#253
Переглядів 38,602
День томуPC based video, by request, while I recouperate from my ankle injury.
This video shows how to capture and analyze WiFi (WLAN) signals off the air, and perform some analysis on those signals. OTA (over the air) signal capture and analysis of 2.4GHz ISM band signals presents many challenges including interference, trigger challenges and multi-path interference. However, given these challenges, with care you can achieve reasonable results. I used a Tektronix RSA306B for this video, but the same techniques apply to all USB based RSAs. The benchtop RSA products include additional trigger functionality which greatly improves the ease of triggering specifically on the signals of interest. I show analysis of 802.11g signals, but options allow analysis for other variations of the standard including 802.11b, 802.11a, 802.11n, 802.11j, 802.11ac, 802.11p.
@jeromekerngarcia 6 років тому
Another good one! I took a self-imposed YT hiatus for a few months, only to come back & see you're still producing great content! Thanks...
@johanfourie9385 7 років тому
Hi Alan. Thank you very much for this video. I can't wait to get in front of my RSA to perform these measurements. This is very helpful. SignalVu with the Tektronix USB Analyzers is a very powerful full combination.
@caulktel 7 років тому
Great video Alan, I envy you getting to use all this cool equipment and actually know how to use it.
@w2aew 7 років тому
Thanks - I am very lucky to have this job!
@koffibanan3099 7 років тому
You've got some fantastic videos! Thanks! However, I always feel dumb after watching one; so much stuff left to learn. If you ever feel like doing a tutorial on the different modulation schemes, I'd be very grateful. All the best!
@7head7metal7 7 років тому
There is an older Tek RSA living in our lab at University, and it serves us quite well! I always love to work with it :)
@w2aew 7 років тому
Cool! If you ever have any questions about it, be sure to let me know.
@dLimboStick 7 років тому
Love it! I used to do this with an HP 89441 VSA, but this is beautiful. I'm doing IP stuff now, but I sure do miss the world of RF. Thanks for another great video!
@w2aew 7 років тому
The RSAs are really cool instruments.
@senohpi 7 років тому
Thanks Alan, good educational video, now i have to buy a SA with constellation diagram option :)
@geordirendum583 7 років тому
i got a good grade thanks to you in my radiocommunication exam !
@w2aew 7 років тому
Congratulations and thank you!
@geordirendum583 7 років тому
w2aew you deserve more subs ! Keep up the good work !
@kunalbharucha2054 5 років тому
Thanks!! It is a very good video showing theoretical concepts practically. Do you have any video or can upload some video on LTE OTA signal spectrum? Also, I would like to see the spectrum when it is SISO and MIMO implementation on spectrum analyzer?
@magickandre 5 років тому
Thanks for sharing. Is there a possibility of a tutorial explaining digital filters (IIR and FIR) in easy layman's terms. There are far too many of theses tutorials online that are to in depth and mathematical. Once again thanks for all your excellent videos. Regards
@norm1124 7 років тому
very nice, thank you
@kassima9892 7 років тому
First of all I would like to appreciate for your well explained all videos. I always watching a lot of yours videos again and again. I have a request, can you please prepare a video about none linear mixer which create sum and difference when we mix two signals. I want to know how it is creating two other frequencies. Please explain through graphical demonstration without mathematics. It will be highly appreciated. thanks in advance
@w2aew 7 років тому
I already have a few videos on mixers. Here are a few for your to view: Basics of Mixers and Frequency Conversion: ukposts.info/have/v-deo/hZ1oi5yNsahiwqM.html How a diode ring mixer works: ukposts.info/have/v-deo/oqWfqXuupIeHsmw.html How a Gilbert Cell mixer works: ukposts.info/have/v-deo/b56eoZhnp6eFtmQ.html
@kassima9892 7 років тому
Thank you so much Praying for your health
@ATUS1213 4 роки тому
Hi Alan, hope you are doing good. have you thought about making video of layer mapping for MIMO (ref. LTE phy layer processing) I mean after watching #262 my hunger for next level is ever increasing 😀. Thanks again for you time and effort on UKposts.
