Standard Horizon HX851 users: compass functionality?

I've got a GOFMC (good old fashioned magnetic compass) that I keep in my PFD, but also just picked up the HX851 and saw it's got a compass that ties in with its way-points.  I'm about to call S.H. for some help on it, but thought I'd ask here to see if anybody's got experience with using this radio's compass:

Do you know if the built-in compass is magnetic or derived from the GPS?  I can't seem to get the damned thing to lock N to north (in spite of setting to north always up in the menu).  The compass seems to randomly bounce around regardless of movement or lack thereof (trying this on land, outside, BTW).

Does the radio require horizontal or vertical orientation for the compass to function? No mention of this in the manual included with the radio, and it doesn't seem to matter in my tests.

Lastly, how responsive is the compass display? I can't tell if my grief is operator error (likely), a defective unit/ documentation (possible), or super-sluggish refresh rate on the display  (remotely possible).

Other than this, it appears to be a solid radio, albeit freaking huge.

Thanks,

Ron

Somehow I believe the compass is based on GPS which will require motion in a particular direction for a distance to register a heading.  I may be totally wrong though.

Somehow I believe the compass is based on GPS which will require motion in a particular direction for a distance to register a heading.  I may be totally wrong though.

From what I've seen, this would explain the weird behavior of my radio; I've not tried it out over any appreciable distance.

If you've ever tried to use the compass or "highway" feature on a GPS or GPS/FF combo, then you'll understand the oddity you are seeing.  The GPS requires a perceivable distance greater than its margin of error in order to see that you are moving in a particular direction.  This becomes especially important to GPS users on boats with radar & autopilots.  They have to add a separate fluxgate compass to combat this situation. 

If you've ever tried to use the compass or "highway" feature on a GPS or GPS/FF combo, then you'll understand the oddity you are seeing.  The GPS requires a perceivable distance greater than its margin of error in order to see that you are moving in a particular direction.  This becomes especially important to GPS users on boats with radar & autopilots.  They have to add a separate fluxgate compass to combat this situation.

Cool, thanks!  I'll take it out with the dogs on their walk next time to see if it behaves more predictably, and will report back.

If you've ever tried to use the compass or "highway" feature on a GPS or GPS/FF combo, then you'll understand the oddity you are seeing.  The GPS requires a perceivable distance greater than its margin of error in order to see that you are moving in a particular direction.  This becomes especially important to GPS users on boats with radar & autopilots.  They have to add a separate fluxgate compass to combat this situation.

Cool, thanks!  I'll take it out with the dogs on their walk next time to see if it behaves more predictably, and will report back.

Be sure to post your findings...

The accuracy seems to vary with different brands and models. I have an old Magellan handheld that will adjust the compass after a few steps. I haven't paid much attention to the compass on my FF, but the speedometer fluxuates quite a bit so I wouldn't be surprised if the compass was less than accurate.

I wandered around the neighborhood last night with the dogs and the HX851 in compass display mode.  Definitely GPS derived, and fairly sluggish. Not too bad on the average, but no movement=no compass.

I think it'd be a good idea to use this in conjunction with a magnetic compass.  Especially if you're in a current or wind and getting blown / pushed badly. 

I wandered around the neighborhood last night with the dogs and the HX851 in compass display mode.  Definitely GPS derived, and fairly sluggish. Not too bad on the average, but no movement=no compass.

I think it'd be a good idea to use this in conjunction with a magnetic compass.  Especially if you're in a current or wind and getting blown / pushed badly.

My guess the reason there is no magnetic compass is because there is a speaker, which is driven by a magnet 

GPS is slow to respond with slow movement.  You need to run around the block ... really fast.

It also depends on the hZ rate their GPS operates at.  1hz would be 1x a second.  I can notice a huge difference in my Lowrance unit (same unit) when mounted on my kayak at 5hz vs. on by boat with the external antenna @ 10hz.

I just downloaded the manual for that radio but didn't see any specification for gps "speed".

The GPS on my FF has led me around in circles before, since it didn't update quickly enough for my corrections while paddling in the fog.  Headed out the SC harbor, and almost landed at the beach to the left!     Now I always have my compass on deck.  It's far easier to go in a straight line looking at a compass.

  It's far easier to go in a straight line looking at a compass.

+1  Yes it is!

But then there's the possibility of cross drift.

My guess the reason there is no magnetic compass is because there is a speaker, which is driven by a magnet 

d'oh, of course.  Unless they're going to use a piezo speaker, it'd have to be.  I should have thought of that.  I'm a damned audio engineer and work with speakers all day.

LOL  If you happen to come across an extra Sennheiser G2/G3 or similar lavalier setup for the top of my DSLR please drop me a PM

LOL  If you happen to come across an extra Sennheiser G2/G3 or similar lavalier setup for the top of my DSLR please drop me a PM

Will keep my eyes open for one. Oddly, they don't hit the used market outside of ebay all that often. At least not in my travels.