• EDM – Electronic distance measurement eqp.
• Auto level.
• Digital level.
• Total station.
• GPS – global positioning system.
• Now separate EDM are not very popular , instead
Total Station which have in built EDM is being
• Measurement of distance is accomplished with a
modulated microwave or infrared carrier signal,
generated by a small solid-state emitter within
the instrument's optical path, and bounced off of
the object to be measured. The modulation
pattern in the returning signal is read and
interpreted by the onboard computer in the
EDM. The distance is determined by emitting and
receiving multiple frequencies, and determining
the integer number of wavelengths to the target
for each frequency.
Hand held EDM
• Very handy,
• Can be used with
accuracy of 10mm or
• Useful for remote
contact wire etc.,
• Now most commonly
instruments are - Auto
– Auto level, as name
sounds it has a auto
level compensator and
if instrument goes out
of level within it’s
• With auto level:-
–Survey work can be done fast,
–Less chances of error,
–Magnification available is more,
–Range is more,
–Image is erect so less chances of
• They are not popular instead
auto levels are more extensively
• The Trimble DiNi Digital Level :
Determine accurate height
information 60% faster than with
• Eliminate errors and reduce
rework with digital readings
• Transfer data to the office easily
• Measure to a field of just 30 cm
• Recently electronic digital levels have evolved as a
result of development in electronics and digital image
• Digital levels use electronic image processing to
evaluate the special bar-coded staff reading.
• This bar-coded pattern is converted into elevation and
distance values using a digital image matching
procedure within the instrument.
SALIENT FEATURES OF
• Fatigue-free observation as visual staff reading by the
observer is not required.
• User friendly menus with easy to read, digital display
• Measurement of consistent precision and reliability
due to automation.
• Automatic data storage eliminates booking and its
• Fast, economic surveys resulting in saving in time (up
to 50% less effort has been claimed by
• Data on the storage medium of the level can be
downloaded to a computer enabling quick data
reduction for various purposes.
COMPONENTS OF DIGITAL
• The following discussion on digital levels has been
primarily taken from Schoffield (2002).
• Main components of digital level consist of two parts:
Hardware (Digital level and levelling staff) and
• Both digital level and associated staff are
manufactured so that they can be used for both
conventional and digital operations.
• Typically digital level has the same optical and
mechanical components as a normal automatic level.
• However, for the purpose of electronic staff reading a
beam splitter is incorporated which transfers the bar
code image to a detector diode array.
• The light, reflected from the white elements only of
the bar code, is divided into infrared and visible light
components by the beam splitter.
• The visible light passes on to the observer, the
infrared to diode array.
• The acquired bar code image is converted into an
analogous video signal, which is then compared with
a stored reference code within the instrument.
• Various capabilities of digital levels are as follows:
1. measuring elevation.
2. measuring height difference.
3. measuring height difference with multiple
6. setting out with horizontal distance
7. levelling of ceilings
PRINCIPLE OF EDMI
• The general principle involves sending a modulated
Electro-magnetic (EM) beam from one transmitter at
the master station to a reflector at the remote station
and receiving it back at the master station.
• The instrument measures slope distance between
transmitter and receiver by modulating the continuous
carrier wave at different frequencies, and then
measuring the phase difference at the master station
between the outgoing and the incoming signals. This
establishes the following relationship for a double
• The following photographs show different types of
OPERATION WITH EDMI
• Measurement with EDMI involves four basic steps:
(a) Set up
• Setting up: The instrument is centered over a station
by means of tribrach. Reflector prisms are set over
the remote station on tribrach.
• Aiming: The instrument is aimed at prisms by using
sighting devices or theodolite telescope. Slow motion
screws are used to intersect the prism centre. Some kind
of electronic sound or beeping signal helps the user to
indicate the status of centering.
• Measurement: The operator presses the measure button
to record the slope distance which is displayed on LCD
• Recording: The information on LCD panel can be
recorded manually or automatically. All meteorological
parameters are also recorded.
ERROR IN MEASUREMENT
1. Instrument errors :
• centering at the master and slave station.
• pointing/sighting of reflector.
• entry of correct values of prevailing atmospheric
2. Atmospheric errors :
Meteorological conditions (temperature, pressure,
humidity, etc.) have to be taken into account to
correct for the systematic error arising due to this.
These errors can be removed by applying an
appropriate atmospheric correction model that takes
care of different meteorological parameters from the
3. Instrumental error :
Consists of three components - scale error, zero error
and cyclic error. These are systematic in nature
• Basic Principle
A total station integrates the functions of a
theodolite for measuring angles, an EDM for
measuring distances, digital data and a data recorder.
