WO2002006763A1

WO2002006763A1 - Apparatus and method for determining a grid reference

Info

Publication number: WO2002006763A1
Application number: PCT/AU2001/000848
Authority: WO
Inventors: Andrew John Dahl; Alan John Victor
Original assignee: Andrew John Dahl; Alan John Victor
Priority date: 2000-07-13
Filing date: 2001-07-13
Publication date: 2002-01-24
Also published as: AUPQ876600A0

Abstract

An apparatus for determining an eight figure grid reference comprising an eight figure roamer (10) having a first square (11) divided into ten equal horizontal segments by a series of equally spaced horizontal lines (13) and having ten equally spaced index lines (15) sloping up the square (11) at approximately 84 degrees from the horizontal and an adjacent second square (12) divided into ten equal vertical segments by a series of equally spaced vertical lines (14) and having ten equally spaced index lines (16) sloping across the square (12) at an angle of approximately 6 degrees below the horizontal. A method of using the roamer (10) is also described.

Description

TITLE

"APPARATUS AND METHOD FOR DETERMINING

A GRID REFERENCE"

FIELD OF THE INVENTION THIS INVENTION relates to a method of determining an eight figure grid reference and an apparatus for working the method.

BACKGROUND

People involved in orienteering and the military are familiar with the need to determine the grid reference of a location by using a protractor and a map. Military personnel will be familiar with the military service protractor. The service protractor is semi circular with angles between zero and 3200 mils inscribed around the curved perimeter. Featured on the body of the service protractor are various scales and six figure roamers. The six figure roamers are used for determining a grid reference with a six figure accuracy.

To obtain a more accurate grid reference it is necessary to interpolate between six figure grid references. Although adequate for most purposes this is not sufficiently accurate for military purposes, particularly when calling fire. When calling machine gun fire, artillery fire or mortar fire it is desirable to determine a grid reference with 8 figure accuracy. It is known to provide an 8 figure roamer for this purpose. However, the current 8 figure roamer is only available in one map scale, only allows for measuring grid references in one direction at any one time and cannot be used for plotting a grid reference. An improved method of determining an 8 figure grid reference and an apparatus for working the method is required. DISCLOSURE OF THE INVENTION In one form, although it need not be the only or indeed the broadest form, the invention resides in a method of determining an eight figure grid reference including the steps of: positioning an index mark of an eight figure plotting protractor over a point to be measured; reading a two figure grid reference from an easting of a grid square containing the point to be measured; reading across a six figure easting of the plotting protractor to read a third digit corresponding to an index line crossing said easting at a first intersection; reading across from said first intersection to determine a fourth digit thereby forming a four digit easting; reading a two figure grid reference from a northing of the grid square containing the point to be measured; reading down from a six figure northing of the plotting protractor to read a third digit corresponding to an index line crossing said northing at a second intersection. reading down from said second intersection to determine a fourth digit thereby forming a four digit northing; and combining said four digit easting and said four digit northing to produce an eight figure grid reference.

In a further aspect, the invention resides in a method of plotting an eight figure roamer comprising the steps of: locating an index mark over a four digit reference; moving the roamer to the right parallel to northing lines to locate a three digit easting reference; moving the roamer upwards parallel to easting lines to locate a three digit northing reference; moving the roamer to the right parallel to northing lines until an index line originating at the third easting digit intersects the easting line of reference at an intersection aligning with a scale digit equal to the fourth easting digit; ,-^• moving the roamer upwards parallel to easting lines until an index line originating in alignment with the third northing reference intersects the northing line of reference at an intersection aligning with a scale digit equal to the fourth northing digit; plotting the position of the index mark.

In yet a further aspect, the invention resides in an apparatus for determining an eight figure grid reference using an eight figure roamer comprising: a first square divided into ten equal horizontal segments and having ten equally spaced index lines sloping across said square at an angle of approximately 84 degrees above the horizontal; and a second square adjacent said first square and divided into ten equal vertical segments and having ten equally spaced index lines sloping across said square at an angle of approximately six degrees below the horizontal; wherein said first square and said second square are of the size of a grid square on a map.

