Harris M7300 Installation And Product Safety Manual page 17

MM-014763-001, Rev. E
lid. Several different types of external-mount antennas are approved and available for use with the radio,
as listed in Table 1-1 (for VHF radios) and Table 1-2 (for 700 and 800 MHz radios), and in Table 4-5.
Front-mount and remote-mount configurations are available. In the front-mount configuration, the control
head is an integral part of the mobile radio. In the remote-mount configuration of the M7300, the control
head is located near the radio operator's position and the radio is mounted remotely from the control head,
typically in the vehicle's trunk. The remote-mount radio is shown in Figure 5-3 on page 28.
Control heads used with the M7300 radio include the CH-721 Scan and the CH-721 System model
control heads. See Figure 8-5 (page 55) through Figure 8-7. Both heads feature a large 3-line graphical
vacuum-florescent display, front panel controls and buttons for user control of the mobile radio, an
internal high-power audio amplifier to drive an externally-connected speaker, and a front panel
microphone connector. The CH-721 System control head also has a 12-button numeric keypad that
provides Dual-Tone Multi-Frequency (DTMF) functionality and easier operator system/group selection
control at the control head's front panel.
The remote-mount M7300 radio is designed for remote mounting in a motor vehicle's trunk, or some
other preferably unoccupied section in a vehicle, such as a fire truck's equipment shelf. Up to four (4)
control heads can be connected to a front-mount M7300, and up to five (5) control heads can be
connected to a remote-mount M7300. The radio is remotely controlled by a control head(s) connected to
it via 3-wire Controller Area Network (CAN) cables. Between the radio and control head(s), the CAN
link carries digitized microphone and speaker audio, controlling data such as button presses and radio
messages, and user data such as that for a mobile data terminal connected to the serial port of the radio or
control head. For proper operation, the CAN link must be terminated appropriately on each end. In
multiple control head installations, two or more control heads are interconnected to the mobile radio in a
series ("daisy-chain") fashion via CAN link cables.
As shown in Figure 8-7 on page 56, the CH-721 Scan and System model control heads used in remote-
mount radio installations have several connectors located on the head's rear panel. These connectors
include a DC power connector, two (2) CAN port connectors used for CAN link interconnections, an
external speaker connector, a 9-pin serial port connector for connecting optional equipment such as a
mobile data terminal, and a 25-pin accessory connector. Both CH-721 models can interface to an optional
Federal Signal Electronic siren/light control system for broadcasting via a public address (PA) speaker.
The radio must be powered by an external +13.6-volt (nominal) DC power source. In mobile applications,
the motor vehicle's electrical system is utilized as the source of DC power. In a remote-mount radio
installation, the control head(s) connected to the radio is also powered by the same DC power source, but
separately fused. When the control head is powered-up by the operator, it "wakes up" the radio by
transmitting data to the radio via the CAN link.
The radio provides half-duplex voice and data communications. Voice communications are accomplished
via a "push-to-talk" (PTT) type microphone and a speaker connected to the control head.
For data communications, the radio has an industry-standard 9-pin serial interface port for connecting
optional data-type equipment, such as a Mobile Data Terminal (MDT), a laptop PC, an external display,
or a key-entry device. This port works seamlessly with equipment from popular manufacturers and off-
the-shelf applications. OpenSky employs User Datagram Protocol over Internet Protocol (UDP/IP) data
packet transfers, providing "plug and play" connectivity for data-type devices.
The radio has an optional built-in Global Positioning System (GPS) tracking receiver. GPS provides
quick and accurate unit location information to dispatchers via the radio network. The GPS receiver
determines the unit's location and the radio transmits it to the radio network. The GPS antenna can be
integrated into the mobile transmit/receive antenna (i.e., a "combination" antenna). Alternately, the GPS
antenna can be located/mounted completely separate from the mobile transmit/receive antenna.
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