Premier Mounts Modem CDM-600 사용자 설명서

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CDM-600 Satellite Modem 
Revision 7 
Offset QPSK Operation 
MN/CDM600.IOM 
8–2  
The two consequences of this are: 
 
1.  Acquisition may be longer, especially at low data rates. 
 
2.  The acquisition threshold is higher than for normal QPSK, although the 
demodulator will maintain lock down to its normal levels. For Firmware 
Versions prior to 1.3.1, the acquisition thresholds are as follows: 
 
7.0 dB Eb/No for Rate 1/2 
5.2 dB Eb/No for Rate 3/4 
4.8 dB Eb/No for Rate 7/8 
4.0 dB Eb/No for Uncoded operation (No FEC) 
 
Firmware Versions of 1.3.1, or higher, have improved these figures by 
approximately 2-3 dB.