Depth Finders and your $$$

[VietVet68]

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/cr...hfinders.shtml

[Barnacle Bill]

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]

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]

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]

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.

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]

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]

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]

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]

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]

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.