Etrex Vista - Moving Average Speed

[pdhbo]

Can someone tell me how this is calculated. The manual seems to be quiet on the subject. Is there any way I can change the period of the moving average calculation??

[+mrp]

It's the average speed for the entire time you have been moving since resetting the trip odometer. I'm guessing that it defines moving as "having moved more than some small distance since the last measurement". My legend seems to do a reasonable job, and I'm sure that the software is the same on the vista.

 

-- Mitch

[pdhbo]

quote:

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Originally posted by Pneumatic:

It's the average speed for the entire time you have been moving since resetting the trip odometer. I'm guessing that it defines moving as "having moved more than some small distance since the last measurement". My legend seems to do a reasonable job, and I'm sure that the software is the same on the vista.

 

-- Mitch

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The vista also gives me overall average speed which according to my observations is the correct average speed since last trip reset. Is the difference between the two the fact that the one uses overall trip time and the other only moving time (ie it ignores stopped time?)

[argyle]

So for ETA does the software use the Average (moving) or the Overall average to give you the ETA?

[pdhbo]

It is my understanding that ETA is calculated using VMG and Current distance but I am new at this so I may be wrong

[pdhbo]

It is my understanding that ETA is calculated using VMG and Current distance but I am new at this so I may be wrong

[+mrp]

QUOTE]Originally posted by pdhbo:

Is the difference between the two the fact that the one uses overall trip time and the other only moving time (ie it ignores stopped time?)

 

That's my understanding. Again, exactly how it determines when you're stopped and when you're moving (since you're position ususally jumps around a little bit just because of error) is a bit of an algorithmic black box.

 

As for how it comes up with ETA and ETE, I don't think it's strickly VMG and distance, since VMG is often briely negative, and that doesn't seem to faze the estimate. I'm guessing that garmin uses some sort of sliding window average of VMG, say over 15 minutes.

 

-- Mitch

[+apersson850]

As far as I've found out, when the Vista says that your speed is zero, it stops updating the average moving speed. You can easily tell, if you look at the time moving and the time stopped at the same time (!). As soon as your speed becomes zero, the stopping time will start counting.

 

It seems that ETA is calculated with the latest sustained speed. It can't be a 15 minutes average, since it will react a lot quicker than that, if you change from walking to driving, for example. But how they do when it does calculate an ETA, in spite of the fact that you are moving away from the destination, would be interesting to know.

 

Anders