Showing papers on "Phase-shift keying published in 1977"

Introduction to Communication Systems

Abstract: 1. Introduction. 2. Orthogonality and Signal Representations. Signals and Systems. Classification of Signals. Classification of Systems. Signals and Vectors. Orthogonal Functions. Choice of a Set of Orthogonal Functions. The Exponential Fourier Series. Complex Signals and Representations. The Trigonometric Fourier Series Representation. Extension by Periodicity. Parseval's Theorem for Power Signals. The Frequency Transfer Function. Steady-State Response to Periodic Signals. Harmonic Generation. The Fourier Spectrum and Examples. Numerical Computation of Fourier Coefficients. Effects of Alias Terms. Singularity Functions. Impulse Response. Convergence of the Fourier Series. Summary. Problems. 3. The Fourier Transform and Applications. Representation of an Aperiodic Function Over the Entire Real Line. The Spectral Density Function. Existence of the Fourier Transform. Parseval's Theorem for Energy Signals. Some Fourier Transforms Involving Impulse Functions. Properties of the Fourier Transform. Some Convolution Relationships. Graphic Interpretation of Convolution. Filter Characteristics of Linear Systems. Transversal Filters. Bandwidth of a System. Requirements for Distortionless Transmission. Time Response of Filters. Minimum Time-Bandwidth Product. The Sampling Theorem. Aliasing Effects in Sampling. The Discrete Fourier Transform. The Fast Fourier Transform. Summary. Problems. 4. Spectral Density and Correlation. Energy Spectral Density. Power Spectral Density. Time-Averaged Noise Representations. Correlation Functions. Some Properties of Correlation Functions. Correlation Function for Finite-Energy Signals. Band-Limited White Noise. Summary. Problems. 5. Amplitude Modulation. Amplitude Modulation: Suppressed Carrier. Amplitude Modulation: Large Carrier (AM). Frequency-Division Multiplexing (FDM). Single-Sideband (SSB) Modulation. Vestigial-Sideband (VSB) Modulation. A Time-Representation of Bandpass Noise. Signal-to-Noise Ratios in AM Reception. Propagation Effects. Comparison of Various AM Systems. Summary. Problems. 6. Angle Modulation. FM and PM. Narrowband FM. Wideband FM. Average Power in Angle-Modulated Waveforms. Phase Modulation. Generation of Wideband FM Signals. Demodulation of FM Signals. Signal-to-Noise Ratios in FM Reception. Threshold Effect in FM. Signal-to-Noise Improvement Using Deemphasis. Summary. Problems. 7. Pulse Modulation. Pulse-Amplitude Modulation (PAM). Time-Division Multiplexing (TDM). Pulse Shaping and Intersymbol Interference. Other Types of Analog Pulse Modulation: PWM and PPM. Signal-to-Noise Ratios in Analog Pulse Modulation. Pulse-Code Modulation (PCM). Fiber Optic Communication Systems. Use of Parity and Redundancy in PCM. Time-Division Multiplexing of PCM Signals. Integrated Services Digital Network (ISDN). The Matched Filter. Matched-Filter Codeword Detection. Pseudonoise (PN) Sequences. Summary. Problems. 8. Probability and Random Variables. Probability. Conditional Probability and Statistical Independence. The Random Variable and Cumulative Distribution Function. The Probability Density Function. Statistical Averages. Some Probability Distributions. The Histogram. Transformations of Random Variables. Joint and Conditional Density Functions. Correlation Between Random Variables. The Bivariate Gaussian Distribution. Random Processes. Autocorrelation and Power Spectra. Numerical Computation of Power Spectra. Summary. Problems. 9. Information and Digital Transmission. A Measure of Information. Channel Capacity. Ideal Demodulator Detection Gain. Quantization Noise. Probability of Error in Transmission. S/N Performance of PCM. Delta Modulation and DPCM. Error Analysis of PCM Repeaters. Power Spectral Densities of Data Waveforms. Partial-Response Signaling. Equalization. M-ary Signaling. Coding for Reliable Communication. Summary. Problems. 10. Digital Modulation. Amplitude-Shift Keying (ASK). Frequency-Shift Keying (FSK). Phase-Shift Keying (PSK). Comparison of Binary Digital Modulation Systems. Direct-Sequencing Spread Spectrum Systems. Quadrature AM (QAM) and Quaternary PSK (QPSK). Continuous-Phase FSK (CPFSK) and Minimum-Shift. Keying (MSK). M-ary Orthogonal FSK. Frequency-Hopping (FH) Spread Spectrum Systems. M-ary PSK. Amplitude-Phase Keying (APK). Comparison of Digital Modulation Systems. Representation of Digital Waveforms. Optimum Detection Algorithms. Summary. Problems. Appendix A: Selected Mathematical Tables. Appendix B: Decibels. Appendix C: Broadcast Frequency Bands. Appendix D: Commercial Television Transmission. Appendix E: Telephone Channels. Appendix F: Some Commercial Preemphasis/Deemphasis Systems. Appendix G: A Table of Bessel Functions. Appendix H: Stereo AM. Appendix I: A Table of Gaussian Probabilities. Index.

