North Australian FISH FINDER forums

What's the story with the general takeup of live imaging technology in NT?

Pretty popular in other places in Aus but a lot of uncertainty 'cos most (not just fishos) seem to be a bit confused and therefore wary about expense.

CHIRP was like that when it first came out. Nobody knew much about it (that hasn't changed) and therefore couldn't clearly show what advantage it "brought to the fisho's table".

Nobody wanted to know the "ins-and-outs" of a cat's derriere about CHIRP. Simply what advantage/s it brought and was it worth the money.

I'm happy to put up a couple of things about live/animated imaging. Take some of the mystery and confusion out of the subject.

“Live imaging sonar” is a process similar to that used in cartoons and movies. That process is called animation which brings with it a real-world fact vs fiction context.

So.. is there anything new about live imaging? No. Its been around for a long, long time (since 1835).

Instead of using ingenious mechanical methods of showing still images of objects seeming to move and interact with each other like zoetropes, flipbooks and acetate reel – reel movies photographic images on long reels, these days the process is electronic.

So, what are we actually talking about with live imaging sonar? We’re looking at the apparent “live” interaction between our lure and fish.

This single image shows what live sonar imaging is all about.
By displaying moving images of the fish AND the lure together on the one screen, it acts like an alert fisherman’s early warning of a imminent bite. Its called animation

In the image above, we can see both the lure AND the fish in “real” time. That’s animation. The principle of animation isn’t new. In fact, the principle is from 1835 (189 years ago). Ever heard of a zoetrope?
Spin the wheel, look through the slots and the horse appears to be galloping smoothly.
The same effect can also be obtained by the use of a flipbook which was invented in 1860 (164 years ago). A “flipbook”?
A slightly different image is placed on each separate page and the “book pages” are then flipped by release from the thumb. Each succeeding image changes slightly to produce apparent image motion just like the zoetrope of 25 years earlier.
Get the idea of animation?

Now put the images (each one is slightly different) on a long ribbon of film acetate, wind it on a reel and run it through a projector where each image is displayed sequentially at speed onto a screen. And what do we have?..... Moving pictures. Movies.

The images on the film are separate individual small still photographs of a scene where the objects are moving around but photographed at high speed. A one second sequence of film consists of 25 separate still photographs or images.
A 10 minute animated film (cartoon) requires 15,000 still photographs/images.

To produce the photographs to put on the film, we need a camera. A film camera automatically puts the still photographs (each one slightly different like the zoetrope process) on the acetate film. It takes about 135,000 images for a 90minute feature film.

Can we do the same thing underwater (still photographs or movies)? Sure can. We just need waterproof cameras and………..light. Geez, that means battery as power for light and camera. Getting complicated.

Can we use some other device with different types of waves to scan objects when there is no light? Can we do that? Sure can. Its called sonar.

Sonar uses acoustic/sound waves. Waves “above” the sound/hearing band are called ultra (from Latin meaning above/beyond). Hence these waves are “ultra-sound”. That sounds familiar. Non-intrusive scanning of body parts.

Marine science also had a need for non-intrusive imaging to study fish behaviour. Historically marine science was intrusive either by investigatory disection in a laboratory or visual examination of fish behaviour underwater. Observe fish in their natural environment with no intrusive surgery, lights or divers.

A firm called Sound Metrics Corporation is considered to be the originator of acoustic imaging from 1999 (but acoustic imaging had been around for 15 or so years before that). SMC developed the concept and image quality. We all know about ultrasound imaging for internal body scans to avoid surgery.

As we all know from the different frequencies used in sounders, higher frequencies provide better “definition” of objects scanned. The downside is that these higher frequencies ( 800 – 1000 khz) don’t travel so far underwater compared to the lower frequencies (50 – 80 khz).

Our sounders/scanners max out at 1000 – 1200 khz (called mega) AND they’re low powered. Scientific image sounders operate up to 3000 khz and also operate at higher power levels so the quality of the images is much better than we fishermen could ever hope to achieve.
http://www.soundmetrics.com/Image-Galle ... lity-Water

The link above is a video of a scanned human hand moving around underwater with zero light. Its not low light scanning or light enhancement technology. Its zero light scanning.

A lot of boats have it. I use it run the runoff rivers but not much in the shallows/harbour

Tks. Same down this way with users. I've got one (can't talk credibly about them if haven't used one). Do that with everything with finding out facts and not opinion.

There's more confusion about this stuff than with intro of CHIRP (more variables and more user interpretation needed). Info from retailers, experts and gurus a dog's breakfast.

Bit more on live imaging

Most fishermen don’t need or want to know the ins-and-outs. They simply want to know what improvements live imaging brings to the table and how to use it.

Let’s try to keep it as simple and as basic as possible.

Three recreation sonar manufacturers have 3 different versions in respect of 4 different brands. It gets worse.

