Showing papers on "Delta-sigma modulation published in 1969"

The application of delta modulation to analog-to-PCM encoding

Abstract: This paper describes a pulse code modulation (PCM) encoder that employs a delta modulator as the analog-to-digital converter A tapped binary shift register and an up-down counter cause delta modulation signals to be converted to a uniformly quantized PCM format When tap weights are optimized with respect to a minimum mean square error criterion, the number of shift register stages necessary to obtain a fixed level of output quantizing noise varies inversely with delta modulation sampling rate Because the tap weights may be rounded to a modest number of binary places, the arithmetic operations are simple to implement A significant portion of the delta modulation-to-PCM converter may be time shared among several signals

Delta modulation granular quantizing noise

Abstract: We present a statistical analysis of a single integration delta modulation system in which slope overload effects are negligible. In defining the delta modulation signal ensemble, we identify a binary phase parameter and show that when this parameter is random, the signal statistics are stationary, provided the input is stationary. Thus the delta modulation correlation functions depend on a single time variable and have Fourier transforms that are the power spectra of the delta modulation signals. After deriving the delta modulation correlation statistics and power density spectra, we use these functions to investigate the properties of the delta modulation granular quantizing noise. We demonstrate the ratio of input signal power to the quantizing noise power of three signals that approximate the system input. These signals are the integrated delta modulation signal, the signal at the output of the ideal low-pass interpolation filter usually considered in delta modulation studies, and the signal at the output of the optimum interpolation filter. We determine the properties of this filter by referring to the derived spectral density functions.

The state-variable approach to continuous estimation with applications to analog communication theory

Abstract: Monograph on state variable approach to continuous estimation of random processes with applications to analog communication theory

Device for analog to digital conversion or digital to analog conversion

Abstract: In a successive approximation for converting analog data to digital form or digital data to analog form, the logically programmed sequence is switched at ground potential in order to eliminate transients of the type usually introduced by switching. In order to ensure great conversion accuracy, a voltage source is provided for generating precision reference signals that are extremely unresponsive to input voltage fluctuations.

Signal detection apparatus

Abstract: A receiver for use in a system in which randomly varying targetindicating signals from a transducer are detected in the presence of noise signals which may vary in amplitude between wide limits. Advantage is taken of the fact that the spectrum of frequencies of randomly varying target-indicating signals differs from the spectrum of frequencies of noise signals. Therefore, by appropriately multiplexing and filtering the signals from a transducer, separate signals proportional, respectively, to the root mean square value of noise signals and target-indicating signals may be derived and compared to produce an output signal which changes from one level to another when target-indicating signals are present.

Analog/digital differential apparatus for comparing resolver output data with a digital signal

Abstract: Apparatus for comparing an analog input signal with a digital input signal and providing an analog output signal proportional to the difference therebetween, said apparatus comprising an analog/digital differential controller including digital-toanalog converters responsive to the more significant bits of the digital signal and operating in combination with multiplier and subtractor devices for establishing a coarse relationship between the analog and digital input signals and supplying an accurate reference voltage to a fine resolution digital-to-analog converter which is responsive to the less significant bits of the digital signal to produce fine data for summing with the coarse data and thereby form the output signal.

Trigonometric signal generator and machine control

Abstract: Digital and analog converter method and apparatus for generating trigonometrically related signals suitable for use with position measuring and position controlling systems. Two or more converter analog output signals are formed as a function of the digital input. The digital input generates a digital count difference between the counts in two digital counters. The two counters are both stepped by synchronously derived stepping pulses to produce counter output signals, exhibiting a phase difference proportional to the digital count difference. The counter output signals are logically combined to form analog output signals. Those analog output signals are pulse-width modulated rectangular waveforms which each include a fundamental sinusoidal frequency component having an amplitude proportional to a trigonometric function of the digital input. The analog output signals from the converter are typically connected as inputs to a position measuring device to trigonometrically define the position between two members of the position measuring device. The position measuring device is typically an transducer or other data element which responsively forms an analog output signal having a magnitude which indicates the relative position of the two members. The analog output signal is typically converted to a digital signal, in the form of a train of pulses, where each pulse represents an incremental distance. That digital signal, derived from the analog output signal, is typically supplied as an input to the converter which converts the digital input to the analog output, thereby forming a closed loop system.