A Look at Crosstalk in Quadrature-Carrier Modulation Systems

Abstract: A method is presented for comparing the performance of different quadrature-carrier modulation techniques. It is based on the calculation of the mean-square crosstalk between adjacent digital communications channels. This method was used to determine the crosstalk of a number of constant envelope modulation schemes, including Staggered Quaternary Phase Shift Keying (SQPSK) and Minimum Shift Keying (MSK). The results, as have previous results, show the improved performance of MSK over SQPSK. By utilizing the general equation for mean-square crosstalk as a measure of performance, a search was made for constant envelope modulation methods with reduced crosstalk. A number of methods were found which have better mean-square crosstalk performance than MSK. Finally this paper presents a method for reducing degradation due to crosstalk by using mismatched windows in the standard correlation detector. An example of this technique for detection of MSK signals is analyzed.

MLD and mse algorithms for adaptive detection of digital signals in the presence of interchannel interference

Abstract: Adaptive mean-square error (mse) and maximum-likelihood detection (MLD) algorithms for a dual-channel digital communication system in the presence of interchannel interference and white Gaussian noise are presented. The mse algorithm forms estimates of the transmitted symbols from a linear combination of received symbols using weights that minimize the mse between transmitted and estimated symbols. The nonlinear MLD algorithm minimizes the probability of symbol error by maximizing the probability of the received signal samples on the two channels over ail possible transmitted symbol pairs. The probability of error is derived for the two algorithms when quadrature phase-shift keying (QPSK) is used as a modulation technique, and is compared with that of a dual-channel QPSK system having no compensation for the crosstalk.

Optimization of Coded Spread Spectrum System Performance

Abstract: Error correction coding techniques significantly improve performance of spread spectrum communication systems in environments containing jamming, multipath, and unregulated multiple access. This paper investigates the optimization of spread spectrum system performance for time-varying unknown interference. Noncoherent frequency hopping (FH) spread spectrum modulation, and hybrid FH-PN incorporating a direct sequence PN modulation on each hopped frequency are studied. For FH or FH-PN, the data modulations considered are differential phase-shift-keying (DPSK), differential quadriphase-quadriphase-shift-keying (DQPSK), and multiple-frequency-multiple-frequency-shift-keying (MFSK). Both block and convolutional error correction coding techniques are studied as a means of improving the spread spectrum performance.

PSK-Type Modulation with Overlapping Baseband Pulses

Abstract: One of the most interesting challenges in the field of digital radio is to generate and transmit signals which meet the spectral requirements and which have high detection efficiencies. The spectral efficiency of PSK-type modulation with overlapping baseband pulses is known to be better than that with nonoverlapping pulses of the same form; but, to our knowledge, no analysis is presently available to determine their detection efficiency. In this paper a method has been given to evaluate the error probability performance of PSK-type modulation with baseband pulses of finite overlap and mutually independent samples. It is shown that the error probability can be computed with any desired accuracy. For BPSK and for some typical transmit and receive filters and for a transparent channel corrupted by additive Gaussian noise we compare the detection efficiencies when the baseband modulation pulses have zero and nonzero overlap and when the transmitted signal satisfies the same spectral requirement. The nonoverlapping rectangular signaling is shown to be superior to overlapping raised-cosine signaling, but the differential degradation is less than 0.8 dB if the twosided 99-percent bandwidth W 99 satisfies 1.1/T \leq W_{99}\leq 1.6/T . The analytical results presented here for a binary system can be extended with minor modifications to any M -ary PSK system, M > 2 .

Performance of DPSK with Convolutional Encoding on Time-Varying Fading Channels

Abstract: The bit error probability performance of a differentiallycoherent phase-shift keyed (DPSK) modem with convolutional encoding and Viterbi decoding on time-varying fading channels is examined. We consider both the Rician and the lognormal channels. Bit error probability upper bounds on fully-interleaved (zero-memory) fading channels are derived and substantiated by computer simulation. It is shown that the resulting coded system performance is a relatively insensitive function of the choice of channel model provided that the channel parameters are related according to the correspondence developed as part of this paper. Finally, a comparison of DPSK with a number of other modulation strategies is provided.

A Worst-Case Crosstatk Comparison Among Several Modulation Schemes

Abstract: The effects of worst-case crosstalk (from a time-domain point of view) on unsynchronized frequency division multiplexed (FDM) constant envelope modulations are considered assuming coherent hard-decision receivers and no filtering for bandwidth constraint. Continuous-phase frequency shift keying (FSK) is found to be superior to various forms of phase shift keying (PSK).

A Digital Filter-Modulation Combination for Data Transmission

Abstract: It is shown that it is possible to generate a band-limited PSK signal using a ROM and a four-quadrant multiplying D/A Converter.

M-ary PSK transmission via a coherent two-link channel exhibiting AM-AM and AM-PM nonlinearities

Abstract: This paper generalizes some aspects of Jain and Blachman's analysis of the error probability for binary PSK transmission over a two-link channel having a hard-limiting repeater. In the present analysis M -ary PSK transmission through a repeater having both nonlinear amplitude and phase characteristics is considered. The error probability is given in terms of an infinite series whose n th term must be obtained by a one-dimensional numerical integration. A practical amplitude and phase characteristic from the literature is treated. Also presented is a study of the effect on error probability of "backing-off" the repeater from saturation.

