Bstj 45: 7. September 1966: Signal-to-Noise and Idle Channel Performance of Differential pulse code Modulation Systems - Particular Applications to Voice Signals. (McDonald, R.A.) by published by
Bstj 45: 7. September 1966: Signal-to-Noise and Idle Channel Performance of Differential pulse code Modulation Systems - Particular Applications to Voice Signals. (McDonald, R.A.) by published by
Shapiro steps crossing the zero-current axis, i.e., zero-crossing steps, in the overdamped Josephson junction driven with a simple pulse code consisting of single and multiple pulses in each repetition period are stud...
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Shapiro steps crossing the zero-current axis, i.e., zero-crossing steps, in the overdamped Josephson junction driven with a simple pulse code consisting of single and multiple pulses in each repetition period are studied based on numerical simulations. In this study, it is confirmed that the quantized. voltage at which the zero-crossing step appears can be controlled by the number of the additional pulses without changing current bias range. The case in which the additional pulses having small fluctuations in phase is also considered. No visible effect of the fluctuations on the current position of the Shapiro steps is observed, so that the current range with respect to the phase lock between the Josephson oscillation and the pulse code is determined by the number of pulses.
Laser pulse code is an anti-jamming measures used in semi-active laser guided weapons. On account of the laser-guided signals adopting pulse coding mode and the weak signal processing, it need complex calculations in ...
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ISBN:
(纸本)9780819488336
Laser pulse code is an anti-jamming measures used in semi-active laser guided weapons. On account of the laser-guided signals adopting pulse coding mode and the weak signal processing, it need complex calculations in the frequency measurement process according to the laser pulse code signal time correlation to meet the request in optoelectronic countermeasures in semi-active laser guided weapons. To ensure accurately completing frequency measurement in a short time, it needed to carry out self-related process with the pulse arrival time series composed of pulse arrival time, calculate the signal repetition period, and then identify the letter type to achieve signal decoding from determining the time value, number and rank number in a signal cycle by Using CPLD and DSP for signal processing chip, designing a laser-guided signal frequency measurement in the pulse frequency measurement device, improving the signal processing capability through the appropriate software algorithms. In this article, we introduced the principle of frequency measurement of the device, described the hardware components of the device, the system works and software, analyzed the impact of some system factors on the accuracy of the measurement. The experimental results indicated that this system improve the accuracy of the measurement under the premise of volume, real-time, anti-interference, low power of the laser pulse frequency measuring device. The practicality of the design, reliability has been demonstrated from the experimental point of view.
In this paper the design and analysis of an experiment are presented, which was conducted in order to assess the subjective impact of transmission delay on mobile voice communications via satellite, This study was con...
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In this paper the design and analysis of an experiment are presented, which was conducted in order to assess the subjective impact of transmission delay on mobile voice communications via satellite, This study was conducted using simulated end-to-end propagation delays representative of low earth orbit (LEG) and geostationary earth orbit (GEO) networks (single and double-hop) in combination with three different speech coding technologies: 64 kb/s pulse code modulation, 8 kb/s vector-sum excited linear prediction, and 4.15 kb/s improved multiband excitation (representing wireline, cellular, and mobile-satellite technologies, respectively), Subsequent analysis included computation of the cross-correlation between delay and coding method, from which it was concluded that for ''wireline-quality'' and ''communications-quality'' circuits transmission performance somewhat degraded as propagation delay increased to that of a double-hop GEO circuit, However, for ''communications quality'' circuits employing the 4.15 kb/s speech coding algorithm, transmission performance remained constant as propagation delay increased.
A three-state signal coding scheme is proposed for driving Class-S amplifiers with higher efficiency than conventional techniques. The approach is formulated in the framework of polar modulation, where the magnitude i...
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A three-state signal coding scheme is proposed for driving Class-S amplifiers with higher efficiency than conventional techniques. The approach is formulated in the framework of polar modulation, where the magnitude is controlled by a timing code that specifies positive and negative rectangular pulses as well as a third zero state, and the phase is varied by modulating the clock delay. In particular, high efficiency is attained when the active pulse widths are a half-cycle of the carrier frequency, and the zero-state is formed by skipping pulses. In this case, full-amplitude modulation has the same efficiency as a Class-D amplifier, and is only slightly degraded as the amplitude is decreased. In addition, the technique operates at only sampling and is very simple to implement. Spectral analysis is performed for baseband signals consisting of single tones, 2-tone suppressed-carrier, and bandlimited random noise. The latter case emulates real communication signals and is shown to exhibit good spectral characteristics and low error-vector magnitude in the time domain. An important application of this technique is in all-digital, power-efficient power amplifiers for cellular base stations and handsets.
A three-state signal coding scheme was recently proposed by the author for driving Class-S amplifiers with higher efficiency than conventional techniques. The magnitude is controlled by a timing code that specifies po...
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A three-state signal coding scheme was recently proposed by the author for driving Class-S amplifiers with higher efficiency than conventional techniques. The magnitude is controlled by a timing code that specifies positive and negative rectangular pulses as well as a third zero state. High efficiency is attained when the active pulse widths are a half-cycle of the carrier frequency, and the zero state is formed by skipping pulses. Good spectral characteristics and low error-vector magnitude are achieved for fixed carrier frequency, where output filtering can be effectively employed. However, for applications requiring operation with signals spectrally located anywhere within a much wider service bandwidth, intermodulation effects limit the adjacent channel leakage ratio (ACLR). In this brief, we explain this fundamental limitation and propose combining three-state coding with pulsewidth modulation (PWM) as a remedy. The combined three-state/PWM scheme enables a tradeoff to reduce ACLR while not seriously compromising efficiency.
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