Author Topic: 998 Snapshot question (Read 24687 times)

HookonFishN · « **on:** February 05, 2012, 01:16:15 PM »

Can anyone tell me what causes this?

LBloch · « **Reply #1 on:** February 05, 2012, 03:59:15 PM »

Could it be turbulence from the prop? It seems like I've seen that when I put the motor in gear and start to move. As the boat moves forward it clears up.

Lee

Whistler · « **Reply #2 on:** February 05, 2012, 05:50:36 PM »

I get similar noise from the big motor's alternator (I presume) when the RPMs go above 1000. Do you see this all the time...even at idle? I also see similar noise when my bildge and or livewell pumps run.

Bob B · « **Reply #3 on:** February 05, 2012, 07:26:31 PM »

Do you have another unit on in the boat?

HookonFishN · « **Reply #4 on:** February 05, 2012, 08:27:51 PM »

This was while I was idling at roughly 2-2.4mph. Yes I have another unit (798) with the transducer mounted on the TM. I also have some shots and question posted in the 798 forum on it. I have read about air bubbles causing something similar and was wondering could that be it.

Bob B · « **Reply #5 on:** February 05, 2012, 08:35:14 PM »

In that shot, it looked like the interference was mostly on the 2D. Thought maybe you might have another 2D only unit running.

Humminbird_Greg · « **Reply #6 on:** February 06, 2012, 03:01:56 PM »

I was thinking sonar-to-sonar interference as well Bob B. Make sure your other sonar units are powered off and see if this goes away or not.

Air bubbles under and around the transducer can cause lines to appear on the 2D sonar but they should also be showing on the Si and Di sonar as well.

Are you using only the one HDSi transducer with your 998 unit?

sonar2000 · « **Reply #7 on:** February 06, 2012, 03:55:15 PM »

Hookon, the interference looks more like an rf voltage inducement and not another transducer feedback or bubbles..
You have a good image of the area but with lines. Normally bubbles will prevent the signals from going back and forth and the display will lose definition. Here you have a good display, just some interference lines...This usually shows up most on a 2d display...but si will also or can also have the verticle lines....
Check groundings and other power wires running close to your unit wires.
As others have posted before it is a good idea to run the sonar on its own isolated power supply.
Chuck

HookonFishN · « **Reply #8 on:** February 06, 2012, 10:14:26 PM »

K, thanks guys for your replies on my next trip out I will run one unit powered up and see how does this work out, the trip previous to this one I didn't know how to record and take snapshots and I also only ran one unit and didn't see any of this so I will take a look at that and also I will take a look my grounding or individual power supply. Again thanks to all and I will keep everyone posted after my next outing which it may be a couple of days.

HookonFishN · « **Reply #9 on:** February 06, 2012, 10:16:02 PM »

One other thing guys I don't know if it matters but I have a aluminum boat (bass tracker 175) I don't know if this matters much.

HookonFishN · « **Reply #10 on:** February 22, 2012, 09:56:46 AM »

K, guys again sorry its taken me so long to get new images posted after taking your advice but these are the results from my 998 and these images were taken with both units running at the same time. Take a look at images 39 and 40 it all started out ok but then it appears that I started getting more interference so I had to adjust my noise filter to high 1 to remove it. I need to know what affect this will have I seem to remember reading some where that if you adjust the noise filter to high it could have some sort of affect on your returns. Image 41 is after I made the adjustment to High 1 on the noise filter low or medium wasn't cut'n it. I also ran the power supply directly to my cranking battery with a 3amp inline fuse.

sonar2000 · « **Reply #11 on:** February 22, 2012, 07:20:32 PM »

Something at times is interfering with your left transducer. If this keeps up you might try swapping the transducer. some of these had manufacturing problems..
On the 2d screen it does seem to be an interference and this could possibly be due to a bad transducer also.
You might want to swap if possible (transducer)

Chuck

Colt45 · « **Reply #12 on:** February 23, 2012, 08:01:58 PM »

Divide and conquer! Try setting up a drift, in a current if possible, and turn EVERYTHING in the boat off except the HD unit. If the problem goes away it was some sort of RF interference.

Start by turning one device at a time back on with the main engine last to determine the source of the problem. Be sure all grounds are common and make a good ground to the aluminum boat hull as well. Verify your zincs are in good shape.

If the main engine is the culprit have your dealer check the alternator for a bad RF filer.

