#286

[@zvpunry1971]

Just some information that may be helpful for beginners: 0.) Programs like GNU Radio allow the use of sound-cards to learn the basics of software defined radio. Build simple digital transmitters and receivers that use the microphone and speakers instead of a SDR. 1.) There is not much difference between the blue/plastic and the silver/metal rtl-sdr. The bandwidth and the software is the same, both are useful up to 2.2 MSps but can be pushed up to 3 MSps (no difference here). The difference is, that the metal one has a _much_ better connector, SMA instead of MCX. The blue plastic one also has a really cheap crystal oscillator, it wanders around whenever the temperature changes. The silver/metal version has a temperature compensated oscillator, it measures the temperature and uses this to correct its drift, so it is much more stable. The drift normally is a few parts per million (it it is 10ppm, this would be 10 Hz at 1 MHz, but already 1000 Hz if you receive something on 100 MHz or 10 kHz if you are interested in 1000 MHz signals).The TCXO has only 0.5 ppm drift and the cheap crystal up to 20ppm. 2.) The most important things are antennas and short good coaxial cables. They decide about the signal quality. The cheapest RTL-SDR with a good antenna (and band-filters, see #3) is better than a 10000€ SDR with a crappy antenna. Beginners should go for the cheapest SDR and use the saved money for the antenna. With RTL-SDRs it is cheaper to use a long USB cable and get the SDR close to the antenna and away from the PC (which may create interfering emissions) than a good coax. An old satellite dish with LNB, a bias-t (basically a box with two coaxial connectors, a coil and a capacitor) and a power supply that can deliver 14V (a bunch of batteries) are enough to receive that satellite shown in the video. More information and WebSDR: eshail.batc.org.uk/nb/ amsat-dl.org/p4-a-nb-transponder-bandplan-and-operating-guidelines/ 3.) Almost all SDR have wide open inputs. All signals received together (in case of the HackRF everything between 1 and 6000 MHz) must not exceed the maximum allowable signal strength. It's a common source of problems for beginners. They get interested in weak signals from far away and enable the AGC (automatic gain control) to get a nice strong signal but the signal strength (including the noise floor) jumps up and down because the AGC constantly increases and decreases the gain. Then they switch the AGC off and manually set the gain to some value, but then some mystery signals appear, signals that aren't there. That is what happens if the sum of the received signals exceed the maximum allowable signal strength, which turns amplifiers and ADCs into mixers that mix different received signals and produce these mystery signals. Fortunately there is a solution to this: Filters. If the offending signals are local FM broadcast stations, there are band-stop filters for 88-108 MHz that eliminate this problem (but Airplanes, DAB, DVB-T and cellphones may still interfere and would require separate band stop filters). If your frequency of interest is clearly defined, use a band-filter that discards everything except the interesting band. And even better is a pre-selector, that is a device full of band-filters and some switches to select them depending on your needs. And the luxury variant is something like this: www.crowdsupply.com/lime-micro/limerfe It is a pre-selector that is controllable by software. ;-) Do it yourself band-stop filters however can be extremely cheap. The cheapest is the quarter wave stub. If you have only one interfering FM station at 100 MHz, which is a wavelength of 3 meters, add a 75cm (1/4 of 3 meters) piece of coax to the antenna cable. The waves will travel to the open end, get reflected and come back 180° out of phase. They will destructively interfere with the offending signal and thereby stopping it from reaching the SDR. The waves travel only 2/3 the speed of light in coax, so the 75cm will be way too long (the final length will be around 50cm). To tune such a stub, you can connect a noise source instead of the antenna and look at the dip in the noise. If the frequency of the dip will be too low, cut a bit of coax off and see how that dip rises in frequency. If it gets too high you have cut off too much (just push some copper wire into the open end of the coax). 4.) Almost all SDR have wide open outputs! The produced signal may contain spurious emissions and harmonics. If a signal is produced, say at 145 MHz, you need at least a low-pass filter above your frequency but below twice that frequency (i.e. 200 MHz) to get rid of all harmonics. Then look at the signal with a spectrum analyzer (i.e. another SDR)! If you have tuned your SDR to 145 MHz (center frequency), modulated some NFM (narrow frequency modulation) signal at +500 kHz and send it to the SDR and expect it to only transmit at 145.5 MHz, you might also see a copy of it at 144.5 MHz. This happens due to I/Q imbalance and this error can be corrected. Then you might produce a good signal and send through an amplifier, which again might add harmonics that must be filtered with another low-pass filter.

