192Khz and 200Khz transducer cause interference?

Fishrdan

3# carp VS 40# striper
Nov 10, 2005
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Dan
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18' Crestliner Superhawk, 14' Tracker "Fish Git' RRR"
Anyone know if 2 fish finders, 192Khz and 200Khz, will cause interference with each other? I'm looking to install a second fish finder in the back of my boat and want to go with a cheap 200Khz unit, primarily used for depth (10-100') and to occasionally show marks.

I don't know if I need to go with a 50Khz unit for frequency separation or if a 200Khz fish finder will play nicely with my old Eagle Ultra III 192Khz fish finder.

The existing 192Khz transducer is thru-hull mounted and I want to mount the new transducer thru-hull also, how far apart do the 2 transducers need to be separated? I think there might be a problem with not having enough distance between the 2 transducers since the old one is in the center of the bilge, only allowing 12-16" between the transducers. If that's not enough distance between the 2 transducers, would 24-30" be sufficient? The connector on the old transducer is kind'a beat up, so replacing/moving the 192Khz transducer to the front of the bilge is an option.

Thanks for the input,
Dan
 

Doug720

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Oct 21, 2004
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I had 2 Furuno units ran off one transducer in boat. Furuno had a "Y" cable available so it was a quick install. Both units were 50/200, one was in the house, and one on the deck. It worked out very well.

Just an idea to check out
 

Smudge

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Mar 11, 2005
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If I read it correctly, Dan is going to install a second transducer and head. With only 8k difference in the pulse he most likely will get bleed over and mutual interference depending on how sensitive his tranducers are. The new system with good software and filters may not pick up the 192k pulse from the old sonar, but that's not to say that the old one will not get washed out. Depends on how good the filters are on either unit....


How far apart do they need to be mounted for no interference? 100yds or so depending on sound propagation conditions.

You are much better off going with a 50khz system as your second system or by doing what Doug did and finding a way to install a second head unit that takes it's signal from the existing transducer...
 

Fishrdan

3# carp VS 40# striper
Nov 10, 2005
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18' Crestliner Superhawk, 14' Tracker "Fish Git' RRR"
Thanks for the responses guys, pretty much what I thought. I need to go with 50Khz to eliminate interference with both the sonars running,,, or run one at at time. BTW, the transducer is mounted shoot thru-hull, not thru-hull, my bad :imdumb:

I have a 70's SeaSwirl (no beauty, but dependable and kills fish) that I troll lakes with. I face port while trolling so I can monitor the rods, yet easily glance forward and at the fish finder. It's a PITA focusing on the small depth numbers on the dash mounted finder, so I want to add a second finder in the back which displays depth in BIG numbers. Looking to add something pretty cheap, $100-200.

Regarding the mounting distance of the transducers, how far apart do 192 and 50Hkz transducers need to be separated to eliminate interference,,, or is this not a problem since they have good frequency separation?
 

Smudge

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Thanks for the responses guys, pretty much what I thought. I need to go with 50Khz to eliminate interference with both the sonars running,,, or run one at at time. BTW, the transducer is mounted shoot thru-hull, not thru-hull, my bad :imdumb:

I have a 70's SeaSwirl (no beauty, but dependable and kills fish) that I troll lakes with. I face port while trolling so I can monitor the rods, yet easily glance forward and at the fish finder. It's a PITA focusing on the small depth numbers on the dash mounted finder, so I want to add a second finder in the back which displays depth in BIG numbers. Looking to add something pretty cheap, $100-200.

Regarding the mounting distance of the transducers, how far apart do 192 and 50Hkz transducers need to be separated to eliminate interference,,, or is this not a problem since they have good frequency separation?
I I'm pretty sure it won't matter. I'm used to working on sonars with a little more juice:D, and one of our systems has it's transducer right in front of the another but they have a pretty wide frequency separation....

Besides, some transducers/sonar head unit combinations can operate in 50KHz and 200KHz modes simultaneously and provide both displays. That part is all in the software...
 

Fishrdan

3# carp VS 40# striper
Nov 10, 2005
338
3
Vegas Baby!
Name
Dan
Boat
18' Crestliner Superhawk, 14' Tracker "Fish Git' RRR"
one of our systems has it's transducer right in front of the another but they have a pretty wide frequency separation....
Thanks Smudge, that's the answer I was looking for since I want to mount the new transducer shoot thru-hull right in back of the existing transducer.

I'm probably going to get a 50/200Khz fish finder that runs at 50, 200 or 50/200. That way I can run the old 192Khz finder along with the new one at 50Khz , just the front 192Khz finder or just the back finder at 50/200Khz.
 

Smudge

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I'm just a deckhand...
Ask Airmar a Question

Airmar will give you the definitive answers as they make them.

But it is my understanding that 2 seperate transducers cannot be run at the same time, regarless of frequencies.
Ummm, ok... Oh wait, did I forget to mention that my other job, besides working on a comercial sportfishing boat, is as a Sonar Technician in the Navy??


