side scan sonar interferance in the middle

[geggen]

hi does anybody know what the interferance lines in the middle of my scan pictures can be? i am using an analog 500khz system , with klein towfish. sui box and pc31 daq card isis software


her are some pictures, i cant get the away. Are it some adjustement i can do ore shall it be like this with my analog system? shouldent the middle be completly white with no interferance

http://s157.photobucket.com/home/geggen/index

[SonarKing]

Geggen,

The small hash marks (jagged lines) in the middle of your data are "out-of-range-returns) caused by highly reflective items (pierface, concrete, etc.) which are positioned beyond the range of your sonar settings.

The dark and light banding throughout the record is electrical interference. Try grounding the system to the sea.

Hope that helps.

[geggen]

Ok i understand, thanks. I tought it was something wrong with te sonar since it was many black white stripes in the middle of the scan, i tought i should be completly white in the middle.

The scans in this picture was made on an flat sand bottom, i dont think it was highly reflective items in that area.

[geggen]

it is some bnc plug noise and power supply and ground noise. I need an pure sinus generator i think and i have bought an dynaplate grounding plate for mounting on my boat soo i will see if it gets any better

[geggen]

[geggen]

When i fire opp the system onshore in air and adjust on the max gain , initial gain , and slope the picture looks like this.

Should it be like this? i dont know? is it some adjustments i do wrong?

i have tested the daq card , sonar reciver, bnc cables and things like that. Maybe the problem must be in the fish ore cable?

[geggen]

shall it be like this in air when i am adjusting?

[Glennk]

No, there should not be this kind of "backscatter" on your record when running in air.
Try to adjust all gain settings down to a minimum, and look if the records changes.
I have a clue that somewhere in your system there are some connectors and/or cables that are not 100%.
Have you disconnected all connectors and cleaned all surfaces?

[geggen]

I have been thru the system with electro clean. Only i havent claned is the transducers on the towfish.

Maybe it is the gain settings but i dont think that the stripes in the picture should be there anyway

Maybe it is inside the towfish ore the cable who makes the interferance

i will try to adjust all the gain settings and slope down to a minium and se

[Glennk]

Maybe you can upload a picture that show how the images look now after you fixed the cable?
As I understand, the image got alot better when geggen fixed a fault in the cable. :-)

[geggen]

the interferance lines went away after i fixed the cable, ony interferance i have in the picture now is bnc cable stripes but that is easy to fix

[DELPH]

Hi,

Do you have any digital recording available ?

I suggest that you turn off the sonar gain and use software-based processing unless you have an analog sonar and a long cable.
The major stripes accross the range look like cable or grounding problems (BF component)
The noise in the water-column part may be very low signal but much amplified by the gain.

Philippe
http://delph.ixsea.com