We made the world's smallest sonar modem

Greetings to you, our dear habread reader! 3r33814. 3r33817.  3r33825. 3r3675. “Thus the Spirits diminished, and the palace of 3r33817.  3r33825. Holds odd swarms of
 3r33825. Spacious. ”
 3r33825. (C) John Milton, Lost Paradise
3r33817.  3r33825. 3r3678. 3r33817.  3r33825. Adherents of the dark kagala of underwater communication and navigation work day and night to bring this very underwater communication and navigation to the masses, and today one of them, as promised, will report on the work done and the progress achieved. 3r33817.  3r33825. 3r33817.  3r33825. We made the world's smallest sonar modem 3r33737. 3r33817.  3r33825. 3r33817.  3r33825. Traditionally realizing that the topic of hydroacoustic communication and related problems is far from familiar to everyone, I propose a set of ours (and not only) 3r31717.  3r33825.
previous articles 3r349. 3r350. Session video transmission sound through the water exposing 3r33817.  3r33825. 3r3355. Underwater GPS from scratch for the year
3r33817.  3r33825. Underwater GPS: continued 3r33817.  3r33825. 3r33700. Underwater "GPS" on two transceivers
3r33817.  3r33825. 3r3104. On the effect of cyanobacteria on the speech functions of the president 3r373719. 3r33817.  3r33825. Navigation under water: direction finding - not direction finding, you are doomed to success 3r33817.  3r33825. 3r375. And also with a great review article @akuzmin about hydroacoustics 3r-3737. 3r33817.  3r33825.
3r33817.  3r33825. 3r33817.  3r33825. Briefly mention that we have here 3r3737. 95% of the ocean remains unexplored, and the difficulty is not only in the fact that we are already we cannot live under water, but also because radio waves do not propagate under water (however adequate frequency), and accordingly everything that is possible on earth and in the sky using radio communication becomes almost impossible even under a thin layer of water, and yes, there is still mostly dark and dull. 3r33817.  3r33825. 3r33817.  3r33825. Humanity is trying to get out, and today the only more or less widespread alternative to radio communications under water is acoustics, or more precisely hydroacoustics. With the help of sound waves, which by the way, spread in the water five times faster than in the air:
 3r33825. 3r395.  3r33825. 3r3115. 3r3398. exchange voice messages r3r3719. . Voice messaging devices are among the simplest and quite common in narrow circles. Engaged in the development, for example 3r3-3100. OTS 3r3373719. , 3r3102. OceanReef
, and from last year and we are ;
 3r33825. 3r3115. Bearing and determine the location of underwater objects using 3r3111.
long-range navigation systems. ;
 3r33825. 3r3115. 3r3116. Engaged
surveying the bottom, searching for fish and various submarines; 3r33817.  3r33825.
 3r33825. 3r3122. 3r33817.  3r33825. And they simply transmit digital data, and at the same time, it is often a good deal of our time to combine data transmission with navigation. 3r33817.  3r33825. 3r33817.  3r33825. Devices with the help of which digital data is transmitted through water is called (oddly enough) hydroacoustic modem. 3r33817.  3r33825. 3r33817.  3r33825.
