SECTION 2 

 A CLOSER LOOK AT THE DCS 



2.1 DCS General Operation 



The GOES Data Collection System (DCS) is a communication system 

 designed to be used by many organizations having the need to relay 

 environmental data from remote sensors to the user's processing 

 center on a timely basis. The system is designed to accommodate 

 10,000 individual sensor platform transmissions per hour operating 

 in three possible modes: 



(1) Interrogated; the sensor platform transmits 

 its data in response to an interrogation 

 signal from the CDF. 



(2) Self timed; the sensor platform transmits its data 

 at fixed (synoptic) intervals controlled by a timer 

 located within the sensor platform. 



(3) Emergency; the sensor platform transmits its data 

 after a predetermined sensor threshold (trigger) 

 level has been exceeded. 



Figure 3 presents a pictorial diagram of the Data Collection System 

 showing its major functional subsystems: 



(1) Deployed sensor platforms; discussed in Section 2.2. 



(2) East and West spacecraft; discussed in Section 2.3. 



(3) Command and Data Acquisition Station (CDA); discussed 

 in Section 2.4. 



(4) CDF and user dissemination circuits; discussed in 

 Section 2.5. 



The radio frequency plan for the DCS is shown in Figure 3. The exact 

 frequency or frequency range is associated with each specific 

 function . 



2.2 Sensor/Platform Interface 



2.2.1 Sensor Data Format 



The CDF computer is programed to make only those modifications to the 

 sensor data necessary to disseminate the data to the user. No 

 capability is provided for analysis or interpretation of sensor data 

 or for code conversion or error correction. Sensor data are expected 

 to be binary-coded ASCII characters (conforming to the 128-character 

 code set shown in Figure 4) transmitted serially (least-significant 

 bit first), with odd parity determining the eighth bit for each 



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