Garmin GPS - Disadvantages of WAAS/EGNOS?

Author

Disadvantages of WAAS/EGNOS?

Ramon F Herrera

2006-12-15, 10:33 pm

WAAS/EGNOS seem to be the best thing since sliced bread:

http://www.kowoma.de/en/gps/waas_egnos.htm

How come the Garmin GPS come with that cool feature disabled? When I
reset my GPS, WAAS/EGNOS is turned off.

Is it turned off in Magellans and Tomtoms?

-Ramon F Herrera

Jack Erbes

2006-12-15, 10:33 pm

Ramon F Herrera wrote:
> WAAS/EGNOS seem to be the best thing since sliced bread:
>
> http://www.kowoma.de/en/gps/waas_egnos.htm
>
> How come the Garmin GPS come with that cool feature disabled? When I
> reset my GPS, WAAS/EGNOS is turned off.
>
> Is it turned off in Magellans and Tomtoms?
>

To improve performance. Most newbies to GPS don't know what it is and
whether or not they want it on or off so leaving it off initially
presents the best performance.

I don't know about the other brands.

Jack

--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)

2006-12-15, 10:33 pm

Well, for one thing, it uses more battery power. It's a minor issue,
but ...

Arthur Hass

Ramon F Herrera wrote:
> WAAS/EGNOS seem to be the best thing since sliced bread:
>
> http://www.kowoma.de/en/gps/waas_egnos.htm
>
> How come the Garmin GPS come with that cool feature disabled? When I
> reset my GPS, WAAS/EGNOS is turned off.
>
> Is it turned off in Magellans and Tomtoms?
>
> -Ramon F Herrera
>

Ramon F Herrera

2006-12-15, 10:33 pm

Ed wrote:
> Well, for one thing, it uses more battery power. It's a minor issue,
> but ...
>
> Arthur Hass

It makes sense, but I should add that the WAAS/EGNOS feature is turned
off in my battery-less StreetPilot 2730 as well. Then again, there's
the performance issue.

-Ramon

Burnie M

2006-12-16, 4:33 am

A receiver with WAAS enabled will take a little longer to acquire a
position

Also, when in an area where you can receive a WAAS signal but you are
outside the intended coverage area of the correction then WAAS will
make your position less accurate (Australia for instance).

On 15 Dec 2006 18:50:38 -0800, "Ramon F Herrera" <ramon@conexus.net>
wrote:

>WAAS/EGNOS seem to be the best thing since sliced bread:
>
> http://www.kowoma.de/en/gps/waas_egnos.htm
>
>How come the Garmin GPS come with that cool feature disabled? When I
>reset my GPS, WAAS/EGNOS is turned off.
>
>Is it turned off in Magellans and Tomtoms?
>
>-Ramon F Herrera

Andy

2006-12-16, 4:33 am

Burnie M wrote:
> A receiver with WAAS enabled will take a little longer to acquire a
> position
>
> Also, when in an area where you can receive a WAAS signal but you are
> outside the intended coverage area of the correction then WAAS will
> make your position less accurate (Australia for instance).
>
>
>
> On 15 Dec 2006 18:50:38 -0800, "Ramon F Herrera" <ramon@conexus.net>
> wrote:
>
>

True. According to the 76CSx manual,

"Currently, enabling WAAS on your GPSMAP 76CSx in regions that are not
supported by ground stations, may not improve accuracy, even when
receiving signals from an SBAS satellite. In fact, it can degrade the
accuracy to less than that provided by GPS satellites alone. For this
reason, when you enable WAAS on your Garmin GPS receiver, the receiver
automatically uses the method that achieves the best accuracy."

Wonder if this is a normal feature for WAAS enabled GPS'?

