Author Topic: testing lowbird side scan sonar on archaeologycal mission  (Read 5834 times)

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Offline abraquelebout

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testing lowbird side scan sonar on archaeologycal mission
« on: September 10, 2012, 09:59:54 AM »
hi
during 3 day i test the "lowbird" sonar
60 m towfish length, Lss2, hdsi 200 khz
it work 8 hours day, no problem, good géoréferencement
whe don't find any interesting thing, lot of beer.
i think the range limit at 80 m .  i test 120 m but there's no more depht
i post a picture in anchoring post near port, 455 khz, whe can see chain, anchoring post at 30m, whe don't find wreek.......
i must say thank to rickard for search of wiring.
Lss2/humminrd give a good job


Offline Rickard

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Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #1 on: September 10, 2012, 10:19:55 AM »
Very nice, now you are the first with a towfish Lowbird system!

And thanks for your recognition! Being able to reach 50 - 60 m at that low altitude (5 m) and with 60 m with cable proves the system is very sensitive with very good range performance! The Birds seem to accomodate the LSS-2 without much pain.
 
Rickard
« Last Edit: September 10, 2012, 10:37:35 AM by Rickard »

Offline PT

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Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #2 on: September 11, 2012, 06:00:05 AM »
Nice work Rickard and Abra.

Pity I built my new towfish using a 898 transducer; however, it still works quite well. It was made using 50 metres of Cat7 cable and has a range of over 40 metres. See attached picture of a small piece of steel wreckage. Unfortunately, there is a bit of interference from my boat mounted 797 which I had running too.

Great work from you two.

Regards

Peter

Offline Rüdiger

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Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #3 on: September 11, 2012, 06:42:02 AM »
A real pioneer achievement by Rickard and Felix !!!
Would be very interesting to see images of the same object with different transducer.

mvh
Rüdiger
Sorry
English is not my first language !
http://de.groups.yahoo.com/group/SOB-International/

Offline abraquelebout

  • volunteer rescue diver, surfer, publicist
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  • Accessories: towfish lowbird /LSS2-hdsi, 60mcable
Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #4 on: September 11, 2012, 07:04:33 AM »
i find interresting thing
two picture, one at 800 khz with HDSI ducer and one in same part of river take in 455 khz /LSS2 ducer
the lss2 give good work,

Offline Rüdiger

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Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #5 on: September 11, 2012, 07:44:37 AM »
Thank you Felix

Still not 100% comparable, because made with different frequencies, but noticeable contrast with lowbird.

mvh
Rüdiger
Sorry
English is not my first language !
http://de.groups.yahoo.com/group/SOB-International/

Offline Rickard

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Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #6 on: September 11, 2012, 10:58:33 AM »
The beam widths in a HDSI transducer at 800 kHz and a LSS-2 at 455 kHz should be the same. The lenght of the LSS-2 should compensate (almost) exactly for the lower frequency. Thus, any differences in image features are due to other factors like better range at low frequency, vertical beam width, design of sound window etc.
Felix, your HDSI transducer seems to have an ambient noise issue in the left channel. Is this a permanent phenomenon?
 
Rickard

Offline abraquelebout

  • volunteer rescue diver, surfer, publicist
  • Full Member
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  • Joined: Apr 2010
  • location: france
  • Posts: 247
  • Unit(s): 898, 1198, helix G2
  • Software: deep,,drdepht,reef.
  • Accessories: towfish lowbird /LSS2-hdsi, 60mcable
Re: testing lowbird side scan sonar on archaeologycal mission
« Reply #7 on: September 12, 2012, 12:44:52 AM »
yes
 i find what is doing noise and gosht in left chanel :
the salt water came into the cable towfish and destruct ground  isolation  5 meter after the connect.
then i change my system, i use marine sikaflex, it's seem's a good solution.
for me 455 LSS2 give aproximative same picture as 800 khz hdsi.
now i'm waiting good condition to go on salt water in wreeck site.
the hdsi is better in vertical beam than Lss2.
in this picture made with lss2 whe can see lines made by panel of fishing boat, (10 cm lines)
during this 3 days whe dive in target (20 cm) usualy find with hdsi at 800 khz.
i'm very enjoy by the "LOWBIRD" system. :)


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