GPS World: USNO's Fountain: Time at 100 Trillionths of a Second

Sammy,
I suggest that if you spent more time and thought on messages
and less time on messengers,

that you would learn something about physics and the GPS system,
and be able to discuss these issues in the newsgroups.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

Do newsgroup searches on
"Galileo Effect", Hubble Effect and the Doppler Effect
and you will have your answer.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

It is interesting to see that Y.Porat
asserts that "irrational racist opposition"
and "a pathological hatred for Jews"

motivates "Potter" and perhaps other folks to object to
Time Magazine, the New York Times, and the Washington Post
naming Einstein as "The Man of the Century"

and his General Relativity
as mankind's greatest scientific achievement.

It is helpful to compare General Relativity to
some other science models.

After Newton's model,
there were immediate and rapid advances
in mechanics, astronomy, etc.

After Maxwell's model
there were immediate and rapid advances
in chemistry, electricity, etc.

After Watson's and Crick's DNA model
there were immediate and rapid advances
in medicine, genetics, animal husbandry,
the history of the Earth and Mankind, etc.

I noticed in the news recently
that the DNA model was recently used to develop
a new form of rice that will prevent 500,000 children
from going blind EVERY YEAR,

and that it was used to convert blood types,
and that people with rare blood types will have a safe
supply of blood in the future,

and I also noticed recently
that the DNA model was used to discover
that chickens are related genetically to the dinosaur.

The question is
what is a greater scientific achievement,

a model that wastes time, money and minds
on things that are useless, non-cost-effective,
or far, far beyond man's capacity to
experience in time and space,

things like the birth and death of the universe,
time travel, warping through space, worm holes,
black holes, gravitons, evolution of stars, etc.

or an achievement like DNA that is used
to develop better food crops,
improve animal husbandry,
develop better medicine,
reconstruct history more accurately,
cure cancer,
create bees that pollinate essential plants more surely,
create animals that can sniff out chemicals and diseases, etc.,
save endangered animals,
find criminals,
purify water,
etc.

It seems to me, that the people
at Time Magazine, the New York Times, and the Washington Post
who named Einstein as "The Man of the Century"
are the real racists,

not the folks who object to Jewish controlled media
making Einstein the Poster Boy for Jewish intelligence.

A mind is a terrible thing to waste.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

One wonders how the GPS receiver would acquire
o accurate up2date orbital elements for the satellites
o accurate time
o knowledge of satellite replacement, orbital changes, health, etc.

One wonders if Potter has any technical education.

 

Although he did not seem to have read
or at least comprehend my post.
I am pleased to see that Sam Wormley
is interested in learning more about
advanced navigation systems.

As I mentioned, as the time and satellite data
transmitted by the GPS System cannot be completely trusted
during times of strife because the American military may play
games with the system, or adversaries such as
Russia, Israel, Iran, etc. may activate software bombs
planted in the system,

a simpler, less complex and cheaper GPS System could
be designed around using the orbits of the satellites
as the basic clocks, and GPS receivers could mark
orbits by detecting zero beats as each satellite passed overhead.

I suggest that a better system
would maintain satellite and atmospheric data
on various COMMERCIAL web sites,
and that the data could be downloaded by
cell phone, or by accessing the web,
and loading the data into a flash memory card
which could be inserted into the GPS receiver.

To avoid a cold start, a "cell phone" feature
could be incorporated into the receivers to
access a COMMERCIAL web site,
advise the site of the cell phone tower location,
and download the best data for that location,
to get the receiver going quickly.

And considering that frequently government employees
are asleep at the switch, the data could be reviewed
and massaged, much like Wikipedia data,
to provide users with the option of accepting or rejecting
corrections to the government data.

Also, if the GPS software were open architecture,
user groups could upload better algorithms to
compensate for variations in atmospheric conditions and such.

As I mentioned, the most stable and dependable data
is the actual orbits of the satellites, as it is difficult to
change the orbit of a satellite and limited amounts of fuel are
available to change the orbits,

and a GPS receiver could be designed and programmed
to detect in phase and quadrature zero beats
as the satellites passed overhead,
and use this data to verify that the system data is valid,
and to update the receivers satellite data,
if it is not.

The receiver could start a counter at each zero beat,
and use an ordinary crystal oscillator to trace out the orbit
of each satellite.

For example, as a GPS satellite orbits the Earth in about 12 hours,
a 13 MHz signal driving frequency counters in the receiver
would mark off 10 foot steps for each satellite,
referenced to the Earth's surface.

The bottom line is,
that the ACTUAL orbits of the satellites are more dependable
indicators of WHERE each satellite is,
than massaged and uploaded data
from unreliable and untrustworthy sources.

I would like to thank Sammy
for his continuing interest in my posts,
and I will be looking forward to explaining more
about physics and navigation systems to him.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

Considering that Sam Wormley does not address posts
in an honest way, but edits and distorts them,
I am reposting the original post.

