The Effect of Phase Error on DPSK Error Probability

Expressions are found for the effect of an error in the delay of the preceding signal, which provides the reference phase for the decoding of the present signal in differential phase-shift-keying reception. The signal-to-noise ratio is allowed to be different for the two signals that are compared by the receiver's phase detector. The results are applicable to both binary and quaternary DPSK. In addition, an approximation is obtained for the error probability when the two Signal-to-noise ratios are equal to the same large value.     

The Effect of a Nonlinearity upon Signals in the Presence of Noise

A general method is presented for determining not merely the output spectrum resulting from a nonlinear transformation of signals and noise but also the signal × signal distortion and intermodulation components, including their phases and their precise forms as functions of time. Recent work by Jain is thereby illuminated and generalized.     

Interference suppression by biased nonlinearities

It is shown that, when the input signal-to-interference ratio (SIR) is small, a biased nonlinearity that has a dead zone below some threshold value can provide a large enhancement in output SIR and signal-to-interference-plus-intermodulation ratio (SIIMR) if the threshold is set equal or close to the amplitude of the strong interference. In the absence of noise, the output SIR and SIIMIR are virtually independent of the input SIR, however low the latter may be. It Is shown that, for a dead-zone limiter, the output SIIMR in this case is -4.93 dB regardless of the input SIR. Under strong interference, any noise present in the input reduces the SIR and SIIMR improvement, but a biased nonlinearity can still provide an output SIR and SIIMR superior to the input SIR, i.e. an output SIIMR 6.35 dB below the input signal-to-noise ratio (SNR) instead of 6.02 dB below the input SIR as is the case with hard limiting     

F.M. click rates: a simple derivation

A firm foundation is given to Roberts's simple calculation of Rice's results that account for the effect of modulation on the click rate in f.m. reception.     

Gaussian noise. 1. The shape of large excursions

Work on the parabolic shape of the topmost part of high noise peaks is extended to show that these peaks are all approximately proportional to the autocorrelation function, R( tau ), of the noise. It is shown that the large excursions of the envelope of narrowband Gaussian noise also tend to have the shape of the envelope of its autocorrelation function.<>     

The spectrum of the square of a synchronous random pulse train

Novel forms are derived relatively simply for the spectrum of the square of a synchronous random pulse train. The lines in the discrete part of the spectrum are useful for bit and carrier synchronization in digital communication systems, whereas the continuous part of the spectrum limits the signal-to-noise ratio available in any given bandwidth from the spectral lines. The application of the formulas derived and some conclusions are discussed     

Third-Order Intermodulation Due to Quantization

When an input consisting of a strong signal and a weak signal is handled digitally, the resulting quantization introduces not only noise and distortion of the stronger signal (which have been thoroughly studied elsewhere) but also intermodulation between the two. Third-order intermodulation is the principal source of spurious inband signals, and it is important, therefore, to determine its strength in comparison with that of the true weak-signal output, which is of the same order of magnitude. The assumption that the weaker signal's amplitudeais very much smaller than the quantization step size permits a relatively simple analysis by means of two different approaches. Both of them lead to a finite series for the amplitudec_{2}aof the intermodulation. This series is easily evaluated numerically, but simple approximations obtained by truncation of Euler's summation formula show the behavior of c2more clearly as a function of the amplitude of the stronger input and will be found adequate for most applications.     

Transform related to spherical distributions and its inversion

For describing the envelope and the values of a narrowband random noise Roberts uses the probability distribution of the length of a vector independently distributed uniformly in direction and the probability distribution of the length of a projection of this vector. The latter distribution is expressed in terms of the former, and a simple form is found for the inverse of this relationship.<>     

Phase and logarithm of amplitude of a signal plus noise

The mean and variance of the logarithm of the amplitude of a signal plus noise are discussed. Ward and Tough's (see ibid., vol.24, no.2, p.85-7, 1988) explanation for the very small bias of this mean at high signal-to-noise ratios is shown to be closely related to the capture effect in FM reception     

Relationship of rapid naming ability and language analysis skills to kindergarten and first-grade reading achievement.

34 kindergartners and 34 1st graders completed a series of measures including the McCarthy Scales of Children's Abilities and the WRAT. Language analysis tasks (segmentation and rhyming) and rapid automatized naming tasks (objects, colors, and letters) were found to tap different components of linguistic processing in both kindergarten and 1st-grade Ss. In kindergarten, rapid naming of colors was significantly related to 5 of 6 reading measures, whereas rapid naming of objects, syllable segmentation, and rhyming were related to at least 3 of the 6. In the 1st grade, rapid naming of letters and phoneme segmentation were significantly related to all 3 measures of 1st-grade reading achievement. Ss who could analyze letter names (as indicated by speed on the letter naming task) were more likely to be among the better readers at the end of the 1st grade. (66 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)