New Fiber Optic Analog Baseband Transmission Plan for Color TV Signals

A new fiber optic baseband analog transmission plan is proposed. It arranges the original signal into a pulse train for driving the laser diode to generate baseband components at the transmitter. The receiver can be just the same as those used in conventional direct linear intensity modulation systems using light emitting diodes (LED). Advantages of this new plan are (i) potentially cheap fibers can be used, since the plan requires neither an extra wide bandwidth nor special light acceptance conditions, (ii) long repeater spacings can be attained, since abundant light can be coupled into fibers using laser diodes and also the simple structures required for fibers are suitable for realizing low transmission losses, and (iii) the transmitter and receiver can be quite simple. Some candidate pulse arranging plans for generating baseband components are investigated. A pulse frequency arranging plan and pulse width arranging plan seem to be promising for efficient picture transmissions. An experiment using pulse frequency arrangement proves the theory developed here to attain a color TV transmission using a 10 km long step index low-loss fiber for a signal to noise ratio of 44 dB. Future improvements are expected by redesigning the transmitter and receiver and also by improving the mode stability of laser diodes.     

间歇采样转发干扰参数分析

间歇采样转发干扰的参数设置对干扰效果有较大影响,干扰参数决定了间歇采样转发干扰信号进入雷达接收机后的脉压结果。通过数学理论推导给出了间歇采样周期和干扰信号占空比两类干扰参数与干扰效果的明确数学对应关系,并通过数字仿真验证了数学推导和理论分析的正确性。     

Gigabit/s optical receiver sensitivity and zero-dispersion single-mode fiber transmission at 1.55 µm

High-speed pulse response and receiver sensitivity at 1.55 μm were measured at data rates ranging from 400 Mbits/s to 2 Gbits/s, in order to elucidate characteristics of a reach-through p+nn- Ge APD. The p+nn- Ge APD receiver provided a 2 Gbit/s received optical power level of -32.0 dBm at 1.55μm and a 10^-9error rate, which was 4 dB better than the receiving level with a p+n Ge APD. Detector performance at 1.3μm was also studied for comparison with performance at 1.55μm. Single-mode fibers, which have 0.54 dB/km loss and zero dispersion at 1.55μm, and an optical transmitter-receiver, whose repeater gain is 29.2 dB, have enabled 51.5 km fiber transmission at 2 Gbits/s. The transmission system used in this study has a data rate repeater-spacing product of 103 (Gbits/s) . km at 1.55μm. Optical pulse broadening and fiber dispersion were also studied, using 1.55 and 1.3μm dispersion-free fibers. Future repeater spacing prospects for PCM-IM single-mode fiber transmission systems are discussed based on these experimental results.     

A 132 Mb/s, 1bit 4224 M samples/s sub-sampling, low-complexity and energy-efficient BPSK transceiver for all-digital 3–5 GHz IR-UWB

In this paper, a 3–5 GHz impulse radio ultra wideband BPSK transceiver is presented. A new all-digital architecture is applied in the proposed transceiver. The transceiver has no mixer and low complexity. The transmitter employs a RLC network response filter to achieve the adjustable pulse parameters, which includes pulse width, pulse bandwidth and pulse amplitude. Considering the low duty ratio, a proposed on/off output buffer in the transmitter is applied to save the power consumption. To simplify the receiver, the radio frequency input signal is amplified and sampled directly by a 1bit 4224 MHz sub-sampling ADC. The ADC comprises by 16 paralleled comparators for low power. Each comparator operates at 264 MHz and can be self-calibrated. The transceiver is implemented in SMIC 0.13 μm CMOS process at the supply of 1.2 V. The measured results show the adjustable parameters: the pulse amplitude is from 110 to 370 mV, the pulse width is from 900 to 1,600 ns and the pulse bandwidth is from 2.0 to 2.78 GHz. The data rate is 132 Mb/s between the transceiver. The transmitter and the receiver only consume 18.2 and 330 pJ/pulse, respectively. The receiver sensitivity is ?75 dBm at the bit error rate of 10^?3.     

Gigabit/s Optical Receiver Sensitivity and Zero-Dispersion Single-Mode Fiber Transmission at 1.55 µm

High-speed pulse response and receiver sensitivity at 1.55 µm were measured at data rates ranging from 400 Mbits/s to 2 Gbits/s, in order to elucidate characteristics of a reach-through p/sup +/nn/sup -/ Ge APD. The p/sup +/nn/sup -/ Ge APD receiver provided a 2 Gbit/s received optical power level of -32.0 dBm at 1.55 µm and a 10/sup -9/ error rate, which was 4 dB better than the receiving level with a p/sup +/n Ge APD. Detector performance at 1.3 µm was also studied for comparison with performance at 1.55 um. Single-mode fibers, which have 0.54 dB/km loss and zero dispersion at 1.55 µm, and an optical transmitter-receiver, whose repeater gain is 29.2 dB, have enabled 51.5 km fiber transmission at 2 Gbits/s. The transmission system used in this study has a data rate repeater-spacing product of 103 (Gbits/s) /spl dot/ km at 1.55 µm. Optical pulse broadening and fiber dispersion were also studied, using 1.55 and 1.3 µm dispersion free fibers. Future repeater spacing prospects for PCM-IM single-mode fiber transmission systems are discussed based on these experimental results.     

