Stupid Attorney taling about GPS's

Tarver Engineering wrote:

"Peter" wrote in message
news:ruUYb.349212$xy6.1742195@attbi_s02...

Ron Lee wrote:

"Dave" wrote:



Unaugmented GPS is accurate to within 7.2 meters longitudinally.


Go say that in sci.geo.satellite-nav and see what happens.



Probably not a bad number.

Only if the usual caveats are added; i.e. 95% of the time and assuming the
receiver has good reception conditions. Any attorney trying to discredit
GPS evidence will naturally focus on the 5% of the time when the position
could be off by more than the nominal accuracy and on obstructions,
multi-path reflections, RFI, etc. that can degrade performance,
particularly in a covert installation where the antenna is unlikely to be
optimally placed for good reception.


False.

The convergence of the GPS Jacobian does not occur for the conditions you
describe. One of the major advantages of GPS over current ground based
navigation is the difficulty of spoofing the system.


I suggest you read your "GPS World" issues some more. Improvement of
integrity monitoring was one of the main reasons for requiring augmentation
of GPS. Evidence already presented in this court case also indicates
some of the problems cited above which resulted in momentary errors of
miles rather than meters.
I'm an advocate of GPS navigation but it is not infallible and carries no
absolute 7 m accuracy guarantee.

"Peter" wrote in message
news:0YUYb.349393$xy6.1743180@attbi_s02...
Tarver Engineering wrote:

"Peter" wrote in message
news:ruUYb.349212$xy6.1742195@attbi_s02...

Ron Lee wrote:

"Dave" wrote:



Unaugmented GPS is accurate to within 7.2 meters longitudinally.


Go say that in sci.geo.satellite-nav and see what happens.



Probably not a bad number.

Only if the usual caveats are added; i.e. 95% of the time and assuming
the
receiver has good reception conditions. Any attorney trying to
discredit
GPS evidence will naturally focus on the 5% of the time when the
position
could be off by more than the nominal accuracy and on obstructions,
multi-path reflections, RFI, etc. that can degrade performance,
particularly in a covert installation where the antenna is unlikely to
be
optimally placed for good reception.


False.

The convergence of the GPS Jacobian does not occur for the conditions
you
describe. One of the major advantages of GPS over current ground based
navigation is the difficulty of spoofing the system.


I suggest you read your "GPS World" issues some more. Improvement of
integrity monitoring was one of the main reasons for requiring
augmentation
of GPS.

False.

The failure to monitor the integrity of the WAAS signal is why the test bit
remained set until recently. The integrity issues were WAAS integrity
issues with no relevence to GPS.

Evidence already presented in this court case also indicates
some of the problems cited above which resulted in momentary errors of
miles rather than meters.

A maomentary error with what equipment?

I'm an advocate of GPS navigation but it is not infallible and carries no
absolute 7 m accuracy guarantee.

So far you are zero for two.

But was it TSO'd and permanently installed by a certificated
avionics technician??? If not how could it possibly be at all
accurate????

John Price
CFII/AGI/IGI
http://home.att.net/~jm.price


"Gerald Sylvester" wrote in message
ink.net...


I never read anything about this Scott Petersen murder
trial before. I saw a headline about a "GPS." I started
to read it and I guess the guys car had a GPS in it
and the prosecution is trying to place him at the murder
scene. Well the defense attorney is saying the GPS
is inaccurate due to a malfunction and made the
moronic comment of:
-------------
Peterson's attorney, Mark Geragos, argued that the information gathered
through global positioning system technology was not accurate. GPS uses
signals from dozens of satellites to show a receiver's position to
within a few feet.

"If the FAA will not approve GPS for the landing of an aircraft, how can
a court of law approve its forensic use in a capital case?" he said.
--------------

I don't know if they are approved for auto-landing but
I'm fairly certain it can get me a few hundred feet AGL
on the exact glideslope of an airport 8000 miles away.
I'd generally consider that accurate enough. grin

My handheld GPS-V for my car has lead me to within a few
feet of the front *main* door of places in Amsterdam, Rome,
New York and San Francisco. I'd generally consider that accurate.