[@AndreasSpiess]

Thank you for adding more content. As I said: This channel has more content in the comments than in the videos ;-)

[@BruceNitroxpro]

Or, you can get a pre-engineered solution by spending more MONEY! Like the series of new SDR transceivers (they both receive and transmit) from Icom which have been made for radio amateur operators. For ONLY around a thousand dollars (time is money!) you can buy a wide band receiver and band specific transmitter from well below the AM radio band (like 30.0 KHz to 74 MHz) to the amateur radio transmitted band, 6 M (50 MHz range). Look for an Icom 7300, like mine! GRIN! I am a lucky fellow to own one which works BETTER than I EVER thought it would! This is KQ2E

[@zvpunry1971]

I'd rather build a HPSDR/OpenHPSDR based station, which will end up even more expensive than an icom 7300, than giving that money to icom/yaesu/kenwood. And if I weren't able to or didn't want to build something like that, I'd buy a radio from Apache Labs. Those old companies (from which I prefer kenwood) have a certain lack of technological progress. They only moved to more modern technology when projects like HPSDR and the commercial offerings from Apache Labs and Flex Radio became a threat. And they still use tactics like vendor lock-in (Just look at the pin-outs of microphone connectors) and they intentionally make design decisions that result in people buying options (TCXO, roofing filters and so on). And when DMR became popular, yaesu suddenly came up with their "yaesu system fusion". At least d*star hasn't the name icom in its name. ;)

[@kwastek]

This comment should be pinned.

[@SuperSetright]

@@zvpunry1971 It's called competition....and it drives innovation.

[@MattBrunton1965]

I'm only 6 minutes in, and I've never seen the concept of mixer and IF explained so clearly. Thanks Andreas!

[@AndreasSpiess]

You are welcome! And I hope, the rest was also ok ;-)

[@basimhassoun2147]

Yeah! Andreas as an absolute MADLAD!

[@jeroenjeroen]

Hats off for this great video on such a complex topic. I have been staring at my sdr dab dongle for months, but after watching this episode I'm ready to experiment. Thanks!

[@AndreasSpiess]

Enjoy experimenting. It will not always be easy, but rewarding...

[@briancrane7634]

A delightful summary! I was a radar systems engineer for 30 years...we were using I/Q demod in the '80's...I am retired 10 years now...this video was like going home for a nice meal and a chat! Many thanks!

[@AndreasSpiess]

Interesting that you already used I/Q signals in the 80s. Very early. But maybe your industry also had deeep pockets back then ;-)

[@murrij]

One of the best (possibly THE best) SDR intro videos there is.

[@AndreasSpiess]

Thank you!

[@MoTown44240]

Andreas, I chuckled when you mentioned 'we' began listening to FM radio at a young age. FM came into my life as a teenager around 1962. AM broadcast stations were king of the airwaves and it took almost a decade for FM to overtake the throne. I enjoyed this video. Thanks for taking time to present it.

[@AndreasSpiess]

You are welcome. Here in Switzerland, FM was probably a little faster as our country is very small.

[@avejst]

Impressive overview as always You are doing a great job, of opening new doors for the community Thanks for sharing👍😀

[@AndreasSpiess]

You are welcome. I hope it will help my viewers to understand this complex technology a little better.

[@aronhighgrove4100]

@@AndreasSpiess Thanks, it's really an excellent video, including the very useful links!

[@jamiegoegebeur2239]

Yesh It does! I'm an IoT teacher and was looking add these Ikea plugs I bought year ago after your video. Wanted to cut it open aswell. But as I couldn't do anything with it at thé moment I let it rest. This sparked a lot of interest in thé zigbee platform ;o

[@T3chFlicks]

You are the teacher I never had. Keep doing what you do! :)

[@AndreasSpiess]

I will!

[@xx-gk3et]

👏

[@Vikas_Singh_Kushwaha]

Don't know whenever I search some tricky rf concept, I always find one of your videos on it ! Thanks for the great content and efforts.

[@AndreasSpiess]

You are welcome!

[@hardickbora]

The best video on the subject i have seen so far. Its a one-stop shop for anyone looking to understand, 1. What is a radio? 2. What it does? (In simple terms) 3. How does SDR improve upon the prevalent solutions? And the narration and the narrator is fantastic. Thank you for the video.

[@AndreasSpiess]

Thank you for your kind words!

[@mr.e5988]

Thanks Andreas. This was a comprehensive 1% information for those of us getting into SDR. Thank you for your time and effort!

[@AndreasSpiess]

Glad it was helpful!

[@darthvader8433]

I did my radio trade apprenticeship 40 years ago. I had heard of SDR but never lifted its skirt. You have blown my mind with the ingenuity of the people who developed it, and with the possibilities.

[@AndreasSpiess]

It is an interesting technology, indeed. And it will replace a lot of the things we learned in our youth...

[@MerlinFox]

A great explanation, thank you! SDR revived my interest in a radio, and I’m now an M0 in the UK 👍

[@AndreasSpiess]

Congratulations!

[@OldDogNewTrick]

My mind is blown. Here it is November 2019, and I am a 79 year old tech junkie but I never knew about SDR until now. I built crystal radios when I was a boy in the 1950s, worked for a while as a radio-TV technician in the early 60s, and with mainframe computers from mid 60s until I retired. I am amazed at how far technology has advanced in my lifetime. Thanks for the great info.

[@demerit5]

If it makes you feel better I believe Software Defined Radio has really only started to pick up steam in the last 10 years or so.

