Is RTL-SDR useful for learning about SDR? - Page 1
Forum section: electronics / rf-microwave

author: watchmaker
author_rank: Unknown
timestamp: November 13, 2024, 02:31:39 pm
content: I just became aware of this area and it looks interesting. I understand that starting at the building block level has a learning curve.Is this dongle still considered a good entry level platform?THANKS!!

author: A.Z.
author_rank: Super Contributor
timestamp: November 13, 2024, 02:41:29 pm
content: Well, for a start and not willing to sheet out much money, the RTL-SDR is still a good "beginners" unit, sure it's pretty basic and has a number of limitations, but then and again, if it's just to gather a bit of experience it's fine, also since it has a pretty wide community and a bunch of documentation, for example herehttps://www.rtl-sdr.com/rtl-sdr-quick-start-guide/you'll find quite a number of informations, tips and idea, just... avoid "chinese clones" and pick the "original" one, otherwise you may waste your money with a unit which isn't up to the specsThe above being said, keep in mind that WHATEVER SDR you'll pick, it won't work withouth a decent antenna installed in an acceptable way; so don't just focus on the SDR unit, also consider a run of good coax and an antenna, if you're in restricted space, you may go for a "miniwhip" or for an "active loop", but in any case place the antenna OUTSIDE, even if that just means placing it on a balcony or outside a window

author: RoGeorge
author_rank: Super Contributor
timestamp: November 13, 2024, 04:29:56 pm
content: I have one cheap TV tuner (RTL-SDR, mine is RTL 820T2), and it was fun to experiment with it. It was fun to install a few software packages and to see a scrolling spectrum with all the radio stations at once, or to use it with GNU Radio and made my own FM receiver from software blocks, or to receive ADS-B signals from airplane and watch the airplanes moving on a map. Plus you'll have a USB FM radio and USB TV tuner for free.But if you want to learn how (or why) an SDR works at all, you'll have to dig a little with the math, and experiment with much less than a full working SDR, I mean PC simulations.To me, the videos of w2aew were (again) one of the most clear and concise source of info (in terms of understanding by experiment), particularly this one, and particularly the experimental illustration of the IQ concept at minute 7:#170: Basics of IQ Signals and IQ modulation & demodulation - A tutorialw2aewThen, started to tinker with simulations. Python, Octave (like Matlab), GNU Radio, LabVIEW (which meanwhile became free for home use). It was quite a journey, but the main understanding (for me) came from that experiment made by w2aew, a big thank you to him and his YT channel.Then I've even bought myself a dual channel AWG to experiment more (Rigol DG4102). Well, at least that was the excuse to buy one. In reality, I've mostly used PC simulations, or the sound card at best, instead of the two channels AWG.Though, the AWG was a good investment anyway for many other (non SDR) experiments and testing. As for the SDR and related topics, most of the experimenting/understanding came from simulating. I did some LabVIEW with sliders I could handle, not sure if I still have those, at some point I've started to put them in a Hackaday project, but I've abandoned it, nothing spectacular:https://hackaday.io/project/7397-do-a-real-magic-spell-essdeeaarI see now that that project still has an interactive Geogebra tool I've made back then, where you can drag sliders in a webpage, and mix "live" the IQ signals, so nothing to install, no oscilloscope, and no AWG are needed to reproduce the experiment seen in the w2aew's video at minute 7:https://www.geogebra.org/classic/nymqtwncAs a result of the SDR learning journey, as usual, I've accidentally "invented" something, a new type of mixer, a combined digital and analog type, and for the fun of it, called it the "RoGeorge Cell", a name intentionally similar with "Gilbert Cell" (which is a consecrated analog multiplier topology):https://hackaday.io/project/7542-rogeorge-cellTried it in practice and it worked from the first try.Sorry for getting chatty, and for the annoying animated gif.Back to the RTL-SDR, it won't brake the bank, mine was $20 or so. Played with it for a month then lost the interest for it. Used it since then a few more times, as a FM radio (it is sold as a TV/radio USB dongle), so the buying was not a loss. It even has an IR remote. The FM radio is OK, can listen to more than the FM broadcasting stations (listened to the Taxi cab dispatchers, ambulance services, etc.). As a TV receiver, I didn't try, never watch TV.Unless you are a ham that needs specific bands or extra sensitivity, my advice would be to buy the cheapest $10-20 Aliexpress/Ebay RTL-SDR that are now available, and to not go for the expensive many hundreds or thousands SDR models.To fully confess, after buying the RTL-SDR, I did bought a more expensive ADALM PLUTO SDR, a devboard from Analog Devices (it was a promo at about $60 or 80 don't recall). PlutoSDR goes up to 6GHz, and can also generate SDR signals, while the typical RTL-SDR can only receive. PlutoSDR has a Zynq FPGA and runs Linux, quite a capable devboard, but never really used it much.

author: Andy Chee
author_rank: Super Contributor
timestamp: November 13, 2024, 08:50:16 pm
content: RTL-SDR is a good practical receiver for listening. But as a learning tool, it hides a lot of the mechanics under the hood.The Softrock series of radios were soundcard based SDRs that were great for learning the fundamentals. Unfortunately the kits are no longer available, but perhaps you can still learn something from the documentation?https://www.wb5rvz.org/softrock_lite_ii/index?projectId=8https://www.wb5rvz.org/ensemble_rx_ii/index?projectId=16

author: radiolistener
author_rank: Super Contributor
timestamp: November 14, 2024, 07:14:58 am
content: Yes, RTLSDR dongle is the best what you can buy for the price below 200 USD.It cost just 30 USD, but from reception quality point of view it is much better than RSP1 which cost more than 100 USD.But it's better to buy original RTLSDRv3 or RTLSDRv4 blog dongle. RTLSDRv4 is better, especially for shortwave, but it requires a little bit more complicated driver installation which may take some time for newbies.

author: ftg
author_rank: Frequent Contributor
timestamp: November 14, 2024, 08:01:25 am
content: I'll echo others suggestions here.Both that the RTL-SDR Blog's V3 RTL-SDR stick is a good, low cost choice for learning about things and usually supported by more or less all modern SDR programs and frameworks.And as radiolistener said, the newer V4 from the RTL-SDR Blog is better on shortwave, but it requires a never version of the base rtl-sdr driver, so some softwares might not support it fully.So for learning I would suggest the V3, it will just work and do that with more or less all rtl-sdr tutorials.But as Andy Chee said, it does hide some aspects under the hood and that might limits how familiar one gets with the low level hardware aspects of SDR.I started out with the <10eur ebay rtl-sdr sticks were stil la thing and they were much morefunthan the SoftRock I had previously built.So yes, the rtl-sdr dongles are still the best starting platform. Best bang for the buck. Best documentation. Best software availability.