4-phase p.s.k. differential demodulator using a.s.w. delay lines

Abstract: The letter describes a cheap and reliable solution, using acousticsurface-wave delay lines, for the differential demodulation of phase-shift-keyed digital signals at low digital rates (up to 20 Mbit/s). Results on 4-phase p.s.k. differential demodulators operating at 2.048 Mbit/s are reported in terms of bit error rate against energy per bit/noise spectral density ratio. In addition, using the same technology, a new multidifferential demodulator has been implemented. Owing to multiple differential demodulations carried out on the same signal, a significant improvement in both theoretical and experimental bit error rate is obtained.

On Improving Bit Error Probability of QPSK and 4-Level Amplitude Modulation Systems by Convolutional Coding

Abstract: We consider Amplitude Modulation (AM) systems, PhaseShift-Keying (PSK) and Amplitude-Phase-Keying (APK) systems in which each symbol can take 2nvalues. After a systematic search of (n, n - 1) binary convolutional codes with large values of free distance and minimal number of code words at that distance, simulations have been performed with an 8-symbol modulation system ( n = 3 ). For a bit error probability of less 2 \times 10^{-4} , the saving in average power signal-signal-to-noise ratio over that required for an uncoded system with the same channel symbol rate was more than 2 dB with PSK and APK, and 1.5 dB with AM.

Frequency modulation and variable-slope delta modulation in SCPC satellite transmission

Abstract: This paper analyzes and presents subjective assessments of the performance that can be expected with FM, companded FM, and vaniable-slope delta modulation in single-channel-per-carrier (SCPC) service to small earth stations. In addition, it points out some of the problems that may be encountered in applying FM and digital techniques to an operational system.

Clock extraction device for double-binary phase-shift keying system

Abstract: A circuit for extracting a clock signal from a double-binary phase-shift keying system is disclosed. The carrier wave form is regenerated at the receiver from the phase-shift keyed (PSK) signal input. The regenerated carrier wave is frequency doubled and frequency mixed with the PSK input signal which has also been frequency doubled. A desired clock signal is thereafter extracted from the mixed signal by a band-pass filter. The system does not include a frequency divider which would result in a phase ambiguity.

The Effect of Carrier Phase Error on the Performance of a Duobinary Shaped QPSK Signal

Abstract: An analysis is presented showing the effect of carrier phase error on the error-rate of a duobinary shaped, quaternary, phaseshift keying digital radio system. A simple upper bound on the probability of error as a function of phase error is derived and the results are compared to those obtained by computer simulation. The conclusion is reached that such a system exhibits approximately 1.0 dB degradation for a carrier phase error of 3° at an error-rate of 10-5and a 10 dB degradation at a phase error of 15°.

Consideration of 8-Phase CPSK-TDMA Signal Transmission Through Band-Limited Satellite Channels

Abstract: The performance of 90- and 108-Mbit/s 8-phase CPSKTDMA channels through a 36-MHz-bandwidth transponder has been evaluated. At the optimum operating point, the error rate of the 90Mbit/s channel is improved by about one order of magnitude relative to that of the 108-Mbit/s channel, and the corresponding carrier power saving is about 3.5 dB. Measurements through a linearized TWT indicate that such a TWTA may be driven harder than a conventional TWTA with a substantial saving in the transponder RF power output. The potential of 8-phase CPSK-TDMA signal transmission through band-limited satellite channels using linearized TWTA's onboard the satellite and modems of the latest technology appears attractive.

22phase psk transmitter

Abstract: PURPOSE:To obtain 2-phase PSK (Phase Shift Keying) transmitter which features narrow occupied band width and high-efficiency large output with use of Cclass non-linear amplifier as the amplifier.

Error Rate Bounds for Digital PAM Transmission with Phase Jitter and Intersymbol or Cochannel Interference

Abstract: A simple method is presented for computing upper and lower bounds for binary PAM signaling over channels with phase jitter. Other impairments to reliable communication are taken to be additive thermal noise and intersymbol or cochannel interference. The important cases of binary and quadrature phase shift keying are cases for which the analysis presented is valid. The method consists of finding upper and lower bounds conditioned on the phase jitter, φ, in a form in which the auguments of the Q -functions involved are linear in \cos \phi and \sin \phi . When these functions are represented by a piecewise linear approximation, the average of these bounds can be given in closed form. In most cases 5 piecewise linear segments provides an error rate estimate that is accurate to at least 1 dB in system signal-to-noise ratio (SNR).

Carrier synchronization techniques for unbalanced QPSK signals. II

Abstract: This paper develops a theory for assessing the tracking performance and designing carrier synchronization loops which are to be matched to an unbalanced QPSK signal design. It is assumed that the power split and the I and Q channel data rates are arbitrary. Bit synchronization is assumed to be unavailable for both carrier reconstruction techniques which have been suggested via MAP estimation theory. Numerical results are presented.