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Eyes and Ears for R/C Subs - Finaly, Active sonar is possible for us!

Place for general submarine conversation

Postby Terry Weber » Tue May 13, 2003 9:08 am

I saw an an for a new type of fish finder! Then I went on the net and saw the web site! Take a look at: http://www.humminbird.com/ When the web site comes up, take a look at the link for the "smartcast". The other thing is these two sites: http://hasas.sourceforge.net/overview.html
and http://cetus.pmel.noaa.gov/cgi-bin/geti ... me=ishmael
They offer a way to use passive sonar to locat sounds in the water. Next is http://www.supercircuits.com They have all kinds of small camras and even a few small mic's!
:D As soon as I can afford too, I'm going to try putting these things inside an R/C Sub!
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Postby fbradasc » Tue May 13, 2003 11:34 am

Do you plan to put a PC104(PLUS) sized PC (Pentium IV), running Linux, into your sub for the HASAS ?
And if you plan to use Ishmael, which kind of fail safe you plan to use to avoid that a Winblow$ crash hurts your sub :) ?

I've found something simpler, it's for a terrian robot but can be easily adapted to a sub:
http://users.libero.it/riccardo.rocca/penelope.htm
http://users.libero.it/riccardo.rocca/sensors.htm
The passive sonar sensor consists of three mics filtered (sintonized) to a given frequency, the output of each mic system is a DC tension which can be easily compared against the others mics output, so can be established from which direction comes the higher (or lower) sound, ie. to follow (or escape from) a target (another sub or surface boat). The frequency can be set to a typical propeller rotations per seconds.
To compare the mics output (or poll them) you can use a very cheap PIC microcontroller which can directly act on the servos.
The microcontroller can even variate the sintonization frequency i.e. via a varicap diode...
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Postby PaulC » Tue May 13, 2003 1:26 pm

Guys,

I see these scale sub sonar posts every so often and have to wonder: what are you trying to hear? When I run my boat I receive some pretty stout decibels from the prop and motor just by standing on the shore. If I get in the water with it the thing sounds like a blender set on "pulverize".

The 1:1 boats operate on the principal of being silent and hearing everything else in the water. I don't see how you're going to pick up anything beyond your motor brushes and cavitation. And even if you do hear something, can you tell the difference between the acoustic signature of a smallmouth bass and the trapped air escaping from a sunken shopping cart?

Please don't get me wrong, I'm not trying to discourage anyone. I know what it's like to get a notion that won't go away until you take it to the end of the line. I'm just curious what the pot of gold at the end of this particular line is supposed to look like.




Edited By PaulC on 1052846922
Warm regards,

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Postby Ben Cook » Tue May 13, 2003 5:23 pm

Terry,

The new HUMMINBIRD product looks very promising. The sensor is self contained. All you would have to do is modify the hull. It even looks like the bow mounted dome on the Sturgeon. The only problem I see is that the sensor only interogates 90 degrees. You will have to mount it right. At least you'll know whats under you.

To the last post. If someone is running an active ping in their boat and you have a passive system. With pratice you could probably get fix from the doppler shift. Besides if it's fun, why not try it?

Model on,
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Postby Tom Spettel » Wed May 14, 2003 12:37 am

Terry. take a look at the Legand series, they were zercom before
hummingbird bought them out. i tryed one out on cabelas lake infront of there store and the graphics were the best i had seen in fishng sonar i put the upper half of my Alpha hull on the bottom and the shape of my hull showed
up perfectly. I amnot going to put this in a sub, what i was going to do
was to make a poormans version of the
glomar explorer! I figure if i have
zercom and an aquaview i could find a lost sub within a shorter time period
then going for a swim and looking for it check it out at www.Cabelas.com
Tom
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Postby Britt Boyette » Wed May 14, 2003 1:29 am

Been there, done that. The typical RC submarine makes a bunch of noise. Paul's correct, you CAN'T hear anything else above all the racket your sub will make. Even if you make it so that your ear only points 90 deg. forward, you will pick up all the transient noises put fourt by the inside of your glass hull. The only time you can hear something is when your grounded on the bottom. That seems to be the only time you won't hear the APC running the servo for your planes. Some ESC also whine when you don't get the throttle turned off 100%. It's just more headache than it's worth. Go with a good video system.
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Postby Britt Boyette » Wed May 14, 2003 1:29 am

Are they still making those video periscopes? Those sure looked trick.



