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On Mon Jun 30 23:16:56 2025 Frank Krygowski wrote:
On 6/30/2025 11:21 AM, Radey Shouman wrote:
Now GPS takes you to the right address andI'd insert "usually" takes you to the right address. I've had GPS and
you're not even aware of the madness.
Google Maps get very confused on occasion, telling me I'd arrived when I
absolutely had not.
Tonight I drove home from a city about an hour away. My car's navigation
system was very upset that I was proceeding on a closed road. But the
road was perfectly fine.
Do you even know how to use Google Maps? Driving from San Leandro to Phoenix, Arizona, not only did it give me explcit directions but I could ask it where the nearest gas station was.
It also has bike routes that can navigate you over bike paths.
And you're saying that it gets confused? I think we all know where the confussion lies.
On Fri Jul 4 04:10:18 2025 Catrike Ryder wrote:
On Thu, 03 Jul 2025 17:52:20 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
On Thu, 03 Jul 2025 17:56:20 -0400, Catrike Ryder
<Soloman@old.bikers.org> wrote:
Well, yes, Jeff. Other people do have other interests, so their needs
are different than mine. I'm not responsible for getting other people
to where they want to go, so why should have any interest in
considering other people's navigation needs?
However, if other people's needs were the same as yours, does that
mean you're not responsible for getting them where they want to go?
You seem to be suggesting that when speaking about something from my
perspective I should also suggest that there are other perspectives. I
guess I just assume people will know that.
That's about as logical as you suggesting that because you're not
interested in some topic, all the other readers of this newsgroup
should be equally disinterested. Yes, I know you didn't say that, but
that's where you're heading.
No, that's not ever where I'm headed.
Why do you expect anyone to listen to
your opinions when you don't care about their interests or their
associated opinions?
Well, actually, I don't have any such expectations.
You really don't need to inform your readers
that you don't care about some topic or activity. Simply not
mentioning that you don't care should be sufficient.
Yes, indeed. There's many things mentioned here on RBT that I don't
address.
I was addressing this issue as a sailor going from port to port.
No, that's not what started this thread. You mentioned in:
This discussion started with references to using GPS for
transportation.
<https://www.novabbs.com/tech/article-flat.php?id=129434&group=rec.bicycles.tech#129434>
No Roger, there aren't any maps out on the ocean because there are no
markers out in the ocean. trust me on this. I've been out there and I
would have seen them.....
There are charts in around land forms where you can have markers. You
could have coordinates out on the ocean and sail towards them, but
maps out on the ocean would be useless.
My main concern is your incorrect claim that "maps out on the ocean
would be useless". They might be useless to you, but as others and I
have demonstrated, there are large numbers of ocean maps which show
features not found on coastline or ocean surface maps. I find these
maps very interesting and sometimes useful. I would be quite happy if
you would simply admit that such maps might be useful to people who do
not limit themselves to using the oceans for highway transportation.
Ok, some people might find mapping the ocean bottom and establishing
coordinates on the surface to be useful.
I'll point out that this discussion began with people addressing GPS
use for transportation, so I guess I erred in assuming that was the
issue.
To be on the safe side, I'll also admit that mapping the "stars" can
be useful, too.
If tranoceanic cables are damaged you use reflection of an electronic signal to tell HOW FAR out on the cable the damage is. Then a ship lifts the cable starting from the nearest port out of the water and if the damage isn't too severe, it is repaired.
Transoceanic communications is radio links between satellites to the surface now and so cables are more or less unnecessary. As usual Liebermann know nothing about what he is talking about and is our Genius in charge of stupidity.
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a
closed road, which absolutely happens in less built up areas, I find that
modern Satnavs cope well with satellite drop outs, and keep with prompts,
back to maps really in urban/suburban areas absolutely maps even free stuff >> like google maps works fine, but not so much once it?s more rural or into
the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite dropped below the horizon.
On Thu Jul 3 20:07:43 2025 John B. wrote:
You are on a voyage out of sight of land (crossing
Atlantic in small sailboat) that will take a number of weeks out of
sight of land and you go through all that?
why not just noon sights and a sextant if you are really fussy.
Because this is nothing more than more lies from Lie bermann.
He couldn't take a simple noon sight if his life depended on it.
Roger, those charts are fairly easy to make since beyond the continental shelf, there is no detail.
And only until you get close to shore do you know latitude and longitude.
So oceanic charts show land masses in their proper spots and shallow water details and the oceans are blue on the charts.
And precisely who cares?
