What is a Constellation Diagram?

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  • เผยแพร่เมื่อ 28 พ.ย. 2024

ความคิดเห็น • 102

  • @MaxeEricsson
    @MaxeEricsson ปีที่แล้ว +4

    I am a RF Radio System Engineer in Ericsson. I like your radios and thanks for your sharing !!!!! Great explanation for every detailed sub aspects of the whole communication system!

    • @iain_explains
      @iain_explains  ปีที่แล้ว

      Thanks for your nice comment. I'm glad you like the level of detail I put into the videos.

  • @GinMichelangelo
    @GinMichelangelo 2 ปีที่แล้ว +4

    For a non-engineer doing research about 5G and telecom, these videos have been a god-sent. Thank you so very much.

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      That's great to hear. I'm so glad you've found the videos to be helpful.

  • @abusimple1
    @abusimple1 หลายเดือนก่อน

    amazing channel - though complex topics, they are simplified and thorough, just with paper and pencil, no fancy videos. Grateful for your contributions to "real education".

    • @iain_explains
      @iain_explains  28 วันที่ผ่านมา

      I'm so glad you found it useful!

  • @Soho9111
    @Soho9111 2 ปีที่แล้ว +3

    You make the hard stuff that blows our mind off as simple as drinking water
    Thumbs up as usual 👍🏼🫡

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว +1

      That's great to hear. Glad you like the explanations.

  • @stevekim6923
    @stevekim6923 2 ปีที่แล้ว +1

    Your video made me so clear to understand how QAM works! Thank you very much!!!

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      That's great. I'm glad you found the video helpful.

  • @beepbeep8374
    @beepbeep8374 3 ปีที่แล้ว +5

    Thank you, easy and concise, some things I just can’t understand from the textbook

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +1

      Glad you found it helpful.

    • @TheMekkyfly02
      @TheMekkyfly02 3 ปีที่แล้ว

      @@iain_explains 00he 00years were 0in to 00⁰000

  • @exaltant2464
    @exaltant2464 3 ปีที่แล้ว +2

    Great explanation but if you make all the topics and if you order the lectures in a playlist according to any standard textbook(proakis or haykin) it will be really helpful.

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +5

      It sounds like you haven't discovered my web page yet. iaincollings.com

  • @성민욱-y6c
    @성민욱-y6c 5 หลายเดือนก่อน

    Thank you for explaining!
    I have a question in 10:30. My english skill is not good so i don't understand the 'h' and 'root p' in equation.
    Could you tell me more detail about that..?

    • @iain_explains
      @iain_explains  5 หลายเดือนก่อน +1

      The 'h' is the channel gain (which will be a complex number with magnitude between 0 and 1), and the "root p" is the square root of the transmit power.

  • @proton7113
    @proton7113 2 หลายเดือนก่อน

    Thank you for this video. What is the difference between a constellation diagram and an IQ plot? Best

    • @iain_explains
      @iain_explains  2 หลายเดือนก่อน +1

      The Constellation Diagram is plotted on an IQ plot. The output of the demodulator will be a trace on the IQ plot. If you only sample that trace at the symbol times, then you get the output constellation diagram.

  • @maazawan7629
    @maazawan7629 ปีที่แล้ว

    Greetings sir!
    What a wonderful explanation!
    Just curious as to why the normalization factor is square root of average power of all symbols and not just the average power?
    Looking forward

    • @iain_explains
      @iain_explains  ปีที่แล้ว +1

      Power = (voltage)^2 / resistance , and the constellation diagram is essentially showing voltage (normalised for a unit resistor).

  • @tank_tales
    @tank_tales ปีที่แล้ว

    Hungrily waiting for your videos on binary phase shift keying, code division multiple access cdma, binary offset carrier wave modulation

    • @iain_explains
      @iain_explains  ปีที่แล้ว +1

      I've got this video on CDMA: "How does DS CDMA Work?" th-cam.com/video/U_uOrrLBKz4/w-d-xo.html plus others comparing the standards, like this one: "Mobile Standards Evolution: FDMA, TDMA, CDMA, OFDMA" th-cam.com/video/bm53RpK-S2k/w-d-xo.html Have you seen my webpage? I has all the videos listed in categories. iaincollings.com

  • @bobbaberson3654
    @bobbaberson3654 2 ปีที่แล้ว

    I understand why @8:45 the integration is the same for all I but the amplitude is not so clear. For QAM vs 16 QAM would be: (18+18+18+18)=72 vs 4x(2+10+10+18)/16=10. I assumed the amp for QAM is (sqr (3^2+3^2)).

