Seismic playback system

Claim 1

In a system wherein each analog signal, among a wide dynamic amplitude range of analog signals, is represented by a corresponding digital word in the form of digital signals representing the algebraic equation of ein + OR - AG E wherein ein represents the amplitude of a particular analog signal in said range, A represents a mantissa, G represents a radix of the number system used, and E represents an exponent, and wherein some of said digital signals represent A and some represent E, the method of making, from said digital signals, an analog signal eout suitable for making a visible display, comprising: transferring the digital signals representing A to a digital-toanalog converter; transferring the digital signals representing each exponent E to a decoder unit to develop a voltage representative of said exponent; transferring said voltage representative of said exponent E developed by said decoder unit to means including weighting and integrating networks for developing a voltage level representing GEave according to the average seismic record energy decay; generating an analog reference voltage Vref from the last mentioned voltage level, wherein Vref GEave; applying said reference voltage Vref to said digital-to-analog converter to develop an analog output voltage eout which is a function of Vref and the mantissa A; processing said analog output voltage eout to develop a signal voltage Vplayback; and visIbly displaying said signal voltage Vplayback.

Claim 10

A method of making minimally distorted compressed dynamic amplitude range analog signals, suitable for making oscillograms from wide dynamic amplitude range analog signals, comprising: a. converting each said wide dynamic amplitude range analog signal to a plurality of digital signals representing a digital word, said digital word, in turn, representing the mathematical relationship ein + or - AG E wherein ein represents the amplitude of each said wide dynamic amplitude range analog signal, A represents a mantissa, G is a constant and represents a radix of the number system employed, E represents an exponent, and wherein some of said digital signals of said digital word represent A and other represent E; b. storing said digital signals representing A and E; c. decoding the stored digital signals representing E and providing a first analog signal representative of Eave wherein Eave represents the average value of E, including the energy decay thereof; d. generating, by weighting and integrating, a second analog signal Vref defined by the mathematical relationship Vref (GEave/B) wherein B represents a compression factor; e. converting the stored digital signals representing A to a third analog signal VD-A representative of A; and f. combining said second and third analog signals to provide a fourth analog signal Vplayback defined by the relationship Vplayback (F+A)((G/B) EVref wherein F is a translation factor.

Claim 11

A method of making minimally distorted compressed dynamic amplitude range analog signals, suitable for making oscillograms from wide dynamic amplitude range analog signals, comprising: a. converting each said wide dynamic amplitude range analog signal to a plurality of digital signals representing a digital word, said digital word, in turn, representing the mathematical relationship ein + or - AG E wherein ein represents the amplitude of each said wide dynamic amplitude range analog signal, A represents a mantissa, G is a constant and represents a radix of the number system employed, E represents an exponent, and wherein some of said digital signals of said digital word represent A and other represent E; b. storing said digital signals representing A and E; c. decoding the stored digital signals representing E and providing a first analog signal representative of Eave wherein Eave represents the average value of E, including the energy decay thereof; d. generating, by weighting and integrating, a second analog signal Vref defined by the mathematical relationship Vref (GEave/B) wherein B represents a compression factor; e. converting the stored digital signals representing A to a third analog signal VD-A representative of A; and f. combining said second and third analog signals to provide a fourth analog signal Vplayback defined by the relationship Vplayback (F+A)((G/B) EVref wherein F is a translation factor.