Editing Software-defined radio (section)

== Amateur and home use ==
[[File:Perseus SDR receiver.jpg|thumb|right|Microtelecom Perseus – an HF SDR for the amateur radio market]]
A typical [[amateur radio|amateur]] software radio uses a [[direct conversion receiver]]. Unlike direct conversion receivers of the more distant past, the mixer technologies used are based on the quadrature sampling detector and the quadrature sampling exciter.<ref>{{Citation |last=Youngblood |first=Gerald |title=A Software Defined Radio for the Masses, Part 1 |journal=[[QEX]] |pages=1–9 |publisher=[[American Radio Relay League]] |date=July 2002 |url=https://www.arrl.org/files/file/Technology/tis/info/pdf/020708qex013.pdf }}</ref><ref>{{Citation |last=Youngblood |first=Gerald |title=A Software Defined Radio for the Masses, Part 2 |journal=[[QEX]] |pages=10–18 |publisher=[[American Radio Relay League]] |date=Sep–Oct 2002 |url=http://www.arrl.org/files/file/Technology/tis/info/pdf/020910qex010.pdf }}</ref><ref>{{Citation |last=Youngblood |first=Gerald |title=A Software Defined Radio for the Masses, Part 3 |journal=[[QEX]] |pages=1–10 |publisher=[[American Radio Relay League]] |date=Nov–Dec 2002 |url=http://www.arrl.org/files/file/Technology/tis/info/pdf/021112qex027.pdf }}</ref><ref>{{Citation |last=Youngblood |first=Gerald |title=A Software Defined Radio for the Masses, Part 4 |journal=[[QEX]] |pages=20–31 |publisher=[[American Radio Relay League]] |date=Mar–Apr 2003 |url=http://www.arrl.org/files/file/Technology/tis/info/pdf/030304qex020.pdf }}</ref>

The receiver performance of this line of SDRs is directly related to the dynamic range of the analog-to-digital converters (ADCs) utilized.<ref>{{cite magazine|author=Rick Lindquist|author2=Joel R. Hailas |url=http://www.redorbit.com/news/technology/258812/flexradio_systems_sdr1000_hfvhf_software_defined_radio_redux/index.html|title=FlexRadio Systems; SDR-1000 HF+VHF Software Defined Radio Redux|magazine=[[QST]]|date=October 2005 |access-date=2008-12-07}}</ref>  Radio frequency signals are down converted to the audio frequency band, which is sampled by a high performance audio frequency ADC. First generation SDRs used a 44&nbsp;kHz PC sound card to provide [[Analog-to-digital converter|ADC]] functionality. The newer software defined radios use embedded high performance ADCs that provide higher [[dynamic range]] and are more resistant to noise and RF interference.

A fast PC performs the [[digital signal processing]] (DSP) operations using software specific for the radio hardware.  Several software radio implementations use the open source SDR library DttSP.<ref>[http://dttsp.sourceforge.net/ DttSP on Source Forge]</ref>

The SDR software performs all of the demodulation, filtering (both radio frequency and audio frequency), and signal enhancement (equalization and binaural presentation).  Uses include every common amateur modulation: [[morse code]], [[single-sideband modulation]], [[frequency modulation]], [[amplitude modulation]], and a variety of digital modes such as [[radioteletype]], [[slow-scan television]], and [[packet radio]].<ref>http://sourceforge.net/projects/sdr Open source SDR transceiver project using USRP and GNU Radio</ref> Amateurs also experiment with new modulation methods: for instance, the [[Digital Radio Mondiale#DRM software|DREAM]] [[Open-source software|open-source]] project decodes the [[COFDM]] technique used by [[Digital Radio Mondiale]].

