Showing papers on "Pulse-position modulation published in 1977"

Low-power, infrared information transmission system

Abstract: A low-power infrared information transmission system, the transmitter of which is compact, portable and capable of being powered by a low-voltage battery power source for an extended period of time, utilizes a unique infrared light pulse position modulation technique. The system is capable of transmitting information from a DC signal to a relatively high frequency AC signal. The system is utilized, for example, to transmit medical information from medical electrodes affixed to a patient via a portable infrared transmitter to a receiver unit which monitors and analyzes the patient's condition; to provide a remote control unit such as the controller for a video game or a TV on/off/channel selector, and, to provide a portable communications device such as a portable microphone or telephone set.

Optical Pulse Position Modulation with Multiple Positions per Pulsewidth

Abstract: This concise paper determines the required laser power to achieve a given probability of bit error using a pulse-interval modulation (PIM) (discrete pulse position modulation) system with resolution much smaller than a laser pulsewidth. An approximation to the first crossing density for a threshold detector operating on a filtered Poisson process is used. Both analytic and computer simulation results are presented.

Analog Versus Digital Antijam Video Transmission

Abstract: This paper presents an evaluation of the relative performance provided by analog and digital video modulation approaches. Antijam (AJ) performance of these modulations is considered when used in concert with spread-spectrum techniques such as frequency hopping, and direct sequence pseudorandom modulation. These modulation approaches are compared on the basis of power efficiency, required channel bandwidth, and degree of AJ protection for the same output video quality. The effect of video bandwidth compression and reduction techniques on the relative modulation performance is also presented. A description of an RCA-developed wide-band video AJ system, based on the results of this study, is also included.

Pulse position modulation system

Abstract: PURPOSE:Development of a pulse position modulation system of simple reference pulse position setting and less fluctuation of pulse density.

Nonuniform Pulse Code Modulation Encoder using Double Polysilicon Technology

Abstract: A new monolithic PCM-encoder is presented. It essentially consists of a single eleven bit double polysilicon capacitor array and an improved multiple access comparator. No unity gain amplifier is required. The circuit meets the CCIT specifications.

A low-bit-rate speech coding system using a low cost stack architecture microprocessor

Abstract: A real-time Adaptive Differential Pulse Code Modulation (ADPCM) system is described which employs an inexpensive, currently about $25, stack-architecture microprocessor. The coder operates at 3 bits/sample and a 10 KHz rate and performs all processing between the taking of input speech samples. The ADPCM tables are stored in the stack for rapid manipulation of table column and row pointers allowing implementation of real-time operation.

A review of delta modulation systems

Abstract: 355 to consider speech to be an all-pole process. This oversimplification of what is actually known about speech encourages belief that all-pole linear prediction can lead to an exact representation. The finite duration of individual glottal pubes and the antiresonance characteristics of the nasal tract prevent true representation and the reader should not be misled. As noted by the authors, there are current efforts at combined pole-zero estimation using linear prediction. However , the reader should not despair at this criticism of the current state of affairs: the chapters on applications illustrate the many productive uses of all-pole linear prediction for speech communication and parameterization. \" Automatic Formant Trajectory Estimation, \" \" Fundamental Frequency Estimation, \" and \" Vocoders \" are covered in the chapters with those titles. As elsewhere throughout the book, the discussion is accompanied by computer programs so that the reader may rapidly establish and use the techniques. As in the mathematical sections, the authors feature their own work and that of their-lose colleagues, but there is ample discussion of and reference to competing opinions and procedures. It should be noted that the power of linear prediction has not relieved one from the aforementioned reliance on special rules and heuristic procedures in processing speech. Up to this point in the review, only some, seemingly more important, topics from the total covered by the authors have been discussed. This raises the question of completeness which, if one is to follow the generalistic tone set in the first paragraph, should be answered for the area of linear prediction of speech, not just for the book. This can start with a game to see if the authors have identified all the different problem formulations leading to linear prediction , starting with Prony's work in 1795. In Chapter 2, \" Formulations, \" they cover a goodly number, taking the reader over minimum variance and maximum likelihood, time averages and ensemble averages, as well as correlation functions and Gaussian density functions.. However, they can be one-upped by citing Berg's work on entropy [ 1 ]. A review of the topic of linear prediction of speech identifies at least two areas which merit more attention: prediction of fixedduration frames with varying coefficients and prediction by continuously adaptive methods. Both areas converge to the consideration of continually changing coefficients. Liporace has developed the mathematical relationships for expressing the usual prediction coefficients as sums of …

Effect of emphasis on threshold in angle modulation systems

Abstract: Emphasis can be used in angle modulation systems (frequency and phase modulation) to improve receiver output signal-to-noise ratio (SNR). It is shown that the threshold input SNR increases when emphasis is used. The increase may be well over one decibel, depending on system parameters, when the message is Gaussian and random.