This document summarizes and compares digital levels and automatic levels. Digital levels eliminate the need to read a staff by using a barcoded staff and built-in software to automatically record readings. They provide precise measurements and calculations. Automatic levels make leveling easier through an optical compensator that keeps the line of sight horizontal. Both types of levels are used for leveling surveys but digital levels provide additional automated functions and data collection capabilities.

1. SURVEYING
ASSIGNMENT
TOPIC: DIGITAL LEVEL
AUTO LEVEL
SUBMITTED BY
ZUBDA SAJDA
BARCH/15047/14
BIT PATNA

2. DIGITAL LEVELS
This is the latest form of the level, which can
eliminates the need to read the staff and record
readings. It is also known as Electronic level. It is
very powerful and accurate for many uses. Both
electronic and optical readings are possible.
Digital levels are used for all types of leveling
operations in precise level and in tachometry.
It uses a compensator mechanism, it is helpful
to take care of small tilt in the axis.
.

3. COMPENSATOR
•It consists of two mirrors or prisms, fixed to the barrel of the
telescope.
•Another prism or mirror is suspended by two non-magnetic
wires and moves by the action of gravity when the telescope
is tilted.
•A ray of light gets reflected from the fixed and suspended
mirror or prisms and always remains horizontal.
•A damping device with counter weight is provided to
prevent excessive oscillations of the system.

4. •The mechanism also consists of a circular bubble, this is
required to activate the compensator when the telescope is
not perfectly level.
Fig:
a)components of digital
level instrument
b)Compensator
mechanism
(a)
(b)

5. Digital levels are used in conjunction with a special bar
coded staff. Software is built into the level to read the staff
and send information to the digital display unit.
Once the bar-coded staff is sighted, a button is pressed
to take the reading. The reading is taken, stored and
displayed on a console screen in a matter of seconds.
The built in software programs enable distances and
elevations to be calculated and displayed.

6. The instrument can be powered by normal batteries or
rechargeable battery pack with a working time of 10 hours.
The level is useful in topographic surveys, tunnel surveys
and mine surveying.
Examples of digital level:
DL 100 Digital Level
Sokkia’s SDL 30 Digital Level
Other facilities can also be added by the manufacturer.
The data which is obtained can also be fed to a computer
through an RS-232 cable for future processing.

7. The operating functions and software of digital level
include following :-
Horizontal distance measurement to staff for
contouring.
Height determination of intermediate points.
Calculation of difference in elevation.
Selectable minimum unit for reading.
Alphanumeric input of function.

8. AUTOMATIC (auto) LEVEL
The automatic level is very easy to operate. It
ensures accurate leveling. It is simpler and
convenient to use .
Typical parts of an auto level
The auto level has the following components in three
different views:
1.Right side view
The leveling head is a very important component in this
view. It has three parts
a. A circular plate, or tribrach, which carries a spirit level
and the instrument .
b. Three leveling screws or foot screws.
c. A foot plate or trivet attached to the tripod head .

9. 2.Top view
The view shows the following parts:
•Spherical level, practically a sprit level where the bubble
must be within the circle to give a horizontal line of sight.
•The instrument can be rotated by hand using “gun sight” at
the telescope.
•The object focusing screw to focus the staff or other object
image properly .
• Tangent screw on each side help in finer adjustment for
focusing the image of the object.

10. 3.Left-side view
A mirror fitted over the spherical level is the only new
component in this view.
In an automatic level, the line of sight is automatically made
perpendicular to the vertical axis by an optical system called
compensator.
A compensator is an optical unit consisting of prisms placed
in the optical path between the eye piece and the objective.
It consists of two mirrors or prisms, fixed to the barrel of
the telescope.

11. Fig: auto levels
a)Mechanism of
compensator
b)Components of auto level
instrument
c)A typical auto level
instrument
(a)
(b)
(c)

12. Another prism or mirror is suspended by two non-
magnetic wires and moves by the action of gravity when
the telescope is tilted.
A ray of light gets reflected from the fixed and suspended
mirror or prisms and always remains horizontal.
A damping device with counter weight is provided to
prevent excessive oscillations of the system.
The mechanism also consists of a circular bubble, this is
required to activate the compensator when the telescope is
not perfectly level.

13. The automatic level is vey easy to operate.
Once the telescope is approximately level, the
compensator is active and we have to take readings on the
staff by keeping it at different points.
The adjustment of the compensator is a highly specialized
job and should be got done from the manufacturer. The
compensator are generally quite robust, and they rarely go
out of adjustment.
Example of automatic level:
NI-NA 20 Automatic level
The instrument is fully scaled and can be used even in
rain, dust, snow, cold or heat.

14. Advantages of auto level:-
•It is much simpler and convenient to use.
•The leveling work is done quickly and economically.
•It gives an erect image. Therefore, the staff reading is
taken easily.
•There is no error due to inaccurate centering of the
bubble.

15. REFERENCE:-
TEXTBOOK
1.SURVEYING (VOLUME-II) BY
DR. K.R ARORA
2. FUNDAMENTALS OF SURVEYING
AND LEVELLING BY
R. SUBRAMANIAM

16. THANK YOU