Last Updated on May 11, 2021 by KC7NYR
Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which were once only theoretically possible.
A basic SDR system may consist of a personal computer equipped with a sound card, or other analog-to-digital converter, preceded by some form of RF front end. Significant amounts of signal processing are handed over to the general-purpose processor, rather than being done in special-purpose hardware (electronic circuits). Such a design produces a radio which can receive and transmit widely different radio protocols (sometimes referred to as waveforms) based solely on the software used.
Software radios have significant utility for the military and cell phone services, both of which must serve a wide variety of changing radio protocols in real time.
In the long term, software-defined radios are expected by proponents like the SDRForum (now The Wireless Innovation Forum) to become the dominant technology in radio communications. SDRs, along with software defined antennas are the enablers of the cognitive radio.
A software-defined radio can be flexible enough to avoid the “limited spectrum” assumptions of designers of previous kinds of radios, in one or more ways including:
Spread spectrum and ultrawideband techniques allow several transmitters to transmit in the same place on the same frequency with very little interference, typically combined with one or more error detection and correction techniques to fix all the errors caused by that interference.
Software defined antennas adaptively “lock onto” a directional signal, so that receivers can better reject interference from other directions, allowing it to detect fainter transmissions.
Cognitive radio techniques: each radio measures the spectrum in use and communicates that information to other cooperating radios, so that transmitters can avoid mutual interference by selecting unused frequencies. Alternatively, each radio connects to a geolocation database to obtain information about the spectrum occupancy in its location and, flexibly, adjusts its operating frequency and/or transmit power not to cause interference to other wireless services.
Dynamic transmitter power adjustment, based on information communicated from the receivers, lowering transmit power to the minimum necessary, reducing the near-far problem and reducing interference to others, and extending battery life in portable equipment.
Wireless mesh network where every added radio increases total capacity and reduces the power required at any one node. Each node only transmits loudly enough for the message to hop to the nearest node in that direction, reducing near-far problem and reducing interference to others.
From Wikipedia, the free encyclopedia
1) How to get Started with SDR – Download Skywave Linux
What is Skywave Linux? – A Linux operating system using bleeding-edge technology to robustly access broadcast, utility, military, and amateur radio signals from almost anywhere in the world, including countries with restrictive internet environments. Skywave Linux connects to a large and growing network of state-of-the art software defined radio (SDR) servers, making it possible to experience high performance SDR operation without your own large antennas or on-site radio hardware. See Skywave Linux Page for details.
All you need to do is boot the system on a computer with internet connectivity. Skywave Linux can also operate numerous types of SDR hardware, plugged in or on the local network. Downloading, installing and configuring SDR software can be difficult for many computer users; Skywave Linux eliminates the hassle by including several applications installed, configured, and ready to run.
2) Next you will need a SDR Dongle – Counterfeit Warning – On marketplace sites like eBay/Aliexpress etc, opportunistic sellers are advertising all sorts of RTL-SDR dongles under our brand “RTL-SDR Blog”. The dongles with blue, green or sharp rectangular silver cases with a yellow PCB are not ours. Those dongles use poorer quality components, are designed cheaply, and may not have all the V3 features. We cannot provide support for counterfeits. The best place to purchase RTL-SDR V3 dongles, directly or Amazon.
RTL-SDR Blog brand R820T2 RTL2832U 1PPM TCXO SMA V3 Dongle Only. Click here.
Informational & Project Links
Software Defined Radio – KC7MM
DARS: Distributed Amateur Radio Station
Using SDR dongles with Linux By KC7MM
Using SDR dongles with Linux – Part 2 By KC7MM
Split Station – Involves SDR Solution – Project By KC7MM
SDR-hu – Listen to Web SDR
SDR Cube Transceiver – A self-contained, portable SDR Transceiver. Embedded digital signal processing with a Softrock RF front end. No PC required!
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