On the Interference from VDE-SAT Downlink to the Incumbent Land Mobile System

TL;DR

This paper analyzes the potential interference from VDE-SAT downlink to incumbent land mobile systems within the VHF maritime mobile band, proposing a regulatory-based method to evaluate impact and protection measures.

Contribution

It introduces a method to assess satellite interference on land mobile systems using regulatory constraints and PFD masks, addressing a regulatory gap.

Findings

Regulatory constraints influence satellite emission limits.

PFD masks can protect land mobile systems from satellite interference.

Implications for future spectrum regulation and satellite deployment.

Abstract

Although both frequency utilization plans for VDE-SAT downlink are within the frequency range from 156.0125 to 162.0375 MHz which belongs to the VHF maritime mobile band, on land, this band is mostly allocated for conventional and trunked land mobile systems by safety agencies, utilities and transportation companies. The challenge lies in the fact that there is no existing regulatory rule directly established for protection of the land system against the satellite system or the like, and hence the evaluation of the potential impact on the incumbent land systems becomes difficult if not impossible. A method adopted in the current analysis is to place general restrictions on the emissions from the satellite stations inferred from the existing regulatory rules for interference protection between land systems specified by ITU and ECC. The restrictions are expressed in terms of values of maximum allowed power flux density (PFD) emitted by any space stations to the surface of the Earth at all possible incident angles in a reference bandwidth that serves as a protection mask for the land system such that the actual interference that the land system experiences is no worse than that from another land mobile system permitted by these regulations. This article examines the regulatory constraints specified by ITU and ECC in these bands and its implications on the PFD mask.