QAM, QPSK Explanation, (PART 2 leading to 16QAM and more.....)

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/ robertjohnwebber
A continuation of the video "QAM, QPSK Explanation"
You can download an excel file from here to explain this better:
dl.dropboxuser...

[@rajatgupta6167]

People who disliked his videos please reply here because i want to know whats wrong with you guys this guy just taught a pretty hard topic in within a few hours keep up the good work man :) we love you

[@MrTadge]

Small mistake at the end, just incase anyone gets a little confused .... 64 QAM is 6 bits not 8. 256 QAM would be 8 bits Every time the QAM double you have to add 1 bit... Example 4 QAM = 2 bits 8 QAM = 3 bits 16 QAM = 4 bits 32 QAM = 5 bits 64 QAM = 6 bits And so on Great video explanation all the same. Well done !!

[@muhammadnajamulislam2823]

your math is bad brother .... 2^6 is 64 bit

[@muhammadnajamulislam2823]

2^8 is 256

[@noorassia4456]

can you send more explan and exercice like this QAM and QPSK

[@coltenharlan7161]

i realize it's pretty randomly asking but do anyone know a good place to watch new tv shows online ?

[@austinlane9154]

@Colten Harlan Try FlixZone. Just search on google for it :)

[@gireesht6752]

Thanks Mr Webber, missed a chance to say the same for last video. Highly recommended, he really goes through the idea with so much ease, that everyone understands !.

[@Corporate_Adda]

nice explanation now i understood this topic its better than that of boring colllege lectures thanks

[@richiewarner6399]

Hello Robert. Thank you so much for your time in explaining this. I am currently studying with the OU and I had trouble grasping the concept of QAM. Your video has helped me understand QAM, I now feel quite confident with the subject. Thank you very much. Rich

[@WEBBERSPADE]

Hello, You´re right that there are three output amplitudes, but 2 different input amplitudes for 16QAM. However the voltage values depends on the design of the transmitter/ receiver. For example a broadcast 1V signal wont travel very far! Thanks for the comment though Eder.

[@MidnightCloak29359]

thank you so much for this video! I've been trying to understand this concept for days for a project and you made it so easy! It really is a joy to watch your videos

[@chengdaniel7562]

THX a lot Robert. Your video is really really useful for me. Your course is simple but important, so that can make most people understand. THX again!!

[@786Poon]

Amazing explanation! It addressed the query I had for 2 years!

[@tfasm]

This is a great lecture. It was clear and easy to understand. It took some time that why 16 Qam has 2 amplitudes, but I found out that you correct it on the the video. I am going to watch it now~ :) Thanks.

[@hennny]

This videos (part1 & 2) helped me a lot! Thanks a lot, sorry i can't tell you how to make your videos better because for me the explanation was perfect! Greets from Germany!

[@WEBBERSPADE]

Hello, thank you for the comment, but I did correct it if you watch it on a PC. Only my 4th video, all in 1 take. Things have got better in my newer videos. Thanks again for the comment

[@yoniziskind2115]

Robert, you are THE man!!!

[@joaorenatomendes2200]

Thank you so much! I was trying to understand this for days!

[@WEBBERSPADE]

Hello nim7289, The three different amplitudes are available by a combination. Here's an analogy: Imagine I have 4 bags, two red, and two blue. Of the two red bags, one weighs 1 kg, and the other 2kg. The same with the two blue bags.One is 1kg, the other is 2kg. Then I've got a scale. I must put one of each colour bag on the scale So have these combinations: 1kg Red + 1kg blue = 2kg 1kg Red + 2kg blue = 3kg 2kg Red + 1kg blue = 3kg . 2kg Red + 2kg blue = 4kg 3 different weights!

[@sandeeepp]

Robert, Thank you very much for your video.Its very understandable.

[@HariniIyerJ]

good explanation on how mapping points describe the graph

[@Spacefish007]

Thanks for that video! It really makes QAM understandable!

[@gokuljith]

Hi Robert, Its very useful video... I got one doubt from 8.07 mins onwards... You say 0 (cos +/-) 0 (cos[same amp]) 0 (sine+/-) 1( sine[diff amp]). In that case LSB 01 should be done with AND operation between 0 (sine+/-) 1( sine[diff amp]), what will be the output ?

[@Gobosarbuel]

hey bro. thanks for your videos they helped me alot (even if i m 26). the thing you said about love in the beginning warmed me up! just because you asked for a comment: 1^2 + 1/2^2 = C^2 (pytagoras) 1+1/4 = C^2 = 4/4 + 1/4 = root(5/4) correct me if i m wrong.

[@jacekpiterow3135]

A script rehearsal done before pressing record button will help to keep steady on the path. Without it video is more dramatic, but harder to follow due to multiple jumps. That it is however, just my perception.