Transoceanic cables used to be necessary for intercontinental communications but now w have communications satellites and cables are falling into disrepair. Unless there is something to hit oceanic charts have no detail. And the transoceanic charts have land masses only accurate for latitude and longitude which are known from original navigational measurements and now GPS.
Catrike and John Slocomb are entirely correct about that and Flunky and Liebermann are doing nothing but showing their ignorance.
On Fri, 04 Jul 2025 18:02:01 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
Roger, those charts are fairly easy to make since beyond the continental shelf, there is no detail.
What kind of detail is missing? Lane lines for fish?
There's actually quite a bit of detail. Most of it was generated with
Sonar, which is far less accurate than aerial LIDAR. If you want
details of the ocean bottom, you need to find a bathymetric map, which
shows water depth in detail.
<https://en.wikipedia.org/wiki/Bathymetry>
Notice the top right map showing the continental shelf.
And only until you get close to shore do you know latitude and longitude.
That's wrong and really amazing. So why do most nautical maps show
lat-long over areas covered with water? If lat-long ends at the
shoreline, the lines would not be needed.
So oceanic charts show land masses in their proper spots and shallow water details and the oceans are blue on the charts.
Wrong again. Paint a map of the world on an inflatable rubber ball to
form a globe. Add some extra air to make the ball larger diameter.
The relative position of the latitude and longitude lines doesn't
change. What does change is the distance between the latitude and
longitude lines. In other words, +30 degrees from the prime meridian
is in the same relative position no matter how large or small the
globe. Another clue is that you can buy globes in a wide variety of >diameters. Despite the changes in diameter, the relative position of >everything on the globe is the same.
You could claim that things are closer together on the ocean bottom
then they are on the surface of the planet. That's true, but does it
really matter? The deepest ocean trench is the Mariana Trench at
11,000 meters deep. The radius of the planet is about 6,363,000
meters. A 100 meter long vessel on the surface. How much would the
vessel shrink if ocean depth was considered in the lat-long
calculations? We have 2 similar right triangles. The larger triangle
has the opposite side equal to 100 meters and base of 3,363,000 meters
(from the ocean surface to the center of the earth). The smaller
triangle has an unknown opposite side, a base of:
3,363,000 - 11,000 = 6,353,000 meters
The included angle is the same for both triangles (similar triangles).
100 / 3,363,000 = X / 6,353,000
X = 99.84 meters.
Therefore the sunken boat has shrunk 0.16 meters or 16 cm.
That's what's commonly known as a trivial amount. Therefore it
doesn't really matter how deep you are in the ocean. The latitude and >longitude lines don't change enough to matter.
And precisely who cares?
And precisely why to is matter if anyone cares or doesn't care? The
math is the same whether you care, or not.
Transoceanic cables used to be necessary for intercontinental communications but now w have communications satellites and cables are falling into disrepair. Unless there is something to hit oceanic charts have no detail. And the transoceanic charts have land masses only accurate for latitude and longitude which are known from original navigational measurements and now GPS.
Catrike and John Slocomb are entirely correct about that and Flunky and Liebermann are doing nothing but showing their ignorance.
Baloney as usual.
On 7/4/2025 1:21 PM, cyclintom wrote:
If tranoceanic cables are damaged you use reflection of an electronic signal to tell HOW FAR out on the cable the damage is.
Then a ship lifts the cable starting from the nearest port out of the water and if the damage isn't too severe, it is repaired.
Transoceanic communications is radio links between satellites to the surface now and so cables are more or less unnecessary. As usual Liebermann know nothing about what he is talking about and is our Genius in charge of stupidity.
Your comment, " ship lifts the cable starting from the
nearest port out of the water" is absolutely ridiculous. No
one in his right mind could believe that.
https://www.onesteppower.com/post/subsea-cable-repair
On Tue Jul 1 12:59:42 2025 Catrike Ryder wrote:
Another undocumented anecdote?
Here's some facts.... A paper map can't tell you where you are and
how far from where you want to be.
I suppose if a person uses his GPS mostly to go out and back on a flat
bike path, he'd find it to be perfectly reliable.
My GPS worked fine in Mexico, Honduras, and all over the Caribbean.
There aren't any maps out on the ocean.
ruse my sexton to measure distance off shore. That was nesessary for
I agree though the early GPS's could be off a mile of two and I would
cyclintom <cyclintom@yahoo.com> wrote:
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a
closed road, which absolutely happens in less built up areas, I find that >>> modern Satnavs cope well with satellite drop outs, and keep with prompts, >>> back to maps really in urban/suburban areas absolutely maps even free stuff >>> like google maps works fine, but not so much once it?s more rural or into >>> the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have
compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite dropped below the horizon.
