How LoRa Modulation really works - long range communication using chirps

Ғылым және технология

LoRa (LoRaWAN) is a new modulation technique optimised for long range, low power, low bitrate communication. You'll often hear people say LoRa uses "Chirp Spread Spectrum', but this alone is only a small part of the story. LoRa uses an elegant mathematical trick to allow more efficient receivers. In this video, I outline how LoRa modulation works - it is incredibly unique. I was amazed how LoRa can communicate well beneath the noise floor. I tested the performance of LoRa with a Matlab livescript demonstration.
00:00 Introduction
01:00 Chirps as the basis for LoRa
04:20 Towards a mathematical description of the LoRa symbol
09:00 Correlation
12:34 Our first attempt at a receiver
13:12 Towards a more efficient receiver using a "mathematical trick"
16:40 Performance of LoRa
18:54 Matlab code to simulate a LoRa system
26:32 Summary

Пікірлер: 291

  • @VisualElectric_
    @VisualElectric_ Жыл бұрын

    Which modulation scheme should I cover next? 🤔

  • @zachreyhelmberger894

    @zachreyhelmberger894

    6 ай бұрын

    I thought FT8, JT65, JT9, etc, were the best low noise schemes because of the very narrow bandwidth, which means you can use very narrow filters and get rid of almost all the noise.

  • @tomaszsalwach8423

    @tomaszsalwach8423

    6 ай бұрын

    This one....but after reading what Shannon limit is and Eb/N0... Then you will compare apple to apples....

  • @thesolderman861

    @thesolderman861

    5 ай бұрын

    GPS Signals also come below the noise floor. They also have a correlation receiver type. The descriptions of it, that I found, did not brought me insight how it really works on the modulation level. I only understood that upper layer, there it receives from the 4 or more satellites their precise realtime and precise in space position, albeit the last digits of these numbers are enciphered for intentionally reducing the precision on non-military receivers.

  • @JxH

    @JxH

    5 ай бұрын

    I agree with Zach..894, any of the digital modes created by Dr. Joe Taylor. Use FT8 as your search term.

  • @marcin_szczurowski

    @marcin_szczurowski

    4 ай бұрын

    Go for WCDMA so you can compare processing gain against LoRa.

  • @AdarshMammen3
    @AdarshMammen32 жыл бұрын

    This is possibly the best explanation of Lora modulation I’ve seen ever…

  • @mhr4778

    @mhr4778

    Жыл бұрын

    It's like all of signal processing topics in one video! Exciting to learn about a robust platform with so much room for a lot of creative micro modulations.

  • @imlassuom

    @imlassuom

    Жыл бұрын

    No it is not !!

  • @bjorn2625

    @bjorn2625

    6 ай бұрын

    @@imlassuomcould you link to a better one? I’d love to see that one too.

  • @eswnl1

    @eswnl1

    5 ай бұрын

    Why?

  • @RobFisherUK

    @RobFisherUK

    Ай бұрын

    This is possibly the best explanation of anything I've ever seen.

  • @paaao
    @paaao Жыл бұрын

    I’m a ham operator. I setup a LoRa base station using the lora ham shield that runs on top of an arduino. With that arduino plugged into my raspberry pi at home, and another arduino with lora hsm shield running in my car. I was able to TX/RX short text messages first try back/forth about 9 miles apart. This was at only 1 watt or less power output, on 440 mhz. I was dumbfounded. It took some pass band filters, and good antennas, but still… Able to communicate well beyond any voice, digital voice, or digital modes on UHF from a very tough location to another, separated by multiple freeways, high rise buildings, trees, cars, etc, etc…

  • @brianbutton6346

    @brianbutton6346

    3 ай бұрын

    That is impressive.

