摘要:

Series-parallel signal generation and processing techniques are identified which may be used to circumvent the speed limitations of available logic devices in realising bit error ratio measurements for high-digit-rate transmission systems. New techniques are proposed which offer advantages in enabling devices to be used near their maximum operating rate while achieving, by virtue of the parallelism inherent in the structures proposed, yet higher data throughout rates. The specific application of these techniques to highspeed line-coded test signal generation and error detection is examined, and the series-parallel generators are shown to be particularly well suited to the economical realisation ofmB(m+1)B block-coded test signals.

DOI:10.1049/ip-f-1.1987.0076

出版商:IEE    

年代:1987

数据来源: IET

摘要:

A Gaussian regression algorithm is proposed for reducing bit error rate (BER) measurement time and facilitating, by extrapolation, a bit error probability estimation as a function of the signal/noise ratio. The application of this algorithm is illustrated in two BER measurement methods using noise injection or decision threshold level shifting. The overall performance assessment of a system (error probability as a function of the signal/noise ratio and noise standard deviation in the absence and in the presence of the signal) are thus obtained.

DOI:10.1049/ip-f-1.1987.0077

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The probability of incorrect reception of a transmitted bit under hostile propagation conditions is commonly estimated from bit error ratio measurements performed in the presence of additive white noise and interference. The paper stresses the effects of the finite crest factor of realisable noise sources on the theoretical error probability of digital radio systems. Formulas are presented for calculating this under given combinations of noise, interference and crest factor for common modulation schemes, and are suitable for simple numerical integration on desk-top calculators. Some implications for test equipment design are highlighted. The residual error rate of digital radio systems is so low that it is not practical to measure it directly. However, an estimate can be made by adding sinusoidal interference to produce the carrier/interference ratio (CIR) required to establish a specific error rate, dependent on the amount of residual noise present around the phase states in the constellation employed.

DOI:10.1049/ip-f-1.1987.0078

出版商:IEE    

年代:1987

数据来源: IET

摘要:

For constructing reliable, high-grade digital transmission networks, exact failure or degradation detection in digital transmission equipment, such as regenerative repeaters, is important. A new measurement for eye opening estimation of equalised signals, called the transmission waveform deflection-type margin (TWDM) measuring method, is proposed. The principles of the method are described and the measurement accuracy in relation to measurement time required is analysed. Experimental results are presented and the measurement method shown to have a wide range of applications.

DOI:10.1049/ip-f-1.1987.0079

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Different statistical distributions of errors (isolated and in bursts) were provoked on digital systems. Binary errors and errors estimated by ‘coding rule violations’ were compared for the HDB3 and 4B3T codes. In the case of the HDB3 code, 85% of isolated binary errors are detected. However, only 15% of burst errors are detected. In the case of 4B3T with an asynchronous scrambler, it may be considered that one code error corresponds to 10 binary errors, on average. Results with burst errors are quite different from theoretical evaluation for isolated errors. These results must be considered when evaluating ‘degraded minutes’ and ‘severely errored seconds’ of CCITT Recommendation G.821 for operating digital systems.

DOI:10.1049/ip-f-1.1987.0080

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The topics of jitter origin, accumulation and control are vitally important in digital systems and networks, and form an important part of the relevant performance specifications. The principal properties of jitter are summarised and the philosophy behind current international specifications explained. A review of measurement requirements and techniques for testing the jitter performance of digital transmission equipment is given, and the paper concludes with a brief consideration of jitter assessment in systems and networks of the future.

DOI:10.1049/ip-f-1.1987.0081

出版商:IEE    

年代:1987

数据来源: IET

摘要:

An assessment of subscriber loop copper pairs for digitised data transmission includes capturing the effects of noise such as crosstalk, background noise and impulse noise on the quality of transmission. In the paper we present results of a subscriber loop noise measurement survey conducted within GTE. Calibration for impulse-noise field measurements, which estimate impulse arrival rate λ and the standard deviation of the impulse amplitude distribution, σv, are also described. The effect of noise on the performance of a digitised loop is discussed.

DOI:10.1049/ip-f-1.1987.0082

出版商:IEE    

年代:1987

数据来源: IET

摘要:

A procedure for measuring the frequency shift and phase jitter of telephone data channels in the voice frequency band (300-3400 Hz) is presented. Rather than processing a received signal to obtain the required measurements, the phase is extracted and processed by a ‘phase filter’. An implementation of the phase filter is described which utilises power-2 coefficients to avoid the need for multiplication. This procedure is based on modern signal processing techniques which allow both simple and fast operation when implemented using a microprocessor. The technique can thus be easily incorporated into a telephone line measuring equipment or communication network monitoring system. Simulation results are given showing the effect of noise on the accuracy of the proposed algorithm, and some methods for the reduction of noise are also described. The trade-offs between the test signal duration and measurement accuracy are also considered.

DOI:10.1049/ip-f-1.1987.0083

出版商:IEE    

年代:1987

数据来源: IET

摘要:

A fast algorithm for measuring the frequency shift and phase jitter of telephone data channels which uses simple methods for extracting and processing the phase information of a received test signal was described in Part 1. A detailed analysis is now carried out for the Hilbert transformer and phase filter. The Hilbert transformer requires only one delay element, and two additions for each signal sample, and is thus attractive for general phase extraction applications with sinusoidal signals.

DOI:10.1049/ip-f-1.1987.0084

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The paper gives details of the performance and accuracy of the communications system monitor (CSM) which is used in conjunction with the Australian National Satellite System (AUSSAT). The equivalent isotropic radiated power (EIRP), frequency and carrier/noise ratio of all carriers are routinely monitored by the CSM as well as a range of baseband parameters for FM/TV and FDM/FM signals. The CSM capability to measure a number of satellite parameters and obtain remote antenna patterns is described. Details are provided of the accuracy of the CSM as determined during extensive factory testing. The results show that the CSM is a very accurate system for the monitoring of both satellite traffic and satellite transponder parameters. Procedures used for setting up carriers for the testing of the CSM are also included. The results presented are those obtained during extensive factory testing of the system. Following installation of the CSM additional carrier types and measurements have been incorporated in the system.

DOI:10.1049/ip-f-1.1987.0085

出版商:IEE    

年代:1987

数据来源: IET