The 830 will display lost GPS signal or similar wording, but itÆs almost >always due tunnels and so on, the Tom Tom app on the phone car Sat Nav will >make best guess in a similar situation ie display speed and where it
expects you to be now?
Both will display that they have lost GPS signal, so youÆre aware that itÆs >making estimates.
Roger Merriman
On Fri, 04 Jul 2025 18:27:43 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
On Fri, 04 Jul 2025 18:02:01 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
Roger, those charts are fairly easy to make since beyond the continental shelf, there is no detail.
What kind of detail is missing? Lane lines for fish?
There's actually quite a bit of detail. Most of it was generated with >>Sonar, which is far less accurate than aerial LIDAR. If you want
details of the ocean bottom, you need to find a bathymetric map, which >>shows water depth in detail.
<https://en.wikipedia.org/wiki/Bathymetry>
Notice the top right map showing the continental shelf.
And only until you get close to shore do you know latitude and longitude.
That's wrong and really amazing. So why do most nautical maps show >>lat-long over areas covered with water? If lat-long ends at the
shoreline, the lines would not be needed.
So oceanic charts show land masses in their proper spots and shallow water details and the oceans are blue on the charts.
Wrong again. Paint a map of the world on an inflatable rubber ball to
form a globe. Add some extra air to make the ball larger diameter.
The relative position of the latitude and longitude lines doesn't
change. What does change is the distance between the latitude and >>longitude lines. In other words, +30 degrees from the prime meridian
is in the same relative position no matter how large or small the
globe. Another clue is that you can buy globes in a wide variety of >>diameters. Despite the changes in diameter, the relative position of >>everything on the globe is the same.
You could claim that things are closer together on the ocean bottom
then they are on the surface of the planet. That's true, but does it >>really matter? The deepest ocean trench is the Mariana Trench at
11,000 meters deep. The radius of the planet is about 6,363,000
meters. A 100 meter long vessel on the surface. How much would the
vessel shrink if ocean depth was considered in the lat-long
calculations? We have 2 similar right triangles. The larger triangle
has the opposite side equal to 100 meters and base of 3,363,000 meters >>(from the ocean surface to the center of the earth). The smaller
triangle has an unknown opposite side, a base of:
3,363,000 - 11,000 = 6,353,000 meters
The included angle is the same for both triangles (similar triangles).
100 / 3,363,000 = X / 6,353,000
X = 99.84 meters.
Therefore the sunken boat has shrunk 0.16 meters or 16 cm.
That's what's commonly known as a trivial amount. Therefore it
doesn't really matter how deep you are in the ocean. The latitude and >>longitude lines don't change enough to matter.
And precisely who cares?
And precisely why to is matter if anyone cares or doesn't care? The
math is the same whether you care, or not.
Transoceanic cables used to be necessary for intercontinental communications but now w have communications satellites and cables are falling into disrepair. Unless there is something to hit oceanic charts have no detail. And the transoceanic charts have land masses only accurate for latitude and longitude which are known from original navigational measurements and now GPS.
Catrike and John Slocomb are entirely correct about that and Flunky and Liebermann are doing nothing but showing their ignorance.
Baloney as usual.
I'm pretty sure I never claimed that latitude and longitude aren't
sigificant anywhere on the globe.
On Fri, 4 Jul 2025 13:59:48 -0500, AMuzi <am@yellowjersey.org> wrote:
On 7/4/2025 1:21 PM, cyclintom wrote:
If tranoceanic cables are damaged you use reflection of an electronic signal to tell HOW FAR out on the cable the damage is.
It's called a TDR (time domain reflectometer). For long undersea
cables without repeaters, they run two TDR tests, one from each end of
the cable. The location of the break is calculated from the ratio of
the two measured time delays and the known end to end length. For
example, if the end to end length from New York to Scotland is 5,300
km, and the ratio of the two reflected signals was 2:7, the break is
at:
2 / 7 * 5,300 meters = 1,514 meters from the "2" end.
