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Vega AHRS-1 / MAG-1 Operating Manual

Page 9 

In-Flight calibration Procedure

Please see documentation supplied with the SP-6 for more information.

Fly the aircraft in safe area where you can perform random banked turns. Do not exceed the safety limits of the aircraft 
during the calibration flight.

Start the calibration in the Compass setup menu by selecting “Calibrate”. The AHRS-1 /
MAG-1 will display the compass calibration screen. You should see the compass heading
change to “111” to confirm that calibration has started.

Fly a number of banked 180 or 360 degree turns at different bank angles - i.e. shallow, medium and steep turns. Try to 
add many different pitch attitudes in various orientations relative to the field direction. It does not matter in what order you 
fly the maneuvers. A typical, good calibration tends to take 5-10 minutes of flight.

Do not activate any electrical equipment that creates large magnetic fields during the calibration process (for example 
starter motors, autopilot servos, landing lights etc). The heading starts reading 

111 

after you start calibration. After 36 

initial samples have been collected this changes to 

222

. This should take approximately one turn. Continue the flight

while maneuvering until the heading starts reading normally. This happens once the SP-6 has collected 100 distinctly 
different magnetic samples. At this point the heading should start showing reasonable numbers. Continue the calibration 
flight, settling into straight and level at intervals on different headings and verify the heading readout against an 
ACCURATE reference. Continue the flight until you find heading errors that are within 1 to 2 degrees, about the limit one 
can reasonably expect.

When satisfied, end the calibration by selecting “DONE” in the compass calibration menu. This will save the calibration to 
permanent memory in the SP-6. Should you not be able to achieve a good heading readout, please locate the compass to
a better location in the aircraft.

The AHRS-1 / MAG-1 displays the calibration sample count and fit percentage during calibration. The sample count will 
count up to 150 after which new samples replace the oldest samples stored. The fit percentage is a value from 0% to 
100%. The aim is to get to a value as close as possible to 100%. The fit starts displaying other than 0% after the first 36 
samples. Fit values of 98% and higher are considered good. If you cannot achieve this you do not have a good 
installation location for your compass. You may still get reasonably good heading accuracy despite a lower fit. However, 
to ensure long term accuracy please consider locating the SP-6 in a better area in your aircraft.

If the readout decreases suddenly by a large amount (for example from 85% to 42%), this is typically caused by a
strong time-variant magnetic field such as can be created by electrical equipment (motors, relays, current flow in cables). 
In such a case please either end and restart the calibration or continue the calibration flight until the fit error is acceptable 
again (the incorrect magnetic sample(s) will eventually be removed). It is advised to locate the interference source and
either move this or the SP-6 to a better location in the aircraft.

Note: should you move the SP-6 to a new location or fit new equipment close to the SP-6 you will have to perform the 
calibration again. There is no practical limit as to how many times you can perform and save a new calibration.

Summary of Contents for AHRS-1

Page 1: ...rce indication Advanced magnetic compass with a course steering feature and slip indication Can be setup as an individual compass display artificial horizon or both The AHRS 1 MAG 1 is connected to the AHRS Compass sensor packages by a simple CAN bus interface This allows for the optimum placement of the sensor packages in the aircraft More then one AHRS 1 MAG 1 unit can be connected onto the CAN ...

Page 2: ...l anti clockwise will scroll through the main displays Artificial horizon compass and turn and bank indicator F1 Up Button Menu System Softkey button Pitch level function 2 1 4 enclosure Can be front or rear mounted Rotary Control Up Down Enter Button Press the rotary control during the normal display screens to access the menu system Rotate anti clockwise for up down menu scrolling F1 Up Button M...

Page 3: ...pass 3 1 Artificial Horizon with Compass Pitch level function Should your aircraft fly nose up or nose down due to trim then you can press the F1 key to level the pitch as displayed on the horizon 3 2 Turn and Bank Indicator Slip indicator A step on the ball slip indicator can be enabled to appear below the horizon and compass displays The source of information for this indicator is derived from t...

Page 4: ...based on mechanical gyros Simply correct the horizon when you are finished or let the horizon right itself which will happen during straight and level flight Message displayed when the maximum bank pitch or yaw rates have been exceeded 3 3 Digital Compass 3 3 1 Compass Tape The digital compass tape can be displayed in 3 different ways The way the compass is displayed can be setup in the menu syste...