[@WEBBERSPADE]

Hello, I just want to clarify...4 QAM is the same as QPSK. Another example is BPSK which is Binary phase shift keying. Binary meaning only two bits instead of 4. Same theory, more robust, lower bit rate. Thanks for the comment. Robert :-D

[@AlfredoBravo]

Thanks, incredibly easy to understand!!! ;-)

[@hypnotix2000]

Hi Robert, If you can do a video on the transition scheme between each of these QAM symbols, that would be great since that would describe how data would be transmitted in real life. As in the transition from one constellation point to another as it is encapsulated within a notch (which would be a Sinc function in the frequency domain.) - naturally some transitions are easier to implement than others.

[@willcambridge8629]

You're an amazing helpful guy thanks a million

[@kundanprasad1986]

hey...can you please do this video again with a detailed view of 16 and 64 QAM..i am a bit confused...your first part was very good...!! thanks for the first part but please make second part little bit conceptual like what you did in first part....step by step

[@prajanpradhan6089]

Thanks for your video....I really understood what is QAM....:)

[@stephemf]

Hi Robert - great educational videos! Could you try and explain for me how an actual digital signal would get encoded using the 4QAM? You show that there are four 'combined' waves which reach their max amplitudes at the four mapping points - am I right in thinking that these waves are rotating around the polar diagram? How then do they switch between different signal bits? I'm getting mixed up betwen the analogue resultant 'waves' and the digital information... hope you can help! ps keep it up!

[@Gobosarbuel]

yo i just flashed myself into wikipedia a little. they are talking about the "gray-code" its all the same like just that the take sin for x axis and cos for the y axis. damn the more i learn the more i like it. greeting from austria bro

[@abdomoh1870]

thank you very much . your video help me a lot,

[@bhitot1862]

Thanks so much! Great stuff.

[@NghiaTran-fl4qz]

very easy to understand. Thank you a lot.

[@WEBBERSPADE]

Hello ciscotophat, I've spent a bit of time on creating an excel macro that should explain it better, I will make another video to explain it better, in the meantime, you can download it from the link in the description:

[@Eldin873]

thanks man, you are a lifesaver.

[@malvikakamat7233]

hello Robert! I would be grateful if you could also explain DQPSK, pi/4 QPSK and offset QPSK and their differences.

[@z.y.l9242]

I have one doubt that when it came to the end of the video. For 64QAM the contellation diagram would have sixteen point in each qudrant, seems corresponding to 4 amplitude. I think what you wrote is right. I am not sure, just guessing

[@jackotonye]

whats are the differences between QAM and PSK modulation techniques

[@civcinfo]

Thanks so much for your efforts.

[@likenothers]

Thank you very much for this. Very informative!

[@vijojoey7284]

@robert webber thanks for the video... can you please tell me about how these constellation is succesfully decoded at the reciver?

[@TCArcticWolves]

I'll take a guess based on an intro EE class, since no one seems to have answered. To decode amplitude, you can use a combination of low-end and high-end filters to find the voltage you're looking for. Perhaps an analogy is how LEDs turn on only if 3V passes through (they stay off for less than 3). To decode the quadrant, I would guess that one can figure out where the peaks of each wave is based on a timer and where the peaks are (though I'm more inclined to say my guess at the decoding of amplitude is more correct than my guess at the decoding of quadrant).

[@sinsagoodmansbrother]

64 QAM is 6 BITS not 8... 256 QAM is 8 and 1024 QAM is 10 BITS... The Symbol rate times how many BITS per symbol give you the overall Bitrate...

[@hafeezulhassan11]

I would like to ask, you first split the data stream into two parts, one in-phase for cos and other qaudrature sin wave..you encode it using RZ or NRZ or anyother technique and make symbols..SO now, my question is I thnk if you simply change the sign of the cos or sign wave according to 1, 0 bit, and you get a stream as phase jumps due to 1 and 0, and then you add I and Q components you get your modulation.so why you hv to chng amplitude other than +1 or -1?

[@nim7289]

I was also confused as I thought there were 3 amplitudes associated with 16 QAM (although I'm still very new to modulation schemes!) So does root 2 just correspond to the two amplitudes you can give the cos and sine waves you give to the 4th and 2nd bit of one symbol? And by adding these you get 3 amplitudes at the output? Can you explain how the three amplitudes are applied?

[@WEBBERSPADE]

Hello bhaavyang. I am preparing some material. But is there any areas you would like me to explore? It's best to get feedback so I can provide the community what is of better use! Thanks for the comment!

[@bhavyang14]

Robert! It would be really great if you can explain something about the circuitary like how exactly the Modem works and also how different modulation techniques relate to the specral efficiency which is the most crucial aspect in telecommunication. Or I can take little bit of guidance from you about this through email. Whichever is more convinient for you....

[@מרקופילס]

Hi, Very good explanation. I think there is another small mistake at the end. In 64 QAM there are 4 amplitude levels and at 256 QAM ther are 8 amplitudes levels. Please response

[@devilseye2007]

very informative video. thank you .

[@madaresalmotamaizeen998]

when I change sin cos axis in excel I get the same of your chart by using [ cos + 1/2 sin ] is that correct , thanks

[@muebau]

The "?" was not the question. It was just a place holder for "some type of transmission".

[@WEBBERSPADE]

Hello Asraf, in what context are you talking about? Thats a very general question.

