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Scan interference / noise, or the less than perfect scan result, while complex and a long list of reasons, in my view can be summed up in 3 simple controlling factors; 1) The hardware effects 2) The user & software and 3) The mystery effect
1) My alum open boat, 4 stroke motor & electrical system had effects, resoled by moving further away... this is the common blame for noise but is that really true...?
2) It is certainly the case with an LSS-1 you must run the scan in manual side scale mode and ideally set the scan limit one step (5m) over what you see to include the dark and you MUST! run the down scan in manual as well to the same scan limit regardless how much dark or if you use it or not... Otherwise you have spikes appear in your image viewed in sonar viewer and there is further timing issue between the scans causing hick-cups...
3) Given the new fish is an aluminium tube with lead & SS screws, you just add sea water and you have a short circuited battery, So yes electrolysis really does cause signal interference... In take 2 the fish is swimming perfectly, alum is painted, lead is wrapped in duct tape, ss screws are greased... a 50% reduction of noise...
While i am dubious over the use of Stainless steel cable with fish, (My short fish don’t have SS cable) (my new fish does) my gut feeling is that the cable would act as transmitter of boat noise along the fish cable, hence side-scan noise... It appears to be right for all the wrong reasons... No idea why call it the “SS cable hum” due to movement through salt water, But it appears a case in tests that SS cable maybe causing diagonal scan noise and the deeper i go the more side scan noise i get ...is this true?... So in take 3 the SS wirer will be replaced with a spectra rope...(see what happens)
Speckle is an interesting interference; A clear case with the new fish at 1 knot there is zero speckle. increase the speed and sure enough speckle occurs... so is it related to clear water over the fish transducer, any turbulence, or in some way the friction of water on the transducer...? Any ideas
Cheers Stu
1) My alum open boat, 4 stroke motor & electrical system had effects, resoled by moving further away... this is the common blame for noise but is that really true...?
2) It is certainly the case with an LSS-1 you must run the scan in manual side scale mode and ideally set the scan limit one step (5m) over what you see to include the dark and you MUST! run the down scan in manual as well to the same scan limit regardless how much dark or if you use it or not... Otherwise you have spikes appear in your image viewed in sonar viewer and there is further timing issue between the scans causing hick-cups...
3) Given the new fish is an aluminium tube with lead & SS screws, you just add sea water and you have a short circuited battery, So yes electrolysis really does cause signal interference... In take 2 the fish is swimming perfectly, alum is painted, lead is wrapped in duct tape, ss screws are greased... a 50% reduction of noise...
While i am dubious over the use of Stainless steel cable with fish, (My short fish don’t have SS cable) (my new fish does) my gut feeling is that the cable would act as transmitter of boat noise along the fish cable, hence side-scan noise... It appears to be right for all the wrong reasons... No idea why call it the “SS cable hum” due to movement through salt water, But it appears a case in tests that SS cable maybe causing diagonal scan noise and the deeper i go the more side scan noise i get ...is this true?... So in take 3 the SS wirer will be replaced with a spectra rope...(see what happens)
Speckle is an interesting interference; A clear case with the new fish at 1 knot there is zero speckle. increase the speed and sure enough speckle occurs... so is it related to clear water over the fish transducer, any turbulence, or in some way the friction of water on the transducer...? Any ideas
Cheers Stu