A New Hand-held Calculator for Surveying, Mapping and Geomatics

by Purnell, Jon B

ABSTRACT:

Even though students have access to a dedicated computer lab equipped with CAD, least squares, GPS, and coordinate geometry and mapping software, hand-held calculators continue to play a central role in the Surveying-Geomatics program at Peninsula College. For many years, Hewlett-Packard's HP-48 series calculators were used at the college and throughout the surveying and allied disciplines, but when HP-48s became scarce in 2002, the college chose Texas Instruments' TI-89 graphing calculator to fulfill the program's hand-held computational needs. Many in the surveying and allied disciplines have mourned the demise of the HP-48, but the TI-89 is a powerful, and perhaps most importantly, economical and available alternative to HP-48s or Personal Data Assistants, which can be easily integrated into college-level surveying curricula. This paper explores the TI-89's suitability for use as an instructional tool in the classroom and describes SurvAid, a set of coordinate geometry (COGO) and other discipline-specific software applications designed for surveying students' use written especially for the TI-89.

Introduction

Since its release in 1990, Hewlett-Packard's HP-48 series of programmable graphing calculators has been a mainstay of surveyors and surveying educators in the United States. These powerful machines were reliable and expandable and could be configured to work as desktop computational devices or they could be interfaced with electronic total stations to function as data collectors and field computational tools. This platform for years was actively supported by several commercial software developers whose applications enjoyed widespread use in the surveying and allied disciplines. Moreover, the HP-48's programming environment and equation solver utilities were easily accessible and readily adaptable, allowing users to develop their own custom software tools (Paiva 2004).

In Peninsula College's two-year Surveying-Geomatics programs, HP-48s were used in all of these modes: by students as a calculating device for mathematics and science courses, as a desktop coordinate geometry tool in more advanced surveying coursework; and also as a common data collection platform for several different types of total stations. In 2002, when HP-48s became difficult to come by, the college's Surveying-Geomatics Advisory Board searched for a replacement student computational platform. The board wanted to adopt a machine that possessed the features that had made the HP-48 series calculators so useful for this discipline: a full-featured scientific and graphing function set for math and science courses, with plenty of memory for data storage and a programmable capability for advanced surveying applications. Reasonable cost, reliability, and easy availability were important considerations because students cannot use what they cannot buy or cannot afford to buy. For these reasons, Personal Data Assistants (PDAs) were eliminated from consideration, as were laptop computers. The high cost of PDAs and commercial surveying software (or laptop computers and software, for that matter) was considered as prohibitive for most students. The board finally settled upon Texas Insturments' TI-89 family of calculators to fulfill the program's instructional needs and the student's computational needs formerly met by the now discontinued HP-48.

Meet the TI-89

The TI-89 in its latest incarnation, known as the "TI-89 Titanium," is relatively inexpensive and is widely available (Wal-Mart sells them for $149), thus meeting the important availability criterion (Figure 1). It also has ample memory with 4.0MB of random access (RAM) and flash read only (ROM) memory for user applications and data. Like the HP-48, this calculator uses a system of "folders" similar to those found on a computer's hard disk for organizing data, variables, and software applications but, unlike the HF product, subfolders are not allowed. Its function and command set is vast, including specialized algebra, calculus, general mathematics, statistics, and matrix functions, as well as an extensive set of graphics, and list, string, and programming commands-over 400 functions and commands in all. Its user accessible programming environment uses a variant of the widely used BASIC programming language, but users can also purchase a software developer's kit for creating machine language applications (http://education.ti.com/us/resources/developer/8992/hilight.html).

The calculator has a high contrast, 100x160 pixel, eight-line liquid crystal display and is equipped with a sophisticated user interface that uses a combination of pull-down menus, dialog boxes, and icons to communicate with its users. The calculator can also interface with IBM-compatible and Apple computers; the TI-89 Titanium is supplied with a USB interface cable and TI Connect(TM) communication software for this purpose (TI Guidebook). The machine uses a Motorola 68000 CPU and is, in general, more responsive than the HP-48 it replaces.

