GOES Data Collection System Alternate Methods of Data Reception

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GOES Data Collection System --Alternate Methods
of Data Reception

• Ernest Dreyer
• United States Geological Survey

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Overview

• Current Methods of Data Reception
• Future Methods under consideration
• Some Problems and Solutions

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Current Methods of Data Reception

• Direct connection to DAPS
• Direct Readout Ground Stations
• NOAAPORT
• DOMSAT and Local Readout Ground Stations

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Direct Connection to DAPS

• DAPS supports
• A limited number of dial up connections
• Telnet and ftp connections using the internet
• Remarks
• User interface is a command-line, interactive
  interface.
• Useful for viewing or downloading small amounts
  of data.
• Unsuitable for real-time processing of large data
  networks

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Direct Readout Ground Station (DRGS)

• Ground stations that receive data directly from
  the GOES satellite.
• Current DRGSs receive data from GOES channels
  using hardware demodulators
• A demodulator can receive a transmission from a
  single channel at any given time.
• Thus, two DCPs transmitting at the same time on
  different channels require two demodulators on
  the DRGS

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Direct Readout Ground Stations
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Direct Readout Ground Stations (DRGS)

• Advantages
• Most direct method of data reception.
• Allows almost complete control of data collection
  from field to users data processing system.
• Considerations
• Initial cost and ongoing maintenance and support
  of equipment.
• Management of DCP assignments and channel
  demodulators.
• Data distribution and backup.

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NOAAPORT

• Data distribution satellite operated by NOAA.
• Used by the NWS to distribute most NWS data
  products.
• Distributes all GOES DCS data on one of its four
  channels.

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NOAAPORT
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NOAAPORT

• Advantages
• Well supported by many vendors making NOAAPORT
  receive sites
• Contains NWS products in addition to GOES DCS
  data.
• Considerations
• Cost and maintenance of equipment.
• Multiple failure points.

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DOMSAT and Local Readout Ground Stations (LRGS )

• DOMSAT is a commercial satellite that is used to
  distribute GOES data.
• The entire GOES data stream is received at
  Wallops Island by NESDIS and immediately
  retransmitted to DOMSAT
• Receive sites called Local Readout Ground
  Stations(LRGS) have been developed to receive the
  data from DOMSAT.

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DOMSAT/Local Readout Ground Stations inUSGS
GOES Data Collection System
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Local Readout Ground Stations

• Continuously receives all GOES data transmitted
  from Wallops Island.
• Supports various software packages that provide
• Network filtering to eliminate unwanted
  transmissions.
• Distribution of data over a network using
  client/server protocols.

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Local Readout Ground Stations

• Advantages
• Relatively inexpensive.
• No GOES demodulators to manage.
• Good network connection permitting good
  capabilities for backup.
• Considerations
• Relies on DAPS to transmit data to DOMSAT.
• Uses Ku-band which can degrade under certain
  environmental conditions.
• Footprint of DOMSAT is North America.

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USGS Local Readout Ground Sites

• 19 LRGSs connected to the DOINET
• Each District has a primary and several secondary
  LRGSs
• Should a primary LRGS fail, a district is
  automatically connected to a secondary LRGS

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USGS and LRGS Software

• USGS has supported Software Improvements for
  LRGSs
• Developed software that runs on Linux
• The software supports
• Server/client protocol for the distribution of
  real-time data
• Network backup between LRGSs
• Network API using CORBA
• Software is written in C and Java
• Software is open source

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Future Methods of Data Reception

• DRGS with hardware demodulators replaced with
  software demodulators using digital signal
  processing (DSP).
• LRIT/EMWIN
• Likely replacement for DOMSAT
• Network Connection to DAPS ( DAPS II)

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Some Problems and Observations

• No standard user reception interface for each of
  the methods of distribution.
• Each data reception method has a different
  interface.
• This makes difficult the sharing of data
  reception devices for backups.
• DAPS II will use client/server protocols similar
  or identical to those developed for the LRGSs
  which will make the LRGS client software usable
  with both distribution systems.

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Some Problems and Observations

• No standard method of decoding data.
• The small bandwidth of GOES does not allow the
  transmission of meta-data that can completely
  describe the transmitted data.
• This requires decoding software.
• Various decoding methods have been devised and
  are in use by different GOES reception devices.
• This makes it difficult for users who share data.

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USGS/COE Effort for Standardizing Site
Configurations

• Goal is to standardize decoding software for GOES
  transmitters
• Approach
• Use XML for metadata and decoding information
• Write decoding application in Java
• Publish the XML DTD as a standard for GOES
• Software developed is open source.

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USGS/COE Decoding Software