VHF+Omnidirectional+Range+-+Testing

Note: This material is for reference purposes only.

=VOR Testing= By: Jesse Landeryou

__Ramp Testing__

 * Test Frequencies**
 * With Nav-401 test box- 108.00 MHz
 * Without test box- 114.800 MHz


 * Nav-401L Test Box**

The Nav-401 test box is a unit that provides testing and calibration of VOR, LOC, G/S, MKR and COMM systems. It has a self contained signal generator for all the system previous mentioned. VOR sensitivity and audio functions can be tested using the Nav-401L.

Figure 1. NAV-401 Test Box


 * Procedure w/ Test Box**


 * To and From Indication
 * 1) Set the VOR bearing to 0 degrees on the test box and set the indicator to 0 degrees also.
 * 2) Verify needle centering is within +/- 3 degrees.
 * 3) Turn the OBS knob on the indicator until the TO/FROM indicator begins to change direction.
 * 4) Once TO/FROM flag changes continue rotating the OBS knob until the flag changes again, verifying that the TO/FROM flags are operational.


 * Needle Deflection/Needle Centering
 * 1) Set the VOR bearing to 0 degrees on the test box and the indicator course to 0 degrees.
 * 2) Note the deviation.
 * 3) Repeat steps 1 and 2 for every 30 degrees up to 360 degrees.
 * 4) Center the needle on the indicator and set +10 degrees for VOR bearing.
 * 5) Record percentage of deflection.
 * 6) Repeat steps 4 and 5 with the VOR bearing set to -10 degrees.


 * Audio/Sensitivity

>
 * 1) Set the VOR frequency to 108.00 MHz and set the test mode switch on the test box to VOR XTL.
 * 1) Set the VOR bearing to 0 degrees and set the indicator to 5 degrees for half scale deflection.
 * 2) Verify signal reception and that the flag is out of view.
 * 3) Increase the output attenuation on the test box until flag comes into view.
 * 4) On the test box set the MOD selector to 400 Hz.
 * 5) With the Nav audio on verify that a 400 Hz tone is received in the aircraft.
 * 6) Repeat steps 5 and 6 with the MOD selector set to 1020 Hz.


 * Flag Indication


 * 1) Set indicator to half scale deflection (5 degrees).
 * 2) Remove the 9960 Hz reference signal.
 * 3) Verify flag comes into view.
 * 4) Remove the 30 Hz variable signal.
 * 5) Verify flag comes into view.

Set the VOR frequency to 108.00 MHz and set the test mode switch on the test box to VOR XTL.


 * 1) Set the VOR frequency to 114.80 MHz to tune into YYC VOT.
 * 2) A morse code ident should be heard.
 * 3) Set the indicator to 180 degrees, the TO flag should appear.
 * 4) Set the indicator to 0 degrees, the FROM flag should appear.

__Bench Testing__

 * Procedure**

All parameters are the same for bench testing as ramp testing except various different frequencies between 108.00-117.975 should be test for sensitivity.

References: >
 * 1) http://www.austrocontrol.at/Images/TASKCARD%2040.1%20Avionic%20Test%20Procedure_tcm586-58943.pdf
 * 2) http://www.austrocontrol.at/Images/TASKCARD%2040.1%20Avionic%20Test%20Procedure_tcm586-58943.pdf
 * 1) http://en.wikipedia.org/wiki/VHF_omnidirectional_range