CMOS LED-driver and PIN-receiver for fiber optical communication at 155 Mbit/s

A test chip for an integrated full cmos led driver has been realized with a modulation current of 60 mA at a maximum bit rate of 155 Mbit/s. A cmos receiver is evaluated to amplify pin diode photo currents less than 10 μA at the same bit rate of 155 Mbit/s. Both circuits are integrated on one chip. The circuit has been developed in a 0.8 μm digital cmos process.     

1 Gbit/s high-speed bit-synchronisation LSI for B-ISDN

The CCITT recommended that the bit rates for synchronous digital hierarchy (SDH) should be multiples of 155.52 Mbit/s. In handling high-speed data (such as 622.08 Mbit/s) in B-ISDN switching systems, there are problems associated with waveform degradation caused by impedance mismatching and amplitude attenuation. A countermeasure is the regeneration of the distorted waveforms using the system clock in each board. A bit-synchronisation circuit allows distorted waveforms to be regenerated and simplifies the design of timing between boards. The author have developed a high-speed bit-synchronisation LSI with excellent jitter tolerance in the 600 Mbit/s region and which has a simple circuit structure. The LSI features a circuit structure based on an elastic store, Si-bipolar super self-aligned process technology (SST),/sup 1/ and careful timing design. It can handle three different bit-rates (622.08, 155.52, and 51.84 Mbit/s) and has a maximum bit rate of 1 Gbit/s.<>     

1 Gbit/s transmission experiment over 101 km of single-mode fibre using a 1.55 ?m ridge guide C3 laser

Using a cleaved-coupled-cavity (C3) ridge guide laser which oscillates in a single longitudinal mode at 1.55 ?m wavelength, we report the first lightwave transmission experiment exploying single-frequency lasers at speeds above 500 Mbit/s. We have achieved digital transmission with a bit-error rate of 2 × 10?10 at 1.0 Gbit/s over 101 km of single-mode fibre. This represents a record for the length of unrepeatered optical transmission for bit rates greater than 500 Mbit/s. Evidence for an error-rate floor, presumably due to residual partition noise, is observed. No such floor was observed in an 84 km?1 Gbit/s experiment using the same C3 laser.     

Investigations on bit error performance for video over DAB

The digital audio broadcasting (DAB) system which was originally designed for high quality audio transmission to mobile receivers is investigated for transmission of compressed digital video and multimedia signals. The bit error performance is considered using various levels of error protection provided by the DAB system. As a result, a net bit rate of about 1.5 Mbit/s can be achieved. With additional error correction coding, a bit error ratio (BER) of less than 10^-10 can be realized. This is the requirement for compressed video signals. The SNR per bit is below 16 dB. The results are demonstrated and compared using computer simulations of the complete system     

Transmission of 622 Mbit/s spectrum-sliced WDM channel over 60 kmof nondispersion-shifted fibre at 1550 nm

The transmission of a spectrum-sliced WDM channel at 622 Mbit/s over 60 km of nondispersion-shifted fibre using an optical bandwidth of only 0.23 nm is reported. This is the highest single channel bit rate-length product (40 Gbit/s·km) and smallest channel bandwidth reported to date for spectrum-sliced WDM systems. The bit error rate performance is theoretically predicted and experimentally confirmed and limits on the bit rate-length products of spectrum-sliced WDM channels using nondispersion-shifted fibre in the 1550 nm window are given     

Effect of semiconductor laser phase noise on BER performance in an optical DPSK heterodyne-type experiment

We report the first experimental investigation of the effect of laser-diode phase noise on the error-rate performance in a PSK heterodyne differential detection fibre communication experiment. A newly designed AlGaAs laser emitter with adjustable linewidth is used as both the signal carrier and the local oscillator. Error rate is measured for 25 Mbit/s and 50 Mbit/s signals at an intermediate frequency of 250 MHz, and a BER (bit error rate) of 10?10 has been achieved.     

Simplified 6.3 Mbit/s Codec for Video Conferencing

A color TV codec with a 6.3 Mbit/s transmission bit-rate has been simplified by a newly developed coding method. This method is the combination of a 4-to-1 dot interlace system and 4 bit/pel DPCM. A digital filtering technique for reducing coding distortion is also employed. In comparison with an interframe codec having the same transmission bit-rate, the amount of codec circuitry is halved. Subjective tests were performed to investigate the coded picture quality. It was found that this codec can present acceptable pictures for video conferencing, and that the picture quality for rapidly moving subjects is the same as that of the interframe codec operating at the same bit-rate. A video conferencing system via a digital satellite link has been constructed for experiments by employing this codec. The experiments showed that the satellite link has a sufficiently low transmission error rate for the coded pieture transmission. Moreover, it has been proved that transmission delay does not pose any problems for normal conferences.     

Linewidth requirement evaluation and 290 km transmission experiment for optical CPFSK differential detection

The linewidth requirement for CPFSK differential detection is evaluated. CPFSK modulation of DFB-LD is confirmed from the spectrum correlation between an output spectrum and calculated results. In a 1.55 ?m 400 Mbit/s transmission experiment using a 290 km pure-silica-core fibre, average received optical power at a 10?9 bit error rate is ?49.9 dBm.     

A 105 Mbit/s Error Correcting Codec

A 105 Mbit/s experimental error correcting encoder/ decoder is described. The device exhibits a coding gain of 1.9 dB at a 10^-5bit error rate and has a 25 percent parity bit overhead. The decoder was constructed without syndrome reset. This allowed the operating speed to be more than doubled, while only sustaining a negligible loss in performance.     

