Lowrance Transducer Information

Transducer Selection

Choosing a transducer is an important part of designing your sonar system. The sonar image on your display starts with the transducer, so its characteristics greatly affect the performance of the system. With so many different technologies, transducer selection may seem mystifying. The main points to consider are how will it be mounted, what views do I want and what frequencies do I need.

  • How will it be mounted?
    • Most inland water boats are fitted with a transom or a shoot-thru-hull broadband sounder™ transducer as well as a second broadband sounder transducer on the bottom of the trolling motor, if equipped. Today, a transom mounted StructureScan HD® transducer can be found on most inland fishing boats.
    • Most bay/flats/offshore boats are fitted with a transom mount or a thru-hull transducer.
  • What views do I want?
    • Broadband and CHIRP can be accomplished with the same transducer—the difference is how the signal from the transducer is processed by the sonar module.
    • StructureScan HD requires a different style of transducer
    • SpotlightScan requires a dedicated transducer mounted to a foot-controlled trolling motor.
  • What frequencies do I need?
    • Here is a quick breakdown:
      • Low CHIRP or 50kHz—Lower frequency means higher power for deep-water fishing.
      • Medium CHIRP or 83kHz—Specifically designed to give the widest coverage area, 83 kHz is ideal for watching a bait under the transducer in shallow water.
      • High CHIRP or 200kHz—Higher frequencies display a higher resolution image making it easy to discern fish from structure or structure from the bottom.
      • 455kHz—Built into StructureScan HD and SpotlightScan, 455kHz allows for scanning of a large range with picture-like detail.
      • 800kHz—Also built into StructureScan HD and SpotlightScan, 800kHz yields less range but even higher resolution detail than 455kHz.

Sonar Technology

CHIRP

CHIRP sonar is cutting edge echosounder technology. Unlike the single frequency of the Broadband Sounder technology, CHIRP continuously sweeps a spectrum of frequencies. Sweeping frequencies makes two improvements to the sonar image:

  • Better target separation- Because CHIRP uses a range of frequencies, rather than a single pulse, CHIRP sonar greatly improves the ability to distinguish fish targets that are very close together or on the bottom. Fish become easier to differentiate from the structure they are holding to.
  • Less interference from errant noise that would have been picked up by a single frequency sonar. CHIRP creates a unique range of frequencies and listens for only those sonar returns, this gives CHIRP sonar the ability to distinguish between what is a real echo, and what is just extra disturbances bouncing around underwater.

Broadband Sounder

Single frequency sonar—also referred to as Broadband—is commonly annotated as 50kHz, 83kHz, or 200kHz. Broadband is essential sonar technology at its finest. Broadband relies on pings and echoes from a single frequency. This technology is great for tracking bottom, finding schools of baitfish, displaying predator fish, and bait tracking.

StructureScan HD

StructureScan HD allows users to scan an area with a very high frequency signal, producing picture-like images. 455 and 800kHz frequency selections allow users to choose between 455 for scanning great ranges, and 800 for close-in, higher resolution detail. StructureScan HD literally turns the sonar paradigm on its side with the ability to search to the left and right of your boat rather than only below. StuctureScan HD imagery can be overlaid on top of cartography for a detailed, up-to-date view of structure in relation to your position. Called StructureMap™,this is excellent way to find underwater structure and changes in bottom layout.

SpotlightScan™

SpotlightScan is boater-controlled directional sonar that allows anglers to scan an area they are interested in fishing while on approach. For use with cable-steer trolling motors, it aims two sonar signals similar to StructureScan HD in a specific direction. An angler can view productive fish-holding spots, such as drop-offs, channels, and underwater structure, before positioning a boat over top of them making it easier to find and cast to fish.