09-05-2011, 03:38 PM
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SATRACK
WHAT IS SATRACK
SATRACK is an evaluation methodology developed for the guidance system of the ballistic missiles.
It is responsible for accuracy evaluation of the Navy’s Strategic Weapon System.
It has the ability to receive ,record and track the satellite signals.
It obtains whole data from the test flights and gives a guidance error model.
Gives the best flight path for the missile.
Detects small error contributors in calculating distances.
GPS signals
The signals for the GPS satellite navigation are two L-band frequency signals.
called L1 and L2.
L1 operates at 1575.42 MHz.
L2 operates at 1227.60 MHz.
Modulations Techniques
Modulation techniques used are:
1. Narrow band clear/acquisition code.
2. Wide band encrypted P code.
L1 is modulated using the narrow band C/A code only.
It gives an accuracy of close to a 100m only.
L2 is modulated using the P code.
It gives an accuracy close to 10m only.
The parameters that a GPS signal carries are latitude, longitude, altitude and time.
The modulations applied to each frequency gives the measurements used to determine the distances to each satellite.
NEED OF SATRACK
The evaluation concept of very early weapons systems depended on the impact scoring technique.
The missile was shot and the accuracy was formulated on the scoring or the target destruction.
This evaluation method was unacceptable for evaluating the more precise requirements of the latest systems.
Contd…
The radar systems did not provided the needed accuracy or range in the broad ocean test ranges.
A new methodology was needed that provided a much improved flight-test environment.
SATRACK was developed with the necessary hardware and telemetry stations.
SATRACK MEASUREMENT CONCEPT
Contd…
The main parts are:
GPS satellites.
missile translator.
and ground telemetry stations.
Missile receives the signals from the GPS satellites.
translated to another frequency and sent to the ground telemetry stations.
The station records the data for playback and for post processing.
signals received at the missile are translated to S-band frequencies using translators.
GPS Translator
This hardware is fixed in the missile.
It receives the GPS signals and amplifies it, shifts to frequency known as
S-band signals.
They are amplified again for transmission to one or more ground stations.
GPS TRANSLATORS
Types Of GPS Translators
Two types of GPS Translators :
Analog translators.
Digital translators.
Analog translators heterodyne the L-band signal
to S-band.
Digital translators convert the received L-band signal to a digital signal and in turn to S-band and transmit it to ground stations.
PORTABLE GROUND EQUIPMENT
It is used for the post flight processing and tracking of signals.
The raw data processed are given to Kalman filter which gives navigation solution for missile.
The hardware has undergone lot of redesign due to evolvement of new translators , receivers.
Processes L1/L2 signals.
SATRACK CONFIGURATION
For a number of days GPS signals are received, tracked, and recorded at the GPS tracking sites.
During the flight, GPS signals are received , translated and transmitted to the surface station(s).
A tracking antenna at the station receives the missile signals, separates the various components and records the data.
The post-flight process uses the recorded data to give satellite ephemerides from the post-flight receiver.
After the datas are corrected it is used by the missile processor to produce the flight test data products.
The data with the processed telemetry data provide the tracking aids for the post flight receiver and measurement estimates for the missile processor.
APPLICATIONS
Evaluation capability for cumulative flight test accuracy.
It is used in Army and Air Force missile test applications.
It provides a unique monitoring function that is critical to the maintenance of the Navy’s strategic weapon system.
ADVANTAGES
It provides the best flight path for the missile.
The full digital implementation of processing facility leads to big improvement over analog circuitry.
It acquires the signal with no delay.
It can support potential new and extremely demanding tactical strike scenarios.
DISADVANTAGES
Large amount of infrastructure is needed to support it.
Implementation of large Kalman filter to process technique
CONCLUSION
SATRACK is a significant contributor to the operational success of the weapons system.
It provides a monitoring function that is critical to the maintenance of the weapon system.
The development and research has brought the latest in GPS receiver, translators, data recorders.
Many sophisticated tools for optimal striking target were developed.
Special tests have shown that high accuracy can be achieved to support new weapons system.
