Showing papers on "Effective number of bits published in 1970"

Pulse-width frequency modulation device

Abstract: As described herein, a train of pulses used to control a servo-motor is modulated in accordance with the values of a varying digital input signal. To obtain accuracy of control, the digital input signal is divided into two components; a first group of bits representing integer order values; and a second group of bits representing fractional order data. A modulating circuit responds to the integer order bits to width modulate the pulse train in accordance with the magnitude represented by the integer order bits. The fractional order data bits are accumulated until the sum thereof at least equals the value of the least significant bit of the integer order component. At this time, the sum signal is added to the integer order data to add an increment of width modulation to the pulse then being modulated.

Apparatus including delay means for detecting the absence of information in a stream of bits

Abstract: Herein is revealed a missing information bit detector which is utilized in reading either double frequency or phase encoded information. A first circuit receives the information stream of clock and data bits and generates a series of pulses whose width is dependent on the delay of the first circuit, the time between successive bits and the duration of such bits received at its input. A low pass digital filter is coupled to receive such pulses and generates an output signal indicative of a missing bit when the width of such pulses in greater than a specified value. Also revealed is a means for separating the clock and data bits while maintaining a selected phase relationship therebetween.

Simple Data Compression by Redundancy Replacement

Abstract: : A redundacny replacement system is described. Whenever m bits of an n-bit word are identical with corresponding bits in the preceding word, these bits are replaced by m bits from a second source. An extra bit is added to each word to signal the substitution. If words with m redundant bits occur with probability P(m), one gains an extra channel of average capacity mP(m) - 1. The system is analyzed as a data compressor that enhances the source entropy by replacing redundancies. An effective data compression of 2.11 is obtained for typical voice sources. (Author)