The theme of the diploma thesis is the design of the software-defined radio in LabVIEW. On the begining, software defined radio architecture is reviewed. Corelation between various parameters and system hardware is highlighted. USRP can be used in several ways, depending on the needs and knowledge of the user. Each of the ways is presented to the user to get a sense what are the advantages of a single regime of use. The mode, where USRP is used as a computer periphery, is highlighted, because this is the mode, which is used for all the examples in this thesis.
USRP specifications are given to the user to get feeling, what are the limitations of use and which frequency bands and bandwidths can be used for measurements and applications. Detailed review of NI USRP devices is followed by a computer preparation, which includes explanations about LabVIEW programming environment, NI USRP driver and usable add-ons and toolkits.
After that the first practical examples follows. On a basic transmitter and receiver examples, connection with hardware, system parameters configuration, fetching and writing data to NI USR is explained. First examples show code for finite data acqusition, which is later upgraded by countinous execution and signal processing like FFT to get spectrum of acquired signal. When signal processing is introduced, advanced programming architectures are shown to speed up program execution.
After that, example for verifiying the dynamic range of programmabe output amplifier is represented. All examples till now included system parameter configuration before program is run. After this example, examples includes dynamic system parameter configuration, which means, that parameter scan be changed during operation. Dynamic parameter configuration allow us to change central frequency and bandwidth, which means that we can build wideband spectral analyser for constant spectrum signals.
NI USRP can be used for an analog modulation. Due to the prevalence and large number of radio stations in the UKV band, FM analog modulation is selected. First example shows FM receiver, which can play demodulated signal on a PC loadspeaker. After that, FM transmitter is being build. FM transmitter can transmitt FM modulated sine wave or any other wave in later iterations of the transmitter code. Than FM transmitter is upgraded, to be able to transmitt signal saved in WAV file or to transmit signal, acquired from AUX input of a soud card.
LabVIEW allow us to perform digital modulations and demodulations. In the last chapter, all possible digital modulations are explained. At the end, digital communication system is build to demonstrate usage of PSK modulation for simple one way chat application.