Wireless electronics are becoming more and more flexible thanks to a relatively new class of radio called the software-defined radio (SDR).  Older, conventional radios of the 19^th and 20^th century used electric components to process wireless signals.  SDRs accomplish the same using software.  This makes SDR extremely reconfigurable and highly versatile.

Perhaps no SDR has left more of an impact on hobbyists and open-source development than the RTL-SDR.  This was the first SDR of its kind to sell for well under the price you might expect for something so capable.  The technology isn’t as refined as more expensive alternatives (we’ll see why below), but the RTL-SDR is still capable of:

• Tuning to around 30 MHz to over 1 GHz (for most tuners)
• Scanning and decoding police and fire digital radio
• Tracking aircraft and sea craft
• Hunting transmitter locations using time difference of arrival (TDOA)
• Receiving images from weather satellites
• Adding entropy to cryptographic processes
• Working with Linux, Mac OS, and Windows operating systems

The RTL-SDR dongles ship from a variety of manufacturers, but they rarely include a print manual.  Until now.  The Hobbyist’s Guide to the RTL-SDR compiles tips and guides on the RTL-SDR from a variety of web sources.  Here, I will be covering the latest paperback edition.  Bear in mind the e-reader versions are quite similar.

Overview

The 4^th edition is split up into named sections.  It’s a bit tricky at times because chapters are not numbered as you would normally see in this sort of genre. 

• The Introduction and “Setting up…” chapters are all about understanding what the RTL-SDR is, how to configure yours and so on.  It also introduces a few software tools such as SDR# and GQRX.
• RTL-SDR Misc. Information deals with the non-ideal behaviors and the operating limits of the RTL-SDR device itself.
• RTL-SDR Improvements and Modifications covers ways to counteract the more persistent problems mentioned in the previous section.  Namely through modifications of the hardware and drivers. This area also introduces a few valuable add-ons like upconverters and so on.

The middle and later chapters of the book are largely application-specific.  If you’re looking for ways to tracking air and sea vehicles, there is a section devoted to that.  If you’re trying to receive weather satellite images, work with trunked radio systems, or perform radio astronomy; there are sections devoted to those as well.

The final full chapter is all about RTL-SDR in a lab setting.  This includes characterizing filters, coaxial cables, antennas, and related phenomena.

Finally, beyond the appendices is something I wish more technical books included: a book change log!  This section covers what has changed since previous revisions of the eBook, and it helps connect the print editions with the many electronic revisions.

Key Take-Aways

One thing that RTL-SDRs never ship with (at least to my knowledge) is an operating manual.  I think this operating manual approach best describes what the text is going for here.  The essential ins and outs of optimizing your SDR build are covered without going into all of the formalities of a university textbook.

A good portion of it is also dedicated to helping the RTL-SDR user optimize his or her build.  For example, there is a section dedicated to getting the most out of the stock antenna.  This antenna normally ships with the RTL-SDR, but it is also considered very limiting without modification.

I’d imagine this text is mostly intended for readers with at least some high school experience who have some background using electrical components.  This would put it roughly at the same difficulty level as books like The ARRL Ham Radio License Manual or the older Now You’re Talking series of amateur radio license training manuals.

In summary, this book does a good job of being what it sets out to be: an easy-to-use reference for hobbyists looking to get the most out of the RTL-SDR.  And it does so in an informal and approachable way.

References

[1]	C. Laufer, The Hobbyist’s Guide to the RTL-SDR: Really Cheap Software Defined Radio 1st Edition, CreateSpace Publishing, 2018.
[2]	L. D. Wolfgang, D. R. Straw, D. G. Reed and J. R. Carman, Now You’re Talking! All You Need to Get Your First Amateur Radio License, 5th ed., American Radio Relay League, 2003.
[3]	ARRL Inc., The ARRL Ham Radio License Manual, ARRL Inc., 2018.

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