DIGITAL SCAN CONVERTER

• US 3,810,174 A
• Filed: 11/28/1969
• Issued: 05/07/1974
• Est. Priority Date: 11/28/1969
• Status: Expired due to Term

• Current Assignee: Eugene W. Opittek, James L. Heard, William C. Hoffman
• Original Assignee: Eugene W. Opittek, James L. Heard, William C. Hoffman
• Inventors: Heard, James L., Hoffman, William C., Opittek, Eugene W.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US04/880,630
• Time in Patent Office: 1,621 Days
• Field of Search: 178/DIG.22,DIG.24 343/5DP,5SC
• US Class Current: 342/185
• CPC Class Codes: G01S 7/064 using a display memory for image processing G01S7/298 takes precedence
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G01S 7/298 Scan converters

Abstract

A digital system is disclosed for conversion of data rates inherent in various scanning patterns to different rates for display. A buffer memory is employed to accumulate blocks of data pertaining to successive scanning lines in a rectilinear or polar coordinate scanning pattern. The data is transferred in blocks to a bulk storage memory from which it is read cyclically for display. Different scanning and display patterns are accommodated through mode control switches. In multi-bar-elevation radar scanning modes, detection of targets is augmented by storing for simultaneous display a plurality of past frame histories or by storing an intensity value in binary code for a target return and decreasing it in uniform steps during successive scanning cycles during which a target return is not received from the same range element until it reaches a level of zero.

Claims

1. A digital scan converter comprising:

sensing means for producing discrete video signals as a field of view is cyclically scanned in a predetermined pattern of successive lines at one particular rate;

means for converting said video signals into elements of digital data, each element consisting of a binary number of k digits representative of the amplitude of a video signal where k is a constant integer;

buffer storage means for receiving said elements of digital data and for storing a block therein said elements of digital data pertaining to a given line as a binary number;

bulk storage means for receiving, from said buffer storage means in block form, said elements of digital data pertaining to said given line and for storing said data in a memory block preassigned to data pertaining to said gIven line;

means for reading out data from said bulk storage means in a predetermined order bearing some relation to the order in which associated lines of said field are scanned for repeated display of all lines of said pattern at a rate which differs from said one particular rate;

display means having an electron beam and a display surface responsive to said reading means for displaying said data by intensity modulating said beam in a frame with lines of displayed data spacially arranged relative to each other in the same sequence as scanned in said field;

temporary means adapted to receive from said converting means said binary numbers and to store said binary numbers in proper sequence as microwords until transferred therefrom; and

means for transferring said microwords to said block of said buffer storage means in groups, each group comprising a word, and said block consists of n words where n is a constant integer, and the product of the integers k and n is equal to the number of elements of digital data pertaining to a given line.

2. A digital scan converter as defined in claim 1 wherein said buffer storage means includes a number of blocks equal to less than the total number of lines scanned in said field of view during one scanning cycle, and sequencing means directing said words of successive lines scanned by said sensing means into successive ones of said blocks, and said blocks are selected to receive said words cyclically, said buffer storage means further comprising means for storing in association with each line block of n words an identifying number, where identifying numbers are assigned to lines scanned by said sensing means to correspond with addresses of memory blocks preassigned in said bulk storage means to respective line blocks of data, and said bulk storage means further comprises means responsive to said identifying number of a given line block of data for transferring out of said buffer memory said given line block of data stored therein into said bulk memory at a preassigned memory block.

3. A digital scan converter as defined in claim 2 wherein said display means is for the purpose of searching for targets in said field and said bulk storage means includes n memory blocks, where n is an arbitrary integer, in order to display n past histories for each line scanned, whereby said display means responds to said reading means to display n past frame histories with corresponding lines adjacent to each other for augmentation of target detection by display of a cluster of target indications for a true target video signal and display of random target indications for a false target video signal.

4. A digital scan converter as defined in claim 3 wherein said sensing means is adapted to search for targets in said field and said bulk storage means includes n memory cells for each digital data element of a line scanned, where n is an arbitrary integer specifying the number of binary digits of an intensity code stored for a given data element indicating a valid target sensed during the most recent scanning cycle, said intensity code calling for maximum intensity in said display means, wherein said bulk storage means includes means for altering the intensity code of a given stored data element in uniform stages each time the data element is updated following succeeding scanning cycles of said field by said sensing means and said sensing means produces no indication of a target, and wherein said display means includes means for providing a target indication in response to a given stored data element with an intensity specified by the intensity code thereof, whereby augmentation of target detection is provided by display of a trail of target indications with the most intense indication at the head thereof.