@pauldeboer 7 років тому
If you go on producing these videos sooner or later I have to buy an RSA... The software looks so powerful!
@w2aew 7 років тому
The RSAs are incredibly powerful and flexible instruments - and the user interface (shown here) is the same on all of them - from the least expensive USB based instruments, to the high performance wideband benchtop instruments.
@CassianoRabelo 7 років тому
Hi Alan. Great video, as always! Could you please suggest a least expensive USB RSA for beginners to play around? Thanks!
@w2aew 7 років тому
Instruments like the RSAs are really geared towards professional users. The least expensive RSA that uses this software is the RSA306B. The earlier version of this unit (the RSA306) can often be found at bargain prices.
@manvendrasingh5853 4 роки тому
Thank you very much!
@josephpacheco7096 7 років тому
Great videos! I recently took a Hands-on wireless communication class and we would analyze signals using SDR USRP2. Would you be willing to make a video about understanding BER curves and how to interpret them?
@kf9ug8365 5 років тому
Thank you for your video as I haven't had experience with the RSA306B & SignalVu before a week ago. 73s de KF9UG
@w2aew 5 років тому
I have several other videos on the RSA306B and SignalVu-PC, so be sure to let me know if you have any questions.
@kf9ug8365 5 років тому
I watched the other 2 videos (I could find) that you did for the RSA306B. They did help teach me other features of SignalVu-PC I didn't know about. Through your videos I have been able to successfully capture/analyze 802.11b signals I needed to be able to do for a new product. Now my task is to take what I learned and issue the appropriate SCPI commands to do the same things. Thank you for taking the time to make these videos.
@GeorgeTsiros 7 років тому
that qam64 looks quite gnarly >_
@leppie 7 років тому
Mind blown
@pulesjet 5 років тому
The Tektronix RSA306B is way above my pay grade and ways and means. Trying to figure out how I can just see WiFi signals using a Regular SDR Dongle. It would seem some do in fact obtain signals that far out of and above the band width advertised.
@robertw1871 5 років тому
I don’t even want to know what Tek charges for those software modules, pretty powerful stuff though.
@steveedwards90 7 років тому
sir thanks for all your work your knowledge is brilliant hope the ankle is healing ok something for you to ponder think about my skill is pure amateur at best compared to you FM deviation meter in the UK are almost non-existent so without complicated chips is it possible to see a 145mhz FM deviation signal on a 50mhz scope it's what I have ?? I need to adjust an old trio 7500 deviation the audio is a little quiet it was a freebie just needed a service ( NO service data available )I want to see the devation signal on the scope is it possible thanks
@w2aew 7 років тому
It's not possible to see the FM deviation of a 145MHz signal on an oscilloscope, especially a 50 MHz scope. probably best to adjust the tx and listening to or measuring the result on a receiver, comparing response to known good tx.
@43SunSon 7 років тому
Question. Sir, do you have any video about pulse shaping filter ? If not, could you consider about making one like you did in your video about IQ signal? Your IQ signal tutorial video is the best tutorial video I ever seen, I am not joking. Easy to understand, because you combined with math example, and real equipment example. Pulse shaping filter is one of the very important concepts in wireless communication, I think. Thank you!!
@w2aew 7 років тому
I can add that request to my long list of future topics.
