dji Phantom 2 Vision + User manual

©2013-2014 DJI. All Rights Reserved.1 |
PHANTOM 2 User Manual V1.2
For PHANTOM 2 Flight Controller Firmware version V3.08
& PHANTOM 2 Assistant version V3.4
& PHANTOM RC Assistant version V1.1
2014.10
Congratulations on purchasing your new DJI product. Please thoroughly read the entire contents of this manual to
fully use and understand the product.
It is advised that you regularly check the PHANTOM 2’s product page at www.dji.com which is updated on a
regular basis. This will provide services such as product information, technical updates and manual corrections. Due
to any unforeseen changes or product upgrades, the information contained within this manual is subject to change
without notice.
DJI and PHANTOM 2 are registered trademarks of DJI. Names of product, brand, etc., appearing in this manual are
trademarks or registered trademarks of their respective owner companies. This product and manual are copy
righted by DJI with all rights reserved.
If you have any questions or concerns regarding your product, please contact your dealer or DJI Customer Service.

©2013-2014 DJI. All Rights Reserved. 2 |
Content
CONTENT........................................................................................................................2
IN THE BOX .....................................................................................................................4
LEGEND ..........................................................................................................................4
1. PHANTOM 2 AIRCRAFT ...............................................................................................5
1.1 BUILT-IN FLIGHT CONTROL SYSTEM INSTRUCTIONS..................................................................5
1.2 CONNECTIONS WITH OTHER DJI PRODUCTS...........................................................................5
Important Notes of Using with Other DJI Products ........................................................6
Connections with Other DJI Products .............................................................................7
1.3 LED FLIGHT INDICATORS DESCRIPTION ...............................................................................11
1.4 NOTES FOR PHANTOM 2USING WITH OTHER DJI PRODUCTS ................................................12
2 PROPELLERS...............................................................................................................13
2.1 ASSEMBLY.....................................................................................................................13
2.2 DISASSEMBLY ................................................................................................................13
2.3 NOTES .........................................................................................................................13
3 REMOTE CONTROL ....................................................................................................14
3.1 POWER ON THE REMOTE CONTROL....................................................................................14
3.2 REMOTE CONTROL LED INDICATOR STATUS .........................................................................15
3.2.1 Remote Control Power LED Indicator Status .......................................................15
3.2.2 Remote Control Battery Level Indicator Status....................................................15
3.3 ANTENNA ORIENTATION ..................................................................................................16
3.4 REMOTE CONTROL OPERATION .........................................................................................16
3.5 LINKING THE REMOTE CONTROL &BUILT-IN RECEIVER...........................................................18
4 INTELLIGENT BATTERY ...............................................................................................19
4.1 CHARGING PROCEDURES..................................................................................................19
4.2 INSTALL THE BATTERY ......................................................................................................20
4.3 BATTERY USAGE.............................................................................................................20
4.4 DESCRIPTION OF THE BATTERY LEVEL INDICATOR...................................................................21
4.5 CORRECT BATTERY USAGE NOTES ......................................................................................22
5 CALIBRATING THE COMPASS......................................................................................23

©2013-2014 DJI. All Rights Reserved.3 |
5.1 CALIBRATION WARNINGS .................................................................................................23
5.2 CALIBRATION PROCEDURES ..............................................................................................23
5.3WHEN RECALIBRATION IS REQUIRED...................................................................................23
6 FLIGHT .......................................................................................................................24
6.1 FLYING ENVIRONMENT REQUIREMENTS ..............................................................................24
6.2 STARTING THE MOTORS ...................................................................................................24
6.3 TAKEOFF/LANDING PROCEDURES.......................................................................................24
6.4 FAILSAFE FUNCTION........................................................................................................25
6.5 LOW BATTERY CAPACITY WARNING FUNCTION.....................................................................27
6.6 FLIGHT LIMITS FUNCTION.................................................................................................27
Max Height & Radius Limits .........................................................................................27
6.7 FLIGHT LIMITS OF SPECIAL AREAS ......................................................................................28
6.8 CONDITIONS OF FLIGHT LIMITS .........................................................................................30
Disclaimer.....................................................................................................................30
7 ASSISTANT INSTALLATION AND CONFIGURATION ......................................................31
7.1 INSTALLING DRIVER AND PHANTOM 2ASSISTANT...............................................................31
7.2 USING THE PHANTOM 2ASSISTANT ON A PC ....................................................................32
7.3 FIRMWARE UPGRADE OF PHANTOM 2 .............................................................................33
7.4 PHANTOM RC ASSISTANT DESCRIPTION ...........................................................................33
8 APPENDIX ..................................................................................................................35
8.1 SPECIFICATIONS..............................................................................................................35
8.2 LED FLIGHT INDICATORS DESCRIPTION ...............................................................................35

