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View Full Version : Depth Finders and your $$$



VietVet68
04-02-2005, 07:15 PM
Lowrance/Eagle, Humminbird, or Garmin?
You can research these at each manufactures site, and each will tout their's as being the best. But if you want to cut to the chase go to this URL with an open mind. This is the best unbiased article I have ever read. If someone knows of a better unbiased article please let us all know.
Please pay particular attention to Power, Resolution, and how wide a 20 deg. cone angle really is. (up to 60 deg.)

http://www.bassdozer.com/articles/crawford/depthfinders.shtml

Barnacle Bill
04-02-2005, 07:39 PM
What do you mean "how wide a 20 deg cone really is"? If you are talking about actual area covered, it is approximately 1/3 the depth with a 20 deg cone.

VietVet68
04-02-2005, 08:16 PM
What do you mean "how wide a 20 deg cone really is"? If you are talking about actual area covered, it is approximately 1/3 the depth with a 20 deg cone.
With the early flashers/recorders that was pretty much true, then it went to roughly half the depth was the diameter of coverage, now it has gone to:

"Lowrance and Eagle units come with a standard 20 degree cone angle, 192 Khz transducer. When combined with their Advanced Signal Processing, (filtering, Pulse Width Modulation, with Gain and Level equalization), they claim they will pick up cover and fish at 60 degrees or more."

I can only go by what I read.

Barnacle Bill
04-02-2005, 08:45 PM
I think I see where you are going with this. 20 deg is 20 deg and no amount of electronics is going to change the area covered (basic math). Lowrance makes one model (X-135 I think) that has a 60 deg xducer which gives you much more coverage. There are some others that use 3 - 20 deg xducers in one small module. They apply their advanced electronics and presto, you have a wide view representing 60 deg of coverage. With today's electronics I don't think there is many limitations as to what they can do. Except confuse us normal people. My new trolling motor has 5 built in transducers but I'm not sure how many of them apply to the sonar. I'm still trying to figure that out.

Moose1am
04-02-2005, 11:26 PM
Check out the thread called "What the heck do I need this for" or "What the heck do we need this for". That is where I worked my tail off trying to explain some of the depth sounder physics in here.


I spent an entire day producing graphics and discriptions of how sonar works and how to interupt the sonar displayes. Did you guys skip over that multipage post that I did about two or three months ago?

Obviously it didn't compute with some of you or you missed the thread entirely.

Do a search on Depth Sounders and or Depth Finders and pull up the post that I wrote. There were about six different post each with graphics to help explain exactly what Pulse Width and other terms mean.

Short pulse widths help you discriminate fish from the bottom. The shorter the puluse width the closer the fish can be hugging the bottom and still be discurned from the bottom. I showed a graphic in Three different dimentions on the actual shape of the sound waves that are produced from the transducer. I explained how you can increase the EFFECTIVE cone angle by turning up the gain and then you can decrease the EFFECTIVE cone angle by turning down the gain. Note that I captilized the word EFFECTIVE as that is what is meant by a 20 deg cone angle. Others posted in that thread about db and the meaning of the cone angle. These cones don't look like the Egyptian Pyramids guys. Waves don't travel in straight lines but bend somewhat.

And if you have five different transducers built into your sonar then you have five diffent transducers sending sound waves out in five different directions that overlap. Have you heard about phased Array Radar units? Basically similar to the phased array sound wave that come out of the transducer made by humminbird.

I got all this basic information out of a 1976 Fishing Fact Magazine that covered all you need to know about how sonar works in fishing gear. And before Fatboy has another heart attack just remember that certain things in the world of PHYSIC never change. So what was true in 1976 is still true in 2005. We don't need to reinvent the way that sound waves propogage though the water again.

Todays transducers are multiphased and can send out waves in many direction in very rapid succession. Phased array is the term that best describes how that works.

