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What battery for my VIIc?

R/C Submarine modelers

Postby aquadeep » Sat May 02, 2009 7:53 pm

Yes Ramius-II
that works well and I have done it years ago but what is needed is the audio interface unit to tranlate the digital or analog signals to respective audible voice output.

I had used a telephone 900 mgrz TX in the sub that lisned on an open micke to variouse voice modules that when triggered played back there pree recorded info.
It worket very well but did take up some space.

Now with smaller voice recording modules one can make a sub talk back to you all of its functions and added to the video audio signal might work but the signal loss of the video might also lose the audio.

I would go back to the original just FM or AM radio signal for great reception even at depth.
Micro size TX units are available as Bugs,and I would call it : Bug your Sub Telemetry system and wouldn't cost very much.

Dave :D
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"Don't tell me it can't be done!"

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Postby Ramius-II » Sat May 02, 2009 9:30 pm

Hi Dave :D
Congratulations on having something that works and you have an interesting approach! To modulate (add sound) to a transmitter is typically done with analog audio and in the case of FM you set the frequency responce range that can be transmitted by controlling the limits of the deviation. In AM in is done by varying the amplitude or “power” of the carrier signal. This is why AM has the advantage of being able to squeeze frequencies closer together where in FM the carrier frequencies must be spread apart. As for the “open mike” approach I would wonder why you did not simply take all the talking audio modules outputs and use a summing network (much like an audio mixer without level control) whose output would be a direct feed into the transmitter’s audio input? As for digital signals, a simple, small “D to A” chip (8-pin DIP) would do the conversion nicely. If you need a bunch of D to A’s there are chips with multiple, separate D to A’s built in. Conversely, to send digital through the audio channel has the consideration of roll off and the square corners of a digital “square wave” are very high frequency and probably will need to be squared up at the receiver. I also wish to compliment you on your choice of 900 MHz! Most posts I have read talk about using 2.4 GHz which will not work underwater. For my telemetry system I went with a video inserter that adds visual data to what you see out the video camera on board.

Best, Ed
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Postby aquadeep » Sun May 03, 2009 10:30 am

Thank You Rameus II :D

Getting back to the Dewalt batteries ,I found them to be too expensive to be cost effective at this time ,perhaps latter on they will come down and come in a larger variety of shapes.

For now I would stay with SLBs for large subs and NIMH, Lipos for medium and small subs.

Maybe even somthing new soon will come out that beats them all.

Dave :D
"I like submarine comanders ,they don't have time for bull!!" and
"Don't tell me it can't be done!"

President Roosevelt

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