surveying file the define about electronic distance measurement and types of EDM

1. HOPE ENTERPRISE
UNVERSITY COLLEGE
SURVEYING ASSIGNMENT
GROUP MEMBERS
• ABIGIYA HABTU
• ABENEZER KEBEDE
• HEWAN ASSEFA
• BITANYA KASAYE
• JEWAD SHEMSU
• NATNAEL BIRHANU
• HENOK AYALEW

2. Electronic distance measurement
• Electronic distance measurement (EDM) is a method of
determining the distance between two points using
electromagnetic waves, most commonly light waves or
microwaves. It's a significant advancement over
traditional methods like tapes and chains, offering greater
accuracy, speed, and range.
• EDM instruments are highly reliable and convenient
pieces of surveying equipment and can be used to
measure distances of up to 100 kilometers.

3. • EDM instruments come in
various types
• A Theodolite is a
instrument for measuring
both horizontal and vertical
angles, as used in
triangulation networks.

4. • Total Stations: These
combine an EDM with an
electronic theodolite,
allowing for angle and
distance measurements
simultaneously. They're
widely used in surveying
and construction.

5. • Laser Distance
Meters: These compact
and portable instruments
use laser light for
measurements, making
them ideal for shorter
distances. They're
commonly used in home
improvement and DIY
projects.

6. • Radar Distance Meters:
• These instruments use radio
waves for longer distances,
reaching up to several
kilometers. They're used in
applications like aerial surveys
and traffic monitoring.

7. Variation in Temperature
Temperature Variation Error - (TVE)
• refers to the change in measurement accuracy or
reading caused by variation in temperature.
• A measured estimate of the maximum possible
positioning or measurement error induced solely by
deviation of the environment from average thermal
conditions. Usually specified for a given length of
time such as 24 hours.

8. 1. Thermal Gradient Error:
Temperature gradient error occurs when there is a temperature
difference across a measurement system. This error can be
calculated using the formula:
ΔT = α × L × ΔTenv

9. where:
ΔT is the temperature variation error
α is the thermal coefficient of the material (°C/m)
L is the length of the measurement system (m)
ΔTenv is the temperature difference across the system (°C)
For example, if you have a temperature sensor with a wire that
is 2 meters long and the temperature difference between the
sensor and the measurement device is 5°C, and the thermal
coefficient of the wire is 0.01°C/m, the temperature variation
error would be:
ΔT = 0.01°C/m × 2 m × 5°C = 0.10°C

10. 2. Sensor Nonlinearity:
• Sensor nonlinearity occurs when the sensor's output deviates
from the expected linear relationship with temperature. To
calculate this error, you would need the sensor's datasheet,
which typically provides a transfer function or calibration
curve.
• Let's say you have a temperature sensor with a nonlinear
output. The datasheet provides a calibration curve equation:
Vout = aT^2 + bT + c, where T is the temperature in °C, and a,
b, and c are constants. If the actual temperature is 50°C and
the sensor's output is 48.5°C, the temperature variation error
due to nonlinearity would be:

11. 3. Hysteresis:
Hysteresis is the difference in measured values when the
temperature is increasing versus when it is decreasing. To
calculate hysteresis error, you would need to measure the
temperature at both the ascending and descending temperature
points and find the difference.
• For example, if you measure a temperature of 60°C when
the temperature is increasing and 58.5°C when it is
decreasing, the hysteresis error would be:
ΔT = Temperature (increasing) - Temperature (decreasing)
• = 60°C - 58.5°C = 1.5°C

12. THANK YOU