Author Topic: Need help distinguising if this is inteference. Nice shot of an old bridge too. (Read 25326 times)

Rotus623 · « **on:** March 16, 2014, 09:44:05 AM »

Hey fellas, got my 7 and 8 series units hooked up via ethernet. Been fiddling with transducer location to try and get the best images. I have three transducers on the boat total. Compact SI on TM, HDSI and 2d on transom. Here are some shots on the 798 on the bow, running TM ducer. Obviously there are a lot of fish down there. Caught gizzard shad in the cast net, and a few stripers, so that is my best guess as to what we are looking at. This was a super windy day, and I was on a wind beaten point. I am wondering if the blurry swirls on the SI water column is plankton or RFI.

Then, we have a whole separate issue. These shots are off the 898, transom ducer. When I am going over 4-5MPH I start to get dots all over in the SI table. Drives me nuts. Unit is wired to its own battery. When I slow down to 2-3MPH the little dots seem to go away. My best guess is bubbles? Should I move the ducer up just a hair? You can see some "fish" in the 2d screen, but I doubt all those dots on 2d are scattered fish.

And this just drives me nuts. When I am underway, I can get a great bottom reading, but have a ton of slop everywhere else on the screen. This looks like this from all on plane readings, with surface clutter set to 0. You guys think I should move the 2d ducer up a smidge?

And lastly, here is what you want to see on the lake when on the Striper hunt!! In the second shot there is a really cool old bridge that I have landed some really nice largemouth and catfish off of.

LOTS OF BAIT!!!!!

castle rock clown · « **Reply #1 on:** March 16, 2014, 09:27:21 PM »

In the images where the waviness appears was the boat rocking side to side? On some of the first images displayed what was your sensitivity set at, it looks to me as it might be a bit high. Later images seemed nice. I'm just learning myself, hope others chime in with more experience.

Rotus623 · « **Reply #2 on:** March 16, 2014, 10:39:12 PM »

Yes, it was a windy day. The first two pictures have a haze in the SI view that I am wondering about. The third picture has little white spots everywhere that puzzle me. I also want to know what I can do to get the mess to go away with the 2d readings while on plane. Just waiting for Rickie, Greg or one of those boys to chime in.

rnvinc · « **Reply #3 on:** March 17, 2014, 10:24:55 AM »

When I see haze like that in my SI images, it's usually 1 of 3 things...

*Propwash...(which I suspect your seeing)...as looking like flowing hair or a long oblonged shaped puffy cloud...
*Algae Bloom...this usually covers the entire water column from a certain layer in the water column out into the rest of the SI image...
*Baitfish pods...usually smaller cloud like returns..

The random white dots in some of the images can be scattered fish echoes or floating leaves and debri...
Or (if the dots are somewhat uniform looking)... and continue to show in another part of the lake...this is usually crosstalk interference from another sonar unit or an electrical device on the boat emitting RF...

As the white dots disappeared in the amber SI image...the dots would most likely be either...::

*Truely fish echoes or floating debri when the blue shots were taken...
*Or the electrical device that was running in the blue shot...has been turned off before taking the amber shot...

The deep clutter in the yukky 2d image just looks like silty water in the lower depths of the water column in that part of the lake...or RF being emitted from the big motor ...and as the clutter went away at slower speeds...I suspect spark plug RF...

Rickie

Rotus623 · « **Reply #4 on:** March 17, 2014, 11:10:08 AM »

Rickie, as always thanks for the reply. I find your opinions on RFI one of the most valuable on the site.

I believe that the first two pictures with the haze in it could be one of two issues. 1.)Plankton or algae, because it was sunny and I was on a wind beaten shore on a windy day. The other issue could be the way that I have wired the TM transducer. (As far as I could tell) Doug V. ran the ducer wire through the spring shaped power wires on his terrova like the picture below, but I may back the wire out and wire tie it TO the wire rather than THROUGH it.

About the white dots, I did catch a significant amount of leaves in the cast net, so that could be a possibility, but when I slow down they almost all disappear. I got them all day when I ran the gas motor over 4MPH. I dont believe that I got them at all with TM, but the TM only pushes me 2-3MPH. The blue screen was when I was running the gas motor. The orange screen is just TM or drifting. They were also on different spots on the lake. I have the units on their own battery sources. My trolling motor and starting battery are tied together with my onboard charger so there is a wire that runs from the bow (where the charger is) to the starting battery in the back of the boat. Maybe I should get some ferrite rings on the transducer cable, or put a switch in the charging wires just in front of the starting battery so I dont have AC running up beside all of my signal wires?

