Nav or Speedo? What do you believe when setting your Speed?

[Betty]

All this GPS talk has me wondering if it is worth having one for the bike (don't have one in the car either) for the (very) occasional road trip.

What are your opinions (yes I know its slightly off topic and has been discussed a little in the past) ... but what are your opinions on their value?

Is it worth the approx. $700+ for a bike specific GPS (road trip generally means it will get wet), etc, etc?

BTW I have just bought a hardcopy GPS, obviously it doesn't have the same level of detail as one of those digital ones but that's why I was wondering is it worth the extra fundage?

[Yellow Meanie]

Hi everyone, I've been away for a while, but I'm back 

As a mariner I'm supposedly trained in the proper use of GPS...

Suzyj, you are quite right in saying that there is no more "selective availability". Thankfully the Yanks switched it off, and I have heard rumors that it would actually be illegal for them to switch it on again.

Bazz, I think the unit you are talking about in the police boat would be a Differential Global Positioning System (DGPS).
It is basically a GPS which also receives signals from ground based stations. It is much more accurate than a normal GPS and is also available for civilian use, but much more expensive. We use these on our ships.



Here's some of the more common errors in normal GPS:

Satellite geometry: When the position of 3 or more satellites provides a bad "angle of cut" for determining a position. Similar to getting a "cocked hat" in coastal navigation.

Multipath effect: When the radio signal bounces off another object before being received by the GPS. Eg, buildings, trees etc...

Atmospheric effects: As the radio signal from the satellite passes through the atmosphere it passes through layers of different density (Ionosphere, Troposphere...) The signal can be refracted, like light through water, causing it to be slowed down, causing an error.

There are actually a lot more errors that are way too technical for me to explain, especially without boring the hell out of everyone. But they really are insignificant anyway.



Any normal GPS will be extremely accurate in giving you a speed, as long as it is receiving a good signal.
Please bear in mind that the signals do drop out occasionally, as has happened to me while navigating up and down the coast.

I would do a few comparisons between your speedo and GPS, so you know what is what. Then read your current speed of the speedo, as it is actually ground referenced, then calculate your actual speed in your head.



Betty - what is a hardcopy GPS? You mean topographic map? 

[CairnsDuc]

Interesting Reading Yellow Meanie, That's one thing I like about this website, put up a topic and get some excellent information 

All this GPS talk has me wondering if it is worth having one for the bike (don't have one in the car either) for the (very) occasional road trip.

What are your opinions (yes I know its slightly off topic and has been discussed a little in the past) ... but what are your opinions on their value?

Is it worth the approx. $700+ for a bike specific GPS (road trip generally means it will get wet), etc, etc?

BTW I have just bought a hardcopy GPS, obviously it doesn't have the same level of detail as one of those digital ones but that's why I was wondering is it worth the extra fundage?

The motorbike units are quite expensive, and most of the ones we have at work such as the Rider from TomTom, and the Zumo from Garmin are very good quality, just
in desperate need of an upgrade or replacement with new models. I have a couple of Customers with the Zumo from Garmin and they do like them. and they can also
be used in a car, saves needing one for both the car and the bike.

Around a town you are familiar with I don't think you would get value from them, but in my case (For example) with my move from Cairns to Launceston, I have to travel
over 4000k's and then learn my way around a new Hometown. And because I am traveling Solo the whole way, I wouldn't want to keep pulling over to check maps or get
directions, Just program in the address, press go and as a customer put it the other day, let the "pregnant dog in the Box" tell you were to go.

Before I got the TomTom's (A 5" XXL540 and a 3.5" Tom Start) and I needed to find an address in Cairns I would check it on Google maps. but that won't be very practical
when I move to Tasmania with so many new addresses and places to find.

I see a number of GPS/Nav units come in not working because people throw them in the cupboard and forget about them for 6 - 12 months, the battery shits itself and the unit
won't work. like most electronics they don't like not being used.

[Betty]

Betty - what is a hardcopy GPS? You mean topographic map? 

Motorcycle Atlas ... hardcore old-school. Nothing as complicated as a topo map.

snipped for brevity

Thanks CairnsMan (hey what are we gonna call you next month?)

It was the big trips to unfamiliar places that I was concerned about. Seems I  might go old school for now ... I'm not seeing too many convincing arguments for spending big dollars on something that needs an update.

[bikeless]

Hi everyone, I've been away for a while, but I'm back 

As a mariner I'm supposedly trained in the proper use of GPS...

Suzyj, you are quite right in saying that there is no more "selective availability". Thankfully the Yanks switched it off, and I have heard rumors that it would actually be illegal for them to switch it on again.

Bazz, I think the unit you are talking about in the police boat would be a Differential Global Positioning System (DGPS).
It is basically a GPS which also receives signals from ground based stations. It is much more accurate than a normal GPS and is also available for civilian use, but much more expensive. We use these on our ships.



Here's some of the more common errors in normal GPS:

Satellite geometry: When the position of 3 or more satellites provides a bad "angle of cut" for determining a position. Similar to getting a "cocked hat" in coastal navigation.

