Topic: Hélix 10 mega G2 Towfish

[abraquelebout]

Hi
First towfish with hélix méga.
30 m cat 7a tow cable, all things seem's OK.
test at 1275 khz, no problem
Son2XTF work with hélix méga files

[newkid4si]

Nice crisp images. Thanks for posting.

        mike

[Rickard]

Nice, interesting! Which transducer did you use, the standard that comes with the Helix?

Rickard

[rnvinc]

Looks great abra  ...

Rickie

[Rüdiger]

Hi Felix

Very decent pictures, what do you mean by comparison to the pictures with the LSS2?

mvh
Rüdiger

[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

[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

[abraquelebout]

hi
Yes Rickard you can mark them, it's the right way to go.
I see gaps in recording, i don't know if it's the hélix soft  or the Sd card speed  ?
in navigation the screen froze sometime, it stop and go....it make a hole in reccording.
i think test something : put depht in manual and not auto to test if the range changing in 200 khz affect or not the record
Whe have possibility to go over 1275 khz but it make a short vibration in record, i think range in chirp fréquencies would correct this
i must test it.
for the Lss2 the test is interrresting, i must test it but the ducer helix price is prohibitive do to do that for moment.

[Rüdiger]

Hi Felix

Admirable images in impressive sharpness.
A question about the towfish cable; you seem for the Cat cable no additional strain relief to use, if that is true, what kind of cable is it? Preferably with a link to the manufacturer or dealer.

mvh
Rüdiger

[abraquelebout]

hi
it's a 7a sftp câble
https://www.destockable.fr/cables-et-cordons-ethernet/1729-cable-ethernet-rigide-categorie-7a-s-ftp-4-paires-lszh-a-la-coupe-3660834277909.html

it take all the weight and traction, i use it in an another towfish since 3 years, no problem
1.5 metter rope is put on the beginning, câble go inside and fixed on towfish, and  2 m go free around câble, when you make a traction, the rope  close up the câble and it's ok you can go
i must make foto's and post them soon

[Rickard]

Felix,

I didn't want to highjack your thread with starting a discussion on recording gaps, so I put my answer with your image in the old thread: "Data loss when recording".

Rickard

[Rüdiger]

Thanks Felix for the link.

mvh
Rüdiger

[abraquelebout]

hi , i forget the wiring

[Nitro78]

good work!
for information:
To make a cable tie, and in order to avoid an over-thickness, it is necessary to spread out the wipes of each pair, to isolate them by thermo-retractable sheath. at the end of bundling place a heat shrinkable sleeve after having coated generously with flexible epoxy adhesive, this guarantees a waterproofing of the cable.

[bigkahuna]

Does anyone know what each of the wires in these new transducers are for?  Looks like it's 4 twisted pair plus ground.  Would it be possible to use fewer wires if all you wanted was the mega SI (1200 khz) sonar?  Or is it a "smart" transducer using ethernet to communicate with the control unit?

[abraquelebout]

hi
I think there's one pair of wire for DI, the old ducer work with Hélix, i suppose the left and right side way on connector for scan are the same but not sure.
10 wire....+-for right, +- for left,+- for DI, + for 200/83,+for T°, a ground-....?
on my wiring i do the same as humminbird do except the black on ground

[abraquelebout]

Hi
News about méga G2 towfish
IT WORK WELL
verry nice result

[rnvinc]

Looking great Abra  ... I enjoy your Pix from experimental setups  ...

Rickie

[Rickard]

Looks great! Almost no traces from gaps...  The creature in the circle, do you know what it is?
Rickard

[Rüdiger]

Hi Felix

Mega really delivers mega results.
How many meters towcable do you use?

mvh
Rüdiger

[abraquelebout]

Hi
the créature is a jellyfish.
Now i use 3 lenght of cable : 30 m, 60 m, and the next 100 m
these 3 pics are made with 30 m towfish cable
 at 100m there's lot of noise but it work !
i test it on a survey mission with the ship "andré malraux", minstry of culture in france, there's 2 weeks
I have chance to go on this ship and make survey durring 10 day, hélix 12 méga G2, 100 m towcable
nice mission
in pics, hélix méga near multibeam sounder during survey

[Rüdiger]

Hi Felix

This is a chance, many of us are dreaming of it.
Hopefully, you will post about it.

mvh
Rüdiger

[Rickard]

Please, tell us about your experiences from the adventure with André Malraux! Could you compare your gear with the professional systems?

Rickard

[abraquelebout]

hi
The "andré Malraux" is a nice search ship, during the survey they work with a multibeam sounder,  at 40 meter depht, they do 50 m meter range with it.
Their Klein 3900 was on another country (st pierre et miquelon) for another survey.
Whe go on board with a Hélix 12 G2 and 100 m towfish, external GPS (the external gps sem's better than the internal for hélix G2).
the ship is to big and whe have 30m lengh of câble on desk of the ship.
16 kgs weight of towfish, but with current on water whe can't go under 10 meter, that's why whe chose to make the survey in 455 chirp khz with 60 m by side.
at 100 m lenght the 1275 khz work nice, whe do the experience on a wreek some days before because i modify an old towfish for this experience and whe test it few day before going on ship.
(if it's not work  )
now if i can do a report of this mission, nice for big target and survey.
whe make this to search an 1652 war spanish wreek, no find for moment
an hélix 12 g2 must do good pics of target for small price (if i compare to Klein 3900)
and it must use with apropriate ship not bigger, on reasonable depht (whe lost 30m lenght of cable due to the lenght of ship), with the 11 m of my brother catamaran, no problem at 40 m depht.

[pantelis]

If this setup works please informe

[Rickard]

Interesting! If your gear is good enought for professional archeological surveys HB seems ready for a new market! I assume you are still out on the search mission, is that correct? We are all eager to learn what comes out of it.
Rickard

[abraquelebout]

hi
To make an official archéological search mission in France, whe must have official autorisation.
In september whe make a pré order with search project and sponsoring value desire at DRASSM (culture ministery)
In december, if it's ok, whe make full of paper with project definition and dates (weeks, month), end whe send scientifical repport from anterior mission. (1,6kg of paper last year)
after if whe have accord, the DRASSM give autorisation.
during the dates of project it's ok, after you don't have right to do search.
Now whe wait one year to go and search again.
the HélixG2 is good to make survey, this year in a small surface i found 3 marine gun (canon), 2 anchor and one breaked anchor. the pics of hélix are realy good and expressive to get a good target interpretation

[Rüdiger]

Hi Felix

The bureaucracy is probably similar in many countries.
Again, very good pictures.
Are there also comparable pictures between your mega and a prof. Sonar?

mvh
Rüdiger

[abraquelebout]

pics méga g2, towfish 100 m cable over board

[Rickard]

That's fantastic! 100 m with cable is A LOT. Such strong returns at 1,2 GHz with a towfish hanging 15 m above the seafloor should be impossible. I guess it's the chirp-thing that makes this possible.
Rickard

[abraquelebout]

Yes, at  1200 khz it's good, but 455 not, i suppose the size of the array it's not good.
i must test an other frequencies in  khz around 455 to get a best result, the helix méga can do this.

[sss_floripa]

hi , i forget the wiring

I have a question, the individual shielding of each twisted pair should also be connected to the ground?

I know the final shielding covering the 4 pairs should be connected to the ground.

Thanks

[abraquelebout]

hi
look this on forum there's the solution
http://forums.sideimagingsoft.com/index.php?topic=10052.0