# Your Preferred Sonar Frequency Setting



## GaryI (Mar 18, 2015)

My question is this - Do you primarily use a high (~200 kHz) or medium (~83 kHz) frequency setting for your sonar and downscan?

I have a Lowrance Elite 7 unit. For sonar, my frequency choices are Medium Chirp (centered around 83 kHz) and High Chirp (centered around 200 kHz). For downscan, my frequency choices are Medium (455 kHz) and High (800 kHz). Everything you read suggests using the High settings for both, since you will get the highest detail and best object separation. But my understanding is that the cone angle for the high settings is very narrow. For example, on Livingston for the average depth of 20 ft, use of 200 kHz results in a cone horizontal spread of only 7 ft at the seafloor. The medium sonar setting, which results in less detail, has a cone spread three times wider (21 ft). So for Livingston, I think it makes much more sense to use the Medium settings, even though the detail is less. Otherwise, it is much harder for me to find schools of fish.

Gary


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## Pocketfisherman (May 30, 2005)

Depends on how deep the water is, whether there is a thermocline, and how much bottom detail I want. Higher freq is less range, more detail rendered, and a narrower cone angle for the beam. Low freq goes deep, less affected by thermocline, but less detail rendered and a wider beam cone angle giving a wider field of coverage. Use whichever one you want to optimize the signal for your current conditions.


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## whsalum (Mar 4, 2013)

Once you get the structure your fishing saved on your waypoints I use the higher frequency to narrow down the structure. I have ran to the exact same humps and drop offs for years and the fish don't usually travel to far from them. They don't always bite but they are usually close by.


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## shadslinger (Aug 21, 2005)

I leave my sonar at 200kHz and use the downscan at 455kHz, best of both.


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## GaryI (Mar 18, 2015)

I haven't been happy with the sonar results from my new Lowrance Elite-7 CHIRP unit, so since my first post below I have been experimenting and now I have made some changes which have significantly improved my results. I am posting it here for others who also may be struggling, although sometimes it's hard to know what you are NOT seeing and therefore whether you are getting the most out of your unit.

Prior to this "experimentation", I spent months searching websites, buying and studying DVDs on the subject, and asking guides and experts. Ultimately what led most to my improvement was simply running into a big school of white bass, catching my dinner in 5 minutes, and then spending the rest of the time trying the different unit parameters while I still was over the school. It was unusual that the school hung around for that long. I do not have any screenshots since I didn't plan to do this and I didn't have a chip in the unit. I was in 16 ft of water at the time. I highly recommend that you don something similar, when you don't feel the pressure and excitement to catch every fish.

Up front, I few comments on my situation:
- I mainly fish Lake Livingston in about 25 ft or less of water.
- I am mainly interested in white bass, so my main purpose in using sonar is simply to find and stay over wandering schools of fish.
- My Lowrance Chirp unit has both sonar and downscan capability. I have a transducer which is capable of 83 kHz (medium) or 200 kHz (high) for sonar, and 455 kHz (medium) or 800 kHz (high) for downscan. For the sonar, I can either use the straight frequency or the CHIRP range. Among the unit's (too) many other features, I can also implement noise rejection and surface clarity filters. 
- Up until now, I was running the unit with the following selections:
Sonar - High CHIRP, Downscan - 800 kHz, Noise Rejection - Low, Surface Clarity - Low.

My first comparison was running High vs Medium CHIRP sonar. The Elite-7 unit allows you to run both side by side simultaneously in split screen mode. Much to my surprise, the Medium was much better in terms of identifying fish. The arches were much clear and longer, more arches showed up on the screen, and there was less "noise" on the screen. I knew that the radar cone for the Medium is about 3 times as wide, but I still was surprised as the difference. The High CHIRP was slightly better at separation, especially near the seafloor, but I wasn't terribly interested whether there was 8 or 10 fish in the school. At times I caught fish (while jigging), and sometimes the fish only showed up on the Medium CHIRP screen.

I ran the same side-by-side comparison in non-Chirp mode - 83 kHz vs 200 kHz. I was shocked by what I saw. The 83 kHz was much better - that is not what shocked me, since I had just seen that the Medium CHIRP was better than High CHIRP. What shocked me was that either of these straight frequency screens looked better than their corresponding CHIRP screens. The screens on the straight frequencies were cleaner and easier to read and see fish. I do not understand this. Also, the scrolling of the straight frequencies was much faster and therefore seemed to give better resolution to my eye. That effect is described here in more detail - http://www.fishtec.co.za/chirp1.htm. So from now on, I am running straight 83 kHz sonar.

I also experimented with the downscan frequencies and came to the same conclusion - 455 kHz was better to my eyes than 800 kHz for identifying fish. I haven't compared these 2 side by side on a particular subsurface structure detail - I suspect that switching to 800 kHz may be useful in that case.

