Using a satnav on the train

Peter James wrote:

> Heated widscreens are said to be sat-nav unfriendly.

If you have a device with a SiRFstar III chipset GPS receiver, you'll
find it works anywhere (well, maybe not on a Bendyleano). They're super
sensitive and can work well indoors, which was unheard of a few years
ago.

Some SatNav systems always try to lock to a road - so as you pass
roads, bridges, it will jump around all over the place (and, as you
might imagine, keep wanting to recalculate).

Few, if any, have a train mode - so I wouldn't use the navigation mode.
I've tried a few and just left them in the mode that shows your
location and speed (it's always interesting to see how slow most trains
go - like 55-60mph on a train capable of doing 100mph).

Two main map suppliers may also vary their accuracy of railway lines.
Navteq seem to be quite good, but I am not sure about TeleAtlas.

Jonathan
(What Mobile magazine)

> One of the addtional problems is that you've only got a small window to get
> a signal - you can't go up due to the roof and very often the sideways
> outward signals are blocked by dense tree growth or cuttings. Best signal I
> got was on an excursion where it had older stock with the small window
> ventilators, I stuck my (magnetic) antennea on the fascia above the window.
> Worked a treat.
>
> With newer carriages presumably it's not beyond the realms of science to
> have them fitted with a small monitor screen linked to a gps on the roof so
> you can see where you are, like what you get on planes (although obviously
> not 1 per seat!).

Doubt they'd want to show the speed though!

Bill wrote:

> > One of the addtional problems is that you've only got a small window to get
> > a signal - you can't go up due to the roof and very often the sideways
> > outward signals are blocked by dense tree growth or cuttings. Best signal I
> > got was on an excursion where it had older stock with the small window
> > ventilators, I stuck my (magnetic) antennea on the fascia above the window.
> > Worked a treat.
> >
> > With newer carriages presumably it's not beyond the realms of science to
> > have them fitted with a small monitor screen linked to a gps on the roof so
> > you can see where you are, like what you get on planes (although obviously
> > not 1 per seat!).
>
> Doubt they'd want to show the speed though!

I remember taking a handheld GPS unit onto a late night GNER 225
service from KX to Newcastle about 3 or 4 years ago. The speed peaked
at 137mph at one point between Darlington and York...

How accurate 'is' the speed given on a satnav?

They seem to give a diferrent reading to the car speedo.

Which is the most accurate?

In message <MsVRg.33385$cx.31126@newsfe1-gui.ntli.net>, at 18:45:00 on
Mon, 25 Sep 2006, Jim <jimhayes@ntlworld.com> remarked:
>How accurate 'is' the speed given on a satnav?
>
>They seem to give a diferrent reading to the car speedo.
>
>Which is the most accurate?

Satnav should be within 0.1mph. The car speedo something like +10%/-0%
--
Roland Perry

"Jerry A" <jerry.alderson@virgin.net> wrote in message
> Has anyone ever tried hooking up a GPS to a laptop? I'd be interested
> ot know how the comptuer can grab the information and do something
> useful with it.

Before "Tom Tom" came and went, I used a Garmin XL12 connected to my Laptop
using Autoroute 2001 and 3 for directions when I was a Courier. It worked
well for me!

--
Ken Ward

"Society for the production of Maritime Reefs using MerseyRail 142's"
(For membership email... mersey142.splash@ntlworld.com)
"Leave the Mobile Phone at home day Oct 25th 2006"

"Jim" <jimhayes@ntlworld.com> wrote in message
news:MsVRg.33385$cx.31126@newsfe1-gui.ntli.net
> How accurate 'is' the speed given on a satnav?
>
> They seem to give a diferrent reading to the car speedo.
>
> Which is the most accurate?

I've used a Garmin GPS on planes, and find that the speeds it shows are
identical to those produced by the plane's own displays (unlike in the
car, which overestimates the speeds). But the altitude sometimes differs
from the plane's display. I've also found that at sea level, when I know
I'm above the waves, it sometimes claims to be underwater.

So, I conclude that speeds are very accurate, but positions may be a few
feet out.

"Nigel Pendse" <nigelp@clara.co.uk> wrote in message
news:1159219093.10981.0@proxy01.news.clara.net...
> "Jim" <jimhayes@ntlworld.com> wrote in message
> news:MsVRg.33385$cx.31126@newsfe1-gui.ntli.net
>> How accurate 'is' the speed given on a satnav?
>>
>> They seem to give a diferrent reading to the car speedo.
>>
>> Which is the most accurate?
>
> I've used a Garmin GPS on planes, and find that the speeds it shows are
> identical to those produced by the plane's own displays (unlike in the
> car, which overestimates the speeds). But the altitude sometimes differs
> from the plane's display. I've also found that at sea level, when I know
> I'm above the waves, it sometimes claims to be underwater.
>
> So, I conclude that speeds are very accurate, but positions may be a few
> feet out.

I found the position "on the ground" to be accurate within 6 feet but,
"Above sea level" was anything up to 30 feet amiss, I checked this at
Mevagissey harbour which is not too far from Newlyn which is Tidal datum.

--
Ken Ward

"Society for the production of Maritime Reefs using MerseyRail 142's"
(For membership email... mersey142.splash@ntlworld.com)
"Leave the Mobile Phone at home day Oct 25th 2006"

In article <1159216107.670332.320640@e3g2000cwe.. com>, Jerry
A <jerry.alderson@virgin.net> writes
>Paul Matthews wrote:
>> speedos aren't accurate - they are deliberably overrated so you can't use it
>> as a defence in speeding convictions (i.e I was going 30 according to my
>> speedo m'lord) - I found my speedo is 5%ish above what the satnav says.
>>
>> last time i used my satnav on a train we were being pulled behind a 67 doing
>> just over a ton according to the satnav anyway.
>>
>> paul
>
>Has anyone ever tried hooking up a GPS to a laptop? I'd be interested
>ot know how the comptuer can grab the information and do something
>useful with it.
>
>For example, can you stream the timestamp and co-ordinates into a text
>file, or even an Excel spreadsheet?
>
>Jerry A.
>

If you want there is a programme that will show you all the data thats
coming off the sat but its rather meaningless to most. It does however
show the signal strength and locations of the sats etc. Theres one
"Navigator" with the Leadtek series of receivers downloadable from their
web site, should work with other units...
--
Tony Sayer

In message <1159219093.10981.0@proxy01.news.clara.net>, at 22:14:37 on
Mon, 25 Sep 2006, Nigel Pendse <nigelp@clara.co.uk> remarked:
>So, I conclude that speeds are very accurate, but positions may be a few
>feet out.

GPS vertical positioning is inherently less accurate than horizontal.
--
Roland Perry