Showing papers on "Phase-shift keying published in 1973"
TL;DR: The results indicate that in Gaussian noise alone an improvement in signal-to-noise ratio of as much as 2 dB may be realized by using quadrature amplitude modulation instead of conventional amplitude and phase modulation.
Abstract: A long-standing communications problem is the efficient coding of a block of binary data into a pair of in-phase and quadrature components. This modulation technique may be regarded as the placing of a discrete number of signal points in two dimensions. Quadrature amplitude modulation (QAM) and combined amplitude and phase modulation (AM-PM) are two familiar examples of this signaling format. Subject to a peak or average power constraint, the selection of the signal coordinates is done so as to minimize the probability of error. In the design of high-speed data communication systems this problem becomes one of great practical significance since the dense packing of signal points reduces the margin against Gaussian noise. Phase jitter, which tends to perturb the angular location of the transmitted signal point, further degrades the error rate. Previous investigations have considered the signal evaluation and design problem in the presence of Gaussian noise alone and within the framework of a particular structure, such as conventional amplitude and phase modulation. We present techniques to evaluate and optimize the choice of a signal constellation in the presence of both Gaussian noise and carrier phase jitter. The performance of a number of currently used or proposed signal constellations are compared. The evaluation and the optimization are based upon a perturbation analysis of the probability density of the received signal given the transmitted signal. Laplace's asymptotic formula is used for the evaluation. Discretizing the signal space reduces the optimal signal design problem under a peak power constraint to a tractable mathematical programming problem. Our results indicate that in Gaussian noise alone an improvement in signal-to-noise ratio of as much as 2 dB may be realized by using quadrature amplitude modulation instead of conventional amplitude and phase modulation. New modulation formats are proposed which perform very well in Gaussian noise and additionally are quite insensitive to moderate amounts of phase jitter.
112 citations
TL;DR: A simple technique is presented for generating and optimally detecting the honeycomb (hexagonal.) signal set, i.e., the signal set that has the tightest sphere-packing properties and is shown to be slightly superior from an average power standpoint.
Abstract: Selection of a particular signal set array for a bandwidthConstrained multiple phase-and-amplitude-shift-keyed (MPASK) communication system for a linear additive Gaussian noise channel requires consideration of factors such as average and/or peak power versus symbol error probability, signal amplitude dynamic range, simplicity of generation and detection, and number of bit errors per symbol error (Gray code properties). A simple technique is presented for generating and optimally detecting the honeycomb (hexagonal.) signal set, i.e., the signal set that has the tightest sphere-packing properties. The symbol and bit error probability performance of this set is compared to other two-dimensional signal sets that have been investigated in the literature, and is shown to be slightly superior from an average power standpoint. The paper concludes with a comparison of all of these signal sets from the standpoint of the factors listed above.
93 citations
TL;DR: It is shown that with this method any desired accuracy can be theoretically achieved in the evaluation of the probability of error of M -ary phase-shift-keyed systems with Gaussian noise and intersymbol interference.
Abstract: A useful method is presented for the evaluation of the error probability of M -ary phase-shift-keyed systems with Gaussian noise and intersymbol interference By regarding a portion of the intersymbol interference as an equivalent Gaussian noise, this method suggests first calculating the probability of error caused by the combined effects of the Gaussian noise and the equivalent noise Necessary correction terms are then added to the calculation to take into account the fact that the intersymbol interference is actually non-Gaussian It is shown that with this method any desired accuracy can be theoretically achieved in the evaluation of the probability of error This method has been programmed for numerical computations Some examples are also given for illustrative purposes
52 citations
01 Jan 1973
TL;DR: Initial studies indicate that QASK offers significant raw dc-power savings over MPSK, despite the reduced transmitter efficiency, as well as multiple phase-and-amplitude modulation candidates.
Abstract: Bandwidth constraints in earth-satellite communication systems force consideration of uncoded M-ary modulation to obtain increased data rates. M-ary phase shift keying (MPSK) at first glance seems most promising because of the high transmitter efficiency achieved through Class C operation. Multiple phase-and-amplitude modulation candidates such as quadrature amplitude shift keying (QASK) appear less promising because the transmitter must operate at lower efficiency (in linear or multimode operation). However, initial studies indicate that QASK offers significant raw dc-power savings over MPSK, despite the reduced transmitter efficiency. For example, at S-band both solid-state and traveling wave tube (TWT) QASK transmitters can provide a 3-dB average dc-power savings over comparable 16-ary phase shift keying (PSK) for the same bit rate and error probability. The reason for this savings is that QASK requires much less average signal-to-noise ratio than 16-ary PSK for the same error rate.
9 citations
TL;DR: The relationships between bit error probability and transmitter power are presented on a common basis for various binary and m-ary modulation schemes operating with the same system data rate and the choice of modulation system under these conditions has been indicated.
Abstract: The relationships between bit error probability and transmitter power are presented on a common basis for various binary and m-ary modulation schemes operating with the same system data rate. it is assumed that the channel is disturbed by additive white gaussian noise of fixed power spectral density and that optimal matched filter reception is used. the results presented allow a comparison of the efficiencies of the systems in the use of transmitter power to provide a specified bit error probability. the theoretical bandwidth requirements of each system have been considered. sometimes the system designer is constrained to the use of an existing channel of fixed bandwidth and signal/noise ratio. the choice of modulation system under these conditions has also been indicated.