--
Andy

John W Montgomery

2006-12-16, 4:33 am

Stop screwing around! WAAS is the only way to go now that they have =
moved the sats! 48 & 51 are full bar and are usable even inside. Leave =
it on and enjoy. All this other crap I hear is years old! Today is =
12/15/06 and WAAS is alive and well and working great! On the west coast =
here I have 48,51 & 35 FULL bar to choose from and ALL are working fine. =
So stop whining and use WAAS! I am and enjoying it!
JOHN

Lee

2006-12-16, 4:33 am

"John W Montgomery" <jwm@san.rr.com> wrote in message
news:4583a087$0$1330
3$4c368faf@roadrunne
r.com...
Stop screwing around! WAAS is the only way to go now that they have moved
the sats! 48 & 51 are full bar and are usable even inside. Leave it on and
enjoy. All this other crap I hear is years old! Today is 12/15/06 and
WAAS is alive and well and working great! On the west coast here I have
48,51 & 35 FULL bar to choose from and ALL are working fine. So stop whining
and use WAAS! I am and enjoying it!
JOHN

Are we talking US or UK?

Rudolpho

2006-12-16, 7:33 am

Lee schreef:
> "John W Montgomery" <jwm@san.rr.com> wrote in message
> news:4583a087$0$1330
3$4c368faf@roadrunne
r.com...
> Stop screwing around! WAAS is the only way to go now that they have moved
> the sats! 48 & 51 are full bar and are usable even inside. Leave it on and
> enjoy. All this other crap I hear is years old! Today is 12/15/06 and
> WAAS is alive and well and working great! On the west coast here I have
> 48,51 & 35 FULL bar to choose from and ALL are working fine. So stop whining
> and use WAAS! I am and enjoying it!
> JOHN
>
> Are we talking US or UK?

It must be US. In Holland I only received sat 51 ONCE.

--

Rudolpho
A program is never finished until the programmer dies.

Ramon F Herrera

2006-12-16, 10:33 am

Lee wrote:
> "John W Montgomery" <jwm@san.rr.com> wrote in message
> news:4583a087$0$1330
3$4c368faf@roadrunne
r.com...
> Stop screwing around! WAAS is the only way to go now that they have moved
> the sats! 48 & 51 are full bar and are usable even inside. Leave it on and
> enjoy. All this other crap I hear is years old! Today is 12/15/06 and
> WAAS is alive and well and working great! On the west coast here I have
> 48,51 & 35 FULL bar to choose from and ALL are working fine. So stop whining
> and use WAAS! I am and enjoying it!
> JOHN
>
> Are we talking US or UK?

Or Australia?

Who is whining? I read the whole thread and nobody is whining.

-Ramon

Ted Edwards

2006-12-16, 10:33 pm

Ramon F Herrera wrote:
> WAAS/EGNOS seem to be the best thing since sliced bread:
>
> http://www.kowoma.de/en/gps/waas_egnos.htm
>
> How come the Garmin GPS come with that cool feature disabled? When I
> reset my GPS, WAAS/EGNOS is turned off.

WASS is not available everywhere although it's availability is
improving. My GPS-V has a WAAS enabled 12 channel receiver. With WAAS
enabled it has 10 channels available for GPS satellites instead of 12.
So if I'm in an area with no or poor WAAS reception but good sky view
and on a good day for satellite geometry, I'm better off with WAAS off.
This assumes that I know what it is and/or have read the manual. :-)
Even here (in southwest Canada) I usually have it on - I do like that
factor of two improvement in "accuracy".

Ted

Andy

2006-12-17, 4:33 am

Ted Edwards wrote:
> Ramon F Herrera wrote:
>
> WASS is not available everywhere although it's availability is
> improving. My GPS-V has a WAAS enabled 12 channel receiver. With WAAS
> enabled it has 10 channels available for GPS satellites instead of 12.
> So if I'm in an area with no or poor WAAS reception but good sky view
> and on a good day for satellite geometry, I'm better off with WAAS off.
> This assumes that I know what it is and/or have read the manual. :-)
> Even here (in southwest Canada) I usually have it on - I do like that
> factor of two improvement in "accuracy".
>
> Ted

Some receivers, like the 76CSx, automatically toggle WAAS off/on
depending if it is giving better accuracy.

--
Andy

Seagull

2006-12-18, 12:33 pm

In alt.satellite.gps Ramon F Herrera <ramon@conexus.net> wrote:
>
> It makes sense, but I should add that the WAAS/EGNOS feature is turned
> off in my battery-less StreetPilot 2730 as well. Then again, there's
> the performance issue.

