While GPS, GLONASS and Galileo — mainly act as beacons, beaming out 1-way signals, BeiDou is a 2-way communication system, allowing it to identify the locations of receivers. It has better worldwide coverage, more
satellites available to compute locations than GPS and better coverage of
low latitudes. BeiDou satellites uses utilizes hydrogen atomic clock with the
stability of E-15 and rubidium clock with E-14 stability, compatible with BIMP
UTC/TAI. The system uses Chinas own reference coordinates instead of ECI.

Such a capability has raised serious security concerns. "All cellular devices, as I understand their function, can be tracked because they continually communicate with towers or satellites," Dr. Larry Wortzel, a commissioner of the U.S.-China Economic and Security Review Commission (USCC), told VOA.

The Taiwan Strait Crisis of 1996 prompted Beijing to build its global
navigation and positioning satellite system, avoiding its prior use of
GPS for military applications. The American military says it uses Russian
and European backup systems for GPS, but not BeiDou.

Officially started in 1994, BeiDou is consistently referenced as "the
biggest" aerospace program that China ever undertaken. For the past 2½
years alone, there have been more than 300,000 scientists and engineers
from more than 400 research institutions and corporations involved in the
program. Along with 5G, BeiDou is called by Beijing "The Two Pillars of a
Great Power.”

http://en.beidou.gov.cn/

The BDS is mainly comprised of three segments: space segment, ground
segment and user segment.

– The space segment. The BDS space segment is a hybrid navigation
constellation consisting of GEO, IGSO and MEO satellites.

* 5 geostationary orbit satellites.
* 27 in medium Earth orbit, Medium Earth Orbit (MEO) .
* 3 in inclined geosynchronous orbit, Inclined GeoSynchronous
Orbit (IGSO).

– The ground segment. The BDS ground segment consists of various
ground stations, including master control stations, time synchronization/
uplink stations, and monitoring stations. One master control station is
located in Argentina (south western site).

– The user segment. The BDS user segment consists of various kinds
of BDS basic products, including chips, modules and antennae, as well as
terminals, application systems and application services, which are
compatible with other systems.

The BDS possesses the following characteristics: First, its space segment
is a hybrid constellation consisting of satellites in three kinds of orbits..

In comparison with other navigation satellite systems, the BDS operates
more satellites in high orbits to offer better anti-shielding capabilities,
which is particularly observable in terms of performance in the low-
latitude areas. Second, the BDS provides navigation signals of multiple
frequencies, and is able to improve service accuracy by using combined
multi-frequency signals. Third, the BDS integrates navigation and
communication capabilities for the first time, and has five major functions:
real-time navigation, rapid positioning, precise timing, location reporting
and short message communication services.

The ratification of the BDS by international standards is a milestone
for the integration of the BDS into international systems. China spares no
effort to get the BDS ratified by the International Organization for
Standardization and other international organizations in the industrial and
professional application sectors.

All BeiDou satellites are equipped with laser retroreflector arrays for Satellite Laser Ranging[53] and the verification of the orbit quality.[

The free civilian service has a 10-metre location-tracking accuracy,
synchronizes clocks with an accuracy of 10 nanoseconds,
and measures speeds to within 0.2 m/s. The restricted military service has a
location accuracy of 10 centimetre, can be used for communication (SMS services), and will supply information about the system status to the user.

On Friday, October 22, 2021 at 10:08:07 PM UTC-5, Richard Hertz wrote:
> While GPS, GLONASS and Galileo — mainly act as beacons, beaming out 1-way signals,
> BeiDou is a 2-way communication system, allowing it to identify the locations of receivers.

You are getting the original Beidou-1 (which has been decommissioned)
and Beidou-2 mixed up.

Beidou-1 used a two-way protocol that not require orbiting atomic clocks.
Portable transceivers communicated with nearby ground stations (which
typically would have been trucked into a region that required accurate
positioning), which in turn communicated with geostationary satellites.
From the two-way time delays between receiver, ground stations, and
satellites, the transceiver position could be computed. The requirement for
two-way communication meant that the number of transceivers that could
simultaneously be supported was *severely* limited. Early transceivers were
quite bulky. I remember seeing a photo of a young Chinese infantryman
carrying a Beidou-1 transceiver in a backpack with the send/receive
antenna sticking up out of the top of the pack, and I didn't want to guess
how much EM radiation was blasting through his skull...

The current Beidou-2 (also known as COMPASS) uses technology more in
line with other GNSS systems.

On 10/22/2021 11:08 PM, Richard Hertz wrote:
>
> While GPS, GLONASS and Galileo — mainly act as beacons, beaming out 1-way signals, BeiDou is a 2-way communication system, allowing it to identify the locations of receivers.

Beidou-1, the two-way system is OBSOLETE and decommissioned. Beidou-2
is similar to all the other GNSS systems. I guess there is a Beidou-3 now.

<snip rest of blithering>

Nowhere do you support your claim in the subject that Beidou doesn't use
relativity. Which is good, since, if true, that would mean one of
several things:

1) Relativity works for everyone else but not for China. The first
postulate is thus wrong.
2) Beidou-2 is very error-prone, being off by about 10 km/day.
3) Beidou satellites orbit at the exact altitude (about 3200 km) where
the velocity and gravitational effects of GR exactly cancel.

On Saturday, October 23, 2021 at 9:15:56 AM UTC-7, Michael Moroney wrote:
> On 10/22/2021 11:08 PM, Richard Hertz wrote:
> >
> > While GPS, GLONASS and Galileo — mainly act as beacons, beaming out 1-way signals, BeiDou is a 2-way communication system, allowing it to identify the locations of receivers.
> Beidou-1, the two-way system is OBSOLETE and decommissioned. Beidou-2
> is similar to all the other GNSS systems. I guess there is a Beidou-3 now..
>
> <snip rest of blithering>
>
> Nowhere do you support your claim in the subject that Beidou doesn't use
> relativity. Which is good, since, if true, that would mean one of
> several things:
>
> 1) Relativity works for everyone else but not for China. The first
> postulate is thus wrong.
> 2) Beidou-2 is very error-prone, being off by about 10 km/day.
> 3) Beidou satellites orbit at the exact altitude (about 3200 km) where
> the velocity and gravitational effects of GR exactly cancel.

Every day, several times a day, Richard Hertz offers proofs (multiple) of his imbecility. This is what makes him the most entertaining crank in this forum.

On Saturday, 23 October 2021 at 18:15:56 UTC+2, Michael Moroney wrote:
> On 10/22/2021 11:08 PM, Richard Hertz wrote:
> >
> > While GPS, GLONASS and Galileo — mainly act as beacons, beaming out 1-way signals, BeiDou is a 2-way communication system, allowing it to identify the locations of receivers.
> Beidou-1, the two-way system is OBSOLETE and decommissioned. Beidou-2
> is similar to all the other GNSS systems. I guess there is a Beidou-3 now..
>
> <snip rest of blithering>
>
> Nowhere do you support your claim in the subject that Beidou doesn't use
> relativity. Which is good, since, if true, that would mean one of
> several things:
>
> 1) Relativity works for everyone else but not for China.

Relativity works only in sick imagination of some
brainwashed halfbrains; in the meantime in the real
world - GPS clocks keep measuring t'=t, just like
all serious clocks always did.