@43SunSon 7 років тому
Thank you in advance. It will be really awesome you could make one :)
@peterb8387 7 років тому
Hello Alan, I have an issue. I have constructed a direct FM modulator with something like 56 MHz carrier using a 100 pf varicap. The thing is all the books say as the modulating frequency drops for the same frequency deviation the spectrum should get more populated and closer to continuous. The opposite seems to be happening on my analyzer display where increasing the modulating frequency from my signal generator results this effect and decreasing the frequency makes the spectrum more sparse and seems to decrease the deviation down to what looks like very NBFM and no signal at all when the modulating frequency is like at 100 Hz or less. Any ideas ? Do varactor diodes have sensitivities to the base band modulation frequency ? Thanks, Peter
@w2aew 7 років тому
The number of sidebands and their magnitudes depends on the modulation index - which is the Peak Deviation divided by the baseband modulating frequency. The sideband amplitudes then follow a set of Bessel function curves. You can see a little background regarding this in this video: ukposts.info/have/v-deo/cHlzg4-mgIxmzmw.html Varactors shouldn't really have any sensistivity to the baseband frequency - just make sure that your drive circuitry doesn't. Here is one more video showing an alternative way to measure FM deviation with a spectrum analyzer: ukposts.info/have/v-deo/hqdkk61of6idpqc.html
@jsayres4253 3 роки тому
I was told that the sincgars radios used by military have a shorter tx range when using secure communications option. From what I can tell this just implements FHSS, which seems like it has same PSD as using narrow band of same carrier frequency so it should have same transmit range right?
@w2aew 3 роки тому
The reduced range is likely due to the fact that the receiver must have wider BW to capture each hop...
@edward17829991 3 роки тому
Can we use any tools to decode the message in each captured signal? My goal is to decode Wi-Fi beacons in the air. Can I monitor all Wi-Fi channels at once?
@JGunlimited 5 років тому
Does the symbol table show the sent data decoded as hex? I.e. are those the data packets in hexadecimal? I'm trying to understand the link between the analog data captured and the digital one interpreted by devices.
@w2aew 5 років тому
The symbol table shows the raw transmitted symbols in hex. I believe that there is some encoding or scrambling employed between the actual data and the transmitted symbols.
@JGunlimited 5 років тому
Ah, thanks! So if I were to grab the data in the table (which I assume is encrypted via WEP/WPA) and run it through some decryption algorithm, I would get the actual data...
@BitanMallik 7 років тому
Dear Alan, I am a grad student, studying electronics and communication. I like your videos a lot. My interest area includes broadband communication. Currently I am researching about CDR circuits and their implementation in burst mode. Could you please throw some light over this?! Thanks Anyway!
@w2aew 7 років тому
This is a subject that wouldn't be effectively covered in just a 10 minute video. Usually will involve some type of PLL with a fast response, but will also depend pretty highly on the nature of the data being sent in the bursts or packets. I am currently unable to get into my lab due to my broken ankle, so it's going to be a few months before I can do any new bench videos.
@BitanMallik 7 років тому
In case you have any reference in your mind. Please do share. I wish you get well soon :)
@w2aew 7 років тому
There appears to be a fair amount of information available due to the use of burst mode CDR in GPON applications. Many FPGA mfrs like Xilinx have published some info. Might be worth exploring existing drives like this one front Analog: www.analog.com/media/en/technical-documentation/data-sheets/ADN2855.pdf ...and here is an academic paper on the subject: pdfs.semanticscholar.org/4efb/189ce58816e21541778c7b6282dcf8c5c4e8.pdf
@ivayloiliev6641 7 років тому
The free version of SignalVu does not include this functionality, correct? Which option do you need to purchase for this? Thx...
@w2aew 7 років тому
Correct, wlan analysis is an option. SV23 covers 802.11a/b/g/j/p. SV24 covers n, and SV25 covers AC. Any/all options can be turned for free 30 day trial.
@43SunSon 7 років тому
Question, how to find out which channel I am in? I put my analyzer to 2.4Ghz now, but how do I know which wifi channel, my cell phone is using? thank you!
@w2aew 7 років тому
Do something on the your phone that uses a lot of data, then move the phone close to the antenna and look for the highest peak signal in the 2.4GHz ISM band.
@43SunSon 7 років тому
Yeah, I already see that. Thank you again.
@vonzigle 7 років тому
Sorry, but I can't understand one word in your descriptions--is it 16 quan or 16 quam, and what does that stand for? Thanks!
@w2aew 7 років тому
It is QAM, pronounced like "quam". It stands for Quadrature Amplitude Modulation. 16QAM means that there are 16 distinct states of amplitude and phase that represent the digital symbols being sent.
@vonzigle 7 років тому
w2aew Learn something every day--thanks again!
