Thread: Humminbird GPS In-Depth...

I always thought the dark gray bars were the only sat's that helped us? Sort of like HD TV its working or not does not matter that your TV shows that Channel so and so is there if the signal is not strong its not any good to it. Is this not the same with the GPS?
I know when I have a bunch showing but say only 5 or so locked down its working good and does not matter now many others it can show that's not locked down or solid gray..
Pete

Pete,
The satellites shown in dark gray/Black are the ones that the GPS Receiver is currently using. These are the ones that it has determined will give it the best accuracy due to the signal strength, health of the satellite and mostly due to its position in the sky. The light gray ones may have a strong enough signal but are not being used as the GPS Receiver has determined that it would be less accurate if it used the information from these (or it received data from the GPS system to not use those satellites).

This is one of the cases where more is better, however the gain in accuracy will is not linear (Example: the EPE is 10 feet with four satellites. It would not be 5 feet with eight satellites).

Originally Posted by Humminbird_Greg

Pete,
The satellites shown in dark gray/Black are the ones that the GPS Receiver is currently using. These are the ones that it has determined will give it the best accuracy due to the signal strength, health of the satellite and mostly due to its position in the sky. The light gray ones may have a strong enough signal but are not being used as the GPS Receiver has determined that it would be less accurate if it used the information from these (or it received data from the GPS system to not use those satellites).

This is one of the cases where more is better, however the gain in accuracy will is not linear (Example: the EPE is 10 feet with four satellites. It would not be 5 feet with eight satellites).

Are you saying that Garmin is wrong?

I'm not saying anything about any other company Cane Pole. This is the information that I was told by one of our Engineers and have seen it in print on the internet as well.

Originally Posted by Cane Pole

Dear Tom,


Thank you for contacting Garmin Marine Support.


There is no advantage to having more satellites, all that is needed is 4 satellites to connect to get 3-D GPS tracking.


Thank you for contacting Garmin and have a nice weekend.


Sincerely,


James Frazier

The statement says all that is needed.... Not that you can only connect to 4 satellites at one time. The more satellites you connect to the better. Our company's sub-centimeter survey grade GPS systems will connect to many many satellites in the field. The more the better for corrections. I am sure you can be tracted with 4 and only four is need to be tracked... but the more you have the better the accuracy.

DoubleG

Originally Posted by DoubleGobble00

The statement says all that is needed.... Not that you can only connect to 4 satellites at one time. The more satellites you connect to the better. Our company's sub-centimeter survey grade GPS systems will connect to many many satellites in the field. The more the better for corrections. I am sure you can be tracted with 4 and only four is need to be tracked... but the more you have the better the accuracy.

DoubleG

But he (Garmin man) also stated there is no advantage to having more satellites. I specifically ask about the HB unit since I have one. Gregg also stated 8 satellites would not improve the accuracy much by his analogy. So when we go get a new gps, who do we believe and what do we get? I am a skeptic when it comes to believing what is internet and manufacturers claims (all of em). That is why my name is Thomas.

I think the advantage of tracking more than 4 satellites would be that you have a better chance of keeping contact with at least 4. For instance on cloudy, rainy days or when you might encounter obstacles which would obstruct the signal from one or more satellites. Three for triangulation to get lat and long. One more for altitude. Five or six more for when 1-4 might become unavailable for whatever reason.

I believe the confusion of tracking vs triangulation is getting crossed over. You can track all you want, but triangulation from 8 produces not much better resolution than triangulation from four.