On 7/4/2025 10:36 AM, cyclintom wrote:
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a
closed road, which absolutely happens in less built up areas, I find
that
modern Satnavs cope well with satellite drop outs, and keep with
prompts,
back to maps really in urban/suburban areas absolutely maps even free
stuff
like google maps works fine, but not so much once it?s more rural or
into
the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have
compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite
dropped below the horizon.
https://www.jalopnik.com/three-dead-after-google-maps-directs-driver- off-broken-1851708190/
https://www.sacbee.com/news/nation-world/national/article298122068.html
https://cumberlink.com/news/nation-world/crime-courts/google-maps- lawsuit-north-carolina-death/ article_ad93c842-4b9b-576a-9e7e-58363b91a0e2.html
https://listverse.com/2018/11/27/10-times-gps-failed-with-terrible- consequences/
YMMV, and may very well some day.
I have to wonder about people who feel the need to talk like experts about things he know not the slightest thing about.
On Sun Jun 29 20:05:33 2025 Frank Krygowski wrote:
On 6/29/2025 3:57 PM, cyclintom wrote:
I was a member of two cycling clubs that hade about 40 members total.Only the members of the slow group (beginners and naturally slow riders)
did NOT have a serious injury over the years.
Some things are so much in conflict with all available data that they
are literally unbelievable.
Yes, some people are seriously injured while bicycling. But all the data
I'm aware of tells us that such _serious_ injuries are rare. The study I
just referenced here pointed out that almost all bicycling injuries
reported were "level 1" or mild injuries.
Last I looked, the most common bicycling injuries treated in ER were
abrasions of the lower limbs, i.e. road rash. Second was abrasions of
the upper limbs.
Frank, please stop with your continuous cry of how safe cycling is. Yes it is SAFE but only to a point which you deny. There are some 130,000 injuries that call of hospitalizations every year. A large percentage of these would be prevented by the simple act of wearing a helmet and you deny that.
On 4 Jul 2025 20:27:16 GMT, Roger Merriman <roger@sarlet.com> wrote:
cyclintom <cyclintom@yahoo.com> wrote:
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a >>>> closed road, which absolutely happens in less built up areas, I find that >>>> modern Satnavs cope well with satellite drop outs, and keep with prompts, >>>> back to maps really in urban/suburban areas absolutely maps even free stuff
like google maps works fine, but not so much once it?s more rural or into >>>> the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have
compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite
dropped below the horizon.
The 830 will display lost GPS signal or similar wording, but its almost
always due tunnels and so on, the Tom Tom app on the phone car Sat Nav will >> make best guess in a similar situation ie display speed and where it
expects you to be now?
Both will display that they have lost GPS signal, so youre aware that its
making estimates.
Roger Merriman
The latest greatest GPS receivers now include an inertial navigation
module in addition to all the GPS related gizmos. What's nice about
inertial navigation is that is works where there's no satellite
signals, such as in tunnels, underground garages, under bridges and in
areas shadowed by trees or buildings. When the GPS receiver detects a
loss of signal, the device switches to getting updates from the
inertial navigation model. When the satellite signal returns, it
switches back to using satellite data.
"GPS/INS"
<https://en.wikipedia.org/wiki/GPS/INS>
"VN-200 Rugged GPS-Aided Inertial Navigation System (GPS/INS)" <https://www.navtechgps.com/vn_200_rugged_gps_aided_inertial_navigation_system_gpsins_/>
"GNSS-INS Solutions: IMUs for Inertial Navigation" <https://www.navtechgps.com/departments/inertial-navigation/>
I don't know if Garmin has a product that includes inertial
navigation. I don't think so mostly because of the high cost.
On Fri, 04 Jul 2025 21:37:50 -0400, Catrike Ryder
<Soloman@old.bikers.org> wrote:
On Fri, 04 Jul 2025 18:27:43 -0700, Jeff Liebermann <jeffl@cruzio.com> >>wrote:
On Fri, 04 Jul 2025 18:02:01 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
Roger, those charts are fairly easy to make since beyond the continental shelf, there is no detail.
What kind of detail is missing? Lane lines for fish?
There's actually quite a bit of detail. Most of it was generated with >>>Sonar, which is far less accurate than aerial LIDAR. If you want
details of the ocean bottom, you need to find a bathymetric map, which >>>shows water depth in detail.
<https://en.wikipedia.org/wiki/Bathymetry>
Notice the top right map showing the continental shelf.
And only until you get close to shore do you know latitude and longitude. >>>That's wrong and really amazing. So why do most nautical maps show >>>lat-long over areas covered with water? If lat-long ends at the >>>shoreline, the lines would not be needed.
So oceanic charts show land masses in their proper spots and shallow water details and the oceans are blue on the charts.
Wrong again. Paint a map of the world on an inflatable rubber ball to >>>form a globe. Add some extra air to make the ball larger diameter.