  • @paddler-sn7ub

    @paddler-sn7ub

    3 ай бұрын

    Have a tutorial? I would be interested in your project 👍🏽

  • @paaao

    @paaao

    3 ай бұрын

    @paddler-sn7ub I don't sorry. It was an old project based on the LoRaChat program, and lora hamshield. The youtube channel was run by username inductive twig or something, and the arduino code for LoRaChat is on his github page. The key to making these cheap single board transceivers communicate much further than what is possible, is by using band pass filters to block out all the other RF noise. So I used very tight, 435 to 450 mhz band pass filters when experimenting. Also very good coax and antennas. My base station during that test had 1/2" hardline running up to a good folded dipole 15' above my roof. So just reducing the losses. Especially at the receive side.

  • @w5cdt
    @w5cdt4 ай бұрын

    “You can always detect a sine wave in noise….if you are willing to “wait” long enough” - E.J. Swanson

  • @777arc2
    @777arc2 Жыл бұрын

    This wasn't really emphasized but usually more bits per symbol means worse performance for a given SNR, but in LoRas case, a higher SF also greatly increases the symbol's duration (as well as the bits per symbol), increasing SF by 1 means 1 more bit per symbol but it also doubles the symbol length, so that gives you more effective spreading, and lets you go to lower SNRs.

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Yes, you explain it well.

  • @flapjack9495

    @flapjack9495

    Жыл бұрын

    I was confused by this at first because I'm so used to more bits per symbol meaning worse performance, but this makes it clear, thanks!

  • @gauthierostervall4849

    @gauthierostervall4849

    10 ай бұрын

    Thanks for adding this crucial comment. I'm not sure why longer symbols give more effective spreading?

  • @oceanexplorationlab

    @oceanexplorationlab

    8 ай бұрын

    This is an extremely important point that confused me at first. Since the symbol duration doubles with each increase in the spreading factor by one, the symbol duration increases exponentially with the SF. However, the number of bits per symbol increases linearly with the SF. Consequently, the overall data rate decreases with an increased SF. There's no magic there; a lower data rate improves the permissible signal-to-noise ratio.

  • @1isten2me

    @1isten2me

    6 ай бұрын

    So how does the performance versus the bit energy to noise density ratio (Eb/No) compare to other modulation schemes and how does it change with SF?

  • @carlosaldea
    @carlosaldea Жыл бұрын

    It absolutely blew my mind how clearly you have explained the LoRa modulation despite the complex maths behind it.

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Thanks!

  • @edinfific2576
    @edinfific2576 Жыл бұрын

    This is what I call well-balanced video making and editing: normal transitions, clear presentation, voice level fairly constant, background tune merely present and allows or even helps one to get immersed in the topic without being disturbed either by its loudness or a crappy tune choice. Your explanation is pretty good and shows you have a good understanding of the principles, but math is my weak side so I mostly skip over calculus and differential equations.

  • @gblargg

    @gblargg

    5 ай бұрын

    If he'd encoded the music using LoRa it could have been turned down to below the noise floor! /s

  • @pedrovictorc
    @pedrovictorcАй бұрын

    Man, your explanation is awesome. I really liked the way you added the paper information and brought a nice explanation. Please, keep going with these kind of videos. Regards, Pedro.

  • @satviksharma3722
    @satviksharma37222 жыл бұрын

    Dont know what amazed me more - the LoRa protocol or your explaination. Thanks for the video.

  • @hariwi39
    @hariwi399 күн бұрын

    I have been long time to browse such best explanation of Lora to understand, thanks for great lecture

  • @educationshouldbefun3
    @educationshouldbefun32 жыл бұрын

    Great video! Just one comment: The LoRa demodulator is basically a correlator plus a bank of filters, the latter being implemented using FFT. And, the LoRa symbols are basically time shifted versions of each other. Conceptually it is very similar to an FMCW radar that also uses a similar demodulator. Instead of the symbols, the radar receives time delayed versions of the chirp waveform depending on the location of the target. The correlator output is a sine wave (for a single point target) whose frequency is proportional to the time delay (i.e. the range). Bank of filters (i.e. FFT) can thus be used to discriminate targets.

  • @eswnl1

    @eswnl1

    4 ай бұрын

    Are matched filters used to sense each frequency component?