Preferably, the index lines sloping at an angle of approximately 84 degrees slope at an angle of 84.29 degrees. More precisely the angle is 84.2894 degrees. The angle is specifically 84.2894068625 degrees.

Preferably, index lines sloping at an angle of approximately 6 degrees slope at an angle of 5.71 degrees. More precisely the angle is 5.7106 degrees. The angle is specifically 5.7105931375 degrees.

BRIEF DETAILS OF THE INVENTION In order to assist with understanding the invention it is described below with reference to the following figures in which: FIG. 1 shows the parts of an eight figure roamer; FIG. 2 shows the method of using the eight figure roamer of

FIG. 1 to determine an eight figure grid reference;

FIG. 3 shows a protractor incorporating an eight figure roamer for a 1 in 25,000 scale map and an eight figure roamer for a 1 in 50,000 scale map. FIGS. 4 to 6 show a method of plotting an eight figure grid reference using the eihgt figure roamer of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG 1 there is shown an eight figure roamer 10 consisting of two adjacent squares. Each square 11 , 12 is the size of a grid reference for a map being used and are of the appropriate scale. The left hand square 11 is divided into ten equal horizontal segments by a series of equally spaced parallel horizontal lines, such as 13. Similarly, the right hand square 12 is divided vertically in the same manner by a series of equally spaced parallel vertical lines, such as 14. Each square has a series of equally spaced parallel index lines sloping across the square. In the case of the left hand square 11 , the index lines, such as 15, slope from top to bottom slanted to the left, whereas in the right hand square 12, the index lines, such as 16, slope from left to right slanted to the bottom.

At the top centre where the squares 11 , 12 join, there is an index mark 17 which is placed over a point to be measured. Suitably this index mark is a hole of an appropriate size to be positioned over a point to be determined to eight figure grid reference accuracy. The index mark may be used for plotting or measuring a reference.

Along the top of the left hand square 11 there are digits 18 for determining a six figure easting. Across the bottom of the right hand square 12 there are digits 19 for determining an eight figure northing. At the far left hand side of the left hand square 11 are a series of digits 20 that are used for determining both the six figure northings and the eight figure eastings.

Each of the index lines 15 traverse a horizontal distance equal to the space between adjacent digits 18 along the top of the left hand square 11. Likewise, each of the index lines 16 traverse a vertical distance equal to the space between adjacent digits 20 on the left hand side of left square 1. The method of using the eight figure roamer is best described with reference to FIG.2. First, the index mark 17 is positioned over the point 21 to be measured on a map. The easting 22 of the grid square containing the point to be measured is read as the first two digits of the eight figure grid reference. The sloping index line 23 that crosses the identified easting 22 is found and followed to the top of the right hand box to identify the third digit 24 of the eight figure grid reference. The point 25 where the sloping line crosses the easting, ie. the first intersection, is then followed across to the left hand edge of the box to identify the fourth digit 26. This has now identified a four digit easting which, in the present case, is 3245. The two digit northing 27 of the grid square containing the point to be measured is then read from the map without moving the roamer. The left hand edge 28 of the right hand box 12 is followed down to the start of the index line 29 that crosses the northing 27. The identified start of the sloping line is then followed across the page to the left to identify the third digit 30 of the northing, in this case 4. The point 31 at which the sloping line crosses the northing of the second intersection is read down the page to identify the fourth digit 32 of the northing, in this case 3. This now completes the four digit northing which in this example is 5543.

The four digit easting and the four digit northing are combined to form an eight figure grid reference. In the example the grid reference is 3245 5543.

The eight figure roamer can be incorporated into existing service protractors. However, the inventor finds it more convenient to include the eight figure roamer in an eight figure plotting protractor 33 shown in FIG. 3. The protractor has a full scale 34 from 0 to 6400 mils etched around the outer perimeter. Within the perimeter is provided another scale 35 from 0 to 360 degrees. An eight figure roamer 36 is positioned at the side of the protractor for a first scale which in this case is 1 :25,000. A further eight figure roamer 37 is provided _^at another appropriate location such as one quadrant of the protractor at a different desired scale which in this case is 1 :50,000. The remaining space is printed with a range template 38.