5. A digital scan converter comprising:

sensing means for producing discrete video signals as a field of view is cyclically scanned in a predetermined pAttern of successive lines at one particular rate, said predetermined scanning pattern having an arbitrary number of lines;

means for converting said video signals into elements of digital data, each element consisting of a binary number of k digits representative of the amplitude of a video signal where k is a constant integer;

buffer storage means for receiving said elements of digital data and for storing in a block therein said elements of digital data pertaining to a given line as a binary number;

said buffer storage means including a predetermined number of memory blocks, said predetermined number being less than said arbitrary number, sequencing means for storing successive line blocks of data in different memory blocks, and means for storing for each line block of data a unique number associated therewith, said number corresponding to the address of a preassigned memory block in said bulk storage means;

bulk storage means for receiving from said buffer storage means in block form, said elements of digital data pertaining to said given line and for storing said data in a memory block preassigned to data pertaining to said given line;

said bulk storage means including means for cyclically addressing memory blocks therein in a predetermined order, means for comparing the address of each memory block with unique numbers stored in said buffer storage means, and means responsive to said comparing means for transferring a line block of data from said buffer storage means into a memory block in said bulk storage means having an address that is the same as the unique number associated therewith and stored in said buffer storage means;

means for reading out data from said bulk storage means in a predetermined order bearing some relation to the order in which associated lines of said field are scanned for repeated display of all lines of said pattern at a rate which differs from said one particular rate; and

display means having an electron beam and a display surface responsive to said reading means for displaying said data by intensity modulating said beam in a frame with lines of displayed data spacially arranged relative to each other in the same sequence as scanned in said field.

6. A digital scan converter comprising:

sensing means for producing discrete video signals at one particular rate as a field of view is repeatedly scanned back and forth in a predetermined pattern of successive lines, said lines being arbitrarily numbered in sequence from one side of said field to the other;

means for converting said video signals into elements of digital data;

bulk storage means for storing blocks of digital data, each block pertaining to a given line of said field being assigned to a memory location having an address number which corresponds to the number of said given line in said field;

means for cyclically reading out line blocks of data from memory locations in said bulk storage means;

display means responsive to said reading means for displaying said line blocks of data in a frame with lines of displayed data spacially arranged relative to each other in the same manner as the corresponding lines in said field;

buffer storage means for receiving said elements of digital data and for storing in blocks therein line blocks of data, each line block of data being stored therein until said reading means address a memory location to which assigned; and

means for transferring from said buffer storage means to said bulk storage means a block of line data when a memory area to which assigned is addressed by said reading means.

7. A digital scan converter as defined in claim 6 wherein said buffer storage means includes means for storing for each line block of data a number assigned to the scanning line from which derived, and said transferring means includes means for comparing the addresses of memory locations as they are read with line numbers stored in said buffer storage means.

8. A digital scan converter As defined in claim 7 wherein said means for storing line numbers comprises a number of discrete registers, each adapted to store the line number of a line block of data stored in said buffer storage means, and wherein said buffer storage means comprises a number of blocks of memory corresponding to said number of discrete registers, each register being associated with a block of memory in said buffer storage means to identify the block of memory from which a line block of data is to be transferred to said bulk storage means in response to said transferring means.

9. A digital scan converter as defined in claim 8 including:

means for cyclically selecting said discrete registers in response to said sensing means, a succeeding one being selected at the start of each line scan; and

means responsive to said cyclical selecting means for addressing said buffer storage means to store in an associated block of memory a line block of data derived from a line being scanned.

10. A digital scan converter as defined in claim 8 wherein said comparing means comprises a plurality of comparators, one for each discrete register adapted to compare the address of a given memory area to be read next by said reading means with the contents thereof and, in response to a comparison therewith, causing said transferring means to transfer a line block of data from the associated block of memory in said buffer storage means to said given memory location.

11. A digital scan converter comprising:

sensing means for producing video signals at a particular rate as a field of view is scanned in a predetermined pattern of successive lines;

means for converting said video signals into elements of digital data including means for averaging n successive video returns into one element of digital data where n is an arbitrary integer;

means controlling said sensing means to produce n times as many video signals for a given line scanned as are converted into elements of digital data means for receiving said elements of digital data in sequence and for storing said data received for retrieval in a predetermined order related to the order in which the corresponding line of said field was scanned;

means for cyclically reading out line blocks of data from said means for storing in said predetermined order; and

display means responsive to said reading means for displaying said line blocks of data in a frame at a rate independent of said particular rate with lines of displayed data spacially arranged relative to each other in the same sequence as scanned in said field.