SATRACK
WHAT IS SATRACK
SATRACK is an evaluation methodology developed for the guidance system of the ballistic missiles.
It is responsible for accuracy evaluation of the Navy’s Strategic Weapon System.
It has the ability to receive ,record and track the satellite signals.
It obtains whole data from the test flights and gives a guidance error model.
Gives the best flight path for the missile.
Detects small error contributors in calculating distances.
GPS signals
The signals for the GPS satellite navigation are two L-band frequency signals.
called L1 and L2.
L1 operates at 1575.42 MHz.
L2 operates at 1227.60 MHz.
Modulations Techniques
Modulation techniques used are:
1. Narrow band clear/acquisition code.
2. Wide band encrypted P code.
L1 is modulated using the narrow band C/A code only.
It gives an accuracy of close to a 100m only.
L2 is modulated using the P code.
It gives an accuracy close to 10m only.
The parameters that a GPS signal carries are latitude, longitude, altitude and time.
The modulations applied to each frequency gives the measurements used to determine the distances to each satellite.
NEED OF SATRACK
The evaluation concept of very early weapons systems depended on the impact scoring technique.
The missile was shot and the accuracy was formulated on the scoring or the target destruction.
This evaluation method was unacceptable for evaluating the more precise requirements of the latest systems.
Contd…
The radar systems did not provided the needed accuracy or range in the broad ocean test ranges.
A new methodology was needed that provided a much improved flight-test environment.
SATRACK was developed with the necessary hardware and telemetry stations.
SATRACK MEASUREMENT CONCEPT
Contd…
The main parts are:
GPS satellites.
missile translator.
and ground telemetry stations.
Missile receives the signals from the GPS satellites.
translated to another frequency and sent to the ground telemetry stations.
The station records the data for playback and for post processing.
signals received at the missile are translated to S-band frequencies using translators.
GPS Translator
This hardware is fixed in the missile.
It receives the GPS signals and amplifies it, shifts to frequency known as
S-band signals.
They are amplified again for transmission to one or more ground stations.
GPS TRANSLATORS
Types Of GPS Translators
Two types of GPS Translators :
Analog translators.
Digital translators.
Analog translators heterodyne the L-band signal
to S-band.
Digital translators convert the received L-band signal to a digital signal and in turn to S-band and transmit it to ground stations.
PORTABLE GROUND EQUIPMENT
It is used for the post flight processing and tracking of signals.
The raw data processed are given to Kalman filter which gives navigation solution for missile.
The hardware has undergone lot of redesign due to evolvement of new translators , receivers.
Processes L1/L2 signals.
SATRACK CONFIGURATION
For a number of days GPS signals are received, tracked, and recorded at the GPS tracking sites.
During the flight, GPS signals are received , translated and transmitted to the surface station(s).
A tracking antenna at the station receives the missile signals, separates the various components and records the data.
The post-flight process uses the recorded data to give satellite ephemerides from the post-flight receiver.
After the datas are corrected it is used by the missile processor to produce the flight test data products.
The data with the processed telemetry data provide the tracking aids for the post flight receiver and measurement estimates for the missile processor.
APPLICATIONS
Evaluation capability for cumulative flight test accuracy.
It is used in Army and Air Force missile test applications.
It provides a unique monitoring function that is critical to the maintenance of the Navy’s strategic weapon system.
ADVANTAGES
It provides the best flight path for the missile.
The full digital implementation of processing facility leads to big improvement over analog circuitry.
It acquires the signal with no delay.
It can support potential new and extremely demanding tactical strike scenarios.
DISADVANTAGES
Large amount of infrastructure is needed to support it.
Implementation of large Kalman filter to process technique
CONCLUSION
SATRACK is a significant contributor to the operational success of the weapons system.
It provides a monitoring function that is critical to the maintenance of the weapon system.
The development and research has brought the latest in GPS receiver, translators, data recorders.
Many sophisticated tools for optimal striking target were developed.
Special tests have shown that high accuracy can be achieved to support new weapons system.
