## The radio-navigation subsystem LOCerr

The masked subsystem block LOCerr (Localizer steady-state errors), which is contained in the ILS-sublibrary of the blocklibrary NAVLIB, computes the steady-state error in the localizer signal caused by the ground equipment. The magnitude of the error is computed according to ICAO guidelines. Both localizer misalignment and steady-state errors in the localizer sensitivity can be taken into account. See the references below for more info about the theoretical backgrounds.

Other blocks in the ILS sublibrary of NAVLIB are: Nominal ILS signals, GSerr, GSnoise, and LOCnoise, and the example system ILS example.

### Inputsignal

Nominal value of localizer current iloc, [micro-Ampere]

### Outputsignal

Localizer current iloc, including steady-state errors, [micro-Ampere]

### Block-parameters

- performance category (1, 2, or 3, see the FDC user-manual or ref.[1] for more info)
- percentage of maximum allowable error in localizer sensitivity (iloc = Sloc * Gamma_loc, where iloc is localizer current through cockpit instrument, Gamma_loc is the angle between the line from projection of aircraft's c.g. on ground to localizer antenna and runway centerline, Sloc is the localizer sensitivity)
- percentage of maximum allowable localizer misalignment
- distance from runway threshold to localizer antenna, [m]

The block-parameters can be specified in dialog-boxes which appear after double-clicking the block LOCerr.

### References

Apart from the FDC user-manual, the following reference contains more information about the ILS signals:

1. M.O. Rauw: A Simulink environment for Flight Dynamics and Control analysis - Application to the DHC-2 'Beaver', part I: Implementation of a model library in Simulink. Delft University of Technology, September 1993 (also contained in the STAR database of NASA, report number NONP-NASA-SUPPL-DK-94-28027)
2. Anon.: Approach and Landing Simulation. AGARD report 632, Ames, 1975