    • @bobbaberson3654
      @bobbaberson3654 2 ปีที่แล้ว

      @Iain Explains Signals, Systems, and Digital Comms it would be great if you take a look at this question.

  • @ΚΩΝΣΤΑΝΤΙΝΟΣΒΛΥΣΝΑΚΗΣ
    @ΚΩΝΣΤΑΝΤΙΝΟΣΒΛΥΣΝΑΚΗΣ 3 ปีที่แล้ว

    Just a correction (If i remeber it correctly!!!). It is φ not Θ since it is phase which in greek is φάση.

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +2

      No, not true. I could have used any symbol I liked. It didn't even need to be a greek letter. I could have made up my own symbol. It is just a label. In any case I think it is better to focus on the content and understanding. That's much more important.

  • @hrachya_khachatryan
    @hrachya_khachatryan 2 ปีที่แล้ว +1

    Hi Iain, thanks for the nice video. One question: Are the carrier frequency fc and the symbol duration time T related to each other? Looking on the plot at 1:11 , I can see that fc equals to 2/T. So I guess in general we can pick fc as an integer multiple of 1/T. But is there any reason for doing so?

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว +1

      In general yes, the maths all works best when we pick fc as an integer multiple of 1/T, but in practice it's not necessary. In passband communications, the carrier frequency is so much higher than the bandwidth, that the fractional extra part of the "final" wavelength in the symbol has negligible effect compared to all the other "whole" wavelengths in the symbol (if you know what I mean).

    • @hrachya_khachatryan
      @hrachya_khachatryan 2 ปีที่แล้ว +1

      @@iain_explains Thanks so much for the answer !

  • @soumyaneogy9522
    @soumyaneogy9522 3 ปีที่แล้ว

    at 10:06 in your video you say "so this gives you a power of 1 " . [1] I did not understand this part . [2] how does that scaling of dividing by square root of average power is making the comparison across different constellation easy ?

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      There is always a limit on the transmit power (due to either government regulations or simple battery limitations in the device). To choose which modulation format to use, we need to make sure they are compared under the same power constraints. It is not acceptable to add more constellation points at the outside of a constellation (ie. to use a higher modulation order, and thus send more data per symbol) without scaling back all the points so that the overall average power remains the same.

  • @Nadine23000
    @Nadine23000 2 ปีที่แล้ว

    Thank you so much mister, easy and clear 🤍🤍👏

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      You are very welcome. I'm glad you liked it.

  • @sumit1412
    @sumit1412 ปีที่แล้ว

    Thank You Iain, for making learning easier :)
    Is this factor 'sqrt(p)' that you have used to normalize the X_k, is the average power of all possible symbols?
    What is it mathematically?

    • @iain_explains
      @iain_explains  ปีที่แล้ว

      Yes, p is the average power. To calculate it, you simply add up the powers of all the symbols and divide by the number of symbols. In the 16-QAM example shown, it is (1^2 + 2*(3^2+1^2)+(3^2+3^2))/4 ... you only need to work out the powers of the 4 symbols in the top right quadrant and divide by 4, since the constellation is symmetric ... and I've just used Pythagoras to calculate the powers of each constellation point.

  • @strategy_TR
    @strategy_TR 10 หลายเดือนก่อน

    sir, can we plot a frequency variation signal's like MFSK using the constellation diagram?
    like making the x axis for 'a' frequency and the y axis for the '2a' frequency ...... and how can we find the absolute value for the vector in this case?

    • @iain_explains
      @iain_explains  10 หลายเดือนก่อน +1

      Yes, that's right. Each symbol (frequency) in FSK is orthogonal to the others, so each constellation point can be represented by a point on an orthogonal vector (in a multi-dimensional space). Then it's just the same as for any other constellation diagram (except in higher dimensions). The decision boundaries are still equidistant between each neighbouring pair of points.

    • @strategy_TR
      @strategy_TR 10 หลายเดือนก่อน +1

      @@iain_explains
      Ok, thank you.

  • @udutiy
    @udutiy 8 หลายเดือนก่อน

    Great job!

    • @iain_explains
      @iain_explains  8 หลายเดือนก่อน

      Thanks. I'm glad you liked the video.

  • @analysislearning9179
    @analysislearning9179 3 ปีที่แล้ว

    Best Explanation Since my graduation.

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      Thanks.

    • @analysislearning9179
      @analysislearning9179 3 ปีที่แล้ว

      @@iain_explains
      Will you be doing any video on Maximum Likelihood Estimation?

