As promised.
I was unsure of what level to pitch this at initially. Then thought that the fundamentals are important 'cos everything follows from that. Forgive me if too basic for some but a little revision won't hurt.
Attachment 121236
Bit meatier
I've tried to keep the technical stuff to a minimum. It won't get any more technical than this.
Need a bit of f/back if its too deep etc.
Can sure see the irony where a term (resolution) is used by the industry to describe 3 different things. No wonder it's become confusing.
Attachment 121237
Can't wait for the explanation of " side scan ", forward scan and 3D mapping
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Make sure that you are au fait with the 2 things that I've put up particularly with the bit about range resolution where we're dealing with a sounders ability to distinguish between targets. In the case of the usual technology we're talking about single pulse sounders.
I commented on the catch 22 situation that single pulse sounders left us with in trying to do that and spoke about new technology.
We're going to be looking at that new technology next. Its called CHIRP and haven't the manufacturers been playing fast and loose with it.
Side scan is pretty straight forward but what do you understand by "forward scan", Phill? Make sure we're on the same page.
Haven't had much to do with 3d mapping although I've used it to give a 3d diagrams of the bathymetrics of Yeppen Lagoon here on the southern outskirts of Rocky near the big bull roundabout. Lagoon on the left as you enter the southern outskirts of Rocky. That lagoon is 11 metres deep. I'll dig up the map.
" If you want a sounder to give you accurate reliable information, you must have high resolution in the pixel count. At least 480 or better."
Not at all. People - a lot of them commercial fisherman, have quite successfully for a lot of years, been catching a lot of fish with sounders that had pixels the size of lego blocks in comparison to todays high res screens. It all comes down to being able to drive your sounder effectively and time on the water. In at least one situation I know of, the advancement of screen technology meant the loss of a particular type of bottom echo that was relied upon by W.A. based cray fisherman to the point we had "legacy software" written by the Japanese engineers so the new units could read the same way the older ones did. Screen resolution can certainly allow a smoother, more detailed picture and if the target resolution allows it, individual fish echos to a much smaller size I agree, but to say you "must" have it is nothing more than an advertising blurb.
I have an auto button that draws little fish pictures.
to say you "must" have it is nothing more than an advertising blurb.
How do you arrive at that conclusion, scottar? Advertising what? Larger screens?
If one only wants to see the type of bottom, then screen resolution indeed doesn't matter much. Its a big target and hard to miss.
But if you want to see detailed info, then decent screen resolution is one of the 3 important features that you need.
Screen resolution is dependent on the number of pixels that the screen is capable of displaying (esp vertically considering the main measure is depth - a vertical measurement).
Insufficient pixels and the screen image will appear a bit "blocky", more pixels and the blocks are smaller showing more detail and even more pixels again yield even more detail.
The bottom line is that if you want to see as much detail as possible (which is what recreational guys want - including me), then it doesn't matter what types of processing smarts you have in the device, you must indeed have the screen resolution or you won't be able to see the detail you are expecting. Without it, you're not going to get what you want from the device and are wasting your money.
Smaller screens are a performance compromise to suit different purchaser budgets.
Its like buying a car, scottar.
What performance, luxury, safety, economy and look you are seeking is determined by your budget. You won't get the luxury out of a Hyundai, the economy out of a V8, performance out of a 2 litre engined vehicle, safety out of a small car or look from a mass-produced one. So you compromise on some features.
But there are some essential features that you need to take more note of than others.
In respect of sounders, the number of vertical pixels in the screen is one of those essential features.
Its the screen that is going to be used the most as that's what's delivering the results to your brain via your eyes (not the controls adjusting depth, width, sensitivity etc).
Prospective purchasers/users of sounders are battered from pillar to post with heaps of misinformation and flounder trying to sort things out.
They don't want to hear how complicated things are or how many or what types of exceptions exist. They simply want to get things sorted enough to get a handle on things and can then find their own way of making it work best for them. Bit like your cray fishermen, I guess Scottar. A "one-size-fits-all" approach didn't work for them so a workaround was arrived at.
People want to over-complicate things by quoting "exceptions". That's human nature, I guess.
Anyway, I think I'll stick to blurb that advertises vertical pixel count (bigger screens).
I currently use a 10 inch screen but it wasn't that long ago that I was using a 5 inch (from memory) screen on one of the first CHIRP recreational sounders available from Raymarine (to have a look at the effect of CHIRP technology ) and there is a big difference in screen resolution between 5'" and 10".
Meanwhile, those who want to, see what u can find out about the origins of this CHIRP stuff.
CHIRP is the one of the more significant relatively recent additions to sounder technology as was "broad band" terminology.
All the manufacturers were at it. Broadband this, broadband that, chirp this, chirp that. Chirp and broadband do have a connection but I'll defy anybody to explain what its all about and how it works. I've come across a couple of people who can tell me what it brings to the table but not how or why.
