SDR -- And Why Its Future Looks Bright
A software-defined radio (SDR) is a radio implemented with reconfigurable software, which processes the raw samples of a digitized radio signal. This contrasts with conventional hardware radios, which employ RF circuits and digital signal processors to implement this processing. Because much of the functionality is implemented in software running on a PC and not hardware circuitry, then SDRs typically cost much less. A software-defined radio still requires some hardware, but this hardware is relegated to just receiving and transmitting radio signals. An SDR system consists of a low-cost receiver and a host computer running software that performs data acquisition and analysis, along with a graphical display.
HackRF is a SDR peripheral capable of reception (or transmission) of radio signals from 1MHz to 6GHz. Designed to enable test and development of modern and next generation radio technologies, when combined with the right software -- such as Rational Waves -- it can be used as a near real-time RF spectrum analyzer for a wide range of wireless applications. With
excellent performance at a cost < $350 USD, it has become one of our favorites for RF diagnostics -- especially since it supports such a wide frequency range that includes UHF frequencies used by wireless pro audio and both 2.4x GHz and 5.x GHz Wi-Fi bands.
Why Rational Waves?
An inherent feature that often goes unheralded is Rational Waves' ability to bring wide-band, fine resolution spectrum scans to devices that are otherwise limited by bandwidth or number of data points per scan. HackRF devices are limited by small bandwidth (approx. 20 MHz). By "stitching together" many subscans the software can display wide band (up to 300 MHz) scans with fine resolution, allowing HackRF receivers to be used as near, real-time RF spectrum analyzers. This is the primary value the software brings to the table. In addtion, Rational Waves supports a variety of different RF analyzers and displays data using several types of graphical charts, which help reveal patterns or events in the spectrum data that might otherwise go unnoticed.
A SDR receiver is defined by three basic specifications: bandwidth, resolution, and tuning range. Bandwidth is the instantaneous width of frequency content that the SDR receiver can receive. It can be thought of as the width of the SDR’s window into the RF spectrum. Resolution refers to the receiver's ability to distinguish between adjacent signals. If the resolution is too course then adjacent peaks may appear as one. And tuning range is the frequency range that the SDR receiver can tune to -- which is very specific to the receiver's hardware. For example, an AM radio can not receive FM signals and vice-versa.
For RF spectrum analysis, all three specification are important. If bandwidth is too narrow, then you can't scan a wide frequency range such as UHF or Wi-Fi. And if resolution is too course then you can't tell whether a peak is a single transmitter or two adjacent ones. And the tuning range must match with the frequency range you wish to monitor. The HackRF has amazing performance and resolution that when combined with Rational Waves software provides an excellent diagnostic tool for troubleshooting a wide range of RF issues -- including wireless pro audio and both the 2.4x and 5.x GHz Wi-Fi bands.
A Google search for "Buy HackRF" will yield many results that range in price around $300 - $375 USD, depending on accessories. For the best selection, prices, shipping options and after purchase support our favorite source is NooElec.