The inventor has found that the eight figure plotting protractor with the eight figure roamer are useful in determining eight figure grid references on topographic survey maps and similar maps.

In FIG. 4, a starting procedure is shown to plot an eight figure grid reference using a roamer of the present invention. In this case the reference to be plotted is 3245 5543. The first step involves first locating a four digit reference. Index mark 17 is located over grid easting 32 and grid northing 55 to give location 3245, indicated as 39.

Referring to FIG. 5, a six digit grid reference is obtained by first moving roamer 10 and therefore index mark 17 to the right to the third digit for the easting, namely 4, indicated by 40, which is measured by the digits 18 on the top left hand scale of the roamer. Roamer 10 and index mark 17 are then moved up to give the third digit of the northing, namely 4, indicated by 41 , as measured by the digits 20 on the left hand scale of the roamer. The parallel grid lines 13, 14 are used to keep movement of the roamer parallel to the northing and easting lines on the reference map being used. Clearly, it does not matter whether the upwards movement or sideways movement is carried out first, as either approach will locate the index mark 17 at the desired six digit reference, which in this case is 324 554.

Finally, in FIG. 6, an eight digit reference is plotted. The roamer 10 is moved right until a left hand index line 48 originating at the third easting digit 40 intersects the easting 47 of the grid reference at an intersection 42 which aligns with a digit 43 on the left hand scale 20 corresponding with the fourth digit of the desired easting, in this case 5.

The roamer 10 is then moved up until a right hand index line

49 intersects the northing 44 of the grid reference at an intersection 45 which aligns with a digit 46 of the digits 19 at the bottom of the right hand square

12 corresponding with the fourth digit of the desired northing, in this case 3.

The index mark 17 is now located over grid reference 3245

5543 and may be marked by any suitable means.

Throughout the specification, the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

Claims

1. A method of determining an eight figure grid reference including the steps of: positioning an index mark of an eight figure plotting protractor over a point to be measured; reading a two figure grid reference from an easting of a grid square containing the point to be measured; reading across a six figure easting of the plotting protractor to read a third digit corresponding to an index line crossing said easting at a first intersection; reading across from said first intersection to determine a fourth digit thereby forming a four digit easting; reading a two figure grid reference from a northing of the grid square containing the point to be measured; reading down from a six figure northing of the plotting protractor to read a third digit corresponding to an index line crossing said northing at a second intersection; reading down from said second intersection to determine a fourth digit thereby forming a four digit northing; and combining said four digit easting and said four digit northing to produce an eight figure grid reference.

2. A method of plotting an eight figure roamer comprising the steps of: locating an index mark over a four digit reference; moving the roamer to the right parallel to northing lines to locate a three digit easting reference; moving the roamer upwards parallel to easting lines to locate a three digit northing reference; moving the roamer to the right parallel to northing lines until an index line originating at the third easting digit intersects the easting line of reference at an intersection aligning with a scale digit equal to the fourth easting digit; moving the roamer upwards parallel to easting lines until an index line originating in alignment with the third northing reference intersects the northing line of reference at an intersection aligning with a scale digit equal to the fourth northing digit; plotting the position of the index mark.

3. An apparatus for determining an eight figure grid reference using an eight figure roamer comprising: a first square divided into ten equal horizontal segments and having ten equally spaced index lines sloping across said square at an angle of approximately 84 degrees above the horizontal; and a second square adjacent said first square and divided into ten equal vertical segments and having ten equally spaced index lines sloping across said square at an angle of approximately six degrees below the horizontal; wherein said first square and said second square are of the size of a grid square on a map.

4. The apparatus of claim 3 wherein the ten equally spaced index lines of said first square slope at an angle of approximately 84.29 degrees.

5. The apparatus of claim 4 wherein the angle is specifically 84.2894 degrees.

6. The apparatus of claim 4 wherein the angle is precisely 84.2894068625 degrees.

7. The apparatus of claim 3 wherein the ten equally spaced index lines of said second square slope at angle of approximately 5.71 degrees.

8. The apparatus of claim 7 wherein the angle is specifically 5.7106 degrees.

9. The apparatus of claim 7 wherein the angle is precisely 5.7105931375 degrees.