Electronic Distance Measurement Instruments Research Articles

Analysis of development tendencies of metrological technologies to control rangefinders of an electronic distance measurement instruments

Analysis of development tendencies of metrological technologies to control rangefinders of an electronic distance measurement instruments

Short Baseline Calibration using GPS and EDM Observations

We conducted a baseline comparison for instrument calibration using GPS (Global Positioning System) and EDM (Electronic Distance Measurement) observations. The experiment was carried out at campus of the Autonomous University of Sinaloa (UAS) in Culiacan, Mexico. The main objective of this research was to establish a short (∼125 m) baseline for calibration of geodetic-grade GPS and EDM instruments of different commercial brands to validate the precision specifications offered by the manufacturers of such instruments. We compared three types of geodetic-grade GPS receivers: Topcon Hiper Lite +, Ashtech Z-Xtreme and Leica SR500 and three types of EDM: Topcon GTS-236W, Pentax R-326EX and Leica TC-407. For the experiment, the baseline components were computed by using ionosphere-free double-difference (DD) GPS carrier phase observations processed using the PAGES software (Program for the Adjustment of GPS EphemerideS). The GPS data were processed with a 1-second sampling rate, 10-degree cutoff angle, and precise GPS orbits disseminated by IGS (International GNSS Service). The length of the calibration baseline was also obtained by averaging 20 measurements of line length directly recorded by the three different EDM instruments. GPS results agree among different brands with differences of ±2mm in contrast with the resulting EDM values that differ within ±3mm.

Atmospheric Attenuation and Scintillation Effects on the Range of EDM Instruments

AbstractThis investigation aimed to study the range of various electronic distance measurement (EDM) instruments used in survey engineering, assuming different weather conditions and different terrain altitudes, by controlling every parameter influencing the measurements and contrasting the results with the information provided by the manufacturers. The first step consisted of determining the EDM real optical wavelength to be used for control against the manufacturers’ provided values. Consequently, a spectroscopy test of the lasers installed in every EDM instrument was carried out at the ESA-VSC [European Space Agency (ESA) and Val Space Consortium (VSC)] laboratory. The second step was to study the total measurement range of each instrument in different weather conditions and at different altitudes. Three experimental tests were carried out at three different locations in eastern Spain, separated by distances of less than 90 km, and altitudes ranging from sea level to about 2,000 m. Owing to the influen...

Advanced Techniques for Travel Time Data Collection

Travel time information is becoming more important for applications ranging from congestion measurement to real-time travel information. Several advanced techniques for travel time data collection are discussed, including electronic distance-measuring instruments (DMIs), computerized and video license plate matching, cellular phone tracking, automatic vehicle identification (AVI), automatic vehicle location (AVL), and video imaging. The various advanced techniques are described, the necessary equipment and procedures are outlined, the applications of each technique are discussed, and the advantages and disadvantages are summarized. Electronic DMIs are low in cost but typically limited to congestion monitoring applications. Computerized and video license plate matching are more expensive and would be most applicable for congestion measurement and monitoring. Cellular phone tracking, AVI, and AVL systems may require a significant investment in communications infrastructure, but they can provide real-time in...

Advanced Techniques for Travel Time Data Collection

Travel time information is becoming more important for applications ranging from congestion measurement to real-time travel information. Several advanced techniques for travel time data collection are discussed, including electronic distance-measuring instruments (DMIs), computerized and video license plate matching, cellular phone tracking, automatic vehicle identification (AVI), automatic vehicle location (AVL), and video imaging. The various advanced techniques are described, the necessary equipment and procedures are outlined, the applications of each technique are discussed, and the advantages and disadvantages are summarized. Electronic DMIs are low in cost but typically limited to congestion monitoring applications. Computerized and video license plate matching are more expensive and would be most applicable for congestion measurement and monitoring. Cellular phone tracking, AVI, and AVL systems may require a significant investment in communications infrastructure, but they can provide real-time information. Video imaging is still in testing stages, with some uncertainty about costs and accuracy.

Calibration baselines in canada

The establishing, measuring and monitoring of Electronic Distance Measurement (EDM) cali¬bration baselines in Canada is a joint program of the Geodetic Survey of Canada and provincial, territorial and municipal surveying agencies. Since its establishment in 1971, the 2.3 km National Geodetic Baseline (NGBL) in Ottawa has been used as the reference baseline for other calibration baselines; two precise EDM instruments, the Mekometer ME3000 and the Geomensor CR204, have been used to transfer the length standard of the NGBL to baselines across Cana¬da. Thirty-six calibration baselines, established as part of the National Baseline Program, now exist. The Geodetic Survey strives to maintain the published values of interpier distances at the highest accuracy possible. To this end, extensive remeasurements are being planned. For longer distances which may be required to calibrate or check GPS instruments, a calibration network with lines up to 222 km is being established.

THE LAGOS 11.4 KM BASELINE

Abstract An 11.4 km baseline has been established for calibration of electronic distance-measuring instruments in Lagos, as well as for research work and for calibration of the triangulation network tied to the African Doppler satellite programme currently in progress. This line is part of the proposed 44 km on the same site on the boundary of Lagos and Ogun States. The baseline was measured with an Aga Geodimeter model 8 using a laser as carrier.Because of higher frequency stability, only the U 1 frequency is made functional, while the remaining three frequencies (U 2–U 4) have been disconnected. In addition, a microwave instrument, Sial MD-60, was employed to produce the coarse measurement. The standard error attained for the baseline was better than 1 ppm.The difference in ground elevation does not exceed 70 m, while towers of 30–40 m high are placed at the terminals of the line. The measuring beam runs well above the treetops, which average 10 min height. Two 40 m meteorological towers were built besi...

Improved instrumental accuracy for microwave electronic distance-measuring instruments

The measurement centre of microwave electronic distance-measuring instruments (EDMIs) is affected by antenna VSWR in the transmit plane. This results in the measuring centre of the instrument changing with temperature as the frequency of the microwave transmitter source changes. A new technique is described which virtually eliminates this source of error.

Fifty Years in Surveying – Mapping – and the Future

The tools and techniques of surveying and mapping have undergone revolutionary changes during the last 50 years. Automatic levels and electronic distance-measuring instruments have simplified and speeded field survey work. Survey computations and adjustments that were executed by laborious, time-consuming methods are now carried out rapidly by means of electronic computers. Geodetic surveys of greatly increased accuracy can now be made with the aid of active and passive earth satellites. Photogrammetric procedures, which became the standard means for producing maps after World War II, are being further improved by the use of radar, infrared, color, and other remote-sensor techniques. Map-drafting methods using pen-and-ink drafting and copperplate engraving have been replaced by more efficient scribing procedures. Great strides have been made in the automation of various phases of cartography. New methods of map presentation, such as the orthophotomap, offer an improvement over conventional line maps in some instances.

Simultaneous adjustment of angular and distance measurements

The development and use of electronic distance-measuring instruments has posed the problem that many of our triangulation networks have become a mixture of triangulation, trilateration, and traverse, especially in the areas where control is needed for the interstate highway program. A method of adjusting triangulation, trilateration, and traverse simultaneously is presented in this paper. The formulas, methods, and techniques were devised in an attempt to make an adjustment that gives a satisfactory solution with minimum distortion to both angular and distance measurements. A presentation of several approaches to the problem is made with emphasis given to the application of these methods to an intermediate-sized electronic computer.