Historical errata for Explore Software Defined Radio

I haven’t started the book yet (only bought it yesterday), but I’m glad to see it.

One suggestion is that a section on receiving and displaying ADS-B data might make the book attractive to aviation enthusiasts too.

More feedback once I’ve got stuck in.

Link to transportation.gov goes to home page - which image is the text referring to?

Regarding Graham’s question above, it might be worth making clear that you’re referring to the image on page 12, and include the full link (…transportation.gov/sites/dot.gov/files/docs/pnt/286196/electromagnetic-spectrum.pdf) as a footnote.

Somewhere early on, it might be worth mentioning zero-cost options, such as using SERs (Someone Else’s Radio) aka WebSDRs.

For example, a large list of web-connected SDRs can be found at sdr.hu. Many of these seem to be KiwiSDRs, whose UI has a lot of nice features such as decoders for various modes like Fax, RTTY, etc. (BTW, I don’t have any connection with the company, nor do I own one of these, though I am considering it.)

If you’re guiding people towards using dongles (a good way to start!) it might a sidebar to mention that some unscrupulous vendors sell forgeries with poor performance. Got bitten myself by this one a few months ago. See for example www.rtl-sdr.com/genuine/

“or even sound” is misleading. I understand what you mean, but it doesn’t sound correct. Sound is a pressure wave in the air, not EM. Maybe say something like “a signal that would be converted to sound by a speaker”. Or maybe just leave it out completely.

Explain units (e.g. m/s) as many US readers won’t understand. Also explain metric prefixes (M=mega=10e6 etc.)

show calculation: 3 * 10e8 m/s / 100 * 10e6 Hz = 3m

In the introduction, you might consider mentioning higher-end SDR receivers and transceivers, such as SDRplay ( www.sdrplay.com/products/ ) and Flex transceivers ( www.flexradio.com ). These offer bandpass filters, higher sampling rates, and bit depth. There is some amazing equipment available if money is no object.

“They’re both just different frequencies of EM waves. Higher, faster frequencies may manifest as visible light; lower frequencies can manifest as television signals, radio signals, or even sound.” Because you have been talking about RF, it is probably a bad idea to mention sound waves without saying that sound is fundamentally a different kind of wave. Someone who isn’t paying careful attention might think that sound propagates in the same way as TV signals.

“And second, since it avoids the necessary physical imperfections of analog transmitters, more of the power you put into the broadcast gets translated into the signal rather than into heat energy loss in the broadcast equipment.” I don’t believe this is strictly correct. Digital signals often perform better under lower SNR (Signal to Noise Ratio) because of FEC (Forward Error Correction), Spread Spectrum, and other techniques. The heat generated in the RF equipment has more to do with the efficiency of the amplifier at a given frequency and not the underlying signal.

“While software exists to decrypt these signals, it’s often illegal for civilians to use. In other words, stick to your local police department broadcasts and stay away from broadcasts by the NSA or the CIA.” You may want to mention that it is permissible and fun to find and listen to number stations. See en.wikipedia.org/wiki/Numbers_station and lifehacker.com/how-to-listen-to-real-spy-broadcasts-right-now-5961035 .

Running ‘rtl_test’ gives me the following output:
“No supported devices found.”
If this is expected as long as no USB dongle was installed, can you please mention if this is a valid output?

Because of that, I installed rtl_test manually, according to you instructions: same results, no supported device found.

Regards cmake, I suggest to replace these two commands
$ make
$ sudo make install
with these two, which are more generic and work if a different generator is used (e.g -G Ninja):
$ cmake —build .
$ sudo cmake —build . —target install

“Since all electromagnetic waves travel at the speed of light in a vacuum, or 3x108 m/s, the frequency of the pulses distinguishes one type of wave from another. ”

Remove “in a vacuum.” Electromagnetic waves travel at the speed of light in whatever medium they are in. The speed of light, and thus the speed of electromagnetic waves, is slightly less in air.

Chapter title: Listening to Satelites