Collecting Data from the Radio Telescope
So, continuing from the previous part - Building a Radio Telescope, this post will cover the data collection and analysis part of my project. BTW, this post will be very intensive in terms of technical language used. So, be warned. But i suggest you read through it anyway ...
There are surely a lot of different ways to go about saving data from a radio antenna and use analyse the data on a computer but well, i couldnt find them. And the method of data collection mentioned here, where they use a modulator and down convert the original signal to the range of Hz and feed this signal into the audio jack of a computer. And using the relevant Sky Pipe software, you can analyse this signal for radio bursts from the sun and signals from jupiter. You can save this data from the program onto .png files or .txt files, archives of saved data which are available here
But, i don't think that this is an efficient way to save and analyse this data.
So, i suggest another method, which has been working fine so far.
I suggest using a Digital Oscilloscope (model : TDS 1001b) to sample the high frequency signal we get from the antenna which are in the range of ~MHz (which is possible as these oscilloscopes have a max. sampling frequency of 50MHz and a sample rate of 1GS/s) and view the signal in this digital oscilloscope. As these oscilloscopes have inbuilt FFT functions, we can look at the fourier spectrum of the signal as well. But im not exactly satisfied just being able to look at the fourier spectrum on the oscilloscope, i want to be able to save the data on a system, for easy data analysis.
The good news is that these oscilloscopes come with a USB output interface and the company (Tektronik) provides free software to view the signal from the oscilloscope on your computer. TekVISA is an essential software which installs all of the necessary drivers for the USB connection and also a basic program which will let you look at the signal on your computer (you wont be able to do anything more though). You'd have to be registered on the website to be able to download the software and relevant drivers. And now that we have a USB connection from the oscilloscope and we have the relevant drivers installed, we move on to other ways by which we can access this data.
(this is a bit tricky, unless you try this hands-on. and refer to the step-by step video in the references i mentioned, for a better understanding of this)
now we get to the part of using MATLAB to do data analysis. The data acquisition tool box in matlab lets you control a digital oscilloscope (given the drivers are previously installed and a specific matlab file is available). This specific matlab file should be downloaded and copied onto MATLAB's working directory, so that the data acquisition toolbox can identify the oscilloscope (if the file isnt already available i.e).
Now that you have the relevant drivers and the matlab file as well, after you connect the oscilloscope to the comp, you should be able to see a new device under the USB option, which is your oscilloscope. Add the device in the new devices option and connect it.
Test the device by auto-setting the oscilloscope through matlab and other basic operations.
Now that we're connected to the device through matlab, you should be able to see options such as 'Read Waveform', 'Write Waveform' etc. Now, set the options to 'channel1' and 'y,x' and run the command. after the data has been retrieved from the oscilloscope, you should be able to see an export option. and this will help you export this saved data onto the matlab workspace.
And well, now that we have the data on the matlab workspace, we can do pretty much everything we want to do from averaging multiple samples of the same signal, FFTing the signal to look at the fourier spectrum or pretty much whatever we want to.
Obviously, unless you actually try this, you wont be able to understand the process and the different steps involved, though i mentioned them to you. So, if you are doing something even vaguely related to making circuits and testing their response functions, or basically anything which involves electronic circuits - you should try getting your hands on a digital oscilloscope and try this out.
And this isnt the only kind of digital oscilloscope which matlab supports. There are already pre-installed matlab drivers for products from a range of manufacturers. So, check them out as well.
- the oscilloscope model i mentioned above which i've been working with.
- the different models of tek oscilloscopes which are supported by matlab.
- a webinar on how to acquire live data using the Matlab.
- a step by step tutorial on how to connect the oscilloscope to matlab and start using Matlab - very very useful and basic!
Well, do tell me if you try this out and i welcome info about updates on the software or drivers used. And if you've used this method before, do tell me how you went about doing it, how different you did it and what you were able to achieve.