Scottish marine technology solution provider Nautronix has developed a solution to overcome the issue of “scintillation” (solar activity interference) for vessel station-keeping with a new application of its acoustic positioning system known as NASNet.
The use of subsea acoustic systems as a back-up to primary satellite-based DGPS (Differential Global Positioning System) is not new. However, current systems available on the market have slower update rates than DGPS, which operates every second. As a result, should the DGPS become inaccurate, a vessel’s positioning capability could be compromised as the navigation desk receives slower inputs.
Aberdeen-headquartered Nautronix says that, because of the acoustic digital spread spectrum signalling technology used in the DPR variant of its NASNet system, the problem is overcome by offering equal update rates and position repeatability to DGPS.
This could be a critical factor in the next few years, with scintillation predicted to have a deteriorative effect on satellite signals in some regions of the world.
During certain explosive events on the sun, bursts of radio energy are produced which can knock out communications systems, and also impact on power supplies. The sun goes through what is called a solar cycle, on average, every 11 years, with swings between high and low activity.
Active periods occur when a high number of coronal mass ejections (CMEs) are emitted from the sun. These solar flares send out huge bursts of magnetic energy into the surrounding space – some in Earth’s direction. These high-energy particles can affect the various satellites that provide navigation and telecommunications services.
In particular, solar interference to GPS downlink signals appears to be a possibility during the lock acquisition phase, albeit the probability is very low and may occur just a few times in each solar cycle and only for a few minutes on each occasion. 2010 could be a lively year in this regard, though quite where the solar interference might strike is hard, if not impossible, to predict.
There is, however, talk of South America being subjected to scintillation-related communications problems. This, in turn, has implications for offshore Brazil, which is one of the busiest energy provinces in the world.
Nautronix MD Mark Patterson told Energy: “We believe NASNet DPR is the ideal back-up to DGPS for vessel station-keeping, especially as we enter another period of unknown GPS stability due to scintillation. We have been fully encouraged by our customers to develop this system and are hoping to conduct sea trials later this year.
“Nautronix has over 20 years’ experience in provision of dynamic positioning references systems and we believe NASNet DPR will significantly enhance operations by providing solutions to some current and future problems.”