Clear-Com EF-701M - Manual (Page 16)

1 - 6 E F - 7 0 1 M I N T E R F A C E
horizontally in one-rack unit (1RU) of space and will offer sufficient vertical clearance to
accommodate a variety of mounting methods. While the EF-701M may be used as a
single-ended 4-wire-to-party-line interface with excellent results, it is uniquely equipped
to work in point-to-point pairs. Much of the discussion in this manual addresses the
issues of operation in this latter mode.
Due to the superior nulling capability of the EF-701M, more than a single pair of
EF-701M units can be used to link various locations to a single channel.
As an example consider the following scenario: The three Channel A ports of an MS-702
main station are each connected to an EF-701M. (For an illustration, see Figure 1-4.)
Each of those three is in turn connected to a fiber-optic modem and sent through fiber to
another fiber-optic modem, EF-701M unit, and party-line system at the three remote
destinations. All four locations are now sharing the same channel, linked through fiber,
with a total of six “nulls” on the channel. While the nature of 2-wire to 4-wire hybrids
may limit the maximum number of external 2-wire party lines that can be combined, six
EF-701M units on a common channel, properly nulled, should generally provide a stable
system.
Because the EF-701M will be used with a wide variety of third-party systems and devices,
it is not possible to address all the variables of setups and transmission methods. The key
point is that the modem, multiplexer, or converter for the transmission medium (the