@43SunSon 7 років тому
May I ask which equipment you are using? It seems that you are doing this on a PC. Thanks.
@w2aew 7 років тому
I am using a Tektronix RSA306B Real-Time Spectrum Analyzer, being controlled by a software app called SignalVu-PC running on my laptop. Tek makes three families of real-time spectrum analyzers that are controlled over USB3.0 - the RSA300 series, the RSA500 series and the RSA600 series. Each of these is controlled by SignalVu-PC. The base version of this software is available for free from tek.com. There are optional analysis features (such as this WLAN analysis) which are purchased options.
@nraynaud 7 років тому
may I ask the public price for the entire package of software, hardware and options necessary to create this demonstration?
@43SunSon 7 років тому
Thank you!
@w2aew 7 років тому
List price for RSA306B is $3890. Most analysis options are
@43SunSon 7 років тому
Dear sir, may I ask a question again. I watched some of your videos, you are very good, you do truly understand those things. May I ask you, how do you study? Where did you learn? From school? or just do it by yourself? In case you study by yourself, possible to share some experiences to me? To be honest, I am in the major of wireless communications, but I found that your knowledge is way much better than me.
@jeffvillasis1189 7 років тому
Can you so that on your phone?
@w2aew 7 років тому
Unfortunately no. The realtime processing of 40MHz wide RF data requires the full bandwidth of the USB3 port and an i5 or i7 processor running 64 bit win7 or higher.
@lga7758 3 роки тому
can u give a download link to software used.
@w2aew 3 роки тому
www.tek.com/spectrum-analyzer/rsa306-software/signalvupc-vector-signal-analysis-software--v410022
@lga7758 3 роки тому
@@w2aew how do i DL it
@w2aew 3 роки тому
@@lga7758 Just create a free account on tek.com, login, and download it from the link on that page.
@lga7758 3 роки тому
@@w2aew it says virus why does it detect
@ericcsuf 6 років тому
Interesting in the way that Homes of the Rich and Famous is interesting. Maybe your videos should be rated like restaurant reviews, with a string of $. One $ is of interest to anyone with an interest in electronics. $$$$$ is of interest to anyone with a basement full of the latest Tektronix gear.
@w2aew 6 років тому
My day job is as a Field Applications Engineer for Tektronix. Some of the videos that I post on my channel are by request of my commercial / industrial / professional engineering customers (like this one).
@lga7758 3 роки тому
i don't see the colored lines in the center of screen
@w2aew 3 роки тому
This software works with Tektronix USB based spectrum analyzers.
@lga7758 3 роки тому
@@w2aew what is that
@w2aew 3 роки тому
@@lga7758 www.tek.com/spectrum-analyzer/rsa306
@lga7758 3 роки тому
@@w2aew any cheaper way
@jaa93997 7 років тому
🤔 maybe we can see 5GHz WiFi in action ?
@w2aew 7 років тому
Unfortunately, I don't have any 5GHz WiFi devices here to show. Capture and analysis process would be the same, other than selecting the right standard (802.11n for example), and the active channel...
@RLG261 7 років тому
What is the purpose of this? What does one do with the information gained? What is a real life application?
@w2aew 7 років тому
Could be one of several things: examining channel utilization, determining which MCS (modulation coding scheme) is being used by a device, examining antenna performance, checking EVM (signal quality) vs time or frequency (subcarrier), etc.
@aamir122a 5 років тому
you can do something like this ukposts.info/have/v-deo/o3J3gamQbJCBkaM.html
@frankie_soprano 5 років тому
You Have to pay for the the constellations analysis :(
@w2aew 5 років тому
Yes, it is one of the options available. You can enable a free 30 day trial license through the website.
@samsami1130 3 роки тому
thanks a lot for your efforts dear, i wonder if we can use the new nanonva to do the same !!
@w2aew 3 роки тому
Sorry, no, for numerous reasons (it's not a spectrum analyzer, it can't record RF signals over time, etc.)
@samsami1130 3 роки тому
@@w2aew appreciate your reply 🙏 ❤... many thanks to all your works and efforts on this channel ...
w2aew
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