Rotator Mk1 - SARCNET

• 20W solar panel
• 10A MPPT Solar Charge Controller
• 12V 7AH SLA Battery
• 12V-USB Power Converter
• Raspberry Pi, running Gpredict and Hamlib rotctld/rigctld
• LCD Monitor, Mouse and Keyboard
• Dual-band Arrow antenna
• Yaesu FT-817 transceiver
• Our Mini Satellite-Antenna Rotator

• Description
• Parts List (Mk1a Version)
• Parts List (Mk1b Version)
• Parts List (Mk1c Version)
• Project Status
• Latest Software
• Status reported by builders
• Problems experienced by some builders
• In the news
• Hardware Build Notes
• Mechanical
• Sensor Orientation
• Electrical (Mk1a)
• Electrical (Mk1b)
• Electrical (Mk1c)
• Testing the Arduino Pro Micro stand-alone
• Compilation  Instructions
• Set to work instructions (Part 1)
• Calibration Instructions
• Set to work instructions (Part 2)
• Installing Gpredict and HAMLIB
• Operating Instructions
• Scaling it up
• Cautions
• Safety
• Limitations

//User configuration section:

//Please uncomment only one of each of the following MotorTypes, SensorTypes and SerialPort types:

//const int MotorType = PWMDIR;      //Please uncomment this line for the LMD18200T DC motor driver.

const int MotorType = FWDREV;     //Please uncomment this line for the L298N DC motor driver.

//const int MotorType = ACMOTR;       //Please uncomment this line for the triac AC motor driver.

//const int SensorType = LSM303D;   //Please uncomment this line to use the LSM303D sensor.

const int SensorType = LSM303DLHC;   //Please uncomment this line to use the LSM303DLHC sensor.

#define SerialPort Serial            //Please uncomment this line to use the USB port.

//#define SerialPort Serial1         //Please uncomment this line to use the TTL port.

The motor drive pins are: 5, 6, 9 and 10. Note: The Mk1a break pins are no longer supported or required.

The piezo buzzer pins are 16(+) and 14(-).

• We demonstrated the Mini Satellite-Antenna Rotator Mk1 to the Amateur Radio Victoria Homebrew Group.
• We presented and demonstrated the Mini Satellite-Antenna Rotator Mk1 at GippsTech 2016 on July 9th & 10th 2016.
• AR Magazine, June 2016. SOTA and Parks News by Allen Harvie VK3ARH. VK3 Show and Tell - Sunday 17 April 2016 - Brisbane Ranges National Park: "... Another highlight, among many, was provided by Joe VK3YSP. Joe set up his Portable Satellite gear, complete with mini computer controlled rotator for a demonstration earlier in the day and was ready and waiting for an early afternoon pass of amateur satellite designated FO-29. Right on cue, FO-29 came over the horizon and Joe completed what is believed to be the first WWFF contact from an Australian VKFF Park via Satellite. Joe exchanged greetings from the Park, the Park designator and name, and a valid signal report with Geoff VK2ZAZ. This was an effort by Joe and enjoyed by all present."

• We demonstrated the Mini Satellite-Antenna Rotator Mk2 to the Amateur Radio Victoria Homebrew Group
• We demonstrated the Mini Satellite-Antenna Rotator Mk2 to the Melbourne Space Program team on March 18 2017.
• We demonstrated the Mini Satellite-Antenna Rotator Mk2 at the Wireless Institute of Australia AGM on May 21 2017.
• We presented and demonstrated the Mini Satellite-Antenna Rotator Mk2 at GippsTech 2017 on July 1 2017.
• We demonstrated the Mini Satellite-Antenna Rotator Mk1 to the South East Radio Group on June 10 2018. It won first choice of the Home Brew prize!
• We presented and demonstrated the Mini Satellite-Antenna Rotator Mk3 and 4 at GippsTech 2018