1. Active Target 2 for Lowrance and Simrad sounders;
2. Livescope for Garmin; and
3. Mega Live for Humminbird.

Each of these versions has 3 common ways of looking at the water column.

A thin vertical deep slice mainly in front of the transducer (forward mode), a thin vertical deep slice in front, underneath and behind the transducer (down mode) and a wide shallower plan of what’s in front of the transducer called (wait for it) called Scout, Landscape or Perspective modes depending on which manufacturer.

These marketing gurus couldn’t help themselves. Just had to complicate things with 3 different names for one of the modes.

The 3 different modes really require 3 different transducers to produce the 3 different views. However by imaginative mechanical design, the manufacturers use only 1 transducer and change to the required mode by physical manipulation of the transducer and mounting pole.
It's mounted on a separate transducer pole over the side of the boat and the pole can be rotated to change the direction in which the transducer is “looking” along with “flipping” the transducer between vertical (forward and down modes) to horizontal for Scout, Landscape or Perspective modes.

Those manipulation options allow the selection of 3 different types of beams depending on the waters.
Down mode Forward mode
Perspective, Scout or Landscape mode (sometimes called “shallow mode”)
All those words mean the same thing (searching/finding) with different names. The special transducer (which is flat) is flipped onto its side and the beam is horizontal and looking forward or in any direction that you want to point it by rotating the mounting pole.

Remember that strange term called stitching? All that means is electronically joining the edges of the beams together to smooth over the beam overlaps so the total image doesn’t seem like torch beams radiating outward.
Searching like that needs as wide an arc as possible. Otherwise, somebody has to keep swinging the transducer side to side (or mechanically rotating it like a radar scanner) to cover the angle that we want to see. Doesn’t a 360 mega system already do that?

To counter that need, we use a transducer that has a wide angle (120 or 135 degrees). That means the transducer doesn’t have to be “swung” or rotated much at all.

This particular transducer has a wide beam angle of 135 degrees when “flipped” to flat.

Now look at these 6 beams. Garmin claims to have 6. Each beam is on a different azimuth (direction to horizon) with the whole electronic range extending from 530 khz to 1100 khz (or there-abouts). That’s each beam covering a total of 570 khz and scanning the bottom thousands of times per second.

There is one major fallacy in live imaging and that is the width of the beams. No transducer used on recreational vessels is capable of producing beams accurate to 1 degree in width. Research/miliary maybe but not our hummingbird/Lowrance/garmins.

We can design the electronic characteristics of the frequency ranges of the transducers so we can easily work out the frequency width of the beams with the high precision micro-processing available.

The closest that we can get is the 6 beams “cover” 135 degrees making each of the 6 beams covering 135/6 = 22.5 degrees.

But we’ll leave that for another day about polar diagrams.

Garmin probably stole a march on the other manufacturers so have had a while longer to “get it right”.

There’s one suspect claim in the “resolution” debate of animated imaging and that is that a updated transducer is responsible for increased resolution/clarity/definition available from 1 particular model of a popular brand.

From a CHIRP technical view (and this live imagining stuff uses CHIRP), there are only 2 things that can improve resolution of a sounder.

Change the “speed of sound” in water and the other is change the bandwidth of the scanning “pulse” that’s sent out.

So any story about a new model transducer (and there is one in particular) producing improved resolution is something to be taken as a "confused claimed". Happy to show the scientific background negating the confusion.

There is one thing guaranteed about pushing this sort of technology into the rec fishing industry. The average fisho won't know enough to ask the right questions to help sort out the confusion that abounds.

The guys who should be able to help fishos are the retailers, experts, and gurus but can't. However, instead of saying "I don't know", they make up an answer.

And THAT'S where all the confusion comes from. Over-confident egos.

I’ve got it and I cart it around with me everywhere. I fish quite a lot and only target barra however I only use it maybe less than 5% of my time on the water. What I’ve discovered is I’m not a big fan of it and how it changed my days on the water. People say it’s a game change, and it is, but I don’t think it has enhanced the overall fishing experience for me. I understand its appeal and acknowledge the benefits it brings and I will continue to carry it around with me but at the moment I’m happy to pursue the hunt using the more traditional methods. Just a few thoughts!