Sammy is right when he notes that
"relativistic effects were not observed by Galileo"

Galileo, with his original and creative experiments
OBSERVING the EFFECTS
of time, acceleration, velocity, forces
celestial motions, etc. was a clear thinker,
and provided the stimulus for the rapid advancement of physics.

On the other hand, by trying to extend
the model (Stresses and strains) and methods (Tensors)
of the stress analysis engineers, to model
structures inhabited by sentient beings,

Einstein created an auguring system that introduced babble
into physics with such concepts as rubber clocks and rulers,
time travel, worm holes, space warps,
the beginning and end of the universe, etc.

eliminated sentient man from the universe,

inhibited the advancement of science,

and wasted time, money and minds.

The fact of the matter is that NO ONE has ever
observed "relativistic effects".

What people have observed are effects first noted
by people like Galileo (Acceleration effect),
Doppler (Velocity effect), Hubble (Distance effect), etc.

Sammy, like most people, has been conditioned
by the mass media to steal credit from thousands
of hard-working, creative folks,
and attribute the work to the Media's Poster Boy
for Jewish intelligence, by obfuscating the original work,
lumping it all together under the generic term "relativistic effects".

And as can be seen by his parroting, personal attacks,
and his reluctance to come to grips with the
physical aspects of the GPS System,
Sammy does not understand the system,

and is reluctance to give credit where credit is due
for making the GPS System a reality. Rocket technology,
integrated circuits, microprocessor technology,
information theory and digital communications technology,

and of course, the giants upon whose shoulders
today's creative engineers stand:
Galileo, Newton, Faraday, Maxwell, Doppler, Edison, etc.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

Pathetic Potter Panders Perpetually.

Bluster on, Potter, bluster some more! Froth at the mouth! Whatever!

 

GPS has basically two functions
o Navigation signals
o Nuclear detection

L1 1575.4200 Civil/Military Frequency
L2 1227.6000 Civil/Military Frequency
L3 1381.0500 Nuclear Burst Detection
L4 1841.4000 Ionospheric correction (proposed)
L5 1176.4500 Civil/Military Frequency


There are currently three frequencies used and a fourth (L5)
beginning in 2009.

L5 L2 L3 L1 L4
------------+-------+-----------|---------------------------+--------------+----
1176.45 1227.60 1381.05 1575.42 MHz 1841.40
115 x 120 x 135 x 154 x 10.23 MHz 180 x
| | | |
| | | |
Current | | | C/A
Signals | P(Y) NUDET P(Y)
| | |
| | |
| | |
Proposed P-like C/A(Possibly P-like code) C/A
New Signal code P(Y) P(Y)
Structure M-Codes M-Codes


Note that the military and other authorized users have access to
the Y-code at the chip rate of 10.23 Mbps. Course Acquisition (C/A)
is at a chip rate of 1.023 Mbps. However, since the unknown Y-code
is identical on both L1 and L2, several techniques can be used to
extract the 10.23 MHz carrier information, which is used in high
accuracy differential receivers (surveying).


Technique SNR loss**
---------------------------------------------------------
Squaring -30 dB
Cross correlation -27 dB
Code correlation plus squaring -17 dB
Z-Tracking (reported by Ashjaee and Lorenze 1992) -14 dB

**Loss compared to direct code correlation as used on
military dual frequency receivers.




L1 and L2 Navigation satellite Signal Power Budget

Parameter L1 P-Code L1 C/A-Code L2 P-Code
-----------------------------------------------------------------------
User minimum received power -163.0 dBw -160.0 dBw -166.0 dBw
Users linear antenna gain 3.0 dB 3.0 dB 3.0 dB
Free-space propagation loss 184.4 dB 184.4 dB 182.3 dB
Total atmospheric loss 2.0 dB 2.0 dB 2.0 dB
Polarization mismatch loss 3.4 dB 3.4 dB 4.4 dB
Required satellite EIRP +23.8 dBw +26.8 dBw +19.7 dBw
Satellite Antenna gain at 14.3? 13.5 dB 13.4 dB 11.5 dB
worst case Block II off-axis angle
Required minimum satellite antenna +10.3 dBw +13.4 dBw +8.2 dBw
input power 10.72W 21.88W 6.61W




Of course all the new signals are being implemented at this time and the
signal structures for GPS and Galileo are complex. My old links to the
articles have broken... which implies to me that the information is now
incorrect... when I re-run across a current spectral chart, I'll do a
follow up posting.

____________________________________________




CNAV Messages on GPS L2 to Begin in Fall 2009
http://mg.gpsworld.com/gpsmg/content/printContentPopup.jsp?id=562790

Nov 3, 2008
GPS World

In the fall of 2009 GPS operators at the U.S. Air Force's 50th Space Wing and the 2nd
Space Operations Squadron will upload software to the IIR-M satellites enabling the first
broadcast of a transitional civil navigation (CNAV) message on the already transmitted
second civil signal (L2C).

With the upcoming launches of the remaining two IIR-Ms, there will be a total of eight
modernized GPS satellites broadcasting on the L2C frequency (1227.60 MHz) with the new
CNAV message. GPS IIF satellites will also be launched with the built-in capability to
broadcast the new message.

