US 4,039,784 A · Digital minimum/maximum vector CRT display

Abstract

A vector CRT display apparatus for faithfully reproducing an analog signal having high frequency components include an A-D converter, a digital minimum/maximum circuit and a recirculating shift register to derive from the signal, in successive sampling periods, two digital words representing, respectively, a minimum amplitude value date point and a maximum amplitude value data point of the signal. In each sampling period, the minimum/maximum circuit stores in the memory the most relevant of the minimum and maximum amplitude values and determine whether the remaining values should be held over to the next sampling period before it is stored, or can be discarded. As a result, if new minimum and new maximum amplitude values occur in the same sample period, one will be loaded into the memory and the other will be held over and loaded into the memory in the next sample period. By storing only the most relevant of the minimum and maximum amplitude values, the size of the memory required, and its cost are substantially reduced; additionally, the storage of only important values in the memory for later display contributes to a uniformity of brightness of the display.

Claims12

Dependent claims

The method of providing a faithful digital representation of the amplitude variations of an analog signal comprising deriving in each of successive sampling periods two digital words representative, respectively, of minimum and maximum values of said signal during such sampling period, determining which of said values is most relevant to faithful representation of said signal, storing said most relevant value and discarding the other of said when only one of the said values represent a new maximum and a new minimum value, and storing both of said values in the order derived when both represent new minimum and maximum values and, hence, are relevant values, storing in said sampling period the first value derived in storing the other value in the next successive sampling period, and reading out said stored values in the order in which they were stored.

Apparatus for producing a display of the variations in amplitude of a data signal with respect to a time base by deflecting an electron beam upon the screen of a cathode ray tube comprising:

first means having an input and an output, said input being connected to the source of the signal and operative to produce in said output in said successive periods two digital words representing, respectively, a minimum amplitude value data point and a maximum amplitude value data point of said signal in each of said periods,
recirculating memory means having an input connected to receive the digital words produced in the output of said first-mentioned means and arranged to store, in sequence, a predetermined number of said digital words produced in said successive periods, said memory means having an output and arranged cyclically to provide, in sequence, at said output all of said stored digital words, the first stored digital word being dropped off at the output and a new digital word being added at the input of said memory means from said first-mentioned means at the end of each cycle,
a digital to analog converter connected to the output of said memory means,
means synchronized with the outputting of digital words by said memory means after conversion by said digital to analog converter to produce in each of successive periods first vector component voltage increments acting on said electron beam in a predetermined direction and each increment having a magnitude determined by the difference between the minimum value data point and the maximum value data point of said signal, said last-mentioned means including means to produce second vector component voltage increments each having a substantially constant magnitude to deflect said electron beam in a direction substantially at a right angle with respect to said predetermined direction to represent said time base, whereby said electron beam is caused to move across the surface of said screen in accordance with the variations in amplitude with time of said signal.

1 more element

An apparatus for generating signals for reproducing an analog signal on a vector cathode ray tube display device comprising in combination:

(a) an analog to digital converter having input means and output means;
(b) means for coupling an analog input signal to the input of said analog to digital converter;
(c) means for establishing a series of contiguous sample periods;
(d) means coupled to the output of said analog to digital converter for comparing said output during one sample period with the maximum output achieved during the previous sample period;
(e) means coupled to the output of said analog to digital converter for comparing said output during one sample period with the minimum output achieved during the previous sample period;
(f) means responsive to said maximum and minimum comparison means for generating a first signal when only a new maximum is reached during said sample period and for generating a second signal when only a new minimum is reached during said sample period and for generating a third signal when a new maximum and a new minimum are both reached;
(g) means responsive to said first signal for generating a beam deflection signal for said cathode ray tube display device one component of which uses as a starting value the termination value of said vector component during the previous sample period and said stored maximum value when only a new maximum value is reached in the sample period;
(h) means responsive to said second signal for generating a beam deflection signal for said cathode ray tube display device one component of which uses as a starting value the termination value of said vector component during the previous sample period and said stored minimum value when only a new minimum value is reached in the sample period;
and
(i) means responsive to said third signal for generating a beam deflection signal for said cathode ray tube display device one component of which uses as a starting value the termination value of said vector component during the previous sample period and the first achieved maximum or minimum value during the sample period when a new maximum and a new minimum value are both achieved during the sample period.

7 more elements

Dependencies are inferred from the claim text.

Digital minimum/maximum vector CRT display

Life of this patent

Digital minimum/maximum vector CRT display

Life of this patent

Abstract

Claims12