NMEA 0183 lives: Digital Yacht GP150 DualNav & Furuno IF-NMEA2K2 Converter

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

12 Responses

  1. Ben Ellison Ben Ellison says:

    Incidentally, Digital Yacht’s GPS 150 can receive 50 satellites at once, while the Garmin 19x has ‘only’ 32 channels. DY thinks that more channels may give its dualnav sensor greater accuracy.

  2. Richard C says:

    At the NMEA conference, was there any mention of a new PGN for an anchor chain counter? I know this is almost primitive compared to the dual GPS mentioned here, but oh how we all could use the anchor chain deployment length going directly into NMEA 2000.

  3. Hmm – only if you actually have that many satellites in view. Not likely with any one system, though I suppose it’s possible with multiple systems. In my experience, satellites out at the fringe contribute little to overall accuracy – whether that’s due to basic geometry or BER problems, I don’t know.

  4. Karl says:

    US GPS is actually two systems: the “civilian” version we all use worldwide, and a separate band and protocol for US/NATO usage which is far more precise. The civilian version can be turned off by the flick of a switch by govt., and I would assume the Russian system follows suit…since it has both high precision and standard precision components. In the event of a major international military action, expect all consumer receivers to be useless, regardless of how many satellites are in view.

  5. Bushman says:

    Actually, the number of channels has almost no effect on accuracy of single-frequency receiver after some value, because uncertainty in measurements could be lowered, but not eliminated, while we know nothing about things, affecting signal from each satellite.

  6. madscientist says:

    Karl, I think this GNSS bogeyman is somewhat false. GNSS is now so ingrained in society that turning it off, would be like turning off the electricity.
    Secondly the military uses a lot of civilian code only receivers as well.
    Thirdly I believe that the C/A code is need to acquire the first fix , and then the P code is used. So I don’t believe one can be switched off on its own. Remember civilian use of GPS was only as an afterthought and surprisingly the C/A positioning turned out better then predicted, which is why SA got put in.
    Today the key is to selectively deny GNSS coverage , rather then turn off the system
    Ultimately we will have 3-5 GNSS systems operational over the next few years. I would have no concern about it being turned off.
    and as a final thought, in a war that forces 4 or 6 GNSS to shutdown , or they are blown up, the last thing on your mind will be your LAT LON. !!!

  7. Richard D says:

    A very good explanation of the value of large numbers of GPS receiver “channels” can be found at:
    Cheers, Richard D

  8. Dan Corcoran (b393capt) says:

    That is a great explanation of the value of more channels RichardD, Thanks for sharing.

  9. Ben Ellison Ben Ellison says:

    I agree with Dan. It also makes sense with the fast position acquisition and high performance in tough places that I’ve experienced with the little Bad Elf Pro, which is a 66 Channel GPS receiver.

  10. Ben Ellison Ben Ellison says:

    Interesting BBC radio documentary on the fragility of GPS system (thanks, Bob!):

  11. Richard,
    Did you learn anything more about a PGN for anchor chain length?
    Douglas Cochrane
    M/V Orion, N57-25

  12. Richard C says:

    When I researched AutoAnchor, the company that makes chain counters, everyone told me there are no PGN’s for anchoring. I’m told this is why they use NMEA 0183 in only one product – the 601. So far, I haven’t read or heard anything different. Too bad because anchoring is such a critical evolution and knowing how much chain to deploy is a safety issue. Establishing a PGN would open the door to displaying the chain count on any number of devices.
    At one time both Garmin and AutoAnchor had published information about displaying the chain count on a GMI-10, (using 0183). All this wording has disappeared from their literature.
    Richard C

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