Reading the bottom with chirp

 I have been looking at all the screen shots here using chirp tranducers and I am not seeing any variation in the image of the bottom. In the shots of furunos with conventional transducers I can clearly see differences the bottom. Am I missing something or am I better off sticking with my old school gear for looking for dive spots.


JohnF's picture

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 Crank, you are spot on,

Wed, 2018-01-17 19:56

 Crank, you are spot on, Chirp is crap at showing the bottom thickness/hardness. It is because it sends a wide range of cone widths each “Chirp” which smears the bottom reading. Same happens to the top bottom reading but all the computing power goes into painting a clean top bottom line, which some manufacturers like Garmin do VERY well. Unfortunately they put no computing power into painting a clean bottom line which is a pain. 

 

My Garmin Chirp gives a bit better top bottom line than traditional Furuno, much better identification of fish close to the bottom but Much Much worse bottom bottom line.....

 

i wish i had my old Furuno to compliment the Chirp, but I would not give up my Chirp for just traditional. 

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JohnF's picture

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 And no, running in fixed

Wed, 2018-01-17 19:57

 And no, running in fixed frequency with a Chirp unit is stilll not as good as a Furuno traditional....better but not as good. 

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z00m's picture

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Chirp

Wed, 2018-01-17 20:21

 Chirp is about separation of targets above the bottom, not bottom discrimination. This is why it is often packaged with side or down imaging to give you some idea of what the bottom is.

upg's picture

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 Who cares what the bottom

Wed, 2018-01-17 21:34

 Who cares what the bottom looks like if you'e marking fish. That is essentially what chirp is all about. Correct me if I'm wrong

Flaminghedgehog's picture

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Ringing

Thu, 2018-01-18 04:58

 The problem as I understand it is that CHIRP transducers have a very low Q which results in less "ringing" of the element. The ringing is used by broadband sounders to determine bottom characteristics so while CHIRP is superior in target seperation it is not suited to this task. I believe this is why Furuno has avoided introducing a chirp variant of the 585. With the 588 they instead opted to increase target seperation through improved DSP (rezboost).

From looking at hundreds of images from all types of souders I prefer the Furuno broadband units myself for the type of fishing I do in Geo bay. Find good ground and you will often find good fish.

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A freind of mine runs

Thu, 2018-01-18 09:49

 A tzt14 and a r599 through a dff3 and the chirp on this setup gives better bottom and fish shows than my fcv 295 with a r 299 tranny  but not a cheap setup

I also run a hds 12 with a tm 265 next to my 295 and they both show the same fish but the bottom discrimination is now where near as good as the furuno not even close

Flaminghedgehog's picture

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DFF3

Thu, 2018-01-18 15:17

 The DFF3 is a 3KW non chirp unit. Do you mean the new DFF3D? Or maybe the DFF1-UHD?

Stevo81's picture

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DFF3 is not a chirp sonar but

Thu, 2018-01-18 17:55

DFF3 is not a chirp sonar but is selectable RE frequency so can fire the much much more sensitive, low “Q”chirp R599 transducer on any (i think two?) frequencies. 

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ranmar850's picture

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i've looked at a lot of screenshots on THT

Thu, 2018-01-18 11:47

 And the best of them, running CHIRP, can show good bottom discrimination . I'll see if I can find some and post a link

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 Cheap chirp will never show

Thu, 2018-01-18 12:20

 Cheap chirp will never show good bottom, bottom line get what you pay for Furuno spent the time developing everything as there product line focuses more on the commercial sector. 

JohnF's picture

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 Chirp transducers are not

Thu, 2018-01-18 18:20

 Chirp transducers are not the issue....they are awesome and work great with conventional Furuno head units, it’s the actual chirp head unit and how they “translate” the various frequency and cone angle return signals. Conventional Furuno still the best for bottom discrimination methinks. 

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Flaminghedgehog's picture

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 Thats true in part  but

Fri, 2018-01-19 05:26

 Thats true in part  but Furuno have found that low Q transducers do not give the same "thick" bottom readings as higher Q units on the same head units. But you are right it is a combination of many factors.

Quoted from FurunoUSA forum:

"The "q" rating also can have an impact on the thickness of the bottom tail. It has been our experience that a higher "q" transducer can show a different view of the bottom tail"

www.furunousaforum.com/viewtopic.php

 

ranmar850's picture

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And the bottom tail is where it's at

Fri, 2018-01-19 06:51

 For bottom discrimination. You are looking at a number of variables in interpreting the return--those who already know this , bear with me. Your echo return is made of different colours, we all know that they are variations in strength of return. With your classic colour palette, blue background and your strongest return signal is red. Then orange, yellow, green blue as you go to the weaker returns. Good units will have some shades of this as well, ie, dark green/light green, light blue/lighter blue.  Your returned tails will be at their longest when the echo is getting some refraction around irregularities in the bottom (ledges, caves, crevices) before it bouncess back to the reciever. All the colours will be longer, and, in the case of very rugged bottom, you will likely see some yellow patches  up in the red section of the tail, usually caused by large caves and overhangs, in my experience. 

When you are running across very hard but flat bottom, no cover anywhere, usually pretty dead, you will get a very long echo in the strongest colour, red, but the tails below will be stunted. When you hit better, still flat but more broken bottom all the tails will lengthen out, the effect should be quite pronounced. And if you are running Bottom Lock, some life should be evident. I am basing all this around the classic colour palette, not that bloody awful white background/yellow strongest palette that Lowrance has foisted on us, and which I see Furuno has now adopted. I admit to thinking it was pretty cool when I first saw it, but quickly came to realise it was rubbish. At least they give the option of changing it to something better.

Below are some links to good screenshots in varying depth with a high chirp transducer. Details of what he is using are in the text. Bottom discrimination is more than acceptable, IMO.

 

www.thehulltruth.com/8819897-post23.html

 

www.thehulltruth.com/10186742-post48.html

Flaminghedgehog's picture

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Spot on

Fri, 2018-01-19 08:41

 But your links are not working at least for me

Edit: Actually they are working but I see no images?

ranmar850's picture

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they work OK for me, just tried

Fri, 2018-01-19 09:31

   maybe you could try copy and past into a new browser window?

Flaminghedgehog's picture

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Tried that

Fri, 2018-01-19 10:09

 Seems my ISP is having routing issues. Again

gruntre69's picture

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 I might have to try the

Fri, 2018-01-19 12:59

 I might have to try the Raymarine blue palette. I've been using black background which also had red as strong but I don't often show individual fish with any red in them. Nearly always blue...

Good post Ranmar... Cheers...

gruntre69's picture

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 How about this from the same

Fri, 2018-01-19 13:35

 How about this from the same bloke... Pretty impressive! Conditions must have been sweet that day...

www.thehulltruth.com/8821472-post29.html

ranmar850's picture

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yes, I saw that.

Fri, 2018-01-19 14:05

 I wonder what schools up at 1100 metres? something that is all eyes and teeth?  Someone else posted up a reading, on another thread, from 3,300m. It actually seemed to be marking some fish as well as bottom.