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United States Patent 1191 1111 4,445,028
Huber  Apr. 24, 1984  UNIDIRECIIONAL CODE FOR 1 INTERACTIVE MAP SYSTEM FOREIGN PATENT DOCUMENTS ' 55-82919 6/1980 Japan ................................. .. 235/462  Inventor: William A. Huber, Sea Glrt, NJ. 739575 5/1931) U_5_5_R_ 259/555 _ _ _ 744659 6/19,80 U.S.S.R. ....... .. 250/556  Asslgnw The Umttd States °f Alfltflcfl as 211305 3/1981 U.S.S.R. . 250/556 represented by the Secretary of the 1 2134711 3/1921 U.S.S.R. ............................ .. 250/556 A-rmy’ washmgton’ D'C' Primary Examiner—Harold I. Pitts  App1_ Na, 335,355 Assistant Examiner-—Robert LevAttorney, Agent, or Firm—Robert P. Gibson; Jeremiah  Filfidi J1ll1- 101 1982 G. Murray; Anne Vachon Dougherty  111¢.c1.3 ................................. .. .......... .. coax 7/10  ABSTRACT  U.S. Cl. ............................ 235/472; 235/462; A system for plotting information on 1-naps and reading _ 235/494 information therefrom comprising maps which have  Field of Search ............. .. 235/494, 456, 462, 495, n.,achine_readab1e codes on the backs thereof arranged 235/493’ 4631 470» 471’ 4723 250/555> 5561 5571 to indicate the coordinates of the map. A stylus is 558 adapted to be moved over the map surface to read the . map coordinates by sensing the codes thereon. The  References cued , novel unidirectional codes comprising code bars all U-$- PATENT DQCUMENTS extending in the same direction, permit the use of sim3,052,800 9/1962 Miller ................................ .. 250/556 Pllfied °°de Sensmg aPPa“"“S4,110,610 8/1978 Mueller et al. 4,143,267 3/1979 Johnson et al. ............... .. 250/231 R 8 Claims, 4 Drawing Figures
U S Patent Apr. 24, 1984 Sheet 1 of 2 4 445 028
UNIDIRECTIONAL CODE FOR INTERACTIVE
MAP SYSTEM The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalties thereon.
BACKGROUND OF THE INVENTION
The invention relates to a data transmission and recording system and more particularly to such a system designed to facilitate the exchange and recording of tactical military information between military units and to permit such information to be quickly and accurately plotted on maps. The system is interactive in that the information can flow in two directions, for example, from a higher echelon such as a command and control center to a field unit such as a company, using existing communications facilities; and other map information can be transmitted back to the command and control center using the same transmission facilities and the encoding apparatus of the present invention.
The system includes a processor module at the higher echelon which functions as an interface between the central processor of the higher-echelon’s computer and the communications system over which the map data is transmitted, and a field processor at the tactical-field unit which interfaces with the communications channel and the stylus. The stylus is a device which is moveable by hand over the surface of an encoded map to locate the coordinates thereon at which data is to be plotted and for transmitting back to the processor module map information relating to tactical operations. The data sent to higher echelons is stored for later use and can be applied to display type maps and can be re-transmitted to other field units, ifnecessary, using the system of the present invention. _
The incoming-map data can be temporarily stored in the field processor and plotted at the field operator’s convenience. The map data includes digitally coded map coordinates corresponding to the location on the map at which data is to be plotted. The maps are divided into a plurality of relatively large square map elements or mels and each mel is assigned a digital code according to its location along the x and y axes. The x and y coordinates of each mel are encoded on the back of the map in binary digital form, for example by printing two binary bar codes thereon in magnetic ink. The stylus includes a coordinate code sensor which can read the mel codes as the stylus is moved over the map surface. The stylus is electrically connected to the field processor and it includes a digital display of the desired map coordinates. When the stylus has been moved to a proper coordinate, the display for that coordinate will indicate that the proper coordinate has been reached, for example by blinking.
Since greater resolution is desired than is practical with a hand-operated stylus and the relatively large mels, each mel is further subdivided into a plurality of sub-mels, and the system is designed so that the operator locates the proper mel and one coordinate of one submel as described above by hand, and then the other coordinate of the proper sub-mel is located by means of a template and light emitting diode (LED) system attached to the stylus and electrically operated by several of the binary digits of lesser significance read out of the field processor. This two stage system permits high
resolution which would be otherwise impractical in a hand operated system.
The map coordinate sensors or transducers may take any one of numerous forms, however all comprise means to automatically sense the digital map mel codes and are capable of performing this function when moving across the map or when stationary. The underside of the stylus includes one or more magnets. The magnetic fields produced thereby are concentrated in the magnetic ink of the mel code bars to facilitate the reading thereof by the coordinate sensors.
The present invention is an improvement on a similar interactive map information exchange system and method described and claimed in a co-pending application by the present inventor, entitled INTERACTIVE MAP INFORMATION SYSTEM U.S. Pat. No. 4,420,682. The improvement of the present invention comprises the use of unidirectional map codes rather than the use of two orthogonal map codes to identify the x and y coordinates of each mel as well as one of the coordinates of the sub-mel. This unidirectional code simplifies somewhat the apparatus required and permits the plotting and reading of information over a larger area of the map.
The present invention provides for high accuracy, high resolution and high speed plotting and reading of information to and from maps by the use of a data reduction technique in which the digital code representing a map coordinate contains a sufficient number of bits, for example nine binary bits, to permit a resolution of 512 lines along each orthogonal map coordinate. This high resolution results in 262,144 square map elements which would be approximately 55 mils or 1/ 18 of an inch on a side for a typical map of 28><28 inches. Such a mel is too small to contain the required coordinate coding and also it would be difficult for an operator to locate the proper mel by manually moving a code sensor over such a coded map even if it could be coded to this resolution. To circumvent these difficulties, the present invention provides a system wherein the map is divided into much larger mels, for example, each of the x and y map axes may be divided into l6 equal parts. This results in 256 square mels. For the" 28 X 28 inch map mentioned, each of these mels is then almost 2 inches on a side. Since 16 is 24, four binary digits are necessary to specify each of the x and y coordinates of each such mel. These four binary digits as well as additional digits, as_explained below, are encoded in magnetic ink on the back of the maps to facilitate automatic reading thereof by the coordinate code sensor which is part of the manually operated stylus. The binary code may consist of magnetic ink bars printed on the back of the map within each mel. Two arrays of these code bars indicating the x and y coordinate of the mel are located within each mel.
Each mel is divided into a large number of sub mels to achieve the aforementioned 512 line resolution. For example, each of the 256 mels mentioned may be divided into 1024 sub mels. This means that each coordinate of each mel is sub-divided into 32 parts, requiring a five bit binary number to specify the location of each of the x and y sub mels. Thus a nine bit binary number is required to fully specify each of the x and y coordinates to be plotted or read.
Each mel includes a four bit x mel code and a four bit y mel code comprising vertically disposed bars which