Which GPS ?

In article <[email hidden]>, "Nick
(Scots)" <[email hidden]> writes

Quoted message said:

For hillwalking and forrested MTBing ?

The EDGE ?

I would prefer a unit that takes standard batteries so that I don't need
to charge it before I go and I can carry spares easily.

A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
~£170 for the Edge 205 or ~£240 for the 305)

On the plus side the Edge receivers do use the SiRFStarIII GPS chipset
which makes them very good in poor reception areas (like your forests).
Garmin have said they will be using SiRFStarIII in other receivers now
as well (I think there are new models in the eTrex and 60 ranges that
will use it).

Quoted message said:

or Garmin's GPS-60C Color Mapping ?

Bit big and expensive for my liking and the available off-road maps in
the UK don't make having a mapping receiver much of a plus :-(

Quoted message said:

Or the Mio PDA with flipup arial ?

I have one of those for car nav and like most PDA units it is not very
rugged. It also won't last more than a few hours of use (I think the
book said 4). I have a handlebar mount for it but have not used in on
the MTB as I am happy with my Geko 201 and don't want to shake the Mio
to bits or smash it in a spill.

--

Dominic Sexton

Dominic Sexton said:

A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
~£170 for the Edge 205 or ~£240 for the 305)

Not sure how well this'll track a signal in a forest. My 301 is a bit
hit & miss in these conditions.
--
Mike
Some pictures & bad html here http://www.prog99.com

Bitstring <[email hidden]>, from the
wonderful person Mike <[email hidden]> said

Quoted message said:

Dominic Sexton said:

A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
~£170 for the Edge 205 or ~£240 for the 305)

Quoted message said:

Not sure how well this'll track a signal in a forest. My 301 is a bit
hit & miss in these conditions.

My =60C= is a bit hit & miss in those conditions too, especially when
the trees are in full leaf &/or have just been rained on. Even with an
external antenna (which is at least an option with a 60C) I still lose
maybe 10-20% of trackpoints from the breadcrumb trail, unless the
satellite constellation happens to be 'just right' with 4 or 5 nearly
straight up (it's the sideways ones that have to penetrate maybe 100m of
leaves which die off first).

--
GSV Three Minds in a Can
Contact recommends the use of Firefox; SC recommends it at gunpoint.

In article <[email hidden]>, Dominic Sexton
<[email hidden]> writes

Quoted message said:

In article <[email hidden]>, "Nick
(Scots)" <[email hidden]> writes

Quoted message said:

For hillwalking and forrested MTBing ?

The EDGE ?

I would prefer a unit that takes standard batteries so that I don't
need to charge it before I go and I can carry spares easily.

A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
~£170 for the Edge 205 or ~£240 for the 305)

On the plus side the Edge receivers do use the SiRFStarIII GPS chipset
which makes them very good in poor reception areas (like your forests).
Garmin have said they will be using SiRFStarIII in other receivers now
as well (I think there are new models in the eTrex and 60 ranges that
will use it).

Quoted message said:

or Garmin's GPS-60C Color Mapping ?

Bit big and expensive for my liking and the available off-road maps in
the UK don't make having a mapping receiver much of a plus :-(

Quoted message said:

Or the Mio PDA with flipup arial ?

I have one of those for car nav and like most PDA units it is not very
rugged. It also won't last more than a few hours of use (I think the
book said 4). I have a handlebar mount for it but have not used in on
the MTB as I am happy with my Geko 201 and don't want to shake the Mio
to bits or smash it in a spill.

Now that I've got it working, I can boast an iPAQ hx2410 in conjunction
with a Holux GPSlim 236 Bluetooth GPS.

I don't want it for walking - I have my Garmin GPS 12 for that.

The new set up will cost you around 380quid - 280-ish for the iPAQ and
between 70 and 100 quid for the GPS (depends where you get it)

The iPAQ is not waterproof and the batteries don't give a lot of service
before recharging. The GPS battery is much better. I would use it to
find my position on a hill if necessary, but not to log my track. It
will display my track on OS 1:50,000 or 1:25,000 though and is excellent
when compared with the Garmin 12 - I don't need to fiddle with the map
in a high wind for example. (Please let no one misinterpret my use of
the iPAQ)

I've opted for the iPAQ and GPS system in preference over a normal
SAT/NAV system which doesn't use OS maps. I need to locate "Off road"
locations using grid refss and as far as I know only the Garmin Quest
lets you use Grid refs.

--
Bill Grey
http://www.billboy.co.uk

GSV Three Minds in a Can said:

Quoted message said:

Quoted message said:

A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
~£170 for the Edge 205 or ~£240 for the 305)

Quoted message said:

Not sure how well this'll track a signal in a forest. My 301 is a bit
hit & miss in these conditions.

My =60C= is a bit hit & miss in those conditions too, especially when
the trees are in full leaf &/or have just been rained on.