An array is just a series of columns and rows. Anyone that took basic computer programming should understand the term array. Any math major should understand the term array. When you see a band on the football field standing in neat rows and columns making a square array then you know what an array looks like. Evenly spaced columns and rows. That is how you get wide angle coverage. You use more than one cone angle and put them all together to produce an image. Ever seen them using a ultrascan on TV. They are moving the transducer around over a womans body to get different angles of the baby. The ultrasound tech is manually moving the transducer around over the womans stomach to get different sonic views of the baby inside. Well the computer can be used to automatically alter the direction of the sound waves in modern transducers these days. The computer does this in phases. Therefore they call it a phased array.

http://www.crappie.com/gr8vb3/attachment.php?attachmentid=614



I think I see where you are going with this. 20 deg is 20 deg and no amount of electronics is going to change the area covered (basic math). Lowrance makes one model (X-135 I think) that has a 60 deg xducer which gives you much more coverage. There are some others that use 3 - 20 deg xducers in one small module. They apply their advanced electronics and presto, you have a wide view representing 60 deg of coverage. With today's electronics I don't think there is many limitations as to what they can do. Except confuse us normal people. My new trolling motor has 5 built in transducers but I'm not sure how many of them apply to the sonar. I'm still trying to figure that out.

Barnacle Bill
04-02-2005, 11:57 PM
I think that was what I was trying to say, well at least part of it. You just got a better way with words than me. Thanks Moose.

VietVet68
04-03-2005, 01:38 AM
Check out the thread called "What the heck do I need this for" or "What the heck do we need this for". That is where I worked my tail off trying to explain some of the depth sounder physics in here.
Moose, I have read your post and entire thread about "What the heck...."
You did an excellent job!

The only reason I started this thread was because I had read several other threads that did not seem to be much help to the first time buyer as far as the value of the different features now available. I probably should not even have mentioned the 20 deg./60 deg. thingy, but my mind had drifted off into the days of my old Lowrance Mach I. My opinion is/was that back in that era turning up your gain/sensitivity to increase your view area was not really a very good option unless you wanted to see 10' of "surface clutter" or wanted to check the timing on your main kicker.:)

I am under the opinion that with todays technology and sensitivity adjustment capabilities the reasonable viewable area has almost doubled. Please note, I did not say "cone angle". But I would also agree that anything outside the cone angle will not show as strong as anything within.

I thought the Humminbird/Lowrance article was good for the fact that it compared features and gave more insight to the features and not the brands. If you noticed it was written in 1997, imagine the technology we have today.

unknown 5
04-03-2005, 06:52 AM
My Hummingbird Matris 37 is supposed to have a 90 degree cone angle and is supposed to use a quadrabeam transducer which I will assume means it throws out 4 different beams that together covers a 90 degree area. Some of this gets too technical for me but I know I like my outfit and I am certainly finding fish with it. Now, if I can get them to bite!

DENNIS BOWERS
04-03-2005, 07:22 AM
Redtick-i Have The Same Unit And Thats Exactly What I Took Quardabeam To Mean! Oh Well I Too Like Mine And Find Fish With It--maybe They Will Have An Update To Catch Em???just Bought The Gps For Mine,gonna Hook It Up Today!!good Fishin To Ya!!dennis

unknown 5
04-03-2005, 06:29 PM
Please let me know about your GPS accessory. I got the free barometric sensor but I was going to wait to see which GPS outfit I want to use and then daisy chain them into my unit. If the Hummingbird unit works OK, I may just go with it and get a completely different unit to hunt with. From what I understand, a GPS unit manufactured by another company can be hooked into it also.

whizkids
04-03-2005, 07:45 PM
My Hummingbird Matris 37 is supposed to have a 90 degree cone angle and is supposed to use a quadrabeam transducer which I will assume means it throws out 4 different beams that together covers a 90 degree area. Some of this gets too technical for me but I know I like my outfit and I am certainly finding fish with it. Now, if I can get them to bite!-----------------------------------------------------------------------------------------
Now, if I can get them to bite.------------------------------------------------------------------------------------------------------------------------------
Maybe they are quadrabeam generated fish and you need a quadrabeam defragenator to get them to bite. - I have read all Moose post and all the other post and explaining this stuff. I have owned an electronic marine product since the advent of the battery powered little green box. I believe a flasher unit and I believe a paper graph. I have an X97 and I use it to see the bottom. I don't believe what if shows on fish ID and I don't know what it is showing in automatic mode. I will not take the time to use it in manuel mode where I can adjust things and determine whether it is weeds, fish, rocks,bait school or a tree. I do like the speed indicator feature and temp gauge.
How many post have included the words " I don't know how " or very similar words.
The high tech stuff and now in technicolor is used to catch the big fish that has the bucks. They do a real effective job. GPS features are a different issue. I think they are wonderful.
Most fishermen would catch more fish by buying a flasher unit and spending the difference on lures, rods, etc.