Hmmm, my bad, musta left that out....
 

Bank Robber

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Ummm, ok... Oh wait, did I forget to mention that my other job, besides working on a comercial sportfishing boat, is as a Sonar Technician in the Navy??


Hmmm, my bad, musta left that out....
uhh I guess that pretty much sums it up!

Thanks for the info by the way ( not to jack the thread ) I'm adding a second ducer to my boat just as a back up and to have a second source for temp. Its also nice to see full screen for the 200 and 50 khz if you want. I was kinda wondering what kinda problems I might encounter.
 

Smudge

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I'm just a deckhand...
Regardless of what I have to say, follow the instructions and reccomendations on what ever unit you happen to purchase, or if you want to have fool proof operation, have your system installed by a reputable and bonded marine electrician/technician...
 

Fishrdan

3# carp VS 40# striper
Nov 10, 2005
338
3
Vegas Baby!
Name
Dan
Boat
18' Crestliner Superhawk, 14' Tracker "Fish Git' RRR"
I'm down to choosing between Eagle and Humminbird for dual frequency sonars that have the option of running only 1 frequency to the dual beam transducer. I own a couple Eagle sonars which I've had good luck with, but don't know anything about Humminbirds, how does Humminbird compare to Eagle? It's my perception that Eagle's are a poor man's Lowrance,,, and a better than the Humminbirds, is this right?

Looks like I'm up into the $200-300 range, but I'm hoping to get the boat setup so I don't have interference between the 2 sonars and can leave them running at the same time.
 

Surg

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Feb 2, 2004
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If you want to run one at a time then you should be running 200khz as it paints more definition for the kind of fishing you do.

If you want to run both at a time make the second unit a dual freq one that you can switch to 50khz, and you'll be fine.

Placement of the TD has more to do with how clean the flow is across the face of the ducer or hull in the mounting location.
You also don't want it to interfere with the flow of water to the engine pickup.
Out of your three choices I prefer Lowrance.

Best of luck.
 

Fishrdan

3# carp VS 40# striper
Nov 10, 2005
338
3
Vegas Baby!
Name
Dan
Boat
18' Crestliner Superhawk, 14' Tracker "Fish Git' RRR"
Yup, I want 2 sonars running at the same time so I'm looking for a 50Khz selectable sonar. The existing 192Khz sonar is mounted shoot thru-hull and I haven't had problems so the new one is going to be mounted the same way in back of the first transducer in the bilge.

I'm narrowing down what I really need, 5" screen that's easy to read at a glance and at night, 50Khz selectable frequency, all other features that I'll need are common between manufactures. I don't need GPS or maps since I know the bodies of water I fish on, or they are small enough that you can't get lost... LOL

The Lowrance X126DF $(330) is the cheapest in their line-up with these features, but over my price range.

The Eagle SeaFinder 480DF ($240) has the features i want, but probably lacking a many features the Lowrance (that I most likely won't use). It's a possibility.

The Humminbird 717 ($200) lower resolution and for some reason I'm not thrilled by Humminbirds. Probably not...

I found the Funuro LS4100 ($210) thats a good possibility. The only thing that's shying me away from this sonar is it looks to be an older or discontinued model.

Anyone have any experience with the Funuro LS4100???
 

Bullshipper

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I have had much better luck with Hummers than Lowrance, and the lowrance I had was expensive.

If you run 2 seperate transducers and finders, one will get the signal from the other, causing interference.

You can run dual frequency readings from the same ducer units, and that is the way to go.

If I was you I would look for a discontinued Garmin 240 blue, or go to their current 250 model. These have 600 watts of power which is more than what you are looking at with the others, and they are cheap, durable, and easy to use with their auto gain-filter features that adjust with depth. I got one with a dual frequency wide beam ducer from West marine for $160, and I think the 250's are around $250.

These will read with good detail down to 3-1000 feet in salt.
 

Smudge

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If you run 2 seperate transducers and finders, one will get the signal from the other, causing interference.
Umm, ok. Maybe I wasn't clear. The only way you will get interference from one transducer to the other is if the frequency separation is too narrow.

Bullshipper,

Do you understand sonar fundamentals? I'm not trying to be a dick, it's just that this is what I do for a living. I think it's actually safe to say I am a techinical expert in the field of underwater acoustics. I have 14 years of practial experience.

If you have two transducers(xducer), both operating at 200KHz or very close to the same frequency, you will get "mutual interference". That's actually the technical term used in the SONAR field. It's actually the term used in any field involving frequency decoding. Like radar, radio, SATCOM anything of the sort.

It's the same as having two radio stations a mile apart both transmitting at 105.5MHz. They'll constantly walk all over each other. Even if one switches to 105.7MHz at only a mile of separation they'll still interfere. But if one switches to 100.5MHz their transmitters can be on the same tower but their frequency separation will be great enough to avoid "mutual interference". That's the same reason why a 200KHz sonar xducer and a 50KHz sonar xducer can be inches apart and not affect one another...
 