That, and 3-meter accuracy is overkill for a street navigator.

Cheers,
John

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Rudolpho

2006-12-18, 10:33 pm

Seagull wrote:
> In alt.satellite.gps Ramon F Herrera <ramon@conexus.net> wrote:
>
> That, and 3-meter accuracy is overkill for a street navigator.

I don't agree. If the error is too great, you might be driving on a
parallel road that leads to a ferry landing instead of a bridge.
--

Rudolpho
A program is never finished until the programmer dies.

Seagull

2006-12-18, 10:33 pm

In alt.satellite.gps.garmin Rudolpho <a@b.invalid> wrote:
>
> I don't agree. If the error is too great, you might be driving on a
> parallel road that leads to a ferry landing instead of a bridge.

If you need 3-meter accuracy while driving, then perhaps the GPS
isn't your biggest concern. :)

Seriously, I have a hard time believing that there are many real-world
road configurations where parallel streets are less than 30 feet from
center to center. And even in those instances, the GPS's lock-to-road
algorithm is going to be an overriding effect.

Cheers,
John

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Jack Erbes

2006-12-18, 10:33 pm

Seagull wrote:
> In alt.satellite.gps.garmin Rudolpho <a@b.invalid> wrote:
>
> If you need 3-meter accuracy while driving, then perhaps the GPS
> isn't your biggest concern. :)
>
> Seriously, I have a hard time believing that there are many real-world
> road configurations where parallel streets are less than 30 feet from
> center to center. And even in those instances, the GPS's lock-to-road
> algorithm is going to be an overriding effect.

I wonder if the algorithm uses your heading to decide which vector to
use for lock-to-road when you are on a freeway where the separation
between the left hand lanes can often get down to 20-30 feet or even
less at times.

I don't like lock to road and never turn it on. It just seems to me
like an imprudent thing to do for some reason. Besides, the map data is
supposed to represent where the roads really are, that is the acid test
and I want to know how good or bad it is.

Jack

--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)

Ramon F Herrera

2006-12-18, 10:33 pm

Seagull wrote:
> In alt.satellite.gps.garmin Rudolpho <a@b.invalid> wrote:
>
> If you need 3-meter accuracy while driving, then perhaps the GPS
> isn't your biggest concern. :)
>
> Seriously, I have a hard time believing that there are many real-world
> road configurations where parallel streets are less than 30 feet from
> center to center. And even in those instances, the GPS's lock-to-road
> algorithm is going to be an overriding effect.
>

You folks are incorrectly assuming that the GPS units are always
working at top accuracy. A few weeks ago my brother and I were in
Manhattan, he as a driver, I as a navigator. It was night and the GPS
was a whole street block off due to all the skyscrapers. I told my
brother to enter into a street and at the end of it the street lights
were facing the other way. My brother said: "What the heck?" and I
replied: "Perhaps the wind turned them around?". Then a couple of very
pissed cops approached us. I don't have to tell you that we were going
the wrong way, for several blocks.

In other cases you have two parallel lanes separated by a very low
wall, and the GPS assumes that you are on the other side of the wall.

-Ramon

Ron Lee

2006-12-18, 10:33 pm

"Ramon F Herrera" <ramon@conexus.net> wrote:

>You folks are incorrectly assuming that the GPS units are always
>working at top accuracy. A few weeks ago my brother and I were in
>Manhattan, he as a driver, I as a navigator. It was night and the GPS
>was a whole street block off due to all the skyscrapers. I told my
>brother to enter into a street and at the end of it the street lights
>were facing the other way. My brother said: "What the heck?" and I
>replied: "Perhaps the wind turned them around?". Then a couple of very
>pissed cops approached us. I don't have to tell you that we were going
>the wrong way, for several blocks.
>
>In other cases you have two parallel lanes separated by a very low
>wall, and the GPS assumes that you are on the other side of the wall.
>
>-Ramon
>
GPS is an aid. That does relieve the user of observing street signs,
noting road conditions and all other normal and prudent actions
required to drive safely.

