Users Manual Part 1

7.1.1
CAN Bus
The intercommunication between the RFDS units (the Duplexers, Post Filters, and Cavity Combiners)
and the Site Controller is carried out through the CAN Bus at 125 kB/second. The connectors for the
CAN Bus are RJ45 connectors. The CAN Bus is terminated at each end, either by the Site Controller
or by an RJ45 terminator.
Each device is registered at the Site Controller (SC), which specifies the particular channel for each
unit. Every 30 seconds, each unit on the CAN Bus transmits status and alarm information. Alarms are
triggered when any thresholds are exceeded, (failure alarms, software revisions, and so on). The
following common information is available from the CAN Bus: serial number, TrackID, software
revisions, and the Motorola Solutions kit number. For each unit, specific information is available, for
example, voltage standing wave ratio (VSWR) for DPMs and tuning information for Cavity Combiners.
The receive path of the Preselector or Duplexer is not connected to the CAN Bus. Because the supply
voltage is supplied from the Base Radio, the Base Radio can withstand a short or 50 ohms connection
to the RX input without the Base Radio or the Power Supply Unit (PSU) being damaged.
For more information on CAN Bus, see Site Controller CAN Bus on page 327.
7.1.2
RFDS Frequency Band and Bandwidth
The following table contains all the frequency bands available in MTS LiTE, MTS 2, and MTS 4.
Table 80: RFDS Frequency Bands and Bandwidth
Frequency Band
MTS Version Filter Bandwidth Duplex Spacing
350 MHz – 470 MHz
• MTS LiTE
• MTS 2
• MTS 4
5 MHz 10 MHz
260 MHz – 275 MHz
• MTS 2
• MTS 4
6 MHz 9 MHz
851 MHz – 870 MHz
• MTS LiTE
• MTS 2
• MTS 4
19 MHz 45 MHz
7.2
MTS LiTE and MTS 2 RFDS
In terms of RFDS, MTS 2 uses a low-power, cost effective RFDS placed on top of a card cage,
intended for up to 2 Base Radios. For MTS LiTE, the RFDS is placed beside the card cage intended
for only 1 Base Radio.
The RFDS in MTS LiTE and MTS 2 is made up of the following:
• One or two Preselectors with integrated high performance low noise amplifier (LNA). The supply
voltage for the LNA is supplied through the RX out connected to the Base Radios. The Preselector
has two outlets for two Base Radios. The dimensions of the filter are: 85 x 280 x 70 mm, excluding
connectors. The antenna connectors are DIN 7–16, the receive side is connected with QMA
connectors. See the block schematic of the MTS LiTE/MTS 2 Preselector in Figure 143: Schematic
Diagram of MTS LiTE / MTS 2 Preselector on page 282.
6802800U74-AP
Chapter
7: Radio Frequency Distribution System
275