SELF-TIMED DCPRS DESIGN REQUIREMENTS 



1. RF Power Output . The Effective Isotropic Radiated Power 

 (EIRP) of a DCPRS and antenna shall not exceed 50 dBm under 

 any combination of service conditions. 



2. Frequency Characteristics . The DCPRS transmitted RF shall 

 be in the 401.7-MHz to 401.85-MHz band. (See Table ].) 



3. Stability . 



A. Temperature . The transmitter carrier frequency 

 shall change by less than 0.5 parts per million 

 over the temperature range of -20°C to +50°C. 



B. Long-Term . The long-term stability (including 

 temperature variations) shall be better than one 

 part per million per year. 



C. Short-Term . The phase jitter on the transmit carrier 

 shall be less than 3° RMS. 



4. Electromagnetic Interference (EMI) . All transmitter spurious 

 emissions, when measured with modulation and with antenna and 

 diplexer connected, shall be down from the unmodulated carrier 

 level by 50 dB. 



5. Transmission Format . After a minimum of 4.9 seconds of unmod- 

 ulated carrier, the carrier shall be modulated with the bit and 

 message synchronization patterns which are at least 2.4 seconds 

 of alternate 1, data bits, and the 46-bit preamble consisting 

 of the 15-bit MLS sync word followed by the 31-bit BCH command 

 word. Maximum duration of this preamble shall be 9.0 seconds. 

 The binary data shall be Manchester-encoded 8-bit ASCII, 



odd parity, and shall modulate the carrier in the following 

 manner: a data "0" shall consist of +60° (+5°) carrier phase 

 shift for 5 milliseconds followed by -60° (+5°) carrier phase 

 shift for 5 milliseconds, and a data "1" shall consist of -60° . 

 carrier phase shift for 5 milliseconds followed by +60° carrier 

 phase shift for 5 milliseconds. Data rate shall be 100 BPS 

 +0.1 BPS. (See Figure 1.) 



6. End of Transmission . Immediately after sending the sensor data, 

 the DCPRS shall transmit three 8-bit ASCII, odd parity. 



End of Transmission (EOT) characters contiguously with the ASCII 

 sensor data characters (no break) and return to the standby 

 condition . 



7. Fall Safe Design . The DCPRS shall incorporate a "fail-safe" 

 design feature such that malfunctioning of the equipment shall 

 in no way cause continuous transmission. 



8. Antenna Polarization . Polarization shall be right-hand circu- 

 lar, according to IEEE Standard 65.34.159. 



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