6. Advantages :-> can serve a wide variety of changing, widely different radio protocols in real time digitally interfacable quickly reconfigurable architecture can be encrypted
7. Areas of application Military communication Mobile phones N.B. - which must serve a wide variety of changing radio protocols in real time
8. Components:-> A Personal Computer A sound Card (or any other analog-to-digital converter) An RF front-end(a tuner maybe)
11. Inside Architecture variable-frequency oscillator, mixer, and filter (to tune the desired signal to a common intermediate frequency or baseband) analog-to-digital converter(for sampling & analog to digital conversion) low-noise amplifier must precede the conversion step (Real analog-to-digital converters lack the dynamic range to pick up sub-microvolt, nanowatt-power radio signals) band-pass filters between the antenna and the amplifier (If spurious signals are present (which is typical), these compete with the desired signals within the amplifier's dynamic range. They may introduce distortion in the desired signals, or may block them completely)
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13. Basically a digital baseband receiver; providing programmable interference cancellation & demodulation for broadband signals, (with thousands of adaptive filter taps, using multiple array processors accessing shared memory)
14. origins in the defence sector since the late 1970s in both the U.S. and Europe
16. One of the first public software radio initiatives was a U.S. military project :-> SpeakEasy
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18. SPEAKeasy phase I 1992 to 1995 a radio for the U.S. Army which could operate from 2 MHz to 2 GHz operate with :-> Ground force radios (frequency-agile VHF, FM, and SINCGARS), Air Force radios (VHF AM) Naval Radios (VHF AM and HF SSB teleprinters) Satellites (microwave QAM)
19. Transmitter DOWNconverter/frequency mixer Antenna Automatic gain control Power amplifier VMEbus PCI bus UP converter Digital signal processors (Texas instruments T40) Analog to Digital converter Analog to digital converter INPUT OUTPUT Receiver
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22. Inside A software architecture identifying standard interfaces for different modules of the radio "radio frequency control" to manage the analog parts of the radio "modem control" for managing resources for modulation and demodulation schemes (FM, AM, SSB, QAM, etc) "waveform processing" modules for performing the modem functions "key processing" and "cryptographic processing“ for managing the cryptographic functions "multimedia" module for voice processing a "human interface" to provide local or remote controls a "routing" module for network services a "control" module to keep it all straight
23. Advantages communicate without a central operating system send messages over the PCI computer bus to each other with a layered protocol As a military project, the radio strongly distinguished "red" (unsecured secret data) and "black" (cryptographically-secured data) time to download a stored FPGA program is around 20 milliseconds(an SDR could change transmission protocols and frequencies in one fiftieth of a second, probably not an intolerable interruption for that task)
25. Joint Tactical Radio System (JTRS) is a program of the US military to produce radios that provide flexible and interoperable communications Uses the SDA based on the Software Communications Architecture Operating Systems used: CORBA on POSIX Example---audio terminals that require support include hand-held, vehicular, airborne and dismounted radios, as well as base-stations (fixed and maritime).
26. Amateur or home use Uses a direct conversion receiver Mixers used are based on the quadrature sampling detector and the quadrature sampling exciter Open source SDR library DttSP for Digital signal processing SDR software performs all of the demodulation, filtering (both radio frequency and audio frequency), 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. Amateurs also experiment with new modulation methods(for instance, the DREAM open-source project decodes the COFDM technique used by Digital Radio Mondiale)
27. The GNU radio a signal processing package, which is distributed under the terms of the GNU General Public License. The goal is to give ordinary software people the ability to 'hack' the electromagnetic spectrum, that is, to understand the radio spectrum and think of clever ways to use it. Uses the Universal Software Radio Peripheral (USRP) a USB 2.0 interface an FPGA high-speed set of analog-to-digital and digital-to-analog converters reconfigurable free software sampling and synthesis bandwidth :- a thousand times that of PC sound cards( enables wideband operation)
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30. Also operate in the VHF and UHF range using either mixer image or alias responses