Frequency domain analyzer using variable-rate time compression

Abstract: Contiguous frequency domain analysis of signals is achieved by sampling contiguous epochs of the signal; converting the sampled signal to a digital representation; storing the digital signal in a buffer; reading the stored digital signal a number of times at different reading rates to effect multiple frequency multiplications; converting the different digital signals red read analog equivalents; and passing the different analog signals through a fixed band-pass filter detector to effect an accelerated analysis of the frequency shifted signal.

Digital cathode-ray tube linearity corrector

Abstract: A system for correcting the signals transmitted to the deflection yokes of a cathode-ray tube employs digital means to produce an undistorted linear display while requiring a minimum of adjustments. Basically, the system utilizes digital circuitry to produce a correction factor from digital X- and Y-coordinate data supplied by a digital computer. This correction factor, which is equivalent to the sum of the squares of the X- and Y-coordinate data, is converted into an analog signal, along with the coordinate data, by digital to analog converters. The analog correction signal is multiplied by and then added to the analog coordinate signals, thereby producing the corrected deflection signals for an undistorted linear display on the essentially flat face of the tube. An analog correction signal may also be utilized to correct the focus of the electron beam on the tube face.

Fast high-precision analog digital converter for pulse spectrometry.

Abstract: Abstract An ADC with the following specifications has been designed and constructed: 8192 channels, amplitude range 0.05 to 10 V, positive, conversion time 12 μsec, max. integral linearity better than ± 2.5 × 10 −4 , stability of channel-width 0.5%. In a modification of the linear capacitor discharge a coarse and a fine measurement is executed subsequently, combined of a fast discharge and an interpolation with a slow discharge. The address oscillator works at 20 MHz, the address register is advanced during the coarse measurement in steps of 64 channels and during the fine measurement channel by channel. The discharge current generators are switched in exact synchronism with the pulses of the address oscillator; a two-step-synchronizing circuit is used. Special circuits have been developed for the pulsestretcher, the current-generators, current-switches and the discriminator. The high degree of stability and linearity is achieved through the proper use of field-effect-transistors, linear integrated circuits and fast digital intergrated circuits (emitter-coupled logic). Details of the tests performed and the testing methods are given.

A Class of Efficient High-Speed Digital Modems for Troposcatter Links

Abstract: A class of power and bandwidth efficient high-speed digital data modems is described and corresponding theoretical error rate performances presented as a function of signal-to-noise ratio for a range of typical links.

A Class of Signals for Analog Telemetry over a Coherent Channel

Abstract: This paper proposes and studies a class of signals which generalize frequency position modulation (FPM) and pulse position modulation (PPM). The generalization adds a degree of freedom analogous to a duty factor. Varying this quantity has an effect similar to that of varying the time-bandwidth occupancy in an FPM or PPM system, but it does not significantly increase the channel occupancy. The mean-square error is studied under large signal-to-noise ratio conditions and in the threshold region. We find that the additional degree of freedom allows us to trade between performance in these two ranges of signal-to-noise ratio. The nature of the signals, and their error behavior make them well suited to adaptive telemetry over a coherent channel. Small degrees of channel incoherence are considered and shown to produce only a small degradation in performance.

On delta modulation.

Abstract: The purpose of this thesis is to introduce Delta Modulation as an alternative to the more conventional carrier and pulse modulations, Chapter I briefly discusses the carrier and pulse modulations from the standpoint of signal - to - noise ratio, bandwidth occupancy and threshold effects. In this way, the merits of each is brought to the fore and the superiority of FM and PCM can he seen. Chapter II introduces Delta Modulation, a pulse code modulation, giving an extensive review of much of the more prominent literature on the subject. Aspects such as channel capacity, power, spectral densities, overloading, signal - to - noise ratio and bandwidth, are discussed. In Chapter III an experimental Delta-Sigma Modulation System is described in detail, from design to performance. Observations are made which correspond to some made in theory. The system transmits static signals and AC signals up to 20 HZ. The accuracy is good and the circuits simple. In Chapter IV suggestions are made to improve the systemis performance by simple means. Also mentioned are more elaborate means (Continuous Delta Modulation) which enhance the performance considerably but detract from the simplicity. Much of the literature quoted in the bibliography shows and discusses how delta modulation is simple in circuitry yet has all the advantages of PCM. It is upon this theme that the prototype Delta-Sigma Modulator is designed and built. All the circuits are kept as simple as possible. With integrated circuits, delta modulation is fast becoming an economical proposition. Delta modulation, though simple to implement, requires greater bandwidth than the conventional carrier modulations and PCM (for the same performance). At times this would make Delta Modulation uneconomical. However, there is a place for Delta Modulation alongside FM and PCM for some particular applications.