12. A digital scan converter comprising:

sensing means for producing discrete video signals as a line of view is repeatedly scanned at one particular rate, where said sensing means is being transported in a direction substantially at right angle to said line of view to scan a passing scene;

means for converting said video signals into quantized elements of digital data, each element consisting of a binary number of k digits representative of the amplitude of a video signal, where k is a constant integer;

means adapted to receive from said converting means said binary numbers and to store said binary numbers in proper sequence as microwords until transferred therefrom;

means for transferring said microwords to said block of storage means in groups, each group comprising a word, and said block consists of n words, where n is a constant integer, and the product of the integers k and n is equal to the number of elements of digital data pertaining to a given line;

storage means for receiving said elements of digital data and for storing data from a given line in a memory block preassigned to one of a given number of memory locations;

means for reading out line blocks of data from said means in a predetermined order bearing some relation to the order in which stored for repeated display of all lines of data stored in said given number of memory locations at a rate which differs from said one particular rate such that all lines are displayed in one frame for viewing in a spacial relationship corresponding to lines of view scanned to obtain corresponding line blocks of data with the line block of data of the most recently scanned line of view read for display first during each frame display cycle, and stored line blocks of data of all other scanned lines of view read for display with data of the more recently scanned line read next in sequence; and

display means responsive to said means for reading out for displaying said line blocks of data in a frame.

13. A digital scan converter as defined in claim 12 wherein said storage means further includes a buffer storage means and a bulk storage means, said buffer storage means comprising a number of blocks equal to less than the total number of lines stored in said bulk storage means for display in one frame, sequencing means directing said words of successive lines scanned by said sensing means into sccessive ones of said blocks, said blocks being selected to receive said words cyclically, said buffer storage means further comprising means for storing in association with each line block of n words an identifying number, where identifying numbers are assigned to lines scanned by said sensing means to correspond with addresses of memory blocks preassigned in said bulk storage means to respective line blocks of data, and said bulk storage means comprises means for reading out of said buffer storage means a given line block of data stored therein for transfer to said bulk storage means when the address of a memory block to be read out of said bulk storage means to said display means compares with an identifying number stored in said buffer storage means associated with said given line block of data.

14. A digital scan converter as defined in claim 13 wherein said identifying number is assigned to each line block of data by a counter driven by a signal source having a frequency proportional to the velocity at which said scanning means is viewing a passing scene.

15. A digital scan converter as defined in claim 14 wherein said sensing means is operated to produce n times as many video signals for a given line scanned as are converted into elements of digital data, where n is an arbitrary integer, and said means for converting said video signals into elements of digital data includes means for averaging n successive video returns into one element of digital data.

16. A digital scan converter as defined in claim 15 wherein said sensing means is operated to scan m times as many lines as are to be stored in said bulk storage means for display, where m is an arbitrary integer, and said buffer storage means includes means for averaging m successive lines by averaging corresponding elements of said m lines.

17. A digital scan converter comprising:

sensing means for producing discrete video signals as a field of view is cyclically scanned in a predetermined pattern of successive planes at one particular rate, each plane comprising a predetermined number of scanned lines;

means for converting said video signals into elements of digital data;

buffer storage means having a plurality of memory blocks for receiving said elements of digital data and for storing each line block of data in a block therein said elements of digital data pertaining to a given line of a given plane;

bulk storage means for receiving, from said buffer storage means in block form, said elements of digital data pertaining to said given line of said given plane, and for storing said data in each line block of data in a memory block, each memory block being preassigned to data pertaining to a given line of said given plane;

means for reading out line blocks of data from said bulk storage means in a predetermined order bearing some relation to the order in which associated lines of said given plane are scanned with coRresponding lines of all other planes interlaced with lines of said given plane, for repeated display of all lines of selected planes of said pattern at a rate which differs from said one particular rate;

means for selecting planes of said pattern for display; and

display means responsive to said selecting means for displaying line blocks of data from selected planes in a frame with lines of displayed data from a given plane spacially arranged relative to each other in the same sequence as scanned in said field.

18. A digital scan converter as defined by claim 17 wherein said selecting means is adapted to select all planes for simultaneous display in order to monitor the entire field, and to select one plane in order to concentrate on video signals stored for display from just one plane.

19. A digital scan converter as defined by claim 18 wherein said bulk storage means includes n memory blocks for each plane, where n is an arbitrary integer, in order to display n past histories for each line, whereby said display means responds to said reading means to display n past frame histories with corresponding lines adjacent to each other for augmentation of target detection by display of a cluster of target indications for a true target video signal and display of random target indications for a false target video signal.