©2013-2014 DJI. All Rights Reserved.4 |
In the Box
PHANTOM 2
Remote Control-2.4GHz
Propeller Pair
Intelligent Battery
Charger
Plug Set
Screwdriver
Assistant Wrench
Cables
Micro-USB Cable
Screws
Accessories Box
Legend
Forbidden(Important)
Caution
Tip
Reference

©2013-2014 DJI. All Rights Reserved.5 |
1. PHANTOM 2 Aircraft
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[10]
[11]
[9]
Figure 1-1 Figure 1-2
[1]Propeller [2]Motor [3]Front Side [4]Front LEDs [5]Micro-USB Port [6]Landing Gear [7]Receiver
Antenna [8]CAN-Bus Connector [9]LED Flight Indicators [10]DJI Intelligent Battery [11]Compass
1.1 Built-in Flight Control System Instructions
The built-in flight control system is used to control the entire aircraft’s functions in flight such as Pitch (forwards
and backwards), Roll (left and right), Elevator (up and down) and Yaw (turn left or right). The flight controller
contains the MC (Main Controller), IMU, GPS, compass, receiver.
The IMU (Inertial Measurement Unit) has a built-in inertial sensor and a barometric altimeter that measures both
attitude and altitude. The compass reads geomagnetic information which assists the GPS (Global Position System)
to accurately calculate the aircrafts position and height in order to lock the aircraft in a stable hover. The receiver is
used to communicate with the remote control and the MC acts as the brains of the complete flight control system
connecting and controlling all the modules together.
The PHANTOM 2 can be configured in the Assistant, by choosing Naza-M mode or Phantom 2 mode.
This manual is for Phantom 2 mode. Please refer to the Naza-M V2 Quick Start Manual for more
information.
1.2 Connections with Other DJI Products
PHANTOM 2 is compatible with other DJI products, including ZENMUSE H3-2D and H3-3D gimbal，iOSD mini，
iOSD Mark II. Below are connections for these products and wireless video transmission module.
Compass
Gimbal Mounting Position
Mount the H3-2D/H3-3D
gimbal using 4 screws.
CAN-Bus Connector
Video Cable
To the iOSD module or wireless
video transmission module.
8-Pin Cable
To the G8 port on
the H3-2D/H3-3D
gimbal.
5-Pin Cable
To the compass.
Figure 1-3

©2013-2014 DJI. All Rights Reserved.6 |
Important Notes of Using with Other DJI Products
（1）The video cable can provide power for the wireless video transmission module with a battery voltage
(11.1V~12.6V) and a maximum current 2A.
（2）Make sure the working current of the wireless video transmission module you connect can work with an
operational voltage between 11.1V~12.6V and the total working current of the iOSD and wireless video
transmission module is under 2A, as an overcurrent will damage the central board’s components. If the
total current exceeds 2A, please be sure to provide power supplied from a separate power source for the
wireless video transmission module.
（3）PHANTOM 2 uses a 2.4GHz RC system. To avoid communication interference, it’s not recommended to
use other 2.4GHz devices (including 2.4G Wi-Fi or 2.4G wireless video transmission module) except the
2.4G Bluetooth and 2.4G Datalink.
（4）Be sure to keep the wireless video transmission module and other communicating devices away from the
compass during installation and connection to avoid interference.
（5）To improve the compatibility with ZENMUSE gimbals, the latest factory deliveries of PHANTOM 2 has
updated to the Version 2 shown below. H3-2D/H3-3D gimbal can be directly installed for the Version 2
while for Version 1, a H3-3D adapter kit (coming soon) is required to install the H3-3D gimbal.
Version 1
Gimbal Mounting
Position
Version 2
Gimbal Mounting
Position
Figure 1-4
（6）When using the H3-3D gimbal, please connect the 8-Pin cable of PHANTOM 2 to the G8 port of H3-3D
shown below.
Figure 1-5