Examples of total stations are the Sokkia Set4C and
the Geodimeter 400 series. All total stations have
similar constructional features regardless of their age
or level of technology, and all perform basically the
• Total solution for surveying
• Most accurate and user
• Gives position of a point (x, y
and z) w. r. t. known point
• EDM is fitted inside the
• Digital display,
• On board memory to store data,
• Compatibility with computers,
• Measures distance and angles and displays
• Auto level compensator is available,
• Can work in lesser visibility also,
• Can measure distances even without prismatic
target for lesser distances,
• Is water proof,
• On board software are available,
• Can be used for curve layout after feeding data.
Total Stations can be used for:
• General purpose angle measurement
• General purpose distance measurement
• Provision of control surveys
• Contour and detail mapping
• Setting out and construction work
• Most TS have on-board storage of records using
PCMCIA memory cards of different capacity. The
card memory unit can be connected to any external
computer or to a special card reader for data transfer.
• The observations can also be downloaded directly
into intelligent electronic data loggers. Both systems
can be used in reverse to load information into the
• Some instruments and/or data loggers can be
interfaced directly with a computer for immediate
processing and plotting of the data (Kavanagh, 2003).
FIELD OPERATION WITH TS
• Various field operations in TS are in the form of wide
variety of programs integrated with microprocessor
and implemented with the help of data collector.
• All these programs need that the instrument station
and at least one reference station be identified so that
all subsequent stations can be identified in terms of
(X, Y, Z). Typical programs include the following
• Point location
• Missing line measurement (MLM)
• Remote distance and elevation measurement
• Offset measurements
• Layout or setting out operation
• Area computation
• For details on above functions, one can refer to the
user manual of any TS.
Different Types of TS and
Factors influencing the use of Total Stations:
• A clear line of sight between the instrument
and the measured points is essential.
• The precision of the instrument is dependent
on the raw repeatabilities of the direction and
• A well defined measurement point or
target/prism is required to obtain optimal
precision and accuracy.
• The accuracy of direction and distance
measurement is subject to a number of
instrumental errors and the correct field
Auxiliary Equipment Required
• Targets or Prisms to accurately define the
target point of a direction measurement.
• A data recorder if one is not integrated into
the total station.
• A download cable and software on a PC to
capture and process the captured digital data
to produce contour and detail maps.
–Display at target also,
–No need of operator on
–Moves automatically to
automatically at target at
–Can be integrated with
• Science and art of obtaining information about an
object, area, or phenomenon through the analysis of
data acquired by a device that is not in contact with
the object, area, or phenomenon under investigation
REMOTE SENSING SYESTEM
• A typical remote sensing system consists of the
(c) processing (ground) segment
• Various stages in these sub-systems are indicated in
the next figure.
• The electro-magnetic (EM) energy forms the
fundamental component of a RS system
APPLICATION OF REMOTE
• Crop condition assessment.
• Crop yield estimation
• Infrastructure mapping.
• Land use change detection.
• Future urban expansion planning
MITIGATION PREPAREDNESS RESCUE RECOVERY SATELLITES USED:
Identifying escape routes;
storm surge predictions.
Cyclone Lehar by KALPANA 1 Cyclone Helen by Mangalayan
MITIGATION PREPAREDNESS RESCUE RECOVERY SATELLITES USED
Building stock assessment;
Planning routes for search
identifying sites for
InSAR; SPOT; IRS
The World Agency of Planetary Monitoring and Earthquake Risk Reduction (WAPMERR) uses remote sensing
to improve knowledge of building stocks — for example the number and height of buildings. High resolution imagery can
also help hazard mapping to guide building codes and disaster preparedness strategies.
MITIGATION PREPAREDNESS RESCUE RECOVERY SATELLITES USED
AMSR-E; KALPANA I;
Sentinel Asia — a team of 51 organisations from 18 countries — delivers remote sensing data via the Internet as
easy-to-interpret information for both early warning and flood damage assessment across Asia.
It uses the Dartmouth Flood Observatory's (DFO's) River Watch flood detection and measurement system, based on
AMSR-E data, to map flood hazards and warn disaster managers and residents in flood-prone areas when rivers are likely
to burst their banks.
Flood In Uttarakhand Flood In Assam
DISASTER MITIGATION PREPAREDNESS RECOVERY RESCUE SATELLITES USED
DROUGHT Risk modelling;
land and water
crop water requirement
FEWS NET; AVHRR;
VOLCANO Risk modelling;
digital elevation models.
Mapping lava flows;
MODIS and AVHRR;
FIRE Mapping fire-prone
monitoring fuel load;
predicting spread/direction of
Sentinel Asia; AFIS
LANDSLIDE Risk modelling;
Monitoring rainfall and slope
InSAR; SPOT; IRS
8th October 10th October 11th October
7th October, 2013: Indian Meteorological Department
received information from KALPANA I, OCEANSAT and INSAT
3A Doppler radars deployed at vulnerable places, with over-
lap, sensors in the sea and through the ships, about a
cyclone forming in the gulf between Andaman Nicobar and
Thailand named PHAILIN.
