Model: | ALL SI Models |
Suggested Upgrade: | Calculate GPS direction when not moving |
Explanation: | Use two or more units with separate GPS pucks to determine the direction of the boat when not moving. We can fish structure without marker buoys. |
Added in Software Version: | |
Comments on Update: |
Atmospheric disturbance will change the signal to what we have today in term of accuracy.
WAAS is used to offset the atmospheric disturbance but you will never have centimeter accuracy without using a DPGS setup which will cost you more than your boat to setup.
My brother have used sub-meter precision GPS from before year 2000. But you can only have that amount of precision with post-process, not in real-time in the unit.
The old accuracy was ±300 feets..
Since I have some experience from GPS technique I must chime in and tell that position, direction and speed are calculated from a blend of doppler shift and position data with help of statistical and Kalman filtering methods in all GPS units and not from successive positions only. These methods can be tuned in many ways by the GPS engine manufacturer and the navigation software programmer. It's not that easy to tell what HB should do about any issues with direction at low speed since it's not known how stuck they are in the hardware/software preconditions. But I know that correct speed and direction can be estimated very accurately from only the doppler shift in the satellite signals, much more accurate than what's possible from the GPS positions.
Rickard
Exactly... the doppler shift and the filtering method are very important in GPS usability... Something HB should check more thoroughly with their wandering position and inaccurate speed display.
Moose1am, What you are saying about GPS accuracy is absolutely correct....if the accuracy could be improved, the unit could show direction at a Lower speed utilizing GPS only.
I think your Garmin is not utilizing the electronic compass for your map orientation even though the unit has a compass. With a handheld unit this would be very hard to do because you could have the unit pointed in various directions relative to your movement, or even in your pocket.
With a fixed mount unit, the software could utilize the electronic compass when it was unable to get a good GPS heading. It would be able to determine the direction the unit is pointed relative to the boat when getting a good GPS heading and "calibrate" the compass.....hope this makes sense to somebody besides me.