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Matched-filter detection of binary signals is discussed in terms of the probability of bit error. The equations for the probability of error are derived for coherent phase shift keying, and coherent frequency shift keying (FSK). Suboptimum detection of FSK signals is also discussed for discriminators.
The bit error probability performance of a differentially-coherent phase-shift keyed (DPSK) modem with convolutional encoding and Viterbi decoding on time-varying fading channels is examined. Both the Rician and the lognormal channels are considered. 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.
Bypass circuit eliminates unwanted leakage in output RF signal. Correction circuit was developed for phase-shift-keyed transmitters. Principle can be adapted to correct leakage in other types of RF circuitry as well.
Relatively linear amplifier with automatic level control (ALC) preserves modulation characteristics of phase-shift-key (PSK) moculated S-band transmitter.
The paper discusses implementations of the carrier recovery loop for suppressed carrier binary phase shift keyed signals. The tracking performance of a practical squaring loop where the times-two multiplier is mechanized as a limiter/multiplier combination is developed. This produces the absolute value of the arriving signal which is practical in terms of low signal-to-noise ratios, a wide dynamic range of signal level, and temperature variations. The approach is compared to the usual squaring loop whose squaring circuit is the times-two multiplier exhibiting a square law characteristic.
A phase shift key (PSK) to BiO-L demodulator which uses standard digital integrated circuits is discussed. The demodulator produces NRZ-L, bit clock, and BiO-L outputs from digital PSK input signals for which the carrier is a 2 to the Nth multiple of the bit rate. Various bit and carrier rates which are accommodated by changing various component values within the demodulator are described. The use of the unit for sinusoidal inputs as well as digital inputs is discussed.
The cited articles from the international literature concern all aspects of communication satellite technology. Included are articles on satellite networks, data transmission efficiency, time division multiple access, data links, and phase shift keying. This bibliography contains 239 citations.
Quadriphase receivers, like biphase receivers, have the ability to false lock on a sideband on the data modulation. The theory associated with this phenomenon for receivers of binary phase-shift-keying (BPSK), using Costas loop demodulation, has recently been documented in the literature. This paper considers the corresponding theory for receivers of balanced quadriphase-shift-keying (QPSK) employing a quadriphase Costas loop (or equivalent fourth-power loop) for demodulation. Specific closed form expressions for false lock performance are developed and numerically evaluated for the particular case of single pole arm filters and an NRZ data format for each of the two statistically independent quadrature modulations.
The general analysis presented can be used to evaluate the performance of M-ary phase shift keying (MPSK) used over a nonlinear satellite channel in the presence of interference (CW tone and ISI) and channel noise. The numerical evaluation is based on the classical moment technique for approximating the probability distribution from moments of a random variable. The mathematical formulation of error probabilities of MPSK signals transmitted over nonlinear satellite repeaters is presented to include the effect of CW tone interference as well as the intersymbol interference. The approach is general and can be extended to include the effect of the synchronization.
An examination is conducted of the coded bit error rate (BER) performance of a satellite communication system in which binary phase-shift-keyed (BPSK) modulation is employed, pulsed CW or pulsed noise RFI is present, and the transponder contains a nonlinearity characterized by arbitrary AM/AM and AM/PM characteristics; the RFI pulse duration is further assumed to exceed that of the information symbol. Computed performance curves consider several hypothetical RFI scenarios in which either a hard limiter or an 8 dB clipper represent the transponder amplitude nonlinearity. Results demonstrate the potential seriousness of RFI duty cycles as low as 2 percent, and the fact that CW represents the most severe form of interference.
A digital demodulator for converting pulse code modulated data from phase shift key (PSK) to non return to zero (NRZ) and to biphase data is described. The demodulator is composed of standard integrated logic circuits. The key to the demodulation function is a pair of cross coupled one shot multivibrators and which with a flip-flop produce the NRZ-L is all that is required, the circuitry is greatly simplified and the 2(v) times bit rate contraint can be removed from the carrier. A flip-flop, an OR gate, and AND gate and a binary counter generate the bit rate clock (BTCK) for the NRZ-L. The remainder of the circuitry is for converting the NRZ-L and BTCK into biphase data. The device was designed for use in the space shuttle bay environment measurements.