©2013-2014 DJI. All Rights Reserved.7 |
Connections with Other DJI Products
（1）Connecting the H3-2D and H3-3D gimbal and wireless video transmission module, the figure below uses
H3-2D as an example.
ZENMUSE
H3-2D
Compass
VIDEO
VIDEO GND
Batt+
Batt-
Wireless
video
transmission
module
Transmitter
Description of the Video Cable
(sequence by color)
VIDEO GND
VBat+
VIDEO
GND
Figure 1-6
（2）Connecting the H3-2D and H3-3D gimbal, iOSD mini and wireless video transmission module, the figure
below uses H3-2D as an example.
ZENMUSE
H3-2D
Compass
CAN-Bus
Connector
VIDEO GND
VBat+
GND
VIDEO GND
VIDEO
Batt+
Batt- VIDEO
DJI
Description of the Video Cable
(sequence by color)
Wireless
video
transmission
module
Transmitter
Figure 1-7

©2013-2014 DJI. All Rights Reserved.8 |
（3）Connecting the H3-2D and H3-3D gimbal, iOSD mini and DJI specified wireless video transmission module
AVL58, the figure below uses H3-2D as an example.
ZENMUSE
H3-2D
Compass
DJI
DJI specified
wireless
video
transmission
module
AVL58
Transmitter
CAN-Bus
connector
VIDEO GND
VBat+
GND
VIDEO
Description of the Video Cable
(sequence by color)
Figure 1-8
We recommend connecting the VBat+ port of the video cable to the two BATT+ ports of the AVL58
simultaneously. The same is true of the GND port of the video cable and two BATT- ports.
（4）Connecting the H3-2D and H3-3D gimbal, iOSD Mark II and wireless video transmission module, the figure
below uses H3-2D as an example.

©2013-2014 DJI. All Rights Reserved.9 |
ZENMUSE
H3-2D
VBat+
GND
VIDEO
DJI
VIDEO GND
Wireless video transmission
module Transmitter specified by
DJI(AVL58)
OR
Other wireless video transmission
module Transmitter
CAN-Bus
Connector Compass
Description of the Video Cable
(sequence by color)
Figure 1-9
The diagram below illustrates the conneciton between the iOSD Mark II and the wireless video transmission module.
iOSD Mark II
Other wireless video
transmission module
Transmitter
VIDEO GND
VIDEO
Batt-BATT-
BATT-
BATT+
BATT+
UART
UART
AV-OUT
AV-GND
Batt-
Batt+
Batt+
Wireless video
transmission
module
AVL58 Transmitter
specified by DJI
iOSD Mark II
AV-OUT
AV-GND
BATT-
BATT-
BATT+
BATT+
UART
UART
Use the 8-Pin cable in the iOSD Mark II package when connecting to the DJI specified wireless video
transmission module AVL58.
（5）Using the iPad Ground Station

©2013-2014 DJI. All Rights Reserved.10 |
iPad Ground
Station
iPad Ground
Station
+-
3S-6S
Battery
3S-6S
Battery
Air End
Ground End
Figure 1-10
Connect the Air End of 2.4G Bluetooth Datalink to a spared CAN-Bus port of iOSD if an iOSD is used.
（6）Using the PC Ground Station
Air End
Ground End
PC Ground
Station
Figure 1-11

©2013-2014 DJI. All Rights Reserved.11 |
1.3 LED Flight Indicators Description
1. LED flight indicators are used to show the aircraft’s current status. Once powered on, the indicators will light
up.
LED flight
indicators
Aircraft in Normal status
Descriptions
Power On Self-Test
Warming Up & Aircraft cannot take off during warming up
Ready to Fly
Ready to Fly (non-GPS)
Aircraft in abnormal status
Warnings and errors
Remote Control Signal Lost
1st Level Low Battery Capacity Warning
2nd Level Low Battery Capacity Warning
Not Stationary or Sensor Bias is too big
Errors & Aircraft cannot fly.
Compass data abnormal because of ferro-magnetic interference or
the compass needs calibration.
（1）The LED indicators diagram above are for Phantom 2 mode. In Naza-M mode, LED indicators
will work according to the Naza-M flight control system.
（2）Connect to the PHANTOM 2 Assistant for detailed information about warnings and errors.
2. The front LEDs are for indicating where the nose of the aircraft is. They light up solid red only after the motors
have spooled up.
The front
LEDs