The relative position of the latitude and longitude lines doesn't
change. What does change is the distance between the latitude and >>>longitude lines. In other words, +30 degrees from the prime meridian
is in the same relative position no matter how large or small the
globe. Another clue is that you can buy globes in a wide variety of >>>diameters. Despite the changes in diameter, the relative position of >>>everything on the globe is the same.
You could claim that things are closer together on the ocean bottom
then they are on the surface of the planet. That's true, but does it >>>really matter? The deepest ocean trench is the Mariana Trench at
11,000 meters deep. The radius of the planet is about 6,363,000
meters. A 100 meter long vessel on the surface. How much would the >>>vessel shrink if ocean depth was considered in the lat-long
calculations? We have 2 similar right triangles. The larger triangle >>>has the opposite side equal to 100 meters and base of 3,363,000 meters >>>(from the ocean surface to the center of the earth). The smaller >>>triangle has an unknown opposite side, a base of:
3,363,000 - 11,000 = 6,353,000 meters
The included angle is the same for both triangles (similar triangles).
100 / 3,363,000 = X / 6,353,000
X = 99.84 meters.
Therefore the sunken boat has shrunk 0.16 meters or 16 cm.
That's what's commonly known as a trivial amount. Therefore it
doesn't really matter how deep you are in the ocean. The latitude and >>>longitude lines don't change enough to matter.
And precisely who cares?
And precisely why to is matter if anyone cares or doesn't care? The
math is the same whether you care, or not.
Transoceanic cables used to be necessary for intercontinental communications but now w have communications satellites and cables are falling into disrepair. Unless there is something to hit oceanic charts have no detail. And the transoceanic charts have land masses only accurate for latitude and longitude which are known from original navigational measurements and now GPS.
Catrike and John Slocomb are entirely correct about that and Flunky and Liebermann are doing nothing but showing their ignorance.
Baloney as usual.
I'm pretty sure I never claimed that latitude and longitude aren't >>sigificant anywhere on the globe.
You didn't claim that. Nor did anyone else. I re-read the last few
messages and can't find any mention by anyone that lat-long was >insignificant. If it's important to you, please cut-n-paste the
relevent section where you read that lat-long is not significant and
I'll try to determine what happened.
Jeff Liebermann <jeffl@cruzio.com> wrote:
On 4 Jul 2025 20:27:16 GMT, Roger Merriman <roger@sarlet.com> wrote:Certainly not the xx30 line which I and Tom have which just displays a line >though speed, but the Tom Tom App does appear to keep going but as itÆs on
cyclintom <cyclintom@yahoo.com> wrote:
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a >>>>> closed road, which absolutely happens in less built up areas, I find that >>>>> modern Satnavs cope well with satellite drop outs, and keep with prompts, >>>>> back to maps really in urban/suburban areas absolutely maps even free stuff
like google maps works fine, but not so much once it?s more rural or into >>>>> the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have
compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite
dropped below the horizon.
The 830 will display lost GPS signal or similar wording, but it?s almost >>> always due tunnels and so on, the Tom Tom app on the phone car Sat Nav will >>> make best guess in a similar situation ie display speed and where it
expects you to be now?
Both will display that they have lost GPS signal, so you?re aware that it?s >>> making estimates.
Roger Merriman
The latest greatest GPS receivers now include an inertial navigation
module in addition to all the GPS related gizmos. What's nice about
inertial navigation is that is works where there's no satellite
signals, such as in tunnels, underground garages, under bridges and in
areas shadowed by trees or buildings. When the GPS receiver detects a
loss of signal, the device switches to getting updates from the
inertial navigation model. When the satellite signal returns, it
switches back to using satellite data.
"GPS/INS"
<https://en.wikipedia.org/wiki/GPS/INS>
"VN-200 Rugged GPS-Aided Inertial Navigation System (GPS/INS)"
<https://www.navtechgps.com/vn_200_rugged_gps_aided_inertial_navigation_system_gpsins_/>
"GNSS-INS Solutions: IMUs for Inertial Navigation"
<https://www.navtechgps.com/departments/inertial-navigation/>
I don't know if Garmin has a product that includes inertial
navigation. I don't think so mostly because of the high cost.
a mobile it maybe also able to leverage the transmitter towers?
Roger Merriman
On Fri Jul 4 18:27:43 2025 Jeff Liebermann wrote:
Liebermann, where did you ever do any sailing other than riding over to this country in a ship as a baby?
I providsed a picture of my degree in Commercial Naviation and you're telling me that you know more about it than I do?