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +1

      Have you seen this video on my channel: "What are Maximum Likelihood (ML) and Maximum a posteriori (MAP)?" th-cam.com/video/9Ahdh_8xAEI/w-d-xo.html

    • @analysislearning9179
      @analysislearning9179 3 ปีที่แล้ว +1

      @@iain_explains
      Yes I did. I bookmarked it and liked it too. Thankyou for great work and remarkable presentation style and insights.

  • @mohitkulkarni2183
    @mohitkulkarni2183 2 ปีที่แล้ว

    so can we say The larger the SNR, the more constellation points can be used in a symbol ?

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว +1

      Yes, assuming you're wanting to keep the same bit error rate.

  • @tulsEE87
    @tulsEE87 ปีที่แล้ว

    Sir Thank you for sharing the knowledge. I am from electrical background and I am now exploring digital communication. Can you please explain is it possible to plot constellation diagram for passband communication with out using filters as figure 6.8, page 359 ,fourth edition of Simon Haykin shows that we don't need filter to extract data?

    • @iain_explains
      @iain_explains  ปีที่แล้ว

      I don't have the book handy, but I'm guessing you're referring to a correlation receiver with a mixer and a sampler. That's just a different way to implement the matched filter.

    • @tulsEE87
      @tulsEE87 ปีที่แล้ว +1

      Okay Thank you Sir.@@iain_explains

  • @CSTerminalTech
    @CSTerminalTech 2 ปีที่แล้ว

    The phase at 1:17 is 90 not 0 and at 1:23 it is 270 not 180 . Right?

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      Sorry, but the video is correct. cos(0) = 1. Also cos(2pi f t) is the Real part of e^(j 2pi f t), and so it is along the horizontal axis (theta = 0).

  • @alexsidorkin4871
    @alexsidorkin4871 ปีที่แล้ว

    Good day. I have a remark related to "terminology". Why do you speak about mean power of the costellation when you write the integral. A^2*T = E. It should be mean energy, isn't it?

    • @iain_explains
      @iain_explains  ปีที่แล้ว

      Power and Energy are related by a constant, T (the time duration of the symbol), so it's just a simple scaling between the two.

    • @alexsidorkin4871
      @alexsidorkin4871 ปีที่แล้ว

      For sure. I think wordplay happens because transmitting and receiving constellations should be considered separately and may even have different measured units. What do you think about it?

  • @mehedimanon62
    @mehedimanon62 ปีที่แล้ว

    very helpful sir. Thank you.

  • @hemantsharma2416
    @hemantsharma2416 2 ปีที่แล้ว

    could you please tell me, how the pulse shaping will come into the picture with constellation?

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      If you've seen my video on pulse shaping ("Pulse Shaping and Square Root Raised Cosine" th-cam.com/video/Qe8NQx4ibE8/w-d-xo.html) then you'll know about pulse shaping of a single real-valued data sequence. Then this video on how to send complex baseband signals will show you how to extend to the complex-valued data sequence case: "How are Complex Baseband Digital Signals Transmitted?" th-cam.com/video/0lkRJgnywkg/w-d-xo.html

  • @63maurizios
    @63maurizios 3 ปีที่แล้ว

    I am bit confused in the part where average power is defined (around time 8:00). If value is integrated over time would not be an average energy (at least dimensionally)?

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      The term "average power" means "averaged over the different possible constellation points (transmission signals)" assuming that the data is equally likely 1's and 0's (ie. assuming that each constellation point is equally likely.)

    • @63maurizios
      @63maurizios 3 ปีที่แล้ว

      @@iain_explains thanks for the reply but my doubt is not about the fact that we are "averaging" but rather on the quantity we are averaging. I see we are integrating over given time (the period) the square of signal value; so it looks to me we are averaging an energy rather than power. Could you please clarify to me this point? Thanks

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      Ah, sorry, I see now. Yes, I should have called it energy (sorry about that). It's just a scaling of T between the two, so sometimes the final equation is written with P's (Power) and sometimes with E's (Energy). Depending on which is put there, the variance of the noise term n_k is either N_0 (for the Power version) or N_0W (for the energy version). This video has more details: "What are SNR and Eb/No?" th-cam.com/video/bNYvXr6tzXQ/w-d-xo.html

  • @zewei98
    @zewei98 3 ปีที่แล้ว

    Very clear explanation, thank you so much!!!