DENNIS BOWERS
04-04-2005, 05:48 AM
REDTICK...GOT THE GPS HOOKED UP YESTERDAY, IT SEEMS TO BE WORKING, GONNA PUT THE BOAT BACK IN THE WATER THIS AFTERNOON AN PUT IT TO THE TEST!!ITS GOT ALL KINDS OF DIFFERENT SCREENS ON IT,TAKE AWHILE TO FIGURE IT OUT!! BASS PRO HAS THEM ON SALE FOR $99--ABOUT $25 CHEAPER THEN HUMMINBIRD!!ITS GOT A Y CABLE TO HOOK UP ACCESORYS.GOOD FISHIN TO YA!!DENNIS{i 'll let ya know tonight how it worked}

unknown 5
04-04-2005, 06:09 AM
Dennis, I am VERY interested.

Stinkfinger
04-04-2005, 07:45 AM
I have a question:

Why can't your depth finder work like a radar screen and show the fish swimming in from the appropriate direction instead of a constantly scrolling pattern that gives only the depth of the fish?
(my knowledge of depth finders is only eclipsed by my knowledge of the female mind)

javelin389
04-05-2005, 05:16 PM
I also have a matrix 37 and ended up going with a transom mount where did you other guys mount your transducers.

TAE73
04-05-2005, 05:52 PM
I put mine on the trolling motor, I have a flasher for when I am running the big motor that has a built in temp gauge. Just so you know you can use the transducer that came with it on the trolling motor. It will work by using a automotive hose clamp. I have never bought a trolling motor transducer and have always used this method. I have yet to have any problems doing so. The reason why I like it on the front, is I use it in the split screen with it showing the bottom screen looking down and then top showing typical side view. The top looking down shows to which side the brushpile or fish are according to you location. I am considering buying another 37 for the back of the boat. Also like the looks of the 67 or 97's just dont like the price.

AlanC
04-05-2005, 11:58 PM
I have a question:

Why can't your depth finder work like a radar screen and show the fish swimming in from the appropriate direction instead of a constantly scrolling pattern that gives only the depth of the fish?


Someone on another fishing board recently mentioned these:

http://interphase.psicompany.com/seascout.htm

DENNIS BOWERS
04-06-2005, 05:58 AM
Redtick, Gps Is Working Real Good.figured Out How To Leave Crumb Trail,an How To Mark Hotspots! I Think When I Get It All Figured Out I"ll Like It Even More!! The Only Thing Is At Hi Speed My Depth Is Goin Nuts?? Javelin--mine Too Is Mounted On The Transom, Got A Small Humminbird Monted To Trollin Motor.havent Had Any Interferance Problems With Them. Good Fishin To Ya!!!dennis

CatFan
04-06-2005, 09:11 AM
Mr. Crawford totally misunderstands the way a depthfinder works. He confuses the concept of the transducer frequency and the pulse repetition rate of the unit. The entire paragraph about frequency is almost incoherent. Frequency is important primarily because water, especially saltwater, attenuates high frequencies more than low frequencies, hence the 50KHz transducers for offshore use vs. the 192 or 200KHz transducers for freshwater.
His comment about power being overrated is correct. Most people who fish freshwater have plenty of power in any unit on the market.
He never discusses sensitivity, which is a critical point. It is what determines whether you see weeds or not. He attributes this to frequency.
If you want a good description of how sonar works, go to Lowrance's web site and read the sonar tutorial. Most of it applies to any unit, and it's pretty good.

Moose1am
04-06-2005, 12:10 PM
Wow. I am glad that you read it. I was just kidding as some of my good friends in here were kidding me about my NOVELS. LOL


I don't mind your post at all. I am glad that you could add to the subject for the new guys. Thanks for helping. I like the spirt of this group as we all tend to try to teach and help others and that in my opinon is a very good thing.

Keep up the good work mate.



Moose, I have read your post and entire thread about "What the heck...."
You did an excellent job!

The only reason I started this thread was because I had read several other threads that did not seem to be much help to the first time buyer as far as the value of the different features now available. I probably should not even have mentioned the 20 deg./60 deg. thingy, but my mind had drifted off into the days of my old Lowrance Mach I. My opinion is/was that back in that era turning up your gain/sensitivity to increase your view area was not really a very good option unless you wanted to see 10' of "surface clutter" or wanted to check the timing on your main kicker.:)

I am under the opinion that with todays technology and sensitivity adjustment capabilities the reasonable viewable area has almost doubled. Please note, I did not say "cone angle". But I would also agree that anything outside the cone angle will not show as strong as anything within.

