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The paper is devoted to the theoretical and experimental investigation of spatial resolution of images obtained during acousto-optic spectral filtration. The consideration was carried out for a wide angle acousto-optic filter designed on the base of paratellurite single crystal. The crystal was cut in the (i To) plane with the direction of acoustic wave propagation at the angle 100 relative to the axis [1 10]. It was found that optical quality of a filtered image is influenced by a spectral bandwidth of a filter. The spectral bandwidth is determined by a length of a piezoelectric transducer that generates ultrasonic waves in an acousto-optic cell. The dependence of a number of resolvable spots on the piezotransducer length was examined theoreticaly. It was shown that a wavelength of the filtered radiation influences the quality of the prosessed image. Precise and approximate equations have been derived to determine the spectral passband of the acousto-optic filter, the angular field of view of a single pixel, the angular aperture of the device and the number of resolvable spots in a line. Resolution of the images obtained during the acousto-optic filtration was also measured in the experiment.

Many modern telecommunication systems rely on a common signal source to serve as a phase and frequency reference signal for the network. This source is often employed to synthesize microwave transmit and receive signals locally for gateway signal processing purposes and to serve as a reference for the remotely located signal sources in the network. This scheme has the advantage of providing end-to-end network synchronization and reducing the cost of the remote terminals by requiring a high-performance phase and frequency source only at the gateway site.Achieving extremely low-phase noise for this common reference source in order to meet the performance demands over microwave radio links is the challenge. The high phase noise multiplication factor associated with this process drives the phase noise performance of the reference source to be state of the art.Electronic equipment for gateway telecommunications facilities is typically fashioned using a modular chassis-in-rack concept. This concept provides ease of maintainability and design configurability through an industry-standardized rack and chassis mounting system. In some applications, the racks are located on elevated flooring in order to facilitate inter-rack connectivity and site thermal management. This physical approach to gateway site facilities, while succeeding in providing a useful realization of the aforementioned design needs, does not provide a vibration-free environment for sensitive phase and frequency signal sources. The source of the vibration energy, due to mechanical influences, is notably from site air movement equipment, localized rack cooling blowers, staff operations (walking, closing of doors, etc.), physical building movement, etc.A design solution for this gateway application that employs a g compensated quartz crystal oscillator as a signal source is presented. This signal source is mounted on a vibration isolation device to effectively remove the residual mechanical vibration disturbances affecting phase noise. The oscillator utilizes a Stress Compensated (SC) cut quartz resonator with optimized circuit design and g compensation functionality to achieve state-of-the-art phase noise performance. The vibration isolation device features an entirely passive implementation and excellent mechanical isolation capabilities at a reasonable cost. The resultant phase noise performance under operational vibration conditions is nearly equivalent to the quiescent, at-rest, performance. The composite g sensitivity is better than 1 X 10 -11 /g at 5 Hz offset for this system application.

S(t) =AO(I + 40 J sin(2lrfo t + t)I, (1) The accuracy increasing for digital algorithms of noise phase modulation calculations is urgent as for some measurements and especially for processing of signals which have been obtained by means of Computer Aided Design software. Calculation accuracy limits an application of digital algorithms for precision oscillations research.

This paper discusses how an non-linearity of oscillating stage affects phase noise performance of a UHF band Voltage Controlled Crystal Oscillator (VCXO). The developed oscillator is based on Colpitts circuit and on quartz crystal resonator with 100-160 MHz frequency of fundamental mode. The non-linearity is an unavoidable part of any oscillator. So, in order to obtain UHF band signal, we have chosen a method of already existing harmonic selection (in that oscillating stage). This approach allows to achieve phase jitter not exceeding 1.0 ps RMS for output signal in UHF band. Phase noise spectral density and signal spectral purity have taken in to consideration as the main parameters of the oscillator quality. The main question of researches was how the increase of a power level of one harmonic will affect a level of the phase noise. The obtained experimental results show that in certain conditions fundamental oscillation and desired harmonic at any rate do not counter interact each other then low phase jitter is achieved.

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