©2013-2014 DJI. All Rights Reserved.12 |
1.4 Notes for PHANTOM 2 using with other DJI products
Before using PHANTOM 2 with other DJI products, users should connecting the products correctly and upgrade
the firmware as requirements below .
Items to upgrade
Firmware versions required
Assistant for upgrading
Assistant version
P330CB (built-in
central board)
V1.0.1.19 or above
PHANTOM 2
V1.08 or above
Zenmuse H3-2D
CMU V1.0，IMU V1.6 or above
PHANTOM 2
V1.08 or above
iOSD Mark II
V3.01 or above
iOSD
V4.0 or above
iOSD mini
V1.06 or above
iOSD
V4.0 or above
*The iOSD Assistant is applied to both iOSD Mark II and iOSD mini.

©2013-2014 DJI. All Rights Reserved.13 |
2 Propellers
PHANTOM 2 uses the original 9-inch propellers which are classified by the color of each central nut. Damaged
propellers should be replaced by purchasing new ones if necessary.
Propellers
Grey Nut (9450)
Black Nut (9450 R)
Diagram
Assembly Location
Attach to the motor thread that does
not have a black dot.
Attach to the motor thread that has a
black dot.
Fastening/Un-fastening
Instructions
Lock: Tighten the propeller in this direction.
Unlock: Remove the propeller in this direction.
2.1 Assembly
1. （Figure 2-1）Remove the four warning cards from the motors after you’ve read them.
2. （Figure 2-2）Prepare the two grey nut propellers and two black nut propellers. Make sure to match the
black nut propellers with the correctly marked black dot motors. Tighten the propellers according to the
fastening instructions.
Figure 2-1 Figure 2-2 Figure2-3
2.2 Disassembly
（Figure 2-3）Keep the motor deadlocked in place with the assistant wrench (or one hand) and remove the
propeller according to the un-fastening instructions.
2.3 Notes
1. Propellers are self tightening during flight. DO NOT use any thread locker on the threads.
2. Make sure to match the propeller nut colors with the corresponding motors.
3. It is advised to wear protective gloves during propeller assembly and removal.
4. Check that the propellers and motors are installed correctly and firmly before every flight.
5. Check that all propellers are in good condition before flight. DO NOT use any ageing, chipped, or broken
propellers.
6. To avoid injury, STAND CLEAR of and DO NOT touch the propellers or motors when they are spinning.
7. ONLY use original DJI propellers for a better and safer flight experience.

©2013-2014 DJI. All Rights Reserved.14 |
3 Remote Control
The PHANTOM 2 remote control can be configured in the PHANTOM RC Assistant. The sticks mode is Mode 2 on
delivery.
For upgraded remote control (models: NDJ6 or NRC900), select “Upgrade Version” in Phantom Assistant.
For basic remote control (models: DJ6 or RC900), select “Basic Version” in Phantom Assistant.
[1]
[2]
[5] [4]
[9]
[10]
J2
J1
J3
J4 [7]
[8]
[6]
[3]
[11]
[12]
[13]
[14]
Figure 3-1 Figure 3-2
[1]Antenna [2]Carrying Handle [3]Left Dial [4]3-Position Switch S1 [5]3-Position Switch S2 [6]Joystick1(J1;J2)
[7]Joystick2(J3;J4) [8]Neck Strap Attachment [9]Power Switch [10]Power Indicator
[11]Battery Level Indicators LED1/LED2/LED3/LED4 (from left to right) [12]Trainer Port
[13]Battery Charge & RC Assistant Port (micro-USB port) [14] Potentiometer
3.1 Power on the Remote Control
1. Set the S1 and S2 switches to the upper most position and ensure both joysticks are at
the mid-point position. Then toggle on the power switch.
2. Push the power switch to the right to power on the remote control. If the power LED
indicator is solid on, the remote control is functioning normally. The battery level
indicators display the current battery level.
1. Please make sure the battery level of remote control is enough. If the low voltage warning alert
sounds (refer to <Remote Control Power LED Indicator Status>), please recharge the battery as soon as
possible.
2. Charge the remote control’s battery by using the included micro-USB cable. Using the incorrect
type of charging cable may cause damage.
3. Turn off the remote control before charging. The power LED indicator will display solid red when
charging is in progress. The LED indicators will display solid green when the battery is fully charged.

