| record number: | 92 |
| instrument type: | electronic distance meter |
| manufacturer: | HP |
| serial number: | 1226A00795 |
| model: | 3800B |
| weight: | 8.90 kg |
| dimensions (l/w/h): | 33/32/32 cm |
| year of manufacture: | 1969 |
| type of distance meter: | phase-shift principle, middle range |
| instrument set up: | plumb bob, circular level |
| precision: | 5 mm; 7 ppm |
| range: | 2300 m to 3000 m with three prisms |
| time of one measurement: | less than 2 minutes |
| distance reading: | analog, on the display – resolution 10 mm |
| light source: | laser diode |
| carrier wave: | 0.840 μm |
| measurement frequency: | 15 MHz |
The phase precision distance meter was made in 1969. Its range is between 2.3 km and 3 km (with three prisms on the reflector). The integrated light source is a laser diode that generates invisible IR light at a wavelength of 840 nm. The measurement frequencies are switched manually. It takes about 2 minutes to measure the distance, depending on the skills of the operator. The instrument, the first electronic distance meter at the Faculty, was a marvel of technology for generations of students in the 1970s, as before that time, lengths had been measured only optically and with measuring tapes.
The instrument is in the same condition as it was when it was originally taken out of service.