Bullshipper

I've posted enough I should edit this section
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Umm, ok. Maybe I wasn't clear. The only way you will get interference from one transducer to the other is if the frequency separation is too narrow.

Bullshipper,

Do you understand sonar fundamentals? I'm not trying to be a dick, it's just that this is what I do for a living. I think it's actually safe to say I am a techinical expert in the field of underwater acoustics. I have 14 years of practial experience.

If you have two transducers(xducer), both operating at 200KHz or very close to the same frequency, you will get "mutual interference". That's actually the technical term used in the SONAR field. It's actually the term used in any field involving frequency decoding. Like radar, radio, SATCOM anything of the sort.

It's the same as having two radio stations a mile apart both transmitting at 105.5MHz. They'll constantly walk all over each other. Even if one switches to 105.7MHz at only a mile of separation they'll still interfere. But if one switches to 100.5MHz their transmitters can be on the same tower but their frequency separation will be great enough to avoid "mutual interference". That's the same reason why a 200KHz sonar xducer and a 50KHz sonar xducer can be inches apart and not affect one another...
This is contrary to what I have heard smudge.

But if you say that you have had experience with these fishfinders and airmar transducers, then the poster can rest assured that 8 hz is enough of a difference to guarantee he will not be wasting his money.

Right?
 

Smudge

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This is contrary to what I have heard smudge.

But if you say that you have had experience with these fishfinders and airmar transducers, then the poster can rest assured that 8 hz is enough of a difference to guarantee he will not be wasting his money.

Right?
Dude, did you actually read my post? He has to run one at 50hz, and one at 192hz. Holy shit!! It's like talking to a brick wall!! I said in my first post that if he has one at 192 and one at 200 he'll probably get mutual interference. If he tries to use a multi freq unit at 50 AND 200 the 192 will pick it up and the 200 will pick up the 192.

One at 50, and his original unit at 192 and he SHOULD be fine. If one picks up the other then it's because it has terrible filters.

Airmar, Wesmar, Foruno, Humminbird, Si-Tex, what ever, if his second SONAR is multi function and can operate in 50KHz only mode then it will not pick up the 192KHz because the head unit should be filtering out anything that is not the frequency being transmitted. It's the head unit and the software running on it that matters. The tranducers are just a speaker/microphone all in one. Hook it up to the right head unit and you can get it to kick out all kinds of freqs...

This is why a multi fuction unit only has ONE transducer, that ONE transducer alternates sending 50KHz and 200KHz pulses and receives them both back. The software in the head unit running an advanced signal processing Fast Furier Transform algorithim, filters one freq from the other and using an internal clock determins depth and density of the objects being painted. The software goes on to display this in what ever way the manufacturer sees fit and is willing to spend the money on.

200KHz gives you a more detailed picture because the beam width and wave length are 6 times smaller than that of the 50KHz pulse. 200KHz has a shorter range because of attenuation or loss of energy due to heat. 200KHz is also subject to more energy loss due to higher reverberation and scattering incidence.

Clear as mud??:D :D
 

Smudge

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I'm just a deckhand...
Furthermore, I forgot that I added a disclaimer very early on in this thread...

Just to add to that, make sure everything is marinized....:rolleyes:
 

Bullshipper

I've posted enough I should edit this section
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"Anyone know if 2 fish finders, 192Khz and 200Khz, will cause interference with each other? I'm looking to install a second fish finder in the back of my boat and want to go with a cheap 200Khz unit, primarily used for depth (10-100') and to occasionally show marks."

This was his question. I think two inexpensive units operating at these frequencies will probably interfere. That is what is what I said. Sounds like you agree.
 

Smudge

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"Anyone know if 2 fish finders, 192Khz and 200Khz, will cause interference with each other? I'm looking to install a second fish finder in the back of my boat and want to go with a cheap 200Khz unit, primarily used for depth (10-100') and to occasionally show marks."

This was his question. I think two inexpensive units operating at these frequencies will probably interfere. That is what is what I said. Sounds like you agree.
Holy shit!! You mean you actually went back and read my very first reply!?!?
 

Bullshipper

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Smudge,

In this statement, you imply that 5 hz is enough to eliminate interference.

"It's the same as having two radio stations a mile apart both transmitting at 105.5MHz. They'll constantly walk all over each other. Even if one switches to 105.7MHz at only a mile of separation they'll still interfere. But if one switches to 100.5MHz their transmitters can be on the same tower but their frequency separation will be great enough to avoid "mutual interference". That's the same reason why a 200KHz sonar xducer and a 50KHz sonar xducer can be inches apart and not affect one another..."


Nice example, but I felt you were wandering off track in the quest to show your knowledge, so I decided to answer the person who was asking the question, as he was laying down his money.

His parameters were 200 and 197 hz.