[@AndreasSpiess]

@olddognewtricks: It is good you still are interested in these new things ;-)

[@Fagrache]

Great job Mr Andreas, you have explained that as simple as possible. Respect from Morocco.

[@AndreasSpiess]

Thank you!

[@borisj4054]

Wonderful to find someone who really knows what they are talking about.

[@AndreasSpiess]

Thank you!

[@alexanderl.2689]

Great video! Small but important correction at 7:55. In order to digitize a 10.7 MHz signal, the ADC (Analog Digital Converter) sampling frequency must be at least 2*10.7 MHz (21.4 MHz) due to the Nyquist criterion. Even if you'r interested in only the 150 kHz FM signal the Nyquist criterion must be satisfied up to the highest possible frequency within your signal, otherwise you will get aliasing effects.

[@AndreasSpiess]

You are right.

[@dirkbell6373]

@@AndreasSpiess However, it is possible that with a lower sample rate the aliased signal can be demodulated, particularly if you filter out other signals that may alias to the same frequency, or you are lucky enough that none do. A lot of radios are built that have high frequency band limiting followed by undersampling (sampling lower, perhaps much lower, than the Nyquist sampling rate for the original signal frequency location). The undersampling does not preserve the original signal, but can shift the signal to a lower digital frequency that may be able to be demodulated. This is not in conflict with the Nyquist Theorem. Some care may be required to ensure that the aliased signal does not corrupt itself. For bandpass signals the minimum sampling rate is more than twice the bandpass signal bandwidth, exactly how much more will depend on the sample rate and the signal frequency range.

[@smartypants5036]

Thank you for this information. As a complete novice I would be be so happy just to put FM radio on my laptop and expand from there. This presentation has been by far the most helpful in getting my head around this new innovation.

[@AndreasSpiess]

It is no more new. But still very useful...

[@waltsteinchen]

Thanks Andreas again for such a great video! .. It must be incredible time consuming to deal with such a complex area and summarize it in such a great way for us!

[@AndreasSpiess]

This one took me a year of hesitation. I had a lot of respect and needed some time to get my brains around it ;-)

[@rohithvishaal]

I have to present a technical seminar on SDRs tomorrow, this video is definitely a gem. Thanks for this professor.

[@AndreasSpiess]

I hope it went well!

[@rohithvishaal]

@@AndreasSpiess my presentation really went well professor and I passed. Thanks for the video again😁

[@wm6h]

Digital Radios with these capabilities have been around since the 1980’s. A Software Defined Radio is a Digital Radio that has been processed by a Marketing Department. We can start calling them Digital Radios again with no loss of generality-as we say in math class. Thank you for the summary charts.

[@AndreasSpiess]

I think the addition of cheap computing power including open-source software changed quite a lot. So, "Software" in my opinion is also an important factor, not only digitizing...

[@lawrencedoliveiro9104]

Back then, “digital” was heavily overused as a marketing term. What’s different about modern products is their software programmability.

[@jozefgoral6812]

Very interesting material. I appreciate your work and good luck in further developing your passions. Being your student is pure pleasure.

[@AndreasSpiess]

Thank you. I am glad that you like my videos.

[@ats89117]

Great video, with one minor oversight. The negative frequencies aren't 'cut off' as stated in the video. They are aliased, i.e. folded over the DC axis. One of these days I will get around to using an SDR to detect nearby receivers by detecting their LO leakage...

[@FrankZosso]

"One of these days I will get around to using an SDR to detect nearby receivers by detecting their LO leakage..." very interesting Idea - I never though about it!

[@AndreasSpiess]

@ ats89117: I do not understand what you mean with "DC axis".

[@vk3fbab]

That is how radar detector detectors work. Detecting the very high LO used to demodulate a radar signal. So if you can better shield the LO or use one on a different frequency the police won't detect your radar detector.

[@DouglasEKnappMSAOM]

He said they would be cut off, if you did not use the trick. The trick was to fold or rotate the signal. Not even trying to say that I have a deep understanding of this, I don't.

[@ats89117]

@@DouglasEKnappMSAOM The 'trick' is to sample in quadrature so that the positive and negative frequencies can be separated. In a zero IF system this is essential to being able to distinguish frequencies above and below the mixing frequency.

[@Panakotta000]

I'm now in for about a year in the SDR world (RTL-SDR v3, now upgraded to an SDRplay RSP1B). And I usually tried to understand what is happening, but only tinkering really helped. This video explained it really well how such SDRs are built. Thanks!

[@AndreasSpiess]

Glad I could help!

[@MissingClara]

The LimeSDR has great software support, just like the HackRF One, rtl-sdr and USRP. SoapySDR unifies practically all SDR stacks, making the hardware vendor/driver provider insignificant.

[@AndreasSpiess]

As I do not own one, I have to rely on the opinion of my buddy Frank...

[@MissingClara]

@@AndreasSpiess I understand. Have a look at github.com/pothosware/SoapySDR/wiki :) Software support is surprisingly great across all SDR devices!

[@MissingClara]

@@AndreasSpiess And, by the way, great video! You managed to put the core concepts of SDR and quadrature in way that is easy to understand even for people without much technical background.