No altimeter in yours?

Never really tested this, but I think a GPS with an altimeter should work
better in forests. I've noticed with my old GPS12 that when I got bad
reception in a forest the altitude used to go pretty screwy, which would
throw the position out, and with only three satellites you don't get
altitude at all.

One trick for getting a quicker fix when you first switch a GPS on is to
manually enter the altitude, since that helps to compute a more accurate 2D
position. I don't know if the altimeter in a GPS does the same thing but
I'd hope that it would, so even with bad reception, the altimeter should
help to keep the position more accurate, and of course will continue to give
you a believable altitude reading even when you don't have enough satellites
to get a GPS altitude.

Paul

Bitstring <[email hidden]>, from the wonderful
person Paul Saunders <[email hidden]> said

Quoted message said:

GSV Three Minds in a Can said:

Quoted message said:

> A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
> ~£170 for the Edge 205 or ~£240 for the 305)

Quoted message said:

Not sure how well this'll track a signal in a forest. My 301 is a bit
hit & miss in these conditions.

My =60C= is a bit hit & miss in those conditions too, especially when
the trees are in full leaf &/or have just been rained on.

No altimeter in yours?

Nope, that's why it's a 'C' and not a 'CS'. 8>.

Quoted message said:

Never really tested this, but I think a GPS with an altimeter should work
better in forests.

I'm not convinced - either that having altitude will get you a better
fix, or that the CS is smart enough to use altitude that way anyway..

--
GSV Three Minds in a Can
Contact recommends the use of Firefox; SC recommends it at gunpoint.

druidh said:

Some of the car systems use intertia to "estimate" position in the event
of a signal loss.

Some also take a feed from the speedometer.

AJH

GSV Three Minds in a Can said:

Bitstring <[email hidden]>, from the wonderful
person Paul Saunders <[email hidden]> said

Quoted message said:

GSV Three Minds in a Can said:

>> A Geko 201 with bike mount will cost a lot less (~£100 as opposed to
>> ~£170 for the Edge 205 or ~£240 for the 305)

> Not sure how well this'll track a signal in a forest. My 301 is a bit
> hit & miss in these conditions.

My =60C= is a bit hit & miss in those conditions too, especially when
the trees are in full leaf &/or have just been rained on.

No altimeter in yours?

Nope, that's why it's a 'C' and not a 'CS'. 8>.

Quoted message said:

Never really tested this, but I think a GPS with an altimeter should work
better in forests.

I'm not convinced - either that having altitude will get you a better
fix, or that the CS is smart enough to use altitude that way anyway..

Some of the car systems use intertia to "estimate" position in the event
of a signal loss. I suspect that there would be insufficient interia at
walking speed to enable this.

druidh

druidh said:

Some of the car systems use intertia to "estimate" position in the
event of a signal loss. I suspect that there would be insufficient
interia at walking speed to enable this.

Actually there is. Garmin does it. When it loses the signal it continues
moving in the same direction at the same speed for around 30 seconds before
stopping. I've tried walking straight into my house then watching what
happens. I stop walking, the GPS loses the signal, but it keeps on moving.
I've seen the GPS "walk" halfway up the street before stopping!

Paul

Bitstring <[email hidden]>, from the
wonderful person druidh <[email hidden]> said
<snip>

Quoted message said:

Some of the car systems use intertia to "estimate" position in the
event of a signal loss. I suspect that there would be insufficient
interia at walking speed to enable this.

Nope, hand held units do it too, with hilarious results if you corner.
All it means is that they assume you keep doing the same velocity
(speed, direction) until they can prove otherwise .. although typically
they'll time out after a few 10s of seconds because else it gets silly.

The latest 60C firmware actually doesn't drop trackpoints under those
conditions (although it still updates the screen position afaict), so
when you download the track later you can see where reception was dodgy
- you get a point every 20 or 30m instead of every 10 (or whatever
you'd asked for). or no points at all for 60m, and then an alert
message.

--
GSV Three Minds in a Can
Contact recommends the use of Firefox; SC recommends it at gunpoint.

In article <[email hidden]>, GSV Three Minds in a Can
<[email hidden]> writes

Quoted message said:

Bitstring <[email hidden]>, from the
wonderful person druidh <[email hidden]> said
<snip>

Quoted message said:

Some of the car systems use intertia to "estimate" position in the
event of a signal loss. I suspect that there would be insufficient
interia at walking speed to enable this.

Nope, hand held units do it too

I think druidh was referring to real inertial assisting using
accelerometers rather than the software extrapolation.

--

Dominic Sexton

Dominic Sexton said:

In article <[email hidden]>, GSV Three Minds in a Can
<[email hidden]> writes

Quoted message said:

Bitstring <[email hidden]>, from the
wonderful person druidh <[email hidden]> said
<snip>

Quoted message said:

Some of the car systems use intertia to "estimate" position in the
event of a signal loss. I suspect that there would be insufficient
interia at walking speed to enable this.

