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== Software Defined Radio == | == Software Defined Radio == | ||
[[File:Rtl-sdr.jpg|thumb|left|Four RTL-SDR devices, two of them with the popular SMA style brass connectors, used to interface with antenna. Note the writing on pink tape on one citing that device's particular parts-per-million clock offset, referenced by the operator when preparing the device for use.]] | |||
In recent years, Software Defined Radio (SDR) has emerged as a practical and accessible alternative to dedicated hardware radio transceivers and receivers. Software Defined Radio implements a software interface to tunable radio hardware, such that reception and broadcasts can be done and processed entirely in software. This gives great flexibility to the operator, even so far as allowing for them to build their own tuners, signal de-modulators and broadcasting stations. | In recent years, Software Defined Radio (SDR) has emerged as a practical and accessible alternative to dedicated hardware radio transceivers and receivers. Software Defined Radio implements a software interface to tunable radio hardware, such that reception and broadcasts can be done and processed entirely in software. This gives great flexibility to the operator, even so far as allowing for them to build their own tuners, signal de-modulators and broadcasting stations. | ||
Software Defined Radio is a large topic, and will not be covered in depth here. Should the reader be interested in exploring building transceivers in an SDR context, both the BladeRF and HackRF are interesting hardware options to look at. A comprehensive list of SDRs can be found here<ref>https://en.wikipedia.org/wiki/List_of_software-defined_radios</ref>. SDRs are typically interfaced with GNUradio or another software radio programming environment<ref>https://en.wikipedia.org/wiki/GNU_Radio</ref>. Every feature and facet of a modern dedicated hardware transceiver can be implemented in software on a laptop or workstation. | Software Defined Radio is a large topic, and will not be covered in depth here. Should the reader be interested in exploring building transceivers in an SDR context, both the BladeRF and HackRF are interesting hardware options to look at. A comprehensive list of SDRs can be found here<ref>https://en.wikipedia.org/wiki/List_of_software-defined_radios</ref>. SDRs are typically interfaced with GNUradio or another software radio programming environment<ref>https://en.wikipedia.org/wiki/GNU_Radio</ref>. Every feature and facet of a modern dedicated hardware transceiver can be implemented in software on a laptop or workstation. | ||
[[File:Full-wave-loop-listeners.jpg|thumb|right|240px|Radio enthusiasts in Aotearoa New Zealand listening to an AM radio broadcast from Austria, received on a 20M Full Wave Loop wire antenna connected to an RTL-SDR tuned by the GQRX software]] | |||
An inexpensive option for those wishing to build a quality receiver for their long-range antenna project is working with RTL-SDR devices and compatible tuners. RTL-SDR devices are low-cost digital video tuner (DVB-T) USB sticks using the Realtek RTL2832U controller that can be repurposed for receiving a broad spectrum of radio signal<ref>https://www.rtl-sdr.com/</ref>. | |||
Some RTL-SDR models will provide reception from 500 kHz up to 1.75 GHz. For those wishing to work with lower signals, for instance in the MW, an 'upconverter' can be used. A popular upconverter is the Nooelec 'Ham it up'. | |||
The RTL-SDR project is maintained by a radio enthusiast group called Osmocom<ref>https://en.wikipedia.org/wiki/Osmocom</ref>. RTL-SDR drivers exist for GNU/Linux, Windows and OS X, and can be tuned with several different popular interfaces. One of them, which is recommended for beginners, is the cross platform visual tuner and de-modulator GQRX<ref>https://gqrx.dk/</ref>. | The RTL-SDR project is maintained by a radio enthusiast group called Osmocom<ref>https://en.wikipedia.org/wiki/Osmocom</ref>. RTL-SDR drivers exist for GNU/Linux, Windows and OS X, and can be tuned with several different popular interfaces. One of them, which is recommended for beginners, is the cross platform visual tuner and de-modulator GQRX<ref>https://gqrx.dk/</ref>. | ||
When working with RTL-SDR devices it is important to use a reference tone to determine the amount of 'clock shift' (in parts-per-million) that the device in use has, and shift it using your chosen tool before use. This is due to the lower quality of the clock (used to tune) on these devices. They will differ from device to device. | When working with RTL-SDR devices it is important to use a reference tone to determine the amount of 'clock shift' (in parts-per-million) that the device in use has, and shift it using your chosen tool before use. This is due to the lower quality of the clock (used to tune) on these devices. They will differ from device to device. | ||