8th October, 2013: IMD confirmed cyclone formation and
predicted it as “severe cyclone” and its effects would be felt from
Kalingapatnam in Andhra Pradesh to Paradeep in Odisha, and
that it would probably first strikethe port of Gopalpur in Ganjam
district at about 5 pm on 12 October. The wind speed could touch
10th October, 2013: IMD prediction of a severe cyclone was
converted to a “very severe cyclonic storm” with wind speeds up
to 220 kmph. the US Navy’s Joint Typhoon Warning Centre
predicted it would have wind speeds up to 315 km/h.
12th October, 2013: The “very severe” cyclonic storm had its
landfall at Gopalpur port at about 9 pm with a wind speed of 200
What is GPS?
• The Global Positioning System (GPS) is a space-based
satellite navigation system that provides location and time
information in all weather conditions, anywhere on or
near the Earth where there is an unobstructed line of sight
to four or more GPS satellites.
• A global navigation satellite system consisting of
positioning satellites and their associated ground stations.
The system provides critical capabilities to military, civil
and commercial users around the world.
It is maintained by the US government and is freely
accessible to anyone with a GPS receiver.
Development of GPS
• The GPS project was developed in 1973 to overcome the limitations of previous navigation systems,
integrating ideas from several predecessors, including a number of classified engineering design studies
from the 1960s.
• GPS was created and realized by the U.S. Department of Defense (DoD) and was originally run with
24 satellites. It became fully operational in 1995. Bradford Parkinson, Roger L. Easton, and Ivan A.
Getting are credited with inventing it.
• Advances in technology and new demands on the existing system have now led to efforts to modernize
the GPS system and implement the next generation of GPS III satellites and Next Generation Operational
Control System (OCX).
• Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In
2000, the U.S. Congress authorized the modernization effort, GPS III.
• In addition to GPS, other systems are in use or under development. The Russian Global Navigation
Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete
coverage of the globe until the mid-2000s.
• There are also the planned European Union Galileo positioning system, Chinese Compass navigation
system, and Indian Regional Navigational Satellite System.
BASICs of GPS?
Satellites are placed in Medium Earth Orbit (MEO) at
an altitude of 12,552 miles
Orbital periods of MEO satellites range from 2 - 12
Orbital period of GPS satellites is 12 hours (2
GPS Satellites travel at a speed of 7,000 mph
Orbits are arranged so that at any time, anywhere on
Earth, at least four satellites are visible in the sky
A visual example of a 24 satellite GPS constellation in motion with the
Earth rotating. About nine satellites are visible from any point on the
ground at any one time, ensuring considerable redundancy over the
minimum four satellites needed for a position.
Basic concept of GPS
A GPS receiver calculates its position by precisely
timing the signals sent by GPS satellites high above
Each satellite continually transmits messages that
• the time the message was transmitted
• satellite position at time of message transmission
• Differential time of arrival and triangulation are
the methods used to determine location in a GPS
• Differential Time of Arrival: Differential time
of arrival is the method used to determine how
far each satellite is from a GPS device.
Although each satellite transmits its position
and the time it was at that position, it takes
time for that signal to reach the Earth.
• The receiver contains a very accurate clock,
which can determine the difference in time
between the current time and when the
satellite sent the signal. With this differential
time and the speed of radio waves, the
distance from each of the three satellites can
be determined using the simple formula:
Rate x Time = Distance
Composition of Receivers
• GPS receivers are composed of an antenna,
tuned to the frequencies transmitted by the
satellites, receiver-processors, and a highly
stable clock (often a crystal oscillator).
• They may also include a display for providing
location and speed information to the user.
• A receiver is often described by its number of
channels: this signifies how many satellites it
can monitor simultaneously.
• Originally limited to four or five, this has
progressively increased over the years so that,
as of 2007, receivers typically have between 12
and 20 channels.
Application of GPS
• While originally a military project, GPS is
considered a dual-use technology, meaning it has
significant military and civilian applications.
• GPS has become a widely deployed and useful
tool for commerce, scientific uses, tracking, and
• GPS's accurate time facilitates everyday activities
such as banking, mobile phone operations, and
even the control of power grids by allowing well
synchronized hand-off switching.
• Disaster relief/emergency services: depend upon GPS for location and
• Meteorology-Upper Airs: measure and calculate the atmospheric
pressure, wind speed and direction up to 27 km from the earth's surface
• Fleet Tracking: the use of GPS technology to identify, locate and maintain
contact reports with one or more fleet vehicles in real-time.
• Geofencing: vehicle tracking systems, person tracking systems, and pet
tracking systems use GPS to locate a vehicle, person, or pet. These devices
are attached to the vehicle, person, or the pet collar. The application
provides continuous tracking and mobile or Internet updates should the
target leave a designated area.
