Dual Frequency vs Dual beam transducers

[janz]

Can anyone tell me what the difference is. I have some ideas but all the info on them doesn't really clarify how they work. Guess I am sure about the dual freq but dual beam? Is it that both freq run at the same time to record an echo?

[chowder]

Good question! I'm not sure. I thought that dual beam was used to describe a unit w/ 2 different cone angles vs dual frequency in which the sonar wave transmissions are sent at different wavelengths?

[rail bird]

The way I understand it from my Humminbird directions.

Dual Beam, The unit has two frequencies of operation, In my case a 200khz and 83khz. Either or can be selected. The 200khz is a more narrow cone that gives greater definition of bottom structure and works better at higher speeds.

Dual Frequency, blends the 2 frequencies together at the same time to kind of give you the best of both worlds. The electronics in the unit does the blending. You have to trust the judgment of the fishfinder to treat what your seeing as something real.

[rail bird]

Sorry I got the abve backwards.

Dual Freq, different beams.

Dual Beam, blend of 2 or more different frequencies.

[janz]

That was sort of what I was thinking but still not sure. So if I am running 2 fish finders and one is a dual freq set to 200 and the other is a dual beam 83/200 will it interfer with the dual freq 200? Then again if I ran the 50 on the dual freq and the dual beam I should be alright? I searched for hours on this subject and still cannot find out how the dual beam actually works and those I've spoken to about it don't seem to know either. I posted it here figuring with all the knowledge on this board that someone would be able to come up with the answer.

[Gill-T]

The way I understand it, the two frequencies can be used simultaneously on a split screen because at different frequencies they won't interfere with each other. The lower frequency 50 KHz will show deeper objects better, but with a narrower cone. The 200 Khz has a wider cone and shows stuff up higher.

[janz]

Gil you are correct for the dual freq but I am trying to figure out the difference of the "Dual Beam"

[Jack]

Maybe this link will help !

http://www.raymarine.com/raymarine/Subm ... _guide.pdf

http://www.humminbird.com/leading_innov ... -plus.aspx

looks like it could be the same thing

[Erbyjoe]

Janz This is what I will do for you I am putting this web site down for learning purposes only click on the site then click on Understanding and Interpreting a Depth Finder... there are 6 articles there that are very well written for understanding Fish Finders. Hope this helps

http://www.fishinweb.com/ (courtesty of The Fishin'web site from down south)

Chad, Musky or LM, if this is something I shouldn't do please let me know

[spoonfed-1]

Gill-T you might have the 50/200 cone thing backwards.

I run 50 to show my downrigger weights and 200 won't pick them up. Outside of the cone. 200 gives me better detail at greater depths but narrower cone angle.

Glen

[ray koziatek]

yup to what glen said

[Gill-T]

I don't know, according to the Raymarine site I think I got it correct. Confusing.

[janz]

OK guys made for some great reading but already knew most of what was writen there. Although the Hummingbird info "Features

* Precision, 20Ëš beam is optimized for excellent bottom detail, and reveals fish hidden in bottom clutter

* Wider, 60Ëš beam provides greater coverage for fish and bait fish

* View beams separately, side by side, or blended together for the most complete picture

* Find fish and structure in an area equal to your depth"

Looks as if HB's have an option to choose which beams you use or blended together. Just have to figure out if the FF I am interested in (actually 2) for the transom of my boat so when back there I can keep track of stuff has the same option to choose beams (dual beam) Looking at the Lowrance HDS 5 dual beam and the Garmin 400C dual beam. Now another ? can I choose a different beam for each freq ? Hah knew that would throw a wrench in the gears.

[spoonfed-1]

I don't know, according to the Raymarine site I think I got it correct. Confusing.

Don't take my word for it, go here. Airmar makes most of the transducers used on fishfinders.

http://airmartechnology.com/airmar2005/ ... D=3&NewID=

Select product brochures from the technical information section.

Then select transducer product guide.

Jan, you might find what your looking for there also. If not they probably have a Tech # you could call to answere all your questions.

Glen

[salavee]

As I understand it the 50kz is a longer pulse signal (or sound wave) and shorter frequency (50 pulses per second). This allows for better penetration and depth, but shows less definition, The faster pulse 200kz provides a faster pulse rate and higher frequency thus providing better definition but less penetration. Both can be used simultaneously shooting two different "cone angles" through the transducer e.g 20 Degress and 40 degrees. Think of a Shotgun with a full and an open choke. The sonar unit does the arithmetic. I think "beams" and "cones" are one of the same...but, I could be wrong.

[jimski2]

On my old X16, I could vary the pulse length and normal was about 400 microseconds and it would show fish in Lake Ontario to about 120 feet down. When I changed it to 600 microseconds fish would appear up to 200 feet down.In Lake Erie, looking for perch, when I lowered the pulse setting to 50 microseconds, clouds of "bait appearing" fish would become separate fish to indicate perch. It really was amazing to see all the salmon and trout that were really deep in Lake Ontario.

[Gill-T]

That was a good site Glenn, that explains it better.