32 Mbit/s Transmission of NTSC Color TV Signals by Composite DPCM Coding

A composite DPCM coding System was developed, which is capable of coding and transmitting an NTSC color TV signal without component separation at a 32.064 Mbit/s rate. The DPCM prediction method used is based on the algorithm that a luminance component prediction valuehat{y}and a carrier chrominance component prediction valuehat{c}are calculated individually, and then the composite signal prediction valuehat{x}is determined byhat{x} = hat{y} + hat{c}. In order to utilize horizontal blanking (HBL) intervals for transmitting active video signals,HBL signals are not transmitted in each line but their representative signals are transmitted once a frame during a vertical blanking interval. A dual word-length coding and quantizing method is adopted, which uses 4 bit and 8 bit words with average word-lengths of 4.4 bits/sample. Codec equipment was fabricated, and coding and transmitting experiments were conducted, using NTT's PCM-100 M digital repeatered line. Experimental results show that this composite DPCM coding system can be employed for digital transmission of NTSC color TV signals, such as color ITV signals, at a 32.064 Mbit/s rate.     

Dégradation de la qualité due aux trajets multiples dans un système a transmission numérique a quatre états de phase

A study is made on the effect of propagation on digital transmission based on two series of measurements made with four phase shift keying and differential demodulation equipment at bit rates of 38.8 and 216 Mbit/s. Degradation due to selectivities of attenuation caused by multipath propagation is inferred for both experiments : whereas the degradation is low at 38.8 Mbit/s, it becomes very large at 216 Mbit/s. The results are interpreted and commented upon. By taking a dual beam model, a calculation is made for degradation due to propagation under multipath conditions, as a function of the delay of the reflected beam.     

Coherent optical receiver for 680 Mbit/s using phase diversity

A coherent optical receiver using a multiport optical coupler to provide phase diversity is described. By this means, only homodyne bandwidth is required in the signal processing, but with tolerances on the frequency tracking typical of heterodyne systems. Measured sensitivities with limited local-oscillator power are ?47.5 dBm at 320 Mbit/s and ?42 dBm at 680 Mbit/s. The results at the higher bit rate are strongly influenced by limited receiver module bandwidth.     

Simple common-collector full-monolithic preamplifier for 560 Mbit/s optical transmission

A simple common-collector full-monolithic preamplifier is developed using an advanced 3 ?m Si-bipolar IC technology SICOS. The amplifier characteristics are a 650 MHz bandwidth and a 5.2 pA/?(Hz) equivalent input noise current at a 3 k? transimpedance. Measured optical sensitivity of a front end consisting of the amplifier and a Ge-APD is ?36.2 dBm for an error rate of 10?9 at a 560 Mbit/s bit rate and 1.3 ?m wavelength.     

256 QAM Modem for Multicarrier 400 Mbit/s Digital Radio

This paper describes the performance of a 256 QAM modem with 400 Mbit / s transmission capacity. A variety of novel techniques are introduced as ways to achieve good performance. Key techniques include 1) an accurate 256 QAM modulator employing a new monolithic multiplier IC, 2) a carrier recovery circuit which satisfies such requirements: good phase jitter performance and no false lock phenomenon, 3) a highly stable high-level decision circuit, and 4) a forward error correcting code. As an overall modem performance, BER characteristics and signatures are presented. The equivalent CNR degradations of 1 dB(at BER of 10^-4) and 2 dB (at BER of 10^-9)are obtained using a single Lee-error correcting code and a seven-tap baseband transversal equalizer. The residual bit errors are decreased below the order of 10^-10. The performance of a 256 QAM multicarrier modem has given prospect for the development of 400 Mbit/s digital microwave radio system.     

640 Mbit/s waveguide transmitter at 38 GHz

The principle of a digital waveguide transmitter working at 38 GHz is given. A pulse-code-modulation simulator, with a bit rate of 640 Mbit/s, produces the modulation signal and also allows error-rate measurements. Typical switching times of the modulator are less than 500 ps. These results have been obtained by use of a varactor diode installed in a rectangular R band waveguide.     

同步数字体系中155Mbit/s净荷的误码测试

本文基于光纤传输同步数字体系(S D H)系统的开发背景,较为详细地总结了155Mbit/s速率下的净荷误码测试机理.最后给出了净荷的误码测试方法以及误码测试系统的信号流程.     

8 GHz, 10 W solid-state power amplifier for microwave digital radio

An 8 GHz, 10 W GaAs FET prototype power amplifier has been developed to replace the TWT in the Northern Telecom's digital microwave radio system. For a single bit stream of 91.04 Mbit/s, the residual bit error rate at 40 dBm output level was 1.0×10?32 compared with 1.0×10?23 for TWT; the AM/AM conversion ratio was 0.375 dB/dB and AM/PM was 0.84°/dB. The total mean time between failure of the amplifier was 350 000 h.     

`Nearly instantaneous? digital compandor for transmitting six sound-programme signals in a 2.048 Mbit/s multiplex

A `near-instantaneous? digital compandor for the transmission of high-quality sound signals is described that reduces the bit rate from 416 kbit/s to about 322 kbit/s per channel without noticeable impairment of the sound quality. Hence six audio channels can be multiplexed to form a 2.048 Mbit/s stream including frame synchronisation and transmission error-protection facilities.