1. The hardest part of the build was precision-marking and drilling the motor mounting holes. We recommend sticking adhesive paper labels to the diecast box, scribing construction lines on them using a digital vernier caliper, center-punching and drilling pilot holes first. A drawing of the motor mounting holes can be found in the motor datasheet here. Check three times - drill once.
2. Countersink the motor shaft holes on the inside of the rotator case and slip 5mm o-rings over the motor shaft before assembly for ingress protection.
3. Add two flat washers to the AZ motor mounting bolts on the side near the lid to counter the chamfer in the rotator case.
4. Install a cable gland on the bottom of the rotator case for the PC/Battery and Sensor cables.
5. Install the Motor Drivers to the case using countersunk bolts and stand-offs.
6. Install the Arduino Pro Micro against the case wall using two layers of double-sided tape on its flat side.
7. Prepare an Extra Heavy Duty Speaker Tripod. Try Altronics C0520A. Remove the speaker bracket if fitted.
8. Attach a 6mm shaft-hub to the top of the tripod using a 25mm irrigation-pipe threaded plug, 3mm cheese-head bolts, flat washers, spring washers and nuts. Fix with self-tapping screws to the tripod. Replace the grub screws on the shaft hub with cheese-head bolts or cap screws to obtain additional torque.
9. Attach the rotator's AZ motor shaft to the tripod and tighten the hub screws.  
10. Round the sharp edges of a lift arm made from 500x30x30x3mm aluminium angle.
11. Make a counterweight from a 101x51x25mm diecast aluminium box: Altronics H0451, Hammond 1590G or similar. Filled with lead to a total weight of 860g/1.9lb.
12. Attach the counterweight to one end of the lift arm with self-tapping metal screws.
13. Attach the Arrow antenna to the lift arm using Velcro. This is for quick release of the antenna and hand-held operation, if required.
14. Attach a 6mm shaft-hub to the lift arm close to the balance point. Ours was 140mm from the antenna end. A slight front-heavy balance offset will reduce backlash.
15. Attach the lift arm to the rotator's EL motor shaft using the 6mm shaft-hub and tighten the hub screws.
16. Enclose the sensor in 12mm double-wall heatshrink tube and crimp the front end. Mount the flat side of the sensor against the boom with a velcro strap around the boom. See: Sensor Orientation for details. Keep the sensor away from the VHF/UHF driven elements to avoid RF interference to the sensor. Don't use high power for satellites. Use ferrites on the I2C lines if necessary.
17. Here is an extreme close-up of the enclosure showing assembly details. Both the original shaft-coupler and new shaft-hub (recommended) mounting methods are shown:

1. Important: Bridge Jumper J1 on the Arduino Pro Micro.
2. Solder the four 6-way headers on to the TOP of the Arduino Pro Micro.
3. Crimp hookup wires into the housings.
4. Connect Pro Micro SDA, SCL, GND and VCC to the Sensor SDA, SCL, GND and VIN pins via a long flexible unshielded cable. We use flat telephone cable.
5. Connect Pro Micro pins 5, 6, 9 and 10 to the Motor Driver terminals (AZ PWM, AZ DIR and EL PWM, EL DIR respectively).
6. Connect Pro Micro pins 16 (+) and 14 (-) to a Piezo Buzzer to assist with calibration.
7. Connect Pro Micro GND to each Motor Driver GND and BRAKE terminal (The one on the same terminals as PWM and DIR).
8. Connect Motor Driver OUT1 and OUT2 terminals to the Motor terminals (be prepared to reverse these during testing as the motor pins are not polarised).
9. Connect Motor Driver V+ and GND terminals to your 12V supply via a cutoff switch and fuse (Caution: Don't connect until safe: The motors may move)
10. Connect Pro Micro USB port to the PC USB port. To fit the cable through the gland, cut a standard micro USB cable in half and re-terminate it. This port powers both the Pro Micro and Motor Driver electronics.
11. This schematic diagram has now been updated to support Version 6 software.

1. Important: Bridge Jumper J1 on the Arduino Pro Micro.
2. Connect Pro Micro SDA, SCL, GND and VCC to the Sensor SDA, SCL, GND and VIN pins via a long flexible cable. We use flat telephone cable.
3. Connect Pro Micro pins 5, 6, 9 and 10 to the Motor Driver terminals (IN1, IN2, IN3 and IN4 respectively).
4. Connect Pro Micro pins 16 (+) and 14 (-) to a Piezo Buzzer to assist with calibration.
5. Connect Pro Micro GND to the Motor Driver GND terminal.
6. Connect Motor Driver OUT1, OUT2 to the AZ Motor and OUT3, OUT4 to the EL Motor (be prepared to reverse these during testing as the motor pins are not polarised).
7. Connect Motor Driver 12V and GND terminals to your 12V supply via a cutoff switch and fuse (Caution: Don't connect until safe: The motors may move)
8. Connect Pro Micro USB port to the PC USB port. To fit the cable through the gland, cut a standard micro USB cable in half and re-terminate it. This port powers both the Pro Micro and Motor Driver electronics.

