Signal correction system

Claim 2

A signal processing system wherein an input signal S(w) contains an error component e(w) and a signal component s(w) comprising: a summer, said input signal being applied to said summer; a digital memory storing digital words representing the pattern of said error component e(w); a digital-to-analog converter, said digital words being applied to said digital-to-analog converter to produce an analog error signal e(w), said error signal being applied to said summer to produce an approximation S''(w) of said signal component; an analog-to-digital converter, the output of said summer being applied to said analog-to-digital converter; and digital logic circuitry operable during intervals of time when said signal component is zero to load digital words from said analog-to-digital converter, said digital words representing the pattern of said error signal, said digital words being loaded into said digital memory to update the contents of said memory thereby providing a new error correction e(w).

Claim 3

In a system producing stored digital words representing the optical characteristics of an optical image of the type including a scanning detector for sequentially scanning said optical image in a raster of scan lines to produce an analog electrical signal representing said optical image along said scan lines and an analog-to-digital converter responsive to a timing pulse input for producing a digital word representing the magnitude of said analog signal at the occurrence of each timing pulse, a system for correcting said analog electrical signal for shading of said optical image comprising: a summer, said analog electrical signal being applied to said summer; a digital memory storing digital words representing the pattern of said shading; a digital-to-analog converter, said digital words from said memory being applied to said digital-to-analog converter to produce an error signal representing said shading, said error signal being applied to said summer to produce an output of said summer representing the video signal without shading, the output of said summer being applied to said analog-to-digital converter; and means operable during intervals in which said analog signal represents only shading to load said memory with digital words representing the pattern of said shading.

Claim 4

In a system producing stored digital words representing the optical characteristics of an optical image of the type including a scanning detector for sequentially scanning said optical image in a raster of scan lines to produce an analog electrical signal representing said optical image along said scan lines and an analog-to-digital converter responsive to a timing pulse input for producing a digital word representing the magnitude of said analog signal at the occurrence of each timing pulse, a system for correcting said analog electrical signal for shading of said optical image comprising: a summer, said analog electrical signal being applied to said summer; a digital memory storing digital words representing the pattern of said shading; a digital-to-analog converter, said digital words from said memory being applied to said digital-to-analog converter to produce an error signal representing said shading, said error signal being applied to said summer to produce an output of said summer representing the video signal without shading, the output of said summer being applied to said analog-to-digital converter; and means operable during intervals in which said analog signal represents only shading to load said memory with digital words representing the pattern of said shading.

Claim 5

The system recited in claim 2 wherein said means operable during intervals in which said analog signal represents only shading comprises: a switch connected to said digital memory to switch said digital memory between a load mode of operation and a read mode of operation.

Claim 6

The system recited in claim 3 wherein said means further comprises: an analog-to-digital converter, the output of said summer being applied to said analog-to-digital converter, the analog-to-digital converter being connected to said memory to store digital words representing the pattern of said shading when said memory is in the load mode of operation.

Claim 7

The system recited in claim 4 further comprising: a source of clock pulses, and counting means, said clock pulses being applied thereto to produce as outputs from said counting means address signals controlling said digital memory to store digital words in particular addresses therein.

Claim 8

The system recited in claim 5 wherein the output of one stage of said counting means is applied to said analog-to-digital converter to control the time at which the analog signal applied thereto is digitized.

Claim 9

The system recited in claim 6 wherein said scanning detector is a television type camera and wherein the outputs of stages of said counting means are applied to the horizontal synchronizing input and the vertical synchronizing input of said television type camera to synchronize the video television image with the storage of digital signals in said memory.