There is a broad range of hardware solutions for radio amateurs and home use. There are professional-grade transceiver solutions, e.g. the Zeus ZS-1<ref>[http://zs-1.ru ZS-1 Project]</ref><ref>[http://www.radioaficion.com/HamNews/articles/9483-zeus-zs-1-sdr-transceiver.html ZS-1 Zeus Transceiver]</ref> or FlexRadio,<ref>Flex Radio SDR Transceivers http://www.flex-radio.com/</ref> home-brew solutions, e.g. PicAStar transceiver, the SoftRock SDR kit,<ref>SoftRock SDR Kits http://wb5rvz.com/sdr/</ref> and starter or professional receiver solutions, e.g. the FiFi SDR<ref>FiFi SDR Receiver http://o28.sischa.net/fifisdr/trac</ref> for shortwave, or the Quadrus coherent multi-channel SDR receiver<ref>[http://spectrafold.com/quadrus Quadrus coherenet multi-channel SDR receiver]</ref> for short wave or VHF/UHF in direct digital mode of operation.

=== RTL-SDR ===
[[File:DVB-T USB dongle with RTL2832U and R820T.jpg|thumb|Internals of a low-cost [[DVB-T]] USB dongle that uses Realtek RTL2832U (square IC on the right) as the controller and Rafael Micro R820T (square IC on the left) as the tuner]]

Eric Fry discovered that some common low-cost [[DVB-T]] USB dongles with the Realtek RTL2832U<ref>Using DVB USB Stick as SDR Receiver http://sdr.osmocom.org/trac/wiki/rtl-sdr</ref><ref>RTL-SDR Blog http://www.rtl-sdr.com</ref> controller and tuner, e.g. the Elonics E4000 or the Rafael Micro R820T,<ref>Support for the Rafael Micro R820T tuner in Cocoa Radio https://housedillon.com/blog/support-for-the-rafael-micro-r820t-tuner-o-cocoa-radio/</ref> can be used as a wide-band (3&nbsp;MHz) SDR receiver. Experiments proved the capability of this setup to analyze [[Perseids|Perseids meteor shower]] using [[Graves (system)|Graves radar]] signals.<ref>{{cite web|url=http://www.eb3frn.net/?p=141|title=Perseids shower using graves radar|work=EB3FRN|date=7 October 2013 }}</ref> This project is being maintained by the [[Osmocom]] project.

=== HPSDR ===
The [[HPSDR]] (High Performance Software Defined Radio) project uses  a 16-bit {{nowrap|135 MSPS}} analog-to-digital converter that provides performance over the range 0 to {{nowrap|55 MHz}} comparable to that of a conventional analogue HF radio. The receiver will also operate in the VHF and UHF range using either mixer image or alias responses. Interface to a PC is provided by a [[Universal Serial Bus|USB]] 2.0 interface, although [[Ethernet]] could be used as well.  The project is modular and comprises a [[backplane]] onto which other boards plug in. This allows experimentation with new techniques and devices without the need to replace the entire set of boards. An [[Transmitter#Power output|exciter]] provides {{nowrap|1/2 W}} of RF over the same range or into the VHF and UHF range using image or alias outputs.<ref name="hpsdrhomepage">{{cite web|url=http://openhpsdr.org/ | title=HPSDR Web Site}}</ref>

=== WebSDR ===
WebSDR<ref>WebSDR http://websdr.org</ref> is a project initiated by Pieter-Tjerk de Boer providing access via browser to multiple SDR receivers worldwide covering the complete shortwave spectrum. De Boer has analyzed [[Chirp Transmitter]] signals using the coupled system of receivers.<ref>Chirp Signals analyzed using SDR http://websdr.ewi.utwente.nl:8901/chirps/</ref>

=== KiwiSDR ===
KiwiSDR<ref>{{Cite web |title=KiwiSDR |url=http://www.kiwisdr.com }}</ref> is also a via-browser SDR like WebSDR. Unlike WebSDR, the frequency is limited to 3 Hz to 30 MHz ([[Extremely low frequency|ELF]] to [[High frequency|HF]])