• Geotagging: applying location coordinates to digital objects such as
photographs (in exif data) and other documents for purposes such as
creating map overlays with devices like Nikon GP-1
• GPS Aircraft Tracking
• GPS for Mining: the use of RTK GPS has significantly improved several mining
operations such as drilling, shoveling, vehicle tracking, and surveying. RTK GPS
provides centimeter-level positioning accuracy.
• GPS tours: location determines what content to display; for instance, information
about an approaching point of interest.
• Navigation: navigators value digitally precise velocity and orientation
• Phasor measurements: GPS enables highly accurate timestamping of power
system measurements, making it possible to compute phasors.
• Recreation: for example, geocaching, geodashing, GPS drawing and waymarking.
• Robotics: self-navigating, autonomous robots using a GPS sensors, which calculate
latitude, longitude, time, speed, and heading.
• Surveying: surveyors use absolute locations to make maps and determine property
• Tectonics: GPS enables direct fault motion measurement in earthquakes.
• Telematics: GPS technology integrated with computers and mobile
communications technology in automotive navigation systems
Finding the Mystery Location
• Your GPS receiver has been pre-programmed
(by your instructor) with a mystery location.
Now let's explore how the GPS receiver can be
used to navigate to an unknown location.
• Randomly choose three-to-five different
locations on the grounds. These locations
should be fairly distant from each other (at least
500 feet apart). Remember to choose locations
where the GPS receiver will have a good view of
• Proceed to Point No. 1. Record the following
information in the data table below:
• Use the Position Page (graphic compass) to acquire
your current position. Record your latitude and
• Press the GOTO key. The Navigation Page (graphic
highway) will appear with the waypoint field
highlighted. Press the up or down arrow keys to scroll
through the available waypoints until "MYSLOC"
(short for "mystery location") is displayed.
• Press the ENTER key to confirm that you want to
navigate to "MYSLOC". Record the bearing (in
degrees) and distance (in kilometers) to the mystery
• Briefly describe the location.
• Repeat Steps 1-3 until you have visited at least
three different locations on the grounds. Do
not actually go to the mystery location!
Steps to find mystery location
• Using your Field Data for Point No. 1 (latitude,
longitude, and distance), draw Circle 1.
Technique Hint: Use latitude and longitude to
locate Point 1 on the map; use the map scale to
measure the radius of Circle 1; draw the circle.
• Using your Field Data for Point No. 2, draw
• Using your Field Data for Point No. 3, draw
• You would discover that there is one and only
one point where all three circles intersect.
Yield Monitoring Systems
• Yield monitoring systems typically utilize a mass flow sensor for
continuous measuring of the harvested weight of the crop. The sensor
is normally located at the top of the clean grain elevator. As the grain is
conveyed into the grain tank, it strikes the sensor and the amount of
force applied to the sensor represents the recorded yield. While this is
happening, the grain is being tested for moisture to adjust the yield
• At the same time, a sensor is detecting header position to determine
whether yield data should be recorded. Header width is normally
entered manually into the monitor and a GPS, radar, or a wheel rotation
sensor is used to determine travel speed. The data is displayed on a
monitor located in the combine cab and stored on a computer card for
transfer to an office computer for analysis.
• Yield monitors require regular calibration to account for varying
conditions, crops, and test weights. Yield monitoring systems cost
approximately $3,000 to $4,000, excluding the cost of the GPS unit.
GPS Used in Farming?
Field Mapping with GPS and GIS
• GPS technology is used to locate and map regions
of fields, such as high weed, disease, and pest
infestations. Rocks, potholes, power lines, tree
rows, broken drain tile, poorly drained regions,
and other landmarks can also be recorded for
• GPS is used to locate and map soil-sampling
locations, allowing growers to develop contour
maps showing fertility variations throughout
• The various datasets are added as map layers in
geographic information system (GIS) computer
programs. GIS programs are used to analyze and
correlate information between GIS layers.
• GPS technology is used to vary crop inputs
throughout a field based on GIS maps or real-time
sensing of crop conditions. Variable rate technology
requires a GPS receiver, a computer controller, and a
regulated drive mechanism mounted on the
applicator. Crop input equipment, such as planters or
chemical applicators, can be equipped to vary one or
several products simultaneously.
• Variable rate technology (VRT) is used to vary
fertilizer, seed, herbicide, fungicide, and insecticide
rates and for adjusting irrigation applications. The
cost of all of the components necessary for variable
rate application of several products is approximately
$15,000, not including the cost of the GPS receiver.
Technology capable of varying just one product costs
PRECISION CROP INPUT APPLICATIONS
DRAWBACK of GPS
• The drawback to current GPS units is
that they cannot track positions inside
of buildings or other places that shield
signals coming from satellites.