©2013-2014 DJI. All Rights Reserved.15 |
3.2 Remote Control LED Indicator Status
3.2.1 Remote Control Power LED Indicator Status
Power LED Indicator
Sound
Remote Control Status
None
Functioning normally.
None
Charging( remote control is powered off)
None
Remote control joysticks calibration error, need to be re-calibrate.
BB---BB---BB
Low voltage (from 3.5V-3.53V), recharge the remote control.
B-B-B……
Critical low voltage (from 3.45V-3.5V). Recharge the remote control
immediately.
B--B--B……
Alert will sound after 15 minutes of inactivity. It will stop once you
start using the remote control.
The remote control will power off automatically when battery voltage drops below 3.45V. Land and
recharge the battery as soon as possible when the low voltage alert occurs to avoid loss of control
during flight.
3.2.2 Remote Control Battery Level Indicator Status
The battery level indicators will show the current battery level during both the discharging process. The following is
a description of the indicators.
: The LED is solid on : The LED will blink regularly
: The LED is light off
Discharging process
LED1
LED2
LED3
LED4
Current battery level
75%~100%
50%~75%
25%~50%
12.5%~25%
0%~12.5%
<0%

©2013-2014 DJI. All Rights Reserved.16 |
3.3 Antenna Orientation
The remote control’s antenna should point skywards without obstructions for maximum communication range
during flight.
Figure 3-3
3.4 Remote Control Operation
The operations of remote control are based on mode 2 stick configuration.
Definitions
The ‘stick neutral’ positions and ‘stick released’ mean the control sticks of the remote control are placed at
the central position.
To ‘move the stick’means that the stick of remote control is pushed away from the central position.
Slide Lever is used for the pitch control of the H3-2D and H3-3D gimbal.
Remote
Control
(Mode 2)
Aircraft
（nose direction）
Operation details
The throttle stick controls aircraft altitude/elevation.
Push the stick up and the aircraft will rise.
Pull the stick down and the aircraft will descend.
The aircraft will automatically hover and hold its
altitude if the sticks are centered.
Push the throttle stick above the centered (mid-point)
position to make the aircraft take off. When flying, we
suggest that you push the throttle stick slowly to
prevent the aircraft from sudden and unexpected
elevation changes.

©2013-2014 DJI. All Rights Reserved.17 |
The yaw stick controls the aircraft rudder.
Push the stick left and the aircraft will rotate counter
clock-wise.
Push the stick right and the aircraft will rotate
clock-wise. If the stick is centered, the aircraft will
remain facing the same direction.
The yaw stick controls the rotating angular velocity of
the aircraft. Pushing the stick further away from center
results in a faster aircraft rotation velocity.
The pitch stick controls the aircraft’s front & back tilt.
Push the stick up and the aircraft will tilt and fly
forward.
Pull the stick down and the aircraft will tilt and fly
backward. The aircraft will keep level and straight if the
stick is centered.
Pushing or pulling the stick further away from center
will result in a larger tilt angle (maximum of is 35˚) and
faster flight velocity.
The roll stick controls the aircraft’s left & right tilt.
Push the stick left and the aircraft will tilt and fly left.
Push the stick right and the aircraft will tilt and fly right.
The aircraft will keep level and straight if the stick is
centered.
Pushing the stick further away from center will result in
a larger tilt angle (maximum of 35˚) and faster flight
velocity.
Position-1 Position-2 Position-3
S1 is for compass calibration. Toggle the S1 switch from
position-1 to position-3 and back to position-1 at least 5
times, which will force the aircraft to enter into
compass calibration mode.
Users can configure position 3(bottom position) of the
S1 switch to trigger the Failsafe in the Assistant.
OFF Course Lock Home
point Lock
S2 is the IOC mode switch. IOC (Intelligent
Orientation Control) function can be enabled in the
Assistant when in Naza-M mode. Only use the IOC
function after you are familiar with flying.