8 citations
Patent•
26 Jan 1973
TL;DR: In this paper, a circuit arrangement to eliminate the phase ambiguity at a receive terminal in phase-shift keying binary transmission systems is presented, where the received PSK binary signal is simultaneously applied to a conventional synchronous demodulator and a so-called nonambiguous demodulators which may be in analog or digital form.
Abstract: A circuit arrangement to eliminate the phase ambiguity at a receive terminal in phase-shift keying binary transmission systems. The received PSK binary signal is simultaneously applied to a conventional synchronous demodulator and a so-called nonambiguous demodulator which may be in analog or digital form. The outputs from both demodulators are compared to provide a signal having a first state when both demodulator outputs are in phase and having a second state when said demodulator outputs are in phase opposition. Logic means are provided to detect the state of the comparison signal in order to control inverter means adapted to reverse the demodulated original message from the synchronous demodulator when said comparison signal is in its second state.
8 citations
01 Jan 1973
TL;DR: This equation provides insight into why arrays differ in their signal-to-noise ratio requirements.
Abstract: This paper reviews the data rate, error rate, and signal-to-noise ratio relationship for various uncoded M-ary digital amplitude modulation (AM), phase modulation (PM), and combined AM-PM systems. These signal systems have the common virtue that expanding the number of possible signals to be transmitted increases the data rate but not the bandwidth. A general treatment of the error rate of M-ary digital AM-PM permits development of a simple yet accurate expression which approximates the increase in average signal-to-noise ratio (over that of binary phase shift keying) required for constant error performance. This equation provides insight into why arrays differ in their signal-to-noise ratio requirements.
6 citations
TL;DR: The relationship between system error probability and transmitter power is investigated for block and convolutional codes operating in conjunction with binary phase-reversal keying to give indication of the systems to be considered in order to achieve efficient use of transmitter power for given system bit error probabilities.
Abstract: The relationship between system error probability and transmitter power is investigated for block and convolutional codes operating in conjunction with binary phase-reversal keying. The following assumptions are made: (i) all systems accept the same data rate, (ii) a very large bandwidth expansion is not acceptable, (iii) the channel is disturbed by white Gaussian noise, (iv) a matched filter receiver is used.The performances of these coded systems are compared with those of optimal binary and M-ary modulation schemes to give an indication of the systems to be considered in order to achieve efficient use of transmitter power for given system bit error probabilities.
3 citations
TL;DR: The word error rate of an ensemble of cryptographic systems is determined and degradation is defined and computed for the case of phase-shift keying and white Gaussian noise.
Abstract: The word error rate of an ensemble of cryptographic systems is determined. The word error rate is specified as a function of the corresponding plain-text bit error rate. Degradation is defined and computed for the case of phase-shift keying and white Gaussian noise. Finally, the effect of differential encoding on a cryptographic system is investigated.
3 citations
11 Sep 1973
TL;DR: In this article, the results of a theoretical and experimental study of the relative strengths and weaknesses of amplitude shift keying, phase-shift keying and quadri-phase shift-keying systems are summarized.
Abstract: : The report summarizes the results of a theoretical and experimental study of the relative strengths and weaknesses of amplitude shift keying, phase shift keying and quadriphase shift keying systems. The report is a combination review report and research monograph. Ideal theoretical results are discussed, and methods of practical realization are described. New research results include the determination of the standard deviation of the arrival time as a function of modulation, simple formulas for the degradation in both digital and analog systems due to adjacent-channel interference, and simple upper bounds for intersymbol interferences. The use of the formulas are all examined experimentally.
1 citations
TL;DR: A multiple branch predetection combining diversity receiver technique using pulse-envelope modulation of the transmitted signal is described, and each branch can be shown to be mathematically equivalent to a simple square-law detector.
Abstract: A multiple branch predetection combining diversity receiver technique using pulse-envelope modulation of the transmitted signal is described The receiver branches use the "STAR" scheme of multiple heterodyning of the received signal with itself to eliminate all exponential modulation components imparted by the transmission medium Each branch can be shown to be mathematically equivalent to a simple square-law detector A modulation scheme using low-bit-rate (50 kHz) companded delta modulation is proposed which provides a reasonable output signal-to-noise ratio (30-40 dB) The convenience of received signal gain control before pulse regeneration and the possible application of conjugate phase retransmission could make this technique useful
TL;DR: The SCPDM technique is shown to be extremely useful and cost effective where the overall objective is to obtain maximum traffic rather than toll quality voice communication.
Abstract: A highly efficient subcarrier modulation technique, suppressed clock pulse duration modulation (SCPDM) has been developed that outperforms narrow-band frequency modulation in very noisy channels. Developed primarily for hard limiting satellite repeaters, the technique utilizes a phase-shift key (PSK) carrier and phase-lock demodulators. The SCPDM technique is shown to be extremely useful and cost effective where the overall objective is to obtain maximum traffic rather than toll quality voice communication. Design considerations are discussed and test data from a typical hardware implementation are presented.