I say that the comments of Catrike and John Slocomb are dead on and you're telling us that they aren't and you know better. You do this about everything you know nothing about.
Does it not bother you that they were giving taxpayer money for MediCal to all of the illegals so that YOUR treatments and payments were coming last? ALL of the ER rooms are filled to capacity and your health was endangered. Specialists were not available and you're talking about NAVIGATION? You know nothing about this subject and are avoiding the subjects that are of paramont importance to your life. Why are you doing that?
If you were complaining about the heart damage that most mRNA recipients recieved you would have half of the world agreeing with you. Why does that not seem to matter to you? You woulkd much rather talk all day about things that you're entirely uninformed about. Wake up and smell the roses.
My JOB for 4 years was repairing navigational computers in the Air Force
On Sat, 05 Jul 2025 21:41:07 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
My JOB for 4 years was repairing navigational computers in the Air Force
You claim to have been in the Air Force from May 1961 to some month in
1965.
On Fri Jul 4 18:49:54 2025 John B. wrote:
On Fri, 04 Jul 2025 15:49:00 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
On Tue Jul 1 12:59:42 2025 Catrike Ryder wrote:use my sexton to measure distance off shore. That was nesessary for
Another undocumented anecdote?
Here's some facts.... A paper map can't tell you where you are and
how far from where you want to be.
I suppose if a person uses his GPS mostly to go out and back on a flat >>>>> bike path, he'd find it to be perfectly reliable.
My GPS worked fine in Mexico, Honduras, and all over the Caribbean.
There aren't any maps out on the ocean.
r
I agree though the early GPS's could be off a mile of two and I would
large racing yachts that I was a navigator on.
as a 'sextant" measures angles it is kind of interesting how you used
it to measure distance
John, you can use a sexton to measure the angles between two points and then simply calculate where those two lines cross. Or you can use a sexton to take a noon sight giving you a latitude and a sunrise to give you a longitude
On Sat, 05 Jul 2025 21:41:07 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
My JOB for 4 years was repairing navigational computers in the Air Force
You claim to have been in the Air Force from May 1961 to some month in
1965. By navigation computers, I presume you mean something that flys
in a USAF airplane. Transistors arrived in the late 1950's. The >microprocessor was introduced in the early 1970's. In your time
frame, the technology was either analog, mechanical or tubes.
So, which type of aviation navigation computers were you repairing on
Guam? Lorenz blind landing, mechanical (cams and gears), analog,
Consolan, Omega, Loran A, etc.
"History of computing hardware (1960s - present)" ><https://en.wikipedia.org/wiki/History_of_computing_hardware_(1960s%E2%80%93present)>
On Fri Jul 4 18:49:54 2025 John B. wrote:
On Fri, 04 Jul 2025 15:49:00 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
On Tue Jul 1 12:59:42 2025 Catrike Ryder wrote:use my sexton to measure distance off shore. That was nesessary for
Another undocumented anecdote?
Here's some facts.... A paper map can't tell you where you are and
how far from where you want to be.
I suppose if a person uses his GPS mostly to go out and back on a flat >> >> >bike path, he'd find it to be perfectly reliable.
My GPS worked fine in Mexico, Honduras, and all over the Caribbean.
There aren't any maps out on the ocean.
r
I agree though the early GPS's could be off a mile of two and I would
large racing yachts that I was a navigator on.
as a 'sextant" measures angles it is kind of interesting how you used
it to measure distance
John, you can use a sexton to measure the angles between two points and then simply calculate where those two lines cross. Or you can use a sexton to take a noon sight giving you a latitude and a sunrise to give you a longitude
My use of higher mathmatics and English needed no college course and sticking in any extraneous skilll simply to the that college could make more money is preposterous.
On Sat, 05 Jul 2025 23:05:06 GMT, cyclintom <cyclintom@yahoo.com>imply calculate where those two lines cross. Or you can use a sexton
wrote:
On Fri Jul 4 18:49:54 2025 John B. wrote:
On Fri, 04 Jul 2025 15:49:00 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
On Tue Jul 1 12:59:42 2025 Catrike Ryder wrote:use my sexton to measure distance off shore. That was nesessary for
Another undocumented anecdote?
Here's some facts.... A paper map can't tell you where you are and
how far from where you want to be.
I suppose if a person uses his GPS mostly to go out and back on a flat >>> >> >bike path, he'd find it to be perfectly reliable.
My GPS worked fine in Mexico, Honduras, and all over the Caribbean.