  • @senfilatechnologies2938

    @senfilatechnologies2938

    4 ай бұрын

    The FFT by its nature is a matched filter to the fundamental sin/cos waves@@eswnl1

  • @standriggs2420

    @standriggs2420

    3 ай бұрын

    @@eswnl1 The FFT IS the bank of matched filters. Each FFT bin is computing how well the input signal matches the frequency for that bin. For CSS, the highest bin number is the symbol. For FMCW radar, the highest bin number is the range.

  • @travnewmatic
    @travnewmatic2 ай бұрын

    Perfect material for our LoRa APRS group!

  • @martinmckee5333
    @martinmckee53332 жыл бұрын

    I've been very impressed with the performance I've been getting with LoRa, and this was a wonderful addition to the documentation from Semtec. They make it easy enough to use, but this understanding is invaluable.

  • @user-qp2ps1bk3b
    @user-qp2ps1bk3b15 күн бұрын

    thank you so much, kind person! Without you it would have taken ages for to learn all of that

  • @hradynarski
    @hradynarski Жыл бұрын

    I'm new to radio staff. But I have basic knowledge of signal processing from my university studied 30 years ago. That is best described LoRa that I really understood. Keep up with a great job spreading knowledge and understanding!!! 🙏🙏🙏

  • @charliesoffer
    @charliesoffer22 күн бұрын

    Great tutorial! KZread at it's finest. Thank you.

  • @elguapo3436
    @elguapo34364 ай бұрын

    This the very original way in which knowledge should be conveyed. Structured, well articulated language and definitely accurate. Thank you for your time and effort. New subscriber.

  • @mateussertanejo2009
    @mateussertanejo20092 жыл бұрын

    Wonderful video. Amazing. I'm working with LoRA modeling on my thesis. Great job and great explanation.

  • @itskevscott
    @itskevscott11 ай бұрын

    Excellent video mate, cheers for that! Good to see matlab getting used as well, it is invaluable in so many ways.

  • @TheMomo2212
    @TheMomo22126 ай бұрын

    Truly wonderful and comprehensive explanation. Thanks a lot!

  • @LittleScientist2011
    @LittleScientist20112 жыл бұрын

    Brilliant video, this has demystified how the modulation and below noise floor parts work for me far better than any other video I've watched.

  • @davidwilkie9551
    @davidwilkie95515 ай бұрын

    Life, the Universe and Everything. Excellent Teaching.

  • @bonowong3524
    @bonowong3524 Жыл бұрын

    What a great video and details explanation! That helps me a lot with my project in LoRa IoT! Thank you very much!

  • @mikegofton1
    @mikegofton12 жыл бұрын

    Thanks for such a well presented and clear description of the modulation scheme used. In response to your question, the LoRa modulation scheme is still subject to the Shannon limit, the maximum information rate is a function of channel SNR and bandwidth. If you increase the spreading factor in a channel where the SNR is constant, you will need more bandwidth to maintain the received symbol error rate. As bandwidth is usually fixed for a given channel, the SF can be varied to optimise information throughput for a given channel SNR. This can be done adaptively as the SNR varies over time, due to radio fading and interference sources.

  • @rockapedra1130
    @rockapedra11305 ай бұрын

    This is a super valuable video! Simple and to the point. Thanks!

  • @kuravasic
    @kuravasic Жыл бұрын

    This video is simply unbelievable, very clever explanation!

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Thanks!

  • @secondarycontainment4727
    @secondarycontainment47276 ай бұрын

    As a visual learner - THANK YOU! I don't think I could have ever wrapped my head around this without your visual representation of time. All of it makes sense and, when you see how it works, it is one of those things that makes you go - yeah, why did it take so long for this to be figured out?! THANK YOU!!!

  • @highfidelityinc
    @highfidelityinc Жыл бұрын

    Many thanks for posting this video. I had no idea how LoRa worked beforehand but your video clearly explained it. It took a while to figure out how convert your Matlab code into Octave code and correct my typos. But the final result worked exactly like your demo showed.

  • @mikemccauley2

    @mikemccauley2

    4 ай бұрын

    Can you pls share your octave version?

