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Included
in this Newsletter:
(click on hyperlinks below to jump to news items)
1)
Get Ready for ION GPS-2002! IT'S JUST 9 WEEKS AWAY!
2)
GALILEO Expert
Joins Navtech Tutorial Instructional Team
3)
GALILEO Newsletter #21
4)
GPS Quiz #2
5)
White House
Outlines its Priorities for FY2004 Budget
6)
National Park Service Selects GPS-Photo Link
7) Questions for our Experts
8) GPS Textbook Available Exclusively from Navtech
9) Product News
10)
GPS/GNSS Calendar
11) Useful Links
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1)
Get Ready for ION GPS-2002! IT'S JUST 9 WEEKS AWAY!
It's time to make preparations to attend the world's largest
GPS/GNSS conference... ION GPS 2002 to be held in September in Portland, Oregon. Go to the ION website at
http://www.ion.org to get more information, register for the conference and make hotel reservations. Book your hotel by August 22 and
identify yourself as an ION Conference Attendee to secure the special rate.
The Navtech ION GPS-2002 Tutorial information can be found on our website. Go to http://www.navtechgps.com/seminars/GPStutorials/iongps2002.asp
for information on all 35 of our half-day tutorials to be
presented prior to the ION GPS-2002 conference.
When you get to the conference, make sure to stop by our exhibit at Booth 701/703.
Come see the products we sell, exciting equipment demonstrations, samples from our bookstore and course notebooks from our world class seminars.
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2) GALILEO Expert
Joins Navtech Tutorial Instructional Team
Marco Falcone, Ground Segment Engineering Manager for the European
Space Agency Galileo Project Office, will join instructors
Günter
Hein and Bernd Eissfeller to teach the technical portion of
Navtech's ION GPS-2002 Tutorials 740A & 740B "Galileo I & II: Design Options for the European GNSS-2".
See http://www.navtechgps.com/seminars/GPStutorials/740AB.asp
for detailed course outlines and http://www.navtechgps.com/seminars/instructors/instruct.asp
to find out more about our excellent instructors.
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3) GALILEO Newsletter #21
The European Commission's Genesis Office publishes periodic newsletters tracking GALILEO's progress. Issue 21 has just been released.
To access previous versions of the newsletter or to subscribe, visit the Genesis website at http://www.genesis-office.org.
"Galileo Information Day
To manage the development phase and to prepare the deployment phase, the Galileo Joint Undertaking is being set up, a form of original company envisaged by the provisions of Article 171 of
the EU Treaty. The formula selected ensures single and effective management of the programme. It is intended for encouraging a gradual participation of the private sector in the various phases
of the programme and allows for a combination of public and private financing.
In view of the multiple commercial repercussions connected with the growing markets of the navigation services by satellite in all
the fields of the European and world economic activity, the programme will be managed during the deployment and operational use phases by a concessionary company. To this end, a public call for tenders will be
organised in order to allow the designation of the private consortium which will be allotted the concession for deployment and use.
The European Commission will organise at the beginning of October
2002 an information day for enterprises wishing to participate in
the Galileo programme. Representatives from the Commission, the Galileo Joint Undertaking, ESA and experts will inform enterprises
on the development of the programme, the steps leading to the choice of the future
concessionaire and the numerous services based on satellite radio navigation. Simultaneous translation will allow for speeches in French, German and English.
Details on this event and the corresponding call for expression of
interest are available at:
http://www.europa.eu.int/comm/energy_transport/en/gal_how2_en.html."
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4) GPS Quiz #2
GPS Quiz - Part I Volume 2
(The author of the below questionnaire is Dr. Jayanta Kumar
Ray (email: jkray@accord-soft.com) of Accord Software &
Systems Private Limited, Bangalore, India. Accord Software and
Systems is a leader in programmable DSP-based GPS Receiver
Technology. The references for this questionnaire pinpointing
the page numbers where the answers can be found are given on the
website www.accord-soft.com
under the heading "GPS Quiz")
1. The first operational prototype of GPS satellite was launched in
a) 1960
b) 1973
c) 1978
d) 1981
2. The error contribution of the control segment in terms of the
ephemeris and clock parameter is about
a) 1-3 m
b) 10-12 m
c) 20-25 m
d) 30-40 m
3. A medium is dispersive if the refractive index of the medium is a function of the
frequency of the signal. The following medium is dispersive:
a) troposphere
b) ionosphere
c) both ionosphere and troposphere
d) neither ionosphere nor troposphere
4. The electron density in the ionosphere is
peak at about
a) 2 pm, local time
b) 2 pm, GPS time
c) 12 pm, local time
d) 12 pm, UTC time
5. The broadcast ephemeris from the GPS satellite has Keplerian parameters. The number
of Keplerian parameters broadcasted is
a) 6
b) 5
c) 4
d) 3
6. The absolute (i.e. no sign) minimum Doppler offset is for a satellite at
a) the horizon
b) the zenith
c) the horizon and the zenith
d) arbitrary elevation
7. The sources for specular and diffuse multipath errors are reflections from
a) smooth and rough surfaces respectively
b) rough and smooth surfaces respectively
c) smooth surfaces
d) rough surfaces
8. The GPS signal received power at the user antenna is maximum at
a) 0 deg elevation
b) 40 deg elevation
c) 60 deg elevation
d) 90 deg elevation
9. Z-count in the navigation data comes in every
a) 6 sec
b) 600 msec
c) 30 sec
d) 12.5 min
10. Generally the following loop is used for code tracking in a GPS receiver
a) FLL
b) PLL
c) DLL
d) Costas loop
Feeling confident? Then try these more advanced questions. Good luck!
