Humminbird Side Imaging Forums

Side Imaging Forums => Helix Series Units => Topic started by: gmoney on September 26, 2017, 02:57:31 PM

Title: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on September 26, 2017, 02:57:31 PM
I'm having a couple issues with my Helix 9 and was wondering if anyone had suggestions. My SI image slowly gets darker as I go deeper and once I'm in 30 feet of water it is completely black.

My other issue is the unit losing its GPS fix. I like having the unit in course up mode and it randomly seems to lose which way is which and I have to shut if off and turn it back on to fix the problem.

Any ideas??
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: rnvinc on September 26, 2017, 07:00:43 PM
It is normal for the imaging to get progressively darker as depth increases because the sound pulse has farther to travel while attenuating (absorbing into the water)  ...

It is common to need to adjust imaging Sensitivity as water gets deeper (and as bottom composition gets softer)  ... to offset these effects of less of the sound pulse being reflected back to the transducer  ...

There are times I have SI Sensitivity maxed out at 20 in only 10ft of water over a mud bottom - and the image is still not as bright as I would like it  ...

It is helpful to have the "SI Enhance" Menu open on the SI view so that Sensitivity can easily (and frequently) be adjusted for changing water depths and bottom compositions  ...
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Does the GPS issue seem to only happen at very slow speeds or is it more random  ...??

Rickie
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on September 27, 2017, 06:45:34 AM
I've had to turn my sensitivity down and surface clutter up in order to prevent erratic depth reading, but I'll try the adjustments you suggested. The GPS think is random, it happens going slow and fast. I have a heading sensor connected for the autopilot and read that I should have the NMEA output turned on so I did that the other day thinking it would fix the problem but it didn't. Very frustrating.
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: rnvinc on September 27, 2017, 06:57:35 PM
When the GPS issue is acting up - are the Chart Views still available or do the Chart Views disappear  ...??

Rickie
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on September 28, 2017, 06:36:02 AM
Yes they are available.
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: rnvinc on September 28, 2017, 06:46:51 PM
Yes they are available.

Can you describe more about the GPS issue  ...??

Chart spinning? Boat icon disappearing? Boat icon scooting sideways? Boat icon on land?

Rickie
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on September 29, 2017, 06:24:32 AM
When I'm going slow the chart will flip back and forth but when I'm going faster and have it set on course up it will flip over and stay that way so the boat icon will be going the opposite way it should be going. The icon that shows North will also be pointing in the wrong direction.
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: rnvinc on September 29, 2017, 07:25:08 PM
When I'm going slow the chart will flip back and forth but when I'm going faster and have it set on course up it will flip over and stay that way so the boat icon will be going the opposite way it should be going. The icon that shows North will also be pointing in the wrong direction.

The issue you describe is a "Normal" occurrence in HB GPS below 0.6mph (when Chart Orientation is set to "Course Up")  ...

The HB Chart Orientation being drawn on the Chart view Defaults to North Up anytime the unit cannot calculate "Course" regardless of the "Chart Orientation" menu selection  ...  (remember Course is the direction the vessel is moving)  ...

"Course" is a calculation (in the HB unit) between successive GPS data samples (taken from the satellites) to determine if the vessel (on the Earth) has moved from the previous GPS data sample (received by the GPS antenna) to the next successive GPS data sample (received by the GPS antenna)  ...

Example  ...: GPS data sample 1 has a latitude/longitude of "N xx W xx"  ... The very next GPS data sample has a different latitude/longitude showing the vessel has moved "X" number of feet from the position of GPS data sample 1 = and thus calculates the vessel has moved in that direction (and plots onto the Chart view the boat icon as "Course moving in that calculated direction)  ...

Due to the inaccuracy of the the GPS system (spec-ed at 8-10meters 95% of the time) - when the vessel doesn't move far enough in a certain amount of time (think less than 0.6mph) = the HB unit cannot calculate "Course"  ... resulting in the unit re-drawing the boat icon (boat icon indicating Course can be calculated) into a circle (circle indicating Course cannot be calculated)  ...

If the HB Chart Orientation setting is set to "Course Up" - and the vessel is moving fast enough = "Course" can continually be calculated from the successive GPS data samples - and the unit keeps the the Chart Orientation drawn on the display as the user selected Course Up  ... meaning "Course (the direction the vessel is moving) is at the top of the screen ...

When the vessel slows down (think less than 0.6mph again) - and the unit cannot calculate Course = the unit Defaults the map orientation on the display to "Default North Up"  ...

Thus = every time the vessel slows below 0.6mph > Chart Orientation drawn on the Chart view Defaults to North Up  ...

And every time the vessel speed up past 0.6mph > Chart Orientation drawn on the Chart view reverts to the user selected setting of "Course Up"  ...
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Setting the HB Chart Orientation selection to "North Up" keeps the map drawn as "North at the top of the screen" - regardless if Course can be calculated or not  ...

The boat icon still changes to a circle at below 0.6mph (meaning Course cannot be calculated) = but the Chart no longer will spin with the Chart Orientation selection set at "North Up"  ...

Rickie


Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on October 02, 2017, 06:58:46 AM
That explains the flipping when I'm going slow but when I'm going faster it will flip over and stay that way so the boat icon will be going the opposite way it should be going. The icon that shows North will also be pointing in the wrong direction.
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: rnvinc on October 02, 2017, 06:46:23 PM
That explains the flipping when I'm going slow but when I'm going faster it will flip over and stay that way so the boat icon will be going the opposite way it should be going. The icon that shows North will also be pointing in the wrong direction.

Try clear Current Track  ... There have been reports in the past where a full Track point cache causes weird charting issues  ...

Note : Track points (20,000 capable) are what creates the trail behind the boat  ...

Rickie
Title: Re: Helix 9 MEGA DI GN2 Losing SI Image in 30+ FOW
Post by: gmoney on October 03, 2017, 06:26:46 AM
I'll give that a try, thank you.
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