Digital Mode Setup for PowerSDR 1.x by WA5QPZ - Part II

Digital Modes for Flex Radio, Part 1

QEX: A Software Defined Radio for the Masses, Part 4

It has been a pleasure to receive feedback from so many QEX readers that they have been inspired to experiment with software-defined radios (SDRs) through this article series. SDRs truly offer opportunities to reinvigorate experimentation in the service and attract new blood from the ranks of future generations of computer-literate young people.1 It is encouraging to learn that many readers see the opportunity to return to a love of experimentation left behind because of the complexity of modern hardware. With SDRs, the opportunity again exists for the experimenter to achieve results that exceed the performance of existing commercial equipment.

Most respondents indicated an interest in gaining access to a complete SDR hardware solution on which they can experiment in software. Based on this feedback, I have decided to offer the SDR-1000 transceiver described in this article as a semi-assembled, three-board set. The SDR-1000 software will also be made available in open-source form along with support for the GNU Radio project on Linux.2 Table 1 outlines preliminary specifications for the SDR-1000 transceiver. I expect to have the hardware available by the time this article is in print.

More at http://www.arrl.org/tis/info/pdf/030304qex020.pdf

Digital Mode Setup with VAC for PowerSDR 1.x by WA5QPZ - Part I

QEX: A Software-Defined Radio for the Masses, Part 3

Part 11 of this series provided a general description of digital signal processing (DSP) as used in software-defined radios (SDRs) and included an overview of a full-featured radio that uses a PC to perform all DSP and control functions. Part 2 described Visual Basic source code that implements a full-duplex quadrature interface to a PC sound card. As previously described, in-phase(I) and quadrature (Q) signals give the ability to modulate or demodulate virtually any type of signal.

The Tayloe Detector, described in Part 1, is a simple method of converting a modulated RF signal to baseband in quadrature, so that it can be presented to the left and right inputs of a stereo PC sound card for signal processing. The full-duplex DirectX8 interface, described in Part 2, accomplishes the input and output of the sampled quadrature signals. The sound-card interface provides an input buffer array, inBuffer(), and an output buffer array, outBuffer(), through which the DSP code receives the captured signal and then outputs the processed signal data.

More at http://www.arrl.org/tis/info/pdf/021112qex027.pdf

W3JK-Flex-Radio Remote Demo Part 2

QEX: A Software-Defined Radio for the Masses, Part 2

Part 1 gave a general description of digital signal processing (DSP) in software-defined radios (SDRs).1 It also provided an overview of a full-featured radio that uses a personal computer to perform all DSP functions. This article begins design implementation with a complete description of software that provides a full-duplex interface to a standard PC sound card.

To perform the magic of digital signal processing, we must be able to convert a signal from analog to digital and back to analog again. Most amateur experimenters already have this capability in their shacks and many have used it for slow-scan television or the new digital modes like PSK31.

More at http://www.arrl.org/tis/info/pdf/020910qex010.pdf

W3JK-Flex-Radio Remote Demo Part 1

Wikipedia: Software-defined radio

A Software-Defined Radio (SDR) system is a radio communication system where components that have typically been implemented in hardware (i.e. mixers, filters, amplifiers, modulators/demodulators, detectors. etc.) are instead implemented using software on a personal computer or other embedded computing devices. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics are making practical many processes that were once only theoretically possible.

A basic SDR may consist of a computer (PC) 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 done using special-purpose hardware. Such a design produces a radio that can receive and transmit a different form of radio protocol (sometimes referred to as a waveform) just by running different software.

More at http://en.wikipedia.org/wiki/Software_radio

QEX: A Software-Defined Radio for the Masses, Part 1

Acertain convergence occurs when multiple technologies align in time to make possible those things that once were only dreamed. The explosive growth of the Internet starting in 1994 was one of those events. While the Internet had existed for many years in government and education prior to that, its popularity had never crossed over into the general populace because of its slow speed and arcane interface. The development of the Web browser, the rapidly accelerating power and availability of the PC, and the availability of inexpensive and increasingly speedy modems brought about the Internet convergence. Suddenly, it all came together so that the Internet and the worldwide Web joined the everyday lexicon of our society.

A similar convergence is occurring in radio communications through digital signal processing (DSP) software to perform most radio functions at performance levels previously considered unattainable. DSP has now been incorporated into much of amateur radio gear on the market to deliver improved noise-reduction and digital-filtering performance. More recently, there has been a lot of discussion about the emergence of so-called softwaredefined radios (SDRs).

A software-defined radio is characterized by its flexibility: Simply modifying or replacing software programs can completely change its functionality. This allows easy upgrade to new modes and improved performance without the need to replace hardware. An SDR can also be easily modified to accommodate the operating needs of individual applications. There is a distinct difference between a radio that internally uses software for some of its functions and a radio that can be completely redefined in the field through modification of software. The latter is a software-defined radio.

More at http://www.ece.jhu.edu/~cooper/SWRadio/Yblood1.pdf

Flex Radio: Basic Tuning Operations