Sensitivity enhancement of optical receivers by impulsive coding

A theory for the signal-to-noise ratio (SNR) of optical direct-detection receivers employing return-to-zero (RZ) coding (and possibly optical preamplification) is developed. The results are valid for both signal-independent noise limited and signal-dependent noise limited receivers, as well as for arbitrary optical pulse shapes and receiver filter characteristics. Even if the same receiver bandwidth is used, RZ coding is seen to perform better than nonreturn-to-zero (NRZ) coding. Asymptotic expressions for the SNR in case of very high and very low receiver bandwidths show that the full sensitivity enhancement potential of RZ coding is exhausted at fairly moderate duty cycles. A realistic example taking into account intersymbol interference (ISI) shows that a receiver sensitivity gain (compared to NRZ coding) of, e.g., 3.2 dB can be obtained in a signal-independent noise limited receiver with a bandwidth of 80% of the data rate, using a duty cycle of three     

Response of photovoltaic cells to pulsed laser illumination

Future space missions may use laser power beaming systems with a free electron laser (FEL) to transmit light to a photovoltaic array receiver. To investigate the efficiency of solar cells with pulsed laser light, several types of GaAs, Si, CuInSe₂, and GaSb cells were tested with the simulated pulse format of the induction and radio frequency (RF) FEL. The induction pulse format was simulated with an 800-watt average power copper vapor laser and the RF format with a frequency-doubled mode-locked Nd:YAG laser. Averaged current versus bias voltage measurements for each cell were taken at various optical power levels and the efficiency measured at the maximum power point. Experimental results show that the conversion efficiency for the cells tested is highly dependent on cell minority carrier lifetime, the width and frequency of the pulses, load impedance, and the average incident power. Three main effects were found to decrease the efficiency of solar cells exposed to simulated FEL illumination: cell series resistance, LC “ringing”, and output inductance. Improvements in efficiency were achieved by modifying the frequency response of the cell to match the spectral energy content of the laser pulse with external passive components     

High-accurate fault location technology using FSK-ASK probebackscattering reflectometry in optical amplifier submarine transmissionsystems

This paper proposes a new modulation format for optical time domain reflectometry (OTDR) to eliminate optical surge and improve OTDR performance in optical amplifier submarine transmission systems. The modulation format, FSK-ASK, uses a short high-power probe pulse and a long dummy pulse. Thanks to the slow gain dynamics of erbium-doped fiber amplifiers, both pulses experience an identical gain, equal to the loss of a span, so that the probe pulse maintains its high power and does not develop into an optical surge. Fault location experiments verify a theoretical prediction that FSK-ASK improves the signal-to-noise ratio (SNR) of OTDR by an amount as large as the power ratio of the probe to dummy signal. They also confirm the elimination of the optical surge caused by conventional OTDR using a solitary probe pulse. An FSK-ASK OTDR is applied in a commercial submarine amplifier transmission system which has a total transmission length of 890 km and a repeater spacing of 90 km. These field trial results show that subtle fiber anomalies can be located, with a spatial resolution of 1 km, along the entire length of the amplifier transmission system from a terminal end     

Optimum filter bandwidths for optically preamplified NRZ receivers

We present a comprehensive treatment of optically preamplified direct detection receivers for non-return-to-zero (NRZ) and return-to-zero (RZ) on/off keying modulation, taking into account the influence of different (N)RZ optical pulse shapes, specified at the receiver input, and filter transfer functions; optical Fabry-Perot filters (FPFs) and Bragg gratings as well as electrical fifth-order Bessel and first-order RC low-pass filters are considered. We determine optimum optical and electrical filter bandwidths and analyze the impact of bandwidth deviations on receiver sensitivity. Optimum receiver performance relies on a balance between noise and intersymbol interference (ISI) for NRZ transmission, while for RZ reception detection noise has to be traded against filter-induced signal energy rejection. Both for NRZ and 33% duty cycle RZ, optical filter bandwidths of around twice the data rate are found to be optimum. Receivers using RZ coding are shown to closely approach the quantum limit, and thus to outperform NRZ-based systems by several decibels. We further analyze the impact of important degrading effects on receiver sensitivity and optimum receiver bandwidths, including receiver noise, finite extinction ratio, chirp, and optical carrier frequency (or optical filter center frequency) fluctuations     

