Pulsed noise analysis system

Summary form only given. NRL studies of various microwave and millimeter wave amplifiers and the need to know and understand their characteristics have led to the development of a pulsed noise analysis system. This system is capable of measuring amplitude, phase, and total spectra of two signals simultaneously. It can also measure am/pm conversion, group or phase delay and linearity, and phase and amplitude jitter. The system downconverts the signal to be analyzed and then digitizes the intermediate frequency. The digitized sample is transferred to a personal computer equipped with LabVIEW, where all further processing and analysis takes place. It is digitally demodulated into I and Q channels which can then be separated into amplitude and phase information. Discrete Fourier transforms are used display the spectral information. The system has achieved a dynamic range of 76 dB using a 10 bit 100 MS/s digitizer. Noise figure measurements as low as 21 dB above thermal have been performed. Additions to the system have begun to allow correlation and coherence studies. Measurements have been performed on both conventional linear beam devices such as commercially available TWT and klystron amplifiers. As well as two gyro-devices, the NRL gyroklystron and gyrotwystron amplifiers. These measurements were expanded to include noise power dependency on various tube parameters such as beam current and alpha. The results of the analysis will be used as a basis for modifying the gyrotwystron amplifier to improve its operating characteristics.