Nope, hand held units do it too

I think druidh was referring to real inertial assisting using
accelerometers rather than the software extrapolation.

Correct - some are capable of extrapolatng based on changes in
direction. Of course, it's simpler when you're following roads as
opposed to wandering over countryside.

druidh

It may be bulky and a bit dated but the Magellan Meridian range have
excellent reception. I get reception in the house away from the window and
heavily forested areas have not often created a problem. I also like the SD
expansion as I keep street level mapping on Europe on it as well so if I get
really lost at least I can wander towards the nearest road!

Jon

"druidh" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Dominic Sexton said:

In article <[email hidden]>, GSV Three Minds in a Can
<[email hidden]> writes

Quoted message said:

Bitstring <[email hidden]>, from the
wonderful person druidh <[email hidden]> said
<snip>

> Some of the car systems use intertia to "estimate" position in the
> event of a signal loss. I suspect that there would be insufficient
> interia at walking speed to enable this.

Nope, hand held units do it too

I think druidh was referring to real inertial assisting using
accelerometers rather than the software extrapolation.

Correct - some are capable of extrapolatng based on changes in direction.
Of course, it's simpler when you're following roads as opposed to
wandering over countryside.

druidh

JRS said:

It may be bulky and a bit dated but the Magellan Meridian range have
excellent reception. I get reception in the house away from the window and
heavily forested areas have not often created a problem. I also like the SD
expansion as I keep street level mapping on Europe on it as well so if I get
really lost at least I can wander towards the nearest road!

Jon

Via the unpassable river and the 1,000 ft cliff no doubt :-)

druidh

druidh said:

Quoted message said:

if I get really lost at least I can wander
towards the nearest road!

Quoted message said:

Via the unpassable river and the 1,000 ft cliff no doubt :-)

In a whiteout! ;-)

Paul

AJH said:

druidh said:

Some of the car systems use intertia to "estimate" position in the event
of a signal loss.

Some also take a feed from the speedometer.

It helps the Sat Nav to know that if you are in a car it must be on a
road.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

I have a fat friend (honest!) who sometimes can not match the optimism of
the route downloaded from anquet and invariably hitch hikes home :-)

"Paul Saunders" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

druidh said:

Quoted message said:

if I get really lost at least I can wander
towards the nearest road!

Quoted message said:

Via the unpassable river and the 1,000 ft cliff no doubt :-)

In a whiteout! ;-)

Paul

Paul Saunders said:

GSV Three Minds in a Can wrote:

Quoted message said:

Quoted message said:

Quoted message said:

> A Geko 201 with bike mount will cost a lot less (#100 as opposed to
> #170 for the Edge 205 or #240 for the 305)

Quoted message said:

Not sure how well this'll track a signal in a forest. My 301 is a bit
hit & miss in these conditions.

My =60C= is a bit hit & miss in those conditions too, especially when
the trees are in full leaf &/or have just been rained on.

Quoted message said:

No altimeter in yours?

Quoted message said:

Never really tested this, but I think a GPS with an altimeter should work
better in forests. I've noticed with my old GPS12 that when I got bad
reception in a forest the altitude used to go pretty screwy, which would
throw the position out, and with only three satellites you don't get
altitude at all.

Quoted message said:

One trick for getting a quicker fix when you first switch a GPS on is to
manually enter the altitude, since that helps to compute a more accurate 2D
position. I don't know if the altimeter in a GPS does the same thing but
I'd hope that it would, so even with bad reception, the altimeter should
help to keep the position more accurate, and of course will continue to give
you a believable altitude reading even when you don't have enough satellites
to get a GPS altitude.

This would be possible, and IMHO a good idea, but AFAIK no current GPS
does it. I suspect it may have something to do with standards such as
NMEA, i.e., GPS position should be calculated purely on the basis of
GPS signals. The problem is that if the altitude was wrongly
calibrated, as will often be the case at switch on in poor reception
conditions, the consequently wildly wrong altitude will give a wildly
wrong position.

--
Chris Malcolm [email hidden] +44 (0)131 651 3445 DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

Paul Saunders said:

druidh wrote:

Quoted message said:

Quoted message said:

Some of the car systems use intertia to "estimate" position in the
event of a signal loss. I suspect that there would be insufficient
interia at walking speed to enable this.

Quoted message said:

Actually there is. Garmin does it. When it loses the signal it continues
moving in the same direction at the same speed for around 30 seconds before
stopping. I've tried walking straight into my house then watching what
happens. I stop walking, the GPS loses the signal, but it keeps on moving.
I've seen the GPS "walk" halfway up the street before stopping!

This can be a useful way of setting a waypoint where there is no
signal. Walk to it in a straight line at a constant speed from a place
of good reception.

--
Chris Malcolm [email hidden] +44 (0)131 651 3445 DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]