©2013-2014 DJI. All Rights Reserved.18 |
The left dial controls the pitch of the H3-2D and H3-3D
gimbal. The position of left dial determines the pitch
angle relative to the horizontal level.
Turn the left dial to the right to make the gimbal pitch
up.
Turn the left dial to the left to make the gimbal pitch
down.
The gimbal will keep its current position if the dial is
static.
（1）For ‘Ready to Fly’ the aircraft will hover when all sticks are released.
（2）For ‘Ready to Fly (non-GPS)’ the aircraft will only keep the altitude when all sticks are released.
3.5 Linking the Remote Control & Built-in Receiver
PHANTOM 2 has a built-in receiver, the link button and indicator located on the bottom of the aircraft as illustrated
in the Figure 3-4.
The link between the remote control and aircraft is already established for you so you can initially skip this
procedure. If you ever replace the remote control, re-establishing the link is required.
Link button &
Link indicator
Figure 3-4
Linking procedures
1. Power on the PHANTOM 2.
2. Turn on the remote control and place it 0.5m~1m away from the aircraft.
3. Push the link button with a thin object and hold it until the Link indicator blinks red, then release it.
4. When the Link indicator turns solid green, the link between the remote control and the built-in receiver has
been successfully established.
Link Indicator
Status
The remote control is turned off and there is no 2.4GHz signal around, please turn on
the remote control.
The receiver is ready for linking.
There is 2.4GHz signal around but the remote control is not linked with the receiver,

©2013-2014 DJI. All Rights Reserved.19 |
please carry out the linking procedures.
The remote control is linked with the receiver successfully.
4 Intelligent Battery
The intelligent battery is specially designed for the PHANTOM 2, with a battery capacity of 5200mAh, voltage of
11.1V and charge-discharge management functionality. The battery should only be charged with the DJI charger.
Intelligent Battery Charger
DJI Intelligent Battery Functions
（1）Balance Charging
Automatically balance the voltage of each battery cell during charging.
（2）Capacity Display
Display the current battery level.
（3）Communicating
The main controller communicates with the battery via communication ports
for battery voltage, capacity, current and other information.
（4）Overcharging Protection
Charging stops automatically when the battery voltage reaches 12.8V to
prevent overcharging damage.
（5）Over Discharging
Protection
Discharging stops automatically when the battery voltage reaches 8.4V to
prevent over discharging damage.
（6）Short Circuit Protection
Automatically cuts off the power supply when a short circuit is detected.
（7）Sleep Protection
The battery will enter sleep mode after 10 minutes of inactivity to save
power. The static current is 10nA in sleep mode when the battery is
powered on without connecting to other devices.
（8）Charging Temperature
Detection
The battery will charge only when its temperature is within 0℃~55℃. If the
battery temperature is out of this range, the battery will stop charging.
（1）Before use, please read and follow the user manual, disclaimer, and the warnings on the battery.
Users take full responsibility for all operations and usage.
（2）The battery should only be charged with the charger provided by DJI. DJI does not take any
responsibility for operation of any charger from a third party.
4.1 Charging Procedures
1. Connect the charger to a wall socket (Use the plug set if necessary).
2. Connect the battery to the charger. If the current capacity of the battery is over 75%, you should power on
the battery to begin charging.
3. The Battery Level indicators display current capacity level as the battery charges. Please refer to battery

©2013-2014 DJI. All Rights Reserved.20 |
level indicator description for details.
4. The battery is fully charged when the Battery Level indicator lights are off. Please disconnect the charger
and battery when the charging is completed.
Wall Socket
4.2 Install the Battery
Push the battery into the battery compartment correctly as the following diagram shows. Make sure to push the
battery into the compartment until you hear a ‘click’ sound.
Figure 4-1
An incorrectly inserted battery may cause one of the following to occur: (1) Bad contact. (2) Unavailable
battery information. (3) Unsafe for flight. (4) Unable to take off.
4.3 Battery Usage
Figure 4-2
(1) Checking the battery level: When the battery is powered off; pressing the battery power button once will
indicate the current battery level. Refer to < Battery Level Indicator Description> for details.
(2) Powering on: When the battery is powered off; press the battery power button once and then press and hold for
2 seconds to turn on the intelligent battery.
(3) Powering off: When the battery is powered on; press the battery power button once and then press and hold for
2 seconds to turn off the intelligent battery.
LED3
LED4
Battery Power Button
(Built-in Battery Power Indicator)
LED2
LED1
Battery Level Indicator