Author Topic: 798 & v6.250 GPS problem (Read 29301 times)

fox_hunter · « **on:** May 18, 2012, 10:07:34 AM »

I've updated at the last firmware my unit, 6.250 and i've a lot of problem on internal GPS.
No accurancy , about 30 ft in best condictions!
So i use my external Garmin gpsmap60cs by N-MEA link.
However since i buyed my 798, i compared the precision with my garmin.... and my Garmin 60cs isn't the last gpsmodel ... but it have
more accurancy then H798
Where can i download the firmware to downgrade my unit?

ITGEEK · « **Reply #1 on:** May 18, 2012, 10:16:44 AM »

These are the updates available on this site for the 798c:

http://forums.sideimagingsoft.com/index.php?action=downloads;cat=7

fox_hunter · « **Reply #2 on:** May 18, 2012, 11:14:19 AM »

Many thankss !!

mako101 · « **Reply #3 on:** August 21, 2012, 03:27:16 PM »

Have a 798 ci si hd, also looking to upgrade software to 6.250, has anyone else had problems with their internal gps after downloading this software, or any other issues?

xSilmarilSx · « **Reply #4 on:** August 22, 2012, 03:03:28 AM »

Internal GPS is crap, almost useless with the 6.250. Never tried older firmware.
At least I have a Garmin 60CSX for the job!

mako101 · « **Reply #5 on:** August 22, 2012, 05:02:58 AM »

xSilmarilSx, how do you think a humminbird 50 channel external antenna and 6.250 software combo would go?

xSilmarilSx · « **Reply #6 on:** August 22, 2012, 12:43:49 PM »

The same poor performance. Because the problem is not with the GPS receiver but the software that controls it.

It lack position/speed filtering. The tracklog is never smooth and the speed keeps jumping around when a Garmin side by side is rock solid. The 4x update rate made it worst..

I used the Garmin to provide the GPS position to the 798, which smooth thing up a good deal, but the tracklog shows a glitch every minute or so. And on the GPS page you see that the unit still want to revert to it's internal receiver even when I told it to use the Garmin.

Some times the internal GPS loose the satellite signal for a couple of second. Even with clear view of the sky on a Kayak when the Garmin show full signal strength.

mako101 · « **Reply #7 on:** August 23, 2012, 05:30:45 AM »

xSilmarilSx, the software that controls the gps receiver, is it in the software updates humminbird provides and is humminbird able to include position and speed filtering in a new version of software that would rectify the problem?

xSilmarilSx · « **Reply #8 on:** August 23, 2012, 12:15:40 PM »

Normally yes, it could be solved by a firmware update.

rnvinc · « **Reply #9 on:** August 23, 2012, 01:43:34 PM »

Quote from: xSilmarilSx on August 22, 2012, 12:43:49 PM

The same poor performance. Because the problem is not with the GPS receiver but the software that controls it.

It lack position/speed filtering. The tracklog is never smooth and the speed keeps jumping around when a Garmin side by side is rock solid. The 4x update rate made it worst..

I used the Garmin to provide the GPS position to the 798, which smooth thing up a good deal, but the tracklog shows a glitch every minute or so. And on the GPS page you see that the unit still want to revert to it's internal receiver even when I told it to use the Garmin.

Some times the internal GPS loose the satellite signal for a couple of second. Even with clear view of the sky on a Kayak when the Garmin show full signal strength.

xSilmarilSx.. Can you elaborate a little (in layman's speak) in how this "position speed filtering" would improve the HB GPS functionality...??

Rickie

xSilmarilSx · « **Reply #10 on:** August 24, 2012, 02:54:03 AM »

In a system that collect various data, it could be speed, temperature, position, you always want a little filtering of the gathered data to single out erroneous values from the median value. The problem is that the faster you want your data (refresh rate) the less filtering you can use. See it like an average of multiple values.

In a temperature sensor (we will take the HB transducer one in exemple), the mass (weight) of the temp probe provide the filtering you want . The speed that the temp change is slow enough to offer a stable readout, yet small enough to provide a precise value after 5 min in the water.

If you check on professional thermo-couples, the smallest and fastest ones are quick to sense the temperature change, but not really stable enough for many applications. They can measure more than 100°C of temp change per second.

