(2) A sensor data interface to provide ASCII data coding and 

 formatting. 



(3) A timer, or sensor threshold logic, to initiate transmission 

 on a regular timed basis, or on the detection of conditions 

 exceeding predetermined levels. 



The addition of an UHF receiver capable of receiving and decoding the 

 command/interrogate signal provides the capability of remotely commanding 

 sensor platform responses. 



To qualify for participation in the GOES DCS, the data being collected 

 must be observations and measurements of physical, chemical, or 

 biological characteristics of the Earth or its surrounding space. 

 A wide variety of sensor platforms can work with the Data Collection 

 System, for example: 



(1) fixed location sensors; temperature, wind, and rainfall 

 gages on land and sea; river level and tide gages; 

 seismic detectors; experimental environmental monitors. 



(2) mobile sensors; balloon and aircraft-borne monitors; 

 free-floating ocean environmental sensors; shipboard 

 weather and oceanographic reporting stations. 



Any platform that has been demonstrated to meet the DCS performance 

 specifications (Appendix C) may be used. A current list of approved 

 platforms may be obtained from NESS. 



1.2.6 How Are Transmitter Frequency Assignments Obtained? 



When an organization is accepted as a DCS user, the sensor platform 

 transmitter channel frequency assignments are provided by NESS. The 

 user, however, is responsible for obtaining authority from the 

 appropriate national agencies to operate each platform transmitter 

 at its deployed location. 



1.2.7 How Do the Sensor Data Reach the User? 



Transmission of data from the user sensor platform may be initiated 

 in several ways. The platform site transmitter may be commanded to 

 transmit the sensor data, using the interrogation capability of the 

 DCS. The transmitter may be activated at regular time intervals 

 under the control of an internal timer. Sensor threshold or abnormal 

 conditions may be used to trigger transmission of emergency informa- 

 tion or data requiring immediate attention (such as seismic activity). 

 Generally, transmissions initiated by different means (interrogated, 

 self-timed, or emergency) will not share occupancy of a common response 

 channel . 



Each sensor platform site transmitter is assigned at least one 31-bit 

 address identifier. The address identifiers are part of the required 

 format for transmission of sensor data, and are used by the data 

 processing subsystem to route the data to the user. Once a message 

 is received by the DCS, it is entered in the system events log and 



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