SF11 Laser altimeter Product manual The definitive laser altimeter for fixed wing or multirotor aircraft. Ideal for automated landings, precision hovering and terrain following.
SF11 Laser altimeter Product manual Table of contents Product ordering codes ..................................................................................................................................... 2 1. Overview .................................................................................................................................................. 3 2. Specifications of the SF11 ............................................................................................................
SF11 Laser altimeter Product manual 1. Overview The light-weight SF11 laser altimeter is an essential addition to any unmanned aircraft that needs fast, accurate and reliable AGL altitude measurements. The SF11 laser altimeter makes accurate distance measurements to solid surfaces up to an altitude of 120 meters and water up to 40 meters.
SF11 Laser altimeter Product manual 2. Specifications of the SF11 SF11/B (50 m) SF11/C (120 m) Range 0.2 … 50 meters (natural targets) 0.2 … 120 meters (natural targets), 2 ... 40 meters (moving water) Resolution 1 centimeter 1 centimeter Update rate 40 readings per second 20 readings per second Accuracy ±0.1 meter (70% reflective target @ 20°C) ±0.1 meter (70% reflective target @ 20°C) Power supply voltage 5.0 V ± 0.5 V DC 5.0 V ± 0.
SF11 Laser altimeter Product manual 3. Quick start guide 1. CAUTION - The SF11 laser altimeter contains a laser and should never be aimed at a person or an animal. Do not look at the beam directly with optical instruments. 2. Download LightWare Terminal software from www.lightware.co.za > Library > Documents > Software onto your PC. Open the installer package and follow the installation instructions. Everything needed for communicating with the SF11 will automatically be installed. 3.
SF11 Laser altimeter Product manual 1. Making connections to the SF11 The SF11 gets power from either a regulated +5 V DC supply on the main connector or via the USB port when it is connected to a PC. There are analog, serial and I2C interfaces on the main connector and either one or a combination of interfaces may be connected to a host controller. The built-in micro USB port can be used to input settings and to test the performance of the SF11.
SF11 Laser altimeter Product manual Settings can be changed by pressing the key to access the menu and then selecting the menu item that needs changing. Pressing the key again restarts the measuring process. If no settings are entered then the SF11 automatically restarts after two minutes. More details of the menu items are discussed in the “Menu options” section below.
SF11 Laser altimeter Product manual I2C interface The I2C interface on the main connector can be used to output a value that represents the altitude in centimetres. This interface operates in “slave” mode and uses 3.3 V logic levels. The I2C address can be set through the USB menu system. The host controller acts as the I2C “master” and sends the address to the SF11 as an 8 bit value (7 address bits plus 1 read/write bit). The SF11 then returns the altitude as a 16 bit integer.
SF11 Laser altimeter Product manual 5. Menu options The SF11 can be connected through the on-board USB port to a Terminal emulation program running on a PC. The LightWare Terminal software is available for download from www.lightware.co.za. Once the USB connection is made, the Terminal window displays the distance reading from the SF11. The distance, analog voltage or alarm status and the signal strength are displayed continually in the Terminal window.
SF11 Laser altimeter Product manual c: Measuring mode (long range | quick response) Menu item enables optimisation of the measuring mode to suit applications requiring either long range measurements or a quick response when signals go out of range. The maximum measuring range remains the same and in many applications there will be little difference in the performance. However, long range mode is recommended when measuring over water or continually operating at an altitude above 50 meters.
SF11 Laser altimeter Product manual i: Linear analog output (0.00 m to 25.00 m = 0.00 V to 2.048 V | 0.00 m to 25.00 m = 2.048 V to 0.00 V) Menu item is used to select either an analog voltage or a digital alarm output. There are four selections, two for the analog voltage and two for the alarm. This section describes the analog voltage output. This value may also be changed using the serial port and I2C command set. The two analog output selections determine the polarity of the analog voltage.
SF11 Laser altimeter Product manual k: Analog voltage range (0.00 V … 2.048 V or 0.00 V … 3.30 V) Select the maximum voltage of the analog output using menu item . This provides compatibility with different ADC systems on the host controller. The analog voltage range may also be changed using the serial port and I2C command set. Item HMI Analog voltage range menu item 0.00 V ... 2.048 V Type read write Serial ?OV ?OV 2.048 #OV,0 #OV,0 0 I2C .write(14) .
SF11 Laser altimeter Product manual j: Alarm switching distance (1.00 m … 120.00 m) The distance at which the alarm output switches can be set by selecting menu item . This value may also be changed using the serial port and I2C command set. Item HMI Analog range / alarm set point menu item 56.78 m Type Serial ?OD ?OD 56.78 #OD,56.78 #OD,56.78 56.78 read write I2C .write(12) .read(a,b) distance range = (a*256+b)/100 .
SF11 Laser altimeter Product manual p: Confirm lost signal (0.0 ... 120.0 seconds) Menu item
is used to set how long a lost signal is permitted before the out of range condition selected in menu item n: is applied. When operating close to the measuring limit of of the SF11 or over water, signals may be lost intermittently. Rather than jumping between the measured altitude and the out of range condition, this menu item can be set to hold the last valid altitude for the entered time.
SF11 Laser altimeter Product manual 6. Instructions for safe use The SF11 is a laser based altimeter that emits ionizing laser radiation. The level of the laser emission is Class 1M which indicates that the laser beam is safe to look at with the unaided eye but must not be viewed using binoculars or other optical devices at a distance of less than 15 meters. Notwithstanding the safety rating, avoid looking into the beam and switch the unit off when working in the area.
SF11 Laser altimeter Product manual Appendix A :: Dimensions Figure 14 :: Dimension drawings of the SF11 Appendix B :: Main cable type 1, 35 cm SF11 Laser altimeter - Product manual - Revision 9 | 16 of 20 | © LightWare Optoelectronics (Pty) Ltd, 2019 | www.lightware.co.
SF11 Laser altimeter Product manual Appendix C :: Connecting to Pixhawk Autopilot using “serial 4” Appendix D :: Electromagnetic interference (EMI) graphs The SF11 family has been tested for radio frequency interference in accordance with MIL-STD-451C. The results are well within the required limits so that neither direct radiation nor secondary radiation from wiring should cause interference to on-board systems such as GPS and optical flow. 1.
SF11 Laser altimeter Product manual 2. 14 kHz to 1 GHz - broadband 3. 1 GHz to 10 GHz - narrowband SF11 Laser altimeter - Product manual - Revision 9 | 18 of 20 | © LightWare Optoelectronics (Pty) Ltd, 2019 | www.lightware.co.
SF11 Laser altimeter Product manual Appendix E :: Command set Item Model no. and firmware revision Distance in meters Analog output voltage Signal strength in % HMI menu heading SF11/C V7 Firmware: V1.0.0 measuring screen 98.67 m Type read only read only legacy support measuring screen 1.567 V measuring screen 100% read only read only read Zero datum offset in meters Measuring mode Serial port output type Analog output mode menu item 0.56 m write write read menu item on demand ...
SF11 Laser altimeter Product manual Revision history Version Date Author Comments Rev 9 2019/02/26 TLP Add a note to the Serial interface section: “The default baud rate is 115200 bps” (page 7). Rev 8 2018/05/29 TLP Included the SF11/B model (page 2, 4). Updated all references to the analog voltage range option “0.00 V … 2.56 V” to “0.00 V … 2.048 V”. This change is applicable to SF11/B firmware revision 1.0.0, SN: S11-01500 onwards and SF11/C firmware revision 1.0.
