| Author |
Message |
Jim Stewart
Guest
|
 Posted:
Tue Dec 27, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
David R Brooks wrote:
| Quote: | Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
|
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes. |
|
| Back to top |
|
 |
Al Balmer
Guest
|
| Posted:
Wed Dec 28, 2005 1:11 am Post subject:
Re: GPS digital navigation map data |
|
|
On Sat, 24 Dec 2005 13:37:28 -0800, "Michael R. Kesti"
<mrkesti@nospam.net> wrote:
| Quote: | As I read him, he stated that aviation GPS units
base on much more reliable data than "personal" GPS's
(though I'm not sure what this latter amounts to).
I am referring to the handhelds that sell in the 100's of dollars range,
such as those such as the Magellan unit I own, and for which there is no
way to obtain updated data.
|
I can't speak for Magellan, but maps can be uploaded to Garmin units,
and updated maps are periodically available. Firmware updates are
usually free.
--
Al Balmer
Sun City, AZ |
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| Back to top |
|
|
Anton Erasmus
Guest
|
| Posted:
Wed Dec 28, 2005 9:15 am Post subject:
Re: GPS digital navigation map data |
|
|
On Tue, 27 Dec 2005 22:28:19 -0800, David R Brooks
<davebXXX@iinet.net.au> wrote:
| Quote: | Jim Stewart wrote:
David R Brooks wrote:
Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes.
When I was learning coastal navigation, about 15 years ago, my
instructor was over the moon about GPS. In fairness, he didn't
specifically say to dump my paper charts, but he did say to dump my
sextant, & use the saved cash to buy a back-up GPS unit. I still take
leave to differ with that view.
|
I read an article In one of the Electronic trade magazine some time
ago. This article was written by an engineer who had been evaluating
the GPS technology, chipsets and devices available at the time. One of
his hobbies was sailing, and he took the several GPS devices along on
a weekend sailing trip around some islands in the west indies.
One thing he picked up was that very few of the devices gave a
confidence level (Or a tolerance) on the highly precise value
displayed on the device.
He also said that if he had relied on the GPS devices on a particilar
trip where he had a 100m wide channel to navigate, he would have ended
up on the rocks. I personaly think that devices should display a
precision related to the acuracy of the data.
People tend to believe the numbers even if they should be ignored.
If one displays a range for instance with an accuracy of +- 1m, then
display say 143 m, not 143.000 m. Better would be to display 143 +-1m
or (142 to 144m).
On a GPS device with a map display, a circle could be displayed that
indicated that one is somewhere in the circle in stead of a dot. If
the minimum height intersects the ground anywhere in this region,
an alarm should sound.
Regards
Anton Erasmus |
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| Back to top |
|
|
David R Brooks
Guest
|
| Posted:
Wed Dec 28, 2005 9:15 am Post subject:
Re: GPS digital navigation map data |
|
|
Jim Stewart wrote:
| Quote: | David R Brooks wrote:
Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes.
When I was learning coastal navigation, about 15 years ago, my |
instructor was over the moon about GPS. In fairness, he didn't
specifically say to dump my paper charts, but he did say to dump my
sextant, & use the saved cash to buy a back-up GPS unit. I still take
leave to differ with that view. |
|
| Back to top |
|
|
Not Really Me
Guest
|
| Posted:
Wed Dec 28, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
<SNIP>
| Quote: |
Tell that to aircraft pilots who do "trust their lives"
to the accuracy of the GPS info.
This seems an apples to oranges comparison as I imagine the data used in
personal GPS receivers is less accurate, less often updated, and no where
near as trustable as that used in the GPS receivers used in aviation.
While there is nothing to prevent a pilot from taking any "NAV AID" he wants |
on a plane including a toy compass and a 30 year old map, there are
regulations regarding NAV AIDs designed to be mounted/installed in aircraft.
Any device to be used for navigation must be designed against certain
standards such as RTCA DO-178B for software and then "type certified" by the
FAA (US, other countries/other agencies) for use in that type of plane.
In addition, data to be used in the NAV AID is covered by RTCA standard
DO-200A - Standards for Processing Aeronautical Data. All data to
be used in aviation must be handled in accordance with this standard.
