Date of intro: jan-1978,
Classification: / Documentation / Article / Navigation (topography, surveying),
Related with: HP_calcs: 97 (version-1),
Publisher-1: VPK, Publisher-2: GUBLER, E.,
Info: The article describes how the Swiss Federal Office of Topography used the HEWLETT-PACKARD: 97 programmable calculator as an intermediate solution between traditional handwritten field books and expensive fully automated surveying systems.
At the time, fully automatic surveying instruments already existed, but their high purchase costs made them economical only when used intensively.
For applications such as precision levelling and triangulation,
the authors therefore wanted a cheaper system that could reliably record measurements, perform calculations directly in the field, detect errors, and reduce the amount of data that later had to be processed in the office.
The HP: 97 was selected because it offered sufficient program and data memory, programs could easily be loaded using magnetic cards, and its built-in thermal printer could permanently record measurements and calculated results on paper.
The calculator was placed in a protective, water-resistant carrying case.
As shown in the photographs on page 3, the complete field setup weighed about 4kg and could be carried with two straps and operated with one hand.
It could also function at temperatures down to approximately -3°C, although the printer became somewhat fainter.
Use in national precision levelling:
The system proved particularly successful for Swiss national levelling.
Surveyors entered information such as the date, time, benchmark and levelling-staff numbers, temperatures, distances, and height readings.
The HP: 97 immediately checked measurements for inconsistencies.
For example, it warned the operator when a reading did not correspond with the calculated mean and displayed differences between repeated height measurements.
Incorrect entries could then be corrected immediately.
At the end of a levelling section, the calculator printed the raw height differences, temperature corrections, corrected mean height difference, total measured distance, and differences between backsight and foresight distances.
The example printout shown on page 4 (Figure 3) illustrates such a measurement record for a two-station levelling section.
As a result, daily manual checking calculations were largely eliminated, and only two values per measured section needed to be transferred manually for subsequent processing.
Other surveying applications:
The HP: 97 was also successfully adapted for distance measurements using the Geodimeter 6 BL and 8.
A program recorded resolver readings, performed logical checks, calculated the raw distance, and allowed corrections without repeatedly entering all measurements.
This produced significant time savings both in the field and during office processing.
Its use for **direction/set measurements** was less successful.
Although the calculator could process up to five sets with a maximum of nine directions and calculate the set mean and mean error, its limited program and data memory restricted the number of measurements and correction options.
The authors therefore considered more memory necessary for this type of surveying.
Main conclusion:
The article concludes that programmable pocket computers could make field surveying substantially more efficient. The cost of the HP: 97 system could reportedly be recovered after only a few weeks of field use through savings in manual checking and calculation time.
The solution fully met the authors' requirements for national levelling and Geodimeter distance measurements, although more memory was required for direction measurements.
The authors expected continuing advances in electronics to overcome these remaining limitations.