1. Important: Bridge Jumper J1 on the Arduino Pro Micro.
2. Connect Pro Micro SDA, SCL, GND and VCC to the Sensor SDA, SCL, GND and VIN pins via a long flexible cable. We use flat telephone cable.
3. Connect Pro Micro pins 5, 6, 9 and 10 to the Motor Driver terminals (IN4, IN3, IN2 and IN1 respectively).
4. Connect Pro Micro pins 16 (+) and 14 (-) to a Piezo Buzzer to assist with calibration.
5. Connect Pro Micro GND to the Motor Driver COM terminal.
6. Connect Motor Driver LOAD-1, LOAD-2 to the AZ Motor and LOAD-3, LOAD-4 to the EL Motor (be prepared to reverse these during testing as the motor pins are not polarised).
7. Connect a 100uF 50V Bipolar Capacitor across each of the motor windings.  
8. Connect the LOAD-1 and LOAD-2 Common and Motor Common to the 20VAC plugpack that comes with the AZ Channel Master rotator.
9. Connect the LOAD-3 and LOAD-4 Common and Motor Common to the 20VAC plugpack that comes with the EL Channel Master rotator.
10. Install an AC Mains safety cutoff switch. Do not use AC Mains voltages outside.   
11. WARNING: These AC Rotators are so powerful that they will cause severe damage and harm due to any malfunction or error. Never to be used unattended.
12. Connect Pro Micro USB port to the PC USB port. To fit the cable through the gland, cut a standard micro USB cable in half and re-terminate it. This port powers both the Pro Micro and Motor Driver electronics.
13. Note that the Azimuth rotator has to be modified using this modification procedure to remove the 360-degree stop pins. Caution: This modification will void the warranty. Note: The last step in the procedure requires you to drill out the two stop pins without leaving any metal swarf in the gearbox - piece of cake :-).
14. There is a video of the working controller here and a video of the working rotator here.

1. Install the Arduino IDE from https://www.arduino.cc/en/Main/Software. Note: Give the drivers ample time to install.
2. Connect the Arduino Pro Micro via a micro USB cable to the PC USB port.
3. Open the Arduino IDE
4. Select File | Examples | 01.Basics | Blink
5. Select Sketch | Verify/Compile (Ctrl+R). You should see "Compiling sketch..." followed by "Done compiling"
6. Select Tools|Board: Arduino Leonardo
7. Select Tools|Port: COMnn (Arduino Leonardo)
8. If you don't see COMnn (Arduino Leonardo) you may have to determine the virtual serial port used by the controller:
   1. On Linux start a terminal window and type: dmesg | grep "USB ACM device" Make a note of the tty device.
   2. On Windows start device manager and look under "Ports" for "USB Serial Device" or "Arduino". Make a note of the "COM" number.
   3. Select Tools | Port and the COM port number you noted earlier.
9. Select Sketch | Upload (Ctrl+U). You should see "Uploading...". The Arduino Pro Micro LEDs will flash 3 times. Then "Done uploading".
10. This indicates that you can successfully compile and upload an Arduino file.
11. Note: The Blink sketch does not blink the Pro Micro LED unless you add "#define LED_BUILTIN 17" to the start of the program and accept the compiler warning
12. If you can't upload. May we suggest: Closing the IDE. Disconnecting and re-connecting the controller. Starting the IDE again and repeating steps 4 onwards.

1. Open the Arduino IDE.
2. Select File|Preference to find out your sketchbook location.
3. Open the Mini Satellite-Antenna Rotator Arduino code file (RotatorX.zip)
4. Copy the RotatorX folder to your sketchbook location.
5. Select File|Open|RotatorX|RotatorX.ino. You should see eleven files open in the IDE as shown below.
6. Select Sketch Verify/Complile (Ctrl+R). You should see "Done compiling" and no errors (but please ignore any compiler warnings) as below.

1. Check the motor and sensor configuration. Click on the Rotator6 tab and find the following lines. The line with the motor or sensor you are using should start with const the other unused types should start with //const. I.E. Comment out the devices you don't use. The following shows the configuration for the type 1b with L298N motor driver and LSM303DLHC sensor.