I was also very surprised at the impact of the noise rejection and surface clarity filters. After experimenting with the different options, I can't see why any fisherman would ever turn these on. In particular, the name "surface clarity" is very misleading. Turning it on doesn't just impact the surface, as I assumed. It basically lowers the sensitivity throughout the entire water column. White bass which showed up yellow near the seafloor on the surface clarity "off" setting, became a reddish blue on the "low" setting. On "medium" they often did not even show up. Also, I saw many fish in the upper half of the water column which did not show up on the "low" setting. From now on, I will put up with some noise on the screen in order to see fish.

I also tried different color palettes, which is more subjective since each person's eye sensitivity and perception is different. For the sonar, the "White Background" setting worked best for me. For the downscan, I found the "Yellow Green" palette to be the best, in large part because it is one of the few palettes to use multiple colors in the downscan mode. This palette is not even described in the manual.

So in the end, I went from these settings:
Sonar - High CHIRP, Downscan - 800 kHz, Noise Rejection - Low, Surface Clarity - Low.

to these settings:
Sonar - 83 kHz, Downscan - 455 kHz, Noise Rejection - Off, Surface Clarity - Off.

I have tried these new settings on many of my favorite spots and I am amazed at how many more fish I am seeing. In a sense I feel disappointed because I feel that I am not getting my money's worth out of all of the advanced features (CHIRP, high frequencies, filters, etc.) that I paid for. I am also disappointed that Lowrance, like most other sonar manufacturers, gives little thought to writing a clear and complete guide to their unit. But basically I am just thankful that now I feel I can really see the fish that are down there.


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## Ducktracker (Aug 1, 2011)

That just went way over this boy's head Gary so this means you will have to go with me and show me.


Sent from my iPhone using Tapatalk


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## GaryI (Mar 18, 2015)

Ducktracker,

I have been out fishing in your boat - trust me, your sonar is working just fine and I wouldn't touch a thing. If you find any more fish, there won't be any left for the rest of us.

Gary


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## GaryI (Mar 18, 2015)

As a followup, I have been using the sonar settings below now for a while for my Lowrance Elite unit (~$500 retail):

Sonar - 83 kHz, Downscan - 455 kHz, Noise Rejection - Off, Surface Clarity - Off, Fish ID - Off, Palette - White Background.

I am very happy ovrerall with these settings, although I was having difficulty distinguishing between different types of fish. The return signal was just too strong. So I made the following adjustments in the Sonar/Adjust menu to the automatic sonar coloring settings:

Automatic sensitivity - Lowered to -5%
Colorline - Lowered to 50

After this adjustment, white bass show up in yellow, catfish in red and baitfish in blue (colors in the White Background palette range from yellow to red to blue in decreasing strength order, with white indicating no signal). Of course, this is just a generalization and it really depends on how far they are from the transducer. So if a white bass is at the seafloor is 10 ft to the side of the boat instead of under the boat, it will probably show up in blue or red instead of yellow.


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## shadslinger (Aug 21, 2005)

Whatever the color palette is, to see how to identify hard scale fish( stripers/white bass/gar/buffalo to name some) from soft fish( cat fish, threadfin shad, juvenile scale fish) turn the color saturation setting to 90% or more and the color everything turns is the color that hard scale fish will be when you get set in a good % for fishing.
I find most of the new units do a great job on auto setting and need on minor( + or - <5% ) adjustment to get a good picture.
Another way is to pass over something you know is hard, concrete,etc... and see what color it is on the screen.
I find the color adjustment setting and set it at about 53 to 60% and it will on most units display a screen that differentiate between scale and soft fish well.
keep in mind that schools of soft fish densely packed will be hard looking in the middle, but will fade to a soft color on the edges, and if shad will show trailing schools close by of soft color.


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## GaryI (Mar 18, 2015)

Thanks for the tips, SS. 

By the way, what is the origin of the name "Shadslinger"? I don't sense that you're slinging a lot of shad these days. Shouldn't it be "Slabslinger"?


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## shadslinger (Aug 21, 2005)

Lol, I used to fish and guide below the dam and liked to send live shad up to the gates with a long rod.
This would catch Stripers when nothing else would.
I'm not sure who started calling me shadslinger, but it stuck.
The Mighty Red-Fin got its name when my kids asked what we should name it. 
They were happy to not spend the day in a john boat anymore.


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## Yort69 (Jan 31, 2011)

GaryI said:


> I haven't been happy with the sonar results from my new Lowrance Elite-7 CHIRP unit, so since my first post below I have been experimenting and now I have made some changes which have significantly improved my results. I am posting it here for others who also may be struggling, although sometimes it's hard to know what you are NOT seeing and therefore whether you are getting the most out of your unit.
> 
> Prior to this "experimentation", I spent months searching websites, buying and studying DVDs on the subject, and asking guides and experts. Ultimately what led most to my improvement was simply running into a big school of white bass, catching my dinner in 5 minutes, and then spending the rest of the time trying the different unit parameters while I still was over the school. It was unusual that the school hung around for that long. I do not have any screenshots since I didn't plan to do this and I didn't have a chip in the unit. I was in 16 ft of water at the time. I highly recommend that you don something similar, when you don't feel the pressure and excitement to catch every fish.
> 
> ...


This was my experience exactly with the Lowrance Elite as well. You figured it out. Not to say that other models won't have different results..


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