Inside Wireless: QAM modulation II - The Modulator
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- เผยแพร่เมื่อ 26 มิ.ย. 2024
- QAM modulation is vital to most of modern digital RF radios out there. But what exactly the modulator does? We explain in this episode of Inside Wireless! Learn more: rfelements.com/
Modulation is a process of encoding the digital data - 1 and 0s - onto an RF wave that is more suitable for wireless transmission. The QAM modulator is the circuit inside the radio that takes care of this.
If not sure about the basics of QAM modulation, check our previous video: • Inside Wireless: QAM m...
The basic idea is that the incoming data stream is divided into two branches. The length of the 'symbol', or, the amount of 1s and 0s processed in parallel determines the depth of the modulation. The higher the number, the more data we transfer during one transmission.
The RF carrier signal is brought to both of these branches and multiplied by the amplitude (strength) determined by the input data stream. One branch is called I (in-phase) and the other Q (quadrature). The quadrature means that the I and Q waves are shifted by 90 degrees with respect to each other. After that, the I and Q signals are added to produce the output RF signal.
The increasing data density with growing length of the input symbol is easily seen on an IQ diagram showing each unique symbol the modulator can produce. The higher the data density in the same space, the higher the SNR of the signal needed for successful data transfer - check out this video for detailed explanation: • Inside Wireless: Noise...
Spectral efficiency is a measure of increasing data transfer efficiency with growing QAM depth.
The distances at which the typical WISP radio is capable of working at highest MCS rates are very short - this is again connected to the SNR requirement of the signal and the output amplifier linearity - check our video on this topic: • Inside Wireless: MCS i...
00:00 - Intro
00:42 - QPSK / 4 QAM
01:41 - Constellation diagram
02:26 - 16 QAM - 1024 QAM
03:35 - Spectral Efficiency
04:46 - RF noise challenge
#RFelements #InsideWireless #QAM #QAMmodulation #QuadratureAmplitudeModulation #QAMmodulator #Antennas #AntennaTheory #WISP #SaveSpectrum #RejectNoise #growsmart #UbiquitiNetworks #CambiumNetworks #MimosaNetworks #Mikrotik - วิทยาศาสตร์และเทคโนโลยี
How far would you say can QAM go? 2048, 4096... even further? 🤔
Hi, I like your videos and it is very informative. Are you from Sweden?
@@kazievan Thanks, we are from Slovakia :)
commercial deployment actually : 16384
Excellent video. I was a cable guy about a decade ago. Finally finishing up my electrical engineering degree next year. This makes so much more sense now when I was looking at constellation diagrams on my cable meter many years ago. I just knew that sharper meant better lol
Very clear explanation, thanks a lot
Thank you so much guys. In 10 minutes with you I understood crucial part of my studies
Damn bro , this video was excellent man. Ive not seen the concept of IQ explained better anywhere else on the net so far. Thanks a lot you guys!!
Thank you! We are happy the videos are useful.
Very useful video, thank you so much
That was a great explanation!!! Keep up the great work! I've learned so much from these videos.
We are very happy about that! That is the idea of the whole series!
very clear, and easy to understand, thanks a lot
Amazing illustration..hats off
Great Work! Thank you Guys!
Great video, making everything so simple and interesting. Keep on and do more great tut .
Thank you, we will do our best to keep it up!
This is a good explanation and reference to those who still launching 4G and 5G sites with 30m height. For getting huger MCS and Modulation antennas should be very close to subscribers. I think 15 meter height is more than enough for 5G 3500mhz (sub-6) and without obstacles between antenna and user. Thanks for sharing your knowledge
Great work and explanation, thanks a lot; best Inside Wireless content in the world.
Very flattering, 😊 thank you, we are glad the videos do good for people out there!
Hi there, Your videos are really nice bro., they are short,informative,easy to understand and with very useful and conceptual animations......
Thank you these videos are great!
Glad you like them!
amazing explanation ! thank you
Awesome video
Thanks for this great explanation of the basics, very helpful.I come from in Viet Nam
Greetings to Viet Nam, Phan.