Transmitting data by sound through the water is difficult, but you can 3r33814. 3r33817.  3r33825. To understand why this is difficult, imagine that you are looking through a babbling brook at a newspaper lying on the bottom and are trying to read it. All that you can make out through the running ripples and glare - the title. Strongly straining your eyes, you may be able to sort out (even, rather, guess) the text of the subtitles, but you will understand what is written in the columns with great luck, when the ripples are smooth for a moment and a thin layer of laminar water flows between the eye and the text. 3r33817.  3r33825. 3r33817.  3r33825. Sound in water propagates nonlinearly, undergoing bends (refraction), reflections, addition and subtraction of reflected copies of a signal (reverberation and multipath propagation), Doppler shift as well as stretching and compression of the spectrum. 3r33817.  3r33825. 3r33817.  3r33825. Following our analogy, the larger the heading is, the easier it is to read, that is, the slower the transmission rate is, the more reliable the connection is, in general, it can be compared to the noise-resistant coding (it takes time and additional information). , and read a very small text can only be in good conditions. 3r33817.  3r33825. 3r33817.  3r33825. People close to radio communication will rightly notice that all the difficulties listed are inherent in varying degrees and radio channels, but the main differences are that in hydroacoustics for data transmission, we can access the band somewhere from 5 to 100 kHz with a very big stretch ( in reality, it is noticeably less), and control to the head: if (plus or minus) to transmit data in the 5-15 kHz band, having worked hard for 10–20 km, then in the 80–100 kHz band, it is possible to reach a range of 1 km with a fair fractions of luck, which is associated with a strong non-uniformity of attenuation i sound waves of different frequencies. 3r33817.  3r33825. Well, yes, the speed of sound is a little less than the speed of light - only 20?000 times. 3r33817.  3r33825. 3r33817.  3r33825. To illustrate the capabilities of modern sonar modems, here is a 3r3155 tablet. the dissertation
(page 54 for PDF) Bridget Benson, very popular with in vain trying to make a hydroacoustic modem "on the knee." The label is somewhat outdated, because this work dates back to 201? and, unfortunately, I cannot correct it based on rumors, so I bring it intact: 3r33817.  3r33825. 3r33817.  3r33825.
 3r33825. 3r33351.  3r33825. 3r33333.  3r33825.
Manufacturer
 3r33825.
Modem
 3r33825.
Bandwidth, kHz
 3r33825.
Power consumption (transmission), W
 3r33825.
Range, km
 3r33825. 3r33553.  3r33825. 3r33375.  3r33825.
 3r33825. 3r33333.  3r33825. 3r33550. Aquatec 3r33551.  3r33825. 3r33550. AQUAModem
 3r33825. 3r33550. 8-16
 3r33825. 3r33550. 20 3r3-3551.  3r33825. 3r33550. 10 3r3-3551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. DSPComm
 3r33825. 3r33550. AquaComm
 3r33825. 3r33550. 16-30 3r33551.  3r33825. 3r33550. varied
 3r33825. 3r33550. 3 3r???.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. TriTech
 3r33825. 3r33550. MicronModem
 3r33825. 3r33550. 20-24 3r33551.  3r33825. 3r33550. ???r33551.  3r33825. 3r33550. ???r???.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. WHOI 3r3551.  3r33825. 3r33550. MicroModem
 3r33825. 3r33550. 25 3r3-3551.  3r33825. 3r33550. 50 3r3-3551.  3r33825. 3r33550. 1-10 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. Benthos
 3r33825. 3r33550. ATM885 3r33551.  3r33825. 3r33550. 16-21 3r33551.  3r33825. 3r33550. 28-84 3r33551.  3r33825. 3r33550. 2-6 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. EvoLogics
 3r33825. 3r33550. S2CM48 /78 3r33551.  3r33825. 3r33550. 48-78 3r33551.  3r33825. 3r33550. 2.5-80 3r33551.  3r33825. 3r33550. 1 3r???.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. LinkQuest
 3r33825. 3r33550. UWM2000H
 3r33825. 3r33550. NS
 3r33825. 3r33550. ???r33551.  3r33825. 3r33550. ???r???.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. UCSD 3r3-3551.  3r33825. 3r33550. UCSDModem
 3r33825. 3r33550. 40 3r3-3551.  3r33825. 3r33550. 1.3-???r33551.  3r33825. 3r33550. ???r3r3551.  3r33825. 3r33553.  3r33825. 3r33555.  3r33825. 3r33557. 3r33817.  3r33825. 3r33817.  3r33825.
 3r33825. 3r33351.  3r33825. 3r33333.  3r33825.
Manufacturer
 3r33825.
Modem
 3r33825.
Power consumption (reception), W
 3r33825.
Modulation
 3r33825.
Baud rate, bps
 3r33825.
Price, $ 3r3333371.  3r33825. 3r33553.  3r33825. 3r33375.  3r33825.