And lastly, I dont think what is coming into the 2d screen is silt because I see clearly to the bottom when not on plane, and then when on plane I get that mess. Heres some pics of the HDSI and 2d ducers. Maybe the 2d is a little low in the water? Bleh, sorry for the novel Rickie.

-Pete

That is silicone on the keel where I tried to smooth out the rivets some. I am going to use 5200 and make a smoother surface back there to prevent as many bubbles. As far as mechanical interference goes, it is better to have the ducer a hair lower than necessary rather than higher correct?

Humminbird_Greg · « **Reply #5 on:** March 17, 2014, 12:41:20 PM »

I was thinking prop wash or the bottoms of waves in the first two images. The same swirl pattern looks to be in the lake bottom sonar returns as well so the swirl affect may be from turning the boat or trolling motor.

The Si with the dots in it look more like some type of interference. You will have to do some step by step testing to figure out the source though. Find a speed and unit settings that it will consistently show up on and turn one device on than off and see if it comes and goes or not. Check your trolling motor at different speeds. Kick your main motor out of gear and, while drifting, run it at different RPM levels.

The on-plane 2D sonar readings looks like you are starting to get air bubbles around the transducer, especially since the Surface Clutter menu is maxed out for not showing surface clutter readings. Try lowering the transducer some if you can. Sometimes it also helps to angle the back end of the transducer downwards some. This would be the 2D DualBeam transducer in your set-up. Main motor interference can also cause this so test as indicated above (rev while out of gear), but the interference is usually more uniform through the whole water column.

Rotus623 · « **Reply #6 on:** March 17, 2014, 03:11:16 PM »

Greg, I think you may be correct on the prop wash for the first two shots. Keep in mind it would be TM prop wash. I took this out on a calm day and did not see any of this strange haze. The rear unit did not have any of this mess on the screen while running off of the rear ducer.

As for the white dots in the SI, this is the first time I have encountered this. I have two things that have changed. One is I now have another unit linked to the console unit and wires going down the TM to the front transducer (although the unit did it even with the ethernet cable unplugged). The other is that I moved the HDSI transducer down some. So it is from one or the other. Ever since I put my console unit on a stand alone battery I have not had ANY interference until this point. Also I am pretty sure the 2d issues are ducer placement related. When I rev the motor in neutral it doesn't make a difference. I will try getting in motion and then knocking the motor out of gear or turning it off next time out. Man this has got me scratching my head. It is so worth the extra effort to get everything figured out and get some clean readings.

Any recommendations on where I can get ferrite rings for TM or transducer cables?

Rickard · « **Reply #7 on:** March 17, 2014, 04:04:26 PM »

Quote

The third picture has little white spots everywhere that puzzle me.

Hi, If the spots are mirrored, which they are in this case, between left and right SI image halves, they must have the same origin, which makes RF, or some other type of electromagnetic interference source, the only possible explanation. I have this problem in a boat with a veteran engine, but have got used to it...
Rickard

Rotus623 · « **Reply #8 on:** March 17, 2014, 04:29:32 PM »

Quote from: Rickard on March 17, 2014, 04:04:26 PM

Hi, If the spots are mirrored, which they are in this case, between left and right SI image halves, they must have the same origin, which makes RF, or some other type of electromagnetic interference source, the only possible explanation. I have this problem in a boat with a veteran engine, but have got used to it...
Rickard

Well Ill be!! They are almost exactly the same on each side. Thanks Rickard I never even noticed that! Youre the man! Now at least I know where the issue is coming from. Stinks though because I have a stand alone battery. I am going to re-route the transducer cables.

rnvinc · « **Reply #9 on:** March 17, 2014, 09:10:17 PM »

You can get ferrite rings at Radio Shack ...

Or call HB and they will probably send you some...

Are you running 2 units at the same time that could be causing crosstalk with the 2d beams overlapping...(or even turning the TM enough for the SI beams to overlap)...??

