Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Distance Measurement by Electronic method
Based on Hard-wired algorithm
Relay on Propagation, Reflection and
subsequent re...
Short Range
• Range<3km
• ±(0.2+1mm/km)
accuracy
• Telluromerter
Medium Range
• Range<25km
• ±(5+1mm/km)
accuracy
• Geodim...
On the basis of carrier wave Used
Microwave
• Long range
instrument
• Freq range
3 -30GHz
• Telluromerter
Visible light
• ...
Geodimeter
Heavier Instrument
Observations are limited to nights
only
Instrument set up at one end &
reflector at other en...
Generation Modulation Transmission Propagation
ReflectionReceptionDemodulation
Distance
Measured
Carrier Wave
High freq Wave
Measuring
Signal
Measured Signal
Setting up Instrument is centered over a station by means of
tribrach. Reflector are set over the remote station on tribra...
Distance = Velocity x Time
2
Time is too short- difficult
to measure
Phase Difference method
is Used
Distances are calculated
Length of wave is known
No. Of Completed & Uncompleted Wave Is Measured Equivalent Distance when
...
Personal Errors
Instrumental Errors
Natural Errors
Personal
Error
Inaccuracy in
Initial Setups
Instrument &
Reflector
measurements
going Wrong
Atmospheric
Pressures &
Temper...
Instrumental
Error
Calibration
Error
Chances of
getting
unstable
frequent errors
Errors Shown
by Reflector
Natural
Error
Atmospheric
variations in
Temperature,
Pressure &
Humidity
Multiple
Refraction of
Signals
Any Question?
Electronic distance measurement (EDM)
Upcoming SlideShare
Loading in …5
×

Electronic distance measurement (EDM)

Edm is a surveying instrument used to measure the distance electronically. This Surveying Instrument is used in triangulation to measure the length of Base line because more accuracy is required to measure the length of base line.

  • Be the first to comment

Electronic distance measurement (EDM)

  1. 1. Distance Measurement by Electronic method Based on Hard-wired algorithm Relay on Propagation, Reflection and subsequent reception of electro-magnetic Wave Electronic Angle Measurement (Combined the function of theodolite & EDM – TOTAL STATION)
  2. 2. Short Range • Range<3km • ±(0.2+1mm/km) accuracy • Telluromerter Medium Range • Range<25km • ±(5+1mm/km) accuracy • Geodimeter Long Range • Range<100km • ±(10+3mm/km) accuracy • Distomat On the basis of Range of Operation
  3. 3. On the basis of carrier wave Used Microwave • Long range instrument • Freq range 3 -30GHz • Telluromerter Visible light • Medium range instrument • Freq used 5 x 1014 Hz • Geodimeter Infrared • Short range instrument • Freq used 3 x 1014 Hz • Distomat
  4. 4. Geodimeter Heavier Instrument Observations are limited to nights only Instrument set up at one end & reflector at other end Light Radio Waves are used Tellurometer Lighter Instrument Observations may be made during the day as well as during the night Two identical instruments at either ends High Frequency Radio Waves are used
  5. 5. Generation Modulation Transmission Propagation ReflectionReceptionDemodulation Distance Measured
  6. 6. Carrier Wave High freq Wave Measuring Signal Measured Signal
  7. 7. Setting up Instrument is centered over a station by means of tribrach. Reflector are set over the remote station on tribrach Aiming Instrument is aimed at prism by using sighting device or theodolite telescope Measurement Operator presses the measure button to record the slope distance that displayed on LCD panel Recording Information on LCD panel can be recorded manually or automatically
  8. 8. Distance = Velocity x Time 2 Time is too short- difficult to measure Phase Difference method is Used
  9. 9. Distances are calculated Length of wave is known No. Of Completed & Uncompleted Wave Is Measured Equivalent Distance when Received Signal Out of Phase Length of wave = Phase Difference of wave transmitted & received ʎ = Wavelength n = No. of wave travelled
  10. 10. Personal Errors Instrumental Errors Natural Errors
  11. 11. Personal Error Inaccuracy in Initial Setups Instrument & Reflector measurements going Wrong Atmospheric Pressures & Temperature Determination errors
  12. 12. Instrumental Error Calibration Error Chances of getting unstable frequent errors Errors Shown by Reflector
  13. 13. Natural Error Atmospheric variations in Temperature, Pressure & Humidity Multiple Refraction of Signals
  14. 14. Any Question?

×