Other Interest > DIY - Side Scan Sonar and towfish

Hélix 10 mega G2 Towfish

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abraquelebout:
hi
I use only the Hélix G2 ducer, chirp méga etc...
i dont compare Lss2 and Hélix méga at 455, it come...
there's 10 wire on cable, i cut it and soldier on cat7a ethernet câble, pair to pair, and the black one on the ground. All is ok
i compare pics do with reefmaster and XTF with Deepview 3 fv, the XTF seem's better, it give more information
in this pict Deep is in xtf and "Branches" are the same exept the format, it's better in xtf
silure and carpe are fish take in the Di

Rickard:
Felix, have you made any comparisons between the results when CHIRP is on and off? I guess CHIRP is set on in the default factory settings, but according to the manual CHIRP can be turned on and off for all channels. There also seems to be options for manual setting of CHIRP characteristics (CHIRP Frequency Spectrum). It would be interesting to see how much CHIRP really does to the images, especially in SI. How much will range really be extended with CHIRP? Are the images significantly clearer?

Rickard

abraquelebout:
hi Rickard
It's a good idea, in a next scan i try test chirp and no chrip. problem : with hélix méga you can use chirp, no chirp, get value for chirp frequencies etc....lot of thing
for moment i think chirp mode in 1175 -1275 do 4 cm or under resolution target.
a target made in 2 cm câble it's realy seen, at 25m range by side,  there's no problem for towfish.
in fact, i wonder if i don't make scan with mega side in area made at 455 or 800 khz in past.
one thing is sure, you can't make an error with biological target and other with mega si....
Test are on way...lot of test and for moment good result :D

abraquelebout:
hi, some news
100 scan  with hélix 10 g2 and towfish, no problem, nice pics, it's realy a progress,
for some one who want to make towfish with G2 or other hum in méga imaging i join photo of connect pict, i use a cat 7a ethernet câble, i wire all connect like hum do, soldier wire and it's ok !

I test it at 1200 khz no chirp, and 1150/1275 chrirp, 1175 /1300 khz chirp
1150/1275 usine set are better

in pics "site canons" my new old wreek find, i supose a 1750 corsair ship (pics made with the G2 and towfish)

now i wait a new ducer to make a towfish with 70 m câble

i think let down old lowbird with Lss2 and use only Mega G2, but i don't wonder know if a long G2 ducer it's possible....

Rickard:
Thank you, this is exactly the kind of data I asked for! Very interesting! And congratulations to your success!

It's obvious chirp makes a signficant difference with your gear. Noise is washed away completely with chirp. That kind of noise in the no-chirp images is typical with a long cable. The cable picks up all sorts of interference that makes the image "foggy".

I think the transducer is long enought at the mega-frequency setting. If you make it longer there may be issues with the near-field. At lower frequency, 455 and 800 kHz, a longer transducer will help. Why not try connecting the LowBird to the Helix and run it at 455 and 800 kHz with chirp? The wiring needed is there (separate grounds) and chirp will be effective to some extent even if the LSS-2 is not optimal. If that works, you will have noise-free images with high resolution at long range. But don't blame me if the Helix passes away....  ::)

I have one more comment that has to do with the old issue with gaps in recordings. There are a few gaps in the images. If you give me the permission I can mark them in one of your images?

Kind regards, Rickard

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