You are logged in as a guest. ( Logon | Register Now! )



Sticky A fire drill with Sonar, Down images.....(Pic Heavy)
Jump to page : 1 2 3 4
Now viewing page 2
   Fishing Sonar, GPS and Marine Electronics

Posted by nwright
8/4/2010 5:56 AM
"So if you want the most accurate GPS point of the structure/cover you are trying to fish vertically 200khz will get you the most accurate GPS waypoint... Hope that clarifies.. "

All you have to do is move your 2D cursor over the object (tree) you want to mark and save your waypoint. It doesn't matter which transducer you are using, the results will be the same As you move the cursor from your present boat position the GPS will add to or subtract from your present position to mark the waypoint.

In theory it would be easier to find and mark an object using a wider cone angle. Once located and a waypoint added, it would be better to vertical fish it with a narrow cone angle transducer. I would assume that is what you are trying to say.
Posted by Triton Mike
8/4/2010 7:06 AM
nwright, If you have two trees 30ft apart in 30ft of water and you go in between them. BOTH show up on your Sonar screen in 200/83 dual beam mode and NONE of them show up on the narrow 200/20 degree beam. How do you know which tree your marking the left one or the right one if they both show up on your sonar screen???? Technically, You can't tell left and right with SONAR alone with structure. Now with SI that's a different story move the cursor over to the structure and mark the way point and your done, but we are talking sonar here not SI. If you see the trees on the narrow 200khz/20 degree beam you cut your accuracy from a possible 15ft off on your waypoint to within 5ft in 30ft of water ie better accuracy.

nwright - 8/4/2010 5:56 AM

In theory it would be easier to find and mark an object using a wider cone angle. Once located and a waypoint added, it would be better to vertical fish it with a narrow cone angle transducer. I would assume that is what you are trying to say.


Not really. You are right to FIND the structure wide cone angle would be best. But from a waypoint accuracy standpoint. I would double back in the narrow beam and find the tree and key in on it for better accuracy. GPS points are only as accurate as how close you are to the structure being DIRECTLY under the boat. With wide beam the structure/tree CAN be off to the side as much as 15ft in 30ft of water. So if you follow your theory and mark the tree with the wide beam mode, you MIGHT not even see the structure on your narrow beam mode when you go to fish it because your tree can be off to the side of the boat. Now for some 15ft off is acceptable accuracy. But I look at it like this. If I am fishing a lay down with a bass in it and I cast 15ft to the side of the lay down the odds of me catching that bass aren't as good as if I casted 5ft from the lay down.

Take a look at these 2 images to compare the accuracy based on what you SEE on your sonar screen.. the RED X marks the way point based on the boat position (directly under the boat).. Technically the red x's should be directly where the boat is not on the lake bottom where I have it but just shows what I am saying to get my point across..


Both trees show up on sonar screen using wide beam (tree is a possible 15ft to the side of the boat). Neither tree shows up on narrow 20 degree beam..


Tree show up on narrow beam directly under the boat (within 5ft)..


Mike




Edited by Triton Mike 8/4/2010 8:04 AM
Posted by nwright
8/4/2010 6:50 PM
"So if you follow your theory and mark the tree with the wide beam mode, you MIGHT not even see the structure on your narrow beam mode when you go to fish it because your tree can be off to the side of the boat. Now for some 15ft off is acceptable accuracy."

Mike, I like the images you have posted and they could be helpful to a lot of people. I question some of the things you have posted at the risk of being called "Fishton"!! With a Lowrance 2D sonar I can mark any tree that shows up on an 83 or 200Khz by moving the cursor over any tree, save a waypoint and go back to it with the 20 degree transducer. I do not have to be directly over it to mark it. I works just like structurescan/sidescan. I have done this several times with as much accuracy as if I had been directly over it.
Posted by Triton Mike
8/4/2010 9:54 PM
nw, I have no problem with agreeing to disagree here. By all means if your system works for you then don't change a thing. I Hope your having a great summer season..

