Additional Notes on Cheap and Easy SDR

I’ve been doing some additional work with the Cheap and Easy SDR as discussed in the article in January 2013 QST by Robert Nickel. My original article on the Cheap and easy SDR is here.

Cheap and Easy SDR, system

My computer is a Pentium 4 running at 3.0GHz and I have 3GB of RAM in the system. The OS is Windows XP-SP3
In the below graph you can see the approximate processor load versus FFT size using the C# SDR. The two sets of data correspond to two different window sizes on my computer screen. One is the smallest I could make on my machine which was 700 pixel wide by 400 tall. The second is for 1200 by 400.

Cheap and Easy SDR, a graph

Cheap and Easy SDR Performance Graph

Note: the X axis is a logarithmic scale, I used powers of two to match the FFT size.

The Y axis is CPU usage shown in the Windows Task Manager Performance pane. I set the parameters and then watched where the graph seemed to steady out. So if you believe that you might be processor limited, the best thing to do is to make the window as small as possible so the processor isn’t bogged down making and updating a pretty picture.

I believe the reason the the curve fit is better for the larger picture is because the cheap and easy sdr was running at a higher overall processor loading so the other stuff the PC was doing had less of an impact on the variability of the numbers.

Let me know what you think of my analysis. does it help you?

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