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Modulation Index and FM Improvement for Analog TVBaylor, J. Thomas 11 1900 (has links)
International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The concepts of modulation index and FM improvement are simple and straightforward when the modulating signals are sinesoidal. For a complex baseband waveform such as analog TV, the FM improvement may be seriously underestimated.
A method for computer simulation of video waveforms and the resulting spectra are presented.
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Optimum Subcarrier Deviation for PCM/FM+FM/FM Systems using IRIG Constant Bandwidth ChannelsOsborne, William P., Whiteman, Donald E. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A typical PCM/FM system is designed for a peak to peak carrier deviation of 0.7
times the bit rate of the PCM data. This value of PCM data deviation has been shown
to be optimum for both PCM/FM [1] and PCM/FM+FM/FM [2] systems. However,
the optimum deviation of the carrier by the FM subcarrier for a PCM/FM+FM/FM
system is dependent upon the specific subcarrier type and required subcarrier signal to
noise ratio at the receiver output.
This paper introduces a simple method to calculate the optimum deviation of the
carrier by FM subcarriers for a PCM/FM+FM/FM system. The method developed is
used to calculate the optimum value of subcarrier deviation for two sample
PCM/FM+FM/FM systems when IRIG constant bandwidth channels are used as FM
subcarriers. The calculated optimum values of FM subcarrier deviation of the carrier,
subcarrier mod index, are utilized in a companion paper to study the performance of
PCM/FM+FM/FM systems [3].
The work presented herein can be extended to calculate the optimum deviation of the
carrier by FM subcarriers for any PCM/FM+FM/FM system.
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Dynamic Linkage Between Local Cross-frequency Coupling and Communication Through Coherence in an in Vitro Model of Human Neocortical Oscillatory ActivityMcGinn, Ryan J. 05 December 2013 (has links)
The dynamical underpinnings of complex computation and information transmission within the brain, while of great interest to the neuroscience community at large, remain poorly understood. One of the striking manifestations of neuronal population activity is that of rhythmic oscillations in the local field potential. It is thought that distinct patterns of these oscillations such as cross-frequency coupling within a given spatial location and coherence between disparate brain regions may represent neuronal computation and communication, respectively. Here we show such dynamics within a human temporal neocortical in vitro model. In specific, we show theta-gamma cross frequency coupling in deep and superficial layers, phase coherence between layers at theta frequencies, and a measure of communication (phase dependent power correlations) between layers at theta frequency. Additionally, we show a novel correlation between communication across layers and cross frequency coupling within layers, demonstrating a dynamic link between local computation and intralaminar communication.
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Dynamic Linkage Between Local Cross-frequency Coupling and Communication Through Coherence in an in Vitro Model of Human Neocortical Oscillatory ActivityMcGinn, Ryan J. 05 December 2013 (has links)
The dynamical underpinnings of complex computation and information transmission within the brain, while of great interest to the neuroscience community at large, remain poorly understood. One of the striking manifestations of neuronal population activity is that of rhythmic oscillations in the local field potential. It is thought that distinct patterns of these oscillations such as cross-frequency coupling within a given spatial location and coherence between disparate brain regions may represent neuronal computation and communication, respectively. Here we show such dynamics within a human temporal neocortical in vitro model. In specific, we show theta-gamma cross frequency coupling in deep and superficial layers, phase coherence between layers at theta frequencies, and a measure of communication (phase dependent power correlations) between layers at theta frequency. Additionally, we show a novel correlation between communication across layers and cross frequency coupling within layers, demonstrating a dynamic link between local computation and intralaminar communication.
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