Ron Lee

Jack Erbes

2006-12-19, 7:33 am

Ramon F Herrera wrote:

> Seagull wrote:
>
>
>
> You folks are incorrectly assuming that the GPS units are always
> working at top accuracy. A few weeks ago my brother and I were in
> Manhattan, he as a driver, I as a navigator. It was night and the GPS
> was a whole street block off due to all the skyscrapers. I told my
> brother to enter into a street and at the end of it the street lights
> were facing the other way. My brother said: "What the heck?" and I
> replied: "Perhaps the wind turned them around?". Then a couple of very
> pissed cops approached us. I don't have to tell you that we were going
> the wrong way, for several blocks.
>
> In other cases you have two parallel lanes separated by a very low
> wall, and the GPS assumes that you are on the other side of the wall.
>

I'd turn the lock to road feature off and use my eyes and head to sort
it out. I'm not going to let the GPS decide for me what road I'm on.

I'm thinking maybe some people are expecting a little too much from
their GPS. If you hit somebody because you're driving the wrong way up
a wrong way street I'm thinking it is not the GPS receiver's fault.
Remember the "lawyer screen" when it started up? It's up to you to get
it right.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

Seagull

2006-12-19, 3:33 pm

In alt.satellite.gps Jack Erbes <jackerbes@adelphia.net> wrote:
>
> I wonder if the algorithm uses your heading to decide which vector to
> use for lock-to-road when you are on a freeway where the separation
> between the left hand lanes can often get down to 20-30 feet or even
> less at times.

I can't speak for units other than Garmin. For the StreetPilot 2xx0
series it appears to assume you are following the route until the
separation is great enough that it knows you're on the other branch.
If routing isn't in effect, it assumes you are staying on the same road
(ie, not leavin ghte highway). For a splitting interestate, it appears
to use heading.

> I don't like lock to road and never turn it on. It just seems to me
> like an imprudent thing to do for some reason. Besides, the map data is
> supposed to represent where the roads really are, that is the acid test
> and I want to know how good or bad it is.

Alas, in the past year or so NavTeq started exaggerating on- and off-
ramp positions. Presumably to clarify map detail. It's a legitimate
cartography technique, but that doesn't mean there aren't opinions on
wwhether or not it should be employed.

Cheers,
John

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Seagull

2006-12-19, 3:33 pm

In alt.satellite.gps Ramon F Herrera <ramon@conexus.net> wrote:
>
> You folks are incorrectly assuming that the GPS units are always
> working at top accuracy.

If it's not, WAAS correction isn't going to help you. WAAS is supplemental
data, not a replacement for a solid lock.

> pissed cops approached us. I don't have to tell you that we were going
> the wrong way, for several blocks.

The primary navigation computer in any vehicle lies between the drivers
ears. Tell your brother not to shut it off.

Cheers,
-+JLS

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Rudolpho

2006-12-19, 10:33 pm

Seagull wrote:
> In alt.satellite.gps.garmin Rudolpho <a@b.invalid> wrote:
>
> If you need 3-meter accuracy while driving, then perhaps the GPS
> isn't your biggest concern. :)

I don't drive. I'm living very close to my work and public transport.

> Seriously, I have a hard time believing that there are many real-world
> road configurations where parallel streets are less than 30 feet from
> center to center. And even in those instances, the GPS's lock-to-road
> algorithm is going to be an overriding effect.

That will cause the mistake. The GPS may lock on the wrong road. In
worse conditions I've experienced position errors off 250 meters with my
Garmin 60 CSx
--

Rudolpho
A program is never finished until the programmer dies.

Dale DePriest

2006-12-20, 12:33 pm

Jack Erbes wrote:

>
> I don't like lock to road and never turn it on. It just seems to me
> like an imprudent thing to do for some reason. Besides, the map data is
> supposed to represent where the roads really are, that is the acid test
> and I want to know how good or bad it is.
>
> Jack
>

I am not a fan of road lock either but I use it on Garmin units since
the auto navigation tends to fail and cause false reroutes if it is
turned off. I have other systems that work fine with road lock off but
not Garmin ones.

Dale
--
_ _ Dale DePriest
/`) _ // http://users.cwnet.com/dalede
o/_/ (_(_X_(` For GPS and GPS/PDAs

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