There aren't any maps out on the ocean.
r
I agree though the early GPS's could be off a mile of two and I would
large racing yachts that I was a navigator on.
as a 'sextant" measures angles it is kind of interesting how you used
it to measure distance
John, you can use a sexton to measure the angles between two points and then s
Tom. The instrument is called a "sextant", not a "sexton. These are >sextants:--
<https://www.google.com/search?q=sextant&udm=2>
and this is a sexton:
<https://en.wikipedia.org/wiki/Sexton_(office)>
"A sexton is an officer of a church, congregation, or synagogue
charged with the maintenance of its buildings and/or an associated
cemetery."
Calculating latitude from a noon sight is well known. However, I
didn't know that you could obtain the longitude from sunrise sighting.
How is that done?
Incidentally, taking a sighting near or at the horizon is almost
impossible. Atmospheric diffraction changes the effective size of the
sun. It also blurs the edge of the sun producing a fuzzy reading.
There's no way to view the base (lowest point) of the sun disk at the >horizon, which is likely to be obscured by land, distant clouds, cold
front or most likely, fog. I also couldn't find any altitude
correction tables for apparent altitudes less than about 9 degrees.
Unless I missed something, I don't think it can be done.
On 5 Jul 2025 04:31:16 GMT, Roger Merriman <roger@sarlet.com> wrote:
Jeff Liebermann <jeffl@cruzio.com> wrote:
On 4 Jul 2025 20:27:16 GMT, Roger Merriman <roger@sarlet.com> wrote:Certainly not the xx30 line which I and Tom have which just displays a line >> though speed, but the Tom Tom App does appear to keep going but as its on >> a mobile it maybe also able to leverage the transmitter towers?
cyclintom <cyclintom@yahoo.com> wrote:
On Tue Jul 1 12:09:03 2025 Roger Merriman wrote:
Which is what Frank was talking about! Ie the car sat nav saying it?s a >>>>>> closed road, which absolutely happens in less built up areas, I find that
modern Satnavs cope well with satellite drop outs, and keep with prompts,
back to maps really in urban/suburban areas absolutely maps even free stuff
like google maps works fine, but not so much once it?s more rural or into
the hills where it doesn?t.
That's interesting. How do you tell a Satellite drop out if you have >>>>> compensating softwae? My 1030 has a built in compass and with wheel
sensors I would think that you would never know that a Satellite
dropped below the horizon.
The 830 will display lost GPS signal or similar wording, but it?s almost >>>> always due tunnels and so on, the Tom Tom app on the phone car Sat Nav will
make best guess in a similar situation ie display speed and where it
expects you to be now?
Both will display that they have lost GPS signal, so you?re aware that it?s
making estimates.
Roger Merriman
The latest greatest GPS receivers now include an inertial navigation
module in addition to all the GPS related gizmos. What's nice about
inertial navigation is that is works where there's no satellite
signals, such as in tunnels, underground garages, under bridges and in
areas shadowed by trees or buildings. When the GPS receiver detects a
loss of signal, the device switches to getting updates from the
inertial navigation model. When the satellite signal returns, it
switches back to using satellite data.
"GPS/INS"
<https://en.wikipedia.org/wiki/GPS/INS>
"VN-200 Rugged GPS-Aided Inertial Navigation System (GPS/INS)"
<https://www.navtechgps.com/vn_200_rugged_gps_aided_inertial_navigation_system_gpsins_/>
"GNSS-INS Solutions: IMUs for Inertial Navigation"
<https://www.navtechgps.com/departments/inertial-navigation/>
I don't know if Garmin has a product that includes inertial
navigation. I don't think so mostly because of the high cost.
Roger Merriman
Every GPS will continue generating NEMA 0183 location data for a few
seconds after it moves into a "dead zone". Continuing to generate
live data in really bad locations usually results in random data
points scattered along the approximate track. What the GPS does is
predict where the GPS should be located if the rider continues along
the same track, in the same direction, and in a straight line. Any
positions that are radically outside of a predictable lane (usually
one road width) are discarded.
My ancient Garmin GPS45 and GPS50(?) did not have this feature and
would intermittently deliver erroneous positions all over the planet.
My equally ancient GPS76 had a different algorithm. It had two ways
to measure the speed. One was to calculate the distance between two
adjacent locations using distance divided by time. The other way was
to use Doppler shift from the satellites, which is VERY accurate. If
the two speeds are radically different, then the data is garbage and
is discarded.
Another way to remove garbage data is to calculate how fast the GPS
would need to move to travel from a previous location (or data point).
If the speed is ridiculously high, then it's likely that the current
data point is garbage and should be discarded.