--
Scott
Validated Software Corp. |
|
| Back to top |
|
|
Al Balmer
Guest
|
| Posted:
Wed Dec 28, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
On Wed, 28 Dec 2005 09:44:03 +0200, Anton Erasmus
<nobody@spam.prevent.net> wrote:
| Quote: | On Tue, 27 Dec 2005 22:28:19 -0800, David R Brooks
davebXXX@iinet.net.au> wrote:
Jim Stewart wrote:
David R Brooks wrote:
Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes.
When I was learning coastal navigation, about 15 years ago, my
instructor was over the moon about GPS. In fairness, he didn't
specifically say to dump my paper charts, but he did say to dump my
sextant, & use the saved cash to buy a back-up GPS unit. I still take
leave to differ with that view.
I read an article In one of the Electronic trade magazine some time
ago. This article was written by an engineer who had been evaluating
the GPS technology, chipsets and devices available at the time. One of
his hobbies was sailing, and he took the several GPS devices along on
a weekend sailing trip around some islands in the west indies.
|
Was "some time ago" prior to the removal of Selective Availability?
| Quote: | One thing he picked up was that very few of the devices gave a
confidence level (Or a tolerance) on the highly precise value
displayed on the device.
He also said that if he had relied on the GPS devices on a particilar
trip where he had a 100m wide channel to navigate, he would have ended
up on the rocks. I personaly think that devices should display a
precision related to the acuracy of the data.
People tend to believe the numbers even if they should be ignored.
If one displays a range for instance with an accuracy of +- 1m, then
display say 143 m, not 143.000 m. Better would be to display 143 +-1m
or (142 to 144m).
On a GPS device with a map display, a circle could be displayed that
indicated that one is somewhere in the circle in stead of a dot.
|
At least some GPS units do exactly that, though it's usually a
separate screen. It wouldn't surprise me if all of them do.
| Quote: | If
the minimum height intersects the ground anywhere in this region,
an alarm should sound.
Seems useful only to pilots, and would require topographic maps, which |
are available but not needed by most lay GPS users.
--
Al Balmer
Sun City, AZ |
|
| Back to top |
|
|
Mark Moulding
Guest
|
| Posted:
Thu Dec 29, 2005 1:15 am Post subject:
Re: GPS digital navigation map data |
|
|
You might take a look at the US Census Bureau's Tiger/Line database. These
files are freely available, and contain the basic source data that all of
the (US, anyway) GPS mapping companies use for their products. Look at:
http://www.census.gov/geo/www/tiger/
These files contain information on all streets, geographic boundaries
(lakes, rivers, etc.) zip codes, railways, governmental boundaries (city,
count, state, military, parks, etc.) address information (including
left/right side and one-way) for all the streets. In short, it's all you'd
need to write your own mapping software (along with a bit of work, of
course).
The GPS and mapping companies (deLorme, Microsoft, AAA, MapQuest, etc.) then
supplement this information with phone-book databases to add points of
interest, freeway exit information, etc. They also invest quite a bit of
effort in producing routing algorithms to make use of this raw data, and
user interfaces to (hopefully) make it easy to use. Invariably, the raw
data is massaged into their own proprietary format for speed of access.
--
Mark
"I prefer heaven for climate, hell for company."
<Ray> wrote in message
news:43acd6f0$0$17708$afc38c87@news.optusnet.com.au...
| Quote: | GPS navigators such as TomTom, NavMan, Garmin, Magellan etc. become
increasingly popular.
Is there a common standard for the digital map data to be used on these
type of small embedded devices in which optimal route calculation can be
calculated?
Is it possible to access this data through some API, to use it in a PC
application?
Ray
|
|
|
| Back to top |
|
|
George Neuner
Guest
|
| Posted:
Thu Dec 29, 2005 9:15 am Post subject:
Re: GPS digital navigation map data |
|
|
On Sat, 24 Dec 2005 21:58:41 -0500, Gene S. Berkowitz
<first.last@comcast.net> wrote:
| Quote: | In article <43adc6da$0$24900$ba620e4c@news.skynet.be>,
adelcoGENE@zeverSKYNET.BE says...
"Gene S. Berkowitz" <first.last@comcast.net> schreef in bericht
news:MPG.1e178d2230f15b2e9896f4@newsgroups.comcast.net...