 3r33825. 3r33333.  3r33825. 3r33550. Aquatec 3r33551.  3r33825. 3r33550. AQUAModem
 3r33825. 3r33550. ???r33551.  3r33825. 3r33550. DSSS 3r33551.  3r33825. 3r33550. 300-2000 3r33551.  3r33825. 3r33550. 7600 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. DSPComm
 3r33825. 3r33550. AquaComm
 3r33825. 3r33550. varied
 3r33825. 3r33550. DSSS /OFDM 3r3-3551.  3r33825. 3r33550. 480 3r33551.  3r33825. 3r33550. 6600 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. TriTech
 3r33825. 3r33550. MicronModem
 3r33825. 3r33550. ???r???.  3r33825. 3r33550. DSSS 3r33551.  3r33825. 3r33550. 40 3r3-3551.  3r33825. 3r33550. 3500 3r???.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. WHOI 3r3551.  3r33825. 3r33550. MicroModem
 3r33825. 3r33550. ??? /2 3r???.  3r33825. 3r33550. FSK /PSK
 3r33825. 3r33550. 80/5400
 3r33825. 3r33550. 8100-9400 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. Benthos
 3r33825. 3r33550. ATM885 3r33551.  3r33825. 3r33550. ???r3r3551.  3r33825. 3r33550. FSK /PSK
 3r33825. 3r33550. 140-15360 3r33551.  3r33825. 3r33550. 7200-11000
 3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. EvoLogics
 3r33825. 3r33550. S2CM48 /78 3r33551.  3r33825. 3r33550. ???r???.  3r33825. 3r33550. S2C 3r33551.  3r33825. 3r33550. 15000 3r???.  3r33825. 3r33550. 12500 3r33551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. LinkQuest
 3r33825. 3r33550. UWM2000H
 3r33825. 3r33550. NS
 3r33825. 3r33550. Proprietary 3r33551.  3r33825. 3r33550. 9600 3r33551.  3r33825. 3r33550. 7000 3r3-3551.  3r33825. 3r33553.  3r33825. 3r33333.  3r33825. 3r33550. UCSD 3r3-3551.  3r33825. 3r33550. UCSDModem
 3r33825. 3r33550. ???r???.  3r33825. 3r33550. FSK 3r33551.  3r33825. 3r33550. 200
 3r33825. 3r33550. 350 * 3r33551.  3r33825. 3r33553.  3r33825. 3r33555.  3r33825. 3r33557. * Component cost estimate only
 3r33825. 3r33817.  3r33825. What has changed since 2010? Benthos was bought by Teledyne, Aquatec no longer does an acoustic modem (now it does only optically at a distance of 1 meter), and EvoLogics modems, according to rumors that have reached me, have dropped in price significantly. But the most global change from my point of view happened quite recently: sonar modems 3r-3562. appeared r3r3719. on alibab-e. Priced around $ 1000- $ 2000 each. In China, there is technology, and most likely it has moved into the category of civilians. The gentlemen from the tablet accept new members to their ranks. 3r33817.  3r33825. But so far, slow Chinese manufacturers have just released devices priced at $ ?000- $ ?000 apiece, experienced DSPComm with modems from $ ?600 has long been 3r-3666. wrote 3r3373719. on their website that their goal is modems cheaper than $ 1000. 3r33817.  3r33825. 3r33817.  3r33825. 3r33817.  3r33825.
People try to make a cheap hydroacoustic modem 3r33814. 3r33817.  3r33825. And the key word here is “cheap” - you just need to score in Google “Low cost underwater acoustic modem”. If we drop the pile of theses, suspiciously closely repeating the thesis of B. Benson, then there will still be a sufficient number of interesting projects. Interesting in my opinion generalization 3r33737. did the Spanish comrades. In many ways, very honest, without any special attempts to embellish something. 3r33817.  3r33825. 3r33817.  3r33825.
But back to the topic of article

3r33817.  3r33825. The mentioned Chinese products scare with their thoroughness: F120x60? weight 12 kg, 40 watts of the transmitter push data with speeds from 140 to 1200 bps at a distance of up to 20 kilometers. With regards to the transmission rate - I recommend always to look at the lower limit of the range. 3r33817.  3r33825. 3r33817.  3r33825. The smallest (and cheapest) modem of those that are presented in the plate - 3r-3592. MicronModem from the English spin-off company New Castle University has dimensions of F56x79 mm, dry weight 235 grams and according to the manufacturer can transfer user data at a speed of 40 bps to a distance of 500 meters. 3r33817.  3r33825. Not bad, but in 2016 we released our 3r3-3596. RedLINE
which, with dimensions of 64x62 mm and a dry weight of 360 grams, can transmit digital data at a speed of 80 bit /s over a distance of up to 8000 meters, while at the same time costing much less than a competitor, even with a relay function. In many ways, so tightly packaged "spirits in the palace" happened thanks to the efforts of 3r33620. StDmitriev
and a bit of mine. Our idea then took shape in a whole 3r3-3600. Patent 3r33737. . 3r33817.  3r33825. 3r33817.  3r33825.

