i start with nothing ,ends with how signal spreading works.thank u again

It takes a smart person to explain a complicated thing in a complicated way, but it takes a real genius to explain a complicated thing in a simple way. Thanks for sharing, and great video!

To everyone using 1 = +1V and 0 = -1V, use logical XNOR not XOR. Logical XNOR is: if bits are same output = 1, if not output = 0. Example of XNOR logic 1010 0000 0011 1101 =0110 0010

"tshuid, tshuid, tshuid.." waveforms

This is brilliant, love the sounds effects. You can really tell you enjoy teaching people

Looking forward for more videos. It was so easy to understand, every step was crystal clear, superbly explained.

you forgot to mention that the codes of other users should be orthorgonal to each other, which is why they don't come up (=zero) at integration aka decoding.

This is such a good video! I didn't know what I was doing until I watched your video!!!

Fascinating. Glad to finally get a basic understanding of this concept instead of being shoved a million acronyms to memorize. (Looking at you, CompTIA!)

Really well-explained and clear. Thanks a lot!

Two codes are said to be orthogonal if when they are multiplied together the result is added over a period of time they sum to zero. For example a codes 1 -1 -1 1 and 1 -1 1 -1 when multiplied together give 1 1 -1 -1 which gives the sum zero. An example of an orthogonal code set is the Walsh codes

Amazingly well explained. Thanks for your effort.

You have no idea how you just save my life!

Wow! That is what people need. This is called "explaining"! Thank you!

This kind of explanations are genuinely fantastic. CDMA, OFDM, and all digital modern signal processing are a sort of magic. the video is simple and effective straight to the point fot an initial understanding. Everyone aged remember the landline equipment to transfer data through a physical line up to 64kbps(if good cabling was fitted at home). At some point xDSL lines and clever modulation techniques arrived and now on the same cable you can transfer dozen of megabits, maybe 100mbit without to change the cabling at home. At some point the miniaturized electronics gone further and the WiFi in a similar manner skyrocketed the capability to provide network connections at cheap price.

Thank you so much for the demonstration. I have struggled with CDM, but not anymore :D

Man you are my hero.God Bless you!!!

Amazing CDMA, amazing explanation, amazing video! Thanks!

Finally understood this subject! Many thanks!

Thank you, I came here to find out what a "chip" was and you showed me. Cool exercise.

Best video out there for this topic! Thank you. Legendary.

best explanation in the whole youtube and i love ur waveforms ishukk ishukk sounds

An excellent video. I have seen very mathematical explanation of this simple beautiful theory that makes you go nuts. This is so wonderful an explanation. Good Luck.

such a great person you are,a follower from IRAQ

Thanks For This. Been Really looking for a good detailed video!! Thumbs Up!!

I don't know how often you check the comments but this was terrific! I needed to understand this for a blog I am writing and I can completely get it now. :-) Thank you so much!!

This helped me understand CDMA so much more! Thanks for posting!

FN brilliant explanation and presentation! Thank you so much

Good stuff Carl. Easy to understand. thanks

Its explained in very simple manner !! I liked it !

You nailed it man

I used to work on a CDMA2000 Rev. A network. Nicely done!

Thanks very much Carl you helped me unbend my mind. Watch it all the way through before you thumbs down folks.

thank you, you saved me a lot of time. hope to complete the way for ofdma. thanks a lot

VERY THANKS.for helped me to study cdma technology...for my university exams

Very good explanation!

loved it tomorrow is my midterm this helped me allot.

Thank you very much Sir..!

Good Job, pretty well explained! Thanks.

Very good example. Thanks.

It is really great ! Thank you !

Excellent! I would add some discussion on the need for codes to be "orthogonal" and the way to generate codes

Very good explanation, great video

nicely explained Oliver!

extremely useful video, thanks Sir!

thnku so much......its very easy to understand the concept

Great explanation. Thanks!

what a magical stuff !!! i adore it :).

Thank you for making it so simple

Great video, thanks!

Very very very clear. Thank you!

thanks a lot Mr Oliver! It helped me so much ;)

very detailed and clear explanation

good video!! tanks for explain CDMA Signal Spreading

Carl Oliver Im confused when do we use the XOR operation vs the AND( same bit output =1) operation.

Awesome explanation

Thank you! It's clear!

Perfectly done. Thanks

good video for signal spreading, thanks.

very useful for me to understand

thanks sir its really useful.....

amazing explanation!

Thank you my teacher after now i give respect

thanks for the explain!

🎉 extremely good explanation

Wow, very clear. Thanks a lot

Nice one man!! Thank you

Explaining it in such a simple way, absolutely useful. But just think about whoever came up with this idea the first in the last cubical at Qualcomm offices.

Thank it's really a good explanation

Very useful and clear explanation! Thanks a lot! Since the example you gave is synchronous, how to decode the asynchronous signals mixed up by different users?

Very helpful. Thank you.

Super sir. Very good explanation

This is a very cool video. At the same time, if you just use -1 instead of 0, then you don't have to go through the awkward numerical manipulations of saying 0= +1 V and 1= -1 V. You can just say -1 = -1 V and 1 = +1 V. At least, it seems to work out that way if I haven't blundered in my calculations (always a possibility). Is there any particular reason to go through the artificial manipulations when it seems like there is a straight-forward way to do it?

What are the different codes (other than Walsh codes) which can be used for this type of coding at transmitting end. The procedure of analysis(like the one which you have shown in your video), if we use a different coding scheme, will remain same or vary from code to code?

+Carl Oliver when you are using -1V as 1 bit and +1V as 0 bit your spread massage sm = code XOR data, but when you are using -1V as 0 and +1V as 1 your spread massage should be sm = code XNOR data. That way all problems with switching bits voltage are gone. Am I right?

Great Sir.Thanks

How does uplink works in CDMA? Does 3 transmitters of their chips naturally mixed over the air to the combined signal?

I like the color of your pen, makes me feel like i have wasted my life.

Thanks for the good video. Here is a question: Why do we use the MULTIPLICATION (and not another mathematical or logical operation) of the composite signal and the code of the n-th user?

Wow excellent lecture

Mercii Oliver , it was so helpful

I expect more videos regarding wireless communications n related technologies... I have subscribed to ur channel

When working this out in google sheets, my user 2 comes out as "-0.25, 0", and my user3 data comes out as "-0.25, 0.25". Why is it +/- 0.25 instead of +/-1? Is it presumed in decoding that if it's a non-zero result, then it is a 1 result (there for -0.25 or +0.25 is converted to 1)?

Excellent video

Suppose User-1 wants to transmit his message to a user [say user-k]. Then to decode the transmitted message, user-k will be required the signature code i.e. pn-sequence or spreading code of user-1. How will he get that?

I am going to pass my exam because of you. thank you so much

great explanation

can four users can send the data and receive the same waveforms at the end

How does the interleaving of messages from different users in CDMA is done?

Awesome explanation especially the last part which ties it together - that really demonstrates "orthogonality"... So now, can someone, anyone, add to this the Public Long Code Mask (Long PN Code) as well as the PN Offset (Short PN Code), and talk about how CDMA 2000 uses 3 codes simultaneous to achieve channel access? How do the PN Codes work, and how do they prevent them from interfering with the Walsh Code process?

how would one emit a signal with +1 or -1 volt? would it simply be more amplitude or less amplitude of the wave? That's the only part I'm not following.

Thank you this definitely cleared up confusion. I have some questions though. Does CDMA rely on the fact that the spreading codes do not interfere? I assume you can't just choose any spreading code for each user. How does CDMA account for power loss of an EM signal over the air? Amplitude decreases has the distance a signal travels increases. So +2V, +3V may look like +1V, +1.5V for someone far away. How do they account for that?

thankx man ur a legend

Beautiful. Lovely.

you are wonderful thanks alot carl :*

Absolute legend!

Handsome and inteligent i love this man

I was trying to use this method for my assignment but it doesn't work for 0 bit =-1volt and bit 1 =+1 volt

COOL！！！！！！！！！！！！！Thank you !!! The video helped me a lot!!!!!!!!

Excellent! Thanks!!