Thanks a lot!
VERY good video
Very interesting video
My man!!! You should be a teacher :-) Awesome explanation
Thanks! 😃
Shrt and crisp👌
Thank you for an excellent video explaining this so clearly. I would only add that I believe SNR is signal power divided by noise power, not minus it, hence why it's called a ratio.
You're welcome! Good catch by the way - it is not stated explicitly, but of course we assumed the log scale, so division in linear is subtraction in logarithmic..
@@Rfelements Ah I see! I don't work with RF so didn't realise that log scale typically used, thanks
well done
so usefull thank you
Спасибо!
now the IW videos have Russian subtitles as well, feel free to share with your friends / colleagues..
🤍💙💔
just wow
After the bit and carrier goes through the product modulator, what do you get? Is the carrier's phase and amplitude changed? If so how does it happen
Un transistor npn con be y bc modula por así decir los impulsos acelerados y concomunitantes en la antena 2d
I am a bit confused about something: It seems that in many diagrams out there, the incoming bitstreams into the mixers are labeled as I and Q, as if this digital data was in quadrature before getting applied to the mixer. However, based on this video, it looks like the data is not actually in quadrature until it mixes with the carriers which is in quadrature, since the 2 sinusoids are 90 degrees appart. So my question is the following: is the incoming bitstream in quadrature already? and if it is, is this a must?
The bit stream at the entrance to the modulator is not in quadrature, you got it right, it's the two sin waves that are in quadrature..
Should the position of the 10 and 11 be switched on the QPSK constellation diagram at 2:16?
Hello!. It should not, is the correct way. You start counterclockwise and add +1 in each sector. Results are shown in binary. Thanks
Thanks for the reply:)
So if the i and q amplitudes are both 1 then does it make a 45 degree angle with the x axis? If so then shouldn't this position correspond to the value 11? Based on the previous animation that showed 1s corresponding to an amplitude of 1 and 0s corresponding to an amplitude of -1.
how to about RF elements cosider making 11 Ghz antennas ?
Maybe in the future, for now we focus on lower frequencies though..
Comment for the algorithm
🌹🌹🌹
Constellation plot is like a kmap sorta
what K map do you mean?
Great video 👍...but, how can QPSK be the same as 4QAM? After all, QPSK has no modulation of the amplitude. There is only one possible level of the amplitude, and the symbols are determined only by the phase shift, unlike for example 16QAM which has three levels of the amplitude (hence the name AM), in addition to the phase shift. Doesn't this mean that 4QAM must have two levels of amplitude, and only two levels of phase?
Hello!. Unfortunately, it doesn't mean that. To have two amplitudes you will need to have them in the constellation diagram (lets say the X axis), and then one of them will be the strongest. In the constellation diagram we show here, which is the one used in 5GHz wireless networks, all the symbols are equally strongest when compared from the center. Also, when you search QPSK and 4QAM you get the same result (neither of them is much used as well). Thanks
So it’s likely not worth paying more for a 1024 qam router vs 256 qam?
router is one of the many devices in the chain... it depends if you have customers willing to pay for higher speeds, and if the hardware you use lets you leverage the high QAM rates..
@@Rfelements thanks. I ask because I purchased Costco’s Netgear RAXE450 wifi 6e router which has 256 QAM which is different then Netgear’s RAXE500 wifi 6e router that does have 1024 QAM.
It was $100 cheaper.
I was thinking of returning it to get the full benefits of wifi 6 and future proof with 6 gh band. Thanks
Thanks for responding. Correct the bandwidth is a bit lower, however does having only 256 qam still make the raxe450 a wifi 6 router? It is advertised as such but with 256 qam. Thanks again.
@@davidbosshart4448 The product spec says it supports 802.11ax, which is marketed as wifi 6.
These guys should start an educational institution
sounds cool, too technical for me
which part did you not understand? Maybe we can explain better..
I don’t think it’s real… I see Imaginary numbers all over… it’s complex…
No real math in this explaination. No meat
This guy just can’t make the TH sound. “Da, udder, dis…” the, other, this.