In the case of HB GPS, the 4x refresh rate nullify the filtering you have with a standard 1x unit.
In the 1x units, it can take the time to average multiple values to offer a more stable speed, position and bearing. But the software that run the filtering is complex and difficult to master. Speed can also be derived from the GPS signal doppler and/or the change in position. Doppler is way better, more stable and precise. But HB don't seem to use that method.

My 798 GPS wander between 0 and 2 mph when I stand still... But not my Garmins.. even those 15 years old. The speed readout is unusable on the HB...Even at speed. Numbers keep jumping ±2-5 mph from the stable Garmin speed that has been checked with police radar within ± 1 mph.

It's a shame that you can buy 100$ Garmin Etrex, which have a way better GPS behavior that a 1000$+ HB unit.

mako101 · « **Reply #11 on:** August 24, 2012, 05:53:47 AM »

So filtering may be as simple as taking the average of the 4x per second values and displaying it 1x per second on the chart screen?
Would a 1x per second display provide a much better user experience when hovering over a mark or idling very slowly?
What about a scenario where a recording is made at about 3 miles per hour, and the user wants to mark structure accurately, given the boat is moving about 4.4 feet per second, how would accuracy be affected using 1x compared to 4x?

xSilmarilSx · « **Reply #12 on:** August 24, 2012, 12:55:29 PM »

The accuracy of a WAAS GPS receiver is around 15ft.

So when you take your waypoint, you can be 15 ft from the "real" position.
If you come back to your point a couple of hours after, you could also be 15ft from the waypoint that was marked 15 ft off the real position.

So you could be anywhere from 0 to 30 ft from your desired position. But normally you can think of 15 ft of combined error.

And if you mark your position from the sonar reading (structure) you must take into account the cone angle of the transducer that can put you off from 0-10 ft. (or more depending of depth)

I marked an underwater structure with my 798 with multiples passes, using the HB GPS receiver and extracted the position data in HumViewer for each pass. And the precision of the waypoints was around 10-15ft. I had to average 6-8 positions to have a real good idea. But next time, on the lake, the GPS still can put me 0-15ft offset of my calculated position.

And take into account that if you mark structure from the SI image, the position accuracy is worst that if you take it from the 2D sonar. Since the unit can't really know how far the target is on the side of the boat.

rnvinc · « **Reply #13 on:** August 24, 2012, 01:09:18 PM »

Is this similar to what you describe in a filter...??

http://julien.cayzac.name/code/gps/

Rickie

xSilmarilSx · « **Reply #14 on:** August 24, 2012, 05:16:37 PM »

Yes, it's something like that!

rnvinc · « **Reply #15 on:** August 24, 2012, 07:56:34 PM »

Yup... I've already fought that battle with the HB community and lost....

Just like King Leonidas at the battle of Thermopylae fought a brave battle for a noble cause....

He still perished with the 300... Simply because...

There wasn't enough of them to stand against the masses...

Rickie

xSilmarilSx · « **Reply #16 on:** August 24, 2012, 11:39:58 PM »

And that's why I will always have a reliable Garmin receiver for the navigation.

xSilmarilSx · « **Reply #17 on:** August 28, 2012, 02:59:35 AM »

17 post in a tread about GPS problems, and no answers from HB...

Humminbird_Greg · « **Reply #18 on:** August 28, 2012, 10:50:42 AM »

Sorry, I did not know that there was anything posted here that I should answer.

fox_hunter wanted access to older versions of software as he believes the 6.250 software has caused problems with the internal GPS of his unit. Someone gave him the correct area of this web site for this.

mako101 asked if anyone else had problems with the 60250 update.

You are obviously unhappy with the GPS systems that we sell versus another brand.

Rickie is unhappy with a feature used in our units (displaying a red O when the direction of travel cannot be reliably calculated).

Did I miss anything?
What “answers” are you looking for?

rnvinc · « **Reply #19 on:** August 28, 2012, 01:12:17 PM »

See xSimiralXs..

I stand alone with the few slow trollers who actually fish at speeds of 0.1- 0.4mph...

There just isn't enough of us to make an impact against the masses who never use their units that slow..

Such is life sometimes...

I still love my "bird"...
I still despise that "Donut"...

Rickie

ITGEEK · « **Reply #20 on:** August 28, 2012, 01:28:07 PM »

Greg,
I'd be interested to know if Humminbird will make the GPS more accurate
at extremely slow speeds. At least change the doughnut to an arrow when
the boat starts moving.