  • @zerodegrekelvin2
    @zerodegrekelvin2 Жыл бұрын

    This is a really good video you did explaining LoRa "mathematics', i.e. the magic of decoding a symbol where signal is less than noise i.e. SNR negative 8-) and the Matlab code is really useful. Thank you!

  • @sureshchandrachauhan8167
    @sureshchandrachauhan81672 жыл бұрын

    Excellent explanation. Excellent content. Excellent topic. Keep up the good work.

  • @alexmassy
    @alexmassy Жыл бұрын

    Excellent ! Really helped me to grasp the intution about LoRa !

  • @lavanyaraman7999
    @lavanyaraman79992 ай бұрын

    Truly amazing work . Thanks for your efforts. Inspiring ❤

  • @andriypostelzhuk9655
    @andriypostelzhuk96558 ай бұрын

    This video really explains not only LoRa protocol. But Modulation/Demodulation process in general. Nice!

  • @japaz0r
    @japaz0r4 ай бұрын

    Incredible explanation! Thanks!

  • @VincentFischer
    @VincentFischer Жыл бұрын

    Thanks for explaining this what I always considered RF wizardry. Even though I don't have the mathematical fundament to stand on to understand it thoroughly, I have the feeling that I'm a lot smarter than before the video

  • @xatteg
    @xatteg9 ай бұрын

    Great Vid! Although I mostly forgot university maths, I got to understand the principle of spreading factor and symbols on LORA.

  • @ZeR0God
    @ZeR0God5 ай бұрын

    Signed up! Love so deep math analysis.

  • @sebastianbabiel6155
    @sebastianbabiel6155 Жыл бұрын

    Really good explanation! Again this shows the power of FFT. OFDM uses a similar mathimatical trick with the FFT btw.

  • @raymondbyczko
    @raymondbyczko6 ай бұрын

    Well produced! I'll investigate more with MatLab; very inspiring!

  • @herman7140
    @herman7140 Жыл бұрын

    Brilliant explanation. Thank you

  • @peterderidder6549
    @peterderidder6549 Жыл бұрын

    Well done. It would be interesting to add information about the bandwidth of the signal vs SF. This relates directly to the received noise and hence the S/N ratio. This will perhaps also shed a light on your question how far one can go by increasing the SF.

  • @johnwest7993
    @johnwest79934 ай бұрын

    I have only a high-school education. a total of 13 years of formal education, and no math beyond a semester of intro to algebra, but my fascination with RF led me to do a bit of research, and I ended up building a LowFER antenna and transmitter (175 kHz) transmitting BPSK ASCII using a computer program called Coherent, and with my transmitting beacon sending a short, repetitive text message, using crystal ovens at the beacon and in a homebrew receiver in my car, and averaging out the noise I was able to receive my beacon's text message, ( except for a couple of minutes in De Moines, Iowa, every foot of the way as I drove over a distance of 800 miles. It would have worked further, but I had not included sufficient front-end gain for copying the signal at great distances. I realized this because instead of my CRT screen printing out random characters, as it would with my transmitter turned off, in a low noise location it stopped displaying anything at all. Not enough gain. So, based on my simple experiments there is no SNR that a good modulation technique is incapable of receiving a signal through if the effective bandwidth is narrow enough, (i.e. a synchronized message repeated enough times to average out the noise.) The only limitation is how long you're willing to wait for the data to appear correctly. BTW, I estimated the EIRP of my transmit antenna to be 7 mW, which is very good for a LowFER antenna and 1 W transmitter. A friend took a receiver with him on his vacations each summer and received the beacon all over the western USA, day and night. So if chirp modulation can reduce the amount of time necessary to receive a given symbol and act in a manner similar to what we were doing with crystal ovens, BPSK, and Coherent, I'd say they have a winner.

  • @dr.routsdigitalcommunicati934
    @dr.routsdigitalcommunicati934 Жыл бұрын

    impressive explaination, perfectly explained

  • @ChaseNoStraighter
    @ChaseNoStraighter4 ай бұрын

    Very well presented! In thinking about the limits to the number of symbols, as the symbol duration increases distortions in propagation will modulate the baseband coordinates and increase the error rate. This is not ‘noise’ and will not show up in simulation. A noise driven delay modulation term would cover this.