I just refer to it as a "jesus box" for simplicity (no disrespect intended to anybody).
If I told you that chirp was around the place in 1912, would that surprise you? As we all know, 1912 was the year that the Titanic struck an iceberg. The rest is history so to speak.
Titanic attempted to communicate by morse code to other ships but none were in range except 1. The wireless operator on that vessel had simply turned his ship's wireless off.
That morse code installation had a fault that clearly identified the ship without the need for the operator to say who it was.
Had that wireless been on, the story of the Titanic would have been a whole lot different.
Anyway, subsequent enquiries about the tragedy were centred around the identity of the ship that could have so easily assisted the Titanic had it known what was unfolding but didn't.
The key to identification of that ship in 1912 was............chirp. Yep, everything old is new again.
Have a pressing matter that's suddenly cropped up here, so will be back overnight. Sorry.
"How do you arrive at that conclusion, scottar? Advertising what? Larger screens?"
Besides the fact it was basically the catch cry in every advertising campaign form Humminbird and Lowrance during their head to head product development wars 15-20 years ago, a pretty successful 20 year career - selling, installing, setting up, using and servicing pretty much every major brand and quite a few minor ones.
Larger screens - or higher resolution. Take for example your 5 inch Raymarine with a vertical pixel count of 480 or a similar sized Lowrance and then compare it to a JRC FF50 with a vertical pixel count of a mere 320 - on a 6.5 inch screen. One market place - shallow water will prefer the Raymarine because of its features. In a different market place - offshore fishing, the FF50 would have arguably been the countries number one selling unit at one time because it had features that were pertinent to it's target market, it was simple to operate and it worked - even though there were higher resolution offerings available from other manufacturers. Same can be said of the FCV range of Furuno offerings from the arrival of the 625/585 variations onwards.
I get what you are saying but the bottom line - if your sounders transmitter, receiver, transducer and processing can't display what you want to see - all the pixels in the world will not help. That's the issue with approaching sounders "by the numbers". There are some pretty impressive numbers out there but unfortunately, much along the lines of a pretty famous TV commercial - "Sounders ain't sounders".
I sold the odd sounder in my career. What most wanted was a unit that was easy to use, showed them what they needed to see and was reliable. For a lot of guys, they simply don't need to be able to count how many individual fish are in a school - sure the pictures look cool but at the end of the day, by using a zoom or shift facility they got all the detail they require. Certainly for some types of fishing - shallow, calm water using the later gen sidescan units that actually have the capability to return echos that can be processed into near photographic quality images, resolution is of the utmost importance but for others the biggest things are the sounders ability to return noise free images at speed or sheer deep water capabilities.Complicate things by quoting exceptions - every different type of fishing is to an extent an exception. One sounder no matter how high the resolution, will not suit all and some sounders with "inferior" screen resolution did / do a much better job of some applications. If two separate fisherman came to me asking for a sounder, the first question they would be asked is "for what type of fishing", the second was "on what type of boat" and the third was "at what type of budget. The recommendations were very different dependant on the response to the first question in particular.
Scottar
I'll send you a message where you can have a urinating contest (if that's what you want) without disrupting the guys who want to find out about things, maybe?
Now we know that the principle of chirp has been around for years and years.
Morse code chirp (warbling code characters) was caused by the morse code tones changing frequency (therefore what the tone sounded like) every time the transmit key was pressed. The result was that the transmission sounded like a canary warbling or chirping.
Yep, birds chirping. THAT'S the principle behind recreational chirp sounders. That's one you can use on trivia nights.
Wind forward 30 years from the Titanic to WW2 and the infancy of operational radar.
WW2 (and later) military radar researchers found that while they might be able to see a reflected signal, they didn't know if they were looking at 1 enemy aircraft or several.
They needed a way to improve resolution and found that by changing the frequency of the radar pulse as it was sent out, they could achieve that. Success but that military success was immediately classified for military use.
Like every research project that military researchers get involved in, this project had to have a name.
Radar research had more priority (and funding) than submarine research, so the radar guys got naming rights.
A name related to changing (sweeping) of frequencies in use already existed (from morse code days) for that type of thing. Chirp.
Having a name already , suitably impressive-sounding words were cobbled together starting with the the first letter of each word. Back -to- front acronym construction.
Compressed high intensity radar pulse. Compressed high intensity radiated pulse. Compressed high impact radar/radiated pulse. Take your pick of which one you think is correct as they all sound technically impressive but ALL the letters still spell CHIRP.
Only in the 50s was the breakthrough de-classified and work began on the principle for civilian use.
That's the history behind your chirp sounder.
Everything old is new again.
Back again with the next step - Chirp technology.
We all know abouit chirp by now. Don't we?
Anyway, I can't move on without talking about Lowrance.
Lowrance is a US based manufacturer who caters for the US east coast (Atlantic) and west coast (Pacific) markets. Deep water stuff.
