Dual Frequency Vs. Single Frequency

Discussion in 'General Conversation' started by RiverKing, Feb 13, 2008.

  1. RiverKing

    RiverKing New Member

    Messages:
    2,232
    State:
    Yellow Spr
    Do you guys like the dual freuqency fish finders or the single freuqency fish finders...Whats the perks to having one over the other? Will one help you more than the other? Dont know much about the transducers or cone angles, so just looking for some tips.
     
  2. Wabash River Bear

    Wabash River Bear New Member

    Messages:
    3,019
    State:
    Indiana
    I dont really know Matt. Mine is a dual, 20*/60* Humminbird 565. I am going to have Eric (Deerhunter01) teach me more about it at our Indiana gathering. I think the dual frequency allows it to be more defined or absolute.
     

  3. dankitch

    dankitch New Member

    Messages:
    468
    State:
    Henderson,
    Guys, I have a Lowrance LMS 525C DF finder. It is a dual frequency finder. 50/200 I think is the rating of the frequency. I was told "by Lowrance" after buying it that I do not need a dual frequency because I do not fish in water deep enough. I bought it mainly because it has more power (watts) than the same model single frequency. The lower the frequency uses a norrower beam for deep water. Like 200 feet and deeper. I have put it on 50 before and it shows a smaller section of the bottom. I do not use it. I am not sure of the cone angles for each frequency but the lower the number, the smaller the cone angle.
     
  4. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    Go to the Lowrance website and use the tutorials if you want to learn everything about sonar,including frequencies,cone angles,power etc.Most of us do NOT need dual frequencies because we dont fish water that deep.:smile2:
     
  5. jeremiad

    jeremiad Well-Known Member

    Messages:
    2,207
    State:
    Virginia
    I am surprised that the dual-frequency advantage would be related to depth instead of coverage.

    Coverage is the key advantage of dual-frequency SONAR.

    A typical dual-frequency SONAR might have a 20-degree 200 kHz (as would a single-beam SONAR), and a 60-degree 83 kHz beam.

    Simple fact of SONAR: The higher the frequency, the more narrow the beam and the more resolution in the reflection. This is why side-scan SONARs use very high-frequency beams. However, the higher the frequency, the shorter the travel; whereas very low frequencies can travel the globe, high frequencies die out quickly. This is probably why folks promote the 60-degree beam as being great for deeper depths.

    Again, the advantage of dual-beam SONAR in shallow water is coverage. A 60-degree beam gives you a good idea that there is something around the boat, generally fish in the area. The 20-degree beam gives you more precise information about what that "something" is, as well as a good idea about the bottom and structure directly under the boat.
     
  6. metalman

    metalman Well-Known Member

    Messages:
    3,447
    State:
    IN
    Name:
    Winston
    This subject is akin to a real pet peeve of mine.
    Why don't the sonar people get it into their heads that the majority of us are not interested in the fact that our units have 900 or 1500 or 3,000 foot capability.
    I know that sonars have to cover a lot of variables but some of the bells and whistles and depth capabilities are way over the top for the majority of fishermen.
    Even though I have a Humminbird 997 SI unit that I really like, if someone would just bring out a sonar that gave stunning detail, clarity and separation down to 150 feet without the 50 other functions I never use I would buy it in a heartbeat. And please, I don't want any offers to swap my 997 for a flasher:roll_eyes:...W
     
  7. jeremiad

    jeremiad Well-Known Member

    Messages:
    2,207
    State:
    Virginia
    I mean by "related" is "promoted" as in, why would a salesperson promote a dual-beam SONAR as providing great deep-depth capability in the first place?

    It is true that the higher the power, the greater the depth capability. You may not be fishing deep, but don't forget that a SONAR that reach deep in the water can also penetrate a few feet into the bottom. Reflections from the bottom give you a good idea of what you're fishing over.

    Lower frequency beams also penetrate deeper than the higher-frequency ones. The two beams can resolve the surface from the bottom of muck, for instance.

    Maybe I need to write an article about this?
     
  8. Ed Lacy

    Ed Lacy New Member

    Messages:
    40
    State:
    Modesto, Ca
    Maybe I need to write an article about this?

    Would appreciate it if you would. I always get more from an article written by a user than I do from one written by a tech.