  • @JLenival
    @JLenival Жыл бұрын

    Perfect video. It's like a missed Digital Communications lecture that I finally found. Thank you.

  • @ingidiego6407
    @ingidiego64072 жыл бұрын

    Fantastic explanation!

  • @damny0utoobe
    @damny0utoobe2 жыл бұрын

    Great video. I love learning the theory behind stuff like LoRa. Keep it up.

  • @pascalcoole2725
    @pascalcoole27252 жыл бұрын

    Years ago with a friend i did a equivalent experiment using GNU-Radio. Not related to LoRa but the target was using width bandwidth spreadspectrum to get a signal over a long distance 100 - 200 km (60-100Mi) I also added a noise generator to see what happened.... it's long ago, but you retriggered my interest.

  • @fotografm
    @fotografm4 ай бұрын

    Thank you for this excellent explanation !

  • @casev799
    @casev7995 ай бұрын

    For as little as I do know about wireless, and even wired signal communications, this honestly feels like it fills a lot of gaps in my brain

  • @casev799

    @casev799

    5 ай бұрын

    Since KZread has trouble with comments on Shorts, if there are any here that are unrelated, @ me so I can just delete them

  • @walter_mayer
    @walter_mayer4 ай бұрын

    Thank you for this good explanation!

  • @sureshbabuvu
    @sureshbabuvu Жыл бұрын

    Really good explanation

  • @Chastor97
    @Chastor975 ай бұрын

    Explanation is great. Subscribed

  • @ClarkTelecom
    @ClarkTelecom6 ай бұрын

    Super explanation, many thanks!

  • @nathanjaroszynski6210
    @nathanjaroszynski6210Ай бұрын

    at 4:09 you put up both down chirps. Thanks for the lecture

  • @Carolus_64
    @Carolus_646 ай бұрын

    Thanks for the video and very clear explanation. As a graduated in electronic engineering at the Padua university ( the same of Lorenzo Evangelista) I studied spread spectrum in the nineties but at the time I didn't catched the concept: too much theory and few concrete examples. At the time spread spectrum modulation was probably used only by military and hardware was not able to support the computation needed. After this video I want to go deeper on how Lora works, I think I will take the mathlab simulation you have developed to play a bit by myself.

  • @Mehmet-jh5eo
    @Mehmet-jh5eo4 ай бұрын

    Amazing video. Thank you!

  • @SuperLeoSG
    @SuperLeoSG Жыл бұрын

    Awesome explanation, thanks!

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Glad it was helpful!

  • @olfo4100
    @olfo41004 ай бұрын

    Thank you, that's really interesting

  • @mitchbogart8094
    @mitchbogart80945 ай бұрын

    Well, done! I was having a discussion in a math class where I introduced "i" and Complex Numbers to my 9 & 10.5 year old grandsons! (Yes, great joy in doing that!). I was immediately asked words to the effect of, "Well, that's all nice and consistent, and even beautiful if you wish, but it is all based on something that doesn't exist - the square root of negative one. How how can that have any practical value?" My answer then was (based on old analog oscillators I had studied early in EE in college) that when the complex roots of a quadratic equation have an imaginary component, the oscillator is unstable.) Neither a practical nor a very fascinating example for a 10-year old. But this! You've given me the most practical use of complex numbers - even more than the FFT itself - to be the basis of communication with a signal well below the noise level. As a long time amateur radio operator, liking CW (Morse code), we really appreciate digging a usable signal out of the noise. It can save lives. Some ham communications (lower frequency bands) bounce up and down off the ionosphere to make global communication with just milliwatts. Just subscribed. Will properly thank soon!