If the problem is still present with everything off then the issue would be in the HB or associated transducer.

newkid4si · « **Reply #13 on:** February 24, 2012, 12:31:06 AM »

One thing I would check is the lose of 1.1 volts (12.4 to 11.3 ) in about 2 1/2 hours.
In images #39 & 40, I had this happen when another boat passed close by with their unit running.

Humminbird_Greg · « **Reply #14 on:** February 24, 2012, 02:19:50 PM »

Still looks exactly like sonar interference to me guys – but I would look into what is causing the sonar returns on your left Si beam. Set your Si Range to 20 feet and you will be able to see it easier. Try drifting the boat with everything shut off and if it goes away than it is probably caused by air bubbles coming off the left side of the hull; if it does not go away than it is either caused by something blocking some of the left Si sonar or a possible bad transducer. If you suspect the transducer: connect your 998c Si unit up to your 798c Si unit’s transducer to test for this.

Next time you are out on the water and see this: turn off the 798 unit and see if it goes away or not (you will have to turn the Noise Filter menu off for this test).

Turning the Noise Filter menu up higher and higher can have the negative effect of not showing weaker sonar returns.

HookonFishN · « **Reply #15 on:** February 24, 2012, 09:07:17 PM »

Quote from: Humminbird_Greg on February 24, 2012, 02:19:50 PM

Still looks exactly like sonar interference to me guys – but I would look into what is causing the sonar returns on your left Si beam. Set your Si Range to 20 feet and you will be able to see it easier. Try drifting the boat with everything shut off and if it goes away than it is probably caused by air bubbles coming off the left side of the hull; if it does not go away than it is either caused by something blocking some of the left Si sonar or a possible bad transducer. If you suspect the transducer: connect your 998c Si unit up to your 798c Si unit’s transducer to test for this.

Next time you are out on the water and see this: turn off the 798 unit and see if it goes away or not (you will have to turn the Noise Filter menu off for this test).

Turning the Noise Filter menu up higher and higher can have the negative effect of not showing weaker sonar returns.

Greg I have my two units hooked up by ethernet, can I try 998 with the 798 tranducer that way or does it need to be hooked up directly? I also will try to post a pic of my set up to see if that may have something to do with it. I know I have to trim my outboard up to keep from blocking it but I guess it could still be causing some interference. In the mean while I will be out on the water in the morning and will adjust the side image to 20 feet and also use the 798 thru ethernet to see how it does.

Humminbird_Greg · « **Reply #16 on:** February 25, 2012, 11:30:41 AM »

I did not even think about using the 798 transducer through the Etherent connection HookonFishN. That is a great idea. Test both ways: your 998 using the 798’s transducer and the 798 using the 998’s transducer. Make some screen snapshots and see what happens.

When one unit is showing the sonar from another unit’s transducer through the Ethernet it effectively turns off that unit’s transducer thus eliminating any sonar-to-sonar interference. This would be the same as shutting one of the units off.

HookonFishN · « **Reply #17 on:** February 27, 2012, 04:35:26 PM »

Quote from: Humminbird_Greg on February 25, 2012, 11:30:41 AM

I did not even think about using the 798 transducer through the Etherent connection HookonFishN. That is a great idea. Test both ways: your 998 using the 798’s transducer and the 798 using the 998’s transducer. Make some screen snapshots and see what happens.

When one unit is showing the sonar from another unit’s transducer through the Ethernet it effectively turns off that unit’s transducer thus eliminating any sonar-to-sonar interference. This would be the same as shutting one of the units off.

Ok guys here are the latest shots from my 998. These images were taken while drifting in the wind no outboard running. I'm not posting any shots with the 798 turned off because when its off all my images are good so these are all taken with the 798 running. Just as I said in the 798 forum I hope you all can follow what im saying. Image 47 is my 998 on the 998 transducer drifting and remember all these images are the with the 798 running. 48 is my 998 transitioning from the 998 transducer to the 798 transducer. Image 49 is my 998 using the 798 transducer. Image 50 is my 998 on the 998 transducer. Images 51 & 52 is my 998 transitioning from operating with the noise filter from off to low. Image 53 is the 998 operationg with the noise filter on low. Images 54 & 55 is transitioning from low back to off. I hope you guys can follow what i'm saying, I feel like I im still getting some sort of sonar to sonar from my 798 but don't know how to solve it, keep in mind my 798 is operating just fine.

