Glideslope Flashcards
What are the two most common types of glideslope?
Null Reference and Capture Effect.
What is the normal total path Width of a NRGS?
1.4 degrees.
What is the additional feature of the capture effect glide slope?
There is an additional clearance transmitter below path that guarantees a full fly up in the critical area.
What is the glide slope standard service volume?
8 degrees either side of center line out to 10 miles.
What is flight inspection reported path width?
Half the total width (75uA to 75uA, ideally .70 degrees). Beyond the halfway points the path becomes too non-linear to be useful.
What are the three standard types of image array (reflecting off the ground) glideslopes?
Null Reference, Sideband-Reference, and Capture Effect.
What does modulation measure?
The modulated percentage of the radiated signal (the percentage of amplitude vs. the carrier signal). Must have 150 microvolts or greater to measure modulation level.
What is modulation equality and how is it measured?
It’s the balance between the 90 and 150Hz signal flown on a simulated glide path between 7 and 3 miles.
Should modulation equality be checked prior to phasing?
Yes, it is the baseline for adjusting phasing values.
What is the primary purpose of the ILS-2 level run (flight inspection holding pattern)?
It is to measure four angles, 190 microamps below path (190uA/150 Hz), 75 microamps below path (75uA/150Hz), on path, and 75 microamps above path (75uA/90Hz).
What are the glide slope angle commissioning and periodic tolerance?
Within +/-.05 degrees of the commissioned angle for commissioning, and within +10% to -7.5% of the commissioned angle for periodic.
What do you do if there is an unacceptable step in the vicinity of one of the 75 uA points?
You measure the width between the 60uA and 90uA points and use the measurement that most closely resembles the mean width (AFIS automatically converts this width to the equivalent of the 75uA width ratio).
What is symmetry?
The percentage of the 90Hz signal width to the total width.
What is structure below path?
It is the angle formed by the 190uA line of the 150Hz side. It has nothing to do with signal “structure.”
What should the structure below path angle be?
It should be at least 30% of the commissioned angle (30% of a 3 degree angle would be .9).
