SDR: The Executive Summary

One of the RTL2832 dongles I ordered from Ebay finally arrived. The other I have chalked up as a no-show. I’ll try to get my money back, but even if it turns out to be a loss the total cost for both was under $20. That’s very cheap for a software defined radio.

The executive summary: using a general-purpose computer instead of a traditional radio interface generally sucks from a user-interface point of view, but it has its one very intriguing and useful aspect. That latter is how an SDR captures a whole swath of spectrum and typically has a waterfall display to visually plot what it receives.

It’s a most useful feature when searching for non-broadcast signals; one doesn’t have to rely on chance for the particular frequency one is listening to to become active. Instead, you can see activity as it appears on any nearby frequency in the range being displayed, and immediately point and click to tune to it.

I’d suspect the sucky parts of the user interface aren’t nearly so bad with some other SDR programs. Right now I’m using gqrx, because I have only Macs in my house and gqrx is basically the only SDR software that runs on a Mac. I’m going to be getting a dedicated Windows machine soon (there’s enough software I want to run that only runs on Windows that it’s become worthwhile to do so), and once I have that I’ll be giving some other software a try.

Hardware wise, an RTL2832 isn’t exactly the greatest receiver. It’s sensitivity isn’t that great and it’s full of birdies (I suspect a better antenna, further from my computer, would help with some of that). Even my 25-year-old Bearcat scanner runs circles around it. But what can one expect from a consumer-grade device that didn’t even cost $10? It is what I purchased it to be: a low-cost way to experiment with SDR.

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