//Constants

//User configuration section:

//Please uncomment only one of each of the following MotorTypes, SensorTypes and SerialPort types:

//const int MotorType = PWMDIR; //Please uncomment this line for the LMD18200T DC motor driver.

const int MotorType = FWDREV; //Please uncomment this line for the L298N DC motor driver.

//const int MotorType = ACMOTR; //Please uncomment this line for the triac AC motor driver.

//const int SensorType = LSM303D; //Please uncomment this line to use the LSM303D sensor.

const int SensorType = LSM303DLHC; //Please uncomment this line to use the LSM303DLHC sensor.

3. Connect the Mini Satellite-Antenna Rotator controller USB port to a PC or Raspberry Pi or whatever, but do not connect the 12V motor supply.
4. Start the Arduino IDE and open the rotator sketch
5. Press Upload to reboot the Arduino and start up the IDE Serial Monitor (button at top right). Select "Carriage return" from the dropdown box.
6. Type b<Enter>
7. You should see the raw sensor data (six numbers) as shown below. If you see "nan" or "ovf" there is a problem with the sensor or sensor connection.
8. Type a<Enter> to abort debug mode.
9. You now have to run the calibration procedure at least for the first time before you can proceed.

1. For version 4 software: Attach a piezo speaker to pins 10 (+) and 16 (-).
2. For version 5 software: Attach a piezo buzzer to pins 16 (+) and 14 (-).
3. Go on-line to calculate the magnetic declination in your area. Go to http://www.ngdc.noaa.gov/geomag-web/. Enter your country and city. Press "Add Lat/Lon" then press "Calculate" to get your magnetic declination. Say it is 11 degrees, 40 minutes, East. Convert this number to decimal degrees by dividing the minutes part by 60 and adding it to the degrees part, so that's 40/60=0.7 plus 11 equals 11.7. Use a negative number (-11.7) if it says West instead of East.
4. Make sure the 12V motor supply is disconnected. Connect the PC to the rotator using the USB cable.
5. Start the Arduino IDE and open the rotator sketch.
6. Press Upload to reboot the Arduino and start up the IDE Serial Monitor.
7. Type in e11.7<Enter> to enter the magnetic declination (make sure you type in your own value). Then s<Enter> to save it.
8. Now start the calibration process by typing c<Enter>.
9. You can abort the process at any time by typing a<Enter>.
10. When you have completed the calibration process, properly, just type s<Enter> to save the calibration data to non-volatile memory.
11. To calibrate the sensor you have to move it around very, very slowly. Don't bump it or even think about changing hands.
12. It helps to tape the sensor and the sensor cable to the back of plastic or wooden ruler and hold the ends of the ruler in each hand.
13. Move the sensor around. The piezo device will beep and you will see the 3D magnetometer (M) and accelerometer (G) errors and scaling factors changing on the screen.
14. You can pretty much keep moving the sensor all around until the piezo device stops beeping or the data stops changing, but there is a trick to doing it properly.
15. Think of the sensor as a cube with six faces. You need to point each face in the direction of the Earth's magnetic field and again in the direction of the earth's gravitational field. The gravitational field points straight down, while the magnetic field points up (in the Southern hemisphere) to the North at an angle of about 70 degrees to the horizontal. There are 12 directions and you have to move the sensor a little bit around each point until the piezo device stops beeping or the data stops changing.
16. For extra fun have someone video the whole process and then play it back at high speed!
17. Don't forget to type s<Enter> when you have finished.
18. You can then type r<Enter> to reset the controller and reload the stored calibration data.

