Intersystem interference - 2017


  • Patrik Eliardsson
  • Mikael Alexandersson
  • Sara Örn Tengstrand
  • Peter Stenumgaard
  • Johan Hedström
  • Björn Lindahl
  • Sara Linder
  • Karina Fors
  • Kia Wiklundh

Publish date: 2018-03-05

Report number: FOI-R--4532--SE

Pages: 37

Written in: Swedish


  • intersystem interference
  • EMC
  • detection system
  • RF-Oculus.


Intersystem interference is the problem that arise when other radio signals and unintentional electromagnetic interference adversely affect the reception of a communication system. Military platforms usually consist of electrical equipment and radio systems on a small surface, and the risk of intersystem interference is therefore high. Intersystem interference leads to a deterioration of the communication system performance and may affect the overall abilities of the military forces. The following report summarizes parts of the work performed during the year within FOI's intersystem interference project. The work consists of several different parts, but they all aim to handle the problems due to intersystem interference. The report summarizes work and results regarding: 1. New functionalities in the intersystem interference tool GENESIS, 2. A method for identifying the dominant interference source, 3. Development of a portable interference detection system, 4. A method for measuring the interference environment in frequency bands where sporadic radio transmission are occurring, and finally 5. Impact of narrowband interference on OFDM system. The report, among other things, presents a new method, with a so-called total ICF, to be able to calculate the impact of an interference environment consisting of multiple interference sources, which can be all from impulsive to AWGN-like (AWGN - additive white Gaussian noise). The method can also be used to determine which interference source is the most harmful one to a communication system. The report also describes FOI's developed detection system, RF-Oculus, which can be used to detect interference, mainly in so-called quiet frequency bands like the GPS band (GPS- Global Positioning System). It is also shown how the system can be supplemented with a method of measuring the interference environment in frequency bands that are sporadically used for radio transmissions. Finally, it is shown in what way OFDM systems (OFDM - Orthogonal Frequency Division Multiplex) are affected by narrowband and broadband interference. OFDM is a technique commonly used in mobile communication standards and standards for local area networks. The result shows that an OFDM system is significantly more sensitive to a narrowband disturbance than to broadband AWGN. This is an important fact to consider when designing communication systems and when new emission requirements are to be determined.