Comtech EF Data CDM-500, Installation And Operation Manual

Page: 62 / 88

Rev. 1.3 A–1
A
Appendix A.
SUMMARY OF SPECIFICATIONS
A.1 Modulator
Data rate range Overall, 2.4 - 512 kbps
2.4 kbps - 256 kbps, Rate 1/2 BPSK
4.8 kbps - 512 kbps Rate 1/2 QPSK
7.2 kbps - 512 kbps Rate 3/4 QPSK
8 kbps - 512 kbps Rate 7/8 QPSK
Operating modes Transparent, Closed Network
Proprietary EDMAC framed mode - 5% overhead
addition
Scrambling Transparent mode - per CCITT V.35
EDMAC mode - externally synchronized
FEC Convolutional, k=7, standard polynomials
BPSK: Rate 1/2
QPSK: Rate 1/2, Rate 3/4 and Rate 7/8
Transmit filtering 6th order Butterworth, aperture and group delay
equalised per INTELSAT IESS 308 (32 to 256 tap FIR
digital filter implementation)
Output frequency 52 - 88 MHz, 100 Hz resolution
(140 MHz band optional, 104 - 176 MHz)
Stability ±1ppm, 0 to 40
°
C
Harmonics and
spurious Better than -55 dBC/4 kHz (typically <-60 dBC/4kHz)
Transmit on/off
ratio 55 dB minimum
Output phase
noise < 0.24 rms double sided, 100 Hz to 250 kHz
(minimum of 22 dB better overall than the INTELSAT
IESS 308/308 requirement)
Output power 0 to -20 dBm, 0.1 dB steps
Accuracy ±0.5 dB over frequency and temperature