1. Once calibration data is saved to the EEPROM you can continue to set the rotator to work.
2. Make sure the 12V motor supply is disconnected. Connect the PC to the rotator using the USB cable.
3. Start the Arduino IDE and open the rotator sketch.
4. Press Upload to reboot the Arduino and start up the IDE Serial Monitor.
5. In the IDE Serial Monitor type m<Enter> to enter the monitor mode.
6. You should see the rotator data as shown below, comprising: Current AZ and EL, Setpoint AZ and EL, AZ windup angle, AZ windup state, AZ and EL error.
7. Verify the Current AZ and EL numbers reflect the sensor true azimuth and elevation
8. Make sure the lift arm is disconnected. Connect the 12V motor supply.
9. Observe the IDE Serial Monitor display and observe the motor movement while looking directly at the motor shafts.
10. Point the sensor North East. The first number should be between 0 and +90. The AZ motor should turn CCW.
11. Point the sensor North West. The first number should be between 0 and -90. The AZ motor should turn CW.
12. Point the sensor 45 degrees Down. The second number should be between 0 and -90. The EL motor should turn CW.
13. Point the sensor 45 degrees Up. The first number should be between 0 and 90. The EL motor should turn CCW.
14. If a motor moves in the wrong direction, reverse the motor wires by swapping the OUT1 and OUT2 connections on the appropriate Motor Driver board.
15. Disconnect the 12V motor supply. Attach the rotator to the tripod. Attach the lift arm to the rotator. Attach the sensor along the boresight of the lift arm.
16. Disconnect the USB cable.
17. While carefully monitoring the lift arm, ready to disconnect the 12V motor supply if something goes wrong. Connect the 12V motor supply - there should be no movement.
18. Connect the USB cable. The lift arm should swing around to 0 degrees AZ/EL and stop.
19. Turn and tilt the tripod. The rotator should restore the lift arm to this home position.
20. In the IDE Serial Monitor type 30 45<Enter>. The lift arm should swing around to approximately 30 degrees AZ and 45 degrees EL.
21. If everything is working properly you may like to repeat the calibration procedure more carefully if you wish.  

• UPDATED 21 Aug 2023: The easy way to install and run Gpredict and HAMLIB for Windows is by using this file. You should download it and follow the directions therein. It will help you create a Tracking shortcut on the PC Desktop, which you can use to start HAMLIB and Gpredict in an orderly and unobtrusive manner. Closing Gpredict will automatically close HAMLIB.
• Click on the Tracking shortcut to start HAMLIB and Gpredict.
  
• Note: The rotator emulates the AMSAT Easycomm II protocol. It permits Gpredict to set the AZ-EL angle of the rotator and it is the only rotator protocol which supports rotator position feedback, allowing Gpredict to display the rotator position as well. However, because the Arduino Pro Micro uses the USB port handshaking lines for resetting the microcontroller, the position feedback part does not work properly with HAMLIB on a Windows PC. It works OK on Linux. While the rotator positioning will be OK the position display will not work. A work-around is to connect a USB to TTL serial adaptor board between the PC and the Pro Micro VCC, GND, TX and RX pins (remember to cross-connect the TX and RX lines). This board will power the Pro Micro from the PC. Then open the Arduino IDE and the rotator.ino file. Follow the instructions in the file to change the SerialPort from Serial to Serial1 and re-compile.
  

• Use a RPi Version 3 or 4 with built-in WiFi, or a version 2 with a USB WiFi dongle. Add a PiFace Real Time Clock if you want to use it portable.
• Start by downloading the the latest Raspberry Pi OS imager from here to create your micro SD card image.
• When your Raspberry Pi OS is installed and running, open a terminal window and execute the following commands.
• sudo apt-get update
• sudo apt-get upgrade
• sudo apt-get install gpredict
• Please install HAMLIB manually to get the absolute latest version.
  • Browse to: https://github.com/Hamlib/Hamlib/wiki/Download#latest-release
  • Note the latest release number e.g. 4.5.5. Replace the actual number wherever you see this number below
  • cd ~/Downloads/
    
  • mkdir hamlib
  • cd hamlib
  • wget https://github.com/Hamlib/Hamlib/releases/download/4.5.5/hamlib-4.5.5.tar.gz
  • tar -xvzf hamlib*
    
  • cd hamlib-4.5.5
  • ./configure
  • make
  • sudo make install
  • sudo ldconfig
• Plug the rotator into to a USB port and start the HAMLIB rotator control daemon in a terminal window:
  • rotctld -m 202 -r /dev/ttyACM0 -s 9600 -C timeout=500 -vvv
  • Where: 202 is the model number for a rotator emulating AMSAT Easycomm II protocol
    
• Plug the radio, via a CAT cable, into a USB port and start the HAMLIB rig control daemon in a terminal window:
  • rigctld -m MMM -r /dev/ttyUSB0  -s 38400 -T 127.0.0.1 -t 4532 -vvvvvvvv
  • Where: MMM is the HAMLIB model number for your radio and 38400 is the CAT baud rate of your radio.
  • See: https://github.com/Hamlib/Hamlib/wiki/Supported-Radios

• r - Reset. Prints the calibration data. Resets the rotator to the home position and resets the windup value.
  
