Objective and subjective impairments in a displayed colour picture can be evaluated accurately by analysing the component colour video signals. Objective noise performance of component colour video signals in a TV monitor is investigated. This analysis takes in to account the effect of nonlinearity of the display tube. The impairment in the displayed picture is a function of the magnitude and spectra of the input noise. Two commonly occurring noise spectra are considered. They are triangular (deemphasised), and white noise. >
A refractometer for liquids, based on optical frequency-domain reflectometry, is described which uses a simple fibre probe with minimal contact area with the test liquid. The sensitivity is much better than in earlier reported fibre refractometers.
An analogue optical link for multichannel video is described, using a 1.3 μm multimode laser diode and single-mode fibre. High-quality transmission is achieved by optimising the frequency deviation and interchannel spacing, in the FM/FDM format employed.
The theoretical aspects of colorimetric noise analysis of an optical fiber receiving system for multichannel television signals is investigated. The effect of display tube nonlinearity on the optical front-end receiver noise is discussed, and an expression for display signal-to-noise ratio (DSNR) is derived. A relation between the standard International Radio Consultative Committee (CCIR) SNR and the DSNR is established. This is used to analyze the displayed picture quality quantitatively in terms of various hues of different saturations. The way in which the displayed picture quality can change under different luminances, is shown.< >
The performance of an analogue optical fibre system for transmitting five video channels is investigated. A 1.3μm single longitudinal mode laser diode and a pinFET receiver are employed. Source and detector noise are both considered.
The objective signal-to-noise performance of component colour video signals is analysed in this paper for FM and AM-VSB video transmission systems. In the analysis, the effect of splitting the composite video signal into its components, by subcarrier demodulation and colour decoding, is taken into consideration. The effect of non linearity of the display is also included in the analysis. An expression for objective component signal-to-noise ratio is derived for both the transmission systems. A relationship between the conventional composite video SNR and the component video SNR is established. Effective noise transfer, between the input and various stages of video signal processing, is discussed in detail. Noise spectral density analysis, for fully saturated primary colours, is evaluated quantitatively for a PAL-I video system. Finally, SNR performance of various hues at constant luminance is evaluated, and the results obtained are compared with the subjective noise visibility tests first carried out in 1957.
An 835 nm superluminescent diode with a spectral width of 8 nm is shown to reduce SNR fluctuations due to modal noise significantly in PFM optical video transmission. An SNR of 56 dB and DG/DP of 06%/0.3° are achieved over 5 km with a frequency deviation of only 400 kHz. The SNR fluctuation is less than 0.05 dB.
Optical fibre sensors are attractive for sensing applications in hazardous and in hostile environments. An investigation into a frequency domain, multiplexed optical fibre sensor for in-process and simultaneous measurement of multiple properties of liquids is reported.
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