[@playingidiot7531]

Oh wow, you answered many questions for me that werent even related to SDR's. Thank You for this great compilation of knowledge.

[@AndreasSpiess]

You are welcome!

[@christopherguy1217]

Wow, you managed to produce an exceptionally good and in depth coverage of this topic even exceeding your usual high quality informative videos we are used to getting, bravo. I bought a couple of the cheap SDR dongles to try but I found myself lost in the sea of information and software and put it aside for later. This video has clarified so much for me that I'm ready to give it another go to see if I can't get it to work for me. My first project will be to determine if the transmitter of my weather instruments is sending a signal and if so to build a replacement receiver to get the weather data displayed again.

[@AndreasSpiess]

Thank you. Maybe you watch my videos about that topic? If your weather station is on 433 MHz

[@L-36]

A long time ago in a land far away I designed I-Q equipment. The 3GHz I-Q based signal generator was the HP8780 and the IQ demodulator and display was the HP8980. I left HP after 21 years and went to a new company where we invented the first Cable Modems. Ultimately my group was bought by a big blue company that messed it all up so 20 years ago I quit. About the same time I became an inactive HAM. Now I am getting back into HAM radio. I just bought a hybrid SDR HAM radio, the FTDX10. The technology has changed so much but seeing your video here was fascinating. It brings back so many memories. I was an early proponent of the I-Q space and it is just mind boggling to see what has happened in the last 20 years. I feel like the mythical man who was on a tropical island for 20 years and returns to find the world has changed. For the last several years I have been designing equipment for my boat using Intel Edison Edison, ESP8266, and ESP32 and have enjoyed your channel for some time but somehow missed this episode until now. Really loved this video. Thank you for making it.

[@AndreasSpiess]

It is an honor to read your comment! Thank you. I also recently got back to HAM radio. With an IC-7300... But I use an Adalm Pluto for my satellite project...

[@Conservator.]

14:50 “a treat especial” Andreas must be watching AvE too.

[@anullhandle]

That's a little worrisome lol. How do you demodulate a mix of Swiss English and Canucistan jabberwocky?

[@publicmail2]

Yea keep your dipole in a vice.

[@publicmail2]

Idk but I like the word jabberwocky

[@Conservator.]

A D errh, di-pole? Idk that configuration personally, only mono-pole

[@AndreasSpiess]

@conservator: Sometimes. Hard to understand for a Swiss guy...

[@HelmutTschemernjak]

Thank you for the overview of the different SDR devices and the basics. I was watching the Ossmann trainings and I am completely convinced that his great stuff. Thank you for bringing it down to 27 minutes for an overview.

[@AndreasSpiess]

I watched them twice at least. He does a great job!

[@dl8cy]

EXCELLENT VIDEO! I'm a little jealous of your Swiss Ham Radio license card - we still carry such an A6 rag in Germany vy 73 de dl8cy 2 u hb9bla

[@AndreasSpiess]

I only got it about 2 years ago. Once we were faster ;-)

[@sundhaug92]

Mike, I think a cat walked on your keyboard

[@dl8cy]

@@sundhaug92 it seems you are not an ham radio amateur - these are morse code abbreviations and every licensed radio amateur have to know these (it's part of the exam)

[@raywelshman]

@@dl8cy Hi Mike, In the UK we don't have to learn CW any more, I passed my amateur radio exam in 1982, I don't use ham radio much now. 73 de GW6IYP Ray in North West Wales.

[@dl8cy]

@@raywelshman same in Germany, but that abbreviation could also used in rtty or ft8 for example

[@andycooper1684]

Outstanding introduction to SDR Andreas. I think you perfectly captured the correct 1% of required facts :-).

[@AndreasSpiess]

Thank you!

[@Argosh]

It's the swiss army. I can guarantee you that there's still some poor soul sitting there scanning frequencies by hand 😁

[@AndreasSpiess]

:-))

[@thearchibaldtuttle]

Pretty sure! There is no shortage on people and time in the Swiss army! Ruhn, abtreten!

[@peettims6569]

The old gear has a place. The history is awesome with rigs like the Collins and halicrafters. Yes new sdr is amazing and can work way better than old tube radios but if you had one tube radio and a few spare parts you could fix it. Sdr rigs are the definitely better but the old rigs are great. A good Collins 75s3b

[@ikokovidis56]

Congratulations Dr,Andreas...Never had a so comprehensive explanation of the SDRs we use..Keep up the good work!! 73 de SV2LLJ Ioannis

[@AndreasSpiess]

I am glad you liked it! 73 de HB9BLA

[@TheAcujlGamer]

I'm now building a radiotelescope but just stared my journey on SDR-RTL a few months ago

[@AndreasSpiess]

Great plan. I hope you will be successful!

