zorgrian

modified 5 years ago

📻SIMPLE quadrature SDR📻

288

02:25:58

Software Defined Radio
THE DIODES ARE FED WITH 0 AND 90º PHASED SQUARE WAVES

📻UPDATE📻
In order to understand I & Q more properly watch this video by w2aew: 

https://youtu.be/h_7d-m1ehoY

- This corresponds to 0% phase delay & 25% phase delay respectively
- QSD is @ 10kHz
- input is 1kHz, which may be a bit too low so now increased to 8kHz
- this did not work well so it is now @ 3 kHz
- the thing works best here with the input signal @ 100 mV

published 5 years ago

fatcat2

5 years ago

@zorgrain, what is this circuit actually? I don't see any sampled input signal at the output.

Archit404

5 years ago

[BLOCKED]

Archit404

5 years ago

[BLOCKED]

Robert_Kidd

5 years ago

@Archit404, the author has taken time to produce this circuit and present it here. Perhaps you should respect him for that and not litter it with nonsense.

zorgrian

5 years ago

The two phases switch signals provide 0° and 90° phase sampling of the input frequency. This is the basis of QSD quadrature sampling detection

zorgrian

5 years ago

Thanks @RK I was trying to share ideas on QSD so, honestly @A404 is out of order here

zorgrian

5 years ago

It seems that A404 is a troll with no circuit published

fatcat2

5 years ago

I think that the output is not in shape with the input because the sampling frequency is too less. Can I change the LO frequency to, say a 100kHz without changing the design? A sampled signal resembles the main signal, right?

zorgrian

5 years ago

You can change it however you like.

zorgrian

5 years ago

Yes if you put a 10 khz signal into the sampling detector you will get two waves out @ 90° offset

fatcat2

5 years ago

Fine

zorgrian

5 years ago

Check this video

zorgrian

5 years ago

https://youtu.be/h_7d-m1ehoY

fatcat2

5 years ago

Thanks @zorgrian. The video was really informative.

zorgrian

5 years ago

@F you're welcome. Here, tho in this circuit a MUX CMOS switch is not used. Instead diodes are used as are commonly used in RF analogue frequency mixers. Diodes are nowhere near as fast as modern CMOS switch chips. However, I have been experimenting with Schottky diodes, which are fast as they don't have a PN junction

fatcat2

5 years ago

What is a MUX CMOS switch?

eframgoldberg

5 years ago

Multiplexed I think

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.