A pilot is not using a consumer-oriented GPS. He is using an aviation
GPS, with a Jeppesen database of beacons, approaches, and airports, that
is maintained via a monthly subscription.
Is he (and/or she)? Each one? Really?
Sure and guaranteed? How can you know?
They're the ones who DON'T fly into the terrain, or stray into
controlled airspace, or radio traffic control asking "Where am I?"
On my side I HAVE seen pilots fly with "consumer-oriented"
GPS-units, though not as a primary means of navigation, luckily.
|
Yes. I use a handheld to double check position. I do not navigate
with it [see below].
| Quote: | And don't come and tell me about "certified" units:
I didn't. Aviation units are designed to display the information of
interest to pilots, and to easily integrate with the other avionics
aboard the aircraft.
|
Aviation units compute location much faster. AFAIK there aren't any
consumer oriented units that can reliably locate themselves while
moving at 150 knots ... many turbocharged and/or multi engine aircraft
can cruise faster than that.
Also aviation units with navigation plot great circle courses rather
than straight lines.
| Quote: | unless I'm much mistaken not any single GPS unit has been certified
by any single European civil aviation authority.
..but that probably has more to do with the lack of European
manufacturers than any inherent problems with the devices themselves...
|
I think it's more because GPS is controlled by the U.S.
George
--
for email reply remove "/" from address |
|
| Back to top |
|
|
J. Clarke
Guest
|
| Posted:
Thu Dec 29, 2005 9:15 am Post subject:
Re: GPS digital navigation map data |
|
|
Anton Erasmus wrote:
| Quote: | On Tue, 27 Dec 2005 22:28:19 -0800, David R Brooks
davebXXX@iinet.net.au> wrote:
Jim Stewart wrote:
David R Brooks wrote:
Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes.
When I was learning coastal navigation, about 15 years ago, my
instructor was over the moon about GPS. In fairness, he didn't
specifically say to dump my paper charts, but he did say to dump my
sextant, & use the saved cash to buy a back-up GPS unit. I still take
leave to differ with that view.
I read an article In one of the Electronic trade magazine some time
ago. This article was written by an engineer who had been evaluating
the GPS technology, chipsets and devices available at the time. One of
his hobbies was sailing, and he took the several GPS devices along on
a weekend sailing trip around some islands in the west indies.
One thing he picked up was that very few of the devices gave a
confidence level (Or a tolerance) on the highly precise value
displayed on the device.
He also said that if he had relied on the GPS devices on a particilar
trip where he had a 100m wide channel to navigate, he would have ended
up on the rocks. I personaly think that devices should display a
precision related to the acuracy of the data.
|
The question is whether he would have ended up on the rocks due to
inaccuracy or to his failure to set the correct reference point (the
"datum"). If the GPS is using one datum and the charts another then even
if the GPS is giving accuracy to the nanometer its reading will differ from
that on the chart. This is something that most GPS users don't even seem
to be aware of.
| Quote: | People tend to believe the numbers even if they should be ignored.
If one displays a range for instance with an accuracy of +- 1m, then
display say 143 m, not 143.000 m. Better would be to display 143 +-1m
or (142 to 144m).
On a GPS device with a map display, a circle could be displayed that
indicated that one is somewhere in the circle in stead of a dot. If
the minimum height intersects the ground anywhere in this region,
an alarm should sound.
Regards
Anton Erasmus
|
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
|
| Back to top |
|
|
David R Brooks
Guest
|
| Posted:
Thu Dec 29, 2005 3:34 pm Post subject:
Re: GPS digital navigation map data |
|
|
Al Balmer wrote:
| Quote: | On Wed, 28 Dec 2005 09:44:03 +0200, Anton Erasmus
nobody@spam.prevent.net> wrote:
On Tue, 27 Dec 2005 22:28:19 -0800, David R Brooks
davebXXX@iinet.net.au> wrote:
Jim Stewart wrote:
David R Brooks wrote:
Don't know about standards, but I wouldn't expect any - they each want
to protect their turf.
More seriously, I was browsing a boating magazine in my doctor's rooms
recently, & hit an article in which a yachtsman nearly ran smack into
Diego Ramirez Is. (near Cape Horn), because it simply wasn't shown on
the electronic chart he was using.
