User's Manual

Mojix
®
STAR 1000 System User Manual
19
4. eMux Installation
eNodes frequently are deployed with multiplexers (eMux’s) that can connect multiple eNodes to a STAR or to another
(upstream) eMux. The eMux amplifies and conditions RF signals from the STAR and provides DC power to eNodes.
This section describes the steps to installing an eMux. eMux’s should be used either when:
(1) The insertion loss from coaxial cables and eNodes is too great
(2) The wired eNode system layout requires splitting the wiring to multiple wiring branches.
Star Receiver
eMux
eNode
STAR
Figure 17: Example wiring diagram for eNodes and eMux’s
4.1. About Insertion Loss
The STAR puts out a signal of +22 dBm. Approximate insertion loss of terminated LMR240 coaxial cable at 915 MHz is
~7.5 dBm per 100 ft. Approximate insertion loss of wired eNodes is 0.5 dBm. If the input power level on coaxial cable
as an input to either an eMux or an eNode must be greater than or equal to -10 dBm. If the power level falls below this
level, eNodes may miscalibrate causing the middle yellow LED to blink, or even go dark. In order to increase the signal
strength for longer cable runs or many eNodes strung together, an eMux can be used to amplify the signal.
4.2. eMux Specifications
Figure 18 depicts the eMux and its interfaces, showing the RF connections as well as the power supply and calibration
dial. The connector specification is summarized in Table 8.