6. End of Transmission 



Immediately after sending the sensor data, the DCPRS shall 

 transmit 31-bit End-of-Transmission (EOT) code (bit pattern 

 0010000010111010100111100011) continuously with the sensor 

 data (no break) and return to the standby mode. 



The first 8 bits of the 31-bit EOT shall be the International 

 Alphabet No. 5, 8 bits EOT (ODD parity Po): 



First transmitted bit - 0010000010111011010100111100011 last 



tranaidtted 

 I I bit 



lA. No. 5 EOT 



31 bits PRN sequence 



7. Fail-Safe Design 



The DCPRS shall incorporate a fail-safe design feature such 

 that malfunctioning of the equipment shall in no way cause 

 discontinuous transmission. Furthermore, provision shall be made 

 to automatically terminate the transmission at a time not to 

 exceed the platform's allocated transmission plus 30 seconds. 



8. Antenna Polarization 



Polarization shall be right-hand circular according to CCIR 

 Report No. 321 (Xlllth Plenary Assembly, 1974 - Vol. XII). 



9. Timing Accuracy 



The timer that determines the DCPRS reporting time shall be 

 of sufficient accuracy to ensure that the DCPRS reporting 

 time is maintained to within 30 seconds of its assigned 

 reporting time. The timer shall provide for a reporting 

 interval of 1 to 12 hours in 1-hour steps. Furthermore, 

 the timer shall be capable of being set in steps of 60 seconds. 



10. Clock Output 



The DCPRS shall provide a 100 Hz clock frequency. This frequency 

 shall be used to clock in the reply data. The 100-Hz clock 

 frequency shall have a long-term temperature stability 

 better than 50 parts per million. 



11 . Data Input 



The DCPRS shall accept, from an interface unit with environmental 

 sensors or manual data input device, a serial bit flow NRZ-L, 

 100 bits/s coded in International Alphabet No. 5. (See Fig. 3.) 



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