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Hydroacoustic trigger systems

In order to work efficiently, most commercial fishing vessels have more than one hydroacoustic system. Numerous sonars ane echo sounder systems may be in use at the same time. When all these systems transmits simultanously, interference may become a problem.

The key to achieve a sustainable fishery is the ability to perform a preliminary evaluation of the fish schools. The best way to evaluate those fish schools is by means of hydroacoustic equipment like echo sounders and sonars.

In order to collect information for the decisions you need to make, the new generation of fishing vessels have more and more hydroacoustic equipment. These systems often work simultaneously, and transmit acoustic pulses ("pings") into the water with different frequencies, output power and pulse durations. If these acoustic signals were visible, you would see something similar to the waves in the water when you throw several different sized stones at the same time.

Most acoustic equipment today has interference reject abilities. These are filters that removes the transmission pulses from the other systems. However, those foreign pulses are often so powerful that it may be nearly impossible to detect the echoes that you are looking for. They may be completely lost in the interference.

There is only one good way to avoid this interference, and that is by synchronizing all the transmission pulses. If you do that, all the equipment will transmit at the same time. This eliminates the annoying interference between them. Still, your systems may have diffrerent transmission rates. Some "ping" very fast, others are slower. By setting up one of the hydroacoustic systems as "master". all the other systems will transmit only when permitted.