  • @aliarous7303
    @aliarous7303 Жыл бұрын

    amazing video, thank you sir

  • @TymexComputing
    @TymexComputing Жыл бұрын

    Wow - great explanation - usually there are 3 features but youre only allowed 2 of them - here you can choose 3 simultanously :) Low Bitrate, Low Power and Long Range :) - great idea :)))

  • @TerrisLeonis

    @TerrisLeonis

    4 ай бұрын

    Well technically the desirable traits are High Bitrate, Low Power and Long Range. Power and bitrate are low to begin with. Each time you increment the spreading factor, symbol duration has to double, but so does the number of bits per symbol. I think the trade-off there is in the processing power needed by the larger FFT in the receiver.

  • @luisalejandrosaenz4748
    @luisalejandrosaenz47487 ай бұрын

    Great Video! Thanks so much!

  • @bjorn2625
    @bjorn26256 ай бұрын

    Man, how have I not come across your channel before and how are your subscriber numbers not 10x?! Instant subscribe, super clear explanation thank you!!

  • @mostlymessingabout
    @mostlymessingabout5 ай бұрын

    LoRa is incredible in that it can work below the noise floor

  • @cafe-valente
    @cafe-valente10 ай бұрын

    Absolutely nailed it!!!!!!!

  • @junaid_qadir
    @junaid_qadir2 жыл бұрын

    Amazing lecture indeed. Would you make more tutorials on LoRaWAN implementation, hacking, and defending?

  • @richyoung9662
    @richyoung96624 ай бұрын

    Great explanation. Here is the code if you want to play with it. clear all SF = 7; %Spreading Factor BW = 1000;% Bandwidth Fs = 1000;%Sampling Frequency s = 127; %send symbol '10' SNR = -10;%Signal to Noise Ratio %Generate a data symbol num_samples =(2^SF)*Fs/BW; k = s; %add s to k to start (defines the data symbol) lora_symbol = zeros(1,num_samples); for n=1:num_samples if k>= (2^SF) k = k-2^SF; end k = k+1; lora_symbol(n) = (1/(sqrt(2^SF)))*exp(1i*2*pi*(k)*(k/(2^SF*2))); end loop = 100; ind2 = zeros(1,loop); for j=1:loop %Add noise lora_symbol_noisy = awgn(lora_symbol,SNR,'measured'); %Transmit %Receiver below % Generate the Base Down Chirp base_down_chirp = zeros(1,num_samples); k=0; for n=1:num_samples if k>= (2^SF) k = k-2^SF; end k = k + 1; base_down_chirp(n) = (1/(sqrt(2^SF)))*(exp(-1i*2*pi*(k)*(k/(2^SF*2)))); end dechirped = lora_symbol_noisy.*(base_down_chirp); corrs = (abs(fft(dechirped)).^2); figure(1); plot(corrs) [~, ind] = max(corrs); ind2(j) = ind; pause(0.01) end figure(2); histogram(ind2,2^SF) symbol_error_rate = sum(ind2~=s+1)/j figure(3); spectrogram(lora_symbol)

  • @soybeanrice
    @soybeanrice2 жыл бұрын

    Overall great video. Good job extracting the bottom line information from the sinusoidal equations. Small correction needed: 20 db implies a magnitude of 100, not 10. Meaning the at -20db, the Noise is 100x the Signal magnitude, further driving the point of just how effective the signaling scheme is at handling noise, especially when you show the -10dB signal... just imagine 10x that. I do wish that you explained the Y axis of the Err Rate vs SNR a little bit, because the way its graphed in the video (right to left) almost implies that the higher value on the Y axis is good, but for anyone viewing, having an error rate of 1 is of course unusable. Maybe a horizontal line on the graph that shows an acceptable error rate wouldve helped. Oh, and thank you VERY much for providing a Matlab example

  • @andrewbourne2296
    @andrewbourne22965 ай бұрын

    What an extremely well presented video on a very complex subject. What I was wondering is what kind of bit rate you expect from this modulation scheme. You could always add a Foreward Error Correction protocol (FEC) to the original signal to improve the SNR. We use that extensively on high speed optical transmission systems