Humminbird_Greg · « **Reply #18 on:** February 28, 2012, 05:41:14 PM »

From the testing you have done I think that you have proven that you are only seeing this interference when two units that use the same 200kHz sonar, are both running at the same time. When you switched the 998 unit to use the 798’s transducer; there was only one transducer being fired and therefore only one sonar unit operating the transmitter and receiver. You stated: “I'm not posting any shots with the 798 turned off because when its off all my images are good so these are all taken with the 798 running.” Which further proves this.

Possible solution (I say possible because it may not always work): set the Noise Filter menu to a higher setting in the 998 unit. This works most of the time and is what I recommend trying first.

For sure fixes: Turn one unit off. Set the sonar to one unit to off. Set one of the units to share the transducer from the other unit.

sonar2000 · « **Reply #19 on:** February 28, 2012, 06:05:51 PM »

I thought that somewhere it was posted that only one sonar unit fires a shared transducer at a time.
Or now are you saying that one fires and both listen..

These should work better than that if you are linking them together..

Again it appears a software issue. Starting to wonder about this....

Chuck

HookonFishN · « **Reply #20 on:** February 29, 2012, 02:35:35 AM »

Quote from: Humminbird_Greg on February 28, 2012, 05:41:14 PM

From the testing you have done I think that you have proven that you are only seeing this interference when two units that use the same 200kHz sonar, are both running at the same time. When you switched the 998 unit to use the 798’s transducer; there was only one transducer being fired and therefore only one sonar unit operating the transmitter and receiver. You stated: “I'm not posting any shots with the 798 turned off because when its off all my images are good so these are all taken with the 798 running.” Which further proves this.

Possible solution (I say possible because it may not always work): set the Noise Filter menu to a higher setting in the 998 unit. This works most of the time and is what I recommend trying first.

For sure fixes: Turn one unit off. Set the sonar to one unit to off. Set one of the units to share the transducer from the other unit.

Yes thats correct all my images are fine when the 798 is off. I was also thinking that I may just have to run the 998 with the noise filter on low and pray that I don't miss out on any returns. I'm to the point where i'm ready to start learning how to know what i'm looking at in my images. I also thought I may just use the 998 when i'm idling looking for fish or structure and then use the 798 when i actuall start fishing. Again guys thanks for replies and suggestion I guess now I will post some images to see if any one can help me understand what i'm seeing. Thanks to all who replied.

Humminbird_Greg · « **Reply #21 on:** February 29, 2012, 08:27:47 AM »

Quote from: sonar2000 on February 28, 2012, 06:05:51 PM

Again it appears a software issue. Starting to wonder about this....

Chuck

Is it a software issue because we cannot overcome the laws of physics?
Whenever you have two transmitter/receivers using the same frequency at the same time you have the possibility of interference. This is true for sonar, radar, radios, etc. Unless you use some sort of coding within the signal there will be interference. We use filtering to help not display the interference at the cost of possibly losing the ability to display the weaker sonar returns – are we wrong for that too?

sonar2000 · « **Reply #22 on:** February 29, 2012, 11:31:53 AM »

Greg, I thought you had said that units connected together only ping one transducer at a time..If this is true then you should not get any interference.
Now if you are running separate units then I can see a possible interference.

Filtering is fine and there needs to be a difference in operation if singularly connected or interconnected...
Singularly it would be the users responsibility to prevent cross pings.
Interconnect/shared ... the units processors should not allow that to happen..

These are only computer after all..

Chuck

Humminbird_Greg · « **Reply #23 on:** March 01, 2012, 09:53:06 AM »

If you have two units that are connected by an Ethernet cable you have the choice as to which transducer data each unit will display. If the units are displaying the sonar data from the transducers that are physically connected to them, than you have two transducers operating on the same boat at the same time and on the same frequency (in this case). Setting the 798 unit to use the 998’s transducer (or vice versa) effectively turns off the transducer that is connected to the 798 unit: so you only have one transducer firing on the boat at that time and so get no sonar interference.

