Showing papers on "Pulse-position modulation published in 1975"
TL;DR: In this paper, the authors compare traditional plate modulation and modified Doherty and modified Chireix (Ampliphase) moduladon modulation schemes in commercial AM broadcast transmitters.
Abstract: From the beinning, plate moduladon has been the dominant method of modulation used in commercial amplitude-modulation (AM) broadcast transmitters. Recently, however, alternate modulation schemes have been employed in commercial transmitters in growing numbers, namely, pulse-duration modulation (PDM), modified Doherty, and modified Chireix (Ampliphase). This paper discusses traditional plate modulation and compares it, critically, to the newer methods being employed. Performance parameters and economic factors of each of the systems are reviewed and compared. A tutorial approach is used.
48 citations
Patent•
03 Jan 1975
TL;DR: In this article, the positions of the various control sticks are represented by a digital code which is multiplexed and then transmitted via pulse code modulation of a unique subcarrier signal.
Abstract: A pulse code modulation communication system adapted in a preferred embodiment to the remote control of a flying model aircraft. The positions of the various control sticks are represented by a digital code which is multiplexed and then transmitted via pulse code modulation of a unique subcarrier signal. The unique subcarrier signal is locked onto by the receiver which, through correlation detection, detects and demultiplexes the digital code for use by the servo motors to position the flight control surfaces of the aircraft.
17 citations
TL;DR: This work considers the design of a receiver for a digital optical fiber system operating with multilevel pulse amplitude modulation, which provides for high bit rates on digital systems employing large diameter optical fibers and LED sources.
Abstract: We consider the design of a receiver for a digital optical fiber system operating with multilevel pulse amplitude modulation This form of modulation provides for high bit rates on digital systems employing large diameter optical fibers and LED sources The receiver configuration analysis is one with a p-i-n avalanche photodetector and a FET preamplifier The analysis is complicated by the fact that the signal levels and threshold boundries have to be nonuniformly spaced to cope with signal dependent shot noise introduced by the photodiode detector An algorithm for level placement is reported Performance figures for typical systems, with optical pulse shape which are either Gaussian or exponential, are calculated
13 citations
TL;DR: Data show, with each scheme, peak-signal-to-rms-noise ratios of 70 dB can be achieved with the required average optical power at the receiver being − 73 dBm with a pin detector and − 88dBm with an avalanche detector.
Abstract: This paper describes an optical-frequency pulse-position-modulation experiment using a GaAs luminescent diode as the source and either a pin or an avalanche photodiode as the detector. The experimental system transmits an audio band from 300 Hz to 3.4 kHz at an 8-kb/s repetition rate. Timing synchronization between the transmitter and receiver has been accomplished by two methods: by transmitting a separate clock signal and by recovering the timing from the ppm signal itself. Data show, with each scheme, peak-signal-to-rms-noise ratios of 70 dB can be achieved with the required average optical power at the receiver being − 73 dBm with a pin detector and − 88 dBm with an avalanche detector.
10 citations
TL;DR: Tests of the transmission of data over single- and multiple-hop companded delta modulation systems indicate that the two systems are comparable for error-free digital lines but favors the DM system for lines with errors.
Abstract: This paper reports upon the results of tests of the transmission of data over single- and multiple-hop companded delta modulation (DM) systems. The DM coder-decoder (CODEC) was optimized for voice transmission. Modem bit error rate (BER) achievable over the range of 1200-9600 bits/s is presented. A comparison with the performance of pulse code modulation (PCM) is included. The comparison indicates that the two systems are comparable for error-free digital lines but favors the DM system for lines with errors.
4 citations
TL;DR: A method for analyzing the binary signal produced by pulse position modulation and pulse width modulation and a method of using a combination of PPM and PWM to make binary Fourier transform holograms of digital data is presented.
Abstract: A method for analyzing the binary signal produced by pulse position modulation (PPM) and pulse width modulation (PWM) is presented. The results are used to study the conversion of analog signals into binary waveforms. The Fourier transform is a complex analog signal. A method of using a combination of PPM and PWM to make binary Fourier transform holograms of digital data is presented. Two optical methods for reading out the optically recorded PPM signals are discussed. Experimental results demonstrate the different aspects of these modulation techniques for optical storage.
1 citations
01 Jan 1975
TL;DR: Some of the subtle differences between the 4-phase PSK and the Fast FSK, their spectral occupancy, and between the circuitry which "self synchronizes", i.e. regenerates carrier phase and clock references at their receivers are discussed.
Abstract: The 4-phase PSK and the Fast FSK are two different digital modulation systems; both perform well when it is required to conserve power as well as bandwidth. This report discusses some of the subtle differences between their signal structures, their spectral occupancy, and between the circuitry which "self synchronizes", i.e. regenerates carrier phase and clock references at their receivers.