Review: SDR Hands-on Book

Author Burkhard Kainka’s inspiring Foreword in the book I’m reviewing here has important clues as to why software defined radio (SDR) is a hit not only among existing radio amateurs. SDR has proven to be a great promotion tool for the declining radio hobby in general. Since the tuning and decoding of shortwave radio signals is now done with a minimum of hardware and powerful (free) software, it’s easy to see why newcomers to the radio hobby and others with “DC minds” or with “deep fears of RF” have been totally captured by the concept of SDR.

How do you receive RF signals like FM radio or traditional broadcast television? Since this is Elektor it’s much more interesting to use a dipole antenna instead of a dedicated wire connection like cable or the Internet. A dipole antenna works by generating small amounts of current in the presence of an electric RF field which is then sent to the receiver using two-wire conductor called twin lead cable which is a balanced antenna cable. Let’s take a look at what makes this cable so special.

A Raspberry Pi plus a homebrew HAT with driver software and a custom graphical user interface created especially for this application combine to make a unique FM radio that is not only eye-catching but a fascinating learning experience, thanks to extensively detailed documentation. Nobody can fail to learn something new from this wide-ranging project!

According to the US National Toxicology Program, radiation emitted by cellphones is safe for humans, according to recent studies in rats and mice...

Antennas are back magic to many electronicists and to hear that antennas may detune in the presence of metal is a further argument to leave all that “RF wizardry” to the specialists. And you can, safely. Antenova, winner of an Elektra 2017 award, can now supply a 2.4-GHz antenna which is designed to operate without de-tuning on metal surfaces or where the product housing is mainly metal. The antennas from the ‘Reflector’ range consist of two layers, one electrically isolated from the other, so as to provide RF shielding to the second layer. As a result the antenna can be placed on any kind of material and it will radiate effectively in the direction pointing away from the base material.

With this project you can listen to any online radio station, without forking out on a dedicated Internet radio.

The German Amateur Radio Club (DARC) has issued a press release identifying domestic LED light bulbs as a source of electrical interference. The increasing popularity of these light sources has led to a significant increase in reports of radio traffic disturbance, interruption of radio services and even poor DAB reception. In their opinion, the electrically noisy LED lamps are a result of a bad government policy which simply ignores regulations applicable to EMC and the generation of EMI by electrical equipment...

Transmitting data from a capsule dangling from a weather or sounding balloon is not easy as it often involves expensive and sophisticated equipment. Luckily, cheap alternatives exist. This project together with a standard radio transmitter and GPS receiver can be used to beam down up to six analog signals and position data from a balloon, and all of that at very low cost.

Radio reception on AM, shortwave and amateur radio bands stands or falls by the quality of the antenna used. Good results are easy: you just take a wire 30 meters long and string it ten meters above ground between two trees, as far as possible away from your house. In reality this is not always achievable. So we need to find the ideal compromise: an antenna that is effective, unobtrusive — and small.

Dazzled by IoT Bluetooth Low Energy (BLE) and stuff we might overlook the license-free UHF industrial, scientific and medical (ISM) radio bands (433 MHz, 869 MHz and 916 MHz). Like BLE these bands are intended for low-power, low speed data transfers, but unlike BLE there is no standardized communication protocol, everyone can make up his or her own. Also unlike BLE, ISM can have serious range. This project shows how to use these radio bands to setup a wireless datalink with a range of 10 km (line of sight).