You can easily tell which of these (and other) algorithms are being
used. Go for a ride in a good open location where the streets form a
grid pattern full of 90 degree turns. Ride straight and then make a
90 degree turn. Repeat several times. Record the NEMA 0183 position
reports (GLL or GGA) and plot them with something that will connect
the dots. If every 90 degree turn looks like it overshoots and then
recovers with a half-loop, then it's using some kind of predictive
track algorithm. If the track is a sharp corner, it's using an
algorithm that discards improbably high speeds. If there is a gap at
the corner, which means that a large number of points were discarded,
it's probably discarding points outside of a lane.
The problem is that NONE of the aforementioned methods work if the GPS
moves in anything other than a straight line. If the GPS goes into a
tunnel, and makes a turn while inside the tunnel, there is no way that
the GPS can predict, record or recover such an underground track. This
is why GPS receivers are starting to appear with inertial navigation features. With inertial navigation, it can record movement along any
axis (x,y,z) but with less accuracy than satellite based GPS.
Incidentally, prior to the mass adoption of GPS for vehicle location,
there were navigation systems that were based on 2 axis (x,y) inertial navigation. Basically, they were cost reduced versions of what was
found in submarines and guided missiles. One of these was a system
that measured the rotational speeds of all 4 wheels of a vehicle and
used the numbers to calculate speed and direction. It worked, but it
really hated speed bumps, potholes, and tire skids. R.I.P.
On Fri Jul 4 13:59:48 2025 AMuzi wrote:
Your comment, " ship lifts the cable starting from the
nearest port out of the water" is absolutely ridiculous. No
one in his right mind could believe that.
https://www.onesteppower.com/post/subsea-cable-repair
Andrew, how do you think that you can repair a cable 3,000 meters under water? How do you think that you can even discover where a break is? Electric cables going to or from offshore oil platforms or wind generator are repairable but you have to shut them off and find the failures by using the same technique I explained using radio echos or matching waves. They originally could ONLY be repaired by bringing them to the surface. Now according to one of the pictures in your reference it appears that they now have automation to lift the cable, pump the surrounding area dry and reconnecting the power cables with whatever means that the cable material allows. That seems convenient since they only have to life the cable 10 feet or so since the cables are buried in the bottom setiment.
DATA lines can be repaired robotically but this is fantastically difficult so they use redundancy rather than repair. If the cable is actually broken the repair is very difficult and involves putting this 2 or three foot diameter interface on the ends of the cables which are only a couple of inches in diameter. I expect they have automation for that now but before they simply discarded the cable and replaced it.
I have no idea how you think that past data cables consisting of copper wires were repaired but I personally saw one of the repair ships that would lift the entire cable out of the water with rollers on either end of the ship and set it back down. The ship was very large in order to float the weight of the cable.
On Fri Jul 4 18:43:13 2025 Jeff Liebermann wrote:
On Fri, 4 Jul 2025 13:59:48 -0500, AMuzi <am@yellowjersey.org> wrote:
On 7/4/2025 1:21 PM, cyclintom wrote:
If tranoceanic cables are damaged you use reflection of an electronic signal to tell HOW FAR out on the cable the damage is.
It's called a TDR (time domain reflectometer). For long undersea
cables without repeaters, they run two TDR tests, one from each end of
the cable. The location of the break is calculated from the ratio of
the two measured time delays and the known end to end length. For
example, if the end to end length from New York to Scotland is 5,300
km, and the ratio of the two reflected signals was 2:7, the break is
at:
2 / 7 * 5,300 meters = 1,514 meters from the "2" end.
The reason it's done like this is because it removes all the errors
caused by changes in the cable velocity factor by changes in the speed
of propagation along the cable.
Then a ship lifts the cable starting from the nearest port out of the water and if the damage isn't too severe, it is repaired.
Nope. If they pull on the cable near the shore, it will rip the cable
out of the "cable house" where the cable terminates. There has to be
some drag by the cable on the ocean bottom to prevent such destructive
disassembly.
Transoceanic communications is radio links between satellites to the surface now and so cables are more or less unnecessary. As usual Liebermann know nothing about what he is talking about and is our Genius in charge of stupidity.
Tom. I'm not a genius, but I do know more than you do.
Your comment, " ship lifts the cable starting from the
nearest port out of the water" is absolutely ridiculous. No
one in his right mind could believe that.
https://www.onesteppower.com/post/subsea-cable-repair
Yep.
I noticed that you're so smart that you don't know you only need to measure one end.