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Cellular forums Home > Archive > GPS > September 2007 > GPS Receivers using new WAAS signals may need software/firmware upgrades
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GPS Receivers using new WAAS signals may need software/firmware upgrades
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| Sam Wormley 2007-09-12, 10:33 pm |
| FAA CHANGES WAAS GPS CORRECTION SERVICE
NDSU Extension Service
10 September 2007
Grand Forks Herald
FARGO, N.D. -- The Federal Aviation Administration has made changes
to the Wide Area Augmentation Service that affects the global
positioning system correction service used by farmers and many other
users. These changes require that most GPS units used for
agricultural applications, such as tractor guidance systems and
combine yield monitors, need software updates to continue to
function.
WAAS is a system of satellites and ground stations that provide GPS
signal corrections to increase accuracy so that it can be used in
precision flight approaches for commercial aircraft. The ground
stations throughout North America monitor and measure the GPS signal.
The measurements from these reference stations are routed to two
master stations that generate and send the corrected messages to
geostationary satellites.
These satellites broadcast the corrected messages back to earth,
where WAAS-enabled GPS receivers apply the corrections to their
computed GPS position. Many farmers use the free WAAS correction
service with their farm GPS applications.
In late July, the FAA completed the transition from two older
geostationary satellites to two new ones. The new satellites are PRN
135 and PRN 138. Most GPS units on tractors and other farm equipment
are configured to receive GPS correction signals from the older
satellites, but not the new ones.
The procedure to configure GPS units to receive the new satellite
signals is different for the various brands and models. Some
manufacturers require the units be returned to the dealer or factory
for updating. Some allow users to download the updates from the
Internet and provide instructions for the owner to do his or her own
updates. Some units have been preprogrammed to search for the
strongest correction signals available, so those units will not need
updates.
Users quickly can discover whether their unit is using the signals
from the new satellites by turning it on and trying it in
WAAS-enabled mode. All GPS units display some kind of a digital
indication, such as the letters DGPS, when they are using a
differential correction service.
The FFA decommissioned both of the older satellites in July, so if a
unit displays a differentially corrected GPS position after July 31,
when set to use the WAAS service, it does not require an update. If
the GPS unit does not display a differentially corrected position, it
needs updating.
Other differential correction services include OmniSTAR, John Deere
SF1 or SF2 or the Nationwide Differential GPS (formally named the
Coast Guard Beacon System). These differential correction services
are not affected by the changes to WAAS.
Most WAAS-enabled handheld GPS units are preprogrammed to search for
available WAAS satellites and do not require software updates.
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| Bob Gardner 2007-09-16, 3:33 pm |
| How ironic. Grand Forks is the home of the U of North Dakota, which has an
excellent aviation program that graduates dozens of general aviation pilots
every year. A very small percentage of those pilots will become airline
pilots, but all of those who stay in flying as a career will be using WAAS.
Bob Gardner
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:q80Gi.99373$Fc.86568@attbi_s21...
> FAA CHANGES WAAS GPS CORRECTION SERVICE
> NDSU Extension Service
> 10 September 2007
> Grand Forks Herald
>
> FARGO, N.D. -- The Federal Aviation Administration has made changes
> to the Wide Area Augmentation Service that affects the global
> positioning system correction service used by farmers and many other
> users. These changes require that most GPS units used for
> agricultural applications, such as tractor guidance systems and
> combine yield monitors, need software updates to continue to
> function.
>
> WAAS is a system of satellites and ground stations that provide GPS
> signal corrections to increase accuracy so that it can be used in
> precision flight approaches for commercial aircraft. The ground
> stations throughout North America monitor and measure the GPS signal.
> The measurements from these reference stations are routed to two
> master stations that generate and send the corrected messages to
> geostationary satellites.
>
> These satellites broadcast the corrected messages back to earth,
> where WAAS-enabled GPS receivers apply the corrections to their
> computed GPS position. Many farmers use the free WAAS correction
> service with their farm GPS applications.
>
> In late July, the FAA completed the transition from two older
> geostationary satellites to two new ones. The new satellites are PRN
> 135 and PRN 138. Most GPS units on tractors and other farm equipment
> are configured to receive GPS correction signals from the older
> satellites, but not the new ones.
>
> The procedure to configure GPS units to receive the new satellite
> signals is different for the various brands and models. Some
> manufacturers require the units be returned to the dealer or factory
> for updating. Some allow users to download the updates from the
> Internet and provide instructions for the owner to do his or her own
> updates. Some units have been preprogrammed to search for the
> strongest correction signals available, so those units will not need
> updates.
>
> Users quickly can discover whether their unit is using the signals
> from the new satellites by turning it on and trying it in
> WAAS-enabled mode. All GPS units display some kind of a digital
> indication, such as the letters DGPS, when they are using a
> differential correction service.
>
> The FFA decommissioned both of the older satellites in July, so if a
> unit displays a differentially corrected GPS position after July 31,
> when set to use the WAAS service, it does not require an update. If
> the GPS unit does not display a differentially corrected position, it
> needs updating.
>
> Other differential correction services include OmniSTAR, John Deere
> SF1 or SF2 or the Nationwide Differential GPS (formally named the
> Coast Guard Beacon System). These differential correction services
> are not affected by the changes to WAAS.
>
> Most WAAS-enabled handheld GPS units are preprogrammed to search for
> available WAAS satellites and do not require software updates.
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