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Postby ThierryC » Wed May 14, 2003 4:36 am

Am I seeing things or the Humminbirg Smartcast transducer with the wrist mounted display is only $89.99 ??
And the additionnal transducer is only $19.99 ?
We could have a bow monted transducer facing forward to avoird obstacles and a transducer facing down to see the depth below the keel and other stuff that are under the sub !!!
Apparently the wrist display can display data from both sensors at the same time, looks like we now have a cheap wireless active sonar to put in our boats !!




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Postby bcliffe » Wed May 14, 2003 10:24 am

Thierry,

I agree the Smartcast product looks fairly cool, however my impression of it is that it will only work (transmit) while on the surface, and survive depths up to 100ft. I may stop by my local Hummbird Dealer to ask a couple of questions though.

Some comments on the passive sonar approach. Your own boat noise can be filtered out by using a 3rd mic and mixing the signal. The real problem is without frequency analysis you can only home in on the loudest sound in the water, which may not get you a whole lot if you don't know what that is. Messed around with this a couple years ago and shelved it based on this drawback.

Cheers
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Postby Mihelich » Wed May 14, 2003 11:47 am

Hey Guys,

It looks like to me that this sensor is set up to work like a bobber and can see down to 100ft in depth. It does not say it will transmit from underwater. Any thoughts?

Tom
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Postby ThierryC » Wed May 14, 2003 12:41 pm

It looks like that smartcast is basically a bobber for your fishing line, completely waterproof, from the specs off the Humminbird website the frequence is a 115khz, which is much better than the 2.0Ghz of a wireless camera, with that frequecy I am pretty sure that the smartcast cast broadcast from underwater, probably around a foot deep, maybe more.
There are 10 kind of people, those who undertand binary and those who don't !
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Postby Terry Weber » Wed May 14, 2003 6:33 pm

Terry Weber wrote:I saw an an for a new type of fish finder! Then I went on the net and saw the web site! Take a look at: http://www.humminbird.com/ When the web site comes up, take a look at the link for the "smartcast". The other thing is these two sites: http://hasas.sourceforge.net/overview.html
and http://cetus.pmel.noaa.gov/cgi-bin/geti ... me=ishmael
They offer a way to use passive sonar to locat sounds in the water. Next is http://www.supercircuits.com They have all kinds of small camras and even a few small mic's!
:D As soon as I can afford too, I'm going to try putting these things inside an R/C Sub!
Terry Weber
of Baltimore, Maryland

Well, how about those periscope camra's that I've heard about? Who was selling them, and how do I get ahold of one?


Terry :D
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Postby dietzer » Wed May 14, 2003 6:47 pm

ThierryC wrote:It looks like that smartcast is basically a bobber for your fishing line, completely waterproof, from the specs off the Humminbird website the frequence is a 115khz, which is much better than the 2.0Ghz of a wireless camera, with that frequecy I am pretty sure that the smartcast cast broadcast from underwater, probably around a foot deep, maybe more.

Thierry,

I think the 115khz is the frequency of the sonar, not the frequency of the wireless transmitter. The web site doesn't list a transmit frequency that I could find.

Carl
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Postby Ben Cook » Wed May 14, 2003 7:47 pm

Here's one for you. How about getting an RF Meter, hooking it up to the receiver from your passive system in the boat and tracking/classifying a contact based on the Hertz line? Now that would be cool. If you got good, you could build a database and know exactly who's boat you are tracking.

Ben Cook
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Postby bcliffe » Fri May 16, 2003 8:52 am

Ben,

"How about getting an RF Meter, hooking it up to the receiver from your passive system in the boat and tracking/classifying a contact based on the Hertz line?"

While I admit this would be cool ... it's far from the KISS principle. Besides you would still need to perform some TMA analysis to determine the location of the contact, and I've lost my slide ruler.

With regards to the humminbird product, found a dealer who sells them and took a peek at the directions. The signal will be lost if the transducer is submerged. Looks to be more of a sub hunting device for surface targets.

Cheers
BC




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