IQ .wav files into an array?

Hi,
Following up from a previous question. I have a signal which comes from an RTL-SDR and I am trying to understand what I am seeing when Matlab gives me an array from a Simulink 'To Workspace' block. I think I am seeing a number and a complex number as shown below:
Represented in the variable as:
The diagram I have atm is:
The reason I want to understand it is I would like to be able to find where a spike is in the array and then grab a range for analysis. So if the spike is in position 100 then I want to take the values from 90 to 110 for example. On top of wanting to know what I am seeing it would be useful to know what it represents. How do you go about identifying a spike or pulse in the signal?
Any help greatly appreciated.

2 comentarios

Rik
Rik el 25 de Jul. de 2020
If you want to fully visualize a 2D complex array you will need 4 dimensions. That hints at a fundamental question: what do you define as a spike?
If you attach your variable in a mat file we can use your actual data in any example.
Colin Crook
Colin Crook el 25 de Jul. de 2020
Hi thanks for the response. So my quest into Matlab was to see if I could use it to identify a short burst of LoRaWAN communication from one of my nodes. My nodes hang off a Linux box with a duff hard drive so I have the burst recorded successfully with SDR# but not Matlab so far so I only have a default frequency with random noise. I did think there was enough variation in the Matlab recording though to give me a clue as to how the array behaved to then apply it further.
The file for matlab is attached. For interest the here is a screen from SDR# if it helps at all:
I am getting a new drive tomorrow so I will try to get it recorded with Matlab. The other option I guess is to try to read an IQ.wav file in with the burst included and see what data that gives to compare to the array I am getting. I have no idea how to do that though lol. When I was trying I was messing about with a bit of code I couldn't really get to work.

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el 25 de Jul. de 2020

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