Re: Is GPS MPH accurate
 

Good morning all.

My 'Cab Nag' consistently reads around 10% less than the speedometer in my van.
Upon passing the YOUR SPEED IS? Type signs, my Satnav is bang on whatever the sign says.
Howver, once I was out collecting a bike in deepest darkest Derbyshire with a couple of mates, who had bought along their Satnavs, so just for a giggle we had all 3 going at once, & guess what? They all read differently. At 50 mph on my van speedo my satnav read 45, whilst the others read 48 & 51 respectively.

So in short, I would say you can't rely on them to be any more accurate than your speedometer.


Cheers.

Re: Is GPS MPH accurate
 

I suppose it depends on how many satellites are used to locate and track your position, right?

You've opened a can of geek-nerd worms now stewart :lol:

Re: Is GPS MPH accurate
 

OH BLAST! I didn't think of that when I wrote it! I'd better hide before I get smothered in Anoraks!:shock:


Cheers.

Re: Is GPS MPH accurate
 

SatNag`s are not accurate . Best way to get the most accurate reading is to take your glove off , lick the end of your finger and point it upwards whilst riding and have a guess ....... you stand just as much chance of getting it right .

Re: Is GPS MPH accurate
 

At www.mkivsupra.net (who have a thing about speed) the feeling is that a GPS readout is usually more accurate that a speedo reading.

I have two GPS units (one TomTom satnav and one Snooper) and they both read exactly the same, about 10% under my old stock speedo.

Saying that, under acceleration both units are about 1-2 seconds behind what you are doing.

Just my 2p's worth... :)

Re: Is GPS MPH accurate
 

Well its my Iphone ... And i was going 102 MPH (On my private Runway ) on the speedo for about 1 minute but if a speedo over reads by 5-10% and my tracking software is showing max speed of 104.4 MPH that means that my iphone is well over reading.

as some one just said gps does time vs distance so you wouldnt think it would be that much out .

Re: Is GPS MPH accurate
 

The iphone's GPS receiver is never going to be a match for a dedicated satnav

My Zumo550 reads consistently ~5% below the speedo on my ADV and a little more when in the car

Re: Is GPS MPH accurate
 

but look at the delay gps systems have in sending and receiving information, you will never get an accurate system

Re: Is GPS MPH accurate
 

Its based on triangulating from satellites miles ahead. The angles involved are tiny! I think that it wont be as accurate as some people claim it is...

BTW GPS devices dont send info. Can you imagine the antenna you'd need for that?

I dont think the Iphones GPS is GPS, I might be wrong as ive not really researched it but I think its actually something to do with the actual phones reception from different masts.

Re: Is GPS MPH accurate
 

oh ok .

so if my speedo over reads by 5-10% my GPS device is over reading more.