GPS 101-- CDI vs Bearing

[Balimbras]

On my first day out I got a little frustrated with my Vista. On the approach, the needle had already turned me around 180 degrees and had me heading away from the site. As I got within 20 meters, I expected to see the needle swing through an arc, allowing me to get a pretty good idea which way to proceed, but it never did. Needless to say, I didn't find the cache.

 

I think today I figured out what was wrong. I was using the GPS navigation screen set up in CDI or Course Deviation mode. In trying this out for close qusrters navigation today, whenever I walked a line parallel to a line through a target waypoint, the needle never swung to point at the waypoint, it maintained a constant direction and course deviation 'cause I was still travelling in a straight line parallel to the line between origin and waypoint.

 

Switching to Bearing indication on the navigation screen gave me what I wanted; as I passed the target, the needle swung and pointed at the target continuously as I passed it. Doh!

 

So obviously when walking an approach to a cache I should be set up in bearing mode.

 

But here's what's nagging me: shouldn't the CDI still swing in the same way as I pass a waypoint? Or should I be sending this puppy back for a check-up?

 

And I thought I knew something about navigation just 'cuz I have a pilot's license. Sheesh... shoulda been a sailor, I guess.

[Tahosa and Sons]

Use both Bearing & Heading to see where you are going. Make sure your compass is calibrated.

And what helps is to lay out a map with UTM'S,

plot your Cache before you leave. And read and plot as you go. Back up with a real compass.

 

The "Bushwhacker"

[Tahosa and Sons]

Use both Bearing & Heading to see where you are going. Make sure your compass is calibrated.

And what helps is to lay out a map with UTM'S,

plot your Cache before you leave. And read and plot as you go. Back up with a real compass.

 

The "Bushwhacker"

[OFF RODE]

GEEEZZZE and I thought I had some idea of how to use this thing ......I dont even know what your talking about...funny .. I do find caches thou...

 

"You've got to be very careful if you don't know where you're going, because you might not get there." Yogi Berra

JeepNAz@aol.com

[+Alan2]

I thought you set either bearing or course pointer on the Vista's Navigation page not CDI and then if course, the pointer will continue to show the direction to where you originally hit "go to" when starting navigation regardless of whether you passed the destination or not. The CDI will show how far you're off course. I haven't found much use for it. I always use bearing.

 

Note that anytime you again hit "go to" even while on the same destination waypoint the new course will now be equal to the bearing you are at when you "clicked". So a new course is set. Don't know what that might be good for either for most geocaching.

 

I suppose if you're flying or sailing and wanted to go around a storm, you could head up 90 degrees off course for a while then get back on course. You would follow the pointer in the correct direction but the Off Course readout would indicate how many miles you are off the original bearing to your destination. You would then head back to correct the deviation and get back on the original course (tack).

 

Does that make sense?

 

Alan

[+Alan2]

I thought you set either bearing or course pointer on the Vista's Navigation page not CDI and then if course, the pointer will continue to show the direction to where you originally hit "go to" when starting navigation regardless of whether you passed the destination or not. The CDI will show how far you're off course. I haven't found much use for it. I always use bearing.

 

Note that anytime you again hit "go to" even while on the same destination waypoint the new course will now be equal to the bearing you are at when you "clicked". So a new course is set. Don't know what that might be good for either for most geocaching.

 

I suppose if you're flying or sailing and wanted to go around a storm, you could head up 90 degrees off course for a while then get back on course. You would follow the pointer in the correct direction but the Off Course readout would indicate how many miles you are off the original bearing to your destination. You would then head back to correct the deviation and get back on the original course (tack).

 

Does that make sense?

 

Alan

[Balimbras]

Well, I've been out a time or two, and have learned a thing or two. Hoping to get that up to 3 or 4 over the next few days.

 

Yeah, Alan, you set the display type on the navigation page, choose between 'bearing' and 'course'. Bearing is the one most typically used, and the default for the Vista. I thought I was being clever changing it to 'course' without realizing the changes that the Vista assumed in basic nav function.

 

I realized what was happening when I did just that, hit 'goto' again from a new location, and the needle would show, accurately, the current bearing to target, but moving left or right didn't change the heading indicated, the cdi showed distance off track, and the whole display would rotate showing new heading. That last part is the confusing bit, unlike a VOR, the Vista's CDI display rotates to show compass heading, not bearing to target.

 

When I learned to fly, the instrument that I used to operate the VOR navigation system had a display like the Vista's CDI. Behaved the same way, too, although I expected something different from the Vista.

 

Basically, in a CDI, you dial up the course you want, and the centre needle shows how many miles off TRACK you are. This indication increases if you are also off HEADING.

 

I expected the Vista to operate like a VSI (?) or Vertical Situation Indicator, which is the dashboard display some autopilots use. In this gizmo, the needle that the CDI is part of will also rotate to indicate BEARING to target.

 

I'm still a little fuzzy on the exact mechanics of the Vista CDI, but I can report that the Bearing function works like a charm for caching.

 

That's the key, Jeep, when it's set up to display bearing to target (bearing selected in the Navigation window) then you just follow that needle right to the cache. Worked for me 3 times out of 4 so far, going to try #4 again later this week.

 

Cheers!

[Balimbras]

Well, I've been out a time or two, and have learned a thing or two. Hoping to get that up to 3 or 4 over the next few days.

 

Yeah, Alan, you set the display type on the navigation page, choose between 'bearing' and 'course'. Bearing is the one most typically used, and the default for the Vista. I thought I was being clever changing it to 'course' without realizing the changes that the Vista assumed in basic nav function.

 

I realized what was happening when I did just that, hit 'goto' again from a new location, and the needle would show, accurately, the current bearing to target, but moving left or right didn't change the heading indicated, the cdi showed distance off track, and the whole display would rotate showing new heading. That last part is the confusing bit, unlike a VOR, the Vista's CDI display rotates to show compass heading, not bearing to target.

 

When I learned to fly, the instrument that I used to operate the VOR navigation system had a display like the Vista's CDI. Behaved the same way, too, although I expected something different from the Vista.

 

Basically, in a CDI, you dial up the course you want, and the centre needle shows how many miles off TRACK you are. This indication increases if you are also off HEADING.

 

I expected the Vista to operate like a VSI (?) or Vertical Situation Indicator, which is the dashboard display some autopilots use. In this gizmo, the needle that the CDI is part of will also rotate to indicate BEARING to target.

 

I'm still a little fuzzy on the exact mechanics of the Vista CDI, but I can report that the Bearing function works like a charm for caching.

 

That's the key, Jeep, when it's set up to display bearing to target (bearing selected in the Navigation window) then you just follow that needle right to the cache. Worked for me 3 times out of 4 so far, going to try #4 again later this week.

 

Cheers!