Are they looking at this problem?

fast talker · « **Reply #21 on:** August 28, 2012, 02:07:39 PM »

I am curious if I am reading this correctly.
Are the Garmin GPS units more accurate than the more expensive Hummingbird GPS units?
I am planning on purchasing the 2013 998 c SI Combo with the LED display screens.

Humminbird_Greg · « **Reply #22 on:** August 28, 2012, 02:35:44 PM »

Quote from: ITGEEK on August 28, 2012, 01:28:07 PM

Greg,
I'd be interested to know if Humminbird will make the GPS more accurate
at extremely slow speeds. At least change the doughnut to an arrow when
the boat starts moving.

Are they looking at this problem?

ITG,
I cannot comment on any future changes to our products: either because I just don’t know or because the information has not been released to the public yet (usually due to the former).

Humminbird_Greg · « **Reply #23 on:** August 28, 2012, 02:45:23 PM »

Quote from: fast talker on August 28, 2012, 02:07:39 PM

I am curious if I am reading this correctly.
Are the Garmin GPS units more accurate than the more expensive Hummingbird GPS units?
I am planning on purchasing the 2013 998 c SI Combo with the LED display screens.

fast talker,
I don’t know what the accuracy of the other brands is. Our tests show that our standard GR50 GPS Receiver has a CEP (50%) rating of 1.5 meters (4.92 feet) and a 95% rating of 4.0 meters (13.12 feet). In other words, 50% of the time you will be within 4.92 feet of your actual position and within 12.12 feet 95% of the time. This testing was performed here in Eufaula, Alabama (U.S.A.) and so the WAAS satellite corrections were being used.

fast talker · « **Reply #24 on:** August 28, 2012, 02:57:08 PM »

That is good enough for me.
By the way..... I did find and purchase the AS WX-1; sure hope it will work in the new units.
Thanks for all the help you have given;
Ted Simons

ITGEEK · « **Reply #25 on:** August 28, 2012, 03:26:02 PM »

fast talker,
The issue is not whether Humminbird units have accurate GPS,
they do.
The issue is that the directional arrow won't start to display until
you are going at .5+ miles per hour.
So, until you reach that speed, you will see a round red doughnut
on the screen.
I don't troll that slow, so it's not an issue with me, but some
Crappie fishermen are pretty upset about it.

Some manufacturer's units will show the boat direction at .1mph.

fast talker · « **Reply #26 on:** August 28, 2012, 06:34:32 PM »

Gotcha......
That's why I ask questions; I like to know and not speculate.
Thanks for the help;
Ted Simons

Bob B · « **Reply #27 on:** August 29, 2012, 06:25:27 PM »

Quote from: ITGEEK on August 28, 2012, 03:26:02 PM

Some manufacturer's units will show the boat direction at .1mph.

I have seen a lot of discussions about this on various forums. On one forum, I saw a post where a guy had a Lowrance unit and a Humminbird unit on his boat. When he was moving at slow speed, the Humminbird would go to the "donut" but the Lowrance would continue to indicate a boat direction.....Only problem was, the boat was not moving in the direction the Lowrance unit indicated....It was actually off by about 90 degrees....So, you could conclude that the Humminbird was actually better in indicating when it couldn't accurately display the direction of movement.
I haven't seen any side by side tests with Garmin.

ITGEEK · « **Reply #28 on:** August 30, 2012, 09:56:22 AM »

That's a very good point Bob.

What good is it to show a directional
arrow, if it is not pointing exactly where
the boat is heading?

It seems that would be very misleading.

This video shows tests with multiple units:


Humminbird Project Donut GPS comparison

mako101 · « **Reply #29 on:** August 30, 2012, 04:08:12 PM »

How would a Humminbird internal antenna unit compare?

Is this the 1x or 4x per second?

What Humminbird antenna is being used?