1. Space-borne receivers generally have an average VDOP compared to
land based receivers:
a) higher
b) lower
c) the same
d) not related
2. While smoothing the code range by carrier phase, if the weight for the code
measurement is decreased rapidly (say in 3 steps in 3 sec), then
a) the smoothed pseudorange will be more noisy
b) the smoothed pseudorange will be more accurate
c) the smoothed pseudorange will be unbiased
d) the smoothed pseudorange will be biased
3. The NMEA message $GPGSV has fields for
a) latitude-longitude position
b) speed and heading
c) satellite elevation-azimuth-signal strength
d) all the above
4. The correlation values of GPS C/A (Gold) codes are
a) 1, -1/1023
b) 1, -1/1023, +63/1023
c) 1, -1/1023, +63/1023, -65/1023
d) 1, -1/1023, -63/1023, +65/1023
5. The following statement about the code and carrier multipath error is false:
a) code multipath has non-zero mean whereas carrier
multipath has zero mean especially in high multipath
environment
b) code multipath has an asymmetric error envelope
whereas carrier multipath has a symmetric error envelope
c) code multipath can be largely reduced by spacing the
early and late correlator in close time proximity, but there
is no such gain by doing so for carrier multipath
d) code multipath is less dependent of the pre-correlation
bandwidth whereas carrier multipath is highly
dependent on the pre-correlation bandwidth
Answers:
1. (c) 2. (a) 3. (b) 4. (a) 5. (a) 6. (b) 7. (a) 8. (b) 9.
(a) 10. (a)
Advanced 1. (b) 2. (d) 3. (c) 4. (c) 5. (d)
Grade your performance:
Excellent (13-15), Very good (11-12), Good (8-10)
References:
1. Kaplan, E.D. (1996), Understanding GPS Principles and
Applications, Artech House Publishers, Boston. Available
through
Navtech
GPS Supply.
2. Lachapelle, G. (1997), GPS Theory and Applications,
ENGO 625, Geomatics Engineering, The University of Calgary,
Calgary, Canada. Contact
Navtech GPS Supply for information.
3. ICD-GPS-200C (1993), Interface Control Document,
Navstar GPS Space Segment and Navigation User Interfaces,
Prepared by ARINC Research Corporation, California. See PDF at
NAVCEN’s
website. Paper copy available through Navtech
GPS Supply.
4. Misra, P. and Enge, P. (2001), Global Positioning
System: Signals, Measurements and Performance,
Ganga-Jamuna Press, Lincoln, Massachusetts. Distributed
exclusively by Navtech
GPS Supply.
5. NMEA (2000), National Marine Electronics
Association, NMEA 0183, Version 3.00
6. Parkinson, Brad W. and Spilker, James J. Jr. (1996), Global
Positioning System: Theory and Applications, Volume I,
American Institute of Aeronautics and Astronautics, Inc.,
Washington DC. Available through Navtech
GPS Supply.
7. Ray, J.K. (2000), Mitigation of GPS Code
and Carrier Phase Multipath Effects Using a Multi-Antenna
System, UCGE Reports Number 20136, Department of
Geomatics Engineering, the University of Calgary, Calgary,
Canada
8. RTCM SC-104 (1994), RTCM Recommended Standards for
Differential Navstar GPS Service, Version 2.1, Washington
DC. Available through the RTCM.
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5) White House
Outlines its Priorities for FY2004 Budget
07/16/2002 Dow Jones International News
(Copyright (c) 2002, Dow Jones & Company, Inc.)
WASHINGTON
The Bush administration released a short list of its priorities for the fiscal year 2004 budget, saying it is beginning work on
crafting the budget proposal which will be unveiled next February.
In its Homeland Security strategy report which it submitted to Congress, the administration said it wants to build up the FBI's
ability to analyze information, and it wants to create a new capacity to process intelligence on terrorist threats at the
Department of Homeland Security. The White House will seek funds
to increase the security of shipping containers which pose a smuggling risk and could hold weapons of mass destruction. In
addition, the White House will seek money to implement its "smart
borders" proposal, which will use technology to protect the
nation's borders. The administration will also seek a significant
boost in spending on the Coast Guard and will seek money to pay for
sensors that can detect nuclear and radiological weapons. The White
House said it wants to boost the ability of all government agencies
to communicate. Finally, the White House said it will support the
development of broad spectrum vaccines, anti-microbials and antidotes.
