Showing papers on "Pulse-position modulation published in 1971"

Spatial Pulse Modulation

Abstract: Pulse modulation of electronic time signals is a well-proven concept, particularly in the context of data communications and computers. We suggest that pulse modulation of spatial optical signals might be another fruitful concept. The optical components and optical methods for performing the necessary operations for spatial pulse modulation are available. We demonstrate this experimentally by encoding a two-dimensional analog signal (an image) into a one-dimensional pulse signal. This might be of interest in connection with picture transmission over electronic channels, with cinematography, and with holography.

Variable-Length Redundancy Removal Coders for Differentially Coded Video Telephone Signals

Abstract: A study of the statistics of a differential pulse-code modulation coder for Picturephone® signals which uses a three-bit uniform length code suggests that a higher transmission efficiency can be obtained with a variable word length code. This permits an increase in number of quantizing levels used, thus improving picture quality. A quantizer with 24 levels rather than eight can be used provided that a buffer store of 10 000 bits is included in the system to smooth the irregular data flow caused by the varying code word length.

Pcm system including a pulse pattern analyzer

Abstract: A delta pulse code modulation system includes a feedback loop comprising a pulse pattern analyzer for detecting a large instantaneous modulation index within a fixed time interval. The system exhibits a wide range of modulation and suppresses whistling and interference tones at low pulse rates.

Digital-to-analog conversion apparatus and method

Abstract: An indirect digital-to-analog conversion apparatus and method which combines the advantages of pulse rate modulation with pulse width or pulse duration modulation. Pulse duration modulation is used on the least significant bits; while pulse rate modulation is used on the more significant bits up to the most significant bit. In this manner, the advantages of both systems are combined resulting in a system in which conversion time is minimized while the ripple content in the analog output is also minimized.

Multifunction audio digitizer

Abstract: An illustrative embodiment of the present invention includes apparatus which simultaneously produces both direct delta modulation and pulse code modulation. An input signal, after amplification, is supplied to a window comparator which supplies a polarity control signal to gate the output of a clock to the appropriate input of a binary up-down counter depending on whether the slope of the input signal is positive or negative. The control signals provide direct delta modulation while the up-down counter output provides pulse code modulation.

Optical modulation at high information rates

Abstract: This paper describes an optical modulation scheme with a demonstrated information rate of 1 Gb/s. The modulation scheme employs an electronic multiplexing technique to obtain the high data rate from four 250-Mb/s channels. Efficient interfacing between the gas laser beam and the high-speed electronic circuits is achieved using a traveling-wave type modulator structure. General considerations in optical modulation systems are also included.

Differential pulse code modulation system employing periodic modulator step modification

Abstract: In a differential pulse code modulation system, the integration of a pulse train representing a delta modulation coded format of an analog signal is modified by injection of at least one current of a magnitude corresponding to a predetermined fractional delta modulation step and of a polarity which indicates whether or not a delta modulation pulse was present in a predetermined phase of each recurring differential pulse code modulation accumulating period of the system. In a system coder, the initiation of the injected signal also causes the addition of a corresponding least significant bit to the accumulator output transmitted to a decoder. That least significant bit is utilized in the decoder to produce a corresponding current for injection into the equivalent integrating system of the decoder.

Exact model for delta-modulation processes

Abstract: A mathematical model is described which generates a pulse waveform identical to that of a single-integrator delta modulator, provided that the input signals to the latter do not cause slope overloading. The model uses analogue techniques of angle modulation and sampling to generate time- and amplitude-quantised signals, thus readily lending itself to exact analysis. The delta-modulation process is treated in a general manner that is equally applicable to delta-entry and sigma-entry systems. By this means, a central delta modem is defined which includes both pulse modulation and local decoding (prior to final filtering) of the pulse waveform. The model formulation is such that it is equivalent to the delta modem. The equivalence of the delta modem and model is proved analytically. It has also been verified by simulation on a digital computer and demonstrated experimentally. The model can be extended to simulate a double-integration network, provided that the necessary prediction is included. The model can also be extended to represent pulse-code modulation, because a linearly quantised p. c. m. siganal can be obtained by suitable sampling of the output of a delts modulator.

Comparison of several demand assignment multiple access/modulation techniques for satellite communications

Abstract: Comparison of demand assignment multiple access/ modulation techniques for satellite communication using high quality telephone channels

The Pulse Duration Modulator: A New Method of High-Level Modulation in Broadcast Transmitters

Abstract: A new approach for obtaining the audio power required for high-level plate modulation of AM broadcast transmitters is described. The advantages of this system are lower initial cost, broader frequency response, lower distortion, transmitter output adjustable from zero to full output, lower power consumption, fewer amplifier tubes, and lower operating cost.

Pulse amplitude modulation, frequency modulation telemetric data transmitter

Abstract: A data signal telemetry system having a pulse amplitude modulation subsystem, a video doppler subsystem, and a switchable external and internal power subsystem coupled and coacting to produce a composite signal of a plurality of information bits and a video signal of a target object or objects for transmission to remote points.

Pulse position modulation acoustic communications

Abstract: Pulse position modulation (PPM) is a simple and effective technique for transmitting information via the underwater acoustic channel. In this paper engineering design considerations for an underwater acoustic PPM system, including the location of threshold and the effects of multipath, attenuation, and time dispersion, are discussed. Techniques for calculating the required transmitter power, pulse repetition rate, and pulse width to communicate over some specified geometry are given.

Free running pulse position modulation system with receiver blanking

Abstract: The transmitter pulse is generated by an avalanche device triggered by the voltage developed across a capacitor charged from a constant current source. The timing of transmitter pulses is varied by varying the conductance of a device which shunts the capacitor in accordance with the modulating signal being transmitted. The receiver for the system is blanked, i.e., its input is closed to incoming signals, during intervals of predetermined duration immediately following detection of each transmitted pulse, making the receiver remarkably immune to noise during the intervals between incoming system pulses.

Digital communication system employing unity bit per sampling coding method

Abstract: A digital communication system reduces the transmission speed required to propagate signals resulting from a unity bit per sample coding process, e.g., delta modulation or delta-sigma modulation. The modulation wave pulses produced during cyclically recurring code converting intervals are counted and the count state transmitted rather than the modulation signal per se, thereby reducing the signal rate impressed on the communication channel. An inverse procedure is employed for signal recovery.