Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:


That should have been:

Are you seriously suggesting that animals and birds don't know where
they are because they don't go around reading maps?

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 7 Oct 2026 09:45:48 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

That should have been:

Are you seriously suggesting that animals and birds don't know where
they are because they don't go around reading maps?

Animals can probably recognize surface topologies like people can
recognize faces. Some of the Ukranian drones use topological
navigation when their GPS is jammed.


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Subject: GNSS (was: 97-million-year-old fossils reveal the earliest known animal "GPS")

Old McDonald wrote:

On 10/2/26 08:46, Bill Sloman wrote:

You've got to be able to receive signals from at least four satellites
at the same time to be able to work out where you (and you can do it
pretty precisely).

Well, you gave us an incomplete sentence, "...to be able to work out
where you..." so nobody can be sure what you're talking about.

Four satellites needed for navigation, three satellites for position.

False. There are _4 unknowns_ in the GPS/GNSS navigation equation which
is basically the Minkowski metric for light: the 3 spatial coordinates
of the receiver _and_ its clock bias (the time of reception is known,
and the time of transmission is known from the satellite's signal, from
which also the satellite's position can be determined via its ). As a
result, at least _4 equations_ are required to solve a system of
navigation equations; therefore, _4 satellites_ have to be in the
line-of-sight of a GNSS receiver (i.e. above its local horizon if it is
on the surface) for it to calculate its position; the number of GPS
satellites (about 80 are currently operating) and their orbits make sure
that this is the case for every GPS receiver on the surface at all times.

In addition to that, GPS is augmented by other GNSS constellations like
GLONASS and Galileo which are supported by many receivers (certainly in smartphones). China also has its own locally available GNSS, BeiDou.

You can test that on your mobile device by using the app "GPS Test", for example.

https://en.wikipedia.org/wiki/Global_Positioning_System

Read that more carefully.

GPS requires four or more satellites to be visible for accurate navigation.

You do not know what you are talking about. The receiver's determining
its own position is _a prerequisite_ for using it for navigation,
because navigation means that the path to the designated destination
needs to be discovered, and the receiver's position changes; it is not
possible to determine whether the receiver's follows the discovered path
or has reached the destination without determining its position.

Note that "GPS" is used in the Subject and the referred article in double-quotes, i.e. _figurately_ only.

F'up2 sci.physics

--
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 10/7/26 10:48, Thomas 'PointedEars' Lahn wrote:

Old McDonald wrote:

On 10/2/26 08:46, Bill Sloman wrote:

You've got to be able to receive signals from at least four satellites
at the same time to be able to work out where you (and you can do it
pretty precisely).

Well, you gave us an incomplete sentence, "...to be able to work out
where you..." so nobody can be sure what you're talking about.

Four satellites needed for navigation, three satellites for position.

False. There are _4 unknowns_ in the GPS/GNSS navigation equation which
is basically the Minkowski metric for light: the 3 spatial coordinates
of the receiver _and_ its clock bias (the time of reception is known,
and the time of transmission is known from the satellite's signal, from
which also the satellite's position can be determined via its ). As a result, at least _4 equations_ are required to solve a system of
navigation equations; therefore, _4 satellites_ have to be in the line-of-sight of a GNSS receiver (i.e. above its local horizon if it is
on the surface) for it to calculate its position; the number of GPS satellites (about 80 are currently operating) and their orbits make sure
that this is the case for every GPS receiver on the surface at all times.

In addition to that, GPS is augmented by other GNSS constellations like GLONASS and Galileo which are supported by many receivers (certainly in smartphones). China also has its own locally available GNSS, BeiDou.

You can test that on your mobile device by using the app "GPS Test", for example.

https://en.wikipedia.org/wiki/Global_Positioning_System

Read that more carefully.

I already read it, and quoted from it, and posted the same link to it.

"GPS requires four or more satellites to be visible for accurate
navigation."

"There are marked performance benefits to the user carrying a clock synchronized with the satellites. Foremost is that only three satellites
are needed to compute a position solution."

"Although four satellites are required for normal operation, fewer apply
in special cases. If one variable is already known, a receiver can
determine its position using only three satellites. For example, a ship
on the open ocean usually has a known elevation close to 0 m, and the elevation of an aircraft may be known."

GPS requires four or more satellites to be visible for accurate navigation.

You do not know what you are talking about.

You snipped everything that I quoted from wikipedia. Go read it more
carefully yourself.

The receiver's determiningits own position is _a prerequisite_ for using it for navigation,
because navigation means that the path to the designated destination
needs to be discovered, and the receiver's position changes; it is not possible to determine whether the receiver's follows the discovered path
or has reached the destination without determining its position.

Note that "GPS" is used in the Subject and the referred article in double-quotes, i.e. _figurately_ only.

F'up2 sci.physics

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Old McDonald wrote:

On 10/7/26 10:48, Thomas 'PointedEars' Lahn wrote:

Old McDonald wrote:

https://en.wikipedia.org/wiki/Global_Positioning_System

Read that more carefully.

I already read it, and quoted from it, and posted the same link to it.

You did not indicate that you quoted from it.

"GPS requires four or more satellites to be visible for accurate navigation."

That is what I said.

"There are marked performance benefits to the user carrying a clock synchronized with the satellites. Foremost is that only three satellites
are needed to compute a position solution."

This claim has been tagged "[citation needed]".

"Although four satellites are required for normal operation, fewer apply
in special cases. If one variable is already known, a receiver can
determine its position using only three satellites. For example, a ship
on the open ocean usually has a known elevation close to 0 m, and the elevation of an aircraft may be known."

This claim is missing a citation, and a caveat is added in the footnote
"[a]".

I will check those claims for feasibility later, when I have the time.

F'up2 sci.physics again. When will you stop amok-crossposting?

--
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)