Have found to be very useful tool like any sounder if paying attention to the fish and data being received. Don't use it much in harbour as the fish move about to frequently but use it in big rivers and shoal bay mainly on neaps and building tides with good success. Biggest mistakes I hear and see is people not watching how the fish behave to each cast/lure etc then also remembering it's a tool and not going to guarantee fish. I grinded a bit initially when I put it on my boat early in the year but since runoff to now have got double digit of 90s and one metre fish. Not counting anything smaller than the 90s. Even during our coldest peak in dry season I managed a 99 with 13 degree air temp at night. Have been finding retrieved in larger tidal movement and dirtier water can be more aggressive but neaps having to slow it right down and present on their noses. Still sticking to matching the profile of bait they are predating on and depth is critical. I think people also forget when water is a bit dirtier their vision isn't as great. For example I had a mate who's lure ended up being 12 foot away from fish he cast at and he was still winding it in like it was being followed when water clarity was only good to see less than a foot deep that with the bigger tides I mentioned contrast and louder lures helps but also needs to be close enough for fishes lateral lines to pick up. They seem to hear surface lures a lot further away compared to diving hardbodies no matter water clarity. But also showed him when we are scanning 20m and the fish return looks like 1cm on the screen having the smallest gap between fish return and lure means a fair distance from the fish and in bigger tides the fish may not even sense the lure. I find when the lure blends with the fish your lure tends to be close enough. Next is depth a lot of people struggle on scout/perspective mode to judge depth of lure but i just try to match the return of the fish. If fish is duller it's deep, if it's brighter it's higher in water column and when they are high and really active they look clearly like a Barra. But people also miss a lot of the active fish that are deeper dismissing them as bait etc. An example I had a couple of trips where the Barra were boofing but would not commit to any form of surface lures but were demolishing b52 wound slow enough to keep it in first 20cm of water but fast enough to wobble so they could track it. Also, excessive twitching seems to scare them unless they are really really hungry. I am finding a slow roll at eye level past their nose to get them interested and something as simple as a retrieve speed change will trigger the bite. Hardbodies I have been floating right above their head then a slow retrieve either across their face or away just enough to get lure diving to eye level gets the bite most times. Noticing fish showing up like rice grains are not active even the deep ones if sitting still but active you can make out they are head up slightly. Targetting the active fish makes it easier but getting bites from sulking fish is rewarding also. The most standout things it has taught me is below.

-retrieving your lure directly front on to their face is hit or miss.
-a lure retrieved from a 45 degree angle from the face but coming from behind gets a lot of bites
- retrieving a lure perpendicular to their face is also hit and miss.
-unless feeding aggressively lure will need to be presented with under a foot from their face.
- somedays they want twitching other days they want the lure stalled on their face for long periods and others slow rolled. Each trip changes and had their moods change during a day.

Cheers
Gibbsy

Here are some photos of results and how the Barra will actually eat when presented correctly. These fish were sitting deep and both caught in the middle of dry season but downed 5-7inch plastics. The b52 has had hooks replaced due to opening up trebles and is less than a year old.the sounder pic shows two large Barra around the 90s sitting quite deep but not really active heads were horizontal and they were not on the move.

One other notable thing I have learnt is alot of the time especially on fish sitting higher in the water column you need to cast a few metres past fish and intercept landing a lure a metre out tends to spook them.

Cheers
Gibbsy

Thank you for that Gibbsy. Quite a bit to digest there but looking forward to doing so. The thoughts about angle of lure retrieve to face of fish. Is that an observation gained from Active Target?

My Initial reaction is that there's a lot more than animated sonar in amongst that. Happy to talk about the other subjects. Take a couple of days to sort through your input.

Hey ronje,

Previously sight casting flats for Barra I never picked up on lure angle except for casting pressure points and current lines example. Bring lure with current naturally not against it works better for me. Since using active and watching the Barras behaviour and conversing with a heap of other mates that use active and consistently get bags of fish in 90s per trip with odd metre fish. They have confirmed that 45 degree angle is a top pick for the fish for some reason. The benefit of being able to watch the Barras behaviour with everything you do from the moment your lure lands is great knowledge but I firmly believe too many people out there with similar sounder setups don't absorb this info which is reflected in their catch rates. See before I had active I would fish for Barra all year round even when weather, moon, tide were not ideal just to work their behavioural patterns and movements out. Not just fish when they are active. Doing this for years resulted in consistent catches and literally being able to determine what time of tide and where I needed to be each day. The same goes with active over these past four months I have landed 11 in the 90s and 1 at a metre throughout our coldest times and season change. Each trip resulted on average a loss of between 2-4 fish. All of this in a fairly high pressured area 10-15mins from the ramp. Throughout same period I had heard of five people fishing same area stating there are heaps of fish but they won't eat. Mind you I was grinding and doing 12-15hour days to work out bite windows etc.

I will draw up the angles we have noticed works and doesn't a bit later today and send through. But just like reading sides can and downs can seeing the fish on the sounder is the easy but, being able to assess that information and convert is the harder task.

Cheers
Gibbsy

Cheers Gibbsy, agree with everything you wrote. They definitely come in from further away on the fizzers but the hookup rate is atrocious

Hey Jack,

Yeah I find the same I run 3 split rings nowadays with all my surface lures to help with hook up rate still miss a bit but alot better than factory setup.