-By Alex Keto, Dow Jones Newswires; 202-862-9256; Alex.Keto@dowjones.com.
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6)
National Park Service Selects GPS-Photo Link
Fort Collins, Colorado, June 5, 2002
The National Park Service (NPS) recently ordered another 30
copiesof GPS-Photo Link. This purchase contributes to the
nation-wide roll out of GPS-Photo Link as
a new tool for the National Park Service
and parks around the country to link digital photos and GPS
information. To date, headquarters and individual NPS parks
have purchased over 75 copies. Now national parks
from Boston to Alaska will use GPS-Photo
Link by GeoSpatial Experts to map assets quickly
and simply.
Over the next few years the National Park Service intends to
inventory every single facility in over 350 park
units. GPS-Photo Link will help them
complete this job in a fraction of the time and
at a fraction of the cost. GPS-Photo Link will allow the NPS
to meet the requirement that they have a digital
photo and a geographic coordinate for
every asset, while providing good value, functionality
and flexibility.
(This item updated 7/22/02)
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7)
Questions for our Experts
Q: Do you know if the GPS PPS service has been re-evaluated in accuracy since the
removal of SA? My reason for asking is that the SPS service has been redefined with average accuracy of <= 13 meters (95%) which is less than what we have for the PPS service.
Dr. Chris Hegarty responds:
A: The U.S. Department of Defense is in the process of updating PPS performance
standards. Although the discontinuance of SA didn't affect PPS users (they could always remove SA effects),
PPS user equipment performance has gotten a lot better in recent years. PPS users today typically enjoy 95% horizontal positioning on the order of a few meters.
SPS users are now seeing 95% horizontal performance on the order of 6-7 meters. The main difference now between SPS and PPS users is that PPS users can calibrate for ionospheric delay errors because they have access to L2. Of course, some civil users also track L2 using semi-codeless techniques. Furthermore, once L2C and L5 are available, civil GPS accuracies will rival PPS accuracy.
One caution about the 13 m specification you mentioned for GPS SPS - it is defined for the GPS signal-in-space only (i.e., it excludes ionospheric and tropospheric errors, multipath, and receiver noise).
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8) GPS Textbook Available Exclusively from Navtech
Navtech is the exclusive distributor of the GPS textbook "Global
Positioning System: Signals, Measurement and Performance," by Dr.
Pratap Misra (MIT Lincoln Laboratory) and Dr. Per Enge (Stanford
University). This is not a compilation of papers, but a
comprehensive and cohesive text designed for use in graduate level
courses and for engineers who want to "self teach" GPS. To read a
review of the text, including comments from experts in the field,
follow this link: http://www.navtechgps.com/supply/2500.asp
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9) Product News
You spoke and we listened! Your requirement:
USB enabled Garmin
hand held and smart antennas without separate power. Our
solution: Navtech GPS Supply is integrating a high quality
RS-232
to USB converter with the Garmin GPS 35, 16 and 17 LVS
smart
antennas and the eTrex family of receivers. Most of these
receivers are WAAS enabled.
We draw power directly from the USB port and through put it to
the
GPS receiver eliminating the need for an external power source
for
the smart antennas and bypassing the internal batteries in
the
eTrex line of receivers. Navtech can provide the complete
solution
including the receivers or we can provide the cabling from
the
converter to the GPS receiver.
The receiver appears as a standard serial port on your
computer.
This avoids the problem that is common to some converters
that
show up as a USB or virtual port. The serial port is more
common
to software, especially older versions of software that
are
incompatible with a USB port or device. The included 8cm.
CD
includes installation software/drivers for the following
operating
systems (OS): Win ME, XP, 2000, 98 and iMac. Installation
manuals
are included as well as an uninstall program. Call today
for
available configurations and pricing or visit us online at
www.navtechgps.com.
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10)
GPS/GNSS Calendar
* 15-19 JULY 2002
United Nations/United States Workshop on
Global Navigation Satellite Systems (GNSS)
* 24-27 SEPT 2002 ION GPS 2002, Portland, OR
* 22-24 JAN 2003 ION National Technical Meeting, Disneyland
Paradise Pier Hotel, Anaheim, CA
* 23-25 JUNE 2003 ION Annual Meeting, Hyatt Regency Hotel,
Albuquerque, NM
* 9-12 SEPT 2003 ION GPS 2003, Portland, OR
* 22-25 APRIL 2003 GNSS 2003, Graz, Austria
More details about upcoming GPS/GNSS meetings can be found at
http://www.navtechgps.com/seminars/meetings.asp.
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11) Useful Links
To check the status of the GPS satellite constellation visit the
US Coast Guard Navcen website at http://www.navcen.uscg.gov/ftp/GPS/status.txt
A wide variety of useful links are available on the Navtech website. Visit
http://www.navtechgps.com/links.asp#space
to get to the information sources you need.
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SEND
US YOUR NEWS ITEMS, WITH SOURCES!
Carolyn McDonald, Editor
cmcdonald@navtechgps.com
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We hope the information will be useful to you!
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