Fluctuating M.p.h. On 997

I was out today and i checked the speed with a handheld gps the hand held was a constant 0.7 I was on a steady drift. THE 997 showed between .6 and2.9 but real quick jumps it would be .6 then 1.3 then .9 then 2.3 within seconds apart. The boat wasnt changing speed. The handheld was real steady it would maybe vary a tenth or two at the most. I have my puck mounted on the backside of the 997 facing up with the extra wire wraped around it. It is basicly like the ram mounts that cabelas sells.

I know one of you electronic wizards can help me. Thanks wilbur

Try it without the extra wire wrapped around it. You may be getting interference from it.

I tried hooking it up in the house it was sitting on the table and the M.P.H. was reading and still fluctuating. GPS puck was dead still.

The unit isn't leaning back over the puck any is it? The puck needs to be 100% unobstructed view straight up. I have the same basic set up and if I tilt my unit back just a hair to far it will be slightly over the puck and causes the same issue your having.

If you guys are using the mount that places the GPS Receiver behind and below the top of the unit than you are depriving it of the signals from any satellite that may be in the direction of the unit. The unit is probably blocking some of the signals that couple help further define your position – thus improving accuracy and lessening the speed jumping around. For best results you should have the GPS Receiver mounted so it has an unobstructed 360 degree view of the sky from a 10 degree to horizontal angle up. For the mounts like it sounds you are using see if you can fashion some type of riser to place the GPS Receiver just about the height of the unit and let us know if that helps with the low speed readings.

Greg Walters at Humminbird

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Originally Posted by Humminbird_Greg

If you guys are using the mount that places the GPS Receiver behind and below the top of the unit than you are depriving it of the signals from any satellite that may be in the direction of the unit. The unit is probably blocking some of the signals that couple help further define your position – thus improving accuracy and lessening the speed jumping around. For best results you should have the GPS Receiver mounted so it has an unobstructed 360 degree view of the sky from a 10 degree to horizontal angle up. For the mounts like it sounds you are using see if you can fashion some type of riser to place the GPS Receiver just about the height of the unit and let us know if that helps with the low speed readings.

Greg Walters at Humminbird

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That style mount is bad news cause every time u turn boat just alittle you block existing signals, best thing to do with that style mount plate is to use it for a anchor on one of your marker buoys;)

I dont think theres a thing you CAN do with it. The GPS on these Humminbirds leave a LOT to be desired. I LOVE my unit and I wouldnt trade it for ANYTHING...except one with a faster more accurate GPS. Its not an issue until you are going SLOW or trying to pinpoint a pile or something.

I can turn mine on in the boat in the yard and it will jump all over the place and tell me I am going 2mph then 1.7, then .9. I have a 798SI with internal GPS and thought about getting the external one. But I see more and more guys having the same issues with their $200 external antennas too. :confused:

Tighten up humminbird!!

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Originally Posted by Kman

I dont think theres a thing you CAN do with it. The GPS on these Humminbirds leave a LOT to be desired. I LOVE my unit and I wouldnt trade it for ANYTHING...except one with a faster more accurate GPS. Its not an issue until you are going SLOW or trying to pinpoint a pile or something.

I can turn mine on in the boat in the yard and it will jump all over the place and tell me I am going 2mph then 1.7, then .9. I have a 798SI with internal GPS and thought about getting the external one. But I see more and more guys having the same issues with their $200 external antennas too. :confused:

Tighten up humminbird!!

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I think I read at the HB forums that some of this may be due to the fact that the signals are being read from satellites that are moving. Can't say if that's a fact or not.

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Originally Posted by yankee doodler

I think I read at the HB forums that some of this may be due to the fact that the signals are being read from satellites that are moving. Can't say if that's a fact or not.

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Yep they really moving on, all 30 (24 active and 6 standby) of them. Bout 8700 miles per hour and circle the earth twice a day at an altitude of 12,000 miles. However they know where that are located in space within a nano fart. Thanks to the military and the atomic clock.

The two WAAS satellites are geostationary. One is on east coast and one on the west cost just above the equator.

My favoite subject. Kinda.:)

Satellites moving ain't the problem....Military would be in a hellova mess if movement was a problem....

When you sitting still, the gps just wants you to move. It just gets figity and wanting you to do something. Kinda like a snotty nose kid wanting attention.