Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Interference from VDE-SAT Downlink to the Incumbent Land Mobile
  System   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.

3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org