Investigation framework for L-band FCS EMC compatibility analysis

1. Présented by Luc Deneufchatel] Investigation framework for L-band FCS EMC compatibility analysis Sous-titre facultatif de la diapositive

2. Agenda • 1. Identification of system to be considered in the compatibility analysis • Overall view of the L band system usage • Type of compatibility analysis to be performed • 2. Nature of the interference to be assessed • In band interferences • Spurious radiation interferences • Out of band interferences • 3. Characterisation of the FCI component to be analysed

3. System to be considered within the L band

4. FCS Frequency Range GSM DME UAT SSR GNSS JTIDS 960-977 MHz ADJ ADJ ADJ CLS CLS IN 960-1024 MHz ADJ IN IN ADJ CLS IN 960-1164 MHz ADJ IN IN IN ADJ IN Types of compatibility analysis to be performed Three types of compatibility analysis depending upon the frequency dependency between the system IN: in band systemSystems operate in the same frequency range ADJ: in adjacent bandSystems operate in different frequency bands which are directly adjacent or separated by a few MHz (i.e. FCI in 960-977 MHz and UAT at 978 MHz). CLS: in close bandSystems operate in different frequency bands which are close but separated by more than a few MHz (i.e. FCI in 960-977 MHz and GNSS in 1164-1215 MHz).

5. Types of interferences • Three types of interference must be considered depending on the FCI component characteristics: • In band interferences: Assuming the FCS will be used, for instance, in frequencies above 977 MHz, in-band compatibility with DME will have to be studied. Some characteristics such as the temporal occupation of the transmitted signal (duty cycle) and the transmitted power will have an impact • Out of band interferences: Out-of-band emissions are transmitted outside the necessary bandwidth but exclude spurious emissions. Out-of-band emissions from a transmitter will cause an increase of background noise in the victim receiver passband • Spurious radiation interferences: Spurious emissions begin at +/- 250 % of the system bandwidth from the its center frequency

6. Essential system characteristics • For the interferer system (the future FCI component): • Transmission Filter (bandwidth, filtering slopes). These parameters will influence the levels of OOB and spurious emissions. • Signal Modulation (useful bandwidth, spectrum fall off rate).These parameters will influence the levels of OOB emissions. • Signal Polarization • Time-domain Characteristics of Signals. Several separate cases have to be considered: • a.Pulsed emissions (transmitted power, length of pulses, duty cycle). Such emissions are transmitted by DME and JTIDS systems, for instance. • b.   Bursted-Type emissions (transmitted power, length of bursts, duty cycle, time/amplitude profile of bursts). Such emissions are transmitted by UAT for instance. • c.       Continuous emissions (transmitted power) • For the victim system: • Interference Susceptibilities: The currently available susceptibility values are provided within documents (ICAO Annex 10, EUROCAE and RTCA documents) They are limited to typical in-band or adjacent-band signals such as Continuous Wave, wideband noise and DME-like signal. Those values may not be directly valid for the candidate systems • Reception Filter: The level of OOB and spurious emissions transmitted by an interferer and received by a victim receiver will depend on the characteristics of the reception filter • Use of a Mutual Suppression Bus: The FCS may be connected onboard to a mutual suppression system in order to limit mutual interference with other systems

7. Compatibility analysis scenario • Use of “source-path-receiver” methodologyrequires to identify: • Potential interference sources • Interference-victim receiverencounter scenario • Receiver performance in presence of interference • The following cases need to be investigated: • Co-site compatibility onboard the aircraft • Air-to-Ground compatibility • Ground-to-Ground compatibility • Ground-to-Air compatibility • Air-to-Air compatibility