Mike
Posted by Doug V
8/5/2010 2:37 PM
Not wanting to start a war here but there are several things you have to consider. GPS Accuracy is controlled by the number of satellites and correction signals HDOP and EPE are values that state the accuracy level. But What Mike was trying to point out is marking a waypoint on 2D sonar screen and coverage area. THe smaller the coverage area the less area in each sonar ping or Column of Pixels. Remember a screen is made up of numerous pixels rows and columns. Columns are vertical and rows are horizontal. When the sonar pings it fills in the column with the data returned from a selected area. 20° is a smaller area of data being displayed versus 60° data. Like Mike has shown in the 2D illustrations. When you move the cursor over the point of interest you want to make in 2D Screen and with Humminbird you can mark the points of interest and it will mark anything being displayed on the 2D Screen. If running in the 20° Cone the waypoint is going to be more precise because of the smaller coverage area versus a wider cone for that Ping or Column of Pixels being displayed your marking the Column of the data not the area that was recorded by the sonar. So in 30 feet each column in 20° is recording 10' of bottom coverage and at 15' is only covering 5' on that same column of pixels or ping. With 60° that coverage goes to 30' of bottom and 15' of coverage.

The only way to tell in Traditional 2D Sonar where something is at by the strength of return but this mainly works on fish for each single ping of sonar. Unless you use something like Humminbirds Quadrabeam Sonar that covers to the right and left two seperate beams then you can tell which side. Same thing goes with Down Imaging and Side Imaging. DownImaging is blending of data from all directions. Side Imaging shows exactly which direction it is.

With Humminbird you can view the 20° and 60° data separately in a split screen and can mark data from either cone but you can't tell with that Column of Data if it was front, back, left or right of the transducer. So the only way to get more precision is with narrower cone angle. And with Humminbirds Switchfire Clear Mode this is even more precise because it does not listen for the weaker returns in the side lobes of sonar....

Clear as Mud???

Posted by nwright
8/5/2010 10:53 PM
Doug V - 8/5/2010 2:37 PM

Not wanting to start a war here but there are several things you have to consider. GPS Accuracy is controlled by the number of satellites and correction signals HDOP and EPE are values that state the accuracy level. But What Mike was trying to point out is marking a waypoint on 2D sonar screen and coverage area. THe smaller the coverage area the less area in each sonar ping or Column of Pixels. Remember a screen is made up of numerous pixels rows and columns. Columns are vertical and rows are horizontal. When the sonar pings it fills in the column with the data returned from a selected area. 20° is a smaller area of data being displayed versus 60° data. Like Mike has shown in the 2D illustrations. When you move the cursor over the point of interest you want to make in 2D Screen and with Humminbird you can mark the points of interest and it will mark anything being displayed on the 2D Screen. If running in the 20° Cone the waypoint is going to be more precise because of the smaller coverage area versus a wider cone for that Ping or Column of Pixels being displayed your marking the Column of the data not the area that was recorded by the sonar. So in 30 feet each column in 20° is recording 10' of bottom coverage and at 15' is only covering 5' on that same column of pixels or ping. With 60° that coverage goes to 30' of bottom and 15' of coverage.

The only way to tell in Traditional 2D Sonar where something is at by the strength of return but this mainly works on fish for each single ping of sonar. Unless you use something like Humminbirds Quadrabeam Sonar that covers to the right and left two seperate beams then you can tell which side. Same thing goes with Down Imaging and Side Imaging. DownImaging is blending of data from all directions. Side Imaging shows exactly which direction it is.

With Humminbird you can view the 20° and 60° data separately in a split screen and can mark data from either cone but you can't tell with that Column of Data if it was front, back, left or right of the transducer. So the only way to get more precision is with narrower cone angle. And with Humminbirds Switchfire Clear Mode this is even more precise because it does not listen for the weaker returns in the side lobes of sonar....

Clear as Mud???


Well Doug, I'm surprised it took you this long to respond to this since the two of you are in lock-step on BBC.

As for GPS accuracy I hope your unit is more accurate than the EPE numbers your unit displays. Typically, a GPS is much more accurate than the EPE.

Using the logic both of you are using then waypoints derived from sidescan objects are way off and you have a hard time locating them. I never have had a problem marking an object 30, 40, 50ft, etc from the boat and being able to navigate the boat back on top of it. As for where an object is in relation to the boat using 2D sonar, I could care less. I can move my cursor over that object to create a waypoint. I can then go back to that object without any problem. If I want to know at any time how far and what direction the waypoint is from the boat I can use the navigate feature. I use overlay data, distance to destination along with a steer arrow to provide that info. I then know in real time the distance I am from that object, in feet, at all times.