Doesn't anyone sailing near the Horn
without real Admiralty charts deserve
what he/she gets? What little sailing
experience I've had tells me yes.
When I was learning coastal navigation, about 15 years ago, my
instructor was over the moon about GPS. In fairness, he didn't
specifically say to dump my paper charts, but he did say to dump my
sextant, & use the saved cash to buy a back-up GPS unit. I still take
leave to differ with that view.
I read an article In one of the Electronic trade magazine some time
ago. This article was written by an engineer who had been evaluating
the GPS technology, chipsets and devices available at the time. One of
his hobbies was sailing, and he took the several GPS devices along on
a weekend sailing trip around some islands in the west indies.
Was "some time ago" prior to the removal of Selective Availability?
One thing he picked up was that very few of the devices gave a
confidence level (Or a tolerance) on the highly precise value
displayed on the device.
He also said that if he had relied on the GPS devices on a particilar
trip where he had a 100m wide channel to navigate, he would have ended
up on the rocks. I personaly think that devices should display a
precision related to the acuracy of the data.
People tend to believe the numbers even if they should be ignored.
If one displays a range for instance with an accuracy of +- 1m, then
display say 143 m, not 143.000 m. Better would be to display 143 +-1m
or (142 to 144m).
On a GPS device with a map display, a circle could be displayed that
indicated that one is somewhere in the circle in stead of a dot.
At least some GPS units do exactly that, though it's usually a
separate screen. It wouldn't surprise me if all of them do.
If
the minimum height intersects the ground anywhere in this region,
an alarm should sound.
Seems useful only to pilots, and would require topographic maps, which
are available but not needed by most lay GPS users.
Also, take a look on comp.risks: there's an item in the current Risks |
bulletin on in-car GPS issues: as noted on this thread, they all derive
from a single database, which is *not* error-free. So using two
different makes of GPS won't help either. |
|
| Back to top |
|
|
Paul Keinanen
Guest
|
| Posted:
Thu Dec 29, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
On Sat, 24 Dec 2005 22:08:30 -0000, "karel"
<adelcoGENE@zeverSKYNET.BE> wrote:
| Quote: |
"Gene S. Berkowitz" <first.last@comcast.net> schreef in bericht
news:MPG.1e178d2230f15b2e9896f4@newsgroups.comcast.net...
In article <11qrbnurgr83u82@corp.supernews.com>, rowlett@atlascomm.net
says...
Would not a pilot be interested in exact location of airports and
various beacons? would there be any equivalent of uncharted shoals?
A pilot is not using a consumer-oriented GPS. He is using an aviation
GPS, with a Jeppesen database of beacons, approaches, and airports, that
is maintained via a monthly subscription.
Is he (and/or she)? Each one? Really?
Sure and guaranteed? How can you know?
On my side I HAVE seen pilots fly with "consumer-oriented"
GPS-units, though not as a primary means of navigation, luckily.
And don't come and tell me about "certified" units:
unless I'm much mistaken not any single GPS unit has been certified
by any single European civil aviation authority.
|
Would you do an approach without much assurance of the GPS satellite
signal quality ? Assuming that the SA would be suddenly switched on
during the approach (or a satellite would experience some sudden
problem), this could have quite serious consequences. For any critical
navigation, you really need some assurance about the signal quality.
A differential-GPS station can constantly verify the signal quality
from all satellites and broadcast this signal quality information to
nearby users (in addition to the differential correction). Without a
DGPS transmitter at every airport, I don't see how you could make a
safe approach with only a GPS receiver.
Paul |
|
| Back to top |
|
|
Guest
|
| Posted:
Thu Dec 29, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
| Quote: | You might take a look at the US Census Bureau's Tiger/Line database.
These files are freely available, and contain the basic source data that
all of the (US, anyway) GPS mapping companies use for their products.
Look at:
http://www.census.gov/geo/www/tiger/
These files contain information on all streets, geographic boundaries
(lakes, rivers, etc.) zip codes, railways, governmental boundaries (city,
count, state, military, parks, etc.) address information (including
left/right side and one-way) for all the streets. In short, it's all
you'd need to write your own mapping software (along with a bit of work,
of course).
