# Presentation: 209528

## GOES Data Collection System --Alternate Methods of Data Reception

- Ernest Dreyer
- United States Geological Survey

## Overview

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

## Current Methods of Data Reception

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

## 	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

## 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

## Direct Readout Ground Stations

## Direct Readout Ground Stations 				(DRGS)

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

## 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.

## NOAAPORT

## 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.

## 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.

## DOMSAT/Local Readout Ground Stations inUSGS GOES Data Collection System

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

**Notes:**
Provides support for over 4000  USGS sites.
Supports two types of transmissions:
self-timed transmissions which normally occur every 4 hours, and
random transmissions which occur when a threshold is exceeded.

## 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.

## 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.

## USGS Local Readout Ground Sites

**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

**Notes:**
15 LRGSs connected to the GEONET /DOInet 
Each WRD district has a primary and several secondary LRGSs.
Each WRD district connects with a LRGS as a TCP/IP client to receive real-time data.
Each district automatically connects with a secondary LRGS if its primary LRGS fails.

## Slide 16

## 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

**Notes:**
LRGS software will support a network Application Programming Interface using CORBA.
Application software will be written in Java as thin clients using the network API.
Common object request broker application?

## 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)

## 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.

## 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.

## USGS/COE Effort for Standardizing Site Configurations

**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.

**Notes:**
Standards for expressing site configurations
The USGS in cooperation with the STIWG is a lead participant in an effort to standardize  the decoding software for GOES transmitters across agencies.  
This will facilitate the sharing of data by all agencies.

The approach will be to
express metadata and decoding information using the (eXtensible  Mark-up Language (XML) , and 
create a Java decoding object that uses the metadata and configuration information expressed in XML.
The XML definitions would be published as a recognized standard  ( perhaps GOESML ) by the GOES community. DTD=data type definitions

## USGS/COE Decoding Software