دانلود کتاب رادیوی نرم‌افزارمحور خودتان را بسازید

Today, it seems no longer possible to employ RF technology without Software Defined Radio (SDR). The elegant abbreviation suggests that communications technology has now also converged into a pure software problem that can be easily mastered with a few mouse clicks. To facilitate an easy start with SDR, there is now an almost unmanageable variety of USB plug-in modules and kits on the market. With its tireless ambition, the Linux community has managed to provide libraries for controlling many of the numerous products—a feat that would otherwise be achieved only by large software companies. Connecting a piece of wire or a telescope antenna to the SMA socket of the newly purchased device is easy, as is the selection of the module from the combo box of a ready-made SDR application. For someone who wants to start analyzing signals immediately (e.g., weather radio sensors from the neighborhood, radio signals from airplanes, satellites, etc.), this procedure is maximally efficient and appropriate. Whether a high sensitivity of the receiver can also be achieved in this way, however, depends on many details. With the purchase of the device, a deeper understanding of the signal chain and its weaknesses is delegated to the developers. When using complex host software, you are also faced with a black box, even though these programs have very sophisticated GUI elements that allow a lot of control. All the sub-disciplines – RF technology, electronic circuit design, and digital signal processing, are tough nuts to crack. The easy start with readily fabricated technology can tempt you to become a consumer, or at best, a critical user of the technology. Then, in the face of the high hurdles, it is not unlikely that you will give up your own ambitions. That would be a pity! If you were always the kind of child who had to unscrew everything, you will find the path taken in this book logical, which starts with the hardware: We are developing a modular concept in which the SDR circuit is broken down into its components. A common complication is the mechanically solid and shielded construction; you cannot simply operate a sensitive RF device as a bare circuit board on a desk, at least not in the long run. For this reason, each module has its own metal housing, which is available at low cost as a mass-produced item. For advertising purposes, the building blocks will be called “RF-Bricks”, in reference to the useful interlocking plastic bricks from some major toy manufacturers.