  • @erikziak1249
    @erikziak12495 ай бұрын

    While watching this, my brain started to think about it deeply. Ultimately I fell asleep. I guess my brain was overwhelmed and turned off. 😀

  • @nikooplayer
    @nikooplayer4 ай бұрын

    Although I wasn't able to follow most of the parts related to the mathematical bases, but I got the concept behind and I've learned something new and interesting. I am sure I will never use it... but thanks :)

  • @thecriss88
    @thecriss88 Жыл бұрын

    you deserve more subs and viewers

  • @the.25.dreamer
    @the.25.dreamer2 жыл бұрын

    Really interesting video! :)

  • @thanhcongnguyen55
    @thanhcongnguyen552 жыл бұрын

    Good explanation. Keep it up

  • @daviddavidson2357
    @daviddavidson23577 ай бұрын

    "Spreading factor is between 7 and 12 in Lora" Fascinating, I'll be sure to let her know.

  • @mitchhilger5394
    @mitchhilger53944 ай бұрын

    Fantastic analysis and explanation of the signal. So does this breakdown such that many of the newer SDR equipment could utilize this as a new digital mode as well? This could be a new mode to explore for ham radio.

  • @mcwolfbeast
    @mcwolfbeast5 ай бұрын

    Thanks for the clear explanation! I do wonder what happens if there are 2 LoRa transmitters in an area though, how would the receiver distinguish between them?

  • @repatch43
    @repatch434 ай бұрын

    Everything about Lora is counterintuitive. Increasing the spreading factor which means increasing the possible symbols IMPROVES performance? Incredible how the maths proves the fact. Does make you think about what more advanced tech the military has hidden away

  • @cbowns

    @cbowns

    4 ай бұрын

    As noted in other comments, the data rate falls in relation to improvement in noise performance

  • @_a_x_s_
    @_a_x_s_ Жыл бұрын

    Wow beautiful! From a new modulation concept with a complex maths expressions to a smart way of computational representation, that’s incredible! Cannot imagine how people invented this smart are!

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Thanks! Yes, it is a smart idea with a lot of applications.

  • @TheAlchaemist
    @TheAlchaemist6 ай бұрын

    Let me see, as stated in some comments, if the SF increases by 1, the symbol length (and window) doubles. That effectively lowers the bitrate, which makes total sense. Then, why the chirp at all? You could do exactly the same with nFSK, just have more possible values per symbol, over a longer time with a lower bitrate. For this to work so well, the chirp has to provide some important benefit. Perhaps less reliance in the oscillator stability? I'd love to see a comparison between LoRa and an equivalent nFSK in Matlab. BTW awesome video!

  • @realsolarcars

    @realsolarcars

    4 ай бұрын

    I guess the nFSK system would fail much sooner due to frequency selective multipath or constant carrier interference. That interference won't match the chirp rate. The difference wouldn't show in a simulation using AGWN like in this video. Just a guess, this video is the only real research I've done into LoRa.

  • @TheAlchaemist

    @TheAlchaemist

    4 ай бұрын

    @realsolarcars I guess, but you could address those problems in nFSK in an upper level of spreading and FEC, no one said the FSK should be simple and straight, after all LoRa isn't. I think what I try to say is that there is no real need for the continuous shifting in frequency, you could instead do discrete jumping between the n subcarriers. The reason could very well be making it patentable. Anyway I am just guessing. Regards!

  • @senfilatechnologies2938

    @senfilatechnologies2938

    4 ай бұрын

    The benefit is each symbol is spread across the entire bandwidth, so no symbol can be lost in a multipath null, unlike what could happen with nFSK. When you DONT use forward error correction this has big advantage!

  • @bobowzki
    @bobowzki4 ай бұрын

    The clearest explanation in the history of explanations.

  • @rohandvivedi
    @rohandvivedi24 күн бұрын

    you just earned a subscriber.

  • @martinsimbona6145
    @martinsimbona61452 жыл бұрын

    Incredible!

  • @nunyabidness9257
    @nunyabidness9257 Жыл бұрын

    Thanks for the video-i’m an Amateur radio operator with an interest in digital modes and LORA. I’m not sophisticated enough to follow along with the calculations in the video, but I understood the scene behind interpreting the symbols based on your description.