• b - Debug mode. Prints the raw sensor data: Mx, My, Mz, Gx, Gy and Gz.
  
• c - Calibrate mode. Displays the calibration data only when it changes.
  
• d - Demo mode. Tracks linearly through the following AZ/EL points in a cycle: 0/0, 90/90, 0/180, 90/90 0/0, -90/90, -180/0, -90/90, 0/0
  
• m - Monitor mode. Prints current AZ and EL, set points for AZ and EL, the AZ windup angle, the AZ windup state, the AZ and EL error.
  
• a - Abort Calibrate, Monitor or Demo mode
  
• e - Enter Magnetic Declination. e.g. e11.7<Enter>. It is positive for East or negative for West.
  
• s - Save Magnetic Declination and Calibration Data.
  
• h - Help
  
• p - Pause
  

• Note: Our mini satellite-antenna rotator would not be suitable for EME (moon bounce) stations with narrow beam-width (parabolic) antennas.
  
• See our Mini Satellite-Antenna Rotator Mk2 to check if that meets your needs.
  
• There are two types of H-bridge motor drivers: Single PWM input with DIRection control (designed for DC motors) and Dual, FWD and REV, PWM inputs (designed for stepper motors).
  
• The L289N (FWD/REV) motor driver will handle 2A at up to 35V.
  
• The LMD18200T (PWM/DIR) motor driver will handle 3A at up to 55V.
  
• You can drive pretty big DC motors with those, especially at 24V. If that is not enough, there are larger motor drivers available.
  
• The following is a dual channel PWM/DIR 10A motor driver.
  

• The following is a dual-channel FWD/REV 60A motor driver.
  

• The sensor and Arduino should be located close together (about 1m max) because of the I2C bus interface. We can’t do much about that unfortunately. So the electronics box must be up at the antenna.
  
• The Arduino and the tracking computer can only be about 5m apart because of the USB interface. USB over CAT-V cable extenders are available for cable runs up to 50m. A more reliable option is RS-422 over CAT-V cable described in our Mini Satellite-Antenna Rotator Mk2. A better option is to use some ESP-32 WiFi devices.

• This is a DIY project for the experience builder. We are not responsible for your time, costs, tools, availability or substitution of parts.
• Beware of moving parts - Unit may move at any time without warning. Do not stand or permit anyone to stand in the vicinity of the operating unit.
• Beware of eye hazard - Moving satellite antennas are prickly. Eye protection is recommended.
• Beware of pinch hazard - Keep fingers away from moving parts.
• Beware of electromagnetic radiation hazard - Do not use with high power transmitters. Recommend 10 Watts maximum.
• Beware of electrocution hazard - Do not use near power lines.
• Beware of lightning hazard - Do not use in thunderstorms, rainy or windy conditions.
• Beware of fire hazard - The unit has no built-in over-voltage or over-current protection.
• Not suitable for unattended operation.
• Not suitable for fixed or permanent outdoor operation.
• Automatically connects to the Internet: Adult permission and charges may apply.
• Constant adult supervision of the operation is required to prevent injury, especially around children.
• Constant adult supervision of the operation is required to prevent damage to the unit, anything attached to the unit or anything in the vicinity of the unit.
• Constant adult supervision of the operation of radio transmitters is required at all times. You must check your licence conditions and operating frequency.
• Antenna, tripod, lift arm, mountings, cables or anything in the vicinity of the unit may be damaged under normal operation or due to software malfunction.
• The motors are light-duty and the antenna provides a lot of leverage on the motor shafts: Do not force them, tip over the tripod or drop its vertical shaft. Avoid striping the metal gears.
• Installation of a quick-disconnect connector in the power lead and safety DC cut-off switch is recommended.

• Suitable for rotating only a single, small directional antenna (e.g. A handheld, dual-band, Yagi antenna such as an Arrow antenna) using a counterbalanced lift arm.
• Not suitable for applications requiring high pointing accuracy e.g. parabolic dishes for EME. +/- 5 degree accuracy is possible with optimal calibration, but is not guaranteed.
  
• Unit will oscillate unless solidly mounted only on a rigid stand, such as a heavy-duty (speaker) tripod.