[@williambudd2850]

A friend suggested that I learn the 60 to 80 abbreviations used in SDR menus as a way to get started with using SDR’s. I thanked him for the warning and pointed out that I have better things to do with my time and if a SDR is not intuitive and easy to use, I don’t want one. Such a suggestion is appropriate because during my time working as an electronic engineer, I learned that programmers could turn an intutive concept into somethng no one can understand in no time at all !!!

[@AndreasSpiess]

You probably already use SDR technology in some of your devices without knowing it ;-) Which would be what you suggest. Often increased possibilities also imply increased complexity.

[@rfmonkey4942]

Use sdr at work and home it's The greatest thing since sliced bread and BMW deisel with 4 turbos

[@AndreasSpiess]

:-))

[@TheMvieira]

Great Class Andreas!!!! Really cool video!!! I ordered one RTL SDR to help me on site survey for LoRa TXs. Thank you for sharing your knowledge!

[@AndreasSpiess]

Lora will not be easy because the protocol still is proprietary :-(

[@mikedavis1426]

Awesome job -- thanks for the links and inspiration! This old man is going to learn some higher math and all about I/Q signals!!!!

[@AndreasSpiess]

Old man here, too (62) ;-)

[@mohsinhijazee2008]

Very impressive! You're a talented teacher in capturing and ordering concepts into bins. Too good! I think it's the best orientation video on SDR out there.

[@AndreasSpiess]

Thank you for your nice words!

[@foxabilo]

If passively listening to something is illegal then the entire world has gone mad.

[@AndreasSpiess]

Maybe you are right. But in many countries it is the law.

[@NiHaoMike64]

He's referring to eavesdropping/spying laws.

[@foxabilo]

@eric thefathead Well, I am going to make the colour blue illegal to see, I am going to transmit highly confidential information using blue light. Absolute poppycock. If a publicly available signal is criminal to receive then the broadcaster is guilty of willful entrapment. I understand that splicing into a telephone line is an active form of spying and a privacy violation. BUT... mearly having a receiver able to receive many frequencies and one of those frequencies being protected is the ramblings of an authoritarian dictatorship gone mad.

[@NiHaoMike64]

@eric thefathead For the most part, in the US, you can receive whatever you want but what you do with the information is restricted. Part of that includes restrictions on what can be decrypted, e.g. at one time satellite TV providers had a huge piracy problem and they had to upgrade their systems to encrypt the signal since receiving a signal in the clear was ruled to be perfectly legal, but breaking the encryption wasn't.

[@foxabilo]

@eric thefathead I could say the same for Bluetooth and 1234, routers and admin admin, wifi hotspots with root console on RS232 TX/RX, the industry never learns.

[@DougHanchard]

Excellent. Andreas should be hired by "Masterclass". With this video, amateur radio and aviation enthusiast should now be able to understand how Flight Tracker had made a business using SDR.

[@AndreasSpiess]

Thank you! I think, youtube is a very good platform to learn. At least for me...

[@StephanEdelman]

I think you mean 100KHz, not 1KHz at 21:13

[@AndreasSpiess]

Yes

[@georgelewisray]

WOW , WONDERFUL :: You have exceeded your usual very high standard and created a overview/documentation/teaching document that is of great value to the digital maker world. HOORAY!!!! ( p.s. many many thanks for pointing out the Mike Ossman video SDR playlist )

[@AndreasSpiess]

Thank you for your nice words!

[@CarstenMeyer]

Did you really compare accustic waves with electro magnetic waves? :-) I am sure my ears cannot hear 10 kHz electro magnetic waves ... :-)

[@AndreasSpiess]

I hardly hear 10kHz acoustic waves anymore ;-)

[@WacKEDmaN]

you can "see" it with SDR tho!..

[@MuscleTeamOfficial]

I am so glad I am getting into this now as opposed to 5+ years ago. There is just sooo much more content about this available to noobs! Thank you for making this!

[@AndreasSpiess]

You are welcome!

[@SignalsEverywhere]

Great video, I would have loved the opportunity to work with you on it. Perhaps we can collaborate on a future video?

[@AndreasSpiess]

I sent you a message

[@Sefton.]

Great video Andreas! I've made nodes for agricultural sensors and have used SDR with the Adafruit Feather 915MHz Hope RFM95 LoRa boards. Cheers from Australia!

[@karlharvymarx2650]

Andreas, you are the first to explain local oscillator and mixer and IQ in a way that made it past my thick skull. Now it seems so simple I'm going to try making a toy SDR with my FPGA to remind myself that I still don't know the other 99% :-)

[@AndreasSpiess]

Good luck! To build one is much harder ;-)

[@rweatherley4437]

Andres - you are a brilliant educator and I learned so much from this video today. Thank you very much for doing this. I intend to purchase an RTL-SDR dongle today and get started with this fascinating technology.

[@AndreasSpiess]

Glad it was helpful! And have fun with it.

[@simonbaxter8001]

Fantastic video. I've been playing with SDR for a while, but you've just explained everything perfectly in 27 minutes. Need to step up from a SDR dongle to a HackRF One now!

[@TheBodgybrothers]

Do it man, you wont regret it!

[@AndreasSpiess]

Enjoy!