So their chirp innovations are concentrated on deep water applications. That means lower freqs. Hence we see them them focusing on 50khz, 83 khz and the highest effective deeper water frequency 200 khz.
So that's what they did and mainly in the commercial market.
In Aus we don't normally see anything like the depths that require those frequencies.
We're basically "shallow water" uses of sounders.
Humminbird, Garmin and Raymarine (plus others) focused more on the shallow water users.
Aus is lucky that that shallow water users in the US included the "bass brigade" in dams, impoundments, rivers, creeks and other shallow environments.
So there was a fair US market for shallow water sounders.
That means standard higher frequencies like 455khz, 800 khz and 1200 khz (Mega). Raymarine had their own shallow water frequency of 360khz.
To maintain a place in that market, Lowrance advertised broadband technology, CHIRP technology etc but really only paid lip service to that by only putting CHIRP on their deep water market (50 khz, 83 khz and 200 khz).
Even their comprise to appease the US shallow water bass brigade stopped at 800 khz (last time I looked) so their sidescan stuff isn't chirp so doesn't have the ability to distinguish between targets like most of the others. Don't think that their structure scan feature uses chirp either. Happy to be corrected about that.
Then to add insult to injury they called 200khz CHIRP High Chirp. High my foot!
Anyway, here's the next edition.
Attachment 121250
No pissing contest required. You asked how, I answered. There is no way to put experience into a quantifiable numerical answer and regardless - like I posted, numbers don't make a sounder. Don't bother with the PM.
Your Lowrance post - you may have been given a bum steer as to the companies history I'm afraid. Up until chirp came about Lowrance wouldn't have known a deep water sounder if you belted the MD of the company about the head with it. They had been chasing the Japanese and Simrad in the race for deep water performance for like - ever.Lowrance's parent and main US market was the bass fishery - why - that's where the money was.Navico - the investment company that now owns Lowrance, killed off one of the better deep water sets when they purchased Simrad and "Lowranced" the sounder component. Compared to them back then we were a deep water fishery predominantly - at least those that bothered with sounders. They were years behind in even introducing 50KHz as a frequency and even then you only got it if you purchased a separate (and somewhat expensive transducer). All their earlier offerings were 192Khz and used cone angles that made any sort of definition beyond 50 metres near on non existent. They even manufactured a "3D" model that was a dismal flop at 192KHz using a 6 beam transducer - in a direct response to Humminbird doing it first. They also struggled in the deep water markets because as the rest of the world went to colour and the inherent echo return strength differentiation it provides, Lowrance chose to stick with LCD on the grounds of being water proof (ish).
It was well down the road - long after some of the Japanese manufacturers, that Lowrance, with the availability of cheaper Colour LCD displays, went to colour and at the same time someone in marketing made the decision to go to more traditional frequencies - probably to allow them to utilise Airmar's range of transducer options and give them transducers alongside their own, that could provide deeper range capability.
It was Airmar's chirp transducer development that has driven the sounder manufacturers push into chirp for a traditional 2D picture. For some of the manufacturers it has provided a cost effective way to finally attempt to challenge the Japanese in the deep water race.
Geez, a "negative nancy" ego that wants to argue about every bloody thing. I can't see him any more now so he's disrupting you guys only.
Got some more for ya to think about.
A screenshot from yesterday.
Note the speed across the bottom at .3kmh. That was at electric anchor.
However, speed through the water was more than that because of pretty high tidal run (about 3-4kmh). Fish were travelling WITH the run so they were going through the beams at about my normal searching mode. THAT'S why not much elongation of the image. You get elongation of image when boat still and fish moving through beams slowly therefore taking longer to pass (so they appear elongated).
If you're sitting above a school with little relative movement between boat and school, it looks like spaghetti junction.
Saw a image not so long ago of a elongated image under a guys boat at anchor. He thought it was croc but it was simply a long fish being made to appear even longer by the slow movement. You won't mistake a croc under the boat.
What I'd like to capture on a sidescan image is a Fitzroy R dolphin (special type apparently).
These 3 images are all CHIRP. You can tell that by the little frequency boxes in the bottom left hand corner.
175 - 220 , 780 - 860 and 1150 -1275 means that each image is being swept across a range of frequencies. 45khz sweep centred around approx 200khz, 80khz sweep centred around approx 800khz and 125 khz sweep centred around approx 1200 khz respectively.
Sweep frequencies mean its a CHIRP image.
Anyway, top is sidescan, bottom right is downview and bottom left is normal sonar.
Still got a bit of fiddling to do with "knob" settings since software upgrade (as you can see from the straight "sonar" view - bottom LHS).
Today's job in town reach. More king have arrived since the other day so should be plenty of targets available.
Attachment 121252
Your writing the stuff that's being questioned Ron if you can't hack it move on.Originally Posted by Ronje1
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