From an instructional perspective, the TI-89 is just as powerful and just as capable in the classroom as the HP-48. Texas Instruments sells a liquid crystal monitor (the TI ViewScreen(TM); Figure 2) and a compatible calculator for under $400, which, when used in combination with an overhead projector, allows instructors to project an enlarged image of the calculator's display onto a projection screen. A similar device was available for Hewlett-Packard products, and they have proven very effective for demonstrating complex problems, functions, or programs to a group of students.

Another device, the TI-89 Titanium Presentation Link(TM) (about $50), allows users to connect any TI89 Titanium calculator to a ViewScreen(TM) monitor. It is also possible to link the calculator to a video monitor using a TI Presenter (about $235), and thus to a data projector.

Texas Instruments is committed to supporting its products, and so it maintains a web page devoted to these and other educational products. Visit http://education.ti.com for more information on TI calculators and accessories and for links to dealers. Operating system updates and a variety of flash applications are also available for downloading from the web site. Many are free; some are available for a nominal fee.

The TI CellSheet is a typical flash application: Once installed in the TI-89's read only memory area, this application allows users to import and export Microsoft Excel® spreadsheets between the calculator and an Excel® equipped PC. The TI-89 also contains a utility called the "numeric solver" (known as the "equation solver" in the HP-48 universe). At Peninsula College, the HP-48 version of this utility was heavily used in several courses in which students, as part of their coursework, were required to create a library of software tools for geodetic, state plane, road design, and general surveying applications, so this is a welcome and happily familiar feature of the TI-89.

Hand-held Calculators' Role in a Surveying-Geomatics Curriculum

Hand-held calculators play a role in the surveying program at Peninsula College which extends far beyond that required to support mathematics and science courses. Students receive instruction in "manual" computational methods (using calculators) before they proceed to personal computer (PC) based data-processing techniques. For example, basic coordinate geometry concepts are introduced using hand-held calculators, while CAD-based coordinate geometry is presented in subsequent courses.

Once manual methods have been mastered, students receive fairly complex homework assignments that consist of computational problems typical of those encountered by practitioners (e.g., subdivision of fractional Public Land Survey System sections). These assignments are meant to be solved with the aid of a hand-held calculator, not with QVD or computer-based COGO applications. The rationale for this approach is that it provides students with opportunities for practicing typical computational processes so as to reinforce ideas that might otherwise be lost in a series of keystrokes and software-specific menu options if PC-based applications were used instead of the more tactile hand-held calculator.

Additionally, and as strange as it may seem in this day and age, not all students own or have access to personal computers at home. Moreover, many do not possess the financial resources necessary to purchase a PC, let alone the discipline-specific software that would be required for solving many complex surveying problems. The hand-held calculator, at half the cost of a PDA or 1/10 the cost of a good laptop computer (sans surveying software) can therefore provide students with the computational power required for solving rather complex surveying problems outside the classroom at a price they can more readily afford.

While the hand-held calculator will continue to have a place in the surveying curriculum at Peninsula College, it must be recognized that without a software component these devices will not be used to their fullest potential. When the HP-48 was the computational tool of choice, Peninsula College students received, free of charge, a custom-built suite of 2D coordinate geometry routines for their use (but only after manual methods had been mastered!). This software allowed students to take on more and more complex computational assignments than would have been possible without it. Unfortunately, when the advisory board recommended the TI-89 as a replacement platform, an Internet search yielded only one extant COGO application for the TI-89, the neXus suite written by a British firm (Dawson 2001). But since that program did not meet all of our needs, it became necessary to write a new set of programs that would.

Introducing SurvAid

SurvAid is a set of over 40 software modules and utilities (including coordinate geometry and other tools) designed for solving many typical surveying problems. The routines are written in TI Basic, a user-accessible version of the BASIC computer language that is integral to the TI-89. Most of these routines are stand-alone applications that access a common data file.

This modular approach has advantages and disadvantages. While the modular design of SurvAid makes it possible to distribute discrete portions of the software to students only after they have successfully mastered specific manual techniques, the routines probably use more memory resources than they would if a more integrated approach were used. All told, SurvAid requires a minimum of about 56 kilobytes of memory.

