R/C for Submarines

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R/C for Submarines

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Viewing 18 posts - 1 through 18 (of 18 total)

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2 May 2014 at 22:39 #48644
Len Morris 2
Participant
@lenmorris2
Hi, can anybody advise on the best frequency for Submarine control? Also (and this sounds very silly, excuse the pun which I'm sure you'll appreciate later), has anybody ever heard of a modulated sound system for Submarine control? Sound travels extremely well in water. I just imagine say a tennis ball size TX on a length of wire chucked in the water and a matched RX on the boat.

Len
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2 May 2014 at 22:39 #5304
Len Morris 2
Participant
@lenmorris2
3 May 2014 at 07:59 #48649
Colin Miller
Participant
@colinmiller68338
40MHz is what the frequency of your radio needs to be

or 27mhz but most people use 40mhz

2.4Ghz will just bounce back off the water I am afraid

As for sound control I have never heard of it but that's not to say

it can't be done

colin
3 May 2014 at 09:25 #48650
Len Morris 2
Participant
@lenmorris2
Dear Colin,

Thanks for that. I now know what I'm looking for. As for 'sonar' control, I bet it could be done to advantage over normal R/C but I'm not clever enough and I doubt the manufacturers would be interested for such a small market. One for the back burner.

Regards, Len
3 May 2014 at 11:19 #48651
Malcolm Frary
Participant
@malcolmfrary95515
None of the radio methods work in salt water, one reason why communication with submarines in real life is so difficult.

A search for ultrasound in water gave a link to a wiki article – http://en.wikipedia.org/wiki/Ultrasound – , this suggested that marine species communicate with high (well above human hearing) frequencies, so no reason why such a system should not work in theory. Piezo-electric ultrasonic transducers are available – whether they are capable of handling the transmission power needed (whatever that might be) and/or sensitive enough to hear the result at a distance is another subject altogether.
3 May 2014 at 17:21 #48659
shipwright
Participant
@shipwright
Len,

Interesting idea.

I had a quick search on the internet and found this technical paper :

**LINK**

Having had a quick look at the paper I concluded that ultrasonic underwater communications is unlikely to be of use to control a model submarine :

a. Unless the range is very short (say a few metres) it is not possible to operate at sufficient signalling rate (the paper reported a range of 70 metres error free communication at 200 bits/second with a transmitting transducer voltage of 200 volts peak to peak).

b. Water is not a homogenous medium (density varies with temperature) and this can lead to smearing of the individual transmission pulses (technically known as intersymbol interference) – this will limit the shortest feasible pulse length. Of course this limitation could be overcome by multiplexing the digital bitstream across several transmitting channels simultaneously but that would be very complex and require a lot of signal processing at the receiver.

I don't have the technical specification for a digital 2.4 GHz RC (radio frequency) to compare with ultrasonic digital system but I am willing to guess that the digital radio system is working at several kilobits/second.

Ian

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3 May 2014 at 22:35 #48671
Len Morris 2
Participant
@lenmorris2
Well chaps, what can I say to all that except thanks for having a look! If I half knew what you were talking about I would try and make a more intelligent comment! However, as I don't I'll just ramble on with a few 'off the wall' comments to see if you clever lads can make anything out of them.

Model sub owners like to dive their boats close to shore. Horizontally 10 metres is far enough and vertically half a metre.

I have all the old Model Maker magazines from 1953 on. R/C in those days was unbelievably crude. Single pulse transmitters, rubber band escapements etc. Still, people still flew model aircraft with them.

Take the old logic, apply modern technology, what could you do with a simple 'pinger' system?

Best Regards, Len
4 May 2014 at 13:10 #48672
shipwright
Participant
@shipwright
Len,

One further point – I had a quick look at :

**LINK**

Although there are some restrictions for radio control wrt diving depth that restriction doesn't seem to be a problem for model submariners – and I assume that you don't operate your submarine in salt water. Is there an issue about radio control and model submarines that I have overlooked ?

And following up your point about the simple mechanisms (escapements) that were used in the past, if those escapements only need an "on/off" switched channel (as opposed to full proportional control) then in principle an ultrasonic multichannel switched system could be feasible (…. but given that RC works for model submarines in fresh water I don't think that an ultrasonic system is worth developing).

Ian
4 May 2014 at 23:03 #48681
Malcolm Frary
Participant
@malcolmfrary95515
Conventional (pre 2.4GHz) radio does work more or less OK in fresh water. However, there is a strong possibility that it will soon go the way of Betamax and 127 size film. Submariners will need an alternative, and an ultrasonic system, if the minor technical niggles of it being basically impossible with present day techniques can be overcome, could be useful. Maybe a low speed information transfer system using a modified Baudot code could send enough information to give enough control? Response times do not need to be as fast as when controlling an aircraft.
5 May 2014 at 08:41 #48692
shipwright
Participant
@shipwright
Malcolm,

Do you have specific information that the 40 MHz band will be withdrawn (for use by RC modellers) ? Or are you just speculating ? I also have an interest in 40 MHz (but surface boat, not submarine) as I use a Robbe twin stick RC system with one of my models and it has features that are not available in other systems (eg coder/decoder that gives several switched channels whilst only using one of the 2 msec "slots" in the transmission frame). Furthermore I believe that Robbe is the only twin stick boat RC system. Sorry if this post is a bit "off topic". If this generates a lot of posts I suggest that it is "bumped" on to a new thread.