  • @VisualElectric_

    @VisualElectric_

    Жыл бұрын

    Glad it was helpful!

  • @rikvermeer1325
    @rikvermeer13252 жыл бұрын

    Thanks

  • @siberx4
    @siberx44 ай бұрын

    Somehow, I just knew the clever math trick would involve fourier transforms. Invariably in signals, compression, or other similar domains, converting between time and frequency domains opens up all sorts of interesting options for improving the efficiency of the process. Great video, very enlightening! LoRa is no longer magic to me. I'd love to see you cover CDMA, especially the way code-based modulations are combined with other methods to provide efficient band sharing and tolerance for multipath interference.

  • @richardamullens
    @richardamullens4 ай бұрын

    Thank you

  • @JxH
    @JxH5 ай бұрын

    Awesome. Thank you. +Subscribed. 🙂

  • @neilclay5835
    @neilclay58355 ай бұрын

    fascinating,thanks

  • @darkmandrake69
    @darkmandrake695 ай бұрын

    Very good 🙌👏👏👏

  • @void94
    @void94 Жыл бұрын

    Wow, what a helpful video. Actually I'm doing some studies on LPWAN Technologies and tried to figure out where the limits of LoRa are. The other technology that I've tested is way weaker and loses connection at a SNR of like -2.

  • @RyanLynch1
    @RyanLynch1 Жыл бұрын

    wow. I'm totally not a EE or hardware guy but I find this so interesting. I'm surprising that a higher SF results in lower error rare since it seems to me that a higher SF actually means more data is transmitted (unless I'm misunderstanding or somehow the length of transmission is longer for compensate) but with lower error. very cool video!!!

  • @zerpharet

    @zerpharet

    Жыл бұрын

    You are correct, there is one thing: With a higher SF the chirps also get longer. So the bitrate goes down although there are more symbols.

  • @andrewrossy
    @andrewrossy4 ай бұрын

    Wow, what a great video explanation. Thankyou. So if I get this correctly there is a signal hidden in the noise, you just need to know how to decode ... so wonder what the implications of something like this is for SETI and so on. Would the checks that SETI perform still just show noise as well.

  • @rfly-fpv
    @rfly-fpv2 жыл бұрын

    Amazing video! If i'm not wrong LoRa technique was used in Express LRS open source system used for example in FPV drones. You can get amazing range even at super small TinyWhoop like Mobula 7 1S ELRS. There is super tiny ceramic antenna and this system rocks in terms of penetration even on small transmitter power.

  • @r0cketplumber
    @r0cketplumber5 ай бұрын

    Armsman Pham Trinli at the On-Off star would be very happy with this encoding scheme for his nanopower localizers...

  • @DJSpreadbury
    @DJSpreadbury4 ай бұрын

    That was a very nice description - thank you. As a retired signal processing engineer it's nice to hear a good explanation! You suggest that the performance might keep on increasing with spreading factor without limit - it would be interesting (necessary, even) to include the initial detecton and synchronisation process, in noise, in your simulation, and then perhaps the effects of multipath, fading and Doppler. The decoder could be quite sensitive to symbol timing variation thoughout the packet - how long would a packet be? Terrestrial DAB modulation is based on frequencies rather than chirps, but the receive process is not disimilar - do you have any idea of the relative performance? I'm not familiar with the papers or the intended applications, but I would expect there to be further gains from hard or soft error detection/correction coding at the data level.

  • @RandomNullpointer

    @RandomNullpointer

    4 ай бұрын

    Very good points raised here 👍

  • @gordonhardman7396
    @gordonhardman7396 Жыл бұрын

    Excellent video. Is it possible to get the Matlab code?

  • @turtility
    @turtility Жыл бұрын

    YOU ARE GREAT !!!

  • @tonyb8660
    @tonyb86606 ай бұрын

    thanks for whatever this is... sounded informashunny and signal to noise wallacazam 4 Hz got it Thanks!

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