Fabrication and thermal performance of a novel TRAPATT diode structure

The development of TRAPATT diodes for long-pulse operation (10 to 100 µs), high duty cycle (1 to 15 percent), and wide bandwidth (12 percent), for phase array systems atFband requires new device fabrication and new heat-sinking technology. A novel TRAPATT diode in the form of interconnected long strips having high periphery-to-area ratio (cruciform) has been designed and fabricated. In this paper we described the thermal properties of the cruciform structure diode, which sustains 50-µs pulse width at 5.5-percent duty cycle while delivering 68-W RF power at 5-dB gain and 9-percent added efficiency, in addition to 100-µs pulse width at 4.2-percent duty cycle while delivering 50-W RF power output ast 3.6-dB and 5.5-percent added efficiency, both as narrow-band amplifier.     

Channel shortening equalizer for multi-access TH-UWB in the presence of multipath and multiuser interference

In this paper a novel channel shortening equalizer (CSE) for time hopping ultra wideband (TH-UWB) multiple access system with pulse position modulation (PPM) is presented. As UWB channels have very long impulse responses as compared to the narrow pulse width, CSE can reduce the number of correlators. In UWB systems, due to the received pulse that is very similar to the channel impulse response (CIR), the proposed algorithm maximizes the shortening signal to inter-symbol and multiuser interferences ratio (SSINR), defined as the ratio of the received signal energy inside the desired window to the energy in the wall and multiuser interference. The existence of the proposed CSE before correlation receiver decreases the complexity of the receiver architecture by significantly reducing the number of effective channel taps. Further we extend our method to derive general expression for the bit error rate (BER) performance in the presence of inter-symbol and multiuser interferences. Computer simulation results are provided to compare the performance of the proposed method with a MSSNR CSE, lower bound, also known as All-Rake, Partial-Rake, and Selective-Rake in terms of Rake operational temporal windows and BER.     

Theoretical and experimental analysis of the dependence of a signal's degree of polarization on the optical data spectrum

We show theoretically and experimentally the relationship between a signal's degree of polarization (DOP), all-order polarization mode dispersion (PMD), and the optical spectrum (and hence the data modulation format and pulse width), and that these effects must be taken into account when using the DOP for differential group delay (DGD) monitoring. We explain the theory behind how all-order PMD affects a signal's DOP, and observe the pulse-width dependence for 10-, 20-, and 40-Gb/s return-to-zero (RZ) systems as the duty cycle changes. We then analyze and show (via simulation and experimentation) the effects of different data modulation formats (RZ, carrier-suppressed RZ, alternate-chirped RZ, and differential phase-shift keying) on the DOP in a DGD monitor. We conclude that the measurable DGD range and DOP sensitivity in DOP-based DGD monitors are dependent on a signal's pulse width and the data modulation format. We also show the theory behind the effects of first- and second-order PMD on the maximum and minimum DOP.     

高灵敏度星载ADS-B信号解调算法

为提高星载自动相关广播监视系统(ADS-B)接收机的检测性能,研究了高灵敏度解调算法。利用基于匹配滤波的ADS-B信号帧头检测算法对信号准确定时和提取功率信息,该方法构建了特殊的帧头匹配脉冲序列,设计了信号控制状态机以确保在相关峰值最大处定位信号,并联合一部分数据位进行同步。利用多点加权振幅采样法提取比特信息和置信度。最后,采用基于置信度的纠错方法纠正校验错误的报文。板载验证表明,该解调算法能有效提升低信噪比条件下星载ADS-B信号的检测概率,最终接收机的灵敏度可达-95 dBm(数据包错误率5%)。     

Optical Pulse Formats for Fiber Optic Digital Communications

Some new optical pulse formats are investigated for solving practical problems in fiber optic communication systems. These pulse formats provide many advantageous features such as error monitoring capability, abundant timing information, uniform optical power utilization, stable detection of optical input, and so forth. It is shown that a modification of Personick's receiver design theory can be used for comparison of various optical pulse formats. The comparison suggests that for state-of-the-art fiber systems with moderate fiber loss and moderate repeater spacing, where no pulse equalization is required, some new classes of 1 binary digit converted to 2 binary digits (1B2B) or 2B3B formats will permit the realization of very simple and reliable repeaters for fiber optic digital transmission. A future low-loss fiber system may permit a very long repeater spacing with the help of equalization. In this case, application of the correlative signal-processing technique is shown to be very promising. Experimental 6.3 Mbit/s and 100 Mbit/s transmissions demonstrate some advantageous features of these optical pulse formats.     