Rickie

Rotus623 · « **Reply #10 on:** March 17, 2014, 10:02:33 PM »

Rickie I have the units networked and they share transducers. I always set the units both on one transducer or the other. I am going to lower the 2d ducer a tad and also separate my power wires and my transducer signal wires more than they already are. Also add some ferrite rings. (Do you typically add the rings to the signal wires or the power wires? If I add it to the power wires can I clip it around positive and negative together or does it have to be separate? Thanks!!)

rnvinc · « **Reply #11 on:** March 18, 2014, 08:01:16 AM »

It is my understanding that RF usually enters the depth finder system in 1 of 3 ways...

*xducer cable
*power cable
*head unit itself
*(not sure if RF can get into a GPS cable or an Ethernet cable)...

I have mine on the xducer cable like Doug V explains here...(this is the wire path I diagnosed as the RF entry path into my system...my power wires were far enough apart that RF was not getting into my power wire path)...


Tips 'N Tricks 72: Installing RF Transducer Choke

The concept is to "capture" any RF that may have gotten into the wire paths into the head unit...before the RF enters the head unit...

If the RF is suspected to have gotten into the power cable...the ferrite core would need be installed on the power cable to "capture" the RF before it gets into the head unit..

The ferrite core should be installed as close to the head unit as possible...to eliminate any "extra" wire path between the ferrite core and the head unit for another avenue for RF to get into the head unit...

Rickie

Rotus623 · « **Reply #12 on:** March 18, 2014, 09:37:42 AM »

Thanks Rickie. The stock power cable with the bird already has a ferrite ring on it so I will start with one on the transducer cables. If that doesn't handle it I will try the GPS puck and Ethernet cable, although when I disconnected the Ethernet it did not clear up the RFI. Cool thing is the Shack has them for $2.99 each so I will get more than I think I need.

Humminbird_Greg · « **Reply #13 on:** March 18, 2014, 10:42:59 AM »

Quote from: Rickard on March 17, 2014, 04:04:26 PM

Hi, If the spots are mirrored, which they are in this case, between left and right SI image halves, they must have the same origin, which makes RF, or some other type of electromagnetic interference source, the only possible explanation. I have this problem in a boat with a veteran engine, but have got used to it...
Rickard

You are “The Man” Rickard!
I never thought to look for mirrored interference until you stated it.

Humminbird_Greg · « **Reply #14 on:** March 18, 2014, 10:47:21 AM »

Quote from: Rotus623 on March 18, 2014, 09:37:42 AM

Thanks Rickie. The stock power cable with the bird already has a ferrite ring on it so I will start with one on the transducer cables. If that doesn't handle it I will try the GPS puck and Ethernet cable, although when I disconnected the Ethernet it did not clear up the RFI. Cool thing is the Shack has them for $2.99 each so I will get more than I think I need.

Rotus,
Not all ferrites are equal. I would contact Humminbird and use the ones from them to make sure you are trying to attenuate the correct frequencies.

When you unplugged the Ethernet cable; did you unplug it from the unit that was showing the interference (898)? If not, the Ethernet cable would still act as an antennae if it is still connected to the unit.

Rotus623 · « **Reply #15 on:** March 18, 2014, 11:56:34 AM »

Greg I did pull the cable from the 898. And I will certainly call Hbird and see what kind of ferrite they are recommending.

Rotus623 · « **Reply #16 on:** March 18, 2014, 01:16:47 PM »

Greg, thanks again for your direct support. I called Humminbird and dropped your name stating that you advised me to get a ferrite ring from Humminbird to correct my issue. She pulled up my Myhumminbird account, saw two units registered, and sent me out two rings. Talk about service!

She did have one question. She asked me what trolling motor that I had and I told her MK Terrova, but that the interference was coming from an outboard motor. She informed me that the rings were specially designed for TM interference and she wasn't sure what they would do for outboard noise. She also asked me which ring you recommended me to get and I told her I didnt know.

So my final question for you, Greg, is this: will the ferrite rings that are designed for the TM also filter out outboard noise, seeing as it is designed to attenuate the incoming signal for only the frequencies which the H-bird finds useful?

Humminbird_Greg · « **Reply #17 on:** March 19, 2014, 12:40:31 PM »

I was thinking the 470085-1 Ferrite Rings (the only user installable ferrite rings that I know we have) – not the TMC-1 which is special made for the trolling motor power wiring. These will help for main motor noise as well but you need to know which cable to put them on. I have seen interference come in on any and every cable, so you need to determine how it is getting into the unit first before installing any ferrites. I would try testing with the GPS and Ethernet cables disconnected before trying to install a ferrite on the transducer cable.

