Software-Defined Radio for Engineers (2018) [pdf]
analog.com
analog.com
I know almost nothing about actual SDR, but I've got a cheap SDR receiver/antenna inside a glass basement door that receives temp/humidity data from ~10 433Mhz transmitters in various rooms in my house + outbuildings, and a weather station that reports temp/humidity/lignthing strikes/rain amount/wind speed+direction, and lux. All that goes to an influx DB instance, and has a set of graphana dashboards built on top of it. Took me a couple evenings to get set up, and now I've got real time + historical environment data about everything I care about at my house; including high humidity alerts in rooms with dehumidifiers, freeze warnings for a crawl space, and a bunch of other stuff. It has been wildly reliable.
https://www.tindie.com/products/hcxqsgroup/4-nanovna-v2-plus...
LimeSDR are a bit more involved, but like most SDR transceivers still need band-pass filters and power amplifiers to perform well. Works well when combined with a GPS locked 10MHz GPSDO like a BG7TBL. =3
Understanding the frequency domain, why it's useful, and how to get there & back, is like 80% of the puzzle.
Sorry just trying to get more detail out of you and apply it towards some code to make it practical. :)
In one of my favorite YT videos ever he talk about how he design RF PCB. The point of it is kind of like, the field of RF and SDR is incredibly deep and complicated, but at the same time, most filters/mixers/amplifiers and everything else needed for making an SDR are ICs that one can buy from Digikey and put them together (or likely have assembled).
So, not denying how deep SDR can be, but it can also be accessible with enough effort!
Do you get this information from radio waves? would love to know more about your setup.
There are several frequency ranges in the US that are unlicensed for transmission. But don't confuse unlicensed with a lack of rules governing what you are allowed to transmit; how often you can transmit and for how long. Because you can plop a 433MHz transceiver into anything, you want to be careful that you're not clogging up the local airwaves by not knowing to know the rules. Also, most smart meters (near me anyway) operat in this band sending out pulses every so often. They mesh together to relay the data towards a central collector. Thanks to that low frequency, hundreds of meters can be visible at times showing up as tiny chirps all over this area of the spectrum. Unfortunately this also means that some cheap receivers (just looking for any signal on a very specific frequency in that range, can be randomly triggered by this 'noise'. But also, because it's used by utilities, to want to make sure they don't end up having an issue with meter readings because you began running a wifi link over 433MHz.
Such weather stations were really commonplace 20 years ago, I remember my grandparents having a sensor outside and a basic LCD display in the kitchen displaying the outdoor temperature and humidity. These days we want that data digitally on our phones or home assistant so you need a receiver that talks TCP/ip and runs a real os. That's where the SDR comes in to bridge the gap between primitive RF Tech and modern computing. Of course you could also put an esp8266 outdoors, which natively talks wifi, but then you lose range and your battery life goes from years to weeks.
It's open source, and you can just play with your audio ports for starters. Later adding a $40 rtlSDR kit goes a long way. I used mine to build a VOR receiver.
I built a gnu radio flowgraph to receive both and display heading to the VOR.
It's written by one of the GNURadio developers, but it uses NumPy and SciPy instead so you really get a feel for the low-level algorithms. Concepts are well explained and build on each other from module to module.
This newer book focus on the more powerful RFSoC from AMD rather the less powerful but the very popular Adalm Pluto kit by Analog Devices that's being covered in this SDR book.
[1] RFSoC book:
There were a few things in GNU radio which have changed since then (different block names) but with a bit of googling you can figure out how to work around it.
Unfortunately for me, SDR is too much like $dayjob so I lost interest. I already spend 8 hours a day at a computer I cannot be convinced to spend more time at a computer doing SDR as I would much rather being doing stuff outside.
Ham radio on the other hand is like an appliance and so there isn’t any programming necessary.
It's very straight forward, depending on your desired level of difficulty: Do it first using blocks in gnuradio, then redo it with blocks you write yourself.
After that do the same thing, but with digital psk modulation, it has the added difficulty of requiring channel estimation/ equalization.
Anyway, many, many open source implementations exist for this as it's a popular first/early SDR project. All you'll you need is the right keywords - for the US, ATSC, and for Europe, DVB-T2.
I just dug my RTL SDR v4 out of the drawer right before a trip to Florida. Guess this is a sign to get it going.
DVB-T2 and ATSC 3.0 receivers are too difficult and nothing exists for them.
Here's a screenshot where I'm transmitting to myself (GNU Radio also has an ATSC transmitter).
Is that true? RTL-SDR are derived from a chip designed for DVB-T tuners.
https://www.ettus.com/products/
Also the limeSDR are supposed to do this. I had one, it arrived inoperable, I sent it back, never heard from them again. Still a little bitter, because I paid in to the crowdfunding.
And also get free premium accounts on sites like flightradar24 etc.
I do, in fact, have two. Great suggestions, thank you.
Hah. Love that attitude.
This book is embarrassingly awful.
> The Fourier transform is just a different way to describe a signal. For example, investigating the Gibbs phenomenon, which states if you add sine waves at specific frequency/phase/amplitude combinations you can approximate a square wave, can be expressed mathematically as (2.1),...
1. The Gibbs phenomenon doesn't state anything. It can be observed; it exists; it is known; it entails things; it implies things; you can state things about it; but it does not, itself, state anything. It is as mute and voiceless as a nudibranch.
2. What is being described is not the Gibbs phenomenon, but the Fourier transform of a square wave. Now, it is true that the truncated Fourier transform of a square wave does exhibit the Gibbs phenomenon. But so does the truncated Fourier transform of any other function containing discontinuities. It's not specific to square waves.
3. This paragraph starts off trying to ineptly explain what the Fourier transform is (a different way to describe a signal? Different from what?), despite the fact that the previous paragraph provides a different and better explanation which is still not very good, but somehow forgets it was going to do so before getting sidetracked with committing the appalling category errors above on the Gibbs phenomenon.
4. You might reasonably assume that the above paragraph, even if poorly expressed, would be followed by some kind of discussion of what the Gibbs phenomenon is, when it matters, and/or when it arises. You would be disappointed; evidently the authors couldn't remember their undergraduate Signals & Systems courses well enough to remember what the Gibbs phenomenon was.
I had skipped ahead to chapter 2 because I couldn't deal with the mindnumbingly awful crap they stuffed Chapter 1 full of, but it didn't get any better. I have to assume the whole book is this literarily abominable and careless about accuracy.
Analog Devices' apparent choice to promote this book for training material suggests that the company's quality standards are no longer what they historically have been and what allows them to charge such a premium for their parts.
Is there some part of this book that is of passable quality? Please tell me that after some introductory filler chapters they started trying to write coherent sentences? I don't have the heart to check.
To all appearances, the HN comments on this post are both better written and far higher in information density than the book it's ostensibly about.
Alex was my advisor in grad school and I only know him to be honest, hard working and technically sound. I haven’t read this book closely but I’m not convinced that it’s poorly written based on cherry picking one paragraph from it.
I agree that it's mean, and I feel kind of bad about it, but I think the interests of the hundreds of people who are apparently interested in reading a book about software-defined radio outweigh the interests of the four authors to not have their feelings hurt. The problem is not that they've written this colossal pile of garbage; there's nothing wrong with that, and it's often the first step toward writing something worth reading. The problem is that that pile is being promoted (by Analog Devices, no less) as a useful way to learn about software-defined radio.