[janz]

At this point I think cone and beam mean the same thing. So you either get a dual freq 50/200 or a dual beam 83/200. I think I'm still confused. I don't see how after reading all the transducer stuff that you can actually pick a degree cone to assign to a freq at will. It needs to be built into the transducer and its there fore fixed. The 2 diff freq give 2 diff cone angles but they are built in and can't be swapped or shared with each other, at least thats what I understand after doing all the reading.

[ray koziatek]

yup janz i didnt read the link but started doing homework when i started trollin ,so typicaly the 200 (most common )will give you approx 20 deg cone and due to higher feq travel shorter distance is good for but gives you more (pics) so to speek you get better detail in a smaller zone but if you turn off all filters and auto features and put in "arc" mode you can get up to 65 ish deg cone but you need to tweek unit to get bigger cone and suffer a little on detail, the lower 50 or 83 feq travels further" longer wavelengths " (same theory why elephants can communicate from several miles apart they can put out and hear super low freq.) thats why it is recomended for deep water ....but trollers have found due to wider cone tho they may not give as good of detail (less pics kinda like blowing up a cell phone picture to a 8x10" compared to a 35mm or high quality camera ) that they can see back to there rigger balls and even spoons to see fish come to spread but sometimes lower end units need a trained eye to see this. you can angle your 200 hrz slightly back and get same results but sacrafice high speed ability of unit to read bottom which ant no big deal in ontario as we use it for trollin 99.9% of the time and if you dont angle it too much your depth will be very close to actual... Now if ya wanna have a little winter project to the guys with trim tabs you can do as "Top Gun" outa Osweago does and mount a extra transducer on your tabs so you can angle your transduser from the cockpit to snoop way back there to play around with the fish behind your spread.. hope the plummer translation helps.

[janz]

Thanks Ray I do understand all of that but getting back to my origonal question" what is the difference between dual freq 50/200 and dual beam 83/200 other than the 50 vs 83. Can the cones (beams) be switched between the freq or even mixed as the name dual beam refers. I'm almost thinking this is actually a marketing ploy to make you think your getting something extra by calling it a dual beam.

[rail bird]

Thanks Ray I do understand all of that but getting back to my origonal question" what is the difference between dual freq 50/200 and dual beam 83/200 other than the 50 vs 83. Can the cones (beams) be switched between the freq or even mixed as the name dual beam refers. I'm almost thinking this is actually a marketing ploy to make you think your getting something extra by calling it a dual beam.

My old black and white humminbird matrix 25 does all of the above. 3 different modes that I switch between with the press of a button. When it runs in the dual beam mode the electronics in the Fish finder conditions the signal. You will not get the same effect if you run 2 differnt units. I guess all fish finders are different so you have to see what is specific to the one you are looking at.

[ray koziatek]

after my many hours on hold with EAGLE/LAWRANCE... dual beam is just that 2 beams each dedicated to the given cones from mfg with 2 seperate transponders moulded in one tranducer with the (head)unit having 2 seperate recivers again each dedicated to given freq. and screen displayed or both screens (split) .....im not shure but after eyeing many models ive never seen a 200 freq. with a super wide cone 18 to 22 deg being most common range i remember seeing. and the lower freq are always wider cone ... kinda reverse of what we are used to with a flashlight that we can see,(wide cone see closer narrow beam see further) so i would say no to changing cones between freq,due to them being 2 seperat thingies....most if not all high end units ($4000.00 range) have several transponder ports in the head that connect to "your need " trans ducer ...go to Furno site and look at the big boy toy section... am i still Rambling????

[Matthew]

As was previously mentioned. A single beam is one beam created by a transducer element, a dual beam is two beams created by the same or separate elements. For example a 50/200khz transducer has one element that creates a cone width mode at 50khz and length mode at 200khz. The size of the beam depends on the frequency and size of the element, for example a 200khz transducer that has a 1" ceramic element has a 18 degree cone whereby a 200khz transducer that has a 2" ceramic element has a 9 degree cone. The formula to determine the cone angle is 3600/frequency/element size or 3600/200/2 = 9 degrees.

It should be noted that the size of the ceramic element directly relates to the amount of power that can go through the element before cracking the element. For example a quality 1" ceramic element can handle up to 600 watts rms power before breakage occurs. A side note is the a 1" element @600 RMS would cause so much ringing that the surface clutter would be enormous and therefor large amounts of filtering would be needed, the downside to this is fish targets may also be filtered out. Once you get to 600 RMS a 2" element would be recommended. On this same thought, the larger the element the more sensitivity is available since the ringing of the element quiets at a faster pace and less filtering is required.

To complicate things further a dual frequency transducer is far less sensitive then two single frequency transducers and this is simply due to the fact of the element being less efficient since the element has been charged with two frequencies.

To finally answer your question. Dual frequency when producing two cones from a single ceramic element is less efficient, while Dual beams producing separate cones from two separate elements and is more efficient. Best thing to do is ask your manufacturer the configuration of each element to meet your boating requirements.

[stinger]

Here is some good reading that may help you out.

http://www.furunousa.com/Learning%20Cen ... ide-LR.pdf

[waterlogged]

Glen,

Aside to this thread ...... does the 50 show the rigger balls regardless of depth fisihng??