Is WAAS satellite being used?

sonar2000 · « **Reply #30 on:** August 31, 2012, 06:57:29 AM »

certainly an internal antenna is more susceptable to loss of signal due to blockage. I am not sure how the internal compares to the GR50 in ability to seek and sync on as many satelites..
Chuck

mako101 · « **Reply #31 on:** August 31, 2012, 07:52:51 AM »

Chuck, the 798 with internal antenna has lost gps signal several times, once whilst recording, and at times the arrow points backwards for a few seconds before pointing in the direction of travel. Its mounted with a ram bracket above the gunwale, the only possible obstructions are a bimini top canopy, the outboard and the driver. How do you think a GR50 external antenna mounted one foot above the bimini and directly above the transducer would perform? Can you think of any other way to maximise the performance of the antenna?

sonar2000 · « **Reply #32 on:** August 31, 2012, 04:08:12 PM »

Not to try and sell you anything but you will find the GR50 is much better than an internal. It will work well on the top. GPS accuracy will not be effected all that much in relation to the transducer as the slant angle and the algorhythms used to show a position is somewhat off any way.
If you get the GR50 you could try different places using double sided sticky tape for temporary mounting..
Chuck

mako101 · « **Reply #33 on:** August 31, 2012, 09:18:57 PM »

Chuck, thanks for the straight answers, you cleared away any doubts about the external being that much better. Have been in possession of a new GR50 for some time but wondered how much better they really were. The Australian distributor was out of stock of but was able to order online from the US for half price including freight.

xSilmarilSx · « **Reply #34 on:** September 05, 2012, 03:05:34 AM »

Do you find that speed reading stable?
Taken on my last fishing weekend, no wind, stable trolling speed.


HB 798c HD SI GPS problems

ITGEEK · « **Reply #35 on:** September 05, 2012, 11:53:33 AM »

I read where the human body can block GPS signals.
xSilmarilSx:
In your video, I can first see a shadow on your unit.
Then, I can see the shadow of your head come in.
If you or something else is partly blocking the sun, it may also be
partly blocking GPS sattelites.

Jim Jack · « **Reply #36 on:** September 05, 2012, 12:37:13 PM »

ITG, that is not a body blocking the signal.

There is either a SW or HW issue with his unit.

xSilmarilSx · « **Reply #37 on:** September 05, 2012, 02:12:11 PM »

It's not a blocking issue since I have a Garmin receiver 2 inch at the side that is rock solid.

This is the same exact setup, but with my 778c which is GPS fed by the Garmin.
Same place, same boat, same setup. Just the head unit that is different and the GPS receiver (Garmin vs HB)


Humminbird 778C

Jim Jack · « **Reply #38 on:** September 05, 2012, 02:45:43 PM »

What does the 798 show on the gps diag screen?

ITGEEK · « **Reply #39 on:** September 05, 2012, 02:46:12 PM »

One thing I did notice:
In your first video, the system is updating, I'd say 4 times a second.
In the second video, the system updates much slower, I'd say one
time every 3 seconds.
In the second video, the speed still jumps around, once from 1.5 to 1.8,
then again from 2.0 down to 1.6.

A slower display is going to appear much more accurate than a faster display,
since it displays the same speed longer on the screen.

Whistler · « **Reply #40 on:** September 16, 2012, 08:24:59 PM »

Glad I found this thread.

The big problem I'm having is difficulty in tracking down my way points using my 798. I use the Course Up setting on the 798 when on the trolling motor (obviously moving slowly) while moving to way points I've previously created, the map screen spins quite frequently making it difficult to move to my way points. I assume this is because the unit is having trouble determining the direction I'm traveling in at slow speed.

I don't see this same behavior on my 1198.

mako101 · « **Reply #41 on:** September 17, 2012, 05:00:49 AM »

Chuck, you are right about the GR50 being much better than the internal antenna. Using the internal antenna, the "donut" was moving all over the place as the boat sat motionless in the driveway, but with the external mounted above everything in the boat, the "donut" was motionless and the gps diagnostic screen showed estimated position error of 1.0 meters and dop of 0.96. Yet to do a water test but so far the external does seem that much better. Thanks for the advice.

bobxxx · « **Reply #42 on:** October 10, 2012, 12:21:34 AM »

I have also had trouble since i put in the 6.25 update.I wasn't sure because i was also trying to fish.I understand the gr50 giving a more reliable reading,but how do we explain a different gps giving so called reliable positions? I hate to start messing around with different update versions.Can someone fairly knowledgable,tell me if a should back my unit up to previous version.I am giong to get the external antenna.
Thanks,Bob

sonar2000 · « **Reply #43 on:** October 15, 2012, 04:28:12 PM »

Bob, a downlevel is fine as long as you dont go so far back that the code is not compatable due to internal component changes in the hardware.
Three things to remember when changing code.
1..Only one code level appropiate for your unit on a card.
2. Have a backup of current code on a separate card.
3. Follow code install procedures to the letter.

Chuck

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