I have enjoyed the exchange.
Posted by Doug V
8/6/2010 10:16 AM
Thanks for the kind comments...I'm here to help others learn and how to use all the feature of their Humminbirds But concerned your posts are contradicting yourself. Because you are telling that you can Mark Objects in 2D Sonar and that is what the subject has been on

nwright - 8/4/2010 6:50 PM

" With a Lowrance 2D sonar I can mark any tree that shows up on an 83 or 200Khz by moving the cursor over any tree, save a waypoint and go back to it with the 20 degree transducer. I do not have to be directly over it to mark it. I works just like structurescan/sidescan. I have done this several times with as much accuracy as if I had been directly over it.



Now last night you said...

nwright - 8/5/2010 10:53 PM


As for where an object is in relation to the boat using 2D sonar, I could care less. I can move my cursor over that object to create a waypoint. I can then go back to that object without any problem.


The topic of discussion is 2D Sonar and GPS Accuracy.

Triton Mike - 8/3/2010 4:51 PM

I use the 200khz beam for 2 reasons.
1. I get the most accurate GPS waypoints. Narrower beam is more accurate than a wider beam
2. It tells me exactly what fish are directly under the boat and near my spoon (if I see the spoon on the 200khz/20 degree beam side of the sonar split screen).


And you stated

nwright - 8/3/2010 7:50 PM

The cone angle has nothing to do with waypoint accuracy. The waypoint is based upon the HDOP (horizontal dilution of precision) not the vertical. Basically the GPS is marking the waypoint on top of the water, not in the water column.


Now if you want to discuss Side Imaging and Down Imaging and how GPS Works with these systems we can go into discussing Humminbird system of marking waypoints in SI or DI Views. It look like that is maybe what you are asking for???

nwright - 8/5/2010 10:53 PM


Using the logic both of you are using then waypoints derived from sidescan objects are way off and you have a hard time locating them. I never have had a problem marking an object 30, 40, 50ft, etc from the boat and being able to navigate the boat back on top of it.



We are discussing 2 different systems 2D - GPS Marking and SI/DI - GPS Marking. Each has different features and how the technology works.

If you can let me know which system you would like to discuss we can concentrate on that one then we can get into the other one if you would like.

Posted by SpurHunter
8/6/2010 10:31 AM
This essentialy has shown me I have no idea how to use a good depthfinder.
I am lost with all huge amount of info that has been posted here, you guys have been great! I will mark this thread and read it a few times, maybe I can figure some of it out.
Posted by Doug V
8/6/2010 12:01 PM
This brings up a good subject for more video clips to help others understand how the GPS and Sonar Systems work in unison. Got it on my list of Videos to do. Since GPS Marking capabilities are different for different sonar systems it will help that the user understands how and what he is marking and more importantly getting back to catch the fish you found.

I've got several help videos that show features of the Humminbird Product on my YouTube Channel over 30 different Videos and growing because of Ideas I get from questions asked on forums and seminars I conduct.
Here's My YouTube Channel: http://www.youtube.com/user/imonbass

Posted by SpurHunter
8/6/2010 12:13 PM
THat is a great idea. I need to look and see if I can ifnd a model like mine on the tube. I have a Garmin 178C. Cant bring myself to get a Side Scan that is worth more $$ than my boat is!
Posted by Triton Mike
8/6/2010 12:31 PM
SpurHunter - 8/6/2010 12:13 PM

Cant bring myself to get a Side Scan that is worth more $$ than my boat is!


IF it makes ya feel any better Spurhunter I had a 997SI on a electric only jon boat LOL

Posted by SpurHunter
8/6/2010 12:42 PM
But at least your boat doesnt look like its about to fall apart!
Posted by nwright
8/6/2010 10:27 PM
Doug, I haven't contradicted myself at all. I initially questioned Mike's 83/200 split image becaused both images showed the same bottom coverage. The 83khz also showed better definition which is the opposite of what they should show .Mike said " . I get the most accurate GPS waypoints. Narrower beam is more accurate than a wider beam ". I questioned this statement because I can mark an object using either transducer with the same accuracy and that the cone angle had nothing to do with GPS accuracy.

