![]() Outside with a clear path (apart from the submarine wall - about 2mm PVC tubing), I was able to get at least 15m range (maybe more, I did not have enough space to test). I attached a 30cm wire antenna to the transmitter, and it was much better. After soldering a 10 cm wire antenna to the receiver, the range was exactly the same. I used VirtualWire library, and without an antenna I couldn't get more than 1 meter range. I received the 433MHz modules, and they worked terrible Since I lose contact with my transmitter at about 10cm, it seems that the tx/rx pain is able to handle a 40dB attenuation.Īssuming that the 433MHz module I ordered can handle the same attenuation (which I strongly doubt), it should lose contact at about 5 meters underwater (since 40dB attenuation is reached at 5m with 433MHz on figure 3). It seems that with normal incidence, 2.4GHz waves should suffer an attenuation of about 40dB at 10cm (extrapolating a bit Figure 3 that only goes up to 1GHz). My biggest worry is that I'll have to amplifiate the receiver signal, and then treat it using the full power of the Arduino (I have seen tricks with Arduino registers to read inputs fast enough to perform basic low-freq signal analysis but it takes all CPU time)ĭo you have experience with ultrasound modules ? Do I need an amplifier ? Are there modules that can do basic sound processing so I can offload that work from the Arduino ?Įdit : I looked at this article : SCIRP Open AccessĪt the frequencies we are talking about, transmission loss is very small, so I will only take into account propagation losses. Ultrasound seems far-fetched, but I still an ultrasonic tx/rx pair (ordered ). The problems here are the size of the compartment, the weight of the cable (I have to transmit power, ground + 6 channels, so 8 cables). It looks like the only option would be to put the receiver module in a watertight compartment that floats to the surface, linked to the sub with a cable. It seems the longer the antenna, the lower the efficiency. However, if I submerge the whole antenna and just leave the last 30cm out, the signal is instantly lost. If I keep the antenna over the water as much as possible, I can lower the submarine up to about 30cm before losing connection. It looks like thelimiting factor here is the distance between the receiver and the first bit of antenna that is over the water. I soldered two wires to my 2.4GHz receiver and let them float to the surface while the submarine was under water. Xbee is a bit too expensive for my budget, but I did consider extending a receiver antenna. Bandwidth is not really an issue, but I couldn't find any transmitters/receivers with such a low frequency (and I suppose the antenna size would start tu be an issue) Do you know if I can find any modules that provide a lower frequency ? On DigiKey I could not find any lower than ~300 MHz Isaac96 : I was thinking of using VirtualWire, it seems like the most used option. I'll give it a shot and keep you informed Wwbrown : Sorry to hear that it probably won't work. I also looked at AM transmitters, but again I couldn't find an appropriate receiver, and I'm not sure how to amplifiate the TX signal I know the usual solution is hydrophones or lasers, but it seemed a bit overkill, and I don't have the time or the patience to build amplifying circuits, so I'll stick with the nice arduino modules if I can. ![]() I should receive it in about 10 days, I will keep you posted on how this performs. I looked desperately for a 41 MHz transmitter but could never find the matching receiver, so I gave up. I know the smaller the frequency the better, but this is the lower I could find. Using a long antenna that reaches up to the surface (but I don't want to damage the nice antenna of the receiver, and I don't know if it will work) ![]() The range is about 10cm underwater (I expected worse), then the signal drops. I tried a 2.4 GHz remote ( FlySky FS-i6 2.4G 6CH AFHDS RC Radio Transmitter With FS-iA6 Receiver for FPV RC Drone Engineering Vehicle Boat Robot Sale - Banggood USA-arrival notice), like every newbie, and it failed miserably (maybe I should have researched a bit more before buying.) ![]() I would need to send about three servo channels at least four times per second, plus three binary channels (108 bps at the very least) I am trying to control a RC submarine under 2 meters of clear water (or very slightly salted, much less than the sea). ![]()
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