Adding RMUs to Moon
Installing and connecting a new RMU is not more demanding than connecting a new computer (and its radio receiver) to internet and placing an antenna on the building.
Choosing the right location to install RMU(s) antenna(s)
In order to maximise MOON monitoring results, ANSPs should position their local RMU(s) ideally like this :
- the RMU(s) antenna(s) should be in a position with direct view to local airborne and grounded aircraft traffic.
- the RMUs antenna are totally passive and can be mounted on a common support close to each other.
- the RMUs antenna should be in direct visibility of local VDL 2 (active) ground-stations from Communications Service Providers, (although a very close proximity could saturate and deteriorate RMU’ reception), in order to monitor also uplink traffic.
- for multi-frequencies monitoring operation, a RMU can share a common antenna for several radio receivers, through a VHF–splitter, although this will reduce the received power and hence the radio coverage. Otherwise, several antennas (one per VDL channel) should be installed.
- the RMU radio and PC should be positioned in a shelter or building close to their antenna(s) and connected to internet ADSL or PENS networks
RMU internal structure
A typical RMU includes several equipments:
- A VHF reception device that implements VDL MODE 2 demodulation, connected to an external antenna
- A computer connected to the VHF radio that performs the acquisition itself and stores the capture files thanks to a specific software
- An internet connection, typically DSL based.
The picture below illustrates this typical configuration .
CMS connection requirements details
The CMS is configured to fetch the collected traffic on every RMU through internet. Consequently the RMUs will have to be connected to internet with the following requirements:
- The connection has to be constantly present, typically like with ADSL
- The upload bandwidth have to be 128 Kb at minimum
- The public IP address where the RMU is reachable shall be fixed (contrary to dynamic)
- The RMU local port 22 (SSH) shall be reachable using a specific public port of the public IP. (TCP redirection)
A specific protocol is used for the communication protocol between any RMU and the CMS.
Note: the option for connection of RMUs to CMS through the Pan-European ATM Network (PENS) is envisaged for the ANSPs