Humminbird Side Imaging Forums
Side Imaging Forums => 798c SI => Topic started by: gofission on April 26, 2011, 06:14:26 AM
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So i'm heading south at 5 knots looking at the chart view and the boat icon is pointing straight up and says 000 for a heading. (north up option selected) plotter is drawing a track line south correctly, so the gps knows that I am traveling south. Then I notice that it flips back and forth between 000 and the actual heading. It appears to use 000 as a default heading if heading data is missing for some reason. The playback on HumViewer also shows the same. Confusing and annoying. In my experience its better to have no data than bad data. Software glitch or hardware?
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Looking back at the videos I shot last weekend, the heading number is used to compute the Lat/Lon of the waypoint generated when using the cursor either on the unit or during playback with HumViewer. Which in turn makes every WP marked with the heading at the false 000 degrees invalid. :(
Is anyone else having this 000 heading problem?
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Checked today and 10 satellites in view. EPE 11 feet. Heading showing 000 most of the time now at any speed less than 8 knots. Anyway, the side scan is working great in saltwater! I will have to do my searches south to north for cursor driven waypoints to even be close to accurate until I have time to send this back for repair.
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Latest software update seemed to help. Heading still freezes at last known heading going <2 knots But i'm not going to worry about it.
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dont give up. This should not be happening...
As long as you have +.5 knots it should not do this..
Dont know the cause but lets see what happens...
Have we determined that the gps puck is not getting blocked for some reason..?
Chuck
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I have the internal gps antenna. I checked the satellite status view and i had at least 8 in view and receiving. The track is plotting perfectly smooth and the heading now works when moving +2 knots. Flat calm water. It least its better than 000. I use north up display. If the gps can plot the track accurately, it should be able to compute the heading. FWIW, with my boat tied to the dock and chart zoomed in all the way, the boat position is moving over an area of about half the screen at speeds up to 3 knots. In contrast, my Garmin 540 shows between 0 and 0.1 knots and movement of 1/2 boatlength, but it has an external antenna clear of everything. I will post a photo of both units displays tonight.
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Added pics. Boat is tied to dock. To enter and leave the dock, I go west about 30 ft and turn south and go out to the creek. Notice the HB position is more active. Both units track lines are for the same approximate period. The garmin has at least one more trip in and out of the dock because the HB was not on the boat yesterday.
012 magnetic = 000 true
[attachment=2][attachment=1]
Garmin 540 on same zoom level.
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[attachment=4]
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When the gps is sitting still it will wander around a bit.
I am not sure the internal antennas are as sensitive as the external puck especially when at a standstill or crawl.
Wondering is this could be an antenna problem..
Chuck
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As am wondering that as well Chuck but I am also wondering about your previous question about the internal GPS being blocked too.
Is an HDOP of 1.14 or Estimated Position Error of 26 feet normal for anyone else around the New Jersey area? That is why there is so much position jumping.
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A few updates:
1) The heading indicator does not change until speed is >4.5 knots or about 5.0 mph consistently. This is with the latest software update. This is annoying especially doing sidescan videos. Running at speeds to make the heading work correctly destroys the definition of the images.
2) I temporarily moved the unit out away from everything out on the clear deck. Th HDOP aand Est position error are essentially unchanged.
3) I still cant get the waypoints created with Humviewr on a SD chip to load back into the 798. There is no "upload waypoints" menu choice.