Solid state radar #2: the Doppler effect

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.

16 Responses

  1. Dan Corcoran (b393capt) says:

    Very cool. I like the green for targets moving, in addition to red for targets moving towards us.

  2. Henry Castledine says:

    Looks like a game changer, Raymarine and Navico better not wait too long!

  3. paul shard paul shard says:

    I wonder if larger ocean swells (which would be moving at greater than 3 knots) would show up with the Doppler function?

  4. Derek says:

    I’m hoping that manufacturers will provide some choice in the colors for coming/going targets.
    Something like 1 in 12 males (lower for females) have a color vision deficiency and most of these have difficulty with red/green. It would be a nice option to be able to select another combination like red/blue.

  5. Ben Ellison Ben Ellison says:

    Thanks, Dan! Garmin also provides LOTS of palette choices, and that may answer Derek’s concern. I can’t address Paul’s concern but isn’t the solution easier if the radar can resolve target speed on every pass?

  6. Joe says:

    I too really need to see this newer technology outside of Florida and flat water conditions. Lets see it in the ocean, or when large barges go by with nice wakes.

  7. Sheldon Haynie says:

    A “good” Doppler needs a speed gate function, where the user can set a cut off below and above which they are not interested. E.G if you are navigating near a bridge you might want to exclude any returns over 40 kts as unlikely to be of maritime concern, or less than “X” kts that would be likely stationary. Any wave that was significant enough to show an individual return, should be highlighted. If I was out in the fog and there was a large Wake, breaking or rogue wave coming, it would be nice to have it alarm. Some type of sensitivity control should already dampen the repeating signals of sea clutter.

  8. I’m looking forward to these products making out and into the hands of folks so that we can start getting even more data about how they work in real work conditions. I’m glad Raymarine has released the Quantum solution since I’m mostly a Raymarine boat, and interested in how WiFi and doppler influence radar in general to continue innovating and becoming more modern, like the rest of boating electronics appear to be doing.

  9. Howard says:

    Keep up the information flow. I am going to wait for an open array Furuno.

  10. One of the screenshots shows an SOG of 3 knots. From these I jump to he conclusion that all were at slow speed. From here I go further and speculate that red means 5 knots or more of approach velocity — and everything else is green: rocks, kayaks and other slow moving boats, and things moving away. I’ve been on collision corses with other vessels with way less than 5 knots of approach speed. I think I would rather know what is moving and what is not. What does the screen look like when moving at 10 or 20 knots? I also assume that the doppler is relative to your own boat, not corrected to be relative to the ground.

  11. Leo Starrenburg says:

    Some 30+ years ago I serviced, among other things, X-band Doppler field reconnaissance radar sets. Small and ‘portable’ these were used by cavalry units to watch over bits of battle field. A nice detail: the processed echo’s were made audible so the operator could hear what caused the echo’s. Tanks, trucks, a marching platoon or a couple of soldiers could all be distinguished. I used to test repaired units near a lake, can still hear the audio of a row boat 😉

  12. Ben Ellison Ben Ellison says:

    Hi Norse: No, not all the screenshots were taken at slow speed, and I’m not sure why you’d assume that the target speed is relative to your own boat speed. I don’t know for absolute sure, but I think it’s true target speed, 3 knots on the Furuno NXT screens, 5 knots on the Garmin Fantom screens.
    I also don’t know what exact parameters either company is using to paint Red for target moving your general direction, but over and over it made sense when you checked what the real target was doing versus the radar image.

  13. Thanks Ben for the answers to my questions. I know from following the link you gave for the Garmin avionics weather radar that Garmin can correct the display for true taget speed; it wouldn’t be useful if it didn’t. On the other hand, it’s over $20,000. The Doppler effect measures relative motion, so it’s good to hear that these marine doppler radars do correct it to ground speed.

  14. Karl says:

    Will Doppler obsolete ARPA/Marpa?

  15. Dan Corcoran (b393capt) says:

    Will MARPA be enhanced by Dopler, yes
    Will ARPA obsolete, MARPA, yes.
    Will ARPA be enhanced by Dopler, yes

  16. mike says:

    Does anyone know if Simrad will be adding this same feature to the 3g/4g? Do you think it would be a software upgrade that could be uploaded?

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