Connecting CG and TX Boards to 75 Ohm E1 Trunks

When connecting NMS boards to 75-ohm E1 trunks, attention must be paid to the configuration of the board based on the physical connection method used.

NMS provides two ways to connect to 75-ohm E1 trunks – Signal Entry Panels (SEPs) and splitter cables. The SEPs include a balun to convert impedances to 75 ohms, but the splitter cables do not. This will affect the configuration of the NMS board as described below.

Board Categories

For the purposes of this discussion, NMS boards fall into two categories – those that cannot be configured for E1/75 ohm operation and those that can.

1. All TX boards and those CG boards with RJ-21 or Mini RJ-21 connectors can only be configured for T1 or E1/120. These boards require a balun to connect to a 75-ohm E1 trunk (either provided by the customer or included in the SEP).

    Specifically, the boards in this category include:

·          All TX boards

·          8-trunk CG 6060C cPCI boards (RJ-21 only, not RJ-48C)

·          16-trunk CG 6060C cPCI boards (RJ-21)

·          8-trunk CG 6565 PCI boards (MRJ-21)

·          All CG 6565C cPCI boards (RJ-21)

When using NMS components to connect these boards to 75-ohm E1 trunks, the first step is to use a SEP that will convert the RJ-21 or MRJ-21 connectors to RJ-48C. Refer to the NMS Signal Entry Panel User's Manual (http://www.nmscommunications.com/swDocs/Docs/62576-13/default.htm) for more information on these SEPs.

For information on connecting from these SEPs to 75-ohm trunks, refer to “NMS BNC SEPs and Cables” below.

2. CG boards with RJ-45/RJ-48C connectors can be configured for T1, E1/120, or E1/75. These boards do not require a balun for connecting to a 75-ohm E1 trunk, although care must be taken regarding board set-up depending on the connection method used (see below).

    Specifically, the boards in this category include:

·          1- and 2-trunk CG 6060 PCI boards (RJ-48C)

·          4-trunk CG 6060 PCI boards (RJ-45)

·          4- and 8-trunk CG 6060C boards (RJ-48C only, not RJ-21)

·          4-trunk C 6565 PCI boards (RJ-45)

NMS BNC SEPs and Cables

NMS SEPs

NMS offers SEPs for connecting from RJ-48C to BNC (Figure 1) and RJ-45 to BNC (Figure 2).

Figure 1: RJ-48C to BNC SEP

These SEPS are available as P/N 82783-8 and 82783-16 (8/16 x RJ-48C to (1) 75 ohm BNC connector pair).

Figure 2: RJ-45 to BNC SEP

These SEPs are available as P/N 82779-2, 82779-4, 82779-6, 82779-8 (2/4/6/8 x NMS RJ-45 to (2) 75 ohm BNC connector pairs).

All NMS SEPs with BNC interfaces include baluns to convert impedance (E1/120 on the RJ-48C or RJ-45 connectors, and E1/75 on the BNC connectors).

For more information about all of the SEPs required to connect a given board, and how to connect the cables, please refer to the NMS Signal Entry Panel User's Manual.

Splitter Cables

NMS offers two cables for connecting from RJ-48C to BNC (Figure 3) and RJ-45 to BNC (Figure 4).

Figure 3: RJ-48C to BNC splitter cable (one trunk per cable; P/N 31067)

Figure 4: RJ-45 to BNC splitter cable (two trunks per cable; P/N 32854)

These NMS splitter cables do not convert impedance; they are 75 ohms on both ends of the cable.