As for comparing Humminbird with any other unit---I could care less. All of them can do the job intended and how well they perform is directional proportional to the skill of the person using them.
Posted by Triton Mike
8/6/2010 10:48 PM
nwright, Not to be argumentative but since your a fan of our buddy Fishton (Lowrance guy) even he agrees on the 200 khz beam being more accurate via GPS. He supposingly runs a sonar school, if that gives him any credibility. Here is an excerpt from one of his posts that he made
.




Edited by Triton Mike 8/6/2010 10:48 PM
Posted by SS810
8/7/2010 1:35 AM
Posted by nwright
8/9/2010 10:07 PM
I'm not a fan of Fishton, I certainly remember the epic battle between you, Doug and him. This would be the first time you have agreed with him on anything. I disagree with him also. Like I said, if the waypoints created using the 83khz, 60 degree transducer are inaccurate then the ones made using sidescan from 60ft away would be usless. In each case I don't create a waypoint without moving the cursor over the object, because you have already passed the object when it appears on the screen. I have created waypoints from 83khz, 200khz and sidescan (455 & 800khz) 60ft away and am able to go directly over those objects time and time again without any problems. If the waypoints created with the 83kz are not accurate, please enlighten me as to how they compare to waypoints created with sidescan, as far as accuracy is concerned.
Posted by Doug V
8/10/2010 1:01 AM
It's about coverage area. 2D Traditional Sonar is cone shaped with each ping. 20 Degree sonar covers approximately 1/3 of depth so in 9 foot of water you have 3' of coverage. in 30' of water you have 10' of coverage get in deep water like 90 foot of water it's a 30' circle of coverage. Now with Dual Beam plus sonar this area of coverage increase to the same as depth. Some with the 60 degree beam in 9' of water you get 6' additional coverage outside the 20 degree beam for 9' of coverage. In 30' of water you have an additional 20' of coverage for 30' of coverage and in 90' of water you have an additional 60' of coverage or 90' of coverage. For Example if something shows up when scanning 30' of water in the 60 degree beam but not in the 20 degree cone it is from 11' to 15' to the side, forward, or behind the transducer. Since the beam is circular in pattern and grows as it gets deeper sonar cannot tell which direction it is in so there is no way to pinpoint the location. With the same accuracy as 20 degree cone with narrower area of coverage. This video shows the Area of Coverage and Dual Beam Coverage. http://www.youtube.com/watch?v=7TdKQyKkShk

Here's another video to help understand a sonar ping: http://www.youtube.com/watch?v=kELam6BWQcc

Since Side Imaging is a razor then beam the unit can calculate distance to the Sides because of the thin thickness (front to rear) the exact location can be pinpointed with Side Imaging and utilizing the Humminbird feature of moving the cursor over the point of interest and marking the location. Side Imaging is a totally different type of coverage area as can be seen in this clip: http://www.youtube.com/watch?v=XP0YwweZVOs features which Humminbird has patented technology on. You can search the Internet on these patents to learn more.

Posted by Triton Mike
8/10/2010 7:07 AM
I hope nobody reading this thinks we are crazy LOL. I'm only continuing this discussion because I feel like people are learning from our dialogue. If it helps someone than it's worth it.

Norman, To further what Doug stated. Sonar is a CONE it has a circle for a footprint. It has no perception of left or right, frontwards or backwards. For instance. I have TWO brushpiles in this image below. How do I know this? I put them there and they are approx 15ft apart.. I want you to put your cursor on the LEFT one? Now do you understand? You can't put your cursor on the left brushpile because the sonar doesn't know left from right it lumps them both together on the screen because they are both in view of the sonar cone. Down Imaging works similiar.

Side Imaging knows left and right and that is why you can use the cursor effectively. Keep in mind I said MOST accurate GPS coordinates with 200khz. I didn't say you can't mark a brushpile in any other beam cone to mark brush because you can. If you happened to run over it with the 200khz cone in dual beam then yeah it will be accurate. If you run over a 30ft tree and mark a waypoint then yeah you have a good shot at being able to snag the tree with your spoon. But will you be fishing the trunk or the top of the tree? But if the structure is off to the side of the 200kzh beam then it will be off some.

Here is the sonar shot with TWO brushpiles in the sonar image. Which one is the left one and which is the right one? Or is one in front of the other?? You have no way of knowing with sonar..



