Up to now most of the sensors installed by the Spanish scientific community in Antarctica have been placed close to the stations, because that makes data collection and data transmission easier. This proposal is a step forward for the communication capabilities of Spanish scientists in Antarctica. The main goal is the design of a sensors network able to transmit their data from very remote places (even in the continent) to the Antarctic Station Juan Carlos I. This network will use the Near Vertical Incidence Skywave (NVIS) that allows the communication between nodes up to 200 Km away using vertical reflection in the ionosphere in the HF band (3-30 MHz). As both the transmitted and received signal come from the upper part of the atmosphere, no line-of-sight is needed and you can have any obstacle without any loss of the signal. Then, every single node can behave as a repeater if necessary, so large areas can be covered, provided that the distance between two contiguous nodes is less than 200 Km. The transmitted power for each node is low, and that improves the autonomy of the system. The sensor network will also allow bit-rates up to tens of kbps , good enough for most of the sensors for the transmission of medium/high quality digital voice. The proposal also includes the installation of a complete prototype of sensors network with repeaters, for both data and digital voice links.
For the design of the sensors network, first the NVIS channel has to be sounded via pattern sequences. These soundings will be compared with the data obtained by the ionosonde installed at the Antarctic Station Juan Carlos I. The main parameters of the channel will be studied and a new model for the NVIS channel will be proposed.
Then, we will design the best transmission system in terms of bandwidth and modulation that fits the NVIS channel. Once the physical layer is defined, a new link and network protocol will be designed in order to have a mesh network where the nodes can behave as repeaters when necessary and guarantee the transmission through long distances.
A sensors network like this makes the area of influence of Spanish scientists wider, and makes new experiments no possible until now feasible. It also has straightforward applications in case of natural disasters when most of the communication systems (mobile phones, private radio) crash. That is why the challenge 8 “Security, protection and defense” makes sense with our proposal. In case of natural disasters and terrorism attacks, HF networks using NVIS are the most agile and economic solution to communicate the affected area with other parts of the country.
- David Altadill from Ebre Obervatory