Difference in dual beam and dual frequency sounders

[gros21]

Well this relates to my garmin 400c in my kayak. It comes in a dual beam (83/200) or dual frequency (50/200) now I know the 83 or 50 part will effect the range a tad and angles. But is there a real difference? I have the dual beam version but 2 have dual beam running you would need dual freq.


Any ideas

[bigjimg]

Gidday,It sounds like there is some confusion here.The number you are giving are more your frequency or khz.83/200khz or 50/200khz.Typically your cone angles will vary from unit to unit,on my Navman they are 45 deg at 50khz and 11 deg at 200khz.Dual beam and dual frequency are two ways of saying the same thing.Hope this helps.Jim ps You can also mix the frequencies and run both at once.

[gros21]

I under stand that.
With with the garmin 400c u can get
Dual beam model (85/200)
Or dual freq model (50/200)

Is the only difference the freq?

Only other thing I can think of is 2 beams same freq one left one right but that would only be on quad beam or very directional side scan

[bigjimg]

Righto Gros.Maybe there is more to it?Surely other Garmin owners can shed some more info.Jim

[Spin]

You can use split screen with dual beam running. 80 on one side 200 on the other side or what ever transducer you have.

50/200 kHz (dual frequency) 10 or 45 degrees (dual frequency) reaches depths of 1,500 feet
80/200 kHz (dual beam) 15 or 45 degrees (dual beam) reaches depths of 900 feet

Dual beam and Dual frequency is the same thing. they are just trying to confuse people i think
50 KHZ= a 10 degrees cone angle
200khz= a 45degrees cone angle
80khz= a 15 degrees cone angle

cone angle.jpg

[nautimax]

Dual beam and Dual frequency is the same thing. they are just trying to confuse people i think
50 KHZ= a 10 degrees cone angle
200khz= a 45degrees cone angle
80khz= a 15 degrees cone angle

cone angle.jpg

...I'm confused - are you saying that the cone footprint depends on the frequency? Where does the "Cone angle" adjustments fit in all of this please...On my 450s there is an option to change the cone angle, just not sure how this works as my transducer is also a dual freq dual beam type...?
What I know at this stage is that the 50Hz rate will work better in deeper waters and 200Hz is for depths around 100m. From what I can gather the "Beam Width" or footprint is the same thing as "Cone Angle"...? For better resolution you can adjust or make the beam angle narrower.
My question is; If say I am looking at the seabed below at 100m I should have my sonar to ping at 200Hz and if I want to I can narrow that 200Hz Beam/Cone with the adjustments?

[Spin]

I will post this site for people
don't know if its allowed or not but here goes .
See if you can make any sense out of this info or not?

its off a different web site about sounders apparently.

might help some people if you want to read it all.


http://fishinweb.com/messages/messag...tml?1310688251

[nautimax]

Good info there Spin...had to read it over a couple of times for it to sink in and the writer seems to know a lot from experience.
I then went on and search the web some more and found a Garmin site:

http://iqc.garmin.com/eCustomer/KODSelfService/request.do?session={ca274ca0-0912-11e1-680e-000000000000}&event=2&view()=c%7Bba811110-1924-11dc-70f0-000000000000%7D&objectId=&eksObjectId=&objectType=Case&isJumpEnabled=false&isContentJumpEnabled=false&vendorKey=&versionId=105&objectScore=97&from=results

...for Garmin users - it's a very good knowledge base which I will browse some more to find out about changing the Cone Angle...as far as the "dual" freq & beam I attach below a quote from this knowledge base - paragraph 4 answered one of my queries ;

Frequency: This is the frequency the transducer will output.

Single Frequency: With a single frequency transducer, the frequency setting can only be set to 200 kHz.

Dual Beam: The frequency setting on this model is referred to as a "Beam". With a dual beam transducer and a dual beam compatible device, the Beam choices are "Wide" or "Narrow". If using a dual beam transducer and a non-Dual Beam device, the frequency setting will need to be 200 kHz.

Dual Frequency: With this model of transducer, there are 3 frequency settings available: "200 kHz" (for shallow water), "50 kHz" (for deeper water), or "Dual Frequency" (both 200 kHz & 50 kHz running at the same time).

Gain: This function controls the sensitivity of the transducer. For example, when the vessel is in 15 feet of water, the device may lose the sonar display and depth. This can occur because too strong of a signal is being received by the transducer due to the shallow depth and therefore it is unable to read the returning signal. In this case, the "Gain" would need to be reduced on the device. The opposite is true when in deeper water. If your sonar display is not picking up everything, the "Gain" may need to be increased.

Range: This function controls the depth which will be displayed between the transducer and this setting. If "Range" is set to "auto" (the recommended setting), the depths on the right side of the display will automatically track the bottom. The "Range" can also be set to a specific depth. For example, if searching for structure no deeper than twenty feet, the "Range" would be set to twenty feet. The sonar page will then only show returns of what are between zero and twenty feet.
Ultra Scroll: On devices with this feature, this function controls the rate of the scrolling speed on the display. This can be set from "Pause" to "100%".

Depth Line: This feature allows a specified depth to be referenced by placing a dark line at this depth across the entire display.

Whiteline: This function highlights the strongest signal from the bottom to help identify its hardness or softness. The strongest signal from the bottom will appear as a bright color (on color models). On a monochrome display, the bottom appears as a grayscale pattern. A hard bottom displays a thicker bottom while a softer bottom displays a thinner bottom layer. This function can be used to determine the bottom surface for anchoring purposes or for seeking out a specific species of fish by the bottom type they inhabit.

Hope this may be useful for other Garmin users on the forum...

[nautimax]

Dual Beam: The frequency setting on this model is referred to as a "Beam". With a dual beam transducer and a dual beam compatible device, the Beam choices are "Wide" or "Narrow". If using a dual beam transducer and a non-Dual Beam device, the frequency setting will need to be 200 kHz.

Dual Frequency: With this model of transducer, there are 3 frequency settings available: "200 kHz" (for shallow water), "50 kHz" (for deeper water), or "Dual Frequency" (both 200 kHz & 50 kHz running at the same time).

....From the above, I may be mistaken but Dual Frequency is more the specs for the Transducer...and the Beam is a frequency setting in the actual Sonar unit. Thus, if you have a dual beam Transducer and a Dual Beam compatible device you may have an option of narrow/wide settings - depending on your sonar unit...?

[Dodgemeister]

Nautimax - "Whiteline: This function highlights the strongest signal from the bottom to help identify its hardness or softness. The strongest signal from the bottom will appear as a bright color (on color models). On a monochrome display, the bottom appears as a grayscale pattern. A hard bottom displays a thicker bottom while a softer bottom displays a thinner bottom layer. This function can be used to determine the bottom surface for anchoring purposes or for seeking out a specific species of fish by the bottom type they inhabit."

According to my Humminbird 727 instruction book, hard bottoms are shown as a thin display, and soft bottoms (!) are shown as thick.

[nautimax]

According to my Humminbird 727 instruction book, hard bottoms are shown as a thin display, and soft bottoms (!) are shown as thick.

I agree with the above...might be a misprint in the Garmin article I quoted...