To further illustrate my point. You made the comment that the GPS marks the TOP of the water.

nwright - 8/3/2010 12:26 PM
Basically the GPS is marking the waypoint on top of the water, not in the water column.


You are correct and based on that fact look at these diagrams. The RED X under the boat marks the GPS points. Both of these trees are within the cone beam and show up on your sonar. Which GPS point is more accurate? The one directly under the boat in the 200khz or the one off to the side??



Edited by Triton Mike 8/10/2010 7:50 AM
Posted by BADKARMA
8/11/2010 10:30 PM
Glad to see you on this site, Doug. This may save me from having to run over to other sites to ask you and T-Mike annoying questions. LOL. Really, guys, thanks for all the help you have provided so far about these units. Your help in invaluable. The resent tips about mounting locations for the SI ducer have empowered me to try and mount it myself with some confidence that it is in the right place. Welcome.
Posted by nwright
8/12/2010 11:13 PM
Now do you understand?

Wow, I just thought I new how to use my equipment. Now I don’t have any “eye candy” to include with my replies so I’ll just have to stumble along without any.

I have a layman’s understanding of sonar and GPS technologies but I have managed to get by. Pinpoint accuracy is very seldom needed in a fishing application, but sometimes that is what I strive for. If it was that critical I would use the position averaging feature which was on some of the older units and is on my handheld units.

Many years ago when SA was turned on I used a differential corrections receiver to get three-meter accuracy. A company from California offered the service in Chattanooga so I bought their receiver and a lifetime subscription. They piggybacked their correction data on top of KZ106 FM radio. When SA was turned off the company went out of business and I was left holding the “bag”. Over the years I have owned 18 GPS and GPS/sonar units. I say all this so you will understand this “ain’t my first rodeo”.

I have never had a problem marking a waypoint from an object that showed up on my depth finder/sonar and going back to it and having it show up on my screen again. I have used 50KHZ, 83KHZ, 192KHZ and 200KHZ transducers.

I have no intentions of getting into a 25+-page debate, which happened between you, Doug and Fishton. It degraded rapidly into an ego feeding frenzy. Fishton was never to be seen again.

When I was gainfully employed I would go into a meeting and present data and statistics about a study I had done and people would question me about its accuracy. I learned if I put all that information in spreadsheets and charts no one would question me. Didn’t matter if it was factually true or not as long as I supported it with “eye candy”.

You all have a good day and I honestly have enjoyed the exchange.
Posted by drdetroit
8/14/2010 7:02 PM
Triton Mike

What are the best settings to get the most out of your unit???
Posted by Doug V
8/14/2010 8:52 PM
For Side Imaging Settings this Video Clip should help:

http://www.youtube.com/watch?v=YV-Rh8wXTY0


Posted by drdetroit
8/14/2010 9:31 PM
WOW! That really helps.

DR Detroit
Posted by drdetroit
8/15/2010 11:47 AM
I have another issue. When I ordered my boat the dealer talked me into a 997 on the console and a 797 on the bow. He told me I would have side imaging on both units. Well I only have side imaging on the 997 unit. Can you have side imaging on both units? If so what do I need to do to make it happen?

Thanks,

Dr Detroit

Edited by drdetroit 8/15/2010 11:49 AM
Posted by elwestb
8/15/2010 2:17 PM
Doug V - 8/14/2010 8:52 PM

For Side Imaging Settings this Video Clip should help:

http://www.youtube.com/watch?v=YV-Rh8wXTY0


Whoa! That was the best one I've seen for dummies! Thanks!
Spread the word

del.icio.us Digg Furl Reddit BB Google Ma.gnolia Netscape Simpy StumbleUpon Technorati Live Yahoo!

Jump to page : 1 2 3 4
Now viewing page 2
Jump to forum :
Search this forum
Printer friendly version
E-mail a link to this thread
 

Advertiser

Advertiser

CFF Calendar
May 2021
SMTWTFS
            1
2 3 4 5 6 7 8
9» 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31          

Upcoming events (next 2 weeks)
May 9 Chattanooga Crappie Club TX #2

Advertiser

Random Photo


Album: my fish


(Delete all cookies set by this site)

Copyright © 1996-2021 All rights reserved.
Duplication in whole or in part of this Web site without express written consent is prohibited.
CFF Privacy Policy

Running MegaBBS ASP Forum Software
© 2002-2021 PD9 Software