Understanding the DFF-3D better

[Titanium91352]

I have a DFF-3D with a R599 transducer. It would be great if you could give a brief description of beam width and beam angle. I understand the sonar is detecting activity 60 degrees starboard and 60 degrees port for a total of 120 degrees.
If I set the beam angle to 40, does this mean that each one of the beams are side by side covering the 120 degrees?
If I set it to 50, is there overlap?
What would be the advantage of 30 or 50 versus 40?
The same questions for beam width.
Is the beam width the angle fore and aft of the vessel?
Advantages of narrow versus wide ( I would assume if you were targeting deeper subjects you would sue the narrower beam to focus the power but would like to confirm)
My goal is to set the scan to target a cross section in the 200 ft depth range. Then set my CH-250 unit to target the range beyond that. It would be helpful to understand the math of the setting as they apply to the DFF-3D to draw it out.

Thanks

 

[Snips]

Titanium91352,
Hopefully these screen shots will help. I am using a WASSP system because the DFF3D doesn't allow me to vary the beam angles once they are recorded. The first example is 40/40/40, next is 10/10/10 and the last has the port/stbd are 10 degrees wide pointed at 40 degrees. The wider the beams the more recorded history you can display. Also the wider the beams the better they do detecting bottom hardness changes.

Snips

 

[Titanium91352]

Thanks Snips.

So I am almost there with the understanding. A couple of follow up questions.

1. When you set these variables, do they apply to the cross section display as well? Or does the cross section view always display the entire 120 degree spread?

2. I understand the port to starboard beam angle and distribution of that angle (beam width). Is the fore and aft spread constant? If so, what is the angle of that fore and aft spread?

3. Finally, I have a nobeltec system on board and noticed more of an indicator like the wasp display. Do you know if this is correct and Nobeltec will display beam angle and beam width on the display?

Thanks for all the help.

Vince

 

[Snips]

Titanium91352,
1. The cross section is a separate display from the triple beam view.
2. The for/aft is the same no matter display is being used, it's roughly 10+ degrees.
3. Nobletec does display the DFF3D the triple beam width correctly.

Snips

 

[Titanium91352]

Thanks Snips.

Got the information for the Multibeam. Will go ahead and build a model around it.

Since I am combining it with my CH-250. I have a question on that spread.

1. On the CH-250 unit when in searchlight mode. I understand the search is done in 6 degree increments horizontally. When I set the tilt, how much of a beam angle is there vertically. For instance at twenty degrees tilt, how much beam angle is being utilized? What I am unsure of and can't find in the documentation is the vertical coverage at a certain range . If I assume a ten degree beam angle like the Multibeam, then the math says at 200' I am measuring activity from 50' - 85' deep. But if the beam angle is less or greater, that figure would be different. Any indication what the vertical beam angle is on the CH-250?

 

[Snips]

Titanium91352,
This type of useful information is available in my Sonar Tip Book that is under Guides in the CH-250 documents section.

Snips

 

[Titanium91352]

Thanks Snips,

I found the document and read through it. A lot of helpful information. With a CH-250, DFF-3D, and a DFF-1UHD, I have my handsfull with information but I think I am narrowing it down. Since most of my fishing is 200 ft and above, I think I will set the UHD to 350 ft for a deeper water understanding of activity, the 3D to 40/40/40 at a depth of 250 ft to see what is happening right under the boat, and the CH250 searchlight to a 1000 ft range, 45 degree sector, and 5 degree tilt. I can then train the sector underneath the kite bait or forward if we are looking for activity.

Gain, TVG, Clutter 101 from there. Again, thanks for the patience.

Vince

 

[Titanium91352]

Snips,

I had a chance to set up the DFF-3D as well as work with my CH-250 this weekend. One thing I am struggling with is the 3D history. I can have activity under the boat showing up on my vertical scan for both the 3D unit and the ch250 but nothing shows up on the 3D history. In fact I have yet to see any activity on the 3D history so far. If I am in depths of less than 650, I can get the 3D history to display the bottom topography, but not seeing any fish activity on the display even though the vertical scan shows some.

 

[Snips]

Titanium91352,
Those targets look pretty weak, if you are trying to display those you will probably need to increase your Fish Detection Level. It's the first item under the 3D display menu.

Snips

 

[MarMax]

Titanium91352,

The for/aft is the same no matter display is being used, it's roughly 10+ degrees.

Snips

Not to hijack anything here but to clarify, the for/aft is fixed at a total of about 10 degrees each way (20 degrees total) or a total of 10 degrees? And whatever this fixed amount is, it's the same in all the display modes (3D, cross section, triple beam)?

 

[Snips]

Marmax,
For/aft is 10 degrees total. Cross section and 3D are 120 degrees port/starboard. The only view you can vary is the port/starboard is the single/triple beam.

Snips

 

[MarMax]

Thank you Snips. I think there is like 12 elements in the transducer which provide 10 degrees each port/starboard so you have up to 40 degrees down and 40 to the sides. Is this correct?

It's amazing technology and hopefully I'll eventually get a grip on all the fine tuning possibilities.

 

[Snips]

Marmax,
The transducer has eight elements and each has it's own transmitter/receiver. The beam steering technology came from our big Omni directional sonars

Snips