The current set of 45 SurvAid routines, several system variables, and current project data files reside in a folder called SURVAID. Project data files-consisting of point IDs, northings, eastings, datum, zone, and scale factor data-are stored in a PROJECTS folder. Lambert projection state plane grid zone constants can be stored in a ZONES folder. The user either creates a new project file, or loads an existing one, and then uses SurvAid's COGO and other routines to view or manipulate the coordinates of existing points, create new ones, or to compute and view other associated data such as bearings, distances, and other spatial relationships.

The current version of SurvAid includes specialized unit conversions; sexagesimal mathematics functions; and COGO routines which include three different traverse modes, side shots, inverse, radial stake-out, line-line intersections, polygon areas, coordinate system translation, rotation and scale, compass rule adjustment, and mid-point and proportionate measure. Also included are a set of Lambert projection State Plane Coordinate System programs for computing the scale, elevation and combined grid factors, mapping angle, and the latitude-longitude / northing-easting of a stored point or a point input by the user.

Supporting routines allow users to load and store zone constants for any Lambert projection state plane zone. Other data management routines allow users to create, load, and merge project coordinate files, and enter and assign, view, recall or edit coordinates. In addition to the software itself, I have also prepared a 19,000-word user's guide for students. I am currently negotiating with Peninsula College for a spring 2005 publication and release of SurvAid. The various functions, utilities, and programs of SurvAid are described in Appendix A.

Planned future enhancements include additional cadastral routines: BLM boundary line adjustment and modified single proportionate measure, also Transit and Crandall's rule coordinate adjustments, improved coordinate data import and export routines, and enhanced traverse routines that can handle horizontal curves.

SurvAid's Origins: TI to HP and Back Again

SurvAid's programs are inspired by a set of routines originally written for a Texas Instruments TI-59 programmable calculator by a co-worker of mine, Dean Allen Mazur, in the late 1970s. Dean's program was used by us in the Clallam County (Washington) Engineer's office to check short plats for mathematical closure. Programs for this machine were recorded on magnetic cards and had to be reloaded each time the calculator was switched off.

When the office purchased Hewlett-Packard HP-4 Is to replace our TIs, the task of rewriting Dean's programs to HP format fell to me. A few years later, working as a party chief for the Washington Department of Natural Resources, I again rewrote and expanded the short plat program to meet my computational needs and those of my field crew. At the time, personal desktop computers were still relatively rare, primitive, and expensive, and hand-held programmable calculators were the most powerful, inexpensive COGO hardware tools available. I subdivided many sections and balanced many traverses using my trusty HP-41!

Alas, the HP-41 was discontinued, to be replaced by the HP-48. A colleague of mine, James Wengler, PLS, had written an excellent COGO program for the HP-48, and we adopted his program as our main field computational tool in the early 1990s. When I began teaching at Peninsula College, James graciously allowed me to pass on a version of his software to my students. Peninsula College's surveying students used the HP-48 and James' software until June 2004. With the development of SurvAid, we have completed our transition to the Texas Instruments platform.

System Requirements for SurvAid

SurvAid will run on hardware versions 2.00 (Figure 3) and 3.00 (TI-89 Titanium) of Texas Instruments' TI-89 series of hand-held graphing calculators. Both hardware versions may be available in stores by the time this paper is published, but the "Titanium" version is probably a better choice as it contains about 3.5 times as much memory as the older version, and it is also preloaded with several useful flash applications, chief among these being the "Organizer," a personal data assistant application which will be especially useful for students.

While SurvAid does not require the latest hardware version, TI-89 v. 2.00 users should update the operating system of their units to version 2.09, which is available from the TI website. This operating system adds a system clock and a graphical user interface that is identical in operation to the operating system used in the newer Titanium model, and it is required if one wishes to download and use the Organizer program (which is also available from the TI website-both are free).

Conclusions

Many in the surveying and allied disciplines are mourning the demise of the HP-48, but the TI-89 is as powerful, and perhaps most importantly, economically attractive alternative that can be easily integrated into a college-level surveying curriculum. One thing that seems to be preventing more widespread use of this particular machine throughout the discipline is a lack of appropriate software, but the TI-89 is easily programmed for surveying applications by anyone who is familiar with the BASIC computer language, as is evidenced by my suite of coordinate geometry programs called SurvAid.