20. A digital scan converter as defined in claim 18 wherein said storage means includes n memory cells for each digital data element of a line scanned in a given plane, where n is an arbitrary integer specifying the number of binary digits of an intensity code stored for a given data element indicating a valid target sensed during the most recent scanning cycle of said pattern, said intensity code calling for maximum intensity in said display means, and wherein said storage means includes means for altering the intensity code of a given stored data element in uniform stages each time the data element is updated following succeeding scanning cycles of said pattern by said sensing means and said sensing means produces no indication of a target, and wherein said display means includes means for providing a target indication in response to a given stored data element with an intensity specified by the intensity code thereof, whereby augmentation of target detection is provided by display of a trail of target indications with the most intense indication at the head thereof.

21. A digital scan converter comprising:

sensing means for producing discrete video signals as a field of view is cyclically scanned in a predetermined pattern of successive lines;

means for converting said video signals into elements of digital data, each element representing at least one video signal of at least one line;

m memory blocks, for storing said elements of digital data, one for each of said lines scanned by said sensing means, and said blocks are assigned m successive address numbers, each of said blocks comprising n memory locations, one memory location for each of said elements of digital data, and said locations are assigned n successive address numbers;

means for addressing successive locations of a given block by a composite address of m and n binary digits, where the binary value of said n binary digits is incremented by for each element to be stored;

means for altering the value of said m binary digits by one as the scanning of the next line is initiated by said sensing means as said lines are continuously scanned by said sensing means;

means for reading out data from said memory blocks in a predetermined order for repeated display of all lines of said pattern by reading out corresponding elements of digital data from all lines in repeated sequences, each sequence starting with one line at one side of said pattern and concluding with one line at a side opposite said one side of said pattern; and

display means responsive to said reading means for displaying sAid data in a frame with lines of displayed data spacially arranged relative to each other in the same sequence as scanned in said field, and orthogonally positioned relative to the direction in which a sequence of corresponding elements are displayed as read out of said storage means by said reading means.

22. A digital scan converter as defined in claim 21 wherein said means for reading out data from said memory blocks comprises:

a source of a signal alternating at a substantially constant frequency; and

first and second counting means driven in cascade by said signal, said first counting means providing m address digits of a composite address, and said second counting means providing n address digits of said composite address, where m and n digits have the same address connotations as in said storage means.

23. A digital scan converter as defined in claim 22 wherein said second counting means comprises a first binary counter having n-k stages and a second binary counter having k stages connected in cascade with said first binary counter but arranged to provide the least significant k digits of said n address digits, whereby all elements of all lines are read for display in 2k interlaced fields of 2n k lines per field.

24. A digital scan converter as defined in claim 23 wherein k is equal to 1.

25. In a data display system, the combination comprising:

sensing means for producing discrete video signals as a field of view is cyclically scanned in a predetermined pattern of successive lines;

means connected to receive said discrete video signals and for threshold detecting the amplitude of each discrete video signal for determining the presence of a target, thereby producing a succession of detector output signals as said sensing means scans, one detector output signal for each video signal in as said sensing means scans a given line;

means for encoding each detector output signal indicating the presence of a target as a number of predetermined maximum value, and for storing the resulting maximum value code as datum of the most recent scanning cycle;

means for altering the value code of each datum stored during successive scanning cycles to lower the numerical values thereof in equal increments when corresponding detector output signals do not indicate the presence of a target until a predetermined minimum value is reached; and

means for displaying data stored with lines of displayed data spatially arranged relative to each other in the same sequence as scanned by said scanning means, each datum being displayed with an intensity proportional to its current value code, whereby display of a moving target is augmented by having a datum representing a target from the most recent scanning cycle displayed with maximum intensity followed by a trail of displayed data, each datum of said trail being of successively less intensity in a direction away from the datum of maximum intensity.

26. In a digital scan converter adapted to receive a field of data elements, said elements representing quantized video signals received from a sensor in sequence as said sensor scans a field of view in substantially parallel lines, and adapted to transmit said field of data elements to a utilization device, the combination comprising:

means for grouping a predetermined number of said elements into line blocks of data, one line block for each of said parallel lines scanned; and

means for averaging a predetermined number of successive line blocks of data grouped for transmittal to said utilization device, whereby fewer lines of data are transmitted to said utilization device than are received by said scan converter.

27. In a digital scan converter adapted to receive a field of data elements, said elements representing quantized video signals recieved form a sensor in sequence as said sensor scans a field of view in substantially parallel lines, and adapTed to transmit said field of data elements to a utilization device, the combination comprising:

means for averaging a predetermined number of successive elements of data into new elements; and

means for grouping a predetermined number of said new elements into line blocks of data, one line block for each of said parallel lines scanned, whereby fewer elements of data are transmitted to said utilization device for each line block of data than are received by said scan converter.

28. In a digital scan converter as defined in claim 27 including means for averaging a predetermined number of successive line blocks of data grouped for transmittal to said utilization device, whereby fewer lines of data are transmitted to said utilization device than are received by said scan converter.