[@thirumenip5416]

You are contributing to the technical society and saving our time, which we will be spending otherwise to do the basic research on - learning "Hello World on SDR"

[@AndreasSpiess]

Saving the time of the viewers is one of the main goal of this channel...

[@jkctech]

Been using one of those 10 dollar dongles to receive national emergency services pager messages in the Netherlands for a while now. Best thing I ever found out about. Playing with radio is amazing. Highly recommended

[@AndreasSpiess]

Thank you for sharing your experience!

[@davidtindall196]

Fantastic explanation! I now have a better understanding of I/Q signals. I grew up in the analog age and really found your video helpful.

[@AndreasSpiess]

Glad it was helpful! Your knowledge for sure helped to understand this "new world".

[@pavel9652]

Excellent video! This is the best video on SDR I have seen so far! I had purchased RTL2832U based SDR couple years ago but had no time to experiment until recently. I am glad to see SDR have such great software support on Linux systems!

[@AndreasSpiess]

Thank you!

[@JD_Viddy]

A timely video, I just received a Nooelec SDR receiver and "Ham It Up" up-converter a few days ago. Using it on an old Macbook Pro using the CubicSDR software. Thank you very much from KC1MC.

[@AndreasSpiess]

I hope you enjoy it!

[@matturner6890]

Wow, I'm glad I have experience with audio engineering because it's actually helping me understand this stuff!! It's all just signal processing in the end! Chucking what you don't want, keeping what you do.

[@AndreasSpiess]

Indeed, most of the processing is done on low frequencies!

[@henrikgraversen1943]

WOW, i am blown away ... SDR is new to me (and I'm a electronic/computer engineer 😂) ... Fantastic video ... and i love your Swiss accent 😊

[@AndreasSpiess]

Thank you. Indeed this is a fascinating technology and it will replace the analog radios in a short time.

[@jweismiller]

Hi Andreas, I really enjoy watching your videos. They are all extremely well done. I believe you can simply the explanation of the IQ signals. When you down-convert the signal to 0 HZ, you essentially get a DC level after the low pass filter for any signals that are exactly the same as your intermediate frequency. This level depends on the phase difference between your incoming signal and the IF. If the phase matches exactly, you will get a high level, and if it's out of phase, you will get nothing. Therefore, you can't tell the difference between an out of phase signal and no signal at all. The solution to this is to have another mixer which is 90 degrees out of phase from your primary oscillator. This way the signal will show up on one channel or the other. This also holds true for signals that are some offset from the IF. For example, if the IF is 100Mhz, both a 99.99Mhz and a 100.01Mhz signal will show up as 10Khz signal after mixing. However, these resulting 10Khz signals will have different phases between each other on the I and Q channels. This allows the demodulator to tell the difference.

[@Palmit_]

as a newbie, that explanation isn't any simpler. Thank you tho. I'm sure as i get up to speed with this stuff, it'll make more sense.

[@hugocoolens]

Great video, of course now you have made a lot of persons longing for your version _with_ the complex numbers

[@AndreasSpiess]

This will not happen as Michel did a great job already...

[@hberle]

Excelent video. Been using SDR for a while for AIS and ADS-B reception. A good antenna is important.

[@AndreasSpiess]

You are right. Antennas are always important!

[@dri50]

Probably one of the best descriptions of I/Q that I have seen because you described it in terms of the necessary local oscillator frequency. Don KC3MBK

[@AndreasSpiess]

Thank you!

[@HobbyelektronikerCh]

Vielen Dank für die informative Zusammenfassung. Gerade passend zum kommenden GNU-Radio Seminar der USKA Academy.

[@AndreasSpiess]

Bitte, gern geschehen. Bei diesem Seminar war ich letztes Jahr und habe sehr viel gelernt!

[@centexrails]

Another wonderful video covering the topic. I use an SDR to receive railroad dispatching communication. Works great for the price and size of a cheap dongle

[@AndreasSpiess]

Interesting service. I never heard of it!

[@mikepreece7790]

I love your videos, they are always so informative!! I just got a mid roll ad. I thought I would let you know. It was at 13 minutes.

[@AndreasSpiess]

Yes. Back then I placed one in Videos longer than 20 minutes. And I did not change the old videos

[@tonytor5346]

Thanks!

[@AndreasSpiess]

Thank you for your support!

[@matturner6890]

1:30 what causes those funky distortions in the audio?

[@AndreasSpiess]

They use Single Side Band (SSB) modulation. And usually, we distort the voice to get a better understanding.

[@newburypi]

A POX UPON YOU!!! First you create videos to boost on line purchases of electronic gizmos, and now you add a whole new series of questions and potential projects for aged man in his declining years. But... 😁 Thanks for another informative and well delivered video 👍

[@AndreasSpiess]

Here is also an aged man... You are welcome!

[@nicomedia62]

Great explanation Mr Spiess, I’ve been experimenting with a couple of SDR’s last couple of years, although as an old school engineer which I love analog design; I think future is SDR.

