CDM-625 Advanced Satellite Modem
Revision 1
Introduction
MN-0000036 (Ref MN/CDM625.IOM)
Clocking options
Internal, ±0.06 ppm (SCT)
External, locking over a ±100 ppm range (TT)
Loop timing (Rx satellite clock) - supports asymmetric operation - Rx and Tx data rates need not be identical
External Clock
G.703 Clock Extension mode – internal ST clock can be slaved to an external T1 or E1 G.703 signal, and a
G.703 timing signal re-constituted at the distant end of the link, regardless of the actual link data rate
External TX
Carrier Off
By TTL 'low' signal or external contact closure - hardware function automatically over-rides processor
BUC Reference
(10 MHz):
Phase Noise
On center conductor of L-Band output connector; 10.0 MHz
±
0.06 ppm (internal reference selected)
0.0 dBm,
±
3 dB; programmable ON/OFF
Source: either Internal Modem Reference or External Reference (10 MHz)
dB/Hz Frequency
Offset
-105
10
Hz
-125
100
Hz
-138
1
kHz
-148
10
kHz
-150
100
kHz
BUC Supply Voltage
Standard unit has no BUC supply.
Optional BUC Supply
•
24VDC, 4.17 Amps maximum, 100W
•
48VDC, 3.125 Amps maximum, 150W @ 50
o
C (180 watts @ 30
o
C)
•
Supplied through Tx IF center conductor and selectable ON/OFF via M&C control.
BUC Current Monitor
Min/Max programmable current alarm thresholds.
Tx Carrier ON Delay
Selectable feature power on to allow internal ovenized reference to stabilize before turning on Tx carrier.
Intelligent algorithm minimizes delay time based on internal temperature at power-up.
BUC Monitoring
Power level, temperature, power class, PLL lock.
Uses ND Satcom/Global VSAT Forum specification for FSK control and monitoring.
1–11
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
CDM-625
Modulator
typically < -50 dB, and
guaranteed to be
< -45 dB at offsets
> 0.75 Rs
Comtech EF Data
CDM-625 Transmit
Power Spectral
Density, referred to
symbol rate
Symbol Rate, Rs
Spectral
density, dB
Intelsat
IESS
308/309
Limit
Intelsat
IESS
308/309
Limit