The modernized L2C signal was designed with several significant advantages over the
existing L1 signal, according to the Air Force. It will provide a lower tracking threshold
and better cross-correlation protection. Furthermore, the data portion of the L2C signal
is also different; instead of the current structure with subframes of data repeating in a
fixed pattern as on L1, the CNAV structure which will be used on L2C has individual
messages which can be broadcast in a flexible order with variable repeat cycles.

The CNAV structure, as defined in Interface Specification (IS)-GPS-200D, allows up to 63
different message types, of which 15 types have already been defined, the Air Force said.
The 15 CNAV message types will be incrementally phased in over time, with the first CNAV
message to broadcast being the default message, also known as Message Type 0. Message Type
0 consists of a 12-second, 300-bit long message including the preamble, satellite
pseudorandom noise (PRN) number, message type ID (=0), GPS time of week, a sequence of
alternating 1s and 0s, and a cyclic redundancy check (CRC) parity block. The GPS time of
week will change every 12 seconds, as will the CRC bits.

Eventually a third civil signal will be added centered at the L5 frequency (1176.45 MHz),
as well as M-Code signals on L1 and L2, will be added as part of the GPS modernization
program. L5 will also carry CNAV messages and will broadcast from IIF and the GPS III
satellites.

 

In today’s technology, it is still tremendously difficult to extract a
clock accurate down to a few tens of nanoseconds based on each
satellite’s own orbit. It is a clever idea but not very achievable
today. Thanks for this suggestion to challenge our next generations
of engineers.

 

So, where are these relativistic corrections necessary in L3, L4, and
L5 after we have already established that L1 and L2 which covers
almost all the applications of GPS do not require any relativistic
corrections?

 

It is a challenge - that's why it isn't done that way.

 

<< So, this is the second time that Sam shows his unsportsmanlike
conduct
by opting out of answering my fair questions. >>

Sums getting a bit rusty, KW?
BCD Arithmetic, a tutorial
http://www.cs.uiowa.edu/~jones/bcd/bcd.html

Sam was the Bush administration's "private sector"
and "faith based" attempt at selective availability.
He disseminates crap to the civilian users to degrade
the accuracy so the system can't be used for targeting.

The password to shut Sam off was lost when a box
of embarrassing emails was smuggled out of USNO
in a wheelchair a few weeks ago. )

Sue...

 

What makes you think those carriers frequencies are not derive from
the same satellite clock Koobee?

 

As can be seen from the Wikipedia article quoted below,
crystals are normally cut so that they perform best at room temperature,
and will operate over a reasonable temperature range.

http://en.wikipedia.org/wiki/Crystal_oscillator

A good temperature compensated crystal will perform pretty good,
and probably provide accuracies of about 100 feet,
and even better if the clock driven by the oscillator
is updated each time the receiver obtains a zero beat
from a satellite.

As there are 24 satellites, and they make two passes per day,
the system should detect enough zero beats to keep the receiver
on track. And Google Earth, cell phone towers or manual data entry
could be used establish calibration points on the Earth's surface.
( Many times only relative position is needed.)

As it is difficult to match up the temperature characteristics of
a quartz crystal and a themistor,

if I designed a system like this,
I would have the crystals cut to perform best at
the freezing point of water, and
have the crystal located in a tiny thermocooler
that maintained an ice bath at freezing,
something like the patent described at the URL below.

http://www.google.com/patents?id=BxBFAAAAEBAJ&dq=3027725

The attractive feature of a system like this,
is that it would operate if the ground stations were taken out.

You are right that it would be hard to make a salable system like this,
but the point I was trying to make,
is that there are more ways than one to skin a cat.

--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm

 

Perhaps you didn't get enough sleep Dennis Sue!
http://pnt.gov/public/sa/

 

Correction for relativistic time dilation makes time synchronization
much easier, Koobee.

 

Are there temperature ranges where frequency change and a function
of temperature in minimized?

Potter should put a number to "perform pretty good" and calculate
position accuracy in feet instead of guessing!

I counted 31 active GPS satellites just now. I don't know
about passes, as some barely clear the horizon, but those
birds are in half sidereal day orbits.

Beats of what against what Potter. Could you be thinking
L1 CA carrier frequency against a synthesized clock in a
GPS receiver?


And Google Earth, cell phone towers or manual data entry

If there are a sufficient density of enabled cell towers in
the area, position can be determined to about 125 feet of actual
position.

Relative with respect to what?

Yes it is.

What do you mean by "perform best". Are there temperature
ranges where frequency change and a function of temperature
in minimized?

Similar to an oven.

Atomic clocks are more stable by orders of magnitude than
temperature controlled crystal. Where have you been, Potter?

I'd like to see any other skinned cat perform as well as our
relativistically compensated satellite based atomic clocks.

 

Quartz Crystals in a satellite?

hahaha...good joke.

Here, have a look at the actual GPS satellite clocks:

http://www.spectratime.com/

Hint: look at the offset ranges provided on the rubidium tickers,
what do you think why there is such a big offset range necessary?

w.