Just thinking out loud here: I guess that we could have the units communicate and have one go through a transmit/receive cycle and than have the other one doe the same and back and forth. This would allow each unit to operate without interference. The downside would be that the update of the chart would be less than half of what it is now (transmit/receive cycle times would be half plus some additional time delay for the sonar of one unit to totally dissipate before the second unit transmits). I don’t think that anyone would want that.

sonar2000 · « **Reply #24 on:** March 01, 2012, 01:04:54 PM »

Just a matter of upping your processor speed..
We should not build problems in the units..
chuck

HookonFishN · « **Reply #25 on:** March 01, 2012, 02:13:54 PM »

Is it possible that HB 360 may do away with this problem since it covers such a large area?

sonar2000 · « **Reply #26 on:** March 01, 2012, 02:22:09 PM »

Good question......HookOn.....
1) Will the unit allow the 360 display to be recorded? Or at least a snapshot?..
2) Is the 360 designed to be used at speeds or just stationary...?
3) Can the 360 be interlinked?

chuck

Humminbird_Greg · « **Reply #27 on:** March 01, 2012, 04:09:40 PM »

Quote from: sonar2000 on March 01, 2012, 01:04:54 PM

Just a matter of upping your processor speed..
We should not build problems in the units..
chuck

No it isn’t Chuck. The speed of sound through water is not affected by the speed of the mpu in the sonar unit.

sonar2000 · « **Reply #28 on:** March 01, 2012, 04:16:52 PM »

But if you coordinate the pings within the processor you can eliminate the cross ping interference.
I can see sonar interference with separate units but not with interconnected units.
There should be no dual frequency pinging simultaneously..
If it causes interference then eliminate possibility.
Maybe though, the writers are not told what to do and make bum decisions..as in lets do it the easiest way..

Chuck

Humminbird_Greg · « **Reply #29 on:** March 01, 2012, 04:26:13 PM »

Chuck it were that simple we and every other sonar company would have do it by now.

sonar2000 · « **Reply #30 on:** March 01, 2012, 04:28:50 PM »

It is not a matter of simple or complex...

If it is causing a problem and it can be solved by software then the users deserve the code to make the units function smoothly and with displays that are not hampered by the interference.

OK, greg, you and I need to take this offline....

Chuck

rnvinc · « **Reply #31 on:** March 02, 2012, 04:30:30 PM »

Quote from: sonar2000 on March 01, 2012, 04:16:52 PM

But if you coordinate the pings within the processor you can eliminate the cross ping interference. I can see sonar interference with separate units but not with interconnected units.
There should be no dual frequency pinging simultaneously..
If it causes interference then eliminate possibility.

Chuck

Is this not how Lowrance has their SI crystals and dedicated DI crystals of the same frequency in the same xducer...??

Rickie

Bob B · « **Reply #32 on:** March 02, 2012, 07:02:05 PM »

Quote from: rnvinc on March 02, 2012, 04:30:30 PM

Is this not how Lowrance has their SI crystals and dedicated DI crystals of the same frequency in the same xducer...??

Rickie

It is also why their side imaging range and beam angle are limited compared to Humminbird.

sonar2000 · « **Reply #33 on:** March 02, 2012, 07:06:21 PM »

Bob, I dont understand this. Can you explain a little more how or why a beam or distance will be limited..
Once again my feeble brain is not understanding...

Chuck

Bob B · « **Reply #34 on:** March 02, 2012, 11:04:57 PM »

Chuck, I don't understand all the technical details involved in this either, but generally it is because of the amount of filtering necessary to get rid of the interference in the SI that is caused by the DI crystal running at the same frequency.....more filtering = less range.

Lowrance wanted better DI, so they sacrificed the SI range to get it. There are always trade-offs.

Guys who love their Lowrance units with LSS1 who are knowledgable and open minded freely admit that Humminbird SI is better because of the reduced beam width on the structure scan transducer.

sonar2000 · « **Reply #35 on:** March 03, 2012, 09:18:03 AM »

Bob, I am with you in that all this stuff makes your brain hurt.

It does make it a bit harder not knowing how these thing work and to simply put your trust in the printed material..

I had hear that about Lowrance also.

I guess it is what you are looking for as bottom line.

For us its 100 feet either side with a depth no greater than 50 feet...and then narrow in.
Any thing greater than that and we go to the MST 600/1200 fish...
I would supose that the fisher people are looking at things differerently also.
fish for me is the old pole and worm...

chuck

Chuck

HookonFishN · « **Reply #36 on:** May 21, 2012, 10:52:22 PM »

Up until yesterday it had been almost two months since my fishing trip and now I have new shots that I like everyone to look at and tell me whats in these snapshots if anything. Its time for me to get back to learning how to use my units.

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Author Topic: 998 Snapshot question (Read 24687 times)

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