Needing electronic compass for Radar (AIS)

[tanglewood]

Originally Posted by Wayne hoath

It’s the AIS overlay that requires the heading I believe. I have an 1835 and it gets the heading from the autopilot. If that isn’t powered on then the AIS signals aren’t overplayed onto the radar screen.

I think this is because when you display an AIS target, you are supposed to display it oriented towards it's heading. Without a heading sensor, the radar will only display heading up, and has no reference to display the AIS targets. If your Vesper has it's own display, it's probably showing everything north up, and so has a reference to orient the AIR targets against.

Re Garmin, they are one of the companies that allows radar operation using GPS COG. No wheelmark or IMO radar will allow that, insisting on heading, not COG. IMO devices require true heading. Furuno follows the commercial guidelines in their consumer products, and will only use heading, not COG.

If you are goign to buy a compass, I'd suggest getting a full rate compass, not just a fluxgate. The difference is that the rate compass also reports rate of turn (ROT). It makes a big difference with a lot of auto pilots.

[Paul Elliott]

Originally Posted by boat_alexandra

Get mpu9250 or mpu9255. These cost $4 dollars and has all rate sensors. I have nmea output, and the data is as good or better than all what people have suggested.



There is no modern fluxgate. Modern compass do not use fluxgate, they use magnetoresistors or hall effect.

OK, they don't usually use the original fluxgate design (multiple coils and permeable cores, and you can still buy these), but the magnetoresistor or Hall-effect implementations are still often called "fluxgate" compasses. This isn't a technically accurate name, but the term has become rather generic.

[Paul Elliott]

Originally Posted by sy_gilana

Can you please expand on this? do you have NMEA, RSnnn, or USB out?

The mpu9250 and mpu9255 are modern solid state / MEMS (Micro Electro Mechanical Systems) devices that contain multi-axis Hall-effect sensors, "gyroscopes" and accelerometers. (I put "gyroscopes" in quotes, because these do not use the traditional spinning gyroscope design, but rather a micromechanical angular rate sensor.) These are inexpensive chips only a few millimeters on a side, and are sometimes put in smartphones, watches, etc.

These don't spit out NMEA, that has to be done in the microcontroller that interfaces to the chip. Here's a link to a spec sheet: https://www.digikey.com/en/product-h...YaAjhXEALw_wcB