Wireless instrument sensors - straight to computer?

Discussion in 'OnBoard Electronics & Controls' started by DennisRB, Oct 23, 2013.

  1. DennisRB
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    DennisRB Senior Member

    I have been looking at the prices for the usual brands of wireless systems and the prices are nothing short of ridiculous. Clearly this is just a boat tax as the technology is very cheap these days. I am typing this on my $15 wireless keyboard.

    Is there anyway we can eliminate most of the gear and wiring so that just wireless sensors can be used to stream information straight to say, and Ipad or Laptop? Most of us already own a ipad/laptop. All that I actually see the need for is some sensors that would output a signal readable by the device then some software to display it.

    In theory this sounds very doable and cheap. Has anyone experimented with this sort of thing? Can usual sensors be plugged into something that would convert the signal to wifi/or bluetooth or something?

    There has to be a way with some clever thinking.
     
  2. michael pierzga
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    michael pierzga Senior Member

    I think the term is nmea multiplexer. data in, data out bluetooth or wifi. Then you need a program on your laptop that makes sense of all this incoming info.

    Best if you talk to a marine electronics pro. http://www.digitalyacht.co.uk/

    Wireless wheelhouses are the fashion these days .They could tell you of the challeges you may face.
     
  3. CDK
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    CDK retired engineer

    At first glance this seems simple and straightforward. However, wireless devices must have unique addresses, passwords etc. and they need power, so there will still be wires unless you want to rely on a couple of AAA batteries in a moist environment.
    And of course the receiving end needs a program that shows the received data in a sensible way.

    Because of all this, the industry has decided to use nmea 2000 and a few derivatives where all talkers and listeners use the same data wires and dc power, so there is just a single 4 wire cable supporting the whole system.
     
  4. michael pierzga
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    michael pierzga Senior Member

    The present networked system, with wires and junction boxes and dedicated hardware works well.

    Why would you want to change it ? Toys like an ipad arent robust enough to serve as mission control. They are handy in many situations. I have one....nice toy...the battery is always dead, touch screen is goofy, barely daylight readable and dont get them wet

    When using output directly from a sensor you face a dampening problem. The old stand alone gear always had a menu to adjust dampening. Now with this networked gear i have problems with dampening...jumpy numbers like sog, cog...that require too much user interpretation to make sense of them.
     
  5. DennisRB
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    DennisRB Senior Member

    Thanks guys. I didn't think it would be that easy, otherwise everyone would be doing it. Still it seems more expensive than it needs to be. I think feeding the sensor with 12V will be fine as it is readily available. But the other wiring could be a PITA to install. Especially the mast head. I thought the masthead wind speed sensor could have a small 12V nicad recharged by the anchor/tri light.

    Michael, this will be the way of the future. Yes there will still be a system of usual displays at the helm for redundancy. I know that when I am passagemaking I am NOT standing at the helm 99% of the time. I am where ever I feel most comfortable. It would be great to have all the ships info available on my portable device where ever I feel like sitting or lying at the time.

    Software needs to be designed to take care of all the inputs. Perhaps a opencpn plugin. Your damping prob could easily be solved by software. Not by me of course :D But by anyone who knows what they are doing with software.
     
  6. pdwiley
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    pdwiley Senior Member

    I was part of a team that built a very successful system 15 years ago but it wasn't really low power so dubious for small craft.

    In essence we fed the RS232 or analog data to terminal servers, turned it into tcp/ip data streams, massaged & combined it as we saw fit then re-broadcast it in a variety of forms. We used a combination of fixed wiring and wifi. Worked fine and I still have all the source code but as I said, not trivial for a small boat. We never had to worry about our electrical power budget.

    PDW
     
  7. michael pierzga
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    michael pierzga Senior Member

    The marine electronics industry certainly wants to promote wireless equipment.

    The installation is simple. Refitting a new masthead sensor and cable is difficult and may be impossible. If it were wireless the installation would be simplified.

    Whether this trend to wireless is good I don't know.

    With wired gear and a voltmeter I can trouble shoot. With wireless its impossible.
     
  8. pdwiley
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    pdwiley Senior Member

    No it is *not* impossible, it just requires different knowledge and tools.

    PDW
     
  9. CDK
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    CDK retired engineer

    The masthead anemometer is a special case. It generates power instead of using it, so a wireless version would be great there.
    For home use there are "weather stations" with wireless outside sensors but somehow the manufacturers feel the need to use plastics that hardly survive one season. Modifying a marine one by adding a small transmitter seems the way to go.
     
  10. michael pierzga
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    michael pierzga Senior Member

    Seems like everything is wireless these days. Modern motoryachts no longer need wing stations for docking manovoers...the operator simply uses a handheld wireless control system

    I need to replace my anchor chain counter sensor...when I went to the marine store the new generation chain counters were wireless.

    good or bad...difficult to say.

    I do know that a wired proximity switch lasts for many years, I can rapidly check its function , troubleshoot and I can purchase a new proximty switch and cable at most elecrical supply shops.

    wireless transmitters ? how will i replace this
     
  11. tspeer
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    tspeer Senior Member

    I think the wireless sensor systems typically use a proprietary protocol. I suppose you could sniff the ether and figure out what it is, then write your own software to acquire the signals.

    I have a TackTick system on my boat, with the NMEA interface, to which I added a ShipModul 41BT Bluetooth multiplexer.
    [​IMG]
     
  12. DennisRB
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    DennisRB Senior Member

    That looks like a very impressive system, prob cost around $5K. I take it this is a full NMEA2000 system, is there any 0183? The antenna looks like it is wireless in the schematic. But it needs to be wired doesn't it?
     

  13. tspeer
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    tspeer Senior Member

    It's actually NMEA 0183 for the NMEA interface, IIRC. Most of it is all internal to to the TackTick system. The way I've drawn the diagram is a little misleading in that I've shown the wireless TackTick communication as though it was a bus. That was convenient for the graphics, but it would probably be more accurate to show all the data as flowing point to point. I discovered that physically when I picked a bad location for the NMEA interface unit. The display was showing all the data correctly, but I couldn't get wind data to come out on the data stream. When I relocated the NMEA interface to the aft cabin, all was well. It turned out my first location was under the stainless steel sink, and it was shielded from the masthead unit. It turns out the NMEA interface has to be able to "see" all the other transmitters in order to receive all the data.

    This also means that each display or other unit is doing its own computations. So, for example, true wind speed and direction on one display is not necessarily the same as on another display. They would both be based on data from the masthead unit and speedo, but both displays would be doing independent calculations. It's not like the true wind speed and direction are computed just in one unit and then transmitted to the other units. Each unit is pulling all of its raw data from the ether and doing all of the necessary calculations itself.

    The GPS antenna was hard-wired to the NMEA interface in that version of the configuration. The NMEA interface and the compass/depth/speed interface are hard-wired to their respective sensors and also need 12V DC power. But the interface units can be located close to their sensors and you only need to run the power lines through the boat. The displays and masthead unit are solar powered, so they are completely wireless.

    I have since changed the configuration to add a broad-band radar and chart plotter. The TackTick GPS antenna was replaced by a different GPS unit that communicated directly to the chart plotter and from there to the rest of the system. I was also able to have the autopilot linked with the chartplotter, so now it will follow a course between waypoints automatically. So now there are two sub-nets linked together. There's the TackTick wireless network for the sailing sensors, and the GPS/chartplotter/radar/autopilot wired network.

    Adding instrumentation is expensive, but I think the TackTick system provides a lot of functionality for the money.
     
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