Gerald

Tarver Engineering wrote:

"Peter" wrote in message
news:0YUYb.349393$xy6.1743180@attbi_s02...

Tarver Engineering wrote:


"Peter" wrote in message
news:ruUYb.349212$xy6.1742195@attbi_s02...


Ron Lee wrote:


"Dave" wrote:




Unaugmented GPS is accurate to within 7.2 meters longitudinally.


Go say that in sci.geo.satellite-nav and see what happens.



Probably not a bad number.

Only if the usual caveats are added; i.e. 95% of the time and assuming

the

receiver has good reception conditions. Any attorney trying to

discredit

GPS evidence will naturally focus on the 5% of the time when the

position

could be off by more than the nominal accuracy and on obstructions,
multi-path reflections, RFI, etc. that can degrade performance,
particularly in a covert installation where the antenna is unlikely to

be

optimally placed for good reception.


False.

The convergence of the GPS Jacobian does not occur for the conditions

you

describe. One of the major advantages of GPS over current ground based
navigation is the difficulty of spoofing the system.


I suggest you read your "GPS World" issues some more. Improvement of
integrity monitoring was one of the main reasons for requiring

augmentation

of GPS.


False.

The failure to monitor the integrity of the WAAS signal is why the test bit
remained set until recently. The integrity issues were WAAS integrity
issues with no relevence to GPS.

Unaugmented GPS has insufficient integrity monitoring.
http://www.cts.cv.ic.ac.uk/html/Rese...p?seminarID=62
:
"The assessment results also indicated that the current GPS system cannot
meet the RNP in most of the cases and the current integrity monitoring
mechanism is inadequate for providing the necessary integrity monitoring
capability. Therefore, this study suggests that augmentation systems are
needed to support the navigation function for all phases of flight." Jan.
28, 2004, Imperial College, London, Dr. Shaojun.


Evidence already presented in this court case also indicates
some of the problems cited above which resulted in momentary errors of
miles rather than meters.


A maomentary error with what equipment?

Apparent position errors recorded by the monitoring equipment used in the
investigation being discussed.


I'm an advocate of GPS navigation but it is not infallible and carries no
absolute 7 m accuracy guarantee.


So far you are zero for two.

The "Standard Positioning Service Performance Standard," Table 3.6
http://www.navcen.uscg.gov/gps/genin...ndardFINAL.pdf
gives the post-SA specification for horizontal position as being within 13m
95% of the time assuming the receiver can see all signals from satellites
above the horizon. The vertical spec. is 22m, 95% of the time. Actual
performance has exceeded these specifications but AFAIK the specification
has not been updated.
Feel free to cite any GPS specification that guarantees 7 m accuracy 100%
of the time regardless of reception conditions.

He had to pardon all his buddy criminals (like Mr. Rich, etc)

"Morgans" wrote in message
...

" jls" wrote

However, if an attorney gives
materially false testimony while under oath he is also guilty of
perjury,
ordinarily a felony.

Unless your name is Bill Clinton. I still can't believe we didn't throw
that clown out on his ear, then throw him in jail. Now, unless you stick
yur "dickie" in someone, it isn't sex. Jeeesh .
--
Jim in NC


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.580 / Virus Database: 367 - Release Date: 2/6/04

Huh,

I was under the impression that the GPS signals are fairly weak and
intentional interference is a serious issue.
Is that not correct?

Can you provide some sources for your statements?

thanks

"Tarver Engineering" wrote in message
...

"Peter" wrote in message
news:ruUYb.349212$xy6.1742195@attbi_s02...
Ron Lee wrote:
"Dave" wrote:


Unaugmented GPS is accurate to within 7.2 meters longitudinally.


Go say that in sci.geo.satellite-nav and see what happens.



Probably not a bad number.