[@farhanbadar1716]

Robert why there are two amplitudes for 16 QAM ? I have got root5/2 (twice), root2 (single time), and root2/2 as well. So shouldn't be 3 amplitudes ?

[@nileshparmar2561]

Awesome sir....

[@WEBBERSPADE]

Thanks ;-)

[@DavideBarasti]

Very good job sir

[@bhavyang14]

Robert! Thanks a lot..really nice video, btw do you have part 3 uploaded?

[@ivanfernando89]

Hi Robert, Thank you for this video. It's great. I have a request, could you explain about correlation about QAM, Frequency and Bandwidth ? I am handling a cable modem project. thanks

[@nim7289]

That's excellent, very useful. thanks a lot :D

[@mohabsoft]

thank for the video :) awesome job can you please re-upload the excel file ? thank you

[@asrafmohamedmoubark]

hai there..can u explain to me about qpsk demodulation technique which commonly used? thank you so much.

[@WEBBERSPADE]

THANKS!!

[@horsis21]

Can someone tell me where can i get an example of 64-QAM symbol representation? Kind of confused.

[@farhanbadar1716]

exactly this is what i have obtained out of that. But don't understand that how there are 2 amplitudes, from my calculations there should be 3, i am not sure if I am correct but calculations give three amplitudes.

[@ridoyputrapanjaitan4401]

how about 8-QAM? hoa you make mapping? how could we know that it is a good mapping or not? Thanks a lot

[@sergiosemprebom214]

nao só falo portugues, estou fazendo um trabalho sobre power line comunications para o meu TCC de telecomunicações e tenho que saber sobre modulações qam ofdm e seus processos.

[@poikaa3]

This is two dimensions, what about three?

[@andyserrato]

really good

[@nurainkajola5093]

My lecturer told me 16-QAM has 3 amplitude as against 2 amplitude as you've stated. What do you have to say to this???

[@WEBBERSPADE]

Hello. No I said that you have two choices of amplitude in both axis. So as long as the constallation mapping points (which is normally the case), then yes your lecturer is correct, there are 3 different amplitudes just from the different size of triangles you can make. Does that make sense? Thanks

[@ciscotophat]

I was able to follow up til 8:13 any chance you could explain this out a bit more? Thanks!

[@jalaj2uever]

you are really awesome

[@user-kn7sw7ot9x]

Thanks for the great videos! However, the excel file link is broken...

[@alienaag28]

Hi Robert, thank you very much for take your time and effort to explain this. But guess what, I tried to download the excel but it gives me an Error (404). Could you upload please? Thank you a lot again!!

[@SSGLeader]

How do you add the 2 graphs ? to make 1

[@abdomoh1870]

very nice . i like it , it help me a lot in understanding QAM, I would like you to submit some videos related to the use of QAM And modulation in IEEE802.11Pp or n

[@Gobosarbuel]

and i m afraid to ask but aint there like 3 amplitudes? we got 1x root(2), 2x root(5/4), 1x root(1/2) coming from 1/2^2+1/2^2=C^2

[@divyanshuvarma1043]

thanks sir

[@khalidmohammed2217]

good job

[@nadaali9508]

Thank you

[@GiangLe-rx2sy]

what is 16QAM 2/3 or 16QAM 3/4? help me

[@eheroisme3]

Thanks a lot

[@khansheheyar]

very good lecture the first one but in this one you messed up in the middle. I hope you don't mind. you Better use udemy.com to upload your lecture but not with this camera use some digital whiteboard. Your style of explanation is very good but you need more space to elaborate things in detail. my father is mathematics professor he gave you 10/10 👍

[@935kunalk]

Got it, Thanks :)

[@ing123456]

Anyone get the excel file?

[@crazypaco]

Can you fix the link to excel file ?

[@WEBBERSPADE]

Ola Sergio, farlas espanol?

[@khanhphongtruongpham]

thanks but can u reupload the excel file?

[@FelLoss0]

I'd like to check it out too :(

[@fahd090078601]

could some one help me with the concept of constellation rotation?

[@ShailjaShukla26]

Hey Thanks :)

[@Correder]

mmm... In 16-QAM, there are 4 bits and THREE amplitudes... 0.33V, 0.75V and 1.0V...

[@jianghanxue7351]

yeah feels the same, the peak to peak distance should be evenly divided into 3 normally -3A,-A,A,3A

[@Voodoo444444]

BIUTIFUL ! :_D

[@palashsarate280]

reupload the excel file plz

[@WEBBERSPADE]

Hey, whats up? What don't you get?

[@diwakarprasad1744]

little bit confusing at 9:12

[@madaresalmotamaizeen998]

not as you do in drawing sin + 1/2 cos

[@sergiosemprebom214]

se fosse em portugues

[@Backflipmarine]

files gone

[@eglintonflats]

NOT root 2 but SQUARE ROOT OF 2

[@Jeroenz0r]

okey? :-(

[@StrsAmbrg]

Your hand move too many unnecessary.

[@786Poon]

34 visitors who wanted to know how to learn table of 2

[@thuynguyenthithu4539]

, .

[@Eldin873]

thanks man, you are a lifesaver