## The radio-navigation subsystem GSerr

The block GSerr (Glideslope steady-state errors) is contained in the sublibrary ILS of the blocklibrary NAVLIB. It computes the steady-state error in the glideslope signal, caused by the ground equipment. The magnitude of the error is computed according to ICAO guidelines. Both glideslope misalignment and steady-state errors in the glideslope 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, GSnoise, LOCerr, and LOCnoise, and the example system ILS example.

### Inputsignal

Nominal value of the glideslope current i_gs, [micro-Ampere]

### Outputsignal

Glideslope current i_gs, including steady-state errors, [micro-Ampere]

### Block-parameters

- performance category (1, 2, or 3, see the References for more info)
- percentage of maximum allowable error in glideslope sensitivity (i_gs = S_gs * epsilon_gs, where i_gs is the glideslope current through the cockpit instrument, epsilon_gs is the angle between the line from aircraft's c.g. to glideslope antenna and nominal glide path, and S_gs is the glideslope sensitivity)
- percentage of maximum allowable glideslope misalignment
- nominal glideslope elevation angle

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

### References

Apart from the FDC user-manual, the following references contain 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
2. Anon.: Approach and Landing Simulation. AGARD report 632, Ames, 1975