Only if the usual caveats are added; i.e. 95% of the time and assuming
the
receiver has good reception conditions. Any attorney trying to
discredit
GPS evidence will naturally focus on the 5% of the time when the
position
could be off by more than the nominal accuracy and on obstructions,
multi-path reflections, RFI, etc. that can degrade performance,
particularly in a covert installation where the antenna is unlikely to
be
optimally placed for good reception.

False.

The convergence of the GPS Jacobian does not occur for the conditions you
describe. One of the major advantages of GPS over current ground based
navigation is the difficulty of spoofing the system.

On Wed, 18 Feb 2004 14:52:39 GMT, Gerald Sylvester
wrote:

I never read anything about this Scott Petersen murder
trial before. I saw a headline about a "GPS." I started
to read it and I guess the guys car had a GPS in it
and the prosecution is trying to place him at the murder
scene. Well the defense attorney is saying the GPS
is inaccurate due to a malfunction and made the
moronic comment of:
-------------
Peterson's attorney, Mark Geragos, argued that the information gathered
through global positioning system technology was not accurate. GPS uses
signals from dozens of satellites to show a receiver's position to
within a few feet.

"If the FAA will not approve GPS for the landing of an aircraft, how can
a court of law approve its forensic use in a capital case?" he said.
--------------

Since the original report, there has been a second news release after the
defense got the actual records from the prosecution. In several instances, the
GPS readings had Peterson's truck at two different locations hundreds of miles
apart in 6 or 7 minutes, at an equivalent ground speed of something like 260
mph. The errors occurred often enough that the defense thought they ought to
challenge all of the GPS data. Another problem was the GPS transmitted
constantly to the police through cell phone connections which may have distorted
the data.

All the proceeding comments were taken from TV media reports, so take their
accuracy with a grain of salt.

Ron

On 18 Feb 2004 18:56:17 GMT ackatyu (Wdtabor) wrote:

In article 20040218083913.322b40c6@fstop, "R.Hubbell"
writes:


"If the FAA will not approve GPS for the landing of an aircraft, how can
a court of law approve its forensic use in a capital case?" he said.


The technique is known as "casting a shadow of doubt". It works
wonderfully well. Jurors eat it up. He's doing his job.


I would think he would be questioning what business the police had tracking
Peterson's whereabouts AFTER the crime was commited.

Not following the trial but....
What's wrong with that? It's common for them to watch someone. What they
do can speak volumes even if it is not admissable it might lead them to
something else.

The defense should just keep casting doubts. Those doubts will stick in the
jurors' craw.



It seems the prosecution is trying him with character assasination after the
fact rather than with evidence of the crime itself. He'll probably wind up
being the first person executed for having an affair.

The guy has been tried in the media and found guilty. A lot of what they have
sounds circumstantial. There are a few twists to the case that are unusual.

His name was on a list of suspects that the police talked to about a missing
co-ed while he was at college.

There have been other cases of pregnant women that were killed and have
not had much attention at all.



R. Hubbell


Don

--
Wm. Donald (Don) Tabor Jr., DDS
PP-ASEL
Chesapeake, VA - CPK, PVG

On Wed, 18 Feb 2004 14:52:39 GMT, Gerald Sylvester
wrote:

Peterson's attorney, Mark Geragos, argued that the information gathered
through global positioning system technology was not accurate. GPS uses
signals from dozens of satellites to show a receiver's position to
within a few feet.

"If the FAA will not approve GPS for the landing of an aircraft, how can
a court of law approve its forensic use in a capital case?" he said.

Well, that's how a defense attorney earns his cat food. I rather liked
the quote

(Note that the bit about "dozens of satellites" was almost certainly
written by the reporter, and is not a quote from the lawyer.)
all the best -- Dan Ford
email:

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

On Wed, 18 Feb 2004 07:33:31 -0800, "Tarver Engineering"
wrote:

At that point Scott's Attorney would be well on
his way to giving testimony illegally.

The lawyer wasn't giving testimony! He can say any damn thing he
pleases, subject to being shut up by the judge.

Sheez. You're on this newsgroup, too?

all the best -- Dan Ford
email:

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com