The GPS and mapping companies (deLorme, Microsoft, AAA, MapQuest, etc.)
then supplement this information with phone-book databases to add points
of interest, freeway exit information, etc. They also invest quite a bit
of effort in producing routing algorithms to make use of this raw data,
and user interfaces to (hopefully) make it easy to use. Invariably, the
raw data is massaged into their own proprietary format for speed of
access.
--
Mark
"I prefer heaven for climate, hell for company."
|
Does anyone know if there is an equivalent to "US Census Bureau's Tiger/Line
database" in Australia? |
|
| Back to top |
|
|
Paul Keinanen
Guest
|
| Posted:
Thu Dec 29, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
On Wed, 28 Dec 2005 09:33:41 -0700, Al Balmer <albalmer@att.net>
wrote:
| Quote: | I read an article In one of the Electronic trade magazine some time
ago. This article was written by an engineer who had been evaluating
the GPS technology, chipsets and devices available at the time. One of
his hobbies was sailing, and he took the several GPS devices along on
a weekend sailing trip around some islands in the west indies.
Was "some time ago" prior to the removal of Selective Availability?
|
That is irrelevant as long as the system contains the option of SA.
How can you be sure that the SA is not activated tomorrow ?
Paul |
|
| Back to top |
|
|
Guest
|
| Posted:
Thu Dec 29, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
| Quote: | You might take a look at the US Census Bureau's Tiger/Line database.
These files are freely available, and contain the basic source data that
all of the (US, anyway) GPS mapping companies use for their products.
Look at:
http://www.census.gov/geo/www/tiger/
These files contain information on all streets, geographic boundaries
(lakes, rivers, etc.) zip codes, railways, governmental boundaries (city,
count, state, military, parks, etc.) address information (including
left/right side and one-way) for all the streets. In short, it's all
you'd need to write your own mapping software (along with a bit of work,
of course).
The GPS and mapping companies (deLorme, Microsoft, AAA, MapQuest, etc.)
then supplement this information with phone-book databases to add points
of interest, freeway exit information, etc. They also invest quite a bit
of effort in producing routing algorithms to make use of this raw data,
and user interfaces to (hopefully) make it easy to use. Invariably, the
raw data is massaged into their own proprietary format for speed of
access.
--
Mark
"I prefer heaven for climate, hell for company."
|
Dear Mark,
Thank you for your informative reply.
(I think your posting was the only relevant reply to the original question.)
Ray |
|
| Back to top |
|
|
J. Clarke
Guest
|
| Posted:
Thu Dec 29, 2005 5:15 pm Post subject:
Re: GPS digital navigation map data |
|
|
Paul Keinanen wrote:
| Quote: | On Sat, 24 Dec 2005 22:08:30 -0000, "karel"
adelcoGENE@zeverSKYNET.BE> wrote:
"Gene S. Berkowitz" <first.last@comcast.net> schreef in bericht
news:MPG.1e178d2230f15b2e9896f4@newsgroups.comcast.net...
In article <11qrbnurgr83u82@corp.supernews.com>, rowlett@atlascomm.net
says...
Would not a pilot be interested in exact location of airports and
various beacons? would there be any equivalent of uncharted shoals?
A pilot is not using a consumer-oriented GPS. He is using an aviation
GPS, with a Jeppesen database of beacons, approaches, and airports, that
is maintained via a monthly subscription.
Is he (and/or she)? Each one? Really?
Sure and guaranteed? How can you know?
On my side I HAVE seen pilots fly with "consumer-oriented"
GPS-units, though not as a primary means of navigation, luckily.
And don't come and tell me about "certified" units:
unless I'm much mistaken not any single GPS unit has been certified
by any single European civil aviation authority.
Would you do an approach without much assurance of the GPS satellite
signal quality ? Assuming that the SA would be suddenly switched on
during the approach (or a satellite would experience some sudden
problem), this could have quite serious consequences. For any critical
navigation, you really need some assurance about the signal quality.
A differential-GPS station can constantly verify the signal quality
from all satellites and broadcast this signal quality information to
nearby users (in addition to the differential correction). Without a
DGPS transmitter at every airport, I don't see how you could make a
safe approach with only a GPS receiver.
|
Google "WAAS".
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
|
| Back to top |
|
|
|
|
|
|
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