This paper presents an analytical approach for assessing the effect of pulsed RFI on the error probability of a coherent phase-shift keyed signal through a nonlinear satellite repeater. The RFI is assumed to affect the uplink channel and to consist of CW pulses with random power levels and arriving randomly in time with a Poisson distribution. A model to approximate the effect of intermodulation products is introduced and the error probability conditioned on the output of the satellite repeater is computed. The classical moment technique is then used as an efficient method of averaging the conditional error probability over the numerous random parameters associated with the uplink signal.
This paper considers the performance evaluation of Staggered Quadrature Overlapped Raised Cosine (SQORC) signal transmission through wideband nonlinear satellite channels in the presence of uplink and downlink additive Gaussian noise. Expressions for the bit error rate are derived for a general transponder model with AM-AM and AM-PM conversion. It is shown that the bit error rate of SQORC is one-half of the sum of the bit error rate of MSK at 2/3 of the uplink signal-to-noise ratio and the bit error rate of Quadriphase Phase-Shift Keying QPSK at 4/3 of the uplink signal-to-noise ratio, whereas the spectrum of SQROC is the product of MSK and QPSK spectra. Numerical results are presented for a transponder which is modelled as a hard limiter.
Bandwidth efficient digital modulation techniques, proposed for use on and/or applied to satellite channels, are reviewed. In a survey of recent works on digital modulation techniques, the performance of several schemes operating in various environments are compared. Topics covered include: (1) quadrature phase shift keying; (2) offset - QPSK and MSK; (3) combined modulation and coding; and (4) spectrally efficient modulation techniques.
The means of telemetering digital data from a spacecraft to the Deep Space Network is addressed. Phase shift keying and uncoded quadriphase shift keying modulations are discussed along with demodulation and decoding systems. Telemetry system losses and noisy reference performance for suppressed carrier receivers are also examined.
The Communication Analysis Tool for the Space Station (CATSS) is a FORTRAN language software package capable of predicting the communications links performance for the Space Station (SS) communication and tracking (C & T) system. An interactive software package was currently developed to run on the DEC/VAX computers. The CATSS models and evaluates the various C & T links of the SS, which includes the modulation schemes such as Binary-Phase-Shift-Keying (BPSK), BPSK with Direct Sequence Spread Spectrum (PN/BPSK), and M-ary Frequency-Shift-Keying with Frequency Hopping (FH/MFSK). Optical Space Communication link is also included. CATSS is a C & T system engineering tool used to predict and analyze the system performance for different link environment. Identification of system weaknesses is achieved through evaluation of performance with varying system parameters. System tradeoff for different values of system parameters are made based on the performance prediction.
Any of six different data formats at any of five different data rates from phase-shift-key (PSK) modulated input signal extracted by digital radio receiver. Subcarrier Demodulator is Costas loop with hard limiter in inphase arm. There are six low-pass filters, each selectable for rate and format of data to be processed.
Using the S-band communications system, shuttle orbiter can communicate directly with the Earth via the Ground Spaceflight Tracking and Data Network (GSTDN) or via the Tracking and Data Relay Satellite System (TDRSS). The S-band frequencies provide the primary links for direct Earth and TDRSS communications during all launch and entry/landing phases of shuttle missions. On orbit, S-band links are used when TDRSS Ku-band is not available, when conditions require orbiter attitudes unfavorable to Ku-band communications, or when the payload bay doors are closed. the S-band communications functional requirements, the orbiter hardware configuration, and the NASA S-band communications network are described. The requirements and implementation concepts which resulted in techniques for shuttle S-band hardware development discussed include: (1) digital voice delta modulation; (2) convolutional coding/Viterbi decoding; (3) critical modulation index for phase modulation using a Costas loop (phase-shift keying) receiver; (4) optimum digital data modulation parameters for continuous-wave frequency modulation; (5) intermodulation effects of subcarrier ranging and time-division multiplexing data channels; (6) radiofrequency coverage; and (7) despreading techniques under poor signal-to-noise conditions. Channel performance is reviewed.