[@AndreasSpiess]

It does not hurt to know about filters in this area, too... (I did not mention it)

[@backacheache]

So given how much modern musicians and concerts love radio microphones, you could make your own recording of them all in one go!

[@joinedupjon]

& see who's faking it with pre-recorded vocals

[@AndreasSpiess]

Maybe the distance between the concerts creates you a headache?

[@TheBodgybrothers]

The hackrf one is the best entry into sdr. I got mine and after a month had a low power linkit 7688 running openwrt doing the work. You dont need Rpi or computers, lower power micros on routers are capable for simple tasks. The hackrf one has all the code open and it cross compiles on openwrt easily. And the video tutorials are the best for beginners. It got me started in a weekend.

[@tommihommi1]

plutosdr > hackrf

[@AndreasSpiess]

Thank you for sharing your experience. It might help somebody without an RPi...

[@tpcdude]

Great video. So many of the SDR boxes are poorly supported and never explained. No where do most suppliers explain what I/Q is and you did that very well. I was early playing around with SDR dongles for use on HAM radio in the USA. It was an exercise in frustration, i probably have 6 different early SDR hunks of hardware with and without up-converters. The software was great if you could still find valid web-links to download it and an "improvement" didn't blow you working system offline. As you look through open source drivers you find comments like "show the driver some love" which is useless to the end users. Thanks for the great video, always buy a SDR that the supplier provides supported software that is tested on the your PC platform with the same version of windows software otherwise you will be doing the suppliers job debugging software til you go mad.

[@AndreasSpiess]

You are right. Software support these days has become very important. And because SDR is a new technology, not all concepts survive and get the needed "love" from the community...

[@CyclingSteve]

Thank you Andreas, a very comprehensive explanation, I'd like to add Pi-FM-RDS. As it allows for a cheap simple test FM signal, it's also a lot of fun for those learning about radio.

[@AndreasSpiess]

Thank you for your addition!

[@mrr2880]

Thanks for the effort put into this video, excellent content.. just started exploring SDR for the purpose of WiFi Spectrum analysis on 2.4GHz, 5GHz & 6-7GHz..

[@AndreasSpiess]

Glad it was helpful!

[@886014]

Fantastic video, thank you for providing this. A lot has changed since I was in the industry!!!

[@AndreasSpiess]

You are right. And I love it!

[@luismirandakunert3475]

What a way to teach and share your knowledge!!! Thank you Andreas!!

[@AndreasSpiess]

My pleasure!

[@springwoodcottage4248]

Outstandingly clear, informative and fascinating. Thank you for sharing in such a useful way.

[@AndreasSpiess]

You are welcome!

[@NicolasP1973]

Great video as usual Andreas! I played a lot with SDR a few years ago. I began with the softrock kits sending the IQ signals to a soundcard for the ADC. This gave a bandwith of only a few kHz. After that I had a RTLsdr and this was a great upgrade. I used it for receiving HAM Radio, boat tracking system, POCsac and also for looking of interferences! 73's de ON8NP

[@AndreasSpiess]

Using a sound card seems to be also interesting. Maybe I try to play with it once.

[@laurentcastella6794]

Who can be better spies than Mr. Spiess. Great video, many thanks Andreas. 73.

[@AndreasSpiess]

You are welcome!

[@hygri]

Andreas, that is a truly excellent overview! Inspired me to get my nooelec rtl out again and play with ADS-B in - thanks!!

[@AndreasSpiess]

You are welcome! Enjoy!

[@solomioist]

17:26 on the board: Why did you choose a Hamming-Window with the Lowpass Filter? Would a eg Blackman Window make more Sense for a more cleaner Signal in respect of harmonics?

[@AndreasSpiess]

Because it was the default, I think. I never cared about these parameters :-(

[@EvanWilliamsofPrinceton]

Thank you for this beautiful summary of Software Defined Radio! See you at GNU Radio 2020!

[@AndreasSpiess]

You are welcome! The GNU Radio conference is probably a little too specialized for me :-(

[@MrGrey-dx5sb]

11:04 this might be a dumb question but I am learning, why not just take the singles and turn them into to double/2 CH so you don't have to use two of each you can use the new 2 channel ones. We could even design them and have a product that could and would take over?

[@AndreasSpiess]

SDRs do not have channels. They cover frequency ranges which, generally cover hundreds or thousands of channels.

[@gprivat812_my_selection6]

Great service to all who want to understand such technologies! 👍🙂❗

[@AndreasSpiess]

Glad you liked it!

[@PlanetObservatory]

I have always been fascinated by radios since I was a kid. First walkies, then cb radio, thenham radio. I need to study up and go upgrade my ham license again. Life always seems to get in the way. SDR, just goes along with my love. Kinda starting to add some ham radio and sdr into my channel with my astronomy stuff. Hopefully I get to build a goes Sat setup before long.

[@AndreasSpiess]

I saw you tried an SDR dongle on the weather satellite. Good start!

