If you have a high definition tuner on your TV set, you should be able to easily grasp the concept behind Lowrance's unique broadband sounder. It's very similar technology.

In the same way a hi-def tuner provides a much sharper and clearer TV image via digital processing, this "black box" filters and intensifies the signal from your transducer as it covers the seafloor and everything between it and the surface. It then sends the processed signal to the sounder head unit where it's displayed on the screen.

In very simple terms, the broadband technology "cleans" or "purifies" the signal image, making it sharper, more defined and ultimately more powerful.

Increased power is one of the major advantages of the broadband unit, in Fisho's view. It makes a standard 600kW transducer the equivalent of a much more expensive and powerful 1 watt transducer, meaning you can sound out far great depths than you would normally be able to without having to go to the hassle of mounting a 1 watt unit to your transom (an expensive and fiddly task for most trailer boats).

The box is designed to be mounted between your transducer and the head unit. It's a fairly compact box, measuring 210mm x 188 x 57.6, meaning it should fit behind or in most boat consoles. The unit is designed to be mounted on a flat surface and once installed runs automatically.

Paul Bakker, Lowrance's NSW sales manager, fitted the test unit in Fisho's Stabi-Craft 659 supercab in about 40 minutes. Anyone with basic knowledge of marine electronics should have no problem installing the unit, which basically involves powering it via a switched connection and then plugging the transducer cable in and connecting the unit to the head unit via an ethernet connector. If you run multiple units on your boat - say, one at the bow and another at the console - you can connect up to four head units to the broadband box via a Navico Expansion Port-1.

The black box matches with all 2007 and later LCX, LMS, X and GlobalMap Lowrance models with the five-pin ethernet connector. Depending on your unit, you may need to upgrade your sounder with free software from the Lowrance website. It works with all current Lowrance transducers and frequencies.
The outdated LCX-25c I had previously fitted to the Stabi wasn't compatible with the broadband technology so I upgraded to an LCX-37c, a more recent model with a bigger 8.4-inch screen.

After getting the install done, Paul and I took the Stabi out for a run in Jervis Bay to test the screen image with the black box operating and not operating.

I ran the boat over several bommies and drop-offs I fish on a regular basis. The screen image with the black box filtering the signal was noticeably cleaner than when I ran the boat over the same structure with the box turned off. The bottom signal was much stronger and schools of bait, individual fish signals and hard structure in the form of rocks and boulders were less "fuzzy".

It has to be said, however, that the standard image from a high quality sounder like the LCX-37c is pretty good regardless of any digital enhancements. This unit has an impressive 600 x 800 resolution with a super sharp SVGA, 16-bit colour, SolarMax TFT display. Compared to sounders of even just a few years ago, the colour images you see on a high-end unit like this are almost mind-blowing. The addition of the broadband technology simply sharpens the images so that what you see seems even crisper and finer.

We took a series of screen snapshots (reproduced nearby) to display the difference in the image display with the broadband box turned on and off.

Our tests, which also involved a bit of fishing resulting in Paul pulling a nice pannie snapper on a lime tiger 5-inch Gulp Jerk Shad from one of the more productive bommies in the bay, were conducted in water ranging from five to 20 fathoms.

According to Lowrance, the broadband unit will allow bottom soundings up to about 800 fathoms, which should open up a heap of new ground for trailerbaot fishos.

I'm looking forward to testing this out. Currently my 600kW transducer blanks out at 120 fathoms (just over the shelf at the JB Canyons where I do most of my gamefishing). I then switch to a 1 watt unit and have measured depths of about 300 fathoms.

Getting more than double will be pretty impressive, if in fact the broadband box actually achieves such amazing performance. It would be impossible to fish 800 fathoms but being able to spot really deep bait schools or find seafloor structure would be pretty neat. More importantly, the broadband unit should allow for more clarity and definition at key offshore fishing depths of 70 to 150 fathoms. More easily finding bait, drop-offs, thermoclines and fish, especially deepwater fish like blue-eye, gemfish, hapuka and cod, will be a key selling point for Lowrance's new gizmo.

For those with a technical bent, nominal output power for the broadband unit is 250W peak-to-peak / 31W RMS with analog output power equivalent 30,000W peak-to-peak / 3,750W RMS. That means you get high power performance without having to use high power hardware. As Lowrance's Paul Bakker explained, the digital processing software in the black box takes the place of bulky, expensive and battery-draining 1 and 3 watt transducers. Makes sense to me!

The Lowrance broadband sounder retails for $999 and is available from your local Lowrance dealer. Check out for more details.

By Jim Harnwell

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