what is the difference between searchlight sonar and omni sonar

By MAQ Sonar. See more at www.maqsonar.com Pg.1

What is the difference between Searchlight Sonar & Omni Sonar?


Omni Sonar is the preferred sonar system by professional commercial fishermen. It is easy to understand the difference between an Omni and a Search Light (spotlight) or sector sonar through a quick example. Search Light sonar: A good way to understand search light sonar is to picture yourself holding a flashlight in a dark room. As you turn your body with the flashlight you can see only the area lit by the flashlight. As you continue to turn around 360 degrees each image would be lost and replaced by the next item shown by the flashlight. If I was in the room and did not want to be seen by you, I would just stay out of the beam of light from the flashlight. Search Light sonar works in the same way. To find fish, a set of elements move around a center core and show the fisherman the sea around him one slice at a time. At 14kts, it is possible for a fisherman to sail by a school of fish without ever seeing it. This is because the fish are out of sonar range by the time the “search light” moves to that side of the Vessel.

Sector sonar: A sector sonar is similar to like the searchlight sonar. It uses a bigger “light” that can see 90 degrees at one time. It is made up of a line of elements that spin around a central core but it needs 4 positions to cover 360 degrees. Like its cousin, the search light sonar is limited and can not provide you a full all around view in real time.

Omni vs Searchlight Sonar

Fish Found

Fish Lost

Omni Sonar All directions

at once

Searchlight Sonar Turning

around and around



The MAQ Omni Sonar: A Omni sonar sees 360 degrees at one time. Instead of having one row of sonar elements facing in one direction and moving around 360 degrees over a period of time, an Omni sonar has 256 sonar elements on a cylindrical core sending out a continual signal 360 degrees all at one time. To use a dark room example, it is the difference between having a flashlight and turning on a light in the center of the room. If I was hiding in the room and you turned on the light, you would find me quickly. The cost difference between a Omni, a sector, and search light sonar is due to the number of elements and the complexity of the electronics and software.

A real life example: The most popular search light sonar is one that operates at about 150 KHz. It can see fish at a maximum of 200M away in the best conditions. At 90 KHz, our Omni sonar can see fish in the shallow waters off the coast of Portugal at between 400M and 700M depending on the sea conditions, depth of the water and size of the fish school. It is currently used by more the 150 pelagic fishing vessels in North Spain, France, and Portugal to catch Benito, Sardine, Sea Bass, Red Tuna, Anchovy, and Mackerel. Benefits of the MAQ 90 KHz OMNI Sonar Over the Rest of Small Fishing Vessels! The benefits to the fisherman in using the MAQ 90 KHz Omni Sonar over their current spotlight and sector sonar are:

1. Time and Fuel savings. The Omni can find schools of fish and approximate size/weight so that smaller schools can be passed over for larger ones. It also allows a fisherman to select a school of fish and track them so that multiple small schools can be combined in one drop of the net. This maximizes the catch size without traveling out further to find one or two very large schools. This means that quotas can be caught in less time, which reduces fuel costs and running time.

2. Fish stock conservation through less destructive fishing practices. With

the Omni sonar, it is possible to see the front, back, sides, and height of the school of fish to be caught. If the school is too large for a single net, the omni sonar allows the fisherman to first see that it is too large, and then allows him to fish only the back of the school reducing the chances of killing the balance of the school.



3. Reduction in by-catch. Based on signal strength and relative positioning of fish school, it is possible for a fisherman to find only the species he is fishing. This means less by-catch and more productive fishery.

4. Minimize equipment loss and failure. The Omni sonar can monitor the net as it

is being deployed. It can help the captain avoid the cost of catching or ripping the net by clearly seeing all potential obstruction 360 degrees in the area the net will be deployed.

5. Longevity and reliability.

Outside of the hoist used to lower the sonar (for both the spotlight and omni sonar), the omni sonar has no other moving parts. The Search Light sonar has a motor that moves the element around a core. This is a source of failure for a Search Light and sector sonar and often results in yearly repairs and a life of 2 to 4 years maximum. The omni sonar has no internal moving parts and many of our vessels have had the same sonar for up to 20 years.

6. Versatility. The omni sonar is built to find many species in shallow waters. The spotlight sonar currently being used has issues finding some species of fish. For example, small schools of low lying fish (Pilchard or African Sardine), and, single Tuna are hard for a searchlight to find due to reflective angles and lack of Doppler compensation and control.

Whether it is the MAQ90, MAQ60, MAQ45, or the MAQ22, a MAQ Sonar can be used to find more than 140 pelagic and low water species found in the waters of the world.

what is the difference between searchlight sonar and omni sonar

Documents