Looking back

3r33817.  3r33825. Let us ask ourselves, what does a modem consist of? As a rule, from a transceiver antenna made of one or several piezoceramic rings, a power amplifier, a preamplifier and filters, as well as some kind of digital signal processor. It seems not rocket science? But after all, in a rocket, the cost of all materials and aggregates is only less than 10% of the cost of the rocket itself. 3r33817.  3r33825. While the technology has not gained mass status - it remains not cheap. 3r33817.  3r33825. 3r33817.  3r33825. And we want to buy a hydroacoustic modem was no more difficult than to buy an Arduino, GPS or radio module. 3r33817.  3r33825. 3r33817.  3r33825. What are we doing for this? Continuing to exploit our patent 3r33620. StDmitriev
this time “pushed the spirits” into the center of an even smaller size, and I, respectively, wrote down a new firmware that could take full advantage of the resulting record hardware. 3r33817.  3r33825. 3r33817.  3r33825. Meet this uWAVE - the smallest and cheapest in the world hydroacoustic modem
 3r33825. 3r3630. 3r33817.  3r33825. Now the spirits are cramped in a cylinder of size F40x45 millimeters, the weight of which does not exceed 160 grams. Hissing spirits allows you to transfer data at a speed of 78 bps over a distance of up to 1000 meters. And the modem itself can be powered even from USB. 3r33817.  3r33825. 3r33817.  3r33825. The following photo size comparison of RedLINE (yellow) and uWAVE (red):
 3r33825. 3r33817.  3r33825. 3r33817.  3r33825. But this is not all: the modem supports not only the transmission via so-called transparent channel with code division of subscribers, but also a command mode in which you can remotely request the depth, temperature (there is a built-in sensor on board) and the power supply of the remote subscriber with measurement of signal propagation time. And for the tasks of telecontrol 9 code user commands are provided. 3r33817.  3r33825. 3r33817.  3r33825. But even this is not the main thing, but the main thing is that we managed to beat our own price record and the retail price for the uWAVE modem is $ 480. This is 6 (SIX, KARL!) Times cheaper than the nearest English equivalent, with twice the range, and half the size. We neatly hope that with an increase in production, the price can be further reduced. 3r33817.  3r33825. As you can see, we met the expectations of 7.6% of those who voted in the previous 3-333700. Article 3r3719. , and this price range ranks second in the vote after the still unattainable $ 100- $ 200. 3r33817.  3r33825. 3r33817.  3r33825. [i] If someone can now be less and cheaper with the same characteristics - I give my word: I leave the profession right away! 3r3777. 3r33817.  3r33825. 3r33817.  3r33825. When I said that we reached [s] bottom 3r3373765. physical limit in size, it was meant that even if it is possible to fit all the electronics in a smaller volume, the size of the ring used will not allow to work effectively in this frequency band, and in terms of energy it will not be possible to achieve the specified characteristics. The smaller the piezoelectric element, the worse it radiates low frequencies, the higher the frequencies, the smaller the communication distance. So it goes. 3r33817.  3r33825. 3r33817.  3r33825.

And why is all this necessary? 3r33814. 3r33817.  3r33825. 3r3675. [i] “Didn’t billions of unknown skeletons in unknown graves not appealing to us, demanding or reproaching? I see billions of past human lives, in which, like sand between fingers, instantly flowed away youth, beauty and the joys of life, they demand to uncover the great mystery of time, to join the fight with it! The victory over space is the victory over time - that is why I am sure that I was right and in the greatness of the planned business! ”(C) I. Efremov, Andromeda Nebula 3r36777. 3r3678. 3r33817.  3r33825. 3r33817.  3r33825. “In the first place, it’s just beautiful ” (C) 3r33817.  3r33825. If it is serious, then recently the topic of communication with a flock of autonomous vehicles, the underwater Internet of things, and other incredible things is especially in demand. Here, colleagues do very different size autonomous devices (gliders), on which to place the product of Chinese industry weighing 12 kilograms is not that problematic, but a little impossible, and it is especially hard to feed it with the forces of this device, for example, take a look at this 3r3687. baby
3r33817.  3r33825. 3r33817.  3r33825. 3r33817.  3r33825.