I thought the Humminbird/Lowrance article was good for the fact that it compared features and gave more insight to the features and not the brands. If you noticed it was written in 1997, imagine the technology we have today.

Moose1am
04-06-2005, 12:20 PM
High speed travel can create turbulence around the transducer mounted at the rear of the boat on the transom. Next time you are out on the lake with a friend have him crawl to the back of the boat (wearing a life vest ) and look at the water flowing off the back end of your boat while you are underway at relative high speed. Tie him on the boat if necessary so he won't fall out. LOL or have him water skie barefoot and observe the boat from about 10ft away at the back. :) JK. Point is this... the transducer should be mounted in a LAMINAR flow of water at the transom or mounted inside the boat. One thing you might consider is lowering the bottom of the transducer a little deeper into the water. That may make it work better but then you run the risk of hitting something with that transducer as it will be lower than the boat's bottom. Play with the transducers location and also check to make sure that no other electronic equimpent is creating EMF interference into the transducer's cabling.

Most likely the problem is air bubbles or cavitation in the water at the face of the transducer. Remember that sound travels though water differently that though air. And the computer's timing of the sound waves is set up to for water travel not sound traveling though air bubbles. Sound travels though water much faster than though air. And the timing is in Microseconds when you are going very fast and the water is deep. Pluse width becomes a critical factor along with the amount of Sound Pressure that is created with each pulse of sound. Pulse width is the time between each sound pulse that it being transmitted out of the transducer. There used to have to be some delay in Milliseconds to let the first pulse go down hit the bottom and then bounce back up to the transducer to be recorded before the transducer sent out the next sound pulse. Think of those old WWII submarine movies with the sonar pinging away from the destroyer. Remember as the destroyer got closer to the submarine the pluse width got shorter. Ping.............. Ping..............ping......ping.... ping...ping..ping..ping.ping


Redtick, Gps Is Working Real Good.figured Out How To Leave Crumb Trail,an How To Mark Hotspots! I Think When I Get It All Figured Out I"ll Like It Even More!! The Only Thing Is At Hi Speed My Depth Is Goin Nuts?? Javelin--mine Too Is Mounted On The Transom, Got A Small Humminbird Monted To Trollin Motor.havent Had Any Interferance Problems With Them. Good Fishin To Ya!!!dennis

Moose1am
04-07-2005, 03:39 AM
My first fish finder or depth sounder was the Lowrance Little Green Box. It used two 6 volt DC dry cell batteries and worked very well.

Today Humminbird has introduce SideScanning Sonar to the fishermen for only a mear $2000.00. Now with this feature you can see a submerged swimming pool as if you had X ray vision and could see thought the water.

Check out the new 2005 Humminbird Online Catalog at www.hummingbird.com (http://www.hummingbird.com) and you will be absolutely amazed at how far the technology has come since 1966 when Lowrance first introduce the "Little Green Box"

Todays transducers can see in all directions at almost the same time. They update the scans at a rate of 40 times per second. Now that is fast. Not only can they send out a pulse 40 times each second but they can focus the sound pulse in different directions to cover a wider field of view. Cone angles don't change but the number of cones used is increased dramatically. Multicones are being used to show more of the bottom at one time




-----------------------------------------------------------------------------------------
Now, if I can get them to bite.------------------------------------------------------------------------------------------------------------------------------
Maybe they are quadrabeam generated fish and you need a quadrabeam defragenator to get them to bite. - I have read all Moose post and all the other post and explaining this stuff. I have owned an electronic marine product since the advent of the battery powered little green box. I believe a flasher unit and I believe a paper graph. I have an X97 and I use it to see the bottom. I don't believe what if shows on fish ID and I don't know what it is showing in automatic mode. I will not take the time to use it in manuel mode where I can adjust things and determine whether it is weeds, fish, rocks,bait school or a tree. I do like the speed indicator feature and temp gauge.
How many post have included the words " I don't know how " or very similar words.
The high tech stuff and now in technicolor is used to catch the big fish that has the bucks. They do a real effective job. GPS features are a different issue. I think they are wonderful.
Most fishermen would catch more fish by buying a flasher unit and spending the difference on lures, rods, etc.

Bigcrappster
04-18-2005, 02:12 PM
Folks,

I'm not having trouble seeing fish on my depthfinder, it's the catching them that is presenting me with trouble!

bigcrappster