|
First LOIS Workshop, June 17-19, 2001 Växjö University, Sweden |
|
||||
Åke Steen
ake.steen@remspace.com, www.remspace.com
RemSpace Group
Linköping, Sweden
AbstractWhat is a multi-point system? The question becomes meaningful, interesting and also fascinating when the characteristics of a multi-point system automatically is modified or optimised as the circumstances or the signal is varying. Historically, both in science and in society, collection of data/information has been carried out simultaneously at several points for a long time. However, the traditional view has been to regard a multi-point measurement system as a number of identical stations connected by communication channels. Today it seems better to consider the communication channel as being a part of the whole collective system. Many interesting aspects arise when an advanced (collective) system measures a complicated signal (perhaps a 3-D time varying signal). Is it meaningful to use the concept of a control centre or should all stations be considered as equals with possibilities to influence the characteristics of the other stations. Is it possible to have a unique status definition of the collective system if each station can modify the measurement mode of the other stations? An interesting analogy is the democratic system as a method to rule a modern society (the individuals contra the parliament).LOFAR/LOIS is a true multi-point system using radar wavelengths to gather information about distant sources in the far away universe, in the solar system or in the atmosphere of the Earth. The initial design of a multi-station system must seriously take into account the risk of creating an enormous workload if not each individual station has a high degree of reliability, ease of maintenance and remote upgrading. A multi-station system must be flexible to use but the design of the infrastructure must consider some basic requirements in multi-station technology, e.g., standardisation of components and sub-systems (a replacement of one single component at 200 stations can be expensive), each individual station must be able to inform about its hardware as well as software status, the time aspect (an advanced system should probably be operational for 10-20 years). Although it is possible to visit each station, the total number of stations makes such approach unrealistic. The design must instead follow the design of satellite projects, i.e. it is normally not possible to visit the stations.
The LOFAR/LOIS concept includes high-speed fibre optics communication
links. In atmospheric and ionospheric physics the radar measurements
have frequently been accompanied by optical measurements, e.g. 3-D
auroral imaging. At mid-latitude other atmospheric phenomena can be
studied by the combination of radar and optical imaging, e.g.
airglow, atmospheric waves and also active airglow modification
experiments. We also discuss the possibilities of adding imaging
systems to the stations in LOIS thereby making combined radar/optical
3-D tomographic imaging a reality in real-time.
|
|
|