Multipath effect: When the radio signal bounces off another object before being received by the GPS. Eg, buildings, trees etc...

Atmospheric effects: As the radio signal from the satellite passes through the atmosphere it passes through layers of different density (Ionosphere, Troposphere...) The signal can be refracted, like light through water, causing it to be slowed down, causing an error.

There are actually a lot more errors that are way too technical for me to explain, especially without boring the hell out of everyone. But they really are insignificant anyway.



Any normal GPS will be extremely accurate in giving you a speed, as long as it is receiving a good signal.
Please bear in mind that the signals do drop out occasionally, as has happened to me while navigating up and down the coast.

I would do a few comparisons between your speedo and GPS, so you know what is what. Then read your current speed of the speedo, as it is actually ground referenced, then calculate your actual speed in your head.



Betty - what is a hardcopy GPS? You mean topographic map? 

yes dave you are right but what it does say is how far the gps is out and the radar which is hooked into the system comfirms this and the gps is never spot on all the time hence too say that a stand alone gps is more accurate than a speedo is wrong ,the speedo might be out by x amount but it never changes  but it will tell you your speed over ground and that is what i said so it will show you the difference between you vehicle speedo and the gps speed but it also takes time too do this and depending on the clock speed of the gps engine ive found with of the shelf units too the commercial units dont show the same speeds and locations i know its been a while since i was at marine time college but i still see alot of units and help fit them not as big as the units you work with dave and too say theres no varible any more i have had notification gps shut downs twice since 2000   

[CairnsDuc]

Gee Betty I never thought about the Name thing, CairnsDuc won't be suitable anymore, might have to switch back to
my regular Forum name of SpankyMK.

Saw an interesting solution from a motorbike riding customer yesterday, he bought a TomStart off me a few weeks back.
He wanted a motorbike Nav, but it was way out of his price range. So he said he would take this unit and fiddle about
with it to see if he could set it up on his bike, I said if he did would he mind calling in so I see his setup.
I thought it might be a bit rough or Dodgy (Bush mechanic kind of thing) but no, good little setup he had made.

This Nav was only $160 to buy, with the latest map, and he took it away and made a small bracket of his handle bars,
bought a box of Sandwich bags and proceeded to make himself a waterproof Nav.

He made a small alloy bracket to which he attached the suction cap, with a couple of zip ties for safety.
(He had a BMW, didn't even think to look at the model, dual purpose, single cylinder model with small
windscreen fairing)

He made a small cut in the bag to feed the bracket through that the Nav clipped to.

The Bag stayed attached to the Nav bracket with a Zip tie, through the Zip lock bag (Which was facing down)
He would put in the Nav with it's power cable and then seal up the zip lock.

Eureka! Bike Nav!

Now as he pointed out he could not hear the voice direction, but like any Nav they will always tell you
what turn and which direction is coming up on the screen, and of course the Nav counts down the distance
to the turn anyway. But he rides around all over north Queensland as a relief Ambulance officer (He covers
for people who are off sick or on Holidays) so he may get a phonecall at any time of the day or night directing
him to any of the Ambulance offices/depot's in the greater region. And with Ambos taking home Ambulances
in the regional areas at night he may have to go to someone's home to collect the Ambulance.

Nice bloke, really switched on guy, but I could only imagine some of the Horrors this guy has seen in his
20+ years as an Ambo.

I am kicking myself I didn't get any pictures of the setup , simple little solution and saved himself about $600!

[Betty]

I've heard of the ziplock bag solution before, the problems I envisaged:

. I am incompetent (read: it sounds too complicated for me)
. I can't imagine it is fool proof (read: I am a fool)
. I imagine it would be pretty messy when you pull up at pub for lunch, etc and want to pop it off

Does seem to be a solution people are adopting though ... apparently too small of a market to get the manufacturers pulling their collective fingers out.

[suzyj]

I just use my phone as a gps.  I don't mount it to the bike though - I just keep it stowed in a pocket.  If I'm lost, I stop, pull it out and have a look at where I am using google maps.

I do the same if I'm travelling in the car, too.

I'd be a little leery of a gps mounted on my bike, to be honest.  Unlike in a car where they're not far from your eyesight, with a bike you've got to look right down at it, and then trying to decipher the road names and stuff could mean you're eyes are off the road for a long time.

[CairnsDuc]

Well this one was just below his instruments, so his eye sight only dropped down a little bit below what he normally looked at
anyway.

And removing it is easy, open the bag, unclip it from it's bracket and unplug it's power cable, less then 5 seconds work, and the
Start model is tiny, so it fits easily into a pocket.

He put it back on the bike while I was standing there, Clip it back on it's mount, plug in it's power plug, zip up the bag.
probably less than 10 seconds to do, he switches it on and programs it while waiting for the bike to warm up, pops on
his gloves and off he goes. And he can program it through the bag.

Torn Bag? (That's gotta hurt!) no worries, he carries some spares and some Zip ties in his back pack, 2 mins work and he's back
on the road again.

Simple setup, but very effective!