[@motherjoon]

God Bless this man for simplifying such complex topics

[@AndreasSpiess]

:-)

[@fotografm]

Lovely overview ! Don't forget that the Aaronia SDR receivers with amazing performance are now becoming affordable 🙂

[@AndreasSpiess]

I do not forget about them (I own a Spectran V6 ;-)

[@fotografm]

@@AndreasSpiess No surprises there LOL

[@BarefootBeekeeper]

Currently experimenting with SDR on Linux and Android, using mainly CubicSDR and SDR Touch respectively. Antennas are a critical component, as usual with radio, and I plan to take the kit into the wild with a variety of wires, whips and loops. Videos may follow...

[@AndreasSpiess]

SDRs are only different radios. They cannot change physics ;-)

[@ivanovmariscal1457]

This video brings down a lot of dark veils of RF. Awesome, thanks for sharing with the noobs!

[@AndreasSpiess]

I hoped to bring some light into the matter ;-)

[@techydiy]

Thanks, you reminded me to revalidate my license.

[@AndreasSpiess]

Good Idea!

[@levitezer]

Excellent delivery of relevant information!

[@AndreasSpiess]

Glad you think so!

[@JohnOverstreet]

Thank you SO MUCH for this great summary! I'm just getting into SDRs and you gave me a lot of resources.

[@AndreasSpiess]

You are welcome!

[@MalagasOnFire]

Outstanding :D I have bought one DVB USB in 2010 when it was being anounced here the TDT instalation, . Have to check if it is compliant. Model is based on Dibcom STK7070P. Thanks for this hard work ( edit)

[@AndreasSpiess]

9 years is a long time ;-)

[@MalagasOnFire]

@@AndreasSpiess Less time for waiting to the new album from Tool :D The DVB still works as DVB...

[@ksmith7122]

Fantastic well thought out video that will save many ppl a lot of time. I learnt a lot even though I've been using RTL-SDR for sniffing my sensor signals for some time. Very good round out information. Thank you :) :)

[@AndreasSpiess]

You are welcome. Glad you liked it!

[@dimmoos757]

Please make a video about encoding & encryption digital modulations. Your videos are comprehensive and informative. thanks alot .

[@AndreasSpiess]

I have no knowhow in cryptography. So I am not the right guy for that task :-(

[@FreeCircuitLab]

Can we use the frequency mixing technique to increase bandwidth of oscilloscope? Pls reply

[@AndreasSpiess]

Unfortunately no.

[@FreeCircuitLab]

@@AndreasSpiess so please make the first tutorial how to use a raspberry pi pico as an oscilloscope, it has faster ADC and can give best performance among other well available MCU s, there is no tutorial about this yet.

[@AndreasSpiess]

Microcontrollers do not make good oscilloscopes. They are way to to slow. So somebody else has to create such a video.

[@WacKEDmaN]

Excellent SDR Guide Andreas!.. one thing you should have mentioned... antenna is KING!!..without the correct antenna to cover the frequency youre gonna be in a world of hurt! i run a rasberry pi with RTL based SDR for ADSB feed..aswell as a few cheap dongles for scanning the airwaves... Ive listened to Australian World Rally Championship comms last year (around 160Mhz)..aswell as local 2m ham repeater.. fire and rescue (and police before they went encrypted!)..and UHF CB radio.. Ive decoded APRS on 2m aswell as some ACARS messages.. pagers..433Mhz ..and others with TV antenna... Listened to 80m and 40m HF ham radio..decoded HF weatherfax..newsfaxs - Kyodo news from Japan on a single peice of wire about 25m long!. .ive pritty much covered everything i can with 2.8Mhz max bandwith and limitations of the RTL-SDR based dongles - except for satelites i dont have the 'space' for that, or the antennas/dishes required.. i was really hoping you would show us how to build a SDR with an arduino...hint: esp32 with its dual ADC/DACs! :P

[@AndreasSpiess]

You are right with the antennas (I think I mentioned this fact in other videos). Concerning ESP32: You cannot expect a video about that as my skills as well as the capabilities of an ESP32 would be way too limited for a decent application.

[@colinmartin2974]

GREAT STUFF. I can't wait to get on the 100 sat, f5vhz, i really love the simplicity of the sdr concept, and its uses for spectrum monitoring. And decoding possibilities for dtmf coding etc. I want to build a high power small dish rig for static mobile and have one setup on a van roof for mobile operation. So yet another project for me when i leave hospital.. Thanks for the excellent info. Colin f5vhz

[@AndreasSpiess]

Good luck with your project. Maybe you know that I did a video series about the QO-100... 73 de HB9BLA and get well soon!

[@dhanuskodytech4458]

Yes Sir , Thanks for learn about signals. Keep it up 👍

[@AndreasSpiess]

You are welcome!

[@dhanuskodytech4458]

@@AndreasSpiess 😄

[@AdamosDad]

I have the Nooelec NESDR that I use with a Ham It Up Upconverter, also my Xiegue G90 is an SDR transceiver. I love the compactness and ease of use with a computer and the waterfall interface is addictive.

[@AndreasSpiess]

You are right, most of the current receivers are SDRs. That was one reasons for this video.