Visualising Digital Communications: QAM with Real Signals
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- เผยแพร่เมื่อ 16 ต.ค. 2024
- Explores digital quadrature amplitude modulation (QAM) using real signals transmitted over a wireless channel from a software defined radio (SDR).
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Full categorised list of all videos with Summary Sheets: iaincollings.com
Never felt digital communication could be as simple what I see in this video. Thank you sir for making it happen. 😊
I'm so glad you liked the video.
I agree. Most people lead with the math, which is not very hard, but does not lead to an intuitive understanding (for me). Starting off with this very intuitive approach really helps me. It is amazing how the availability of cheap processing power has made desktop SDR setups like this easy to “play” with.
How can you be so knowledgeable and humble at the same time. Where you gather all these, I never learnt anything from my college, yet my degree says I'm a Communication Engineer. Lots of theories, earned nothing that I can apply to real life. But you are really fascinated by the way you convey those hard theories as simple as possible and delivering in a simple and practical manner.Never stop creating videos. Now I believe in God, and He is here. He has a body and face too, he who the one helps others who has a quest for knowledge. I'm so happy that I lived in an era, where I can see and learn a lot from Iain's videos. Wishing you the very best of happiness for your life. Love you Iain... ❤️❤️❤️
Thanks so much for your very nice comment. I am glad you are finding the videos helpful.
I like the way you presents these concepts in an easy way. I learn alot from you sir.
Cant thank you enough.
That's great to hear.
This is so cool , I have yet to start studying signal and telecomunication but this seems so fun. I had no idea this type of modulation existed. Can you reccomend some books about these types of modulations?
I've got lots more videos on my channel on related topics. I'd recommend watching them. They're listed in categorised order at this website: iaincollings.com
Complete Wireless Design, Second Edition
Always wanted to play with those SDR's on FPGA's...
Students at universities have so many awesome tools nowadays...
Waiting to see more videos with it 🙂
I'm glad you liked the video. I've got another one planned too.
@@iain_explains I look forward for it..
BTW. You've published very interesting number of videos - 256 😉
Nice pickup! 😁 Now I've either got to stop making videos, or make another 256!
Thank you so much٫ It was very helpful and intuitive
Glad it was helpful!
nice, thank you Iain
I'm glad you liked it.
Awesome video. Well done sir!
Glad you liked it!
Can you make a vid about improving channel reliability in this case ? Are there specific algorithms that can be used for example ?
Nice one, What is that software?
I believe its the LabVIEW NI-USRP, which is for NI universal software radio peripheral (USRP) transceivers and LabVIEW reconfigurable I/O (RIO) USRP devices.
I could be wrong though so double check.
@@jenis-01 Yes, you're right. It's the LabVIEW NI-USRP software.
Hello, short question about the DOPPLER shift impact on OFDM.
Do you have a video about that topic? believe it is not possible to just shift all carriers back for compensation. Thanks a lot.
Here's my video on Doppler and OFDM. It doesn't talk about how to compensate for it, but it does explain the effect, and by understanding that, it's clear that it's not a simple task to "just shift it all back" after the signal is downconverter and sampled. "Why is Doppler a Problem for OFDM?" th-cam.com/video/mB0GF9uKC48/w-d-xo.html
@@iain_explains thanks, I watched that video carefully. You mentioned this filter bank (for the subcarriers), we cannot adapt that bank because it is hardware? Is that right?
If implemented in software, it should be possible, I assume.
Thank you.
But they obviously make higher order QAM's work at 5.4 GHz, right ? So what do they do instead ? Must be more tricks
Well yes, there are always more tricks ... but my understanding is that this is just a basic software defined radio (SDR) implementation of a receiver, with what I assume is a basic synchronisation algorithm implementation. It's the software that came with the USRP - I didn't write it myself. Plus, as I said, it doesn't include error correction coding. And I don't know what the exact specifications are on the noise figure of the receiver amplifier. Lower noise amplifiers will give better SNR.
Ahhh OK. Non-optimal setup for that band. I saw the unit and software and assumed it was some expensive pro test unit. I need to look at this package. It's very interesting ! Thanks for the great video !
QAM-256 is the same at 30MHz or 5GHz; the higher the frequency the faster data can be sent... But also there's more bandwidth theoretically available, but losses are more significant over the same distance.
Also, I was doing QAM-2048 and 4096 over 192MHz channel at a previous job; around 130-300 MHz; could run multiple 192MHz continuous. Fun stuff.
@@jamess1787 Amazing ! QAM-4096 Yep ! Path loss is another important part of it. It looked like, from the setup, that RX and TX were right next to each other so should have been easy peasy :)
When I learn this everything was pure theory 😂😂😂 and the matlab simulation does not really help me visualize all of this. At some point I have to fill in the gap with imagination 😂😂😂