CDM-600 Satellite Modem Revision 7
Physical Description MN/CDM600.IOM
4–3
4.3.2 Rx and Tx IF Connectors (J1 and J2)
The IF port connectors are both a 50Ω BNC female type. 75Ω cable connectors (male)
will have no problem mating with this 50Ω type. The electrical impedance presented by
these connectors is controlled internally by an RF-switching arrangement. This selection
between 50Ω and 75Ω is controlled either via the front panel menus, or via the remote
control bus.
4.3.3 Overhead Data Connector (P3A)
The Overhead data connector is a 25-pin ‘D’ type male (DB25-M). It is used for passing
components of INTELSAT specified overhead frame structures. These include 64 kbps
EIA-422 and 1/16 IBS overhead ESC at EIA-232. The IDR backward alarm inputs are
found on this connector.
4.3.4 Data Interface Connector (P3B)
The Data connector is a 25-pin ‘D’ type female (DB25-F). This connector conforms to
the EIA-530 pinout, which allows for connection of different electrical standards,
including EIA-422, V.35, and EIA232. A shielded 25-pin ‘D’ type provides a very solid
solution to EMC problems, unlike the sometimes used V.35 Winchester connector.
IMPORTANT
It is the responsibility of the user to provide the appropriate cables to
connect to this EIA-530 connector.
4.3.5 External Reference Connector (J9)
This is a BNC female connector. It is used for operating the buffer with an external
station reference. It requires an EIA-422 compatible level, so this unbalanced input
should have a zero volt offset and a swing of at least ± 2V into the 120 Ω termination
provided.
4.3.6 Audio Connector (P4A)
The Audio connector is a 9-pin ‘D’ type female (DB9-F). It is used for the two 32 kbps
ADPCM audio inputs and outputs (600 Ω transformer coupled, balanced signals). These
can be used for both ESC voice circuits in IDR mode, or as the primary data (FAST
option).