Low-noise optical detection of a 1.1 Gb/s optical data stream

A low-noise, 1.1 Gb/s optical receiver has been built using a silicon a.p.d. and a GaAs f.e.t. The receiver sensitivity was evaluated using error-rate measurements, and for a bit error rate of 10?9, with no fibre, the measured optical sensitivity was ?37.0 dBm. These results are used as a basis for the calculation of maximum repeater spacings for 1.1 Gb/s systems operating at 0.85 ?m and 1.25 ?m wavelengths.     

实施转发式GNSS欺骗干扰的功率控制策略研究

在实施转发式欺骗干扰时,经转发的干扰信号和直达信号同时进入被干扰接收机,对接收机的信号处理过程造成复杂的影响.转发式干扰根据信号功率的大小,其干扰效果可能会出现信号压制、信号欺骗或无法欺骗等多种情况,目前尚无文献对转发干扰信号功率控制进行定量研究.为推进转发式欺骗干扰在导航战中的实际应用,制定合适的转发式欺骗干扰功率控...     

A Design of BASK System for Giga-bit Modem

We propose a binary amplitude shift keying (BASK) system of Giga-bit Modem without intermediate frequency process for the 60 GHz band. The proposed system consists of a high speed shutter of the transmitter and a repeater of the receiver. The shutter of the proposed system is introduced for pulse shaping to improve the intersymbol interference (ISI). The repeater consists of several stage converters. A converter is constructed with a low pass filter and a limiter. The repeater can improve the signal-to-noise ratio (SNR) and make the rectangular pulse train. The advantage of the proposed system is very simple without the intermediate frequency (IF) process. Ki-Hwan Eom was born in Seoul, Korea in 1949. He received the B.S. degree from Dongguk University, the M.S. degree from Inha University, and Ph.D. degree in electronic engineering from Dongguk University, Korea in 1972, 1975 and 1986, respectively. He was a visiting professor from 1989 to 1990 at Toho University, and from 2000 to 2001 at University of Canterbery. Since 1994, he has been with Dongguk University, where he is currently a Professor in the Department of Electronic Engineering. Seong-Ho Kang was born on September 5, 1972. He received the B.E. from JinJu National University in 2000 and Ph.D. degree from Dongguk University in 2006. His research interests are in communication systems and intelligent systems. Yoichi Sato was born on October 2, 1939. He received the B.E. from Kyoto University in 1963 and Ph.D. degree from Waseda University in 1976. From 1963 to 1982 he was a Research Engineer in the Central Research Labs. Of NEC Corporation. He joined Toho University in 1982. He is a Professor emeritus of the Department of Information Sciences in Toho University. He is a member of the IEEE Communication Society.     

GaAs m.e.s.f.e.t. technology and characteristics for optical communication systems

For pulse regeneration applications GaAs m.e.s.f.e.t.s with low pinch-off voltages are desirable. The technology and the dependence of the input/output pulse width ratio on the bias voltage are described. The pulse behaviour of a two-stage sharpener is shown and the block diagram of an optical repeater station is proposed.     

一种ADS-B报头互相关检测方法

广播式自动相关监视( ADS-B )报头检测方法的优劣直接决定着接收机的性能。为了解决脉冲匹配检测方法受脉冲能量影响较大的不足,提出了一种基带归一化的互相关报头检测方法。首先将基带信号根据动态门限进行归一化,然后将其与标准报头作互相关,最后通过相关峰检测来判定信号的存在和到达时间。与主流基于脉冲位置和上升沿的检测方法相比,该方法隐含地利用了脉冲位置、上升沿、下降沿、脉冲宽度、非脉冲区等多个信息用于检测报头,且无需进行下行格式( DF )认证。仿真结果表明：该方法在信噪比大于2 dB时检测性能略优,在信噪比小于2 dB时检测性能与主流检测方法相差1 dB。在实际接收实验中,以该方法为基础的信号接收效果良好,在视距内可以形成稳定连续的航迹,证明了该方法的实用性。     

间歇采样非均匀重复转发实现多假目标压制干扰

针对采用均值类恒虚警检测方式的线性调频脉冲压缩雷达,本文提出间歇采样非均匀重复转发(ISNPR)实现多假目标压制干扰的方法.首先阐述了间歇采样转发干扰(ISRJ)产生多假目标的机理,同时对多假目标压制干扰的假目标参数进行了推导,包括假目标个数和信噪比.然后结合间歇采样重复转发干扰(ISPRJ)的数学原理,对间歇采样非均匀重复转发干扰(ISNPRJ)的多假目标压制效果进行了理论分析,并推导了干扰机参数如采样脉冲宽度、间歇采样周期、转发脉冲宽度以及发射功率的计算方法.最后对ISNPRJ的多假目标压制效果进行仿真验证,仿真结果表明该方法能够降低雷达对目标的检测概率,实现对雷达检测环节的有效压制.