EM environment of a ship

Discussion in 'General Electronics Chat' started by jerseyguy1996, May 25, 2013.

  1. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    I'm curious if anyone may have any insight for me. I designed an arduino GPS shield around the Maestro A2035 GPS module and it mostly works great. I recently went on a cruise and took the GPS module with me to log the entire trip on an SD card. Almost immediately I started having problems with it. For one, the serial data coming from the GPS module started have sporadic errors in it. Eventually it degraded to the point where the arduino was just reading a whole bunch of junk from the serial port. I thought for sure the GPS module had experienced some sort of corruption in its program memory but now that I am home and away from the ship, the thing is working flawlessly again. Are my problems likely the result of the high EM environment of the ship wreaking havoc on my circuit? If so, how do people design circuits to resist those types of external influences?
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The various transmitters on the ship may have been interferring with your GPS signal. The ship has various repeaters to relay cell phone signals, it has microwave communication, and radar and ...
     
  3. jerseyguy1996

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    Feb 2, 2008
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    It seemed like the GPS signal was okay, but the serial communication between the GPS shield and arduino was corrupted. I was using the internal UART for communication. Are UART's typically susceptible to EM?
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Not too bad unless you have some long, unsheilded wires that are good antennas. You could have lots of issues of un shielded emi on a ship. Remember, these things are registered in foreign countries and the equipment they use doesn't really have to play by any FCC rules once they hit international waters.

    Here is the description from ship-technology.com of the Carnival Miracle...

    power and Propulsion
    Carnival Miracle has a very high level of plant redundancy; at least 50% of nominal capacities remain available after any single failure.
    Carnival Miracle has diesel-electric machinery, consisting of six Wärtsilä 9L46D diesel engines, with a total power of 62,370kW, each connected to an alternator producing
    electricity to the ship's main electric network. The six 14,405kVA / 60Hz / 11,000V units are supplied by ABB.
    The propulsion consists of two fixed pitch azimuthing electric Azipod propulsion units. The brushless synchronous motors, mounted inside the pods, have double windings. The maximum output power of each motor is 17.6MW, with a speed range of 0rpm to 150rpm. The Carnival Miracle has three 1.91MW tunnel thrusters in the bow. The service speed is 22 knots and there are a pair of fin stabilisers.

    The vessel has three fresh water production plants: two 650t/day evaporators and a 200t/day FW Reverse Osmosis (RO) plant.
    The machinery is arranged into two independent parts. The main electric distribution and monitoring between the wheelhouse and control room (on Deck A) is divided and there are two separated high voltage switchboards (on Deck B) and two separate cyclo-converter rooms (on Deck B). Five of the six generators can supply all normal service rating. This arrangement allows for one engine to be out of service for maintenance
    .
    There are two oil-fired steam boilers rated at 13,000kg/h at 9bar each and six exhaust gas boilers at 2,600kg/h at 9bar each. There are also divided redundant telephone, public addressing, control and alarm systems.
    The navigation system is integrated (STN Atlas NACOS) and has a electronic chart system.
    The Carnival Miracle is classified by RINA and flagged by Panama. It has the notation *100-A-1.1-NavIL; TP with additional notations +IAQ-1, IWS, TMS, CLEAN-SEA, CLEAN-AIR, +AVM-DPS.
     
  5. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    Well I thought it was working okay but after about an hour of continuous running it started getting the garbage serial data again. I'm using a TI bi-directional voltage translator (TXB0108PWR) to interface the 5V arduino to the 3.3V GPS module. I'm kind of thinking that that may be the problem. Tomorrow I will feed the transmitted signal from the GPS Module directly into the Arduino and see if that fixes anything.
     
  6. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    Well I tried wiring the Tx side of the GPS Module to the Rx side of the Arduino and it worked great for a few hours and then started throwing out junk again. Any ideas on why an IC would work fine for a few hours and then just start sending out corrupt data? The IC doesn't feel hot or anything so I don't think overheating is an issue.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Can you show a printout/readout of the "junk" you are receiving?

    What is the power source? Batteries?
     
  8. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    Power source is either batteries or the 5V USB from my laptop. It doesn't seem to matter which. I have a LDO 3.3V linear regulator for powering the GPS module. I'll run the thing for a few hours today until I start getting junk and post a screenshot of it.
     
  9. piratepaul

    Member

    May 20, 2013
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    I have a GPS with a connector missing, I need to make a new connector... I want a word with you... ...?

    I my ship I have probs with ...( I am in the car just now ... back with numbers later). a regulator/charge controler... the phone talks to the reg & vice versa if the reg is open circuit... radio chaos .

    Suppress power supplies?, maybe it takes time or a cap to charge?
     
  10. piratepaul

    Member

    May 20, 2013
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    PWM current reg(LED driver) ...suppression cap charges from leakage current and kicks the PWM?
     
  11. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    I'm kind of wondering if my serial communication indicator LED is causing the problems. I have it set up as 3.3V -> 1K Resistor -> LED -> Tx so when the UART pulls the line low the LED will light up indicating communication happening. Could this cause problems? If so, I still don't get why it would work for a few hours and then start having problems.
     
  12. piratepaul

    Member

    May 20, 2013
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    UART driver? I am struggling with the terminology.. (sorry bout the spellin not much good with this sofware stuff)

    May be there are 2 frequencies Tx and Rx, inerference is a single frequency, a suppressor cap charging slow could account for the time aspect, frequency of resonance the Tx Rx bit...

    Tickling (as in tummy tickle) a PWM or ???? is hard to detect... may be try turning everything on... I asume you have tried turning things off.

    Off the top of my head thats about it... sorry.

    Any chance of taking a stab at a prob for me I will start a new thread ''GPS wires'' in general electronics chat in a short while... dont want to interupt this unless I think of something useful. Tar&stuff.
     
  13. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    While very impressive I have serious doubts that most of it could be traced as the origin of EMI.

    They have microwave... Have they?
     
  14. piratepaul

    Member

    May 20, 2013
    35
    2
    CMOS batt.
     
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