On the tasty

3r33817.  3r33825. I want to tell you how we repeated the experience from the previous 3r3700. Articles 3r3373719. where they determined the geographical location of one of the modems RedGTR with the help of another similar modem, a GPS module and a Chinese radio bait boat. 3r33817.  3r33825. 3r33817.  3r33825. I quickly remade Appendix 3r3373719. so that it can work with uWAVE modems, and the onboard firmware of the boat did not even have to be changed. 3r337. Protocol 3r33737. Interfacing with modems made even easier. 3r33817.  3r33825. 3r33817.  3r33825. Due to lack of time, we did not go to our beloved
Pichugu
, but were satisfied with the fallback - 3r3373718. pond South
familiar to us reservoir, with a depth of 2 to 1.5 meters. 3r33817.  3r33825. 3r33817.  3r33825. This time the “lighthouse” was located on a raft of solid thermal insulation, and was powered by Power Bank, as can be seen in the photo:
 3r33825.  3r33825. 3r33737. 3r33817.  3r33825. 3r33817.  3r33825. working moment: 3r33838.  3r33825. 3r33737. 3r33817.  3r33825. 3r33817.  3r33825. In general, everything was expectedly earned and in the end we got a couple of tracks with an accuracy of better than 1 meter. Like this:
 3r33825. 3r3747. 3r33817.  3r33825. And so:
 3r33825. 3r3752. 3r33817.  3r33825. 3r33817.  3r33825. In the photo above is an enlarged part of the track, and the whole of it is in view of the length of the reservoir in the following photo:
 3r33825. 3r3759. 3r33817.  3r33825. 3r33817.  3r33825. Green shows the measurement track - the points where the distance to the respondent was measured, and where it lags behind the blue (boat track) the acoustic connection was broken. The reason for this is quite simple and banal - the hydrological conditions are such that it is unlikely that anyone except [s] urban mad r3r3765. we would have thought to dip such equipment in such a reservoir and try to transfer data there. 3r33817.  3r33825. 3r33817.  3r33825. In both cases, we got a deviation from the real position of the lighthouse in the region of 70-90 centimeters. 3r33817.  3r33825. 3r33817.  3r33825. This is how it looks on the screen of the console application: 3r33838.  3r33825. From the prospects associated with this branch of the device
3r33817.  3r33825. - we plan to make a direction finding antenna for working with uWAVE; 3r33817.  3r33825. - the firmware for the long-base system is already ready, in which the uWAVE modem will act as a pinger, and its location can be determined with the help of four small buoys. As soon as we get rid of the current tasks, we will develop the enclosures and boards. 3r33817.  3r33825. 3r33817.  3r33825.
Finally, 3r33814. 3r33817.  3r33825. Thank you for your attention, as always, reasonable criticism and suggestions are welcome! 3r33817.  3r33825. 3r33817.  3r33825.
P. S. 3r33814. 3r33817.  3r33825. And he is so cool, small =)
 3r33825. We got real pleasure in the process of developing our very modem itself, this is one of those moments for which we work. 3r33817.  3r33825. 3r33817.  3r33825.
P.P.S. 3r33814. 3r33817.  3r33825. The success of the company noted tea drinking, not getting out of the kayak
 3r33825. 3r33838.
3r33825. 3r33825.
! function (e) {function t (t, n) {if (! (n in e)) {for (var r, a = e.document, i = a.scripts, o = i.length; o-- ;) if (-1! == i[o].src.indexOf (t)) {r = i[o]; break} if (! r) {r = a.createElement ("script"), r.type = "text /jаvascript", r.async =! ? r.defer =! ? r.src = t, r.charset = "UTF-8"; var d = function () {var e = a.getElementsByTagName ("script")[0]; e. ): d ()}}} t ("//mediator.mail.ru/script/2820404/"""_mediator") () (); 3r33824. 3r33825.
+ 0 -

Add comment