is also encrypted.

Edit. See my updated answer for another approach

RE: Please help me understand the oscillescope reading of my NRF24L01

Dkraemer — Sun, 22 Jan 2017 03:03:23 GMT

The scope I'm using can go up to 13GHz. It's being used for milimeter wave research so I know it can get the waveform.

I know the nrfl uses other data. I've read the packet extensively, all 78 pages of it. I know the format of the packet that's sent. It uses GFSK which isn't terribly complex but decoding that modulation is something I'll look into/didn't think about.

RE: Please help me understand the oscillescope reading of my NRF24L01

Roger Clark — Sun, 22 Jan 2017 02:50:46 GMT

Attaching a scope to the antenna is not going to give you useful data

For a start, the nRF24 transmits on 2.4Ghz (thats 2400 Mhz), and its unlikely that the scope you have will get anywhere close to being able to resolve that frequency, unless its a very specialist piece of equipment.

In addition to that, the nRF24 is unlikely to just transmit the exact data you sent to it. The data is encoded into the nRF24's data protcol which will have all sorts of other data in it which is sent

On top of that you'd have to decode the modulation method used by the nRF24 etc etc

I'd recommend you fully read all the available documentation on the nRF24 before you continue.

Edit.

Based on your feedback, I'd recommend you checkout this link

www.rtl-sdr.com/.../

I think its a better solution to what you are trying to achieve than using a scope