Ian
5 May 2014 at 10:48 #48696
Malcolm Frary
Participant
@malcolmfrary95515
Pure speculation based on watching how markets move over the years. Ever tried to find an RC outfit with boat instructions as opposed to flight and buggy? Boats are a minority market, submarines a minor subset of that small market, thus unattractive to major players as a source of income, therefore generally neglected in the interests of making money more easily elsewhere.

Hence the 127 film analogy – once it was common enough to be available from almost any shop because most families had a Kodak Brownie, now there are one or two specialist suppliers for people prepared to fork out for nostalgia. With the growing dominance of what is a generally more capable system that costs less, "conventional" radio will feel the squeeze.

Wandering back to ultrasonics, I wonder if an ultrasonic carrier could handle DTMF. This is the tone dialling standard that phones have used for many years, and there is a family of chips that were developed to handle it over the years Encoding and inserting the signal should be no big problem, receiving and decoding it is the detail where the Devil lies.
5 May 2014 at 14:14 #48700
Len Morris 2
Participant
@lenmorris2
Hi Everybody.

The one thing a good submariner knows is when he is out of his depth! However you've all helped me enormously. Colin's put 40 MHZ in my head. Ian's link to the model submariners site is excellent and I'm sure if anybody could do the job it would be Malcome! (I've added DTMF to my vocabulary just to drop in polite conversation when required).

Here's another pebble I'll chuck into the pond. A long time ago I flew model aircraft. To do it well you need a minimum of 4 proportional channels all under the control of the pilot. Subs are different. Engines, rudders, hydroplanes (bow and stern), ballast tanks (bow and stern) etc. To do it well you need about 8 channels and that's a shed load of stuff for one person to control. Better to have 4 two channel systems on the boat and a crew each with a two channel TX. Captain, First officer, Second officer etc. The Captain wouldn't actually need a controller, he just gives the orders! Much more fun sailing a model boat when it needs a team rather than an over stressed lonesome. Could be done with 4 independat 2 channel systems but I imagine a single 8 channel system with 4 joystick controls plugged into a single TX. Has anybody done it? Could it be done?

Best Regards, Len
5 May 2014 at 14:26 #48701
shipwright
Participant
@shipwright
Malcolm,

Continuing the subject of ultrasonic transmission for control of model submarines.

Following up on your excellent suggestion of using DTMF encoding I came across this small firm who make the complete encoders and decoders (thus saving design effort). However it only offers 6 channels (instead of 16).

**LINK**

This still leaves the question of suitable ultrasonic transmitter and receiver. I have found one example of a submersible transducer but it is very expensive. Also a some form of upconverter and downconverter would be required at the transmitter as the transducers are usually tuned devices operating at several tens of kHz (as you know the DTMF tones are in the band 697Hz to 1633Hz)

Ian
5 May 2014 at 18:53 #48709
Malcolm Frary
Participant
@malcolmfrary95515
I did mention that the devil was in the detail. It was a normal telecom industry trick to get many calls down one circuit to modulate several carriers with audio frequency, mix them at the sending end and separate them out at the other. The downside was the size of the gear to do it, OK on a rack inside a building, in a model, no. Of course that was purely electronic, ultrasonics introduces a mechanical element into the middle, whether any receiver would be sensitive enough to respond to the carrier with enough detail to allow the carried information to be used is another awkward detail. Its a long time since I singed insulation for a living, I reckon this is a job for a younger person.
5 May 2014 at 23:18 #48724
Len Morris 2
Participant
@lenmorris2
Dear Ian and Malcome, I'm sure there is some mileage in this lot and you are the chaps to do it!

Best Regards, Len
22 July 2014 at 11:37 #50576
Richard J Huggett
Participant
@richardjhuggett
The man to talk to about sonar pingers and various other underwater things is John Robinson, what he can't do with sub electronics hasn't been invented yet…although he's probably working on it.

His 12' Gato is an electronic masterpiece…real time sonar, live video playback, auto course settings and corrections, auto levelling via the ballast systems, operating torpedoes and deck guns…you name it, it does it.

If you wish to contact John, pm me and I'll send you his email address, but beware…within four words you'll be totally and utterly confused!

Rich
10 February 2016 at 20:50 #63364
Ron Sindric
Participant
@ronsindric97262
A Submersible Question from a Beginning Sailboater in the States. Does anyone in this forum sub-group make use of FPV ( First Person View ) through a submersible's periscope? Sorry for the bad pun Are there any persons experimenting with probes and sensors for depth ( pressure ), direction ( digital compass and GPS ) along with full duplex telemetry for electronics condition, leaks / bilge pumping, and on-board Black-Box-Style data logging ?

Thanks for taking the time to read my silly questions !
12 February 2016 at 00:04 #63379
John.Redearth
Participant
@john-redearth
Hi Len

In relation to how to control subs I have a video you may be interested in. I am starting out with a new sub build and it seems to me the starting point should be 'how should this work from the transmitter / control' perspective. Not much on that around.

Pls note my approach is quite idiosynchratic but may be helpful to you. I certainly do NOT have all the answers or try to say as much.

Edited By John.Redearth on 12/02/2016 00:04:41
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