Engineering tests of SMS-2 (op. cit.) showed that the average 

 time delay of platform site interrogation (from transmission of 

 address identifier to reception of response preamble) was 12.6 

 seconds. 



2.5 Data Recovery-Central Distribution Facility (CDF) 



2.5.1 Recovered Data Characteristics 



Recovered data and other messages sent from the CDF to the users 

 are in data record form, consisting of a heading and sensor 

 platform data. Each record represents one of the following: 



(1) Platform sensor response. 



(2) Abnormal platform response message. 



(3) Operator message. 



(An "abnormal platform response message" is a "canned" message from 

 the DPS describing an unexpected event in a platform response, and 

 is preceded by two carets (AA) for rapid identification.) 



Each normal platform response data record contains: 



(1) The platform sensor address identifier (in hexadecimal 

 representation ) . 



(2) A question mark (?) if the address had bit errors or 

 a space if the address was received without error. 



(3) The time platform data were received, as day-of-year 

 (3 characters), hour (2 characters), minute (2 

 characters) and second (2 characters) of Coordinated 

 Universal Time. 



(4) Received data (as ASCII characters). 



Characters received with parity errors will be replaced in the 

 data with either a dollar sign ($) or NUL character, depending on 

 the means of dissemination as explained in 2.5.3 below. The EOT 

 characters required to terminate the platform transmission are 

 not included with data in the record. (For further details 

 regarding this general subject, refer to the user interface 

 manual listed in the references.) 



2.5.2 Error Checks and Abnormal Responses 



The CDF identifies as abnormal all responses with error conditions. 

 All scheduled response messages will be routed to users even if 

 the address is received in error. (Only unscheduled unrecognizable 

 messages will not be disseminated. ) 



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