Page 5: ...degrees of heading error To cancel the course steering function simply press the F1 key again 3 3 3 The reverse course from heading display Press the F2 key to activate the reverse course display This display remains active for about 5 seconds before reverting back to the normal heading display 3 3 4 Heading stability issues You may find short term fluctuations of the heading occurring These tend ...

Page 6: ... 4 1 Exiting the menu system Press the F1 Up button to exit the menu system when the EXIT soft key is shown All changes made during navigation of the menu system will be saved in non volatile memory upon exiting The instrument will not save any changes if you remove power before exiting the menu system 4 2 Horizon Setup Compass Select ON if you would like to see the compass box on the horizon disp...

Page 7: ...nabled in the turn and bank indicator mode Slip Sense Select if you want the slip to have a high sensitivity or a low sensitivity setting Slip Zero This function allows you to set your slip indicator to exactly zero even if your aircraft tends to fly slightly wing down The procedure is to place the aircraft in a stable straight and level attitude during calm flight conditions and then select this ...

Page 8: ...ve to update the variation setting This setting may be ignored if you only use the magnetic heading display option Filter Select the filter factor for the compass heading A selection of NONE LOW MED or HIGH can be made This can improve the stability of the compass Slip Select if you would like to enable the slip indicator to be shown underneath the horizon display The slip indicator operates in th...

Page 9: ...ind heading errors that are within 1 to 2 degrees about the limit one can reasonably expect When satisfied end the calibration by selecting DONE in the compass calibration menu This will save the calibration to permanent memory in the SP 6 Should you not be able to achieve a good heading readout please locate the compass to a better location in the aircraft The AHRS 1 MAG 1 displays the calibratio...

Page 10: ...ISC Setup Miscellaneous Setup Backlight Select this menu option to adjust the backlight brightness Security Setup Select this menu option if you want to password protect the menu system Information This menu option displays information about the unit ...

Page 11: ...ading turn and bank or horizon is illegal 6 RS232 NMEA enabled GPS receiver message The AHRS 1 has the ability to be connected to a NMEA enabled RS232 GPS receiver to allow the AHRS 1 to use the actual ground speed in the attitude aiding algorithms The NMEA enabled RS232 GPS receiver must be able to output a GPRMC message The Recommended Minimum sentence defined by NMEA for GPS Transit system data...

Page 12: ...sensors themselves are functional 9 AHRS 1 MAG 1 Specifications Operating Temperature Range 10ºC to 60ºC 14ºF to 140ºF Storage Temperature Range 20ºC to 80ºC 4ºF to 176ºF Humidity 85 non condensing Power Supply 8 to 30Vdc SMPS switch mode power supply with built in 33V over voltage and reverse voltage protection Current Consumption Approx 73mA 13 8V backlight highest setting 33mA 13 8V backlight l...

Page 13: ... field by connecting the RS232 port to a PC and running the firmware update program Note that only the RS232 port can be used to upgrade the firmware Please see the Vega firmware upgrading document for more information 12 Installation 12 1 AHRS 1 MAG 1 Cable connections Main connector D15 connector Unit Female Cable Male D15 Pin Color Function 1 Red 8 30Vdc power via power switch circuit breaker a...

Page 14: ...rnal 1A fuse is recommended Connect the supply terminals to your aircrafts power supply The AHRS 1 MAG 1 can be used on both 12V and 24V without the use of any pre regulators Ensure that the supply voltage will not drop below 8V during operation as this may result in incorrect readings ...

Page 15: ... and relevant pilot s license This person has to make themselves familiar with the operation of this instrument and the effect of any possible failure or malfunction Under no circumstances does the manufacturer condone usage of this instrument for IFR flights IMPORTANT NOTICE You must make your own determination if the products sold by MGL Avionics are safe and effective for your intended applicat...

Page 16: ...SI ASV 1 Altimeter Airspeed ASI and Vertical Speed Indicator VSI EMS 1 Engine Monitoring System FF 4 Fuel Computer INFO 1 Information Display G force meter RTC Outside Air Temperature OAT Volts and Current display MAG 1 Magnetic Compass Indicator MAP 3 Manifold Pressure and RPM Indicator RPM 1 Universal Engine Rotor RPM Indicator TC 4 4 Channel Thermocouple EGT CHT Indicator TP 3 Universal Tempera...

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