  • @rishabhkumar1050
    @rishabhkumar1050 2 ปีที่แล้ว

    sir can you please tell me the difference between the average power and transmitted power i mean i am not able to figure out the difference , are they same?
    and secondly @10:07 what do you mean by unity power (Xk/sqrt(p'))= 1?

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว +2

      "Transmitted power" is the power at the output of the transmit amplifier that is connected to the UTP/Coax cable (for wireline channels), or as it goes into the antenna (for wireless), or laser (for optical channels). Typically the "average" value is quoted. "Instantaneous power" goes up and down at the carrier frequency, since it is defined as being the square of the voltage. If you want to compare two different modulation formats, you need to make sure you are doing a fair comparison, and so you scale the constellations (ie. the actual transmit waveforms) so that they have the same average power. The clearest way is to scale them to unity (ie. so the power equals 1).

    • @rishabhkumar1050
      @rishabhkumar1050 2 ปีที่แล้ว +1

      @@iain_explains ok I got it now thankyou sir for looking into it

  • @aarzoosingh8316
    @aarzoosingh8316 2 ปีที่แล้ว

    sir @ 7:04 whether it would be energy as we are transmitting the signal for only Tb duration and signal which we are sending is energy signal i think ??
    anyhow a great video sir now i can visualize the waveforms thanks for this

    • @iain_explains
      @iain_explains  2 ปีที่แล้ว

      Sorry, I'm not sure what you mean by "energy signal". But in any case, I'm glad you found the video helpful.

  • @himanshukumarshekhar2711
    @himanshukumarshekhar2711 3 ปีที่แล้ว

    Sir, nice video, sir I have one doubt, constellation diagrams is used to demodulate the symbol?

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +2

      The constellation diagram is used to visualise all the symbols. It shows where the decision boundaries could be placed in a demodulator to decide which symbol was sent.

  • @sagarrawat7203
    @sagarrawat7203 8 หลายเดือนก่อน

    I have doubt in constellation points. How it works?

    • @iain_explains
      @iain_explains  8 หลายเดือนก่อน

      See: "What is a Constellation Diagram?" th-cam.com/video/kfJeL4LQ43s/w-d-xo.html

    • @sagarrawat7203
      @sagarrawat7203 8 หลายเดือนก่อน +1

      @@iain_explains ❤️ got it sir

  • @puffio3773
    @puffio3773 3 ปีที่แล้ว +1

    thank u sir

  • @ilyavladimirov152
    @ilyavladimirov152 3 ปีที่แล้ว

    Thanks! You are making a good video. And good explain and make complex things simple, accessible and understandable. It would be nice if there was a video about EVM and MER. And about the influence of various factors on the EVM (for example phase noise)

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +2

      Thank s, I'm glad you like the videos. And thanks for the topic suggestions, I've added them to my "to do" list.

  • @bijoyroychowdhuryprinon6768
    @bijoyroychowdhuryprinon6768 2 ปีที่แล้ว

    great video..appreciated..

  • @demetriusdemarcusbartholom8063
    @demetriusdemarcusbartholom8063 2 ปีที่แล้ว

    ECE 485, UofA.

  • @longpham4205
    @longpham4205 3 ปีที่แล้ว

    Thank you sir! I was reading that book of Goldsmith and felt like it was written in alien's language. You save me!

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      I'm glad the video helped. Have you seen my webpage with a full categorised listing of all the topics? iaincollings.com

  • @tuongnguyen9391
    @tuongnguyen9391 3 ปีที่แล้ว

    Thank you !

  • @arafathabib4020
    @arafathabib4020 3 ปีที่แล้ว

    Thank youuuu sooo much professor. Love you.

  • @amdPeek
    @amdPeek 3 ปีที่แล้ว

    damn finally a useful video, thanks !

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว

      Glad you found it helpful. If you're looking for other useful videos, you might like the others on my channel. You can find a categorised list here: iaincollings.com

  • @vishalmishra7568
    @vishalmishra7568 3 ปีที่แล้ว +1

    Hello Sir, Please make a video on OQPSK and MSK !!

    • @iain_explains
      @iain_explains  3 ปีที่แล้ว +1

      Thanks for the suggestion, I've added them to my "to do" list.

  • @merabeautiful-qc5on
    @merabeautiful-qc5on หลายเดือนก่อน

    v smart

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    @90k13xx 3 ปีที่แล้ว

    I’m in 5th learning Algebra :(

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    Swaniawski Springs

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    @SamSabrina-w3p 2 หลายเดือนก่อน

    Dayne Stream

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    @Zachsnotboard ปีที่แล้ว

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