This is assuming that those dots are coming from the main motor. You stated that you revved the motor but the dots did not appear. Normally if you are having main motor interference the dots would appear at the same RPM level you see them while on the water. Maybe it’s something in the charging system or perhaps it is acoustical noise? What shape is your propeller in, is it bent or dinged up?

Rotus623 · « **Reply #18 on:** March 19, 2014, 12:52:11 PM »

Ok great. They sent me the 470085-1. I unplugged the ethernet cable and did not see a change. I did rev the motor up, but I did not see interference on the 2d screen. Not sure if I specifically checked the SI screen now that I think about it. The white dots only show up when I have the main motor on. In the amber screen shots there are not white dots, and I had the trolling motor on 6-7 fighting the wind at times. All this info as well as rickards info on mirrored spots have helped me to narrow it down to main motor noise. I am going to re-route my GPS and transducer cables(they are bundled with the bus power wires coming from the gas motor) and yank the GPS antenna plug out and try it again. At that point if there is still interference I will install the ring onto the ducer wire. I will also set the EMF filter on the head unit up higher.

Thanks for all your help guys, as always. Just another reason why I went HB! I will chime back in on Friday or Saturday and let you know how my dry run goes (in the driveway). Its going to be awesome to have 2 units working together with no RFI!!

Bob B · « **Reply #19 on:** March 19, 2014, 06:08:28 PM »

Sounds like a plan......let us know how it works out.

Rotus623 · « **Reply #20 on:** March 21, 2014, 02:27:04 PM »

Okay fellas, as promised I am reporting back. Tested for main motor interference, and sure enough I am getting it. Tried ferrite ring and upping the filters on the unit, and that makes it a measely 10% better. I have a stand alone battery for my fish finders, and a stand alone battery for my trolling motor. I tested continuity to the aluminum hull and cranking battery and that is good to go. Now, it will be relatively easy for me to tie my stand alone battery grounds to my buss (NOT THE HULL). Should I do this? Will this give the interference a path to return? Obviously I will provide a fusible link for each if I were to go this route. I am getting TM interference on my bow unit as well. Man this is getting fun.......

Humminbird_Greg · « **Reply #21 on:** March 21, 2014, 03:46:57 PM »

Maybe you should just call the Humminbird Customer Resource folks back and see what they say. They can get the Engineers involved a whole lot easier than I can.

Rotus623 · « **Reply #22 on:** March 22, 2014, 11:08:24 PM »

Thanks Greg. I got the main motor interference to clear up on the console unit so that is great! But I am getting interference on the bow unit from the trolling motor. With the boat in the driveway, and the 798 on, I do not see any interference in the 2d sonar at all. I see interference on the SI from 30' out and on. So if I keep the SI range at 30' I have absolutely no interference at all. I grounded the trolling motor to my buss and that didnt do anything. Set the internal unit filter to high 3 and nothing. Installed the ferrite ring on the ducer cable and that didnt help either. H-bird suggested that I may have to ground the skeg of my trolling motor to my fish finder battery. I really dont want to drill a hole in my TM skeg that is still under warranty. Any other ideas guys? I may order the ferrite ring that goes in the control head of the TM (TMC-1) and try that. Other than that I am at a loss.....

Humminbird_Greg · « **Reply #23 on:** March 24, 2014, 12:13:42 PM »

Rotus,
You need to do all of the interference testing with the boat and trolling motor in the water. For help with trolling motor interference you should call the Humminbird CRC folks.

Rotus623 · « **Reply #24 on:** March 24, 2014, 03:10:23 PM »

Greg, I called HB, they are sending me a PC-11 power cord (because mine didnt come with one) and she also told me that for the Minn Kota motors that I should ground the skeg of the motor to either the TM battery, sonar battery, or both. Im going to try the PC-11 and if that doesnt clear it I guess I will have to tack the ground up to my skeg.

Rotus623 · « **Reply #25 on:** April 08, 2014, 11:41:28 AM »

So, I spent a week on the lake last week, got all of my RFI to clear up! White spots from main motor cleared up mainly from the ferrite ring as well as rerouting my ducer cable and setting my internal unit filter to high 1. Front unit was definitely prop wash from the windy day because I did get some really nice shots on calm days from that unit. Caught lots of fish too, thanks to these awesome units!!

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Author Topic: Need help distinguising if this is inteference. Nice shot of an old bridge too. (Read 25326 times)

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