IQ, Image Reject, and Single Sideband Mixers Demystified

[@NoMercyXtreme]

Great talk. Thank you very much. I am working on my master's thesis at the moment. We had IQ mixers in our courses, but they were poorly and not entirely explained. This helped a lot. I am even using a Marki IQ mixer, seems like a great company.

[@terjeoseberg990]

It’s just trigonometry. Multiplying sines and cosines of various frequencies.

[@RobertSzasz]

I've always thought of I and Q as sine and cosine. With control over both you can put your signal anywhere with the circle your modulation bandwidth allows.

[@terjeoseberg990]

Exactly. That’s what it is. Basically your signal is on a ribbon, and your sine and cosine create a rotating unit vector. When you send your signal through the mixer, the mixer twists the ribbon at a twist rate equal to the frequency of the local oscillator. The two outputs then slice the twisted ribbon in the horizontal and vertical direction. The two new signals on the vertical and horizontal slices both consist of signals which are the sum and different between the frequencies of your input and the local oscillator.

[@1988198k]

Wow ..just wowo ..slide 6 is great for me

[@RobertSzasz]

Oh, and I think a discrete t flip flop is used in the softrock SDR

[@terjeoseberg990]

The discrete flip flop creates square waves. How does this impact the performance of such a mixer? It seems like it would cause a lot of sideband noise/interference.

[@johnbarber1482]

What I hate about enineering is that we talk all this math and "procedures" but how the hell are you supposed to implement this crap? As an ECE Senior with a 3.8 GPA, I feel like i have alot of useless information that I can't do anything with because schools do a horrible job at application. I feel like I wasted a few years out of my life that i'll never get back. Engineering Schools are the worst.

[@terjeoseberg990]

Well, buy the components from these guys, and then you don’t have to worry about it. It’s just like playing with Legos.

[@dabdoube92]

Part of what this guy is saying doesn't make sense