docs: add supported hardware document

resolves #23.

docs/7.supported-hardware.md

@@ -0,0 +1,66 @@
+# Supported Hardware
+
+## Hardware SDR Sources and Sinks
+
+Hardware SDRs source and sink digital I/Q samples through USB, PCI, or other
+high speed digital interfaces.
+
+### Sources
+
+* [RTL-SDR](http://www.rtl-sdr.com/about-rtl-sdr/) with [`RtlSdrSource`](0.reference-manual.md#rtlsdrsource) via [librtlsdr](http://sdr.osmocom.org/trac/wiki/rtl-sdr)
+* [Airspy R2 and Mini](http://airspy.com/) with [`AirspySource`](0.reference-manual.md#airspysource) via [libairspy](https://github.com/airspy/host)
+* [HackRF One](https://greatscottgadgets.com/hackrf/) with [`HackRFSource`](0.reference-manual.md#hackrfsource) via [libhackrf](https://github.com/mossmann/hackrf)
+* [SDRplay RSP](http://sdrplay.com/) with [`SDRplaySource`](0.reference-manual.md#sdrplaysource) via [libmirsdrapi-rsp](http://sdrplay.com/linux.html)
+
+Coming soon:
+
+* [SoapySDR modules](https://github.com/pothosware/SoapySDR/wiki) with `SoapySDRSource` via [libSoapySDR](https://github.com/pothosware/SoapySDR)
+* [BladeRF](http://nuand.com/) with [`BladeRFSource`](https://github.com/vsergeev/luaradio/issues/19) via [libbladerf](https://github.com/Nuand/bladeRF)
+
+### Sinks
+
+None to date.
+
+Coming soon:
+
+* [HackRF One](https://greatscottgadgets.com/hackrf/) with `HackRFSink` via [libhackrf](https://github.com/mossmann/hackrf)
+* [SoapySDR modules](https://github.com/pothosware/SoapySDR/wiki) with `SoapySDRSink` via [libSoapySDR](https://github.com/pothosware/SoapySDR)
+* [BladeRF](http://nuand.com/) with `BladeRFSink` via [libbladerf](https://github.com/Nuand/bladeRF)
+
+## Sound card SDR Sources and Sinks
+
+Sound card SDRs, like the [SoftRock](http://fivedash.com/) or
+[SignaLink](http://www.tigertronics.com/), source and sink analog I/Q signals
+through sound card stereo line-in and line-out interfaces.
+
+### Sources
+
+None to date.
+
+Coming soon:
+
+* `PulseAudioSource` via [libpulse](https://freedesktop.org/software/pulseaudio/doxygen/)
+
+### Sinks
+
+* [`PulseAudioSink`](0.reference-manual.md#pulseaudiosink) via [libpulse](https://freedesktop.org/software/pulseaudio/doxygen/)
+* [`PortAudioSink`](0.reference-manual.md#portaudiosink) via [libportaudio](http://www.portaudio.com/)
+
+## File Sources and Sinks
+
+File sources and sinks can also indirectly support SDR hardware by reading or
+writing a named pipe, linked to an external utility that interfaces with the
+SDR hardware.
+
+### Sources
+
+* [`IQFileSource`](0.reference-manual.md#iqfilesource) for binary I/Q files
+* [`RealFileSource`](0.reference-manual.md#realfilesource) for binary real-valued files
+* [`WAVFileSource`](0.reference-manual.md#wavfilesource) for WAV files
+
+### Sinks
+
+* [`IQFileSink`](0.reference-manual.md#iqfilesink) for binary I/Q files
+* [`RealFileSink